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   2601439篇
  免费   200761篇
  国内免费   6349篇
耳鼻咽喉   34879篇
儿科学   86240篇
妇产科学   73062篇
基础医学   375352篇
口腔科学   74931篇
临床医学   241611篇
内科学   500429篇
皮肤病学   54315篇
神经病学   213661篇
特种医学   99221篇
外国民族医学   804篇
外科学   378248篇
综合类   62374篇
现状与发展   4篇
一般理论   958篇
预防医学   212837篇
眼科学   59373篇
药学   194606篇
  9篇
中国医学   5427篇
肿瘤学   140208篇
  2018年   27440篇
  2017年   21052篇
  2016年   23228篇
  2015年   26697篇
  2014年   36787篇
  2013年   56826篇
  2012年   77330篇
  2011年   81961篇
  2010年   48100篇
  2009年   45126篇
  2008年   76671篇
  2007年   80971篇
  2006年   81589篇
  2005年   79188篇
  2004年   76796篇
  2003年   73267篇
  2002年   71587篇
  2001年   117045篇
  2000年   120936篇
  1999年   102086篇
  1998年   28877篇
  1997年   26246篇
  1996年   25976篇
  1995年   25104篇
  1994年   23579篇
  1993年   22269篇
  1992年   83444篇
  1991年   81652篇
  1990年   79469篇
  1989年   76327篇
  1988年   70996篇
  1987年   69661篇
  1986年   66441篇
  1985年   63974篇
  1984年   48115篇
  1983年   41314篇
  1982年   24708篇
  1981年   21997篇
  1979年   45148篇
  1978年   31736篇
  1977年   26552篇
  1976年   25355篇
  1975年   26591篇
  1974年   32482篇
  1973年   31454篇
  1972年   28943篇
  1971年   27179篇
  1970年   25055篇
  1969年   23264篇
  1968年   21759篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
952.
A total of 42 patients with recurrent superficial bladder tumors or carcinoma in situ entered a prospective, randomized trial to compare the efficacy of bacillus Calmette-Guerin therapy with and without quarterly maintenance instillations of bacillus Calmette-Guerin. Maintenance therapy did not reduce further bladder tumor recurrence rates or the interval to recurrence in patients who responded to the initial course of therapy. However, prolongation of toxicity was observed with maintenance bacillus Calmette-Guerin therapy.  相似文献   
953.
954.
Kojic amine [2-(aminomethyl)-5-hydroxy-4H-pyran-4-one], an analogue of gamma-aminobutyric acid (GABA), produced dose-related, but short-lived, antinociceptive activity in the 48 degrees C [ED50 = 9.2 (8.2-10.3) mg/kg i.p.] and 55 degrees C [ED50 = 13.8 (12.2-15.7) mg/kg i.p.] hot-plate tests in the mouse. The antinociceptive activity of kojic amine at 48 degrees C was found to be insensitive to bicuculline (1.0 mg/kg i.p.) and picrotoxin (0.5 mg/kg i.p.). At this temperature, antinociception was distinctly separate from the impairment of motor function (measured by a rotorod assay) and was not significantly affected by prior treatment with the cholinergic antagonist, atropine sulfate (10.0 mg/kg i.p.). However, at 55 degrees C, the antinociceptive effect of a large dose (20 mg/kg i.p.) of kojic amine was significantly attenuated by similar pretreatment with atropine sulfate, but not by the peripheral cholinergic antagonist, atropine methylnitrate (10.0 mg/kg i.p.). Kojic amine exhibited no significant interaction with haloperidol (0.5 mg/kg i.p.) at this temperature. In animals made tolerant to morphine, THIP or baclofen, there was analgesic cross-tolerance between kojic amine, morphine and baclofen but not between kojic amine and THIP. It is suggested that kojic amine-induced antinociception is similar to that produced by both THIP and baclofen. Thus, kojic amine represents a unique tool with which to study GABA-ergic antinociceptive processes.  相似文献   
955.
Computed tomography of the brain in the Smith-Lemli-Opitz syndrome   总被引:1,自引:0,他引:1  
Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome.  相似文献   
956.
Intracranial venous thrombosis has been described in newborns, but there have been no reports of intractable neonatal seizures due to this condition. We report cortical venous sinus thrombosis in two term neonates who presented with seizures in the first 24 hours of life. The diagnosis was made by cranial computed tomography and was confirmed by cerebral angiography. Both patients improved clinically after the intracranial venous thrombosis resolved. These patients demonstrate that intracranial venous thrombosis should be considered in the differential diagnosis of neonatal seizures.  相似文献   
957.
958.
We compared the biomechanical properties of passive and stimulated muscle rapidly lengthened to failure in an experimental animal model. The mechanical parameters compared were force to tear, change in length to tear, site of failure, and energy absorbed by the muscle-tendon unit before failure. Paired comparisons were made between 1) muscles stimulated at 64 Hz (tetanic stimulation) and passive (no stimulation) muscles, 2) muscles stimulated at 16 Hz (wave-summated stimulation) and passive muscles, and 3) muscles stimulated at 64 Hz and at 16 Hz. Both tetanically stimulated and wave-summation contracted muscles required a greater force to tear (at 64 Hz, 12.86 N more, P less than 0.0004; and at 16 Hz, 17.79 N more, P less than 0.003) than their nonstimulated controls, while there was no statistical difference in failure force between muscles stimulated at 16 Hz and 64 Hz. The energy absorbed was statistically greater for the stimulated muscles than for the passive muscles in Groups 1 and 2 (at 64 Hz, 100% more, P less than 0.0003; and 16 Hz, 88% more, P less than 0.0002). In Group 3, the tetanically contracted muscle-tendon units absorbed 18% more energy than the wave-summated stimulated muscles (P less than 0.01). All muscles tore at the distal musculotendinous junction, and there was no difference in the length increase at tear between muscles in each group. These findings may lead to enhanced understanding of the mechanism and physiology of muscle strain injuries.  相似文献   
959.
960.
Beta-blockers are among the most widely used antihypertensive drugs. They differ from each other in regard to several factors such as: beta-agonist activity, beta 1-selectivity and solubility. Aim of this work was to evaluate the influence of obesity on the kinetics and the antihypertensive effect of two Beta-blockers with different solubility such as: the water-soluble, atenolol and the liposoluble, metoprolol. The study was carried out according to an open randomized cross-over design. Eight obese hypertensive patients, after a two week washout period, were randomly allocated to a four week treatment. After a two week intermediate washout period, each patient switched to the other treatment for an additional four week period. On the first and the last day of each treatment the subjects were hospitalized to collect blood samples for the assay of the two drugs and to measure cardiovascular parameters. Obesity does not exert any effect on the kinetics of the water-soluble beta-blocker, atenolol, while markedly interferes with that of the liposoluble, without any apparent influence on its anti-hypertensive effect. These findings extend to obese hypertensives the concept that the plasma concentrations of beta-blocking agents are not reliable predictors of their therapeutic effect.  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