全文获取类型
收费全文 | 1020篇 |
免费 | 79篇 |
出版年
2022年 | 11篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 16篇 |
2017年 | 4篇 |
2016年 | 18篇 |
2015年 | 40篇 |
2014年 | 31篇 |
2013年 | 68篇 |
2012年 | 48篇 |
2011年 | 64篇 |
2010年 | 31篇 |
2009年 | 37篇 |
2008年 | 49篇 |
2007年 | 44篇 |
2006年 | 40篇 |
2005年 | 43篇 |
2004年 | 41篇 |
2003年 | 52篇 |
2002年 | 30篇 |
2001年 | 31篇 |
2000年 | 34篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 10篇 |
1992年 | 31篇 |
1991年 | 12篇 |
1990年 | 25篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1972年 | 3篇 |
排序方式: 共有1099条查询结果,搜索用时 171 毫秒
331.
Matthew J. Ranaghan Ramasamy P. Kumar Kalyan S. Chakrabarti Vanessa Buosi Dorothee Kern Daniel D. Oprian 《The Journal of biological chemistry》2013,288(50):36160-36167
Recoverin, a 23-kDa Ca2+-binding protein of the neuronal calcium sensing (NCS) family, inhibits rhodopsin kinase, a Ser/Thr kinase responsible for termination of photoactivated rhodopsin in rod photoreceptor cells. Recoverin has two functional EF hands and a myristoylated N terminus. The myristoyl chain imparts cooperativity to the Ca2+-binding sites through an allosteric mechanism involving a conformational equilibrium between R and T states of the protein. Ca2+ binds preferentially to the R state; the myristoyl chain binds preferentially to the T state. In the absence of myristoylation, the R state predominates, and consequently, binding of Ca2+ to the non-myristoylated protein is not cooperative. We show here that a mutation, C39A, of a highly conserved Cys residue among NCS proteins, increases the apparent cooperativity for binding of Ca2+ to non-myristoylated recoverin. The binding data can be explained by an effect on the T/R equilibrium to favor the T state without affecting the intrinsic binding constants for the two Ca2+ sites. 相似文献
332.
Alpana Ray Mohamed Alalem Bimal K. Ray 《The Journal of biological chemistry》2013,288(38):27232-27242
333.
The bacterial community structure of a municipal landfill in Chandigarh, India was analysed by culture-dependent as well as culture-independent molecular approaches, and archaeal structure by the latter method. Samples were collected in two phases from the surface and a depth of 0.91 m in June, 2004 and from 0.91 m, 1.52 m and 1.68 m in May, 2005. After serial dilutions, samples were plated onto tryptic soy agar (TSA), plate count agar (PCA), tryptic soy broth agar (TSBA) and TSBA100 (TSBA diluted 100 times and solidified with agarose), and incubated aerobically at 30 °C. The number of bacteria (CFU) on different media ranged between 9.4 × 105 g−1 (on PCA) and 1.9 × 107 g−1 (on TSA) (wet weight). The numbers of bacteria enumerated from plates incubated anaerobically (anaerobic agar and reinforced clostridial agar) were 2.1 × 107 and 1.7 × 106 g−1, respectively. Of the 468 isolated and purified bacteria (183 in the first phase and 285 in the second phase), 135 were characterised using phenotypic characteristics as well as 16S rRNA gene sequence analysis. It was found that members of the phylum Firmicutes were overwhelmingly predominant (86.6%) in the landfill, followed by Actinobacteria (9.6%) and Proteobacteria (3.7%). Among the Firmicutes, at least 17 species from the single genus Bacillus were the most abundant inhabitants of the landfill. Detailed polyphasic characterisation of many of these isolates led to the discovery of a novel genus Paenisporosarcina (and the species P. quisquiliarum), a novel species of Microbacterium, M. immunditiarum, and reclassification of Sporosarcina macmurdoensis, Pelagibacillus goriensis, Bacillus silvestris, Bacillus insolitus, Bacillus psychrotolerans and Bacillus psychrodurans. Culture-independent analysis of two 16S rRNA gene libraries also revealed that the phylum Firmicutes was the predominant group in this community. The diversity of Archaea was found to be limited mainly to members of two orders: Methanosarcinales and Methanomicrobiales of the phylum Euryarchaeota. When these results were compared to those reported earlier on similar studies, it was found that irrespective of differences in composition of municipal solid waste (especially compostable organic matter and paper) and climate, the members of bacterial and archaeal communities in landfills of many countries remained broadly similar. 相似文献
334.
335.
Abstract Various amino acid similarity matrices have been derived using data on physicochemical properties and molecular evolution. Conformational similarity indices, CSXX′, between different residues are computed here using the distribution of the main-chain and side-chain torsion angles and the values have been used to cluster amino acids in proteins. A subset of these parameters, CSAX′ indicates the extent of similarity in the main-chain and side-chain conformations (φ ψ and χ1) of different residues (X) with Ala (A) and is found to have strong correlation with α-helix propensities. However, no subset of CSXX′ provides any linear relationship with β-sheet propensities, suggesting that the conformational feature favouring the location of a residue in an a-helix is different from the one favouring the β-sheet. Conformationally similar residues (close CSAX values) have similar steric framework of the side-chain (linear/branched, aliphatic/aromatic), irrespective of the polarity or hydrophobicity. Cooperative nucleation of helix may be facile for a contiguous stretch of residues with high overall CSAX values. 相似文献
336.
