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   2088467篇
  免费   149972篇
  国内免费   6132篇
耳鼻咽喉   27974篇
儿科学   67691篇
妇产科学   58479篇
基础医学   302898篇
口腔科学   57967篇
临床医学   193284篇
内科学   405499篇
皮肤病学   42800篇
神经病学   172511篇
特种医学   79085篇
外国民族医学   669篇
外科学   304036篇
综合类   44738篇
现状与发展   1篇
一般理论   722篇
预防医学   168840篇
眼科学   46759篇
药学   152004篇
  6篇
中国医学   4595篇
肿瘤学   114013篇
  2019年   16819篇
  2018年   23961篇
  2017年   18442篇
  2016年   20203篇
  2015年   22587篇
  2014年   31264篇
  2013年   48774篇
  2012年   66234篇
  2011年   70762篇
  2010年   41510篇
  2009年   38222篇
  2008年   65763篇
  2007年   69675篇
  2006年   69650篇
  2005年   67666篇
  2004年   64524篇
  2003年   62040篇
  2002年   60612篇
  2001年   92733篇
  2000年   95912篇
  1999年   80285篇
  1998年   22856篇
  1997年   20796篇
  1996年   20406篇
  1995年   19260篇
  1994年   18176篇
  1993年   17133篇
  1992年   63098篇
  1991年   61427篇
  1990年   59726篇
  1989年   57084篇
  1988年   52928篇
  1987年   51836篇
  1986年   49474篇
  1985年   47422篇
  1984年   35869篇
  1983年   30516篇
  1982年   18512篇
  1979年   32728篇
  1978年   23193篇
  1977年   19311篇
  1976年   18759篇
  1975年   19643篇
  1974年   23776篇
  1973年   23087篇
  1972年   21517篇
  1971年   19980篇
  1970年   18774篇
  1969年   17345篇
  1968年   16575篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A longitudinal study was conducted to investigate changes in women's mental and physical health around the time of childbirth, and to determine whether health was related to length of maternity leave. Thirty-seven married, employed first-time mothers completed questionnaires during pregnancy, and again at 6 weeks, 3 months, and 6 months postpartum. Results showed that, from pregnancy to the 6th postpartum month, the number of days that mothers were ill because of infections steadily increased. In addition, depressive symptoms for new mothers rose from pregnancy to the 6th week postpartum, and declined thereafter. For women who did not return to work during the period of the study, a significant decline in depressive symptoms was observed from the prenatal period through the 6th postpartum month. These findings demonstrate significant changes in mental and physical health for this group of first-time mothers.  相似文献   
992.
Twenty-two days after administration by intravenous bolus, of 50 mg of adriamycin to several patients we found concentrations of adriamycin and adriamycinol of the order of 100 pcg/ml. In theory, however, with a terminal half-life of 30 h, the plasma levels of adriamycin and adriamycinol should be close to 0.1 pcg/ml. Further pharmacokinetic investigation was therefore necessary. We have retained for this study nine male patients, aged between 53 and 69 years who received 25 to 50 mg of adriamycin by slow intravenous injection. The HPLC method permitted the detection of 50 pcg/ml of adriamycin and adriamycinol, with the possibility of monitoring their elimination during 120 h (and in one case during 160 h). The terminal half-lives of elimination estimated in 8 patients were respectively 110 +/- 52 h for adriamycin and 92 h 50 min +/- 43 h for adriamycinol. Surface ratios under adriamycinol curves against calculated adriamycin was 1.10 +/- 0.26. Plasma levels found during the To in certain patients correspond to the end of the drug elimination of the previous treatment. It is difficult with a half-life to 110 h to predict the effects of residual concentrations of adriamycin and adriamycinol.  相似文献   
993.
Following an encephalopathic illness, a 13-year-old Chinese boy had a partial form of Klüver-Bucy syndrome with emotional disturbance, recent memory loss, hypersexuality, and polyphagia. Other unusual features included narcolepsy, polydipsia, and polyuria. Virologic studies failed to incriminate the etiologic agent, including herpes simplex virus. Brain biopsy of the frontal lobe demonstrated Alzheimer type II astrocytosis.  相似文献   
994.
Biodegradable controlled-release microsphere systems made with the biocompatible biodegradable polyester excipient poly [DL lactide-co-glycolide] constitute an exciting new technology for drug delivery to the central nervous system (CNS). The present study describes functional observations indicating that implantation of dopamine (DA) microspheres encapsulated within two different polymer excipients into denervated-striatal tissue assures a prolonged release of the transmitter in vivo. Moreover, in this regard, the results show that there were clear cut temporal differences in the effect of the two DA microsphere formulations compared in this study, probably reflecting variations in the actual composition (i.e., lactide to glycolide ratio) of the two copolymer excipients examined. This technology has considerable potential for basic research with possible clinical application.  相似文献   
995.
A quantitative assay for ALZ-50 immunoreactivity was evaluated in samples of superior temporal gyrus taken at autopsy from 13 Alzheimer patients and 11 controls. The assayable immunoreactivity appears to be stable for at least 24 hours postmortem but was lost with formalin fixation. The mean value of the Alzheimer patients was tenfold higher than that of the controls (P less than .002). The values of four Alzheimer samples overlapped with the low levels seen in controls, but no controls had elevated levels. In this sample population, therefore, the assay had a sensitivity of 69% and specificity of 100%.  相似文献   
996.
A case of an ameloblastoma diagnosed about 3 1/2 years after removal of an impacted mandibular 3rd molar is presented. The pre-operative radiographs, though poor in quality, showed an ill-defined radiolucency in relation to the tooth. This feature was not apparent to the examiners at the time of first presentation. Despite unfavourable working conditions in developing countries, a high level of suspicion should be maintained to avoid serious sequelae at a later stage.  相似文献   
997.
998.
999.
Single or combined monoclonal antibodies (McAbs) Zh53, Zh820, and Zh2-1 have been used to eliminate malignant clonogenic cells from human bone marrow. The test of cytotoxicity showed that all of these McAbs could express high specific cytotoxic action against HL-60 cells and were selectively complement-dependent cytotoxic to various types of fresh leukemic cells. Clonogenic assay detected that single treatment with antibody and rabbit complement (RC) could reduce clonogenic units of HL-60 cells by more than 2 logs and two treatments reduced clonogenic units by more than 4 logs. However, combination of 2 McAbs could reduce clonogenic units by 4-5 logs. The data suggest that multiple treatments with McAbs and RC or a combination of 2 McAbs are more effective than a single treatment in eliminating clonogenic tumor cells. Treatment of normal human bone marrow with Zh53, Zh2-1 and RC did not produce a loss of normal CFU-GM, but treatment with Zh820 reduced the clonic units of normal CFU-GM by 24%.
  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