Collect. Czech. Chem. Commun.
1972, 37, 2066-2076
https://doi.org/10.1135/cccc19722066
Nucleic acid components and their analogues. CL. Preparation and properties of some nucleoside hydroxyalkanephosphonates
A. Holý and Ng. D. Hong
Individual author index pages
Other CCCC articles of these authors
- H. Dvořáková, A. Holý, M. Masojídková, I. Votruba, J. Balzarini, R. Snoeck and E. De Clercq
Synthesis and antiviral activity of acyclic nucleoside and nucleotide derivatives of 8-azaadenine
1993, Vol. 58, Special Issue, pp. S253–S255 [Abstract] - D. Hocková, A. Holý and H. Dvořáková
Acyclic nucleoside analogues derived from 2-azapurines
1993, Vol. 58, Special Issue, pp. S250–S252 [Abstract] - Z. Janeba, H. Dvořáková and A. Holý
Studies on acyclic anhydro nucleosides. Formation and reactivity of seven-membered cyclic structures
1993, Vol. 58, Special Issue, pp. S247–S249 [Abstract] - K. Juricová, A. Holý, S. Smrčková, M. Spassova and H. Dvořáková
Synthesis of base-modified "abbreviated" acyclic NAD-analogues
1993, Vol. 58, Special Issue, pp. S244–S246 [Abstract] - J. Brokeš and A. Holý
Synthesis of 5'-O-phosphonomethyl derivatives of biologically active nucleosides
1990, Vol. 55, Special Issue, pp. S125–S128 [Abstract] - H. Dvořáková, A. Holý, R. Snoeck, J. Balzarini and E. De Clercq
Acyclic nucleoside and nucleotide analogues derived from 1-deaza and 3-deazaadenine
1990, Vol. 55, Special Issue, pp. S113–S116 [Abstract] - M. Spassova and A. Holý
N-(3-Azido-2-hydroxypropyl) derivatives of purine and pyrimidine bases
1990, Vol. 55, Special Issue, pp. S65–S68 [Abstract] - D. Cech, H. Beerbaum and A. Holý
A simple synthesis of 5-fluoro-2-pyrimidinone and its N1-substituted derivatives
1977, Vol. 42, Issue 9, pp. 2694–2700 [Abstract] - V. Pačes, I. Rosenberg, M. Kamínek and A. Holý
Metabolism of cytokinins in rape seedlings (Brassica napus L.)
1977, Vol. 42, Issue 8, pp. 2452–2458 [Abstract] - A. Holý and H. Pischel
Preparation of 5'-O-carboxymethyluridine and its 5-halo derivatives
1977, Vol. 42, Issue 7, pp. 2261–2265 [Abstract] - D. Cech and A. Holý
Preparation of 2-pyrimidinone nucleosides from uracil nucleosides
1977, Vol. 42, Issue 7, pp. 2246–2260 [Abstract] - A. Holý
Preparation of acyl derivatives of pyrimidin-2-one nucleosides by the silyl variant of the Hilbert-Johnson reaction
1977, Vol. 42, Issue 3, pp. 902–908 [Abstract] - J. Doskočil and A. Holý
Specificity of purine nucleoside phosphorylase from Escherichia coli
1977, Vol. 42, Issue 1, pp. 370–383 [Abstract] - D. Cech and A. Holý
Preparation of some 2'-deoxy-5-fluorouridine derivatives by a direct fluorination
1976, Vol. 41, Issue 11, pp. 3335–3342 [Abstract] - A. Holý and M. Plšek
Substrate specificity of rape pollen 3'-nucleotidase (Brassica napus)
1976, Vol. 41, Issue 8, pp. 2433–2439 [Abstract] - A. Holý
New synthesis of ribonucleoside carbocyclic analogues
1976, Vol. 41, Issue 7, pp. 2096–2109 [Abstract] - A. Holý and M. Plšek
Properties of ribonuclease, phosphodiesterase, and decyclizing phosphodiesterase from rape (Brassica napus L.) pollen
1976, Vol. 41, Issue 5, pp. 1612–1626 [Abstract] - A. Holý, M. Plšek and O. Haragsim
Identification of main nucleolytic activities of the bee-gathered rape pollen (Brassica napus L.)
