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   15101篇
  免费   662篇
  国内免费   39篇
耳鼻咽喉   522篇
儿科学   1423篇
妇产科学   536篇
基础医学   954篇
口腔科学   906篇
临床医学   1046篇
内科学   2569篇
皮肤病学   372篇
神经病学   944篇
特种医学   687篇
外科学   3515篇
综合类   136篇
一般理论   7篇
预防医学   425篇
眼科学   521篇
药学   780篇
  1篇
中国医学   59篇
肿瘤学   399篇
  2024年   14篇
  2023年   171篇
  2022年   118篇
  2021年   264篇
  2020年   203篇
  2019年   264篇
  2018年   462篇
  2017年   407篇
  2016年   475篇
  2015年   363篇
  2014年   531篇
  2013年   790篇
  2012年   881篇
  2011年   1024篇
  2010年   571篇
  2009年   351篇
  2008年   906篇
  2007年   944篇
  2006年   965篇
  2005年   961篇
  2004年   975篇
  2003年   927篇
  2002年   907篇
  2001年   537篇
  2000年   584篇
  1999年   401篇
  1998年   115篇
  1997年   105篇
  1996年   90篇
  1995年   51篇
  1994年   46篇
  1993年   25篇
  1992年   31篇
  1991年   33篇
  1990年   34篇
  1989年   31篇
  1988年   19篇
  1987年   17篇
  1986年   14篇
  1985年   16篇
  1984年   12篇
  1981年   9篇
  1979年   10篇
  1978年   7篇
  1977年   7篇
  1975年   7篇
  1974年   9篇
  1973年   10篇
  1972年   10篇
  1967年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
多烯脂肪酸对脑血栓伴高脂血症病人降脂作用的疗效观察   总被引:2,自引:0,他引:2  
目的:研究多烯脂肪酸胶囊对脑血栓伴高脂血症病人的降脂作用。选血脂康作对照。方法:60例脑血栓伴高脂血症病人随机分为二组:治疗组(n=31)及对照组(n=29)。服药前及服药后4周,8周查血脂。结果:⑴服药4周后TC和LDL-C分别降低21.02%和28.93%(多烯脂肪酸组)。⑵多烯脂肪酸组降低了34.06%的血清TG水平,效果显,结论:多烯脂肪酸胶囊降TG和LDL-C水平与血脂康作用相近,其降  相似文献   
92.
Between 1983 and 1993, 41 patients underwent a first-stage Belt-Fuqua operation for penile hypospadias repair and 39 completed the second stage. Minor complications were observed after the first stage. The primary success rate following the second stage was 82%. Major complications noted after the second stage consisted mainly of fistula formation. The surgical technique is described and alternative methods are discussed.  相似文献   
93.
The effect of sulfur dioxide (SO2) on somatosensory-evoked potentials (SEPs), thiobarbituric acid reactive substances (TBARS), and the activities of Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were investigated in young (3 months), middle-age (12 months), and old (24 months) Swiss male albino rats. Ten ppm SO2 was administrated to the animals of SO2 groups in an exposure chamber for 1 h