首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   46843篇
  免费   3450篇
  国内免费   163篇
耳鼻咽喉   486篇
儿科学   1023篇
妇产科学   925篇
基础医学   5937篇
口腔科学   1159篇
临床医学   4948篇
内科学   10017篇
皮肤病学   523篇
神经病学   3882篇
特种医学   1529篇
外国民族医学   1篇
外科学   7785篇
综合类   692篇
一般理论   33篇
预防医学   3980篇
眼科学   1282篇
药学   3096篇
中国医学   43篇
肿瘤学   3115篇
  2022年   295篇
  2021年   834篇
  2020年   500篇
  2019年   742篇
  2018年   884篇
  2017年   618篇
  2016年   725篇
  2015年   875篇
  2014年   1265篇
  2013年   1922篇
  2012年   2770篇
  2011年   2922篇
  2010年   1634篇
  2009年   1528篇
  2008年   2633篇
  2007年   2677篇
  2006年   2692篇
  2005年   2906篇
  2004年   2789篇
  2003年   2562篇
  2002年   2418篇
  2001年   583篇
  2000年   499篇
  1999年   625篇
  1998年   637篇
  1997年   495篇
  1996年   442篇
  1995年   416篇
  1994年   362篇
  1993年   339篇
  1992年   444篇
  1991年   407篇
  1990年   374篇
  1989年   339篇
  1988年   332篇
  1987年   338篇
  1986年   350篇
  1985年   354篇
  1984年   396篇
  1983年   405篇
  1982年   459篇
  1981年   426篇
  1980年   378篇
  1979年   286篇
  1978年   323篇
  1977年   302篇
  1976年   293篇
  1975年   240篇
  1974年   239篇
  1973年   249篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
171.
172.
The concept of prosthesis-directed implant-supported restoration is well accepted. The implementation of this principle for patients requesting full fixed implant-supported maxillary prosthetics has not been thoroughly described. We present a technique for the evaluation and preprosthetic surgical management of patients who are edentulous in the maxilla and wish to have fixed implant-supported crown and bridge prosthetics.  相似文献   
173.
Case reports have suggested that amphetamine abuse causes excessive secretion of thyrotropin (TSH) and thyroxine (T4). Such an amphetamine-induced effect might be noradrenergic-mediated in the hypothalamus. The current controlled study examined oral d-amphetamine effects on the hypothalamic-pituitary-thyroid axis in normal humans. No acute effects were seen on TSH, T3 or T4 levels. d-Amphetamine elevated cortisol levels at 180 min, as previously reported.  相似文献   
174.
D G Burleson  A D Mason  Jr    B A Pruitt  Jr 《Annals of surgery》1988,207(2):208-212
Subpopulation analysis of peripheral blood lymphocytes is a frequently used measure of immunocompetence. Yet, little is known about the lymphocyte subpopulations in the circulation and lymphoid organs after severe trauma. Blood, spleen, and lymph node (LN) subpopulations were compared in a rat model of burn injury (B) and burn injury with infection (BI). B and BI rats received 30% total body surface scald burns. Infection was induced by seeding wounds with Pseudomonas aeruginosa. Subpopulations were identified by flow cytometry 48 hours after burn. Helper lymphocytes were selectively depleted from the circulation of BI but not B animals, which caused the ratio of helper to suppressor cells (HSR) in BI animals to decrease significantly compared with the unburned controls. Both LN helper and suppressor cells were decreased in BI animals and the HSR was unchanged, but a selective reduction in suppressor cells in B LN increased the HSR relative to unburned controls. Spleen subpopulations were unchanged for both B and BI groups. Subpopulation changes after trauma and infection were different for each tissue examined.  相似文献   
175.
M Mason 《Nursing times》1988,84(11):42-43
  相似文献   
176.
Recommendations for increased consumption of protein are among the most common approaches of popular or fad diets. This review summarizes the effects of dietary protein on satiety, energy intake, thermogenesis, and weight loss, as well as its effect on a variety of health outcomes in adults. In short-term studies, dietary protein modulates energy intake via the sensation of satiety and increases total energy expenditure by increasing the thermic effect of feeding. Whereas these effects did not contribute to weight and fat loss in those studies in which energy intake was fixed, one ad libitum study does suggest that a high-protein diet results in a greater decrease in energy intake, and therefore greater weight and fat loss. In terms of safety, there is little long-term information on the health effects of high-protein diets. From the available data, however, it is evident that the consumption of protein greater than two to three times the U.S. Recommended Daily Allowance contributes to urinary calcium loss and may, in the long term, predispose to bone loss. Caution with these diets is recommended in those individuals who may be predisposed to nephrolithiasis or kidney disease, and particularly in those with diabetes mellitus.  相似文献   
177.
178.
179.
180.
The exact opioid-sensitive receptors participating in EtOH-seeking behaviors remains unclear. Previous studies have reported higher densities of micro-opioid receptor binding in the nucleus accumbens (NACC) of P relative to NP rats; however, no differences were seen in delta-receptor binding. In contrast to the NACC, substantially lower levels of micro-receptor binding have been observed in the ventral tegmental area (VTA) of both P and NP rats, albeit no line differences have been observed. In the present study, opioid receptors in the NACC, VTA, and hippocampus were evaluated for their capacity to regulate both EtOH- and saccharin-motivated behaviors in the genetically selected alcohol-preferring (P) rat. To accomplish this, nalmefene, an opiate antagonist with preferential binding affinity for the micro-opioid receptor was unilaterally or bilaterally infused during concurrent availability of 1 h daily EtOH (10% v/v) and saccharin (0.025 or 0.050% w/v) solutions. Rats performed under a two-lever fixed ratio (FR) schedule in which four responses on one lever produced the EtOH solution, and four on a second lever produced the saccharin solution. The results demonstrated that when responding maintained by both EtOH and saccharin are matched at basal levels, unilateral (1-60 microg) or bilateral (0.5-10 microg) microinjections of nalmefene into the NACC produced selective dose-dependent reductions on responding maintained by EtOH. Unilateral (40, 60 microg) and bilateral (10 microg) VTA infusions were also observed to selectively reduced EtOH responding; however, greater nalmefene doses were required and the magnitude of suppression on EtOH responding was markedly less compared with the NACC. The greater sensitivity of nalmefene to suppress EtOH responding in the NACC is likely due to the greater number of opioid receptors in the NACC relative to the VTA. Only bilateral infusion of the 40 microg dose in the NACC and VTA suppressed responding maintained by both EtOH and saccharin. In contrast, intrahippocampal infusions dose dependently suppressed EtOH- and saccharin-maintained responding over a range of doses (1-20 microg). The present study provides evidence that nalmefene suppresses EtOH-motivated behaviors via blockade of opioid receptors within the NACC and VTA, and under various dose conditions both reinforcer and neuroanatomical specificity can be observed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号