1976, Vol. 41, Issue 5, pp. 1598–1611 [Abstract] - A. Holý
Preparation of substituted (±)-5t-hydroxymethyl-3t-aminocyclopentane-1r,2c-diol derivatives related to carbocyclic ribonucleoside analogues
1976, Vol. 41, Issue 2, pp. 647–665 [Abstract] - A. M. Kritzyn and A. Holý
Stereospecific synthesis of β-D-ribopyranosyl nucleoside analogues
1975, Vol. 40, Issue 10, pp. 3211–3219 [Abstract] - H. Pischel, A. Holý, G. Wagner and D. Cech
Carboxymethylated uracil, 2'-deoxyuridine and their 5-fluoro, 5-bromo, and 5-iodo derivatives
1975, Vol. 40, Issue 9, pp. 2689–2699 [Abstract] - V. Uchytilová, A. Holý, D. Cech and J. Gut
Preparation of 2-pyrimidinone and derivatives
1975, Vol. 40, Issue 8, pp. 2347–2352 [Abstract] - A. Holý
Preparation of orotidine, 2'-deoxyorotidine, and related compounds
1975, Vol. 40, Issue 3, pp. 738–752 [Abstract] - A. Holý
Aliphatic analogues of nucleosides, nucleotides, and oligonucleotides
1975, Vol. 40, Issue 1, pp. 187–214 [Abstract] - H. Pischel, A. Holý and G. Wagner
6-Azauridine-5'-uronic acid and related compounds: Synthesis and binding to proteins
1974, Vol. 39, Issue 12, pp. 3773–3781 [Abstract] - A. Holý and H. Pischel
Preparation of 5'-O-carboxymethylcytidine and 5'-O-carboxymethyl-1-(β-D-arabinofuranosyl)cytosine
1974, Vol. 39, Issue 12, pp. 3763–3772 [Abstract] - A. Holý
Preparation of 6-methyluridine, 6-ethyluridine, and 2'-deoxy-6-ethyluridine
1974, Vol. 39, Issue 11, pp. 3374–3382 [Abstract] - A. Holý
Reaction of sugar 2-amino[1',2':4,5]oxazolines with substituted alkyl β-halo- and β-alkoxyacrylates
1974, Vol. 39, Issue 11, pp. 3177–3186 [Abstract] - A. Holý and D. Cech
Synthesis of 2'-deoxythymidine, 2'-deoxy-5-fluorouridine, and 2'-deoxy-6-azauridine from ribonucleosides
1974, Vol. 39, Issue 11, pp. 3157–3167 [Abstract] - G. S. Ivanova, A. Holý, E. Zelinková, S. I. Bezborodova, N. M. Abrosimova-Amelyanchik and R. I. Tatarskaya
Substrate specificity of some microbial guanyloribonucleases
1974, Vol. 39, Issue 10, pp. 2986–2997 [Abstract] - A. Holý and I. Votruba
Substrate specificity of bacterial thymidylate-synthetase
1974, Vol. 39, Issue 6, pp. 1646–1661 [Abstract] - G. S. Ivanova, A. Holý and S. I. Bezborodova
Substrate requirements of some microbial ribonucleases non-specific to natural bases
1974, Vol. 39, Issue 4, pp. 993–1004 [Abstract] - A. Holý, I. Votruba and K. Jošt
S-(Pyrimidin-2-yl)-L-cysteine: Chemical synthesis and biosynthesis in Escherichia coli
1974, Vol. 39, Issue 2, pp. 634–646 [Abstract] - A. Holý
Substrate specificity of spleen acid exonuclease and spleen cyclic phosphodiesterase
1974, Vol. 39, Issue 1, pp. 310–332 [Abstract] - A. Holý
Nucleic acid components and their analogues. CLXII. Preparation of 6-methyl-2'-deoxyuridine and related compounds
1973, Vol. 38, Issue 12, pp. 3912–3931 [Abstract] - R. Wightman and A. Holý
Nucleic acid components and their analogues. CLIX. Synthesis of some 2-pyrimidone nucleosides
1973, Vol. 38, Issue 5, pp. 1381–1397 [Abstract] - A. Holý and Z. Arnold
Nucleic acid components and their analogues. CLVIII. Preparation of some substituted 2-amino- and 2-mercaptopyrimidines from trimethinium salts
1973, Vol. 38, Issue 5, pp. 1371–1380 [Abstract] - V. Pačes and A. Holý
