全文获取类型
收费全文 | 47393篇 |
免费 | 4038篇 |
国内免费 | 102篇 |
专业分类
耳鼻咽喉 | 461篇 |
儿科学 | 1257篇 |
妇产科学 | 1127篇 |
基础医学 | 6621篇 |
口腔科学 | 1363篇 |
临床医学 | 5473篇 |
内科学 | 9701篇 |
皮肤病学 | 748篇 |
神经病学 | 4704篇 |
特种医学 | 1475篇 |
外科学 | 5576篇 |
综合类 | 913篇 |
一般理论 | 29篇 |
预防医学 | 4761篇 |
眼科学 | 846篇 |
药学 | 3918篇 |
2篇 | |
中国医学 | 134篇 |
肿瘤学 | 2424篇 |
出版年
2023年 | 328篇 |
2022年 | 497篇 |
2021年 | 1051篇 |
2020年 | 577篇 |
2019年 | 989篇 |
2018年 | 1250篇 |
2017年 | 925篇 |
2016年 | 980篇 |
2015年 | 1171篇 |
2014年 | 1436篇 |
2013年 | 2049篇 |
2012年 | 2947篇 |
2011年 | 2989篇 |
2010年 | 1606篇 |
2009年 | 1349篇 |
2008年 | 2359篇 |
2007年 | 2531篇 |
2006年 | 2385篇 |
2005年 | 2354篇 |
2004年 | 2163篇 |
2003年 | 2106篇 |
2002年 | 1921篇 |
2001年 | 930篇 |
2000年 | 949篇 |
1999年 | 829篇 |
1998年 | 426篇 |
1997年 | 348篇 |
1996年 | 330篇 |
1995年 | 337篇 |
1994年 | 304篇 |
1993年 | 272篇 |
1992年 | 656篇 |
1991年 | 592篇 |
1990年 | 574篇 |
1989年 | 560篇 |
1988年 | 495篇 |
1987年 | 516篇 |
1986年 | 481篇 |
1985年 | 528篇 |
1984年 | 478篇 |
1983年 | 363篇 |
1982年 | 369篇 |
1981年 | 309篇 |
1980年 | 301篇 |
1979年 | 400篇 |
1978年 | 330篇 |
1976年 | 277篇 |
1974年 | 313篇 |
1973年 | 305篇 |
1972年 | 262篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
J. Wayne Streilein Scott Cousins Jo S. P. Williamson 《International ophthalmology》1990,14(5-6):317-325
Regulation of T cell-dependent immune responses is mediated in part by bone marrow-derived antigen presenting cells (APC) that (a) process and present antigens which engage the T cell receptor and (b) secrete cytokines that influence the threshold of T cell activation. The anterior chamber of the eye is lined by the corneal endothelium (which rests on a stroma and epithelium that is devoid of class II MHC + APC) and iris/ciliary body (which contain significant numbers of bone marrow-derived cells, one third of which are class II MHC +). When tested in vitro, these potential APCs fail to present antigens in a form that activates T cells. Moreover, iris/ciliary body cells actually suppress activation of T cells exposed to antigens on conventional APC. In addition, aqueous humor under normal circumstances contains factors (one of which is TGFB) that are potent inhibitors of antigen-driven T cell activation, but spare other aspects of T cell function. Evidence suggests that the bone marrow-derived cells in iris/ciliary body are the source of this factor. Thus, the anterior chamber contains powerful forces that can prevent induction and can suppress expression of T cell mediated immunity. It is proposed that these forces are responsible for immunologic privilege and anterior chamber associated immune deviation, and for suppressing pathologic proliferation and inflammation in the anterior segment of the eye. 相似文献
62.
S. Aziz L. A. Soine S. L. Lewis A. P. Kruse W. C. Levy K. M. Wehe D. P. Fishbien M. D. Allen 《Transplant international》1997,10(6):446-450
A review of factors contributing to early mortality after cardiac transplantation revealed that up to 25 % of deaths were
due to primary graft dysfunction unrelated to rejection or infection. In light of this finding, evaluation of a donor heart
with regard to its suitability for transplantation takes on added importance. In an effort to screen the suitability of donor
hearts in the region covered by the Northwest Organ Procurement Agency (USA), all donors are evaluated by two-dimensional
transthoracic echocardiography as part of the initial evaluation. A total of 110 donor echocardiograms were reviewed and an
attempt was made to correlate the 30-day outcome with the parameters measured. An unexpected finding was that the presence
of left ventricular hypertrophy in the donor heart was associated with an increase in the incidence of donor heart dysfunction
compared with donors with normal echocardiographic profiles (33 % vs 3 %, P = 0.007).
Received: 12 February 1996 Received after resision: 27 June 1997 Accepted: 14 July 1997 相似文献
63.
