全文获取类型
收费全文 | 12346篇 |
免费 | 941篇 |
国内免费 | 3篇 |
出版年
2022年 | 57篇 |
2021年 | 117篇 |
2020年 | 88篇 |
2019年 | 104篇 |
2018年 | 229篇 |
2017年 | 234篇 |
2016年 | 351篇 |
2015年 | 492篇 |
2014年 | 535篇 |
2013年 | 668篇 |
2012年 | 920篇 |
2011年 | 934篇 |
2010年 | 541篇 |
2009年 | 440篇 |
2008年 | 727篇 |
2007年 | 691篇 |
2006年 | 688篇 |
2005年 | 664篇 |
2004年 | 578篇 |
2003年 | 535篇 |
2002年 | 490篇 |
2001年 | 235篇 |
2000年 | 244篇 |
1999年 | 192篇 |
1998年 | 77篇 |
1997年 | 65篇 |
1996年 | 60篇 |
1995年 | 60篇 |
1994年 | 55篇 |
1993年 | 51篇 |
1992年 | 84篇 |
1991年 | 90篇 |
1990年 | 63篇 |
1989年 | 90篇 |
1988年 | 84篇 |
1987年 | 75篇 |
1986年 | 69篇 |
1985年 | 79篇 |
1984年 | 73篇 |
1983年 | 73篇 |
1982年 | 71篇 |
1981年 | 62篇 |
1979年 | 56篇 |
1978年 | 53篇 |
1976年 | 62篇 |
1975年 | 57篇 |
1974年 | 88篇 |
1973年 | 58篇 |
1972年 | 56篇 |
1971年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Erwan Stephan Stéphane Delanaud Cécile Bisch Jean-Pierre Libert Frédéric Telliez 《Journal of electromyography and kinesiology》2008,18(1):160-168
We present here a new, dedicated mechanical device for monitoring quick-release movements of the wrist. The ergometer was designed to easily assess musculotendinous properties during wrist flexion. Maximal voluntary contractions (MVC) and quick-release (QR) movements during wrist flexion were performed on 14 subjects. A validation of the ergometer, using a test-retest methodology, was performed to assess its reliability and sensitivity. The device has been technically and biomechanically validated in a range of situations, including inertia measurement (mean inertia was found 0.0119+/-0.0012 N m s(2) rad(-1)) and appearance of the unloading reflex. Our results indicate that the device provides highly reliable, sensitive evaluation of wrist muscle stiffness (intraclass correlation coefficient for inertia, maximal voluntary contraction and stiffness index were 0.873, 0.994 and 0.930, respectively). Its portability facilitates measurement of the influence of repetitive, occupational activity on the musculotendinous complex of the wrist flexors. 相似文献
5.
6.
J Stürzebecher 《Folia haematologica (Leipzig, Germany : 1928)》1982,109(1):83-88
Structure-activity relationships for the inhibition of thrombin and trypsin by N alpha-substituted amidinophenyl-alpha-aminoalkylcarboxylic acid amides are presented. Secondary cyclic amides of N alpha-substituted 4-amidinophenylalanine and 2-amino-5-(4-amidinophenyl)valeric acid were found to be potent and specific inhibitors of thrombin, whereas trypsin was inhibited strongly by primary amides of 2-amino-4-(4-amidinophenyl) butyric acid. For this type of inhibitor the carbon amide structure seems to play a decisive role in the enzyme-inhibitor interaction. 相似文献
7.
8.
The production of L-lysine fromDL-α-amino-ε-caprolactam (DL-ACL) by new strains producingL-α-amino-ε-caprolactamase and aminocaprolactam racemase is described. Optimal conditions for hydrolysis ofL-ACL byCryptococcus sp. and for racemization of ACL by cells of a strain isolated in nature and identified asPseudomonas sp. were determined. Synthesis ofL-α-amino-ε-caprolactamase is induced byDL-ACL orL-lysine with the same effectivity. A positive effect of phosphates (potassium salts) on reduction of the induction lag was
detected, the synthesis of this enzyme was found to be repressed by glucose and some possibilities of the reversion of this
repressive effect were demonstrated. Under conditions optimal for the production of both enzymes a quantitative theoretical
conversion of 10 % aqueousDL-ACL toL-lysine by a mixture of native cells in a mass ratio of 1: 2 (producer of ACL-hydrolase to producer of ACL-racemase) occurred
in 8 h at 40 °C and pH 8.0 相似文献
9.
A. Klockow-Beck A. Nick St. Geisshuesler D. Schaufelberger 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,720(1-2):141-151
A capillary electrophoresis (CE) method has been developed as an alternative method for the determination of the inorganic degradation products sulfate and sulfamate in topiramate drug product and drug substance, currently performed by ion chromatography. The anions are separated in a background electrolyte containing potassium chromate and boric acid, followed by indirect UV detection. By adding tetradecyltrimethylammonium bromide to the electrolyte, analysis is performed under co-electroosmotic flow conditions. Variations in injection volumes and migration times are compensated for by use of an internal standard. The validation of the method, which was performed according to ICH guidelines (International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) [1], comprises specificity, accuracy, linearity, precision, sensitivity and robustness. In addition, the results of an actual tablet sample analysis obtained by this CE method are statistically shown to be in close agreement with those obtained by an ion chromatographic method. 相似文献
10.