全文获取类型
收费全文 | 87573篇 |
免费 | 6185篇 |
国内免费 | 5016篇 |
专业分类
98774篇 |
出版年
2024年 | 188篇 |
2023年 | 1521篇 |
2022年 | 2264篇 |
2021年 | 2940篇 |
2020年 | 2834篇 |
2019年 | 3902篇 |
2018年 | 3368篇 |
2017年 | 2482篇 |
2016年 | 2478篇 |
2015年 | 3045篇 |
2014年 | 5550篇 |
2013年 | 6802篇 |
2012年 | 4277篇 |
2011年 | 5520篇 |
2010年 | 4310篇 |
2009年 | 4707篇 |
2008年 | 4797篇 |
2007年 | 4738篇 |
2006年 | 4310篇 |
2005年 | 3766篇 |
2004年 | 3361篇 |
2003年 | 2756篇 |
2002年 | 2396篇 |
2001年 | 1644篇 |
2000年 | 1328篇 |
1999年 | 1302篇 |
1998年 | 1297篇 |
1997年 | 1043篇 |
1996年 | 930篇 |
1995年 | 868篇 |
1994年 | 815篇 |
1993年 | 666篇 |
1992年 | 673篇 |
1991年 | 522篇 |
1990年 | 463篇 |
1989年 | 388篇 |
1988年 | 317篇 |
1987年 | 303篇 |
1986年 | 259篇 |
1985年 | 387篇 |
1984年 | 538篇 |
1983年 | 418篇 |
1982年 | 439篇 |
1981年 | 326篇 |
1980年 | 274篇 |
1979年 | 265篇 |
1978年 | 235篇 |
1977年 | 170篇 |
1976年 | 152篇 |
1974年 | 130篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
Colin K.W. Watts Robert L. Sutherland 《Biochemical and biophysical research communications》1984,120(1):109-115
Saturation and competitive binding analyses demonstrated the presence of a high affinity (KD = 0.92 nM), specific antiestrogen binding site (AEBS) in rat liver microsomes and at least 75% of total liver AEBS was recovered in this fraction. When microsomes were further separated into smooth and rough fractions, AEBS was concentrated in the latter. Subsequent dissociation of ribosomes from the rough membranes revealed that AEBS was associated with the membrane and not the ribosomal fraction. Antiestrogen binding activity could not be extracted from membranes with 1 M KCl or 0.5 M acetic acid but could be solubilized with sodium cholate. These data indicate that AEBS is an integral membrane component of the rough microsomal fraction of rat liver. 相似文献
54.
《Bioorganic & medicinal chemistry》2016,24(2):240-246
A novel series of indolylthiosemicarbazides (6a–6g) and their cyclization products, 4-thiazolidinones (7a–7g), have been designed, synthesized and evaluated, in vitro, for their antiviral activity against a wide range of DNA and RNA viruses. Compounds 6a, 6b, 6c and 6d exhibited notable antiviral activity against Coxsackie B4 virus, at EC50 values ranging from 0.4 to 2.1 μg/mL. The selectivity index (ratio of cytotoxic to antivirally effective concentration) values of these compounds were between 9 and 56. Besides, 6b, 6c and 6d also inhibited the replication of two other RNA viruses, Sindbis virus and respiratory syncytial virus, although these EC50 values were higher compared to those noted for Coxsackie B4 virus. The SAR analysis indicated that keeping the free thiosemicarbazide moiety is crucial to obtain this antiviral activity, since the cyclization products (7a–7g) did not produce any antiviral effect. 相似文献
55.
56.
57.
58.
A bacterial clone carrying sequences coding for elongation factor EF-1 alpha from Artemia 总被引:2,自引:0,他引:2
A bacterial cDNA clone was identified carrying one third of the nucleotides coding for elongation factor EF-1 alpha from the brine shrimp Artemia. The sequence of codons corresponds with the known sequence of amino acids of EF-1 alpha in the region involved. 相似文献
59.
Charles E. Wenner John C. Cheney L. David Tomei 《Journal of cellular biochemistry》1981,15(2):161-168
The introduction of either PGF2α (10?7 M) or TPA (10?7 M) stimulated, ouabain-sensitive 86Rb+ influx at 30 min in postconfluent 3T3-4 mouse fibroblast cultures by 117% and 124%, respectively. Both TPA and PGF2α at these concentrations stimulated the incorporation of 3H-TdR into DNA. TPA had the greatest stimulatory effect, which was similar to that obtained with 10% fetal calf serum. In accord with the idea that modulation of membrane processes such as Na+/K+ pump activity in fibroblasts may reflect important events related to the initiation of DNA synthesis, it was observed that in both 3T3-4 and C3H-1 0T½ cells there were parallel increases in 3H-TdR incorporation and ouabain-sensitive 86Rb+ influxes with 10?7 M TPA, whereas PGF2α stimulated a significant increase in 3H-TdR incorporation in 3T3-4 but not C3H-10T½ cells and only marginal increases in ouabain-sensitive 86Rb+ influx in both. Therefore, although there appears to be a close correlation between Na+/K+ pump activation and subsequent S-phase entry following TPA stimulation, a similar correlation for PGF2α cannot be confirmed. 相似文献
60.