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   26245篇
  免费   1230篇
  国内免费   107篇
耳鼻咽喉   285篇
儿科学   495篇
妇产科学   325篇
基础医学   3508篇
口腔科学   666篇
临床医学   1791篇
内科学   6741篇
皮肤病学   389篇
神经病学   2087篇
特种医学   1095篇
外科学   4223篇
综合类   110篇
一般理论   2篇
预防医学   639篇
眼科学   489篇
药学   1821篇
中国医学   99篇
肿瘤学   2817篇
  2023年   128篇
  2022年   251篇
  2021年   378篇
  2020年   179篇
  2019年   309篇
  2018年   399篇
  2017年   341篇
  2016年   411篇
  2015年   440篇
  2014年   589篇
  2013年   728篇
  2012年   1218篇
  2011年   1357篇
  2010年   760篇
  2009年   708篇
  2008年   1200篇
  2007年   1325篇
  2006年   1278篇
  2005年   1344篇
  2004年   1308篇
  2003年   1238篇
  2002年   1240篇
  2001年   762篇
  2000年   817篇
  1999年   780篇
  1998年   384篇
  1997年   329篇
  1996年   341篇
  1995年   264篇
  1994年   279篇
  1993年   238篇
  1992年   568篇
  1991年   572篇
  1990年   536篇
  1989年   502篇
  1988年   406篇
  1987年   366篇
  1986年   399篇
  1985年   360篇
  1984年   270篇
  1983年   232篇
  1982年   138篇
  1981年   127篇
  1980年   127篇
  1979年   194篇
  1978年   142篇
  1977年   123篇
  1974年   116篇
  1972年   116篇
  1968年   104篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
In order to treat fistulated esophageal cancer using a flexible stent, a covered flexible stent was constructed by wrapping a nitinol stent with a thin sheet of Gore-Tex, preserving the stents original advantages of flexibility and a low-profile introducer system. This stent was used to perform standard radiotherapy in a case of fistulated esophageal cancer.  相似文献   
32.
33.
Autosomal dominant neovascular inflammatory vitreoretinopathy   总被引:1,自引:0,他引:1  
S R Bennett  J C Folk  A E Kimura  S R Russell  E M Stone  E M Raphtis 《Ophthalmology》1990,97(9):1125-35; discussion 1135-6
Twenty-eight of 61 members of a six-generation family are affected by an autosomal dominant eye disease which has not been described previously. Affected patients are asymptomatic in early adulthood, but have vitreous cells and the selective loss of the b-wave on the electroretinogram. Later, peripheral retinal scarring and pigmentation, peripheral arteriolar closure, and neovascularization of the peripheral retina at the ora serrata or occasionally neovascularization of the optic disc develop. Cystoid macular edema, vitreous hemorrhage, tractional retinal detachment, and neovascular glaucoma can cause profound visual loss. Vitrectomy reduces traction on the retina and allows for retinal reattachment. The role of argon laser photocoagulation or cryopexy in reducing the neovascular complications remains uncertain.  相似文献   
34.
Acetylcholinesterase activity and pseudocholinesterase activity were examined in plasma and in striated muscles (whole heart and diaphragm muscles) of diabetic KK-CAy mice. Both activities of acetylcholinesterase in heart muscle and pseudocholinesterase in plasma were significantly increased in diabetic KK-CAy mice compared to pre-diabetic KK-CAy mice. Both acetylcholinesterase and pseudocholinesterase activities in skeletal muscle were not changed by the diabetic state. The increases in activity of plasma pseudocholinesterase was significantly correlated to the increase in blood glucose level in alloxan-, streptozotocin (STZ)-diabetic ddY mice and diabetic KK-CAy mice. The increase was not correlated to the body weight in non-diabetic female-KK-CAy mice. Furthermore, the activity of heart acetylcholinesterase was significantly correlated with the activity of plasma pseudocholinesterase (r = 0.79, P less than 0.01). The activities of acetylcholinesterases in heart muscles from STZ- and alloxan-diabetic ddY mice also tended to increase. The hypersensitivity of the pulse rate to a low dose (1 mg/kg) of acetylcholine was correlated to the activity of plasma pseudocholinesterase (r = -0.51, P less than 0.05). These results demonstrate that the activities of plasma pseudocholinesterase were increased by the diabetic state being associated with the increasing alteration of cardiac sensitivity to acetylcholine in the whole body.  相似文献   
35.
36.