Inhibition of protein synthesis by pyrimidone-(2)-ribofuranoside in Escherichia coli
1973, Vol. 38, Issue 4, pp. 1268–1272 [Abstract] - A. Holý
Nucleic acid components and their analogues. CLVI. Preparation of enantiometric 1-(α-xylofuranosyl), 1-(α-lyxofuranosyl), and 1-(2-deoxy-α-lyxofuranosyl) derivatives of uracil and cytosine
1973, Vol. 38, Issue 2, pp. 428–437 [Abstract] - A. Holý
Nucleic acid components and their analogues. CLV. Mechanism of anomalous opening of the O2,2'-anhydro bond in uracil cyclonucleosides
1973, Vol. 38, Issue 2, pp. 423–427 [Abstract] - A. Holý
Nucleic acid components and their analogues. CLIV. Nucleoside and nucleotide derivatives of α-uridine, 2'-deoxy-α-uridine and 2'-deoxy-α-cytidine, and their affinity towards nucleolytic enzymes
1973, Vol. 38, Issue 1, pp. 100–114 [Abstract] - A. Holý
Nucleic acid components and their analogues. CLIII. Preparation of 2'-deoxy-L-ribonucleosides of the pyrimidine series
1972, Vol. 37, Issue 12, pp. 4072–4087 [Abstract] - H. Pischel, A. Holý and G. Wagner
Glykoside von Heterocyclen XLV. Riboside von Pyrimidonen
1972, Vol. 37, Issue 10, pp. 3475–3482 [Abstract] - I. Votruba, A. Holý and H. Pischel
Inhibition of DNA synthesis in Escherichia coli by 1-(β-D-ribofuranosyl)-2-pyrimidone
1972, Vol. 37, Issue 7, pp. 2213–2220 [Abstract] - Z. Kučerová, A. Holý and R. W. Bald
Nucleic acid components and their analogues. CXLVIII. Preparation of some nucleotidic derivatives of orotidine
1972, Vol. 37, Issue 6, pp. 2052–2058 [Abstract] - A. Holý
Nucleic acid components and their analogues. CXLVII. Preparation of 5-ethoxycarbonyluridine, 5-carboxyuridine and their nucleotidic derivatives
1972, Vol. 37, Issue 5, pp. 1555–1576 [Abstract] - A. Holý, R. W. Bald and F. Šorm
Nucleic acid components and their analogues. CXLVI. Preparation of some nucleotide derivatives of 6-methyluridine, 3-(β-D-ribofuranosyl)uracil, and 3-(β-D-ribofuranosyl)-6-methyluracil. Investigations of their template activity and behaviour towards some nucleolytic enzymes
1972, Vol. 37, Issue 2, pp. 592–602 [Abstract] - R. W. Bald and A. Holý
Nucleic acid components and their analogues. CXLII. Preparation of 3-(β-D-ribofuranosyl)uracil 2',3'-cyclic phosphate and related compounds and their behaviour towards pancreatic ribonuclease and ribonuclease T2
1971, Vol. 36, Issue 11, pp. 3657–3669 [Abstract] - A. Holý and F. Šorm
Nucleic acid components and their analogues. CXL. Preparation of 5'-L-ribonucleotides, some of their derivatives, and 2'(3')→5'-homooligo-L-ribonucleotides; coding properties of L-ribonucleoside-containing oligonucleotides
1971, Vol. 36, Issue 9, pp. 3282–3299 [Abstract] - A. Holý and R. Bald
Nucleic acid components and their analogues. CXXXVIII. Synthesis of 2',3'-cyclic phosphates derived from some pyrimidine ribonucleosides and their behaviour towards pancreatic ribonuclease and ribonuclease T2
1971, Vol. 36, Issue 8, pp. 2809–2823 [Abstract] - A. Holý, R. W. Bald and Ng. D. Hong
Nucleic acid components and their analogues. CXXXVII. Preparation and properties of some N-(2-hydroxyethyl) derivatives of ribonucleosides and nucleotides
1971, Vol. 36, Issue 7, pp. 2658–2676 [Abstract] - A. Holý and Ng. D. Hong
Synthesis of ribonucleoside 5'-O-hydroxymethanephosphonates
