全文获取类型
收费全文 | 347596篇 |
免费 | 40723篇 |
国内免费 | 141篇 |
专业分类
388460篇 |
出版年
2018年 | 3088篇 |
2016年 | 4299篇 |
2015年 | 5908篇 |
2014年 | 6953篇 |
2013年 | 9808篇 |
2012年 | 11069篇 |
2011年 | 11123篇 |
2010年 | 7462篇 |
2009年 | 6707篇 |
2008年 | 9724篇 |
2007年 | 10113篇 |
2006年 | 9464篇 |
2005年 | 9152篇 |
2004年 | 9184篇 |
2003年 | 8932篇 |
2002年 | 8772篇 |
2001年 | 15038篇 |
2000年 | 15059篇 |
1999年 | 12125篇 |
1998年 | 4435篇 |
1997年 | 4495篇 |
1996年 | 4278篇 |
1995年 | 4110篇 |
1994年 | 4106篇 |
1993年 | 3997篇 |
1992年 | 10395篇 |
1991年 | 9917篇 |
1990年 | 9729篇 |
1989年 | 9492篇 |
1988年 | 8826篇 |
1987年 | 8504篇 |
1986年 | 7629篇 |
1985年 | 7795篇 |
1984年 | 6460篇 |
1983年 | 5629篇 |
1982年 | 4529篇 |
1981年 | 4016篇 |
1980年 | 3802篇 |
1979年 | 6461篇 |
1978年 | 4877篇 |
1977年 | 4553篇 |
1976年 | 4225篇 |
1975年 | 4567篇 |
1974年 | 4981篇 |
1973年 | 5027篇 |
1972年 | 4625篇 |
1971年 | 4302篇 |
1970年 | 3643篇 |
1969年 | 3549篇 |
1968年 | 3166篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
T Smith 《BMJ (Clinical research ed.)》1980,281(6252):1410-1411
93.
94.
Selective diapedesis of Th1 cells induced by endothelial cell RANTES. 总被引:16,自引:0,他引:16
T Kawai M Seki K Hiromatsu J W Eastcott G F Watts M Sugai D J Smith S A Porcelli M A Taubman 《Journal of immunology (Baltimore, Md. : 1950)》1999,163(6):3269-3278
Differentiated CD4 T cells can be divided into Th1 and Th2 types based on the cytokines they produce. Differential expression of chemokine receptors on either the Th1-type or the Th2-type cell suggests that Th1-type and Th2-type cells differ not only in cytokine production but also in their migratory capacity. Stimulation of endothelial cells with IFN-gamma selectively enhanced transmigration of Th1-type cells, but not Th2-type cells, in a transendothelial migration assay. Enhanced transmigration of Th1-type cells was dependent on the chemokine RANTES produced by endothelial cells, as indicated by the findings that Ab neutralizing RANTES, or Ab to its receptor CCR5, inhibited transmigration. Neutralizing Ab to chemokines macrophage-inflammatory protein-1alpha or monocyte chemotactic protein-1 did not inhibit Th1 selective migration. Whereas anti-CD18 and anti-CD54 blocked basal levels of Th1-type cell adherence to endothelial cells and also inhibited transmigration, anti-RANTES blocked only transmigration, indicating that RANTES appeared to induce transmigration of adherent T cells. RANTES seemed to promote diapedesis of adherent Th1-type cells by augmenting pseudopod formation in conjunction with actin rearrangement by a pathway that was sensitive to the phosphoinositol 3-kinase inhibitor wortmannin and to the Rho GTP-binding protein inhibitor, epidermal cell differentiation inhibitor. Thus, enhancement of Th1-type selective migration appeared to be responsible for the diapedesis induced by interaction between CCR5 on Th1-type cells and RANTES produced by endothelial cells. Further evidence that CCR5 and RANTES play a modulatory role in Th1-type selective migration derives from the abrogation of this migration by anti-RANTES and anti-CCR5 Abs. 相似文献
95.
The fine structure of meiotic chromosome pairing in natural and artificial Lilium polyploids 总被引:1,自引:0,他引:1
P B Moens 《Journal of cell science》1970,7(1):55-63
96.
97.
Six hundred foramina transversaria (FT) of the axis vertebrae of 4 population groups were examined for the presence of erosion of the lateral articular mass. Of these, 127 (21%) and 72 (12%) presented with moderate and marked erosion, respectively. Evidence is presented incriminating the tortuosity of the vertebral artery as well as congenital factors in the etiology of the erosion of the FT. Attention is drawn to the possible correlation between angulation of the transverse process of the axis and erosion of the FT. 相似文献
98.
Two internal herinias of the intestines were found in adult males. One was a large translucent avascular membranous sac contining the small intestine from the duodenojejunal flexure to a point 6 in. proximal to the ileocaecal junction. The other was a peritoneal sac enclosing the small intestine, appendix, caecum and 6 in. of the ascending colon. The mesenteric and colic vessels were normal. Both hernias conformed to PAPEZ's concept of the so-called paraduodenal hernia that the hernial sac is derived from the umbilical coelom. The authors suggest that most of the so-called paraduodenal hernias are derived from the embryonic umbilical peritoneal diverticulum rather than from the peritoneal recesses or mesentery of the colon. 相似文献
99.
100.
The liver and kidney of rat underwent severe histopathological lesions when treated with a single bolus dose of carbendazim, a fungicide, particularly affecting the hepatocytes and the renal corpuscles, respectively. The effects appear to be manifestations of the microtubule-disrupting activity of carbendazim. Treatment of carbendazim-treated rats with the powder of tuberous root of Withania somnifera (Ashwagandha) for 48 days resulted in complete cure of these organs. The results indicate that Withania somnifera would be an effective curative for carbendazim-induced histopathological changes in the liver and kidney. 相似文献