全文获取类型
收费全文 | 510篇 |
免费 | 55篇 |
专业分类
565篇 |
出版年
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 24篇 |
2014年 | 31篇 |
2013年 | 31篇 |
2012年 | 43篇 |
2011年 | 31篇 |
2010年 | 23篇 |
2009年 | 15篇 |
2008年 | 33篇 |
2007年 | 19篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 14篇 |
2003年 | 9篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 20篇 |
1999年 | 8篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 6篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1960年 | 3篇 |
排序方式: 共有565条查询结果,搜索用时 0 毫秒
71.
Role of W181 in modulating kinetic properties of Plasmodium falciparum hypoxanthine guanine xanthine phosphoribosyltransferase 下载免费PDF全文
Hypoxanthine‐guanine‐xanthine phosphoribosyltransference (HGXPRT), a key enzyme in the purine salvage pathway of the malarial parasite, Plasmodium falciparum (Pf), catalyses the conversion of hypoxanthine, guanine, and xanthine to their corresponding mononucleotides; IMP, GMP, and XMP, respectively. Out of the five active site loops (I, II, III, III', and IV) in PfHGXPRT, loop III' facilitates the closure of the hood over the core domain which is the penultimate step during enzymatic catalysis. PfHGXPRT mutants were constructed wherein Trp 181 in loop III' was substituted with Ser, Thr, Tyr, and Phe. The mutants (W181S, W181Y and W181F), when examined for xanthine phosphoribosylation activity, showed an increase in Km for PRPP by 2.1‐3.4 fold under unactivated condition and a decrease in catalytic efficiency by more than 5‐fold under activated condition as compared to that of the wild‐type enzyme. The W181T mutant showed 10‐fold reduced xanthine phosphoribosylation activity. Furthermore, molecular dynamics simulations of WT and in silico W181S/Y/F/T PfHGXPRT mutants bound to IMP.PPi.Mg2+ have been carried out to address the effect of the mutation of W181 on the overall dynamics of the systems and identify local changes in loop III'. Dynamic cross‐correlation analyses show a communication between loop III' and the substrate binding site. Differential cross‐correlation maps indicate altered communication among different regions in the mutants. Changes in the local contacts and hydrogen bonding between residue 181 with the nearby residues cause altered substrate affinity and catalytic efficiency of the mutant enzymes. Proteins 2016; 84:1658–1669. © 2016 Wiley Periodicals, Inc. 相似文献
72.
Panigrahi A. Esakkiraj P. Saranya C. Das R. R. Sundaram M. Sudheer N. S. Biju I. F. Jayanthi M. 《Probiotics and antimicrobial proteins》2022,14(2):277-287
Probiotics and Antimicrobial Proteins - Experiments were conducted to evaluate the probiotic effect of bio-augmented Bacillus tequilensis AP BFT3 on improving production, immune response, and... 相似文献
73.
Background
The decrease in cost for sequencing and improvement in technologies has made it easier and more common for the re-sequencing of large genomes as well as parallel sequencing of small genomes. It is possible to completely sequence a small genome within days and this increases the number of publicly available genomes. Among the types of genomes being rapidly sequenced are those of microbial and viral genomes responsible for infectious diseases. However, accurate gene prediction is a challenge that persists for decoding a newly sequenced genome. Therefore, accurate and efficient gene prediction programs are highly desired for rapid and cost effective surveillance of RNA viruses through full genome sequencing. 相似文献74.
Suppressors of a Lin-12 Hypomorph Define Genes That Interact with Both Lin-12 and Glp-1 in Caenorhabditis Elegans 总被引:1,自引:0,他引:1 下载免费PDF全文
The lin-12 gene of Caenorhabditis elegans is thought to encode a receptor which mediates cell-cell interactions required to specify certain cell fates. Reversion of the egg-laying defective phenotype caused by a hypomorphic lin-12 allele identified rare extragenic suppressor mutations in five genes, sel-1, sel-9, sel-10, sel-11 and sel(ar40) (sel = suppressor and/or enhancer of lin-12). Mutations in each of these sel genes suppress defects associated with reduced lin-12 activity, and enhance at least one defect associated with elevated lin-12 activity. None of the sel mutations cause any obvious phenotype in a wild-type background. Gene dosage experiments suggest that sel-1 and sel(ar40) mutations are reduction-of-function mutations, while sel-9 and sel-11 mutations are gain-of-function mutations. sel-1, sel-9, sel-11 and sel(ar40) mutations do not suppress amorphic lin-12 alleles, while sel-10 mutations are able to bypass partially the requirement for lin-12 activity in at least one cell fate decision. sel-1, sel-9, sel-10, sel-11 and sel(ar40) mutations are also able to suppress the maternal-effect lethality caused by a partial loss-of-function allele of glp-1, a gene that is both structurally and functionally related to lin-12. These sel genes may therefore function in both lin-12 and glp-1 mediated cell fate decisions. 相似文献
75.