1971, Vol. 36, Issue 1, pp. 316–317 [Abstract] - A. Holý
Oligonucleotidic compounds. XXXVIII. Synthesis of diribonucleoside phosphates and triribonucleoside diphosphates derived from adenosine 3'-phosphate and guanosine 3'-phosphate: A general approach to the synthesis of oligonucleotides
1970, Vol. 35, Issue 12, pp. 3686–3711 [Abstract] - H. Pischel and A. Holý
Oligonucleotid-Verbindungen XXXVII. Synthese einiger Nucleotid-Derivate von 1-(β-D-Ribofuranosyl)pyrimidon-(2) und 3-(β-D-Ribofuranosyl)pyrimidon-(4)
1970, Vol. 35, Issue 12, pp. 3584–3596 [Abstract] - A. Holý
Nucleic acid components and their analogues. CXXX. Preparation of nucleotide derivatives of 1'-homouridine and their behaviour towards some nucleolytic enzymes
1970, Vol. 35, Issue 1, pp. 81–88 [Abstract] - A. Holý and J. Žemlička
Oligonucleotidic compounds. XXXV. Reaction of diribonucleoside phosphates with dimethylformamide acetals
1969, Vol. 34, Issue 12, pp. 3921–3935 [Abstract] - A. Holý and F. Šorm
Nucleic acid components and their analogues CXXIX. Synthesis of enantiomeric 2',3'-cyclic phosphates of 9-(α-lyxofuranosyl)adenine and -hypoxanthine and their behaviour towards ribonuclease T1 and T2
1969, Vol. 34, Issue 11, pp. 3523–3532 [Abstract] - A. Holý
Nucleic acid components and their analogues. CXXVIII. Phosphorylation of some thymine 1-pentopyranosyl and 1-hexopyranosyl derivatives by the reaction with triethyl phosphite and hexachloroacetone
1969, Vol. 34, Issue 11, pp. 3510–3522 [Abstract] - A. Holý and F. Šorm
Oligonucleotidic compounds. XXXIV. Preparation of some β-L-ribonucleosides, their 2'(3')-phosphates and 2',3'-cyclic phosphates
1969, Vol. 34, Issue 11, pp. 3383–3401 [Abstract] - A. Holý and J. Žemlička
Oligonucleotidic compounds. XXXIII. A study on hydrolysis of N-dimethylaminomethylenecytidine, -adenosine, -guanosine, and related 2'-deoxy compounds
1969, Vol. 34, Issue 8, pp. 2449–2458 [Abstract] - A. Holý and F. Šorm
Oligonucleotidic compounds. XXXII. Phosphorylation of 1-lyxofuranosyl, 1-xylofuranosyl and 1-arabinofuranosyl derivatives of uracil and thymine with triethyl phosphite and hexachloroacetone
1969, Vol. 34, Issue 7, pp. 1929–1953 [Abstract] - A. Holý
Oligonucleotidic compounds. XXX. Synthesis of some 5'-O-substituted derivatives of guanosine 2',3'-cyclic phosphate and guanylyl-(3'→5')-uridine
1969, Vol. 34, Issue 4, pp. 1261–1277 [Abstract] - A. Holý, S. Chládek and J. Žemlička
Oligonucleotidic compounds. XXIX. Reactions of ribonucleoside 2'(3')-phosphates with dimethylformamide acetals
1969, Vol. 34, Issue 1, pp. 253–271 [Abstract] - H. Pischel and A. Holý
Oligonucleotid-Verbindungen XXVIII. Synthese von (3'→5')-Diribonucleosidphosphaten von 1-(β-D-Ribofuranosyl)-pyridon-(2) und 2-(β-D-Ribofuranosyl)-pyridazon-(3)
1969, Vol. 34, Issue 1, pp. 89–102 [Abstract] - Z. Kučerová, J. Škoda, A. Holý and F. Šorm
Factors affecting the cleavage of adenosine and uridine 5'-phosphites by the venom of Vipera russelli
1968, Vol. 33, Issue 12, pp. 4350–4355 [Abstract] - V. Lisý, J. Škoda, I. Rychlík, J. Smrt, A. Holý and F. Šorm
Changes in coding properties of poly- and oligonucleotides containing 6-azapyrimidine ribonucleosides
1968, Vol. 33, Issue 12, pp. 4111–4119 [Abstract] - D. Grünberger, A. Holý, J. Smrt and F. Šorm
