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   158082篇
  免费   11105篇
  国内免费   621篇
耳鼻咽喉   1768篇
儿科学   3907篇
妇产科学   2611篇
基础医学   20925篇
口腔科学   3387篇
临床医学   15513篇
内科学   33482篇
皮肤病学   3244篇
神经病学   14585篇
特种医学   6967篇
外国民族医学   14篇
外科学   25199篇
综合类   1953篇
一般理论   109篇
预防医学   11752篇
眼科学   3295篇
药学   10130篇
中国医学   238篇
肿瘤学   10729篇
  2023年   805篇
  2022年   1181篇
  2021年   3373篇
  2020年   2080篇
  2019年   3118篇
  2018年   3594篇
  2017年   2798篇
  2016年   3137篇
  2015年   3586篇
  2014年   5092篇
  2013年   6851篇
  2012年   10340篇
  2011年   11005篇
  2010年   6308篇
  2009年   6016篇
  2008年   9747篇
  2007年   10189篇
  2006年   10097篇
  2005年   10143篇
  2004年   9310篇
  2003年   8619篇
  2002年   8267篇
  2001年   2149篇
  2000年   1840篇
  1999年   2126篇
  1998年   1925篇
  1997年   1551篇
  1996年   1334篇
  1995年   1251篇
  1994年   1125篇
  1993年   1015篇
  1992年   1293篇
  1991年   1191篇
  1990年   1031篇
  1989年   972篇
  1988年   913篇
  1987年   885篇
  1986年   886篇
  1985年   868篇
  1984年   926篇
  1983年   796篇
  1982年   961篇
  1981年   860篇
  1980年   730篇
  1979年   654篇
  1978年   649篇
  1977年   534篇
  1976年   514篇
  1974年   514篇
  1973年   452篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
The vasomotor response of native human collateral vessels to pharmacologic or hemodynamic vasodilatory stimuli is not well known. We describe a case where retrograde collateral flow velocity was measured both at baseline and following selected hemodynamic and pharmacologic interventions. This index case represents the first in a series of potential human physiologic studies designed to address questions pertaining to control of collateral blood supply in humans. © 1993 Wiley-Liss, Inc.  相似文献   
112.
Monte Carlo simulation was used to assess the effects of several intervention strategies on coronary heart disease mortality rates in a Finnish and a North American cohort. Lowering total serum cholesterol by 4%, smoking by 15%, and diastolic blood pressure by 3% for the whole cohort would be expected to reduce the incidence of non-fatal myocardial infarction by at least 13% and coronary heart disease deaths by at least 18%. Lowering serum cholesterol by 34%, diastolic blood pressure to 90 mmHg, and reducing smoking by 20% in the subset of the population with all three risk factors in the highest quartile would result in a 6-8% reduction in non-fatal myocardial infarction and a 2-9% reduction in deaths from coronary heart disease in these cohorts. These data demonstrate that in populations with a relatively high incidence of heart disease, treating the entire population will produce larger effects than focusing only on high-risk populations.  相似文献   
113.
External fixation is an apparently simple and therefore highly fascinating method for the stabilization of fractures.Minimally invasive incisions guarantee that regional soft tissue perfusion is conserved after trauma,which makes it the best procedure for stabilization of fractures combined with severe soft tissue damage.However, modern trauma surgery is subject to cyclical trends in the same way as fashion is; noninternal devices are currently barely tolerated.The literature suggests that specialists are virtually competing to see who can stabilize fractures with the most severe soft tissue damage by internal procedures – with the best results, of course. It seems, then, that times are hard for external fixation, but we still believe that for fractures with severe soft tissue damage external fixation still brings a lot of benefit to the patient.  相似文献   
114.
115.
116.
117.
118.
PURPOSE: This study was undertaken to clarify the importance of bleeding vascular ectasia of the colon as the etiology of massive lower gastrointestinal hemorrhage in patients 40 years of age or younger. METHODS: An otherwise healthy 21-year-old male was admitted to a tertiary medical center with massive lower gastrointestinal hemorrhage. Technetium-labeled red blood cell scan, selective visceral angiography, and colonoscopy identified the source of bleeding as vascular abnormality of the descending colon. Segmental colonic resection was performed. RESULTS: Histologic review of the specimen demonstrated a vascular ectasia. The patient recovered uneventfully and has had no further stigmata of hemorrhage. A review of the literature was undertaken to make clear the significance of vascular ectasia as the source for massive colonic hemorrhage in the young adult. CONCLUSION: This is the first report that documents histologically a vascular ectasia as the source of massive lower gastrointestinal hemorrhage in an otherwise healthy patient less than 40 years of age. Vascular ectasia is an uncommon cause of lower gastrointestinal hemorrhage in the young adult.The Chief, Bureau of Medicine and Surgery, Navy Department, Washington, DC, Clinical Investigation Program sponsored this report #84-16-1968-532, as required by HSETCINST 6000.41A. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government.  相似文献   
119.
Alpha-Melanocyte-stimulating hormone (MSH) is a potent anti-inflammatory agent in many models of inflammation, suggesting that it inhibits a critical step common to different forms of inflammation. We showed previously that alpha-MSH inhibits nitric oxide (NO) production in cultured macro-phages. To determine how alpha-MSH acts in vivo, we induced acute hepatic inflammation by administering endotoxin (LPS) to mice pretreated with Corynebacterium parvum, alpha-MSH prevented liver inflammation even when given 30 min after LPS administration. To determine the mechanisms of action of alpha-MSH, we tested its influence on NO, infiltrating inflammatory cells, cytokines, and chemokines. Alpha-MSH inhibited systemic NO production, hepatic neutrophil infiltration, and increased hepatic mRNA abundance for TNF alpha, and the neutrophil and monocyte chemokines (KC/IL-8 and MCP-1). We conclude that alpha-MSH prevents LPS-induced hepatic inflammation by inhibiting production of chemoattractant chemokines which then modulate infiltration of inflammatory cells. Thus, alpha-MSH has an effect very early in the inflammatory cascade.  相似文献   
120.
OBJECTIVES: The incidence of bacterial microleakage, pulp inflammation and necrosis associated with dentine etching treatments prior to restoration are not known. Consequently, to resolve some of the controversy surrounding the effects and importance of vital dentine etching, the authors investigated these factors. METHODS: 110 standardised class V cavities were cut into buccal dentine, without exposing the pulp of teeth scheduled for extraction for orthodontic reasons. Cavities were either left unetched, or etched with the non-equivalent treatments of phosphoric acid gel for 60s or Ethylenediaminetetraacetic acid (EDTA) for 30s, prior to placement of composite resin. Teeth were collected and pulp responses were evaluated according to ISO guidelines, using pathohistomorphometric analysis and ANOVA statistics. RESULTS: Etching was found to be correlated to bacterial microleakage (p=0.0001) and tertiary dentine formation (p=0.0023). Bacterial microleakage was correlated to inflammatory activity (p=0.0001). The frequency of bacterial microleakage was: no etching (65%), EDTA (51%) and phosphoric acid (PA) (20%). SIGNIFICANCE: Vital dentine etching treatment is of extreme importance for the placement of RC to minimise bacterial microleakage. PA etching proved to be more effective at preventing bacterial microleakage than non-etching, and etching with EDTA.  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