全文获取类型
收费全文 | 765篇 |
免费 | 65篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 48篇 |
妇产科学 | 6篇 |
基础医学 | 63篇 |
口腔科学 | 27篇 |
临床医学 | 76篇 |
内科学 | 128篇 |
皮肤病学 | 19篇 |
神经病学 | 252篇 |
特种医学 | 92篇 |
外科学 | 40篇 |
综合类 | 18篇 |
预防医学 | 10篇 |
眼科学 | 3篇 |
药学 | 31篇 |
肿瘤学 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 25篇 |
2011年 | 33篇 |
2010年 | 45篇 |
2009年 | 42篇 |
2008年 | 32篇 |
2007年 | 30篇 |
2006年 | 36篇 |
2005年 | 31篇 |
2004年 | 28篇 |
2003年 | 27篇 |
2002年 | 15篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 26篇 |
1998年 | 30篇 |
1997年 | 36篇 |
1996年 | 37篇 |
1995年 | 34篇 |
1994年 | 18篇 |
1993年 | 18篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1954年 | 1篇 |
排序方式: 共有835条查询结果,搜索用时 0 毫秒
81.
Nuclear RNA sequences coding for alpha and beta globins in erythroid cells: evidence for multiple intermediate molecules 总被引:1,自引:0,他引:1
The poly (A)-containing nuclear RNA from dimethylsulfoxide-induced Friend leukemia cells was fractionated by acrylamide gel electrophoresis in denaturing conditions and analyzed for alpha and beta globin RNA sequences. The results indicate that nuclear RNA contains one species of large-size RNA (0.6 X 10(6) daltons), which is the putative precursor for beta globin mRNA only. In addition, it was shown by electrophoretic analysis that the complex of RNA molecules not resolved by sucrose gradient centrifugation (11S) comprises sequences of decreasing size (0.34, 0.28, and 0.26 X 10(6) daltons), which might be the precursors of alpha and beta globin mRNA. 相似文献
82.
83.
84.
85.
Histopathology of the thymus of patients with acute lymphoblastic leukemia and lymphoblastic lymphoma in complete clinical remission 总被引:1,自引:0,他引:1
Rappaport H; Machover D; Bearman R; Nathwani B; Lemaigre MG; Santelli G; Verley JM; Canon C; Mathe G 《Blood》1981,58(4):852-855
The histologic features of thymuses from three patients who underwent thymectomy for acute lymphoblastic leukemia or lymphoblastic lymphoma in complete clinical remission are described. The thymuses from all three patients were fibrotic with a variability in the appearance of the lobules. Some of the lobules consisted predominantly of epithelial cells with small numbers of mature appearing lymphocytes, while other lobules were expanded and composed predominantly of cells having morphological features of immature lymphoid cells consistent with residual or recurrent disease. 相似文献
86.
Groopman JE; Hartzband PI; Shulman L; Salahuddin SZ; Sarngadharan MG; McLane MF; Essex M; Gallo R 《Blood》1985,66(3):742-744
The human T-lymphotropic virus type III (HTLV-III) is the primary cause of the acquired immunodeficiency syndrome (AIDS) and related disorders (ARC). Prior studies have reported that nearly all symptomatic patients with AIDS or ARC manifest antibody to HTLV-III. This observation has engendered efforts to screen for HTLV-III, especially prior to blood donation, with assays for antibody to HTLV-III. We report the first two cases, one with AIDS and one with ARC, that are HTLV-III virus positive but antibody negative. Accurate diagnosis of HTLV-III infection in some cases may require direct virus culture or tests for antigen. In addition, lack of HTLV-III antibody may indicate an atypical clinical course of AIDS. 相似文献
87.
Chetty R;University Health Network Princess Margaret Hospital University Avenue Fourth Floor Suite Toronto ON MG M Canada. runjan.chetty@uhn.on.ca 《Journal of clinical gastroenterology》2003,37(1):23-27
GOALS: The purpose of this review is to look at the evidence presented in the literature on the immunoexpression of p27 in cancers of the gastrointestinal tract and liver. BACKGROUND: Cell cycle proteins have been shown to play an important role in the oncogenesis of many tumors. Several of these proteins have been examined in concert and in isolation, and some have been put forward as putative tumor markers. p27, which is an important inhibitory protein in the cell cycle and belonging to a group of cyclin-dependent kinase inhibitors, has also been studied in several malignancies, most notably breast, lung, bladder, and prostate cancers. Considerable work has also been done on the expression of this protein in cancers occurring within the gastrointestinal tract. RESULTS: Cancers occurring in the major sites of the gastrointestinal tract (esophagus, stomach, and colorectum) and liver show a similar pattern with regard to p27 protein levels. p27 emerges as a statistically significant predictor of survival and tumor behavior. It has been suggested that p27 loss occurs early in the carcinogenesis process, with dysplastic epithelium having decreased expression. The more aggressive, metastasizing cancers tend to lack p27 expression as well. Some studies have also invoked the subcellular localization of p27 (cytoplasmic versus nuclear) as also being of prognostic value. CONCLUSION: Therefore, in gastrointestinal and hepatic cancers, low p27 expression is regarded as an important adverse prognostic factor. 相似文献
88.
89.
CD34 expression is regulated reciprocally with adhesion molecules in vascular endothelial cells in vitro 总被引:11,自引:1,他引:11
Delia D; Lampugnani MG; Resnati M; Dejana E; Aiello A; Fontanella E; Soligo D; Pierotti MA; Greaves MF 《Blood》1993,81(4):1001-1008
Freshly cultured vascular endothelial cells express the CD34 antigen in a diffuse cell surface pattern with some concentration on microvilli. Expression is downregulated with proliferation in continuous culture and undetectable after nine population doublings but can be maintained by restraining cell proliferation and promoting cell contact. Expression of CD34 at the antigen and mRNA levels on early passage cells is rapidly downregulated by interleukin-1 beta (IL-1 beta), interferon-gamma (INF-gamma), and tumor necrosis factor-alpha (TNF- alpha) under conditions in which these ligands upregulate the adhesion molecules: endothelial leukocyte adhesion molecule 1 (ELAM-1) and intracellular adhesion molecule 1 (ICAM-1). This reciprocal pattern of expression and the topographic distribution of CD34 molecules on the lumenal interdigitated microprocesses of adjacent endothelial cells in vivo suggest that CD34 might have a negative modulating role on adhesion functions of endothelia. 相似文献
90.