全文获取类型
收费全文 | 11439篇 |
免费 | 170篇 |
国内免费 | 80篇 |
专业分类
系统科学 | 235篇 |
丛书文集 | 179篇 |
教育与普及 | 24篇 |
理论与方法论 | 45篇 |
现状及发展 | 4293篇 |
研究方法 | 446篇 |
综合类 | 6373篇 |
自然研究 | 94篇 |
出版年
2016年 | 77篇 |
2015年 | 86篇 |
2014年 | 70篇 |
2013年 | 69篇 |
2012年 | 250篇 |
2011年 | 386篇 |
2010年 | 65篇 |
2009年 | 68篇 |
2008年 | 162篇 |
2007年 | 194篇 |
2006年 | 161篇 |
2005年 | 346篇 |
2004年 | 859篇 |
2003年 | 727篇 |
2002年 | 486篇 |
2001年 | 368篇 |
2000年 | 434篇 |
1999年 | 304篇 |
1992年 | 178篇 |
1991年 | 170篇 |
1990年 | 146篇 |
1989年 | 141篇 |
1988年 | 135篇 |
1987年 | 137篇 |
1986年 | 143篇 |
1985年 | 194篇 |
1984年 | 147篇 |
1983年 | 120篇 |
1982年 | 98篇 |
1981年 | 127篇 |
1980年 | 125篇 |
1979年 | 308篇 |
1978年 | 234篇 |
1977年 | 212篇 |
1976年 | 162篇 |
1975年 | 194篇 |
1974年 | 260篇 |
1973年 | 218篇 |
1972年 | 241篇 |
1971年 | 269篇 |
1970年 | 322篇 |
1969年 | 273篇 |
1968年 | 244篇 |
1967年 | 249篇 |
1966年 | 233篇 |
1965年 | 180篇 |
1958年 | 104篇 |
1957年 | 76篇 |
1956年 | 73篇 |
1954年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Antidiuretic effects of oxytocin in the Brattleboro rat 总被引:1,自引:0,他引:1
J. Lyness A. G. Robinson M. N. Sheridan D. M. Gash 《Cellular and molecular life sciences : CMLS》1985,41(11):1444-1446
Summary The antidiuretic activity of oxytocin (OT) was measured in Brattleboro rats with congenital diabetes insipidus. A dose dependent antidiuretic response was found in animals receiving chronic infusions of 0.1 g/h, 1.0 g/h, and 5 g/h of OT. OT infused at the rate of 5 g/h over a 7-day period completely reversed the symptoms of diabetes insipidus. The results support the concept that OT serves as a weak agonist of vasopressin at the level of the kidney and at pharmacological levels exhibits antidiuretic activity. 相似文献
62.
Summary Visual determination of MSH-induced pigment migration in melanophores of small pieces ofAnolis carolinensis skin is standardized by first measuring photoelectrometrically the change in reflection/transmission of the whole dorsal skin in response to different hormone concentrations. This method allows the rapid and precise recording of time-response curves after photoaffinity labeling of MSH receptors or of dose-response curves of large series of synthetic compounds.Acknowledgments. We wish to thank Ms V. Jäggin, Ms C. Schulthess and Ms G. van Hees for excellent technical assistance, Dr. R. Andreatta, Ciba-Geigy AG, Basel, for his generous gift of -MSH and Prof. A Pletscher for his continuous interest. This work was supported by the Swiss National Science Foundation. 相似文献
63.
N. Akaike K. Hattori Y. Oomura D. O. Carpenter 《Cellular and molecular life sciences : CMLS》1985,41(1):70-71
Summary Using isolated, internally perfused bullfrog dorsal root ganglion cells we have studied the dose-response curves for -aminobutyric acid (GABA) in the presence of internally or externally applied GABA antagonists. With external application of antagonists the inhibition of the GABA current by bicuculline was competitive and that by picrotoxin was noncompetitive. Picrotoxin but not bicuculline blocked when internally perfused.To whom reprint requests should be addressed.Acknowledgments. We thank Drs S. Minakami and S. Yasui for helpful discussions and comments. 相似文献
64.
Jupiter's ring system has previously been described as being composed of a 'bright' narrow ring and an interior, vertically-extended halo. The one image which reveals this morphology most clearly is Voyager 2's parting shot of the Jupiter system, a wide-angle (WA) view of the ring ansa in forward-scattered light (FDS 20693.02). The bright ring is plainly visible, and the halo appears after slight contrast enhancement. By further enhancement of this image we have discovered an additional ring, which is far fainter than either of the (already faint) components previously identified, extending to a radius of 210,000 km. 相似文献
65.
J. R. Martinez N. Cassity S. Barker 《Cellular and molecular life sciences : CMLS》1987,43(9):1013-1015
Summary The -adrenergic agonist isoproterenol and prostaglandins E1 and E2 (but not F2) increased the cAMP content of rat submandibular acini in vitro, but only isoproterenol enhanced ouabain-sensitive86Rb (K) uptake. These findings suggest that cAMP is not involved in the activation of the Na, K pump in salivary cells. 相似文献
66.
M. Kashimata M. Hiramatsu N. Minami Jr N. Minami 《Cellular and molecular life sciences : CMLS》1987,43(2):191-192
Summary An enzyme immunoassay for mouse epidermal growth factor (EGF) involving a liquid phase double-antibody system was developed. The EGF--galactosidase conjugate prepared was stable for at least 8 months. By this method, EGF was detectable at a concentration as low as 20 pg per tube. The concentrations of EGF in various tissues of mice are also presented.This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan. 相似文献
67.
针对在风速、同步发电机负载变化情况下,液压蓄能式风力机组并网转速控制问题,提出一种新型并网转速控制方法——解耦广义预测优化控制方法(Decoupled Generalized Predictive Optimization Control, DGPOC).首先,DGPOC利用基于广义预测的前馈解耦方法解除变量马达摆角和蓄能器比例阀开度之间的耦合关系,进而调节蓄能器比例阀,依靠蓄能器吸收波动流量,同步调节变量马达摆角实现恒转速控制,解决因风速、同步发电机负载变化引起的变量马达转速波动问题; 其次,将蓄能器比例阀的能量损耗作为性能约束项,加入到优化目标函数中,求取最优控制量,从而提高液压蓄能式风力机组风能利用率; 最后,利用建立的MATLAB-AMESim联合仿真实验平台验证DGPOC方法的有效性.实验结果表明: DGPOC方法不仅可以实现变量马达摆角和蓄能器比例阀开度两个变量的解耦,提升变量马达转速控制的快速性及鲁棒性,而且能够降低系统的能量损耗. 相似文献
68.
Pineal gland changes of rats exposed to heat 总被引:1,自引:0,他引:1
69.
Organizers Abstracts of the th Meeting – September 《Cellular and molecular life sciences : CMLS》1991,47(1):A67-A75
Posters
Protein structure and function 相似文献70.
Summary Metabolism of 26-hydroxycholesterol to 3-hydroxychol-5-en-24-oic acid and other C24-bile acids has been expected to occur by way of 3-hydroxycholest-5-en-26-oic acid in studies in vitro. 3-Hydroxycholest-5-en-26-oic acid was infused intravenously into bile fistula hamsters and the following C24-bile acids were identified: 3-hydroxychol-5-en-24-oic acid, lithocholic acid, chenodeoxycholic acid, and a small amount of cholic acid. 相似文献