Effect of substitution of halogen or N3-methyl derivatives of uridine for uridine in trinucleotide codons on their recognition by aminoacyl-[14C]-tRNA
1968, Vol. 33, Issue 11, pp. 3858–3865 [Abstract] - A. Holý, J. Smrt and F. Šorm
Oligonucleotidic compounds. XXVII. Synthesis of diribonucleoside phosphates containing 5-halo derivatives of uridine and 3-methyluridine
1968, Vol. 33, Issue 11, pp. 3809–3822 [Abstract] - M. P. Mertes, A. Holý and J. Smrt
Oligonucleotidic compounds. XXVI. Synthesis of uridylyl-(3'→5')-N4-hydroxy-6-azacytidine and N4-hydroxy-6-azacytidylyl-(3'→5')-uridine
1968, Vol. 33, Issue 10, pp. 3313–3323 [Abstract] - A. Holý
Oligonucleotidic compounds. XXIV. Synthesis of 2',3'-cyclic phosphates of inosine, xanthosine, 9-(β-D-ribofuranosyl)-6-mercaptopurine, and 9-(β-D-ribofuranosyl)-2-amino-6-mercaptopurine
1968, Vol. 33, Issue 7, pp. 2245–2256 [Abstract] - H. Pischel and A. Holý
Nucleinsäure-Komponenten und ihre Analoga CXIV. Synthese der 5'-Diphosphate von 1-(β-D-Ribofuranosyl)-pyridon-(2) und 2-(β-D-Ribofuranosyl)-pyridazon-(3)
1968, Vol. 33, Issue 7, pp. 2066–2073 [Abstract] - D. Grünberger, A. Holý and F. Šorm
Synthesis of triribonucleoside diphosphates with ribonuclease T1
1968, Vol. 33, Issue 1, pp. 286–295 [Abstract] - A. Holý
Oligonucleotidic compounds. XXI. Synthesis of (3'→5')-diribonucleoside phosphate 2',3'-cyclic phosphates from unprotected (3'→5')-diribonucleoside phosphates
1968, Vol. 33, Issue 1, pp. 223–231 [Abstract] - A. Holý and H. Pischel
Oligonucleotidic compounds. XX. A general method for the synthesis of 5'-O-phosphorylribonucleoside 2',3'-cyclic phosphates
1967, Vol. 32, Issue 10, pp. 3719–3725 [Abstract] - A. Holý
Nucleic acid components and their analogues. IC. Synthesis of 6-azauridine 5'-methanephosphonate and 6-azauridine (2')3'-methanephosphonate
1967, Vol. 32, Issue 10, pp. 3713–3718 [Abstract] - J. Žemlička and A. Holý
Preparation of N-dimethylaminomethylene derivatives - A new method of a selective substitution of nucleoside amino groups
1967, Vol. 32, Issue 9, pp. 3159–3168 [Abstract] - A. Holý
Nucleic acids components and their analogues. XCV. Synthesis of ribonucleoside 5'-phosphites
1967, Vol. 32, Issue 8, pp. 3064–3067 [Abstract] - A. Holý, J. Smrt and F. Šorm
Oligonucleotidic compounds. XVII. Synthesis of oligonucleotides containing 6-azauridine and 6-azacytidine
1967, Vol. 32, Issue 8, pp. 2980–2997 [Abstract] - D. Grünberger, L. Meissner, A. Holý and F. Šorm
The coding properties of polymers and trinucleoside diphosphates containing 8-azaguanosine
1967, Vol. 32, Issue 7, pp. 2625–2633 [Abstract] - Z. Kučerová, A. Holý, J. Škoda and F. Šorm
Release of inorganic phosphite from nucleoside 5'-phosphites by Russell's viper venom
1967, Vol. 32, Issue 5, pp. 2038–2041 [Abstract] - A. Holý and J. Smrt
Oligonucleotidic compounds. XV. A general approach to the stepwise synthesis of ribooligonucleotides. Synthesis of some triribonucleoside diphosphates
1966, Vol. 31, Issue 9, pp. 3800–3816 [Abstract] - J. Žemlička, S. Chládek, A. Holý and J. Smrt
Oligonucleotidic compounds. XIV. Synthesis of some diribonucleoside phosphates using the N-dimethylaminomethylene derivatives of 2',3'-O-ethoxymethylene ribonucleosides
