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   4096398篇
  免费   274281篇
  国内免费   11704篇
耳鼻咽喉   55534篇
儿科学   133147篇
妇产科学   111287篇
基础医学   574568篇
口腔科学   115654篇
临床医学   384085篇
内科学   785808篇
皮肤病学   90696篇
神经病学   337127篇
特种医学   154694篇
外国民族医学   1249篇
外科学   596304篇
综合类   91610篇
现状与发展   6篇
一般理论   1662篇
预防医学   333150篇
眼科学   91895篇
药学   299222篇
  101篇
中国医学   8588篇
肿瘤学   215996篇
  2019年   33546篇
  2018年   45396篇
  2017年   34633篇
  2016年   39430篇
  2015年   44465篇
  2014年   61723篇
  2013年   94629篇
  2012年   125652篇
  2011年   133741篇
  2010年   80255篇
  2009年   75918篇
  2008年   124177篇
  2007年   131869篇
  2006年   133720篇
  2005年   128875篇
  2004年   123868篇
  2003年   119264篇
  2002年   115080篇
  2001年   185398篇
  2000年   190745篇
  1999年   161084篇
  1998年   48091篇
  1997年   42574篇
  1996年   42580篇
  1995年   41194篇
  1994年   38222篇
  1993年   35906篇
  1992年   127991篇
  1991年   124236篇
  1990年   120665篇
  1989年   116024篇
  1988年   106956篇
  1987年   105188篇
  1986年   99467篇
  1985年   95398篇
  1984年   71897篇
  1983年   61146篇
  1982年   36723篇
  1981年   32900篇
  1979年   65094篇
  1978年   46587篇
  1977年   39099篇
  1976年   36886篇
  1975年   39055篇
  1974年   46844篇
  1973年   44902篇
  1972年   42008篇
  1971年   39112篇
  1970年   36175篇
  1969年   34157篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
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   
962.
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   
963.
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   
964.
965.
966.
967.
968.
969.
A series of 6-fluoro- and 6,8-difluoro-7-(azole substituted)-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids were prepared. Structure-activity relationship studies indicated that the antibacterial potency was better when the 6,8-substituents were fluorine atoms and the 7-substituent was either 1-imidazolyl, 20, or 4-methyl-1-imidazolyl, 25. From the results of studies on pharmacokinetic profile and toxicity, 20 and 25 were found to possess excellent antibacterial activities and to show high blood levels after oral administration to mice with low toxicity.  相似文献   
970.
Rolled finger gloves were used as ring tourniquets on a case of amputation injury of bilateral thumbs. Necrosis of soft tissue of the right thumb occurred due to mistakenly prolonged use of the tourniquet. Later the patient successfully underwent a toe-to-thumb transfer (modified wraparound procedure). The precautions in using finger tourniquets are stressed.  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