全文获取类型
收费全文 | 273篇 |
免费 | 13篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2019年 | 2篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 18篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 19篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 7篇 |
2001年 | 18篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有286条查询结果,搜索用时 15 毫秒
51.
L. V. Starostenko E. A. Maltseva N. A. Lebedeva P. E. Pestryakov O. I. Lavrik N. I. Rechkunova 《Biochemistry. Biokhimii?a》2016,81(3):233-241
The combined action of reactive metabolites of benzo[a]pyrene (B[a]P) and oxidative stress can lead to cluster-type DNA damage that includes both a bulky lesion and an apurinic/apyrimidinic (AP) site, which are repaired by the nucleotide and base excision repair mechanisms — NER and BER, respectively. Interaction of NER protein XPC—RAD23B providing primary damage recognition with DNA duplexes containing a B[a]P-derived residue linked to the exocyclic amino group of a guanine (BPDE-N2-dG) in the central position of one strand and AP site in different positions of the other strand was analyzed. It was found that XPC—RAD23B crosslinks to DNA containing (+)-trans-BPDE-N2-dG more effectively than to DNA containing cis-isomer, independently of the AP site position in the opposite strand; protein affinity to DNA containing one of the BPDE-N2-dG isomers depends on the AP site position in the opposite strand. The influence of XPC—RAD23B on hydrolysis of an AP site clustered with BPDE-N2-dG catalyzed by the apurinic/apyrimidinic endonuclease 1 (APE1) was examined. XPC—RAD23B was shown to stimulate the endonuclease and inhibit the 3′–5′ exonuclease activity of APE1. These data demonstrate the possibility of cooperation of two proteins belonging to different DNA repair systems in the repair of cluster-type DNA damage. 相似文献
52.
O I Lavrik G A Nevinski? I A Potapova N B Tarusova O V Khalabuda 《Molekuliarnaia biologiia》1989,23(2):400-408
The modification of tyrosine residues of the human placenta DNA-polymerase alpha by N-acetylimidazole was investigated. The poly(dT)-template and the r(pA)10-primer a each added separately or simultaneously do not influence the rate of enzyme inactivation. In the presence of poly(dT)-r(pA)10 no effect of dCTP and dTTP (noncomplementary to template) and of dAMP and dADP (complementary to template) on the rate and the level of the enzyme inactivation was found. However dATP revealed practically complete protection. Orthophosphate, pyrophosphate each taken separately do not influence the rate of enzyme inactivation with this reagent. The presence of dADP with either ortho- or pyrophosphate, or dAMP with the one of these ligands leads to half protective action in comparison with dATP. Imidazolides of phosphonoacetic acid and 5'-adenylyl++ 1(phosphonoacetic acid) do not inactivate DNA-polymerase alpha from human placenta and the Klenov fragment of DNA-polymerase I from E. coli. All data obtained allow to suggest that the tyrosine residue in the dNTP binding site of DNA-polymerase reveals stacking with the nucleotide only if dNTP is complementary to the template. 相似文献
53.
The interaction of deoxyribonucleoside 5'-mono-, di- and triphosphates with human placenta DNA polymerase alpha was examined. Dissociation constants of enzyme complex formation with dNMP, dNDP and dNTP were determined from the data on enzyme affinity modification by imidazolide of dTMP. The basic role of the primary template-primer interaction with the enzyme in dNTP complex formation is shown. The template-dependent nucleotide interaction does not occur in the case of dNMP and dNDP in comparison with dNTP. The significant contribution of the gamma-phosphate of dNTP in this process is demonstrated. 相似文献
54.
The influence of P1,P3-bis(5'-adenosyl)triphosphate (Ap3A), P1,P4-bis(5'-adenosyl)tetraphosphate (Ap4A) and its analogues, containing a residue of methylenediphosphonic acid in various positions of the oligophosphate chain, on the reactions catalysed by phenylalanyl-tRNA synthetase from E. coli MRE-600 has been studied. The compounds do not affect significantly the rate of ATP-[32P]PPi-exchange nor maintain this reaction in the absence of ATP. The diadenosineoligophosphates are shown to be noncompetitive inhibitors of ATP in the tRNA aminoacylation by phenylalanine (for Ap4A Ki = 1,45.10(-3) M). The phosphonate analogues of Ap4A inhibit the synthesis of Ap3A depending on their structure. The conclusion is thus drawn that the E. coli MRE-600 phenylalanyl-tRNA synthetase does not interact property with Ap4A and its phosphonate analogues. 相似文献
55.