76.
77.
Kasinathan C Gandhi N Ramaprasad P Sundaram P Ramasubbu N 《International journal of biological sciences》2007,3(4):237-241
Tyrosylprotein sulfotransferase (TPST), responsible for the sulfation of a variety of secretory and membrane proteins, has been identified and characterized in submandibular salivary glands (William et al. Arch Biochem Biophys 1997; 338: 90-96). In the present study we demonstrate the sulfation of a salivary secretory protein, statherin, by the tyrosylprotein sulfotransferase present in human saliva. Optimum statherin sulfation was observed at pH 6.5 and at 20 mm MnCl(2). Increase in the level of total sulfation was observed with increasing statherin concentration. The K(m)value of tyrosylprotein sulfotransferase for statherin was 40 microM. Analysis of the sulfated statherin product on SDS-polyacrylamide gel electrophoresis followed by autoradiography revealed (35)S-labelling of a 5 kDa statherin. Further analysis of the sulfated statherin revealed the sulfation on tyrosyl residue. This study is the first report demonstrating tyrosine sulfation of a salivary secretory protein. The implications of this sulfation of statherin in hydroxyapatite binding and Actinomyces viscosus interactions are discussed. 相似文献
78.
Madhaiyan M Suresh Reddy BV Anandham R Senthilkumar M Poonguzhali S Sundaram SP Sa T 《Current microbiology》2006,53(4):270-276
This study, framed in two different phases, studied the plant-growth promotion and the induction of systemic resistance in
groundnut by Methylobacterium. Seed imbibition with Methylobacterium sp. increased germination by 19.5% compared with controls. Combined inoculation of Methylobacterium sp. with Rhizobium sp. also significantly increased plant growth, nodulation, and yield attributes in groundnut compared with individual inoculation
of Rhizobium sp. Methylobacterium sp. challenge-inoculated with Aspergillus niger/Sclerotium rolfsii in groundnut significantly enhanced germination percentage and seedling vigour and showed increased phenylalanine ammonia
lyase (PAL), β-1,3-glucanase, and peroxidase (PO) activities. Under pot-culture conditions, in Methylobacterium sp. seed—treated groundnut plants challenge-inoculated with A. niger/S. rolfsii through foliar sprays on day 30, the activities of enzymes PO, PAL, and β-1,3-glucanase increased constantly from 24 to 72
hours, after which decreased activity was noted. Five isozymes of polyphenol oxidase and PO could be detected in Methylobacterium-treated plants challenged with A. niger/S. rolfsii. Induced systemic resistance activity in groundnut against rot pathogens in response to methylotrophic bacteria suggests the
possibility that pink-pigmented facultative methylotrophic bacteria might be used as a means of biologic disease control. 相似文献
79.
80.
Coon S Sundaram U 《American journal of physiology. Gastrointestinal and liver physiology》2003,285(6):G1084-G1090
In the rabbit small intestine, there are three functionally different brush-border membrane (BBM) anion/HCO3- exchangers: 1) Cl/HCO3- exchange on the BBM of villus cells responsible for coupled NaCl absorption; 2) Cl/HCO3- exchange on the BBM of crypt cells possibly involved in HCO3- secretion; and 3) short-chain fatty acid (SCFA)/HCO3- exchange on the BBM of villus cells, which facilitates SCFA absorption. Although constitutive nitric oxide (cNO) has been postulated to alter many gastrointestinal tract functions, how cNO may specifically alter these three transporters is unknown. Inhibition of cNO synthase with NG-nitro-L-arginine methyl ester (L-NAME) 1) did not affect villus cell BBM Cl/HCO3 change, 2) stimulated crypt cell BBM Cl/HCO3- exchange, and 3) inhibited villus cell BBM SCFA/HCO3- exchange. D-NAME, an inactive analog of L-NAME, and L-N6-(1-iminoethyl)lysine, a more selective inhibitor of inducible NO, did not affect these transport processes. Kinetic studies demonstrated that 1) the mechanism of inhibition of crypt cell BBM Cl/HCO3- exchange is secondary to a decrease in the maximal rate of uptake of Cl, without an alteration in the affinity of the transporter for Cl, and 2) the mechanism of stimulation of villus cell BBM SCFA/HCO3- exchange is secondary to an increase in the affinity of the transporter for SCFA without an alteration in the maximal rate of uptake of SCFA. These results indicate that cNO uniquely regulates the three BBM anion/HCO3- transporters in the rabbit small intestine. 相似文献