全文获取类型
收费全文 | 601293篇 |
免费 | 58298篇 |
国内免费 | 404篇 |
出版年
2018年 | 5540篇 |
2016年 | 7009篇 |
2015年 | 8300篇 |
2014年 | 10364篇 |
2013年 | 14874篇 |
2012年 | 16932篇 |
2011年 | 17549篇 |
2010年 | 12065篇 |
2009年 | 10889篇 |
2008年 | 15628篇 |
2007年 | 16397篇 |
2006年 | 15618篇 |
2005年 | 14974篇 |
2004年 | 15032篇 |
2003年 | 14364篇 |
2002年 | 14313篇 |
2001年 | 26302篇 |
2000年 | 26561篇 |
1999年 | 20928篇 |
1998年 | 6772篇 |
1997年 | 6880篇 |
1996年 | 6388篇 |
1995年 | 6058篇 |
1994年 | 5972篇 |
1993年 | 5882篇 |
1992年 | 16929篇 |
1991年 | 16811篇 |
1990年 | 16482篇 |
1989年 | 16094篇 |
1988年 | 15153篇 |
1987年 | 14311篇 |
1986年 | 13411篇 |
1985年 | 13731篇 |
1984年 | 11207篇 |
1983年 | 9526篇 |
1982年 | 7140篇 |
1981年 | 6519篇 |
1980年 | 6108篇 |
1979年 | 10721篇 |
1978年 | 8526篇 |
1977年 | 7858篇 |
1976年 | 7483篇 |
1975年 | 8598篇 |
1974年 | 9532篇 |
1973年 | 9438篇 |
1972年 | 8633篇 |
1971年 | 7921篇 |
1970年 | 6845篇 |
1969年 | 6747篇 |
1968年 | 6205篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
T. B. Lapirova V. R. Mikryakova A. S. Mavrin G. A. Yinogradova 《Journal of Evolutionary Biochemistry and Physiology》2000,36(1):47-51
The paper presents data on a change in lysozyme content in tissues of spleen, liver and heart in fry of the Lena River sturgeon
exposed to the presence of sublethal concentrations of Hg2+, Cd2+, and Cu2+ under conditions of chronic experiment. It has been shown that the lysozyme content in fish tissues varies and has a phasic
character. The amplitude of fluctuations of this parameter depends on the moment of sampling, nature of the toxicant, and
structural-functional organization of the studied organs. 相似文献
56.
Staphylococcal gamma-hemolysin and leukocidin are bi-component cytolysins, consisting of LukF (or Hlg1)/Hlg2 and LukF/LukS, respectively. Here, we purified serum inhibitors of gamma-hemolysin and leukocidin from human plasma. Protein sequencing showed that the purified inhibitors of 62, 57, 50 and 38 kDa were the vitronectin fragments with truncation(s) of the C-terminal or both N- and C-terminal regions. The purified vitronectin fragments specifically bound to the Hlg2 component of gamma-hemolysin and the LukS component of leukocidin to form high-molecular-weight complexes with them, leading to inhibition of the toxin-induced lysis of human erythrocytes and human polymorphonuclear leukocytes, respectively. Intact vitronectin also showed inhibitory activity to the toxins. The ability of gamma-hemolysin and leukocidin to bind vitronectin and its fragments is a novel function of the pore-forming cytolysins. 相似文献
57.
Although phorbol 12-myristate 13-acetate (PMA) inhibits apoptosis and promotes the growth of some types of cells, it induces apoptosis in other cells. We evaluated the apoptotic effects of PMA on murine fibroblasts (L-929) that had been exposed to ultraviolet-B (UV-B) radiation at 312 nm, which promotes tumor cell growth. Exposure to PMA alone did not induce Fas, Fas-L, or apoptosis. Cells exposed to mild UV-B irradiation (80 J/m(2)) alone exhibited a slight expression of Fas and Fas-L 36 to 48 h after the exposure, and exhibited apoptosis as evidenced by DNA fragmentation 72 h after exposure. The addition of PMA (0.8 x 10(-5) to 3.2 x 10(-5) M) to the medium 24 h after the UV-B exposure markedly and dose-dependently enhanced these cell responses. Confluent untreated cells, cells cocultured with PMA, and cells cocultured with PMA for 24 h after the UV-B exposure consistently expressed mRNAs for wild-type p53, bcl-2, and ICE. Expression of c-myc mRNA was initially observed, but became undetectable in the cells cocultured for 24 h with a high concentration of PMA (3.2 x 10(-5) M) following UV-B exposure. Such cells subsequently exhibited the maximal apoptotic response. We conclude that mild exposure to UV-B altered murine fibroblast cells in such a way as to facilitate their death by apoptosis upon addition of PMA. 相似文献
58.
A finite element based method to determine the incremental elastic material properties of planar membranes was developed and evaluated. The method is applicable to tissues that exhibit inhomogeneity, geometric and material nonlinearity, and anisotropy. Markers are placed on the tissue to form a four-node quadrilateral element. The specimen is loaded to an initial reference state, then three incremental loading sets are applied and the nodal displacements recorded. One of these loadings must include shear. These data are used to solve an over-determined system of equations for the tangent stiffness matrix. The method was first verified using analytical data. Next, data obtained from a latex rubber sheet were used to evaluate experimental procedures. Finally, experiments conducted on preconditioned rat skin revealed nonlinear orthotropic behavior. The vector norm comparing the applied and calculated nodal force vectors was used to evaluate the accuracy of the solutions. 相似文献
59.
60.
Trigger finger is a relatively common clinical entity, most frequently caused by stenosing tenosynovitis. Several other conditions not related to tenosynovitis also have been described as a cause of triggering, and these have been reviewed. We present a rare anomaly of the fourth lumbrical muscle insertion as a cause of triggering of the right little finger. This was completely relieved following excision of the anomalous muscle. This rare anatomic variant should be added to the list of potential causes of trigger finger. 相似文献