首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   428478篇
  免费   44461篇
  国内免费   212篇
  2016年   4776篇
  2015年   6418篇
  2014年   7517篇
  2013年   11188篇
  2012年   12181篇
  2011年   12593篇
  2010年   8556篇
  2009年   7867篇
  2008年   11239篇
  2007年   11835篇
  2006年   11107篇
  2005年   10548篇
  2004年   10615篇
  2003年   10353篇
  2002年   10113篇
  2001年   17516篇
  2000年   17532篇
  1999年   14165篇
  1998年   5052篇
  1997年   5350篇
  1996年   5059篇
  1995年   4797篇
  1994年   4669篇
  1993年   4678篇
  1992年   12341篇
  1991年   12134篇
  1990年   12151篇
  1989年   11926篇
  1988年   11236篇
  1987年   10566篇
  1986年   9877篇
  1985年   10299篇
  1984年   8487篇
  1983年   7313篇
  1982年   5644篇
  1981年   5038篇
  1980年   4723篇
  1979年   8123篇
  1978年   6341篇
  1977年   5966篇
  1976年   5709篇
  1975年   6159篇
  1974年   6727篇
  1973年   6592篇
  1972年   6146篇
  1971年   5546篇
  1970年   4778篇
  1969年   4794篇
  1968年   4456篇
  1967年   3818篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
The authors studies the effects of blood serum and IgG fraction from dogs immunized with brain and blood sera from patients with multiple sclerosis and schizophrenia on lipid peroxidation in rat brain homogenates. Measured the content of diene conjugates (DC) and malonic dialdehyde (MDA) in the rat brain after administering the IgG fraction. It was established that antioxidant activity of blood sera and IgG fraction from control animals and donors was significantly higher as compared to experimental. Administration of the IgG fraction brought about an increase in the content of DC and MDA in the brain of experimental animals. It is concluded that complement-dependent brain antibodies present in the blood serum of patients with schizophrenia and multiple sclerosis potentiate lipid peroxidation in the cerebral tissue and that the unsophisticated and informative method for antibody determination may be used in clinical practice.  相似文献   
202.
203.
204.
205.
206.
207.
208.
We isolated and sequenced 26 microsatellites from two genomic libraries of peach cultivar 'Redhaven', enriched for AC/GT and AG/CT repeats, respectively. For 17 of these microsatellites, it was possible to demonstrate Mendelian inheritance. Microsatellite polymorphism was assayed in 50 peach and nectarine cultivars. Of the 1300 PCRs carried out, all but two produced amplified products of the expected size. All microsatellites were polymorphic, showing 2-8 alleles per locus. Heterozygosity ranged from 0.04-0.74 (mean 0.47); the discrimination power (PD) ranged from 0.04-0.84 (mean 0.60). Cultivar heterozygosity varied greatly, with one cultivar ('Independence') being homozygous at all loci. The set of microsatellites discriminated all cultivars investigated, except several sport mutations, i.e., 'Dixitime' vs. 'Springcrest', 'Compact Redhaven' vs. 'Redhaven', and two pairs of cultivars, 'Venus' vs. 'Orion' and 'Elegant Lady' vs. 'Rome Star', whose pedigrees are controversial. We were able to analyze the paternity of several cultivars. In most cases, the parenthood was confirmed. The comparison of three long-living 'Redhaven' accessions supplied by different repositories did not provide any evidence of somatic instability of microsatellites. Hence, microsatellites, ranked according to their information content, are recommended as markers of choice for peach fingerprinting and suggestions are provided for interpreting band profiles and the correct sizing of alleles.  相似文献   
209.
Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy.  相似文献   
210.
The infection of Planorbarius banaticus with sporocysts of Cotylurus cornutus is accompanied by an increase in aldolase activity of molluscs' haemolymph of 1.2 fold. In solutions of nitroammofoska (0.1, 1 and 10 mg/1) the activity of this ferment in infected individuals increases much higher than in non-infected ones. This results in fast carbohydrate expenditures by molluscs, intermediate hosts of trematodes, and their death from exhaustion.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号