The effect of (+)-5-oxo-D-prolinepiperidinamide monohydrate (NS-105), a novel cognition enhancer, on adenylate cyclase activity was investigated in cultured neurons of the mouse cerebral cortex. NS-105 (10–7 and 10–6 M) inhibited forskolin-stimulated cyclic AMP formation, an action that was dependent on pertussis toxin-sensitive G proteins. Conversely, in pertussis toxin-pretreated neurons, NS-105 (10–7 –10–5 M) significantly enhanced the forskolin-stimulated cyclic AMP formation, and this action was completely reversed by cholera toxin. A metabotropic glutamate receptor agonist (1S, 3R)-1-aminocyclopentane-1, 3-dicarboxylic acid (1S, 3R-ACPD) produced similar bi-directional actions on the cyclic AMP formation. Both of these inhibitory and facilitatory actions of NS-105 and 1S, 3R-ACPD were blocked by L(+)-2-amino-3-phosphopropinoic acid (L-AP3). NS-105 (10–6 M) and 1S, 3R-ACPD (10–4 M) significantly enhanced isoproterenol- and adenosine-stimulated cyclic AMP formation. The enhancement of such Gs-coupled receptor agonists-stimulated cyclic AMP formation was also produced by quisqualate but not by L(+)-2-amino-4-phosphonobutanoate (L-AP4). The phosphoinositides hydrolysis was enhanced by 1S, 3R-ACPD (10–4 M) but not by NS-105 (10–6 M), however, 1S, 3R-ACPD-induced increase in phosphoinositides turnover was attenuated by NS-105. These findings suggest that NS-105 stimulates metabotropic glutamate receptor subclasses that are coupled both negatively and positively to adenylate cyclase, but it acts as an antagonist at the receptor subclasses that are linked to phosphoinositides hydrolysis. Received: 3 February 1997 / Accepted: 25 April 1997  相似文献   
37.
We studied subsets and cytotoxicity of recombinant interleukin-2 (rIL-2) expanded tumor infiltrating lymphocytes (TIL) from renal cell cancer (RCC) patients. TIL were successfully expanded in 13 of 14 RCC cases using anti-CD3 during initial 48 hours of culture. Percentages of CD8 positive cells among rIL-2 expanded TIL at 1 tp 4 week(s) of culture were 56.2 +/- 15.1% (range 26.2 to 79.8%, N = 13) and not necessarily predominant over CD4 positive cells. NK and LAK activities of TIL at 3 to 6 weeks of culture were 31.6 +/- 15.8% (range 1.4 to 57.4%, N = 9) and 16.6 +/- 11.6% (range 3.8 to 35.6%, N = 6), respectively. Autologous and allogeneic RCC cytotoxicity of TIL at 3 to 4 weeks of culture were 17.9 +/- 19.7% (range 0 to 47.6%, N = 4) and 18.9 +/- 14.8% (range 0 to 47.3%, N = 12), respectively. Since there was no statistical difference between them, autologous specific cytotoxicity was not demonstrated. From these results of present study, it is unlikely that most of effector cells of rIL-2 expanded TIL in autologous RCC lysis are major histocompatibility complex restricted cytotoxic T cells. And we concluded that it is doubtful that TIL is significantly superior over LAK cells in immunotherapy of human RCC.  相似文献   
38.
It has been well documented that piriform sinus fistulae often cause suppurative thyroditis; however, when a piriform sinus fistula does not present this symptom, making a correct diagnosis is very difficult. We have experienced 11 cases of a piriform sinus fistula. The conventional operational approach was performed in the initial eight patients, among which there were four recurrences in two patients. Therefore, a new operational approach was introduced for the three most recent cases and one recurrent case. First, the existence of the internal orifice of the fistula is confirmed with a laryngoscope, after which a transverse incision on the neck is made and the abscess dissected. The side wall of the piriform sinus is then opened with the help of a laryngoscope and the bottom part of the mucosa of the sinus transected with the internal orifice of the fistula, after which the fistula is removed en bloc with the bottom part of the sinus and abscess cavity. Using this operation, we experienced no complications and there has been no recurrence so far.This paper was presented at the 23rd Annual Meeting of Pacific Association of Pediatric Surgeons, June 1990 in Kona, Hawaii.  相似文献   
39.
We successfully replanted five amputated legs in five patients and followed the patients for two years or more (average, six years and three months). Although some patients found it impossible to squat and to run because of joint contractures, muscle weakness, or deformities of the foot, all patients could perform other activities without difficulty. None had important pain or any intolerance to cold, and all were satisfied with the results of the replantation.  相似文献   
40.
Carbon fibers with fibrin glue were used as electrodes for diaphragm pacing. The electrodes were applied to three mongrel dogs and the effectiveness was tested. The carbon leads were glued to phrenic nerves by means of the fibrinogen and thrombin bilaterally. The tidal volumes and threshold current level for stimulation were measured at various time up to 9 weeks after implantation. Effective contraction of diaphragm were observed for 9 weeks. By using this electrode, the exfoliation of the nerve is not necessary, the nerve can be maintained in an intact state, and the risk of the implanting operation can be minimized.  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