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   3123084篇
  免费   237245篇
  国内免费   5225篇
耳鼻咽喉   45472篇
儿科学   98214篇
妇产科学   82905篇
基础医学   439300篇
口腔科学   89838篇
临床医学   282925篇
内科学   602996篇
皮肤病学   65740篇
神经病学   255414篇
特种医学   124182篇
外国民族医学   1082篇
外科学   472485篇
综合类   72014篇
现状与发展   2篇
一般理论   1201篇
预防医学   244197篇
眼科学   73927篇
药学   238045篇
  11篇
中国医学   6379篇
肿瘤学   169225篇
  2018年   31880篇
  2017年   24663篇
  2016年   27378篇
  2015年   30801篇
  2014年   43934篇
  2013年   66234篇
  2012年   89815篇
  2011年   94839篇
  2010年   56000篇
  2009年   53271篇
  2008年   89427篇
  2007年   95552篇
  2006年   96827篇
  2005年   93651篇
  2004年   90204篇
  2003年   86978篇
  2002年   85523篇
  2001年   149141篇
  2000年   154459篇
  1999年   130337篇
  1998年   36448篇
  1997年   32830篇
  1996年   32609篇
  1995年   31255篇
  1994年   29217篇
  1993年   27311篇
  1992年   103999篇
  1991年   100293篇
  1990年   97180篇
  1989年   93855篇
  1988年   86820篇
  1987年   85142篇
  1986年   80761篇
  1985年   76914篇
  1984年   57558篇
  1983年   48916篇
  1982年   29014篇
  1981年   25640篇
  1979年   53579篇
  1978年   37181篇
  1977年   31968篇
  1976年   29333篇
  1975年   31603篇
  1974年   38482篇
  1973年   36609篇
  1972年   34464篇
  1971年   32020篇
  1970年   30066篇
  1969年   28212篇
  1968年   25511篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The potential antidepressant effect of flerobuterol (dl-(fluoro-2 phenyl)-1 t-butylamino-2 ethanol), a new drug related to beta-adrenoceptor agonists, was evaluated and compared with imipramine and salbutamol using classical psychopharmacological tests in mice. Like imipramine and salbutamol, flerobuterol (0.5-32 mg kg-1, ip) fully prevented apomorphine (16 mg kg-1, sc)- and partly reversed reserpine- and oxotremorine-induced hypothermia. At higher doses (16-32 mg kg-1), flerobuterol enhanced the toxic effects of yohimbine. Unlike imipramine, flerobuterol and salbutamol did not reduce immobility duration in the behavioural despair test. Salbutamol and flerobuterol decreased locomotor activity. Flerobuterol did not induce mydriasis, did not prevent oxotremorine-induced tremors or salivary and lacrimal gland secretion and did not reduce reserpine-induced palpebral ptosis. Propranolol (8 mg kg-1, ip) but not alpha-methyl-paratyrosine (75 mg kg-1, ip) prevented the flerobuterol-induced antagonism of apomorphine-induced hypothermia. Our results suggest that flerobuterol demonstrates potential antidepressant activity, which could be related to beta-adrenoceptor activation in mice.  相似文献   
992.
When human divers and experimental animals are exposed to an increasing environmental pressure, they develop the high pressure neurological syndrome (HPNS) characterized by electroencephalographic changes and sleep and behavioral disturbances. In rats, behavioral disturbances essentially include hyperlocomotor activity (HLA), tremor and myoclonia. Moreover, HLA has recently been demonstrated to be linked to a pressure-induced striatal increase of dopamine (DA). In these experiments, it was proposed to investigate in rats, at the behavioral level, the role of DA receptors in the occurrence of the pressure-induced DA disturbances. DA receptor agonists were found to induce no significant changes in the development of HLA, tremor, and myoclonia. Alternatively, HLA was found to be dramatically antagonized by the use of DA receptor antagonists (SCH 23390, sulpiride, and haloperidol), while tremor and myoclonia only decreased in SCH 23390 experiments.  相似文献   
993.
994.
A review of lacrimal drainage surgery   总被引:3,自引:0,他引:3  
The advent of improved silicone intubation sets, increased understanding of lacrimal and nasal anatomy and physiology, and refinements in surgical instrumentation and technique have led to higher success rates in lacrimal surgery. Recent clinical studies, combined with new techniques in canalicular reconstruction, have helped identify which patients will benefit from surgical intervention and which techniques are indicated. Fortunately, this has greatly reduced the number of CDCRs necessary.  相似文献   
995.
In the operative treatment of appendicitis the so called negative appendectomy is an important issue because of its increased morbidity. From the hypothesis that the intestinal diamine oxidase activity is a suitable marker of mucosal integrity, the distribution pattern of the enzyme in appendices histologically classified as inflamed or not inflamed was studied. Histologically apparent inflammation of the appendix was connected with a significant reduction of diamine oxidase activity. The determination of this enzymic activity may be a simple and sensitive test for mucosal inflammation of the appendix even at a very early state. This could reduce the rate of negative appendectomies and influence thereby risk-cost-benefit calculations.  相似文献   
996.
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   
997.
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   
998.
A brief historical review of the role of female medical students and female physicians in American medicine is presented. The 1985-1986 Council on Resident Education in Obstetrics and Gynecology Residency Data Bank was analyzed for gender distribution. Questionnaire studies were undertaken to study the possible effect of the increasing number of female residents in an obstetrics and gynecology residency program. Queries were sent to current and former residents, the attending staff, and the nursing and anesthesiology staffs. In order to evaluate the national scene, letters were mailed to directors of programs with 20 or more residents. The overall results indicated female residents have a positive effect on residency training.  相似文献   
999.
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   
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