全文获取类型
收费全文 | 5368篇 |
免费 | 479篇 |
国内免费 | 3篇 |
出版年
2023年 | 18篇 |
2022年 | 52篇 |
2021年 | 103篇 |
2020年 | 65篇 |
2019年 | 51篇 |
2018年 | 79篇 |
2017年 | 71篇 |
2016年 | 128篇 |
2015年 | 242篇 |
2014年 | 276篇 |
2013年 | 347篇 |
2012年 | 441篇 |
2011年 | 449篇 |
2010年 | 286篇 |
2009年 | 269篇 |
2008年 | 338篇 |
2007年 | 367篇 |
2006年 | 363篇 |
2005年 | 349篇 |
2004年 | 309篇 |
2003年 | 347篇 |
2002年 | 303篇 |
2001年 | 50篇 |
2000年 | 33篇 |
1999年 | 58篇 |
1998年 | 73篇 |
1997年 | 43篇 |
1996年 | 43篇 |
1995年 | 32篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 29篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有5850条查询结果,搜索用时 31 毫秒
31.
Sophie Seigneurin-Venin Elaine Parrish Isabelle Marty François Rieger Georges Romey Michel Villaz Luis Garcia 《Experimental cell research》1996,223(2):301
The process of myoblast fusion during skeletal myogenesis is calcium regulated. Both dihydropyridine receptor and ryanodine receptor are already present on muscle precursors, at the prefusional stage, before they are required for excitation–contraction coupling. Previous pharmacological studies have shown the need for a special pool of Ca2+associated with the membrane for the fusion process to occur. We hypothesized that this pool of Ca2+is mobilized via a machinery similar to that involved in excitation–contraction coupling. The process of fusion in rat L6 muscle precursors was either totally or partially abolished in the presence of the L-type calcium channel inhibitors SR33557 and nifedipine (half inhibition towards 2 μM), respectively. The inhibition was reversible and dose-dependent. Drugs able to deplete internal calcium stores (caffeine, ryanodine, and thapsigargin) were also tested on the fusion. Both caffeine and thapsigargin drastically inhibited fusion whereas ryanodine had no effect. This suggests that fusion may be controlled by internal pools of Ca2+but that its regulation may be insensitive to ryanodine. We presumed that an early form of the ryanodine receptor may exist, with different pharmacological properties than the adult forms. Indeed, Western blot analysis of pre- and postfusional L6 cells demonstrated the presence, at the prefusional stage, of a transient form of the ryanodine receptor protein with an apparent molecular weight slightly different from those of the classical skeletal and cardiac forms. Taken together, these results support the hypothesis that the fusion process is driven by a mechanism involving both the dihydropyridine receptor (α1 subunit of the L-type Ca2+channel) and the internal stores of Ca2+. The machinery underlying this mechanism might consist of slightly different forms of the classic molecules that in adult muscle ensure excitation–contraction coupling. It remains to be seen, however, whether the mobilization of the internal pool of Ca2+is triggered by the type of mechanism already described in skeletal muscle. 相似文献
32.
33.
34.
35.
The effects of deregulation of NR gene expression on growth and nitrogen metabolism of Nicotiana plumbaginifolia plants 总被引:1,自引:0,他引:1
36.
37.
38.
39.
Isabelle Vercruysse Frans Belpaire Pascal Wynant Dsir L. Massart Alain G. Dupont 《Chirality》1994,6(1):5-10
The influence of a single oral dose of 30 mg nicardipine on the pharmacokinetics of (R)- and (S)-propranolol, given orally as rac-propranolol 80 mg, was studied in 12 healthy volunteers. The plasma concentrations were higher for the (S)-enantiomer than for the (R)-enantiomer. The Clo and the Cl′intr of (S)-propranolol were significantly lower than the Clo and Cl′intr of (R)-propranolol. The unbound fraction of (R)-propranolol was significantly higher than that of (S)-propranolol. Coadministration of nicardipine significantly increased the AUC and Cmax and significantly decreased the Clo and Cl′intr for unbound drug of (R)- and (S)-propranolol. These changes were more important for (R)- than for (S)-propranolol. The protein binding was not altered by nicardipine. The enantioselective effect of nicardipine on the metabolic clearance of propranolol appears to be due to an interaction at the level of the metabolizing enzymes. The effect on blood pressure of rac-propranolol was little affected when nicardipine was coadministered with rac-propranolol, and its bradycardic effect was reduced. © 1994 Wiley-Liss, Inc. 相似文献
40.
Isabelle Chevalot Athanase Visvikis Pierre Nabet Jean-Marc Engasser Annie Marc 《Cytotechnology》1994,16(2):121-129
Recombinant Chinese Hamster Ovary (CHO) cells, engineered for the production of human gamma-glutamyl transferase (GGT), have been grown on Cytodex 1 microcarriers, as aggregates, or as single cells in suspension after adaptation. GGT is a membrane bound enzyme which was not secreted during the culture period. The maximal enzyme activity was found to be directly related to the achieved maximal cell density. Culture of CHO on microcarriers yielded the fastest growth, with a specific growth rate of 0.04 h–1, the highest cell density (near 1.3×106 cells ml–1), and the highest enzyme activity around 300 mU ml–1, which corresponded to a specific cellular level of 20 mU 10–5 cells. GGT could also be produced by growing CHO cells in suspension as single cells or as aggregates. Under these conditions, however, the specific CHO growth rate was significantly slower and the GGT level per cell was divided by a factor 6. Growing CHO cells without microcarriers also resulted in differences in cell metabolism, with a higher conversion yield of glutamine into ammonia, and a higher cell lysis. The catalytic kinetic constants of the enzyme were found identical for the three culture systems. 相似文献