1966, Vol. 31, Issue 8, pp. 3198–3212 [Abstract] - A. Holý
Nucleic acids components and their analogues. LXXXIV. Synthesis of some derivatives of N1-formyl- and N1,N5-diformylbiuret
1966, Vol. 31, Issue 7, pp. 2973–2977 [Abstract] - A. Holý and F. Šorm
Nucleic acids components and their analogues. LXXXI. A selective synthesis of ribonucleoside-2'(3') phosphites
1966, Vol. 31, Issue 4, pp. 1562–1568 [Abstract] - A. Holý and F. Šorm
Nucleic acids components and their analogues. LXXX. Preparation of nucleoside phosphites by reacion of nucleosides with triphenyl phosphite
1966, Vol. 31, Issue 4, pp. 1544–1561 [Abstract] - A. Holý and J. Smrt
Oligonucleotidic compounds. XI. Synthesis of ribonucleoside-2',3' cyclophosphates from nucleosides via nucleoside 2',3'-phosphites
1966, Vol. 31, Issue 4, pp. 1528–1534 [Abstract] - A. Holý, J. Krupička and Z. Arnold
The polarographic behaviour of polymethinium salts
1965, Vol. 30, Issue 12, pp. 4127–4142 [Abstract] - A. Holý, J. Smrt and F. Šorm
Nucleic acids components and their analogues. LXXI. Oxidation of nucleoside 5'-phosphites on treatment with halo acid derivatives and hexachloroacetone
1965, Vol. 30, Issue 10, pp. 3309–3319 [Abstract] - A. Holý, J. Smrt and F. Šorm
Nucleic acids components and their analogues. LIX. The preparation and properties of nucleoside phosphites
1965, Vol. 30, Issue 5, pp. 1635–1642 [Abstract] - A. Holý and Z. Arnold
The formation of a pyrrole derivative during the reaction of 1-phenyltrimethinium salt with sodium hydride
1965, Vol. 30, Issue 1, pp. 346–348 [Abstract] - A. Holý and Z. Arnold
Synthetic reactions of dimethylformamide. XXI. The formation of aromatic compounds during the formylation reactions
1965, Vol. 30, Issue 1, pp. 53–60 [Abstract] - Z. Arnold and A. Holý
Synthetic reactions of dimethylformamide. XX. Preparation of some vinylogous polymethinium systems
1965, Vol. 30, Issue 1, pp. 47–52 [Abstract] - Z. Arnold and A. Holý
The preparation of substituted pentamethinium salts
1965, Vol. 30, Issue 1, pp. 40–46 [Abstract] - A. Holý, N. Ch. Spasovska and J. Smrt
Synthesis of 6-azauridylyl-(5'→5')-6-azauridine and P1,P2-di-(6-azauridylyl-5')-pyrophosphate
1964, Vol. 29, Issue 10, pp. 2567–2570 [Abstract] - Z. Arnold and A. Holý
Synthetic reactions of dimethylformamide. XVIII. Reactivity of methyl groups in polymethinium salts
1963, Vol. 28, Issue 8, pp. 2040–2046 [Abstract] - Z. Arnold and A. Holý
Synthetische Reaktionen von Dimethylformamid XVII. Darstellung von Acylmalondialdehyden durch Formylierung von Trimethiniumsalzen
1963, Vol. 28, Issue 4, pp. 869–881 [Abstract] - Z. Arnold and A. Holý
Synthetic reactions of dimethylformamide. XIV. Some new findings on adducts of the Vilsmeier-Haack type
1962, Vol. 27, Issue 12, pp. 2886–2897 [Abstract] - A. Holý and A. Vystrčil
Studie der Aurone II. Über die Reaktivität der Carbonylgruppe in Auronen
1962, Vol. 27, Issue 8, pp. 1861–1869 [Abstract] - Z. Arnold and A. Holý
Synthetic reactions of dimethylformamide. XIII. β-Bromoacraldehydes
1961, Vol. 26, Issue 12, pp. 3059–3073 [Abstract] - A. Holý
Studie der Aurone I. Polarographisches Verhalten des 2-Benzalcumaranons-(3) vorläufige Mitteilung
1958, Vol. 23, Issue 11, pp. 2131–2134 [Abstract]