B. P. Mukhopadhyay B. Ghosh H. R. Bairagya T. K. Nandi B. Chakrabarti A. K. Bera 《Journal of biomolecular structure & dynamics》2013,31(5):543-551
Abstract The metabolism of Thiobacillus ferrooxidans involves electron transfer from the Fe+2 ions in the extracellular environment to the terminal oxygen in the bacterial cytoplasm through a series of periplasmic proteins like Rusticyanin (RCy), Cytochrome (Cyt c4), and Cytochrome oxidase (CcO). The energy minimization and MD studies reveal the stabilization of the three redox proteins in their ternary complex through the direct and water mediated H-bonds and electrostatic interaction. The surface exposed polar residues of the three proteins, i.e., RCy (His 143, Thr 146, Lys 81, Glu 20), Cyt c4 (Asp 5, 15, 52, Ser 14, Glu 61), and CcO (Asp 135, Glu 126, 140, 142, Thr 177) formed the intermolecular hydrogen bonds and stabilized the ternary complex. The oxygen (Oεl) of Glu 126, 140, and 142 on subunit II of the CcO interact to the exposed side-chain and Ob atoms of the Asp 52 of Cyt c4 and Glu 20 and Leu 12 of RCy. The Asp 135 of subunit II also forms H-bond with the Nε atom of Lys 81 of RCy. The Oεl of Glu 61 of Cyt c4 is also H-bonded to Oγ atom of Thr 177 of CcO. Solvation followed by MD studies of the ternary protein complex revealed the presence of seven water molecules in the interfacial region of the interacting proteins. Three of the seven water molecules (W 79, W 437, and W 606) bridged the three proteins by forming the hydrogen bonded network (with the distances ~ 2.10–2.95 Å) between the Lys 81 (RCy), Glu 61 (Cyt c4), and Asp 135 (CcO). Another water molecule W 603 was H-bonded to Tyr 122 (CcO) and interconnected the Lys 81 (RCy) and Asp 135 (CcO) through the water molecules W 606 and W 437. The other two water molecules (W 21 and W 455) bridged the RCy to Cyt c4 through H-bonds, whereas the remaining W 76 interconnected the His 53 (Cytc4) to Glu 126 (CcO) with distances ~ 2.95–3.0 Å. 相似文献
337.
Kaustav Majumder Subhadeep Chakrabarti Jude S. Morton Sareh Panahi Susan Kaufman Sandra T. Davidge Jianping Wu 《PloS one》2013,8(11)
Background
There is a growing interest in using functional food components as therapy for cardiovascular diseases such as hypertension. We have previously characterized a tri-peptide IRW (Ile-Arg-Trp) from egg white protein ovotransferrin; this peptide showed anti-inflammatory, anti-oxidant and angiotensin converting enzyme (ACE) inhibitor properties in vitro. Given the pathogenic roles played by angiotensin, oxidative stress and inflammation in the spontaneously hypertensive rat (SHR), we tested the therapeutic potential of IRW in this well-established model of hypertension.Methods and Results
16–17 week old male SHRs were orally administered IRW at either a low dose (3 mg/Kg BW) or a high dose (15 mg/Kg BW) daily for 18 days. Blood pressure (BP) and heart rate were measured by telemetry. Animals were sacrificed at the end of the treatment for vascular function studies and measuring markers of inflammation. IRW treatment attenuated mean BP by ~10 mmHg and ~40 mmHg at the low- and high-dose groups respectively compared to untreated SHRs. Heart rate was not affected. Reduction in BP was accompanied by the restoration of diurnal variations in BP, preservation of nitric oxide dependent vasorelaxation, as well as reduction of plasma angiotensin II, other inflammatory markers and tissue fibrosis.Conclusion
Our results demonstrate anti-hypertensive effects of IRW in vivo likely mediated through ACE inhibition, endothelial nitric oxide synthase and anti-inflammatory properties. 相似文献338.
339.
Kaur Harsimran Shankarnarayana Shamanth A. Hallur Vinaykumar Muralidharan Jayashree Biswal Manisha Ghosh Anup K. Ray Pallab Chakrabarti Arunaloke Rudramurthy Shivaprakash M. 《Mycopathologia》2020,185(2):257-268
Mycopathologia - A sudden rise of Candida krusei candidemia cases was noticed in our hospital within 1 year with maximum cases from paediatric unit. The present study reports the results... 相似文献
340.
Chung Ill Min Paudel Niroj Kim Seung-Hyun Yu Chang Yeon Ghimire Bimal Kumar 《Journal of Plant Growth Regulation》2020,39(2):954-954
Journal of Plant Growth Regulation - The original version of this article unfortunately contained an error in Acknowledgement. The authors would like to correct the error with this erratum. The... 相似文献