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   304508篇
  免费   23108篇
  国内免费   7230篇
耳鼻咽喉   3709篇
儿科学   6797篇
妇产科学   6312篇
基础医学   36386篇
口腔科学   6214篇
临床医学   33222篇
内科学   57724篇
皮肤病学   4371篇
神经病学   24207篇
特种医学   10370篇
外国民族医学   53篇
外科学   39514篇
综合类   21560篇
现状与发展   23篇
一般理论   219篇
预防医学   22378篇
眼科学   8170篇
药学   24818篇
  114篇
中国医学   6724篇
肿瘤学   21961篇
  2023年   2174篇
  2022年   4533篇
  2021年   8202篇
  2020年   5726篇
  2019年   6490篇
  2018年   7278篇
  2017年   6105篇
  2016年   6113篇
  2015年   8608篇
  2014年   11765篇
  2013年   14753篇
  2012年   21380篇
  2011年   22991篇
  2010年   14240篇
  2009年   12385篇
  2008年   19203篇
  2007年   19908篇
  2006年   19007篇
  2005年   18762篇
  2004年   16329篇
  2003年   15354篇
  2002年   14201篇
  2001年   4568篇
  2000年   3962篇
  1999年   4224篇
  1998年   3619篇
  1997年   3222篇
  1996年   2682篇
  1995年   2523篇
  1994年   2305篇
  1993年   1848篇
  1992年   1925篇
  1991年   1751篇
  1990年   1501篇
  1989年   1383篇
  1988年   1360篇
  1987年   1155篇
  1986年   1188篇
  1985年   1198篇
  1984年   1404篇
  1983年   1340篇
  1982年   1731篇
  1981年   1605篇
  1980年   1483篇
  1979年   925篇
  1978年   1017篇
  1977年   883篇
  1976年   771篇
  1975年   613篇
  1974年   686篇
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
991.
Eighteen healthy adult volunteers completed an open-label, four-way crossover study designed to determine the bioequivalency of 160-mg cibenzoline [2-(2,2-diphenylcyclopropyl)-4,5-dihydro-1H-imidazole] capsules and tablets, their relative bioavailability compared with an oral solution of the drug, as well as the absolute bioavailability of these dosage forms compared with an intravenous infusion of the drug. Blood samples obtained at specified times after drug administration were assayed for cibenzoline by HPLC, and pharmacokinetic parameters were estimated from the resulting plasma concentration-time profiles. Comparisons were made between the tablet and capsule to assess bioequivalency, between the solid dosage forms and a solution to assess relative bioavailability, and between the oral forms and an intravenous infusion to assess absolute bioavailability. The pharmacokinetic parameters for each oral dosage form were similar and ratios of mean parameters indicated that the solid dosage forms were bioequivalent and completely bioavailable relative to an oral solution. The ratios of the area under the plasma concentration-time profiles (AUC) for the capsule, tablet, and oral solution to that of the intravenous infusion were 0.85, 0.83, and 0.86, respectively, indicating that orally administered cibenzoline has an absolute bioavailability of approximately 85%.  相似文献   
992.
993.
感应式人工耳蜗装置将声音信息转变并处理为适当的电信号之后,采用电磁感应的方式将此信号送至植入全聋患者内耳耳蜗靠近听神经纤维的作用电极上,刺激神经发放冲动,使全聋患者恢复音感。本装置经临床全聋患者使用,取得较满意效果。  相似文献   
994.
A representative sample of 1650 children randomly selected in the 6-15-yr-old schoolchild population of Strasbourg was examined by well-calibrated examiners. The prevalence of caries was determined with the DMFT, DMFS and dft indices using bitewing radiographs. Plaque, calculus and gingival indices were also determined. The results obtained were compared with the initial study of 1974 performed in Strasbourg using the same epidemiologic methods. Whereas no important variations were observed in caries prevalence of primary teeth, a significant reduction of caries activity was observed in DMFT and DMFS indices in all age groups. There was a reduction of these two indices of respectively 32% and 33% in the 12-yr-old children. The reduction was the most significant on approximal surface lesions. A statistically significant decrease of the calculus and gingival indices was also observed between 1974 and 1984. A less significant decrease was observed for the plaque index.  相似文献   
995.
996.
Pulsed Doppler and two-dimensional echocardiography were used to determine the haemodynamic effects of rectal methohexitone in 12 children 32.4 +/- 3.8 months old and weighing 13.3 +/- 1.1 kg (mean +/- SEM). Heart rate, blood pressure and echocardiographic measurements of cardiac output, stroke volume and left ventricular end-diastolic and end-systolic volumes were obtained prior to the induction of anaesthesia. Anaesthesia was induced with 25 mg.kg-1 two per cent rectal methohexitone. Immediately following the onset of sleep all cardiovascular measurements were repeated. Following the induction of anaesthesia with rectal methohexitone there was a significant increase in heart rate. Blood pressure, cardiac index, stroke volume and ejection fraction were unchanged. It is concluded that rectal administration of two per cent methohexitone for the induction of anaesthesia in healthy paediatric patients has minimal haemodynamic effect.  相似文献   
997.
Over twelve alkaloids were delected in the roots ofPanax ginseng C.A. Meyer. Among them three alkaloids were isolated and were identified as N9-formylharman, ethyl β-carboline-1-carboxylate and perlolyrine on the basis of spectroscopic studies.  相似文献   
998.
999.
1000.
In the presence of ATP, MgCl2, and CoASH, somal plasma membranes isolated from rat cerebral cortex were active in transferring arachidonic acid to phosphatidylinositols, phosphatidylcholines, and triacylglycerols. Ethanol (350-525 mM) added to the incubation mixture inhibited arachidonic acid incorporation into phospholipids, while it enhanced the incorporation into triacylglycerols. Under these conditions, ethanol was found to react with arachidonic acid to form arachidonoyl ethyl ester. The incorporation of labeled arachidonic acid into glycerolipids as well as the synthesis of ethyl esters required the presence of ATP and CoASH for maximal activity. Nevertheless, each uptake process exhibited a unique pH profile. The esterification of arachidonic acid was not specific for ethanol as other aliphatic alcohols (e.g., propanol and butanol) were also able to react with labeled arachidonic acid to form the respective esters. Somal plasma membranes isolated from mice after chronic ethanol administration showed an increase in arachidonoyl transfer to both phospholipids and triacylglycerols. When these membranes were challenged with ethanol (325 mM), those isolated from the chronic ethanol group showed a greater increase in the labeling of triacylglycerols and ethyl esters than those from controls. Thus, different acyltransferases exhibite different responses to the effects of ethanol in vitro and in vivo.  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