全文获取类型
收费全文 | 64949篇 |
免费 | 5098篇 |
国内免费 | 663篇 |
专业分类
70710篇 |
出版年
2023年 | 300篇 |
2022年 | 858篇 |
2021年 | 1347篇 |
2020年 | 854篇 |
2019年 | 1048篇 |
2018年 | 1445篇 |
2017年 | 1222篇 |
2016年 | 1982篇 |
2015年 | 3158篇 |
2014年 | 3580篇 |
2013年 | 4094篇 |
2012年 | 5195篇 |
2011年 | 5048篇 |
2010年 | 3201篇 |
2009年 | 2822篇 |
2008年 | 3887篇 |
2007年 | 3731篇 |
2006年 | 3310篇 |
2005年 | 3091篇 |
2004年 | 2820篇 |
2003年 | 2486篇 |
2002年 | 2188篇 |
2001年 | 1811篇 |
2000年 | 1684篇 |
1999年 | 1406篇 |
1998年 | 597篇 |
1997年 | 534篇 |
1996年 | 423篇 |
1995年 | 370篇 |
1994年 | 352篇 |
1993年 | 289篇 |
1992年 | 566篇 |
1991年 | 535篇 |
1990年 | 462篇 |
1989年 | 438篇 |
1988年 | 361篇 |
1987年 | 314篇 |
1986年 | 274篇 |
1985年 | 273篇 |
1984年 | 203篇 |
1983年 | 182篇 |
1982年 | 153篇 |
1981年 | 150篇 |
1979年 | 178篇 |
1978年 | 142篇 |
1977年 | 120篇 |
1976年 | 111篇 |
1975年 | 130篇 |
1974年 | 151篇 |
1973年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
33.
Secretion of Recombinant Pediocin PA-1 by Bifidobacterium longum, Using the Signal Sequence for Bifidobacterial α-Amylase 下载免费PDF全文
Gi-Seong Moon Yu-Ryang Pyun Myeong Soo Park Geun Eog Ji Wang June Kim 《Applied microbiology》2005,71(9):5630-5632
A recombinant DNA, encoding the chimeric protein of the signal sequence for bifidobacterial α-amylase mature pediocin PA-1, was introduced into Bifidobacterium longum MG1. Biologically active pediocin PA-1 was successfully secreted from the strain and showed bactericidal activity against Listeria monocytogenes and the same molecular mass as native pediocin PA-1. 相似文献
34.
The effect of T-independent (TIA) and T-dependent (IDA) antigens on the surface Ig of 24-hr cultured rabbit spleen cells was investigated by two techniques: the proportion of cells bearing surface Ig was determined by direct rosette formation with anti-light chain allotype-coated erythrocytes; the total amount of surface Ig was estimated by labeling the cells with anti-allotype 125I-labeled Fab fragments. The addition of TIA resulted in the maintenance of the proportion of Ig-bearing cells almost to the initial level, an effect which could not be obtained with any of the TDA tested. The same type of effect was observed when the total amount of surface Ig was measured, i.e., there was a slight reduction (about 24%) in the amount of surface Ig in cultures to which TIAs were added and an almost sixfold reduction (about 70%) in cultures to which TDA, Con A, or no antigen was added. Some but not all of the TIA were able to induce [3H]TdR incorporation in 3-day spleen-cell cultures. We concluded that the common feature of TIA is the ability to stimulate the turnover of B-cell surface Ig, a feature that can be used for an easy screening of TIA. 相似文献
35.
36.
37.
38.
39.
40.
88 rice and 75 soybean samples were collected from 8 provinces of Korea from March through September in 1988. The Fusarium mycotoxins, zearalenone was analyzed by direct competitive enzyme linked immunosorbent assay. 10.2% of rice and 9.3 % of soybean samples contained detectable zearalenone. The average levels of zearalenone of rice and soybean samples were 11.78μg/kg and 7.70μ/kg, respectively. 相似文献