全文获取类型
收费全文 | 269篇 |
免费 | 39篇 |
出版年
2020年 | 3篇 |
2019年 | 6篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 23篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 28篇 |
2009年 | 30篇 |
2008年 | 11篇 |
2007年 | 4篇 |
2006年 | 14篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1970年 | 2篇 |
1969年 | 5篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 4篇 |
1964年 | 1篇 |
1959年 | 1篇 |
1939年 | 3篇 |
1938年 | 2篇 |
1934年 | 2篇 |
排序方式: 共有308条查询结果,搜索用时 15 毫秒
301.
302.
303.
304.
305.
306.
307.
T lymphocytes recognize antigen only after a series of intracellular events known as antigen processing. The result of antigen processing is the production of short segments of the primary peptide sequence bound to a polypeptide-binding groove on major histocompatibility complex (MHC) molecules. Antigen originates from one of two sites: intracellular or extracellular. There are two corresponding pathways for antigen processing and two corresponding classes of MHC molecule. Analysis of each pathway has demonstrated that their separation is not purely anatomical, but is maintained by molecular interactions with other molecules. Antigen processing has been shown to regulate the overall immune response, but the mechanisms involved remain obscure. 相似文献
308.
Seungdae Oh Madan Tandukar Spyros G. Pavlostathis Patrick S. G. Chain Konstantinos T. Konstantinidis 《Environmental microbiology》2013,15(10):2850-2864
Quaternary ammonium compounds (QACs) represent widely used cationic biocides that persist in natural environments. Although microbial degradation, sensitivity and resistance to QACs have been extensively documented, a quantitative understanding of how whole communities adapt to QAC exposure remain elusive. To gain insights into these issues, we exposed a microbial community from a contaminated river sediment to varied levels of benzalkonium chlorides (BACs, a family of QACs) for 3 years. Comparative metagenomic analysis showed that the BAC‐fed communities were dramatically decreased in phylogenetic diversity compared with the control (no BAC exposure), resulting presumably from BAC toxicity, and dominated by Pseudomonas species (> 50% of the total). Time‐course metagenomics revealed that community adaptation occurred primarily via selective enrichment of BAC‐degrading Pseudomonas populations, particularly P. nitroreducens, and secondarily via amino acid substitutions and horizontal transfer of a few selected genes in the Pseudomonas populations, including a gene encoding a PAS/PAC sensor protein and ring‐hydroxylating dioxygenase genes. P. nitroreducens isolates were reproducibly recoverable from communities after prolonged periods of no‐BAC exposure, suggesting that they are robust BAC‐degraders. Our study provides new insights into the mechanisms and tempo of microbial community adaptation to QAC exposure and has implications for treating QACs in biological engineered systems. 相似文献