全文获取类型
收费全文 | 826篇 |
免费 | 106篇 |
出版年
2022年 | 4篇 |
2021年 | 19篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 20篇 |
2016年 | 28篇 |
2015年 | 41篇 |
2014年 | 53篇 |
2013年 | 49篇 |
2012年 | 62篇 |
2011年 | 52篇 |
2010年 | 23篇 |
2009年 | 36篇 |
2008年 | 55篇 |
2007年 | 48篇 |
2006年 | 33篇 |
2005年 | 41篇 |
2004年 | 32篇 |
2003年 | 32篇 |
2002年 | 29篇 |
2001年 | 13篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1969年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有932条查询结果,搜索用时 15 毫秒
121.
Ursula Pieper Narayanan Eswar Ashley C. Stuart Valentin A. Ilyin Andrej Sali 《Nucleic acids research》2002,30(1):255-259
MODBASE (http://guitar.rockefeller.edu/modbase) is a relational database of annotated comparative protein structure models for all available protein sequences matched to at least one known protein structure. The models are calculated by MODPIPE, an automated modeling pipeline that relies on PSI-BLAST, IMPALA and MODELLER. MODBASE uses the MySQL relational database management system for flexible and efficient querying, and the MODVIEW Netscape plugin for viewing and manipulating multiple sequences and structures. It is updated regularly to reflect the growth of the protein sequence and structure databases, as well as improvements in the software for calculating the models. For ease of access, MODBASE is organized into different datasets. The largest dataset contains models for domains in 304 517 out of 539 171 unique protein sequences in the complete TrEMBL database (23 March 2001); only models based on significant alignments (PSI-BLAST E-value < 10–4) and models assessed to have the correct fold are included. Other datasets include models for target selection and structure-based annotation by the New York Structural Genomics Research Consortium, models for prediction of genes in the Drosophila melanogaster genome, models for structure determination of several ribosomal particles and models calculated by the MODWEB comparative modeling web server. 相似文献
122.
123.
124.
125.
Saba Naz Shruti Dabral Sathya Narayanan Nagarajan Divya Arora Lakshya Veer Singh Pradeep Kumar Yogendra Singh Dhiraj Kumar Umesh Varshney Vinay Kumar Nandicoori 《PLoS pathogens》2021,17(3)
Tuberculosis caused by Mycobacterium tuberculosis (Mtb) is a significant public health concern, exacerbated by the emergence of drug-resistant TB. To combat the host’s dynamic environment, Mtb encodes multiple DNA repair enzymes that play a critical role in maintaining genomic integrity. Mtb possesses a GC-rich genome, rendering it highly susceptible to cytosine deaminations, resulting in the occurrence of uracils in the DNA. UDGs encoded by ung and udgB initiate the repair; hence we investigated the biological impact of deleting UDGs in the adaptation of pathogen. We generated gene replacement mutants of uracil DNA glycosylases, individually (RvΔung, RvΔudgB) or together (RvΔdKO). The double KO mutant, RvΔdKO exhibited remarkably higher spontaneous mutation rate, in the presence of antibiotics. Interestingly, RvΔdKO showed higher survival rates in guinea pigs and accumulated large number of SNPs as revealed by whole-genome sequence analysis. Competition assays revealed the superior fitness of RvΔdKO over Rv, both in ex vivo and in vivo conditions. We propose that compromised DNA repair results in the accumulation of mutations, and a subset of these drives adaptation in the host. Importantly, this property allowed us to utilize RvΔdKO for the facile identification of drug targets. 相似文献
126.
127.
128.
Germination studies were carried out with the wheat varieties NP823, Karchia, Sonora 63, Sonora 64, Mayo 64 and Lerma Rojo in artificially salinized soil maintained at ECe 2, 8, 12 and 16 mmhos/cm at 25°C. Early seedling growth and metabolism of variety NP 823 was studied in salt solutions alone and with addition of the growth regulators GA3 and Cycocel (2-chloroethyl trimethylammonium chloride). Soil salinity both depressed and delayed the germination. Among the varieties tested NP 823 and Karchia were relatively less susceptible to salt injury while Lerma Rojo exhibited a maximum susceptibility. Salt supply also brought about a reduction in the early seedling growth, the release of reducing sugar and the amylase activity. The adverse effect on amylase activity was not mediated through the synthesis of enzyme protein but by an inhibition of the enzyme activity. Exogenous supply of GA3 counteracted the adverse effect of salt on amylase activity and the release of reducing sugar but not on the early seedling growth. 相似文献
129.
Christine A. Armstrong George D. Jones Rhona Anderson Pooja Iyer Deepan Narayanan Jatinderpal Sandhu Rajinder Singh Christopher J. Talbot Cristina Tufarelli 《Epigenetics》2012,7(8):892-902
The ability of ionizing radiation to initiate genomic instability has been harnessed in the clinic where the localized delivery of controlled doses of radiation is used to induce cell death in tumor cells. Though very effective as a therapy, tumor relapse can occur in vivo and its appearance has been attributed to the radio-resistance of cells with stem cell-like features. The molecular mechanisms underlying these phenomena are unclear but there is evidence suggesting an inverse correlation between radiation-induced genomic instability and global hypomethylation. To further investigate the relationship between DNA hypomethylation, radiosensitivity and genomic stability in stem-like cells we have studied mouse embryonic stem cells containing differing levels of DNA methylation due to the presence or absence of DNA methyltransferases. Unexpectedly, we found that global levels of methylation do not determine radiosensitivity. In particular, radiation-induced delayed genomic instability was observed at the Hprt gene locus only in wild-type cells. Furthermore, absence of Dnmt1 resulted in a 10-fold increase in de novo Hprt mutation rate, which was unaltered by radiation. Our data indicate that functional DNMTs are required for radiation-induced genomic instability, and that individual DNMTs play distinct roles in genome stability. We propose that DNMTS may contribute to the acquirement of radio-resistance in stem-like cells. 相似文献