全文获取类型
收费全文 | 1102667篇 |
免费 | 113613篇 |
国内免费 | 519篇 |
出版年
2018年 | 10669篇 |
2017年 | 10173篇 |
2016年 | 14114篇 |
2015年 | 17950篇 |
2014年 | 21320篇 |
2013年 | 31524篇 |
2012年 | 35631篇 |
2011年 | 36876篇 |
2010年 | 24729篇 |
2009年 | 22551篇 |
2008年 | 32811篇 |
2007年 | 34294篇 |
2006年 | 32099篇 |
2005年 | 30612篇 |
2004年 | 30436篇 |
2003年 | 29399篇 |
2002年 | 28622篇 |
2001年 | 45129篇 |
2000年 | 44839篇 |
1999年 | 36003篇 |
1998年 | 13718篇 |
1997年 | 13855篇 |
1996年 | 13258篇 |
1995年 | 12327篇 |
1994年 | 11965篇 |
1993年 | 12003篇 |
1992年 | 29984篇 |
1991年 | 29442篇 |
1990年 | 28803篇 |
1989年 | 28303篇 |
1988年 | 26335篇 |
1987年 | 25111篇 |
1986年 | 23468篇 |
1985年 | 23812篇 |
1984年 | 19799篇 |
1983年 | 17227篇 |
1982年 | 13348篇 |
1981年 | 12028篇 |
1980年 | 11244篇 |
1979年 | 18751篇 |
1978年 | 14811篇 |
1977年 | 13567篇 |
1976年 | 12959篇 |
1975年 | 14332篇 |
1974年 | 15440篇 |
1973年 | 15184篇 |
1972年 | 13955篇 |
1971年 | 12600篇 |
1970年 | 10986篇 |
1969年 | 10826篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
The effect of a 30-day treatment with Madiol was studied on the activity of some enzymes, nucleic acids, protein and glycogen content of the liver of adult female rats and youngs born from mothers treated during pregnancy. Madiol caused a significant increase in SDH and Atp-ase activity, and decreased glycogen and acid phosphatase. 相似文献
972.
L L Kiseleva G N Novodarova M E Vol'pin A D Vinogradov 《Biokhimii?a (Moscow, Russia)》1982,47(11):1877-1882
The effects of the decamethyloctadehydrocorrine-cobalt complex (Co-C) on respiration and the ATP-synthetase activity of rat liver mitochondria were investigated. The Co-C complex was found to be an effective shunt of the respiratory chain. It accepts electrons from ubiquinone and donates them directly to O2. The Co-C complex inhibits the ATPase and ATP-synthetase activities of mitochondria. 相似文献
973.
974.
A new micronucleus test using peripheral blood erythrocytes of the newt Pleurodeles waltl to detect mutagens in fresh-water pollution 总被引:4,自引:0,他引:4
A model micronucleus test system using peripheral blood erythrocytes from larvae of Pleurodeles waltl is described. The most suitable larval stage for testing chemical treatments was determined. Larvae were reared in water containing one of the 4 compounds: benzo[a]pyrene (BaP), ethyl methanesulphonate (EMS), diethyl sulphate (DES) and N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Response curves as a function of treatment duration over a period of 16 days were plotted for 3 different concentrations of the 4 compounds in order to optimize conditions for a low dose micronucleus test. This model can be used as a monitoring system for the detection of fresh water pollution and can also be employed for clastogen screening of chemical compounds. The test is sensitive, reliable and easy to use. 相似文献
975.
976.
Large deformation mechanics of the enucleated eyeball 总被引:1,自引:0,他引:1
L A Taber 《Journal of biomechanical engineering》1984,106(3):229-234
Large deformation of enucleated pig eyeballs under rigid cylindrical indenters was studied analytically and experimentally. The analytic model for the eyeball consists of a fluid-filled spherical membrane composed of an incompressible, elastic material with an exponential strain energy function. The Rayleigh-Ritz technique provided an approximate solution via a potential energy formulation. Comparison with results from tests on eyeballs and a water-filled rubber (Mooney-Rivlin) shell shows good agreement at large deflection, where membrane action dominates. Due to the highly nonlinear stress-strain relations for the sclera, the load remains relatively small until the indenter displacement approaches 40-60 percent of the eyeball radius, and then the load increases rapidly. Depending on the indenter size, either a perforation or a rupture type of failure occurs. 相似文献
977.
978.
The self determinants recognized by human virus-immune T cells can be distinguished from the serologically defined HLA antigens 总被引:10,自引:0,他引:10
W E Biddison F E Ward G M Shearer S Shaw 《Journal of immunology (Baltimore, Md. : 1950)》1980,124(2):548-552
The self specificity of human influenza virus-immune cytotoxic T cells has been analyzed in order to clarify the relationship between the self antigens that they recognize and the serologically defined HLA-A and -B antigens. Virus-immune effectors from HLA-A2-positive donors were tested on panels of virus-infected target cells from donors who were either HLA-mismatched or matched only for HLA-A2. Virus-immune T cells from 11 out of 11 A2-positive donors lysed all A2-matched virus-infected target cells (and no HLA-mismatched targets), except that each of these effector cells consistently failed to lyse virus-infected target cells from one A2-positive donor (designated M7). Although the A2 specificity of donor M7 could also be distinguished from the A2 antigen of other donors by alloimmune cytotoxic T cells, no differences in the A2 antigen of donor M7 could be defined by extensive serologic analyses. These results indicate that there is a strong but incomplete association between a self antigen recognized by virus-immune T cells and the serologically defined HLA-A2 specificity. 相似文献
979.
980.
C Toga-Piquet A S Henderson J M Grillo A M Vagner-Capodano A Stahl 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1984,298(14):383-386
The Pig chromosomes that contain rDNA sites displayed a polymorphism in the distribution of the genes among the nucleolar organizers located on pairs Nos. 8 and 10. Two, or more often three, active sites were observed in the chromosomes of lymphocytes stimulated with phytohemagglutinin. Only 5% of the metaphases showed a 4th small active site. At the onset of stimulation most cells contained one-two nucleoli; four nucleoli were never observed. After prolonged stimulation, the number of nuclei containing three nucleoli increased. A 4th small nucleolus appeared in a few cells, presumably formed by activation of the smallest rDNA site. 相似文献