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   2921831篇
  免费   209620篇
  国内免费   4895篇
耳鼻咽喉   40985篇
儿科学   94291篇
妇产科学   80209篇
基础医学   426947篇
口腔科学   80614篇
临床医学   261082篇
内科学   566071篇
皮肤病学   63931篇
神经病学   231036篇
特种医学   110792篇
外国民族医学   801篇
外科学   443710篇
综合类   61685篇
现状与发展   12篇
一般理论   1053篇
预防医学   226130篇
眼科学   68388篇
药学   216198篇
  11篇
中国医学   5749篇
肿瘤学   156651篇
  2019年   23280篇
  2018年   32203篇
  2017年   24482篇
  2016年   27206篇
  2015年   30708篇
  2014年   43521篇
  2013年   65713篇
  2012年   90170篇
  2011年   96003篇
  2010年   57244篇
  2009年   54135篇
  2008年   90504篇
  2007年   96264篇
  2006年   97392篇
  2005年   94618篇
  2004年   90537篇
  2003年   87289篇
  2002年   84982篇
  2001年   131598篇
  2000年   135059篇
  1999年   114054篇
  1998年   33090篇
  1997年   29337篇
  1996年   29498篇
  1995年   27717篇
  1994年   25684篇
  1993年   24247篇
  1992年   88778篇
  1991年   86193篇
  1990年   84415篇
  1989年   81283篇
  1988年   74918篇
  1987年   73668篇
  1986年   69375篇
  1985年   66435篇
  1984年   49659篇
  1983年   42353篇
  1982年   25317篇
  1979年   45838篇
  1978年   32668篇
  1977年   27243篇
  1976年   26004篇
  1975年   28121篇
  1974年   33890篇
  1973年   32377篇
  1972年   30358篇
  1971年   28572篇
  1970年   26641篇
  1969年   25237篇
  1968年   23426篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Pure motor hemiplegia (PMH) is, in most cases, caused by a lacunar infarction. However, pure motor monoparesis (PMM), i.e., isolated motor involvement with spasticity in one limb, has drawn little attention. We studied prospectively 5 patients with PMM and found that it was always due to a mass lesion in the contralateral superficial cerebral hemisphere. Our observation suggests that PMM should not be regarded as simply a variant of PMH.  相似文献   
942.
The purpose of the study was to compare an interview measure of quality of object relations to questionnaire and interview measures of recent interpersonal functioning with respect to the prediction of therapeutic alliance and psychotherapy outcome. The sample consisted of 64 patients who had received approximately 20 sessions of short-term individual psychotherapy within a controlled, clinical-trial investigation. Ratings of therapeutic alliance were provided independently by the patient and the therapist after each session. Outcome measures, which were provided by three sources (patient, therapist, and independent assessor), covered the areas of interpersonal functioning, psychiatric symptomatology, self-esteem, and life satisfaction. Quality of object relations, which characterizes the patient's lifelong pattern of relationships, was the best predictor. It was significantly related to patient-rated and therapist-rated therapeutic alliance and to patient improvement of both general symptomatology and specific target problems. The study also replicated previous studies that have reported significant relationships between therapeutic alliance and therapy outcome. The advantages of pretherapy predictors of therapy outcome, such as quality of object relations, are discussed.  相似文献   
943.
944.
We applied a specific cytochemical reaction to characterize the glycoconjugates produced by goblet and non-goblet epithelial cells of normal human conjunctiva. For this purpose we utilized the lectins, proteins of vegetal origin, which are extremely sensitive in binding glycosidic residues. In particular, we used WGA, PNA, SBA and ConA conjugated with colloidal gold as ultrastructural marker for Transmission Electron Microscopy. This technique allowed us also to perform a quantitative analysis, by counting colloidal gold particles present on mucus granules. In this way we analyzed the content both of goblet and non-goblet epithelial cells. In the former, WGA, PNA, SBA and ConA receptors, here reported in decreasing density, were present. In the latter WGA was always positive, SBA and PNA sometimes were negative, ConA was always negative. We speculate the different contribution to mucus production by these two sources may be important in evaluating tear film stability alterations occurring in those diseases in which non-goblet epithelial cell vesicles increase.  相似文献   
945.
946.
For monitoring the changes in intracellular free Ca2+ concentration ([Ca2+]i), we developed a simple system combining a fluorescence microscope, an image intensifier, a video-camera, a cathode ray tube display and a photodiode, employing quin2 as a Ca2+ indicator. We recorded increases of the fluorescence intensity due to [Ca2+]i rises, when high K+ medium, neurotransmitter and Ca2+ ionophore were applied to the single cells of nervous system origin in culture. The present system is capable of simultaneous detection of the [Ca2+]i changes from multiple separate cells.  相似文献   
947.
Apart from cannabis abuse in northern and southern Africa and khat chewing in north-eastern Africa, the history of drug abuse in Africa is relatively short. The abuse of drugs in Africa is nevertheless escalating rapidly from cannabis abuse to the more dangerous drugs and from limited groups of drug users to a wider range of people abusing drugs. The most common and available drug of abuse is still cannabis, which is known to be a contributing factor to the occurrence of a schizophrenic-like psychosis. The trafficking in and abuse of cocaine and heroin are the most recent developments in some African countries that had had no previous experience with these drugs. Efforts should be made to design and implement drug abuse assessment programmes to determine the real magnitude and characteristics of the problem and to monitor its trends. A lack of funds and a shortage of adequately trained personnel have made it difficult to implement drug abuse control programmes. In addition to formal drug control involving the implementation of legislation, there is an informal system of drug abuse control operating through the family, church, school, neighbourhood and work environment, as well as healthy recreational activities. It is suggested that efforts in African countries should be directed towards strengthening not only the formal drug control system but also informal control in order to compensate for the insufficient funds and the shortage of personnel trained in implementing formal drug control measures. It is very likely that the drug problems in African countries will worsen in future unless more effective measures are implemented to arrest the current situation.  相似文献   
948.
949.
The production of progesterone from pregnenolone, of cortisol from cortisone and of prostaglandin E (PGE) under basal and arachidonic acid-stimulated conditions was measured in cells dispersed from chorion and decidua. The cells were obtained after delivery from four groups of women: following spontaneous labour at term (38-42 weeks gestation), at elective caesarean section at term before the onset of labour, after induced labour at term, and after uncomplicated preterm (27-36 weeks) labour. Chorionic cells had a high progesterone output with relatively low cortisol and PGE production, whereas decidual cells had a high cortisol and PGE production rate. Free arachidonic acid stimulated PGE production in both decidual and chorionic cells. There were no significant differences in either steroid or PGE production among the four groups studied. These data suggest that steroid dehydrogenase activity in choriodecidual cells is not related to the mode of onset of labour and that the increased prostaglandin production in intrauterine tissues associated with parturition is due to enhanced availability of arachidonic acid.  相似文献   
950.
Placement of the nasojejunal feeding tube under direct visual guidance using endoscopy offers an alternative method to those currently used. We found it to be a safe method easily performed by house staff. It is less burdensome than other described endoscopic techniques and does not require patient transfer or fluoroscopic facilities.  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