全文获取类型
收费全文 | 3014篇 |
免费 | 261篇 |
国内免费 | 4篇 |
出版年
2023年 | 20篇 |
2022年 | 39篇 |
2021年 | 106篇 |
2020年 | 50篇 |
2019年 | 65篇 |
2018年 | 77篇 |
2017年 | 57篇 |
2016年 | 96篇 |
2015年 | 180篇 |
2014年 | 214篇 |
2013年 | 227篇 |
2012年 | 230篇 |
2011年 | 244篇 |
2010年 | 154篇 |
2009年 | 123篇 |
2008年 | 177篇 |
2007年 | 179篇 |
2006年 | 149篇 |
2005年 | 140篇 |
2004年 | 144篇 |
2003年 | 124篇 |
2002年 | 90篇 |
2001年 | 21篇 |
2000年 | 17篇 |
1999年 | 22篇 |
1998年 | 33篇 |
1997年 | 25篇 |
1996年 | 10篇 |
1995年 | 22篇 |
1994年 | 24篇 |
1993年 | 24篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 4篇 |
排序方式: 共有3279条查询结果,搜索用时 15 毫秒
1.
2.
Danielle E. Haulsee Dewayne A. Fox Matthew W. Breece Tonya M. Clauss Matthew J. Oliver 《PloS one》2016,11(2)
We developed a long-term tagging method that can be used to understand species assemblages and social groupings associated with large marine fishes such as the Sand Tiger shark Carcharias taurus. We deployed internally implanted archival VEMCO Mobile Transceivers (VMTs; VEMCO Ltd. Nova Scotia, Canada) in 20 adult Sand Tigers, of which two tags were successfully recovered (10%). The recovered VMTs recorded 29,646 and 44,210 detections of telemetered animals respectively. To our knowledge, this is the first study to demonstrate a method for long-term (~ 1 year) archival acoustic transceiver tag implantation, retention, and recovery in a highly migratory marine fish. Results show low presumed mortality (n = 1, 5%), high VMT retention, and that non-lethal recovery after almost a year at liberty can be achieved for archival acoustic transceivers. This method can be applied to study the social interactions and behavioral ecology of large marine fishes. 相似文献
3.
4.
5.
6.
7.
8.
Characterization and cDNA cloning of phospholipase C-gamma, a major substrate for heparin-binding growth factor 1 (acidic fibroblast growth factor)-activated tyrosine kinase. 总被引:27,自引:5,他引:22
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
W H Burgess C A Dionne J Kaplow R Mudd R Friesel A Zilberstein J Schlessinger M Jaye 《Molecular and cellular biology》1990,10(9):4770-4777
Heparin-binding growth factors (HBGFs) bind to high-affinity cell surface receptors which possess intrinsic tyrosine kinase activity. A Mr 150,000 protein phosphorylated on tyrosine in response to class 1 HBGF (HBGF-1) was purified and partially sequenced. On the basis of this sequence, cDNA clones were isolated from a human endothelial cell library and identified as encoding phospholipase C-gamma. Phosphorylation of phospholipase C-gamma in intact cells treated with HBGF-1 was directly demonstrated by using antiphospholipase C-gamma antibodies. Thus, HBGF-1 joins epidermal growth factor and platelet-derived growth factor, whose receptor activation leads to tyrosine phosphorylation and probable activation of phospholipase C-gamma. 相似文献
9.
Danielle L. Laval-Martin Isabelle A. Carr Saverio J. Barbera Leland N. Edmunds 《Chronobiology international》1990,7(2):99-105
-We have previously shown that NAD kinase and NADP phosphatase activities display circadian rhythms, in the soluble (SN) and membrane-bound (P) fractions of crude extracts of the achlorophyllous ZC mutant of the phytoflagellate Euglena gracilis (which displays circadian rhythmicity of cell division). We determined if changes in the affinity of NADP phosphatase and NAD kinase for their substrates, NADP+ and NAD+, were occurring by calculating the ratios 100(velocity found in Km conditions/velocity found in saturating conditions). The rationale was that if the affinity remained unchanged according to circadian time (CI), these values should always equal 50, independently of any changes in enzyme quantity; values greater than 50 should indicate increases in enzyme affinity, and values less than 50 decreases in affinity. Our results indicated that these values calculated for NADP phosphatase exhibited a complex pattern of rhythmicity, while those for NAD kinase displayed circadian variations strongly correlated with the rhythms in enzyme activity. The curves showed troughs at CT 00-04 both in dividing and nondividing cells and peaks at CT 18-20 or at CT 08-14 in cells sampled, respectively, from a dividing or a stationary culture. Such variations are indicative of changes in the kinetic properties of the enzyme, which may reflect modifications in its affinity either for effectors (such as Ca2+-calmodulin) or for its substrate, NAD+. This may be due to (i) the expression of different isoenzymes at different CTs; (ii) different posttranslational modifications of the enzyme; or (iii) concentrations of effectors varying in a circadian manner. 相似文献
10.
A simple procedure is described for the determination of the photosensitizing potency of drugs, using three leukemic cell lines, two of lymphocytic origin, L1210 and P388 and one of erythroid type, Friend-745. The procedure allows one to investigate several aspects of the photosensitization properties of tested compounds such as cellular localization and direct (trypan blue exclusion) or delayed (clonogenicity) photomediated toxicities.The method was assessed using crude hematoporphyrin derivative (HPD) as well as dihematoporphyrin ether (DHE) or commercially available Photofrin II. Results were compared to those obtained with normal cells, e.g spleen lymphocytes and erythropoietic stem cells (CFU-e), and discussed in the light of the relative response of normal versus transformed cells.Abbreviations DHE
Dihematoporphyrin Ether
- FCS
Fetal Calf Serum
- HPD
Hematoporphyrin Derivative
- PDT
Photodynamic Therapy 相似文献