全文获取类型
收费全文 | 11423篇 |
免费 | 264篇 |
国内免费 | 1篇 |
专业分类
11688篇 |
出版年
2021年 | 84篇 |
2020年 | 81篇 |
2019年 | 94篇 |
2018年 | 229篇 |
2017年 | 198篇 |
2016年 | 269篇 |
2015年 | 254篇 |
2014年 | 334篇 |
2013年 | 438篇 |
2012年 | 409篇 |
2011年 | 439篇 |
2010年 | 274篇 |
2009年 | 208篇 |
2008年 | 298篇 |
2007年 | 323篇 |
2006年 | 327篇 |
2005年 | 296篇 |
2004年 | 248篇 |
2003年 | 299篇 |
2002年 | 258篇 |
2001年 | 280篇 |
2000年 | 220篇 |
1999年 | 175篇 |
1998年 | 83篇 |
1992年 | 230篇 |
1991年 | 220篇 |
1990年 | 178篇 |
1989年 | 210篇 |
1988年 | 230篇 |
1987年 | 235篇 |
1986年 | 213篇 |
1985年 | 240篇 |
1984年 | 195篇 |
1983年 | 160篇 |
1980年 | 82篇 |
1979年 | 228篇 |
1978年 | 152篇 |
1977年 | 133篇 |
1976年 | 134篇 |
1975年 | 165篇 |
1974年 | 261篇 |
1973年 | 258篇 |
1972年 | 249篇 |
1971年 | 241篇 |
1970年 | 255篇 |
1969年 | 245篇 |
1968年 | 184篇 |
1967年 | 185篇 |
1966年 | 166篇 |
1965年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
A robust method for selection of variables with the greatest discriminatory power is presented in the paper. The method deals with the two groups of data problem. An application of the method to some respiratory disease data and comparisons with classical procedures are given, also. 相似文献
22.
W Tymiński E Czestochowska A Hellmann A Kreglewski 《Folia haematologica (Leipzig, Germany : 1928)》1980,107(2):269-272
Coagulation and fibrinolysis were measured in the portal and peripheral circulation in 15 rabbits after ligation of the superior mesenteric artery. It was found that the local coagulation syndrome in the mesenteric region can be recognized by tests in blood samples taken from the peripheral circulation area. 相似文献
23.
In chronic renal failure AMP-deaminase operates in the erythrocytes at a much higher velocity than in healthy subjects, with a simultaneous shift from the AMP-adenine-inosine-hypoxanthine pathway (55% and 19%, respectively) to the pathway initiated by AMP-deaminase (45% and 81%, respectively). 相似文献
24.
25.
26.
27.
The development of tolerance to ethanol-induced hypothermia and hypnosis, and cross-tolerance with morphine was studied in mice and rats. Ethanol significantly decreased the body temperature in rats (3.0 and 3.2 g/kg) and in mice (3.5 and 4.0 g/kg). Chronic administration of ethanol resulted in the tolerance not only to ethanol hypothermia but also to hypothermic effects of morphine in examined animals. Implantation of morphine pellets caused the development of cross tolerance to ethanol-induced hypothermia in rats but not in mice. The hypnotic effect of ethanol was significantly shorter in chronic alcoholized rats but not in morphine-implanted rats. Neither chronic ethanol administration nor implantation of morphine pellets changed the duration of ethanol-induced hypnosis in mice. These results seem to support the hypothesis on the opiate-like mechanism of ethanol action. 相似文献
28.
29.
The fluorometric method is described for determination of the final product of dopamine metabolism homovanillic acid in urine, amniotic fluid and tissue extracts. The metabolite was isolated using three chromatographic columns (1-Amberlit CG-50, 2-Dowex AG 1 x 2, 8-Aluminium oxide). Oxidation of eluates to emitter was done with potassium ferricyanide in alkalic medium. The use of internal standards made high recovery of compound and a good specificity and sensitivity of detection. 相似文献
30.