全文获取类型
收费全文 | 15771篇 |
免费 | 1709篇 |
国内免费 | 7篇 |
出版年
2022年 | 108篇 |
2021年 | 314篇 |
2020年 | 163篇 |
2019年 | 214篇 |
2018年 | 236篇 |
2017年 | 218篇 |
2016年 | 374篇 |
2015年 | 603篇 |
2014年 | 659篇 |
2013年 | 838篇 |
2012年 | 1020篇 |
2011年 | 955篇 |
2010年 | 592篇 |
2009年 | 565篇 |
2008年 | 792篇 |
2007年 | 712篇 |
2006年 | 680篇 |
2005年 | 695篇 |
2004年 | 670篇 |
2003年 | 636篇 |
2002年 | 599篇 |
2001年 | 262篇 |
2000年 | 255篇 |
1999年 | 274篇 |
1998年 | 223篇 |
1997年 | 147篇 |
1996年 | 159篇 |
1995年 | 166篇 |
1994年 | 150篇 |
1993年 | 152篇 |
1992年 | 204篇 |
1991年 | 207篇 |
1990年 | 189篇 |
1989年 | 196篇 |
1988年 | 190篇 |
1987年 | 181篇 |
1986年 | 163篇 |
1985年 | 173篇 |
1984年 | 152篇 |
1983年 | 146篇 |
1982年 | 128篇 |
1981年 | 140篇 |
1980年 | 116篇 |
1979年 | 139篇 |
1978年 | 103篇 |
1977年 | 112篇 |
1976年 | 102篇 |
1974年 | 121篇 |
1973年 | 106篇 |
1972年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Demonstration that a chemically synthesized BPV1 oncoprotein and its C-terminal domain function to induce cellular DNA synthesis 总被引:17,自引:0,他引:17
Bovine papillomavirus type 1 contains the smallest known oncogene (ORF E5), encoding a hydrophobic 44 amino acid protein. To study the biochemical functions of the E5 oncoprotein, we have chemically synthesized it and several deletion mutant peptides. We demonstrate induction of cellular DNA synthesis in growth-arrested cells by microinjection of E5 oncoprotein. This activity can be broken down into two functionally distinguishable domains. Remarkably, the first domain, which alone is sufficient to induce cellular DNA synthesis, contains only the C-terminal 13 amino acids. This is the smallest known protein fragment that can autonomously activate cellular DNA synthesis. The second domain is the hydrophobic middle region, which by itself fails to induce cellular DNA synthesis but confers a 1000-fold increase in specific activity. The N-terminal one-third of the molecule is dispensable for induction of DNA synthesis. 相似文献
2.
3.
N. L. Biddington P. A. Brocklehurst A. S. Dearman Jane Dearman 《Physiologia plantarum》1982,55(4):407-410
Celery seeds ( Apium graveolens L.) given a germination induction period (3 days imbibition at 17°C in the light) could be prevented from germinating by up to 14 days subsequent exposure to high temperature (32°C), polyethylene glycol (PEG), abscisic acid (ABA) or dark (22°C). When the seeds were returned to 17°C in the light, germination occurred and, except for the high temperature treatment, was more rapid compared to seeds given a germination induction period only.
Celery seeds incubated for 3 days at 17°C in the light and then air-dried at 20°C germinated slowly when re-sown at 17°C in the light, and achieved only 19% germination after 21 days. Exposing the seeds to high temperature, PEG, ABA or dark for up to 14 days before drying maintained seed viability and subsequent germination was faster. The longer treatment periods gave increased benefit, and PEG was the most effective treatment. It is suggested that the effectiveness of the treatments in inducing dehydration tolerance relates to their ability to inhibit germination possibly via their prevention of cell expansion. 相似文献
Celery seeds incubated for 3 days at 17°C in the light and then air-dried at 20°C germinated slowly when re-sown at 17°C in the light, and achieved only 19% germination after 21 days. Exposing the seeds to high temperature, PEG, ABA or dark for up to 14 days before drying maintained seed viability and subsequent germination was faster. The longer treatment periods gave increased benefit, and PEG was the most effective treatment. It is suggested that the effectiveness of the treatments in inducing dehydration tolerance relates to their ability to inhibit germination possibly via their prevention of cell expansion. 相似文献
4.
5.
6.
7.
Charlotte Gray 《CMAJ》1984,130(6):769-772
9.
A method is described for the subcellular fractionation of goldfish xanthophores. The procedure produces relatively pure fractions of caroteniod droplets, pterinosomes, cytosol and what appears to be plasma membrane. The presence of a distinct pattern of proteins is shown to be associated with the carotenoid droplets. Treatment of the xanthophores with ACTH affects the buoyant density of some carotenoid droplets and stimulates the phosphorylation of a polypeptide associated with the carotenoid droplets. 相似文献