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   2625823篇
  免费   188170篇
  国内免费   7639篇
耳鼻咽喉   34653篇
儿科学   86277篇
妇产科学   72276篇
基础医学   368520篇
口腔科学   70398篇
临床医学   239046篇
内科学   522544篇
皮肤病学   62985篇
神经病学   216836篇
特种医学   101437篇
外国民族医学   736篇
外科学   392682篇
综合类   50912篇
现状与发展   5篇
一般理论   1012篇
预防医学   200339篇
眼科学   57581篇
药学   190809篇
  10篇
中国医学   5371篇
肿瘤学   147203篇
  2021年   20717篇
  2019年   21340篇
  2018年   30172篇
  2017年   23225篇
  2016年   26891篇
  2015年   30327篇
  2014年   41602篇
  2013年   62188篇
  2012年   82853篇
  2011年   87170篇
  2010年   52479篇
  2009年   50423篇
  2008年   81320篇
  2007年   86385篇
  2006年   88039篇
  2005年   84156篇
  2004年   81005篇
  2003年   78215篇
  2002年   75378篇
  2001年   128924篇
  2000年   131794篇
  1999年   110985篇
  1998年   31701篇
  1997年   28270篇
  1996年   28548篇
  1995年   27738篇
  1994年   25383篇
  1993年   23700篇
  1992年   85472篇
  1991年   81853篇
  1990年   79063篇
  1989年   76327篇
  1988年   69718篇
  1987年   68234篇
  1986年   63775篇
  1985年   60784篇
  1984年   45173篇
  1983年   38125篇
  1982年   22633篇
  1981年   20141篇
  1979年   39110篇
  1978年   27593篇
  1977年   23378篇
  1976年   21622篇
  1975年   22927篇
  1974年   26931篇
  1973年   25493篇
  1972年   23871篇
  1971年   22056篇
  1970年   20312篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
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   
992.
993.
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   
994.
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   
995.
996.
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   
997.
The acute recognition and management of CHF is challenging. A basic understanding of the determinants of cardiac performance and myocardial O2 consumption along with the pathophysiology of CHF is essential knowledge for the physician undertaking to treat this serious disorder. The basic value of the patient history and physical examination along with assessment of noninvasive tests remains unquestioned, but in addition much relevant and sophisticated information can be gained by invasive hemodynamic monitoring. The cardiopulmonary profile generated by such monitoring allows the physician to use specific hemodynamic and circulatory data for the purpose of manipulating these variables favorably for the heart and circulation. A wide array of therapeutic options is currently available, but, in general, respiratory support and pharmacotherapy are the mainstays of treatment. The traditional agents like digitalis and diuretics have assumed a lesser role during the last decade because of the availability of potent new vasodilator and inotropic agents. In addition, certain mechanical, procedural, and surgical options can be used if circumstances are urgent. In the final analysis, physicians who manage these patients must possess strong cognitive skills but also the clinical reflexes to carry them out: for every hemodynamic and circulatory action, they must be prepared to counter quickly and decisively with a clinical reaction which utilizes these principles to optimize cardiac function. It is hoped that the strategies presented in this article will allow them to perform in such a manner.  相似文献   
998.
K M Klueber 《The Anatomical record》1987,219(4):370-3, 429-33
Although the reinnervation of muscle grafts has been demonstrated, the question remains as to the source of neurons reinnervating the graft. A muscle graft could be reinnervated by its original neurons (neural neurotization) or by sprouting of axons which supply the intact myofibers of surrounding muscles (muscle neurotization). The objective of this study was to evaluate the role of muscle neurotization in the reinnervation process using both horseradish peroxidase and fluorescent tracers. Observations from 20 muscle grafts indicate that the neurons reinnervating the grafts are from the original motor neuron pool. Thus muscle neurotization may not occur during the reinnervation process.  相似文献   
999.
Preclinical and clinical investigations currently underway are employing novel strategies for combining vaccines with conventional and experimental anticancer therapies. To date, the FDA has not approved a therapeutic cancer vaccine. However, the results of recent investigations suggest an increasing role for vaccines in new models of combination therapy for many types of cancer. This article reviews and discusses therapeutic cancer strategies that employ vaccines in combination with local radiation, chemotherapy, hormone therapy, and anti-CTLA-4 mAb. Preclinical studies have shown that certain anticancer agents have immune modulatory effects that result in up-regulation of surface expression of MHC molecules, tumor-associated antigens, or Fas on malignant cells, rendering them more susceptible to immune destruction. Preliminary results of clinical studies using combination strategies have demonstrated a postvaccination antigen cascade, prolonged time to disease progression, and improved overall survival. Several larger randomized trials are ongoing, and more are required to support these findings.  相似文献   
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