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   378917篇
  免费   24162篇
  国内免费   2809篇
耳鼻咽喉   5186篇
儿科学   8205篇
妇产科学   10076篇
基础医学   53087篇
口腔科学   11776篇
临床医学   30082篇
内科学   78244篇
皮肤病学   8546篇
神经病学   27192篇
特种医学   13917篇
外国民族医学   82篇
外科学   60556篇
综合类   9953篇
现状与发展   1篇
一般理论   64篇
预防医学   17423篇
眼科学   9440篇
药学   30972篇
  1篇
中国医学   2193篇
肿瘤学   28892篇
  2021年   2606篇
  2019年   2724篇
  2018年   4514篇
  2017年   3431篇
  2016年   3519篇
  2015年   4016篇
  2014年   5691篇
  2013年   7375篇
  2012年   10014篇
  2011年   10195篇
  2010年   6186篇
  2009年   5834篇
  2008年   9439篇
  2007年   10275篇
  2006年   10194篇
  2005年   9257篇
  2004年   8773篇
  2003年   8507篇
  2002年   8179篇
  2001年   28242篇
  2000年   28770篇
  1999年   23647篇
  1998年   5159篇
  1997年   4248篇
  1996年   3828篇
  1995年   3477篇
  1994年   3103篇
  1993年   2841篇
  1992年   16046篇
  1991年   14809篇
  1990年   14154篇
  1989年   13958篇
  1988年   12579篇
  1987年   12060篇
  1986年   11101篇
  1985年   10320篇
  1984年   6911篇
  1983年   5599篇
  1982年   2718篇
  1979年   5477篇
  1978年   3347篇
  1977年   2971篇
  1975年   2641篇
  1974年   3065篇
  1973年   2867篇
  1972年   2829篇
  1971年   2773篇
  1970年   2511篇
  1969年   2543篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Correction of cryptotia using a subcutaneous pedicled flap   总被引:1,自引:0,他引:1  
Cryptotia is a relatively common deformity of the ear among orientals. Although many methods for correcting this deformity have been reported, there is no one perfect method. We have developed a method using a subcutaneous pedicle flap raised from the retroauricular region, where relative abundance of skin exists. We have treated 9 ears of 7 patients by the method reported herein. Results are satisfactory in all cases.  相似文献   
992.
993.
The usefulness of an ultrasonic duplex system to assess portal blood flow was investigated. In a model involving a steady flow through a vinyl tube in agar, there was a significant linear correlation between the maximum blood flow velocity measured by this system (V-max) and the mean blood flow velocity calculated from the actually measured blood flow volume (V-mean), that is, V-mean = 0.53 X V-max was obtained (r = 0.994; n = 47). This equation was used to calculate the mean portal blood flow velocity by this system (V-dopp) in 10 patients with liver disease, and the findings were compared with data simultaneously obtained by cineangiographic mapping of Lipiodol droplets released into the portal vein through a catheter placed in situ at the time of surgery (V-cine). A linear correlation between V-dopp and V-cine was statistically significant (r = 0.970; n = 13), and the regression line was V-cine = 1.29 X V-dopp -2.11. The ultrasonic duplex system proved reliable for a quantitative assessment of portal hemodynamics.  相似文献   
994.
995.
996.
997.
998.
Effects of stimulation of brainstem sites on hemodynamics and plasma catecholamine levels were assessed in cats under chloralose-urethane anesthesia. Pressor areas of the dorsal medulla (DM) and ventrolateral medulla (VLM) and the depressor area of the paramedian reticular nucleus (PRN) were stimulated electrically using a monopolar electrode, or chemically using sodium glutamate microinjection. Plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured in caval blood above the adrenal veins. Electrical stimulation of the DM and VLM produced increases in blood pressure and in plasma NE and EPI levels that were enhanced after acute vagotomies. The NE and EPI responses were attenuated after acute, bilateral adrenalectomies, confirming augmented adrenomedullary secretion, whereas the pressor responses were intact. Injection of sodium glutamate into the same pressor regions of the DM or VLM also produced pressor responses and elevated plasma catecholamine levels, indicating that the responses resulted from activation of neuronal perikarya. Stimulation of the PRN attenuated pressor and catecholamine responses during stimulation of the DM and VLM. The results indicate that pressor responses during stimulation of the DM and VLM are due at least partly to activation of perikarya in these regions, are associated with but not dependent on adrenomedullary activation, and are enhanced after vagotomy; and that neurons of the PRN exert inhibitory modulation of the pressor and adrenomedullary responses during stimulation of VLM and DM.  相似文献   
999.
The behavioral pharmacological effects of Ca-4-(3,5-dihydroxy-3-methylpenthylamido) butyrate (mevalonic-GABA, MV-GABA), a new GABA derivative were studied in comparison with those of Ca-hopantenate (HOPA) in mice. MV-GABA had no effect on the general behavior and electric shock-induced fighting behavior. The dosage of MV-GABA which caused locomotor hypoactivity produced an impairment of the rotarod performance. MV-GABA inhibited the hyperactivity induced by a dopamine (DA) agonist (methamphetamine) and acetylcholine (ACh) antagonists (scopolamine and atropine) at a dose which did not affect locomotor activity in normal mice. MV-GABA prolonged the pentobarbital-Na-induced sleeping time, and it prolonged the latencies until convulsion and death after administration of strychnine. MV-GABA and HOPA antagonized the electroconvulsive shock-induced amnesia in the passive avoidance response of mice. These results suggest that MV-GABA has effects on the central nervous systems, in particular, ACh and DA neural systems. The actions of MV-GABA were qualitatively similar to those of HOPA except for the effect on the DA neural system.  相似文献   
1000.
The effect of testosterone and anabolic steroids on the size of sebaceous glands was studied by means of interactive morphometry in skin biopsies of power athletes. The subjects used self-administered high doses of testosterone and anabolic steroids during a 4-week strength training period. After 4 weeks' use of hormones, the area of sectioned sebaceous glands enlarged significantly by a factor of 89.2% (p less than 0.005). The number of cells in the so-called differentiating cell pool (DCP) and in the undifferentiated cell pool (UCP) also increased significantly (p less than 0.025, p less than 0.05, respectively). The size of the area occupied by UCP cells increased significantly (p less than 0.05). The study suggests that high doses of testosterone and anabolic steroids lead to an enlargement of sebaceous glands in male power athletes.  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