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   1857231篇
  免费   127572篇
  国内免费   3781篇
耳鼻咽喉   22861篇
儿科学   61705篇
妇产科学   49027篇
基础医学   256756篇
口腔科学   50212篇
临床医学   163069篇
内科学   362211篇
皮肤病学   39314篇
神经病学   146647篇
特种医学   72265篇
外国民族医学   242篇
外科学   284301篇
综合类   41204篇
现状与发展   4篇
一般理论   542篇
预防医学   141206篇
眼科学   42897篇
药学   132640篇
  7篇
中国医学   5101篇
肿瘤学   116373篇
  2021年   13015篇
  2019年   13707篇
  2018年   40216篇
  2017年   31153篇
  2016年   34522篇
  2015年   19945篇
  2014年   27119篇
  2013年   38910篇
  2012年   59460篇
  2011年   75104篇
  2010年   50136篇
  2009年   41437篇
  2008年   69728篇
  2007年   75004篇
  2006年   55961篇
  2005年   54732篇
  2004年   54066篇
  2003年   52292篇
  2002年   48774篇
  2001年   92038篇
  2000年   93988篇
  1999年   77106篇
  1998年   19927篇
  1997年   17460篇
  1996年   17461篇
  1995年   16839篇
  1994年   15385篇
  1993年   14130篇
  1992年   57416篇
  1991年   55343篇
  1990年   53086篇
  1989年   50820篇
  1988年   46184篇
  1987年   44975篇
  1986年   42246篇
  1985年   40018篇
  1984年   29373篇
  1983年   24935篇
  1982年   13922篇
  1979年   25543篇
  1978年   17591篇
  1977年   14912篇
  1976年   13887篇
  1975年   14571篇
  1974年   17653篇
  1973年   16949篇
  1972年   15677篇
  1971年   14454篇
  1970年   13449篇
  1969年   12536篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
991.
There is increasing evidence from human and experimental studies that the most important factor governing the outcome in head injury is the severity of diffuse axonal injuries. The authors have experienced 18 cases of severe diffuse axonal injury which showed post-traumatic coma for more than 24 hours and CT findings resembling those of shearing injuries of the cerebral white matter such as have been presented by Zimmerman et al. (1978). The consciousness levels on admission were 6 or less on the Glasgow Coma Scale and all cases were shown clinically to have primary brain stem injury. The main type of head trauma resulted from road traffic accidents (83%). Skull fractures were found in only 5 cases (28%). These findings suggested that acceleration/deceleration injury produce in the patients severe diffuse axonal injury. Initial ICP was below 20 mmHg in 11 cases out of 13 (85%). Parenchymal small hemorrhagic lesions of initial CT were basal ganglia (7 cases), corpus callosum (4 cases), pons (4 cases), midbrain (3 cases) and thalamus (2 cases). Extraparenchymal hemorrhagic lesions included intraventricular hemorrhage (6 cases) and subarachnoid hemorrhage (6 cases). Two autopsied cases of severe diffuse axonal injury (acute case and chronic case) showed remarkable congestion and edema in the deep part of the frontal white matter. Microscopic examination revealed marked axonal degeneration including axonal retraction ball in the corpus callosum, in the internal capsule and in the white matter of the brain stem. Glasgow Outcome Scale of the 18 patients at 3 months after the trauma made us concerned that no patients indicated good recovery or even only moderate disability.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
992.
A series of C(3)-cyclopropyl cephems and carbacephems has been prepared by palladium catalyzed addition of diazomethane to the corresponding C(3)-vinyl derivatives. The phenylglycyl cyclopropyl cephem derivatives exhibit better Gram-positive activity than cephalexin or cefaclor, while the aminothiazole oxime cyclopropyl cephem derivatives were not as active as the corresponding C(3)-vinyl cephems.  相似文献   
993.
The hepatotropic effect of nonsteroidal anti-inflammatory drugs (NSAID) such as indomethacin, voltaren, piroxicam, phenylbutazon, mefenamic acid was studied. It was found that according to their level of the pharmacological protection of the liver against tetrachlormethan these agents may be arranged in the following sequence: mefenamic acid, phenylbutazon, voltaren, piroxicam. The hepatoprotective effect of NSAID correlates with the antioxidant properties and fails to correlate with the antioxidant ones. The hepatotoxic effect of NSAID was determined by their ability to suppress synthesis of prostaglandins.  相似文献   
994.
The effect of oxitropium bromide (Ba253), a quaternary scopolamine derivative, on the resting tonus and agonist-induced contraction of isolated guinea pig airway smooth muscle and on the anaphylactic release of histamine and immunoreactive leukotrienes (i-LTs) from lung fragments were investigated and compared with those of Sch1000, atropine and isoproterenol. Ba253 dose-dependently inhibited the acetylcholine (ACh)-induced contraction of the isolated trachea and lung parenchyma. The degree of inhibitory potency was similar to that of Sch1000 and 10 times higher than that of atropine. Ba253 minimally influenced the resting tonus or contractions induced by other agonists including histamine, serotonin and LTD4. Sch1000 and atropine had similar or slightly stronger inhibitory effects on the tonus and contractions than Ba253. On the other hand, low concentrations of isoproterenol solely relaxed the resting tonus and inhibited the the agonist-induced contractions of both preparations. Neither Ba253 nor Sch1000 inhibited the anaphylactic release of histamine and LTs from both guinea pig and human lung fragments, but both mediator releases from either species were slightly inhibited with dose-dependency by atropine and potently inhibited by isoproterenol. From these results, it is suggested that Ba253 is a relatively specific antagonist to cholinergic receptors and might be possibly effective as an inhalant for asthma.  相似文献   
995.
996.
Three cases of voluntary posterior instability of the shoulder are presented. They have all responded well to a program of electromyographic monitored biofeedback. This method offers a means of enhancing the results of nonoperative treatment.  相似文献   
997.
998.
999.
Spinal antinociceptive effects of adenosine compounds in mice   总被引:1,自引:0,他引:1  
The effects of injecting ATP, ADP, AMP, adenosine and adenine intrathecally on the pain response induced by the injection of substance P (10 ng/mouse) intrathecally were studied. All the compounds except adenine inhibited the pain response in a dose-related manner. The ED50 values of ATP, ADP, AMP and adenosine were 2.10, 0.93, 0.88 and 0.48 micrograms/mouse, respectively. Pretreatment with theophylline at a dose of 100 mg/kg p.o. markedly diminished all the antinociceptive effects. The effect of adenosine was not affected by s.c. injection of naloxone. These results suggest the existence of adenosine receptors which modulate spinal nociceptive sensory processing, independently of the endogenous opiate system.  相似文献   
1000.
Reported in this paper are postoperative results recorded from 120 patients, 3 years after selective proximal vagotomy for uncomplicated duodenal ulcer. There was no intraoperative lethality and no recurrence in 96.7 per cent of all cases, while Visick grades I on II were recorded from 98.2 per cent. Radiologically and gastroscopically detected pathological processes receded soon. Average postoperative reduction in acid secretion was 66.2 per cent in BAO and 46.8 per cent in MAO. Acid values re-increased thereafter, and three years later reduction rates still amounted to 43.7 per cent in BAO and 28.6 per cent in MAO. Indications for proximal gastric vagotomy are discussed in some detail.  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