Affinity modification of E. coli DNA polymerase I and its Klenow fragment by imidazolides of dNMP (Im-dNMP) and dNTP was studied. DNA polymerase activity of DNA polymerase I was reduced by both Im-dNMP and Im-dNTP. However Im-dNTP does not inactivate of the Klenow fragment. The level of covalent labelling of both enzymes by radioactive Im-dNTP did not exceed 0.01 mol of reagent per mol of enzyme. But the deep inactivation of DNA polymerase I by Im-dNTP was observed. It is likely that this inactivation is due to the formation of intramolecular ether followed by phosphorylation of the carboxyl group. This assumption is strongly supported by the increase of the isoelectrical point of DNA polymerase I after its incubation with Im-dNTP in conditions of enzyme inactivation. All data permit us to suggest that the affinity modification of both enzymes by Im-dNMP and covalent labeling by Im-dNTP takes place without complementary binding of dNTP moiety with the template. However inactivation of DNA polymerase I by Im-dNTP occurs only if the dNTP-moiety is complementary to the template in the template.primer complex. It was shown that His residue was phosphorylated by Im-dNMP and Tyr or Ser residues between Met-802 and Met-848 were phosphorylated by Im-dNTP. We suppose that there are two states of DNA polymerase active site for the binding of dNTPs. One of them is independent on the template, in the other state the dNTP hydrogen bond with the template is formed. 相似文献
56.
V A Volchkova V V Gorn T I Kolocheva O I Lavrik A S Levina 《Bioorganicheskaia khimiia》1989,15(1):78-89
The modification of Klenow fragment of DNA polymerase I E. coli was investigated by the affinity reagents d(Tp)2C[Pt2+(NH3)2OH](pT)7 and d(pT)2pC[Pt2+(NH3)2OH](pT)7. The template binding site of the enzyme was modified by these reagents in the presence of NaF (5 mM), which inhibits selectively the 3'----5'-exonuclease activity of the enzyme and therefore prevents the reagent from degradation. NaCN destroyed covalent bonds between reagents and enzyme, restoring activity of the Klenow fragment. The affinity of different ligands (inorganic phosphate, nucleoside monophosphates, oligonucleotides) to the template binding site of Klenow fragment was estimated. Minimal ligands capable to bind with the template site were shown to be triethylphosphate (Kd 290 microM) and phosphate (Kd 26 microM). Ligand affinity increases by the factor 1.76 per an added (monomer unit from phosphate to d(pT) and then for oligonucleotides d(Tp)nT (n 1 to 19-20). At n greater than 19-20, the ligand affinity remained constant. The complete ethylation of phosphodiester groups lowers affinity of the oligothymidylates to the enzyme by approximately 10 times, and comparable decrease of Pt2+-oligonucleotide affinity to polymerase is caused by the absence of Mn2+-ions. The data obtained led to suggestion that one Me2+-dependent electrostatic contact of the template phosphodiester group with the enzyme takes place (delta G = -1.45...-1.75 kcal/mole). Formation of a hydrogen bond with the oxygen atom of P = O group of the same template phosphate is also assumed (delta G = -4.8...-4.9 kcal/mole). Other template internucleotide phosphates do not interact with the enzyme but the bases of oligonucleotides take part in hydrophobic interactions with the template binding site. Gibbs energy changes by -0.34 kcal/mole when the template is lengthened by one unit. 相似文献
57.
58.
Phenylalanyl-tRNA synthetase from Escherichia coli does not catalyze the [14C]phenylalanyl residue transfer from phenylalanyl-adenylate to adenosine either in the presence or absence of homologous tRNAPhe and tRNA(-A Phe). When the reaction mixture contained dithiothreitol, radioactive substance was detected having a mobility on HPLC column close to that of aminoacyladenosine. The amount of this product depended on the concentration of dithiothreitol in the mixture. Phenylalanyl residue was suggested to undergo transfer from aminoacyladenylate to dithiothreitol molecule. 相似文献
59.
Abasic (AP) sites in DNA arise either spontaneously, or through glycosylase-catalyzed excision of damaged bases. Their removal by the base excision repair (BER) pathway avoids their mutagenic and cytotoxic consequences. XRCC1 coordinates and facilitates single-strand break (SSB) repair and BER in mammalian cells. We report that XRCC1, through its NTD and BRCT1 domains, has affinity for several DNA intermediates in BER. As shown by its capacity to form a covalent complex via Schiff base, XRCC1 binds AP sites. APE1 suppresses binding of XRCC1 to unincised AP sites however, affinity was higher when the DNA carried an AP-lyase- or APE1-incised AP site. The AP site binding capacity of XRCC1 is enhanced by the presence of strand interruptions in the opposite strand. Binding of XRCC1 to BER DNA intermediates could play an important role to warrant the accurate repair of damaged bases, AP sites or SSBs, in particular in the context of clustered DNA damage. 相似文献
60.
Water is essential for the stability and functions of proteins and DNA. Reverse micelles are simple model systems where the structure and dynamics of water are controlled. We have estimated the size of complex reverse micelles by light scattering technique and examined the local microenvironment using fluorescein as molecular probe. The micelle size and water polarity inside reverse micelles depend on water volume fraction. We have investigated the different hydration and confinement effects on activity, processivity, and stability of mammalian DNA polymerase β in reverse micelles. The enzyme displays high processivity on primed single-stranded M13mp19 DNA with maximal activity at 10% of water content. The processivity and activity of DNA polymerase strongly depend on the protein concentration. The enzyme reveals also the enhanced stability in the presence of template-primer and at high protein concentration. The data provide direct evidence for strong influence of microenvironment on DNA polymerase activity. 相似文献