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   3221篇
  免费   225篇
  国内免费   116篇
耳鼻咽喉   24篇
儿科学   88篇
妇产科学   38篇
基础医学   392篇
口腔科学   101篇
临床医学   353篇
内科学   655篇
皮肤病学   108篇
神经病学   214篇
特种医学   401篇
外国民族医学   1篇
外科学   340篇
综合类   110篇
一般理论   1篇
预防医学   189篇
眼科学   146篇
药学   181篇
中国医学   4篇
肿瘤学   216篇
  2023年   21篇
  2022年   28篇
  2021年   92篇
  2020年   75篇
  2019年   69篇
  2018年   88篇
  2017年   46篇
  2016年   79篇
  2015年   95篇
  2014年   109篇
  2013年   161篇
  2012年   159篇
  2011年   155篇
  2010年   112篇
  2009年   119篇
  2008年   134篇
  2007年   165篇
  2006年   133篇
  2005年   152篇
  2004年   95篇
  2003年   67篇
  2002年   69篇
  2001年   53篇
  2000年   58篇
  1999年   64篇
  1998年   111篇
  1997年   105篇
  1996年   117篇
  1995年   76篇
  1994年   66篇
  1993年   66篇
  1992年   26篇
  1991年   39篇
  1990年   40篇
  1989年   68篇
  1988年   50篇
  1987年   61篇
  1986年   40篇
  1985年   54篇
  1984年   32篇
  1983年   17篇
  1982年   27篇
  1981年   24篇
  1980年   31篇
  1979年   16篇
  1978年   13篇
  1977年   19篇
  1976年   30篇
  1975年   16篇
  1974年   4篇
排序方式: 共有3562条查询结果,搜索用时 0 毫秒
1.
2.
3.
Summary— To investigate if the functional alterations observed in resistance arteries of spontaneously hypertensive rats (SHRs) were also present at the coronary level, in vitro experiments were performed in mesenteric resistance arteries (MRA) and in right (RIC) and left interventricular coronary (LIC) arteries taken from 15–25-week-old SHR and age-matched Wistar Kyoto rats WKYs. Using a passive extension protocol, internal diameters corresponding to 100 mmHg intraluminal pressure (D100) were determined and vessels were set up to a normalized internal diameter (0.9 D100). SHR mesenteric resistance arteries had a significantly smaller diameter compared to WKY arteries, whereas both types of SHR coronary arteries had a greater diameter compared to those of WKY rats. In arteries in the absence of contracting agonist, nitro-L-arginine (NOLA, 100 μM) induced a progressive rise in basal tone, which could be reversed by subsequent addition of L-arginine (100 μM) but not D-arginine (100 μM). When expressed as percent of maximal contractions induced by agonists (noradrenaline, NA [10 μM] in MRA; serotonin, 5-HT [10 μM], in RIC and LIC), these contractions were significantly stronger in WKY compared to SHR coronary and mesenteric resistance arteries. In NA-precontracted MRA and 5HT-precontracted coronary arteries in the presence of indomethacin (10 μM), the magnitude of acetylcholine-induced maximal relaxations (expressed as percent of maximal contractions induced by agonists) was greater in WKY compared to SHR arteries. After a 30-min incubation period, NOLA (100 μM) completely inhibited relaxations induced by acetylcholine (0.01–10 μM) in all types of precontracted arteries. Subsequent additions of sodium nitroprusside, (SNP, 10 μM) induced complete relaxations in all preparations. These results show that a basal release of NO or NO-like compound by endothelial cells is present in isolated mesenteric resistance and coronary arteries of WKY rats and SHRs. The contribution of endothelium-derived relaxing factor-nitric oxide (EDRF-NO) to arterial tone was lower in MRA compared to coronary arteries in both strains and in SHR compared to WKY arteries. In the SHR preparations, the impaired relaxation induced by acetylcholine appeared to be due to a functional alteration of the endothelium in the presence of normal reactivity of the smooth muscle cells.  相似文献   
4.
表小檗碱对α受体的作用   总被引:2,自引:0,他引:2  
王嘉陵  方达超 《药学学报》1990,25(4):289-292
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择  相似文献   
5.
6.
7.
The authors measure the efficacy of three methods for predicting the time to infection for susceptible individuals in a population undergoing an HIV epidemic. The methods differ in whether they require detailed information of the contact network and whether they require knowledge of the initial source of infection. Efficacy is evaluated using simulations for 20 different contact patterns. Only the risk score that uses both kinds of information accounts for more than 15 per cent of individual variability. The efficacy of this score ranges from 10 per cent in very unstructured populations to 60 per cent for spatially localized contact networks. This improved performance may be explained by the larger fraction of the total variability not due to the disease dynamics. When all variables are dichotomized, the two poorer methods produce odds ratios between 1.4 and 2.3. The odds ratio for the risk score with full information ranges from 2.5 to 17. Risk assessment protocols and intervention programmes are encouraged to assess contact patterns and detect sources of infection.  相似文献   
8.
Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs.  相似文献   
9.
10.
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