全文获取类型
收费全文 | 1037篇 |
免费 | 90篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 147篇 |
妇产科学 | 10篇 |
基础医学 | 116篇 |
口腔科学 | 20篇 |
临床医学 | 114篇 |
内科学 | 151篇 |
皮肤病学 | 7篇 |
神经病学 | 12篇 |
特种医学 | 164篇 |
外科学 | 260篇 |
综合类 | 12篇 |
预防医学 | 37篇 |
眼科学 | 5篇 |
药学 | 37篇 |
中国医学 | 2篇 |
肿瘤学 | 36篇 |
出版年
2021年 | 5篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 20篇 |
2014年 | 18篇 |
2013年 | 23篇 |
2012年 | 23篇 |
2011年 | 32篇 |
2010年 | 28篇 |
2009年 | 27篇 |
2008年 | 26篇 |
2007年 | 27篇 |
2006年 | 29篇 |
2005年 | 33篇 |
2004年 | 26篇 |
2003年 | 26篇 |
2002年 | 32篇 |
2001年 | 21篇 |
2000年 | 26篇 |
1999年 | 28篇 |
1998年 | 53篇 |
1997年 | 68篇 |
1996年 | 46篇 |
1995年 | 37篇 |
1994年 | 39篇 |
1993年 | 26篇 |
1992年 | 28篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 31篇 |
1988年 | 30篇 |
1987年 | 33篇 |
1986年 | 32篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1978年 | 10篇 |
1977年 | 16篇 |
1976年 | 8篇 |
1975年 | 10篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1971年 | 8篇 |
1969年 | 6篇 |
1967年 | 4篇 |
1966年 | 6篇 |
排序方式: 共有1135条查询结果,搜索用时 15 毫秒
41.
Complications from improperly placed biliary stents are not uncommon. Free loose wires from the ends of an uncovered stent can irritate and damage adjacent mucosal surfaces. Effective management can be achieved via percutaneous placement of a second stent to alter the orientation of the original stent. 相似文献
42.
43.
T. C. EL‐GALALY S. R. KRISTENSEN K. OVERVAD R. STEFFENSEN A. TJØNNELAND M. T. SEVERINSEN 《Journal of thrombosis and haemostasis》2012,10(10):2191-2193
See also Lowe GDO. Epidemiology of venous thromboembolism: the need for large (including prospective) studies and meta‐analyses. This issue, pp 2186–8 and Rosendaal FR. Etiology of venous thrombosis: the need for small original studies. This issue, pp 2189–90. 相似文献
44.
45.
46.
47.
48.
Interleukin-1-induced leukocyte extravasation across rat mesenteric microvessels is mediated by platelet-activating factor 总被引:6,自引:0,他引:6
Although our understanding of the molecular interactions that mediate the adhesion of leukocytes to venular endothelial cells has greatly expanded, very little is known about the mechanisms that mediate the passage of leukocytes across the vessel wall in vivo. The aim of the present study was to investigate the role of endogenously formed platelet-activating factor (PAF) in the process of leukocyte extravasation induced by interleukin-1 (IL-1). To determine at which stage of emigration PAF was involved, we studied the behavior of leukocytes within rat mesenteric microvessels by intravital microscopy. Rats were injected intraperitoneally with saline, recombinant rat IL-1 beta (IL-1 beta), or the peptide N-formyl-methionyl-leucyl- phenylalanine (FMLP) 4 hours before the exteriorization of the mesenteric tissue. In animals treated with IL-1 beta there was a significant increase in the number of rolling and adherent leukocytes within venules (20- to 40-micron diameter) and in the number of extravasated leukocytes in the tissue. Pretreatment of rats with the PAF receptor antagonist UK-74,505 had no effect on the leukocyte responses of rolling and adhesion, but significantly inhibited the migration of the leukocytes across the vessel wall induced by IL-1 beta (76% inhibition). A structurally unrelated PAF antagonist, WEB-2170, produced the same effect (64% inhibition). However, in contrast, UK- 74,505 had no effect on the leukocyte extravasation induced by FMLP, indicating selectivity for the response elicited by certain mediators. These results provide the first line of direct evidence for the involvement of endogenously formed PAF in the process of leukocyte extravasation induced by IL-1 in vivo. 相似文献
49.
CL Sanchez CS Biskup S Herpertz TJ Gaber CM Kuhn SH Hood FD Zepf 《The international journal of neuropsychopharmacology / official scientific journal of the Collegium Internationale Neuropsychopharmacologicum (CINP)》2015,18(10)
The neurotransmitters serotonin and dopamine both have a critical role in the underlying neurobiology of different behaviors. With focus on the interplay between dopamine and serotonin, it has been proposed that dopamine biases behavior towards habitual responding, and with serotonin offsetting this phenomenon and directing the balance toward more flexible, goal-directed responding. The present focus paper stands in close relationship to the publication by Worbe et al. (2015), which deals with the effects of acute tryptophan depletion, a neurodietary physiological method to decrease central nervous serotonin synthesis in humans for a short period of time, on the balance between hypothetical goal-directed and habitual systems. In that research, acute tryptophan depletion challenge administration and a following short-term reduction in central nervous serotonin synthesis were associated with a shift of behavioral performance towards habitual responding, providing further evidence that central nervous serotonin function modulates the balance between goal-directed and stimulus-response habitual systems of behavioral control. In the present focus paper, we discuss the findings by Worbe and colleagues in light of animal experiments as well as clinical implications and discuss potential future avenues for related research. 相似文献
50.
Crosslinking the CD27 antigen on T cells provides a costimulatory signal that, in concert with T-cell receptor crosslinking, can induce T- cell proliferation and cellular immune activation. We find that chronic lymphocytic leukemia (CLL) B cells from most patients coexpress both membrane-bound and soluble CD27, along with its newly identified ligand, CD70. The expression of soluble CD27 may preclude leukemic B cells from stimulating T cells via CD70, thereby potentially impairing their ability to function as effective antigen-presenting cells. We find that leukemic B-cell expression of soluble and membrane-bound CD27 can be downmodulated through a CD40-dependent signal. This signal also induces enhanced expression of CD70 on both normal and leukemic B cells. We find that tumor necrosis factor (TNF)-alpha, or the Th1 cytokine interferon (IFN)-gamma, also can induce downmodulation of CD27, whereas Th2-associated cytokines interleukin-4 (IL-4) or IL-10 can enhance leukemic B-cell expression of this accessory molecule. The modulation of CD27 induced by these conditions is accompanied by reciprocal changes in the expression levels of CD70, suggesting that these accessory molecules may be engaged in reciprocal receptor-ligand downmodulation. Consistent with this, we observe that co-culture of CLL B cells with transfected murine plasmacytoma cells that express human CD70 affects downmodulation of CD27 and enhanced expression of CD70 on leukemic B cells, but does not affect expression of CD27 mRNA. However, we find that CD40-crosslinking, in addition to reducing the level of CD27 protein, also reduces leukemic B-cell expression of CD27 mRNA. This argues that the changes in the expression levels of CD27 following CD40-signaling are not simply due to induced increases in the expression levels of CD70. Finally, we demonstrate that reciprocal changes in expression of CD27 and CD70 may contribute to the enhanced antigen-presenting capacity of CLL B cells after CD40-dependent leukemic B-cell activation. These findings expand the understanding of the regulation of costimulatory molecules important in antigen presentation and also have implications for the immunobiology of and therapy for CLL. 相似文献