64.
Jung Han Kim Sang Jun Lee Young Bok Han Jung Jo Moon Jong Bae Kim 《Archives of pharmacal research》1994,17(2):115-118
This paper describes the isolation of isoguanosine from Croton tiglium L. and its cytotoxic effect against several tumor cell lines in culture and newly reports that isoguanosine has an antitumor activity against implanted S-180 ascitic tumor mice. Isoguanosine is effective at the dose of 24 mg/kg/day x 5, with T/C value of 168%. Isoguanosine inhibits the growth of S-180 and Ehrlich solid tumor in mice at the optimal doses of 96 mg/kg/day x 12 and 48 mg/kg/day x 12, with 1-T/C values of 65% and 60%, respectively. 相似文献
65.
Inhibition of cap (m7GpppXm)-dependent endonuclease of influenza virus by 4-substituted 2,4-dioxobutanoic acid compounds. 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Antimicrobial agents and chemotherapy》网站下载免费的PDF全文](/ch/ext_images/free.gif)
66.
J. L. Lewis C. E. Rhoades D. E. Bice J. R. Harkema J. A. Hotchkiss D. M. Sylvester A. R. Dahl 《Anatomical record (Hoboken, N.J. : 2007)》1992,232(4):620-627
The observation of high levels of xenobiotic metabolizing enzyme activity in the olfactory mucosa has produced speculation on the functional significance of these enzymes in the nose. Hypothesized roles include protection of the nasal epithelium, lung, and other downstream tissues, and termination or modification of olfactory responses. The enzyme rhodanese metabolizes cyanide, which is a commonly inhaled toxicant and an odorant and therefore of interest to both toxicologists and olfactory neurobiologists. The cellular localization of this enzyme within the olfactory mucosa will have important consequences for its ability to protect specific cells, as well as its ability to alter the concentration of inhaled cyanide at receptors, and therefore could provide clues as to its function in this tissue. We have compared the distribution of this enzyme in two species, the rat and the cow, using immunohistochemical localization techniques employing species-specific polyclonal antisera raised in our laboratory. In the rat, rhodanese-like immunoreactivity was greatest within the apical portion of the sustentacular cells, the basal cells, and the duct cells of Bowman's glands. Very little to no reaction was observed in the acinar cells of Bowman's glands. In the cow, however, the acinar cells and duct cells of Bowman's glands showed intense immunoreactivity with little to no reaction observed in the sustentacular or basal cells. The differences in localization of rhodanese in these two species may have important implications for cell types at risk during inhalation of cyanide or organonitrile compounds metabolized to cyanide within the nasal mucosa. In addition, the difference in distribution in the two species emphasizes the importance of considering enzyme activity and localization in the determination of an appropriate animal model for study of both nasal toxicology and olfactory responsiveness in humans. 相似文献
67.
Review article: the use of biotherapeutic agents in the prevention and treatment of gastrointestinal disease 总被引:1,自引:1,他引:0
There is presently a lack of well conducted clinical trials demonstrating any significant benefits of probiotics in humans. With the exception of diarrhoea due to rotavirus infection in children there is little evidence from randomized, double-blind, placebo-controlled studies that bacterial probiotics have a significant beneficial action in preventing diarrhoea of any cause. The yeast Saccharomyces boulardii has been shown to be of benefit in the prevention of antibiotic-associated diarrhoea but not in preventing infection with Clostridium difficile . S. boulardii may also be of benefit in preventing relapse of C. difficile infection. Because of the simplicity of in vitro systems and some animal models, beneficial characteristics of probiotics such as the ability of bacteria to bind to epithelial surfaces are not always transferable to humans. Thus any postulated benefit from consumption of probiotic bacteria should only be accepted as fact after testing in clinical studies.
This review outlines our present knowledge of the mode of action of probiotics and presents the data from clinical trials on their use. 相似文献
This review outlines our present knowledge of the mode of action of probiotics and presents the data from clinical trials on their use. 相似文献
68.
69.
Denise M Connor Shawn Binkley Neil O Fishman Leanne B Gasink Darren Linkin Ebbing Lautenbach 《Infection control and hospital epidemiology》2007,28(12):1408-1410
We examined the possible unintended consequences of a 72-hour automatic order to discontinue vancomycin therapy in an antimicrobial stewardship program (ASP). Of 120 patients, 11 had vancomycin therapy discontinued at 72 hours without a call to the ASP, and 7 experienced a treatment interruption of 6-36 hours. All discontinuation of therapy was considered appropriate, and the 7 treatment interruptions did not have clear clinical consequences. Only one-third of patients had ASP stickers that warned of impending discontinuation of vancomycin therapy placed appropriately in the medical record. 相似文献