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   4071895篇
  免费   301671篇
  国内免费   10213篇
耳鼻咽喉   57472篇
儿科学   130349篇
妇产科学   111124篇
基础医学   568468篇
口腔科学   116940篇
临床医学   375170篇
内科学   789271篇
皮肤病学   91239篇
神经病学   337998篇
特种医学   158540篇
外国民族医学   1438篇
外科学   610007篇
综合类   91173篇
现状与发展   6篇
一般理论   1720篇
预防医学   325250篇
眼科学   94694篇
药学   301249篇
  11篇
中国医学   7983篇
肿瘤学   213677篇
  2018年   43660篇
  2017年   33584篇
  2016年   38155篇
  2015年   43062篇
  2014年   60631篇
  2013年   92053篇
  2012年   122325篇
  2011年   129809篇
  2010年   77837篇
  2009年   74421篇
  2008年   121826篇
  2007年   129406篇
  2006年   131159篇
  2005年   126801篇
  2004年   122204篇
  2003年   117813篇
  2002年   114657篇
  2001年   187044篇
  2000年   192541篇
  1999年   163295篇
  1998年   48482篇
  1997年   43265篇
  1996年   42903篇
  1995年   41614篇
  1994年   38635篇
  1993年   36150篇
  1992年   129755篇
  1991年   125526篇
  1990年   121333篇
  1989年   117243篇
  1988年   108364篇
  1987年   106745篇
  1986年   100817篇
  1985年   96580篇
  1984年   72638篇
  1983年   62031篇
  1982年   37354篇
  1981年   33615篇
  1979年   66748篇
  1978年   47233篇
  1977年   40022篇
  1976年   37493篇
  1975年   39595篇
  1974年   47988篇
  1973年   45810篇
  1972年   43106篇
  1971年   39924篇
  1970年   37307篇
  1969年   35274篇
  1968年   32451篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
The interventional endoscopy and new knowledge about the spontaneous course of the cholelithiasis have obtained a far-reaching influence on the indication for operation and the surgical approach. Now as ever the adequate therapy of the symptomatic cholecystolithiasis consists in the early cholecystectomy. Since in the natural course the risk of lethality is small the operation for indication depending on the age and the risk factors given must be made cautiously. This in a still higher degree concerns the asymptomatic cholelithiasis in which at present no general indication for operation is regarded necessary. Due to the low lethality of circa 1% the endoscopic papillotomy has become the therapeutic method of choice in residual and recurrent calculi after cholecystectomy, but also in risk patients with cholecystocholedocholithiasis. The endoscopic papillotomy with stone extraction before the operation suggests a decrease of the operation lethality of 3 to 5% after cholecystectomy with revision of the choledochus.  相似文献   
992.
As a result of policy changes and developments on the demand side, the importance of technology in primary health care will grow fast. An approach to the implementation of new technologies in primary health care is presented in this article. First we describe the main problems in Dutch primary health care. The second step is to identify new technologies which are becoming available. Subsequently, the interface between these problems and their possible technological resolution has to be found. The fact that a technological innovation appears to be a solution is not sufficient reason for introducing it. There are all kinds of reasons why an innovation that has proved useful in the hospital situation, for example, might be of doubtful use in primary health care. Accordingly, the next step is to assess whether a technological solution to a problem in primary health care is indeed an improvement. To acknowledge the particular situation of primary health care, a scheme has been developed that may be used to determine criteria of evaluation.  相似文献   
993.
Rats were killed after 6 weeks of continuous ingestion of the pneumotoxic alkaloid monocrotaline (2.2 mg/kg/day), the neutrophil elastase inhibitor SC39026 (60 mg/kg/day), or both. Pulmonary reactions were evaluated by light and electron microscopy. Lung endothelial function was monitored by angiotensin converting enzyme (ACE) activity, plasminogen activator (PLA) activity, and prostacyclin (PGI2) and thromboxane (TXA2) production. Lung hydroxyproline content was measured as an index of interstitial fibrosis. Cardiac right ventricular hypertrophy was determined by the right ventricle to the left ventricle plus septum weight ratio (RV/LV + S). Rats receiving SC39026 alone did not differ significantly from untreated control animals with respect to any of the quantitative endpoints, although rarefaction of Type I pneumocytes was observed in the electron micrographs of these animals. Monocrotaline-treated rats, in contrast, developed a significant increase in RV/LV + S, and exhibited pulmonary edema, inflammation, fibrosis, and muscularization and occlusive mural thickening of the pulmonary small arteries and arterioles. These monocrotaline-induced structural changes were accompanied by decreased lung ACE and PLA activities, and increased PGI2 and TXA2 production, and by an increase in lung hydroxyproline content. Cotreatment with SC39026 ameliorated the monocrotaline-induced pulmonary vascular wall thickening and the cardiac right ventricular hypertrophy. These data suggest that inappropriate neutrophil elastase activity contributes to monocrotaline pulmonary vasculopathy and hypertension. On the other hand, cotreatment with SC39026 had no significant effect on the severity of the monocrotaline-induced lung inflammatory reaction, the pulmonary endothelial dysfunction, or the increase in lung hydroxyproline content.  相似文献   
994.
We studied the parathyroid function in patients with advanced renal failure by determining their plasma concentrations of ionized calcium (iCa), intact parathyroid hormone (PTH) and its inactive metabolites (PTH-MM). The suppressibility of the parathyroidism was studied with a calcium infusion test. The intact PTH values of the nondialysis and dialysis patients did not statistically differ from each other. The concentrations of PTH-MM were, however, higher in the dialysis patients than in the nondialysis patients (p less than 0.05). The ratio of PTH-MM to intact PTH was lowest in healthy reference subjects and highest in dialysis patients (p less than 0.01), and did not correlate with the degree of intact PTH elevation in the patient groups. The calcium infusion test was carried out on 15 patients. All showed suppression in the elevated plasma intact PTH concentration and in 6 the intact PTH value normalized. The PTH-MM value did not normalize in any of the patients. During oral calcium treatment the degree of intact PTH suppression at an achieved concentration of plasma iCa was predictable from the infusion test. Three patients were parathyroidectomized after the calcium infusion test. In 2 of these elevated intact PTH normalized within 24 h while in 1 no change took place. In this latter case on clinical improvement was noted. We conclude that the determination of plasma intact PTH concentration especially of combined with plasma iCa value is a reliable means of studying the hyperparathyroidism associated with chronic renal failure.  相似文献   
995.
996.
997.
998.
999.
1000.
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