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   2396174篇
  免费   181540篇
  国内免费   4876篇
耳鼻咽喉   33442篇
儿科学   79625篇
妇产科学   69070篇
基础医学   345371篇
口腔科学   66610篇
临床医学   211610篇
内科学   470226篇
皮肤病学   53612篇
神经病学   192066篇
特种医学   92191篇
外国民族医学   793篇
外科学   363301篇
综合类   54079篇
现状与发展   4篇
一般理论   742篇
预防医学   184570篇
眼科学   55085篇
药学   175529篇
  2篇
中国医学   5208篇
肿瘤学   129454篇
  2018年   25235篇
  2017年   19160篇
  2016年   21702篇
  2015年   24599篇
  2014年   34453篇
  2013年   51755篇
  2012年   70456篇
  2011年   75105篇
  2010年   44360篇
  2009年   42050篇
  2008年   70766篇
  2007年   75668篇
  2006年   76658篇
  2005年   74593篇
  2004年   71716篇
  2003年   68790篇
  2002年   67189篇
  2001年   113194篇
  2000年   115928篇
  1999年   97335篇
  1998年   27817篇
  1997年   25060篇
  1996年   25182篇
  1995年   23888篇
  1994年   21982篇
  1993年   20668篇
  1992年   75809篇
  1991年   73492篇
  1990年   71620篇
  1989年   69057篇
  1988年   63758篇
  1987年   62505篇
  1986年   58982篇
  1985年   56300篇
  1984年   42502篇
  1983年   36475篇
  1982年   21954篇
  1981年   19520篇
  1979年   38925篇
  1978年   27565篇
  1977年   23274篇
  1976年   22112篇
  1975年   23596篇
  1974年   28079篇
  1973年   27069篇
  1972年   25579篇
  1971年   23538篇
  1970年   22161篇
  1969年   20982篇
  1968年   19729篇
排序方式: 共有10000条查询结果,搜索用时 33 毫秒
991.
992.
Lyme arthritis     
Evanescent arthralgias and myalgias are common early symptoms of Lyme disease. Transient, intermittent episodes of monoarticular, oligoarticular, or sometimes migratory polyarticular arthritis, lasting weeks to months, with disease-free intervals, are frequently observed in untreated patients with erythema chronicum migrans. A minority of patients develop chronic joint involvement, most commonly affecting the knee. Antibiotic therapy given during erythema chronicum migrans is often protective with regard to late joint manifestations. In chronic Lyme arthritis, however, the response to antibiotics is variable.  相似文献   
993.
Plasma D-dimer (DD) and thrombin--antithrombin III complex (TAT) were measured with ELISAs in 99 patients investigated by 102 ventilation--perfusion lung scintigraphy because of suspected pulmonary embolism. High-probability lung scan was associated with increased DD (more than 500 ng/ml) and TAT (more than 4.1 ng/ml) levels (sensitivity of 100 and 70%, respectively). The corresponding figures of specificity were 81 and 42%. In the 56 patients with low-probability or indeterminate probability scans, 31 (55%) had DD concentrations of less than 500 ng/ml. These preliminary data suggest that a plasma DD concentration of less than 500 ng/ml might rule out the diagnosis of pulmonary embolism in suspected patients with an inconclusive lung scanning.  相似文献   
994.
995.
The process of data entry and initial analysis to locate data errors is described. Basic terms are defined and a simple method of entering data by using word processing software is illustrated. Data checking is done by using visual check of the raw data. Statistical programs are then used to locate possible data errors by finding data points (outliers) that are very different from the average. Special graphic output of statistical programs, scatterplots and box and whisker plots can be used to further locate questionable data. Examples of data entry forms and annotated step by step data cleaning with the use of inexpensive programs for personal computers are presented.  相似文献   
996.
A patient who had right and left atrial membranes was examined. The diagnosis and the hemodynamic significance of both membranes were detailed by transesophageal echocardiography and were confirmed by magnetic resonance imaging. Transesophageal imaging was found to be superior to routine echocardiography in visualization of these atrial structures.  相似文献   
997.
Critically ill cardiac patients often undergo mechanical ventilation. The interplay between pulmonary and cardiac mechanics is complicated and in many cases may result in impaired transfer of O2 from the atmosphere to the tissues. This article addresses the principles of pulmonary and peripheral gas exchange, as well as the mechanical effects of respiration on the circulation.  相似文献   
998.
Synovial fluid phospholipase A2s and inflammation.   总被引:1,自引:1,他引:0       下载免费PDF全文
The activation of phospholipase A2 is believed to have an important role in the inflammatory process owing to its induction of eicosanoids, platelet activating factor, and other mediators. Soluble phospholipase A2 has been associated with exudates in different inflammatory conditions. In this review the general physiology and control of this enzyme and, in particular, the most recent findings on human synovial fluid phospholipase A2s are discussed.  相似文献   
999.
A variety of nutritional factors influence the bioavailability of calcium and increase a woman's risk of osteoporosis. Eight healthy women completed an 8-week metabolic study designed to investigate the effect of nonalcoholic carbonated beverage consumption on calcium metabolism. Compared with women receiving a control diet, women consuming a diet high in nonalcoholic carbonated beverages demonstrated similar mean serum levels of calcium, ionized calcium, phosphorus, alkaline phosphatase, parathyroid hormone, 1,25-dihydroxyvitamin D3, and osteocalcin. Twenty-four-hour urine volume, creatinine clearance, calcium-creatinine ratio, and phosphorus-creatinine ratio were similar during consumption of the diet high in nonalcoholic carbonated beverages and the control diet. Twenty-four-hour cyclic adenosine monophosphate-creatinine ratio was significantly lower in women consuming the diet high in nonalcoholic carbonated beverage compared with women receiving the control diet (342 +/- 27.4 nmol/mmol vs 409 +/- 22.1 nmol/mmol). Consumption of a diet high in nonalcoholic carbonated beverages on a short-term basis does not appear to affect adversely the serum or urinary markers of calcium metabolism.  相似文献   
1000.
This study was conducted to test the effects of preadmission preparation on parent and child psychological upset at the time of tonsillectomy surgery, on child postsurgery behavior, and on parental compliance with home care instructions. Forty children aged 3 to 11 years who underwent tonsillectomy on an outpatient basis were studied. No significant differences were found in parent and child behaviors of those people in the preparation group compared with those in the nonpreparation group. Parental reports of home care revealed that the majority of parents did not follow at least one half of the physicians' home care instructions. The findings of the study indicate the need to further examine factors associated with parental compliance with home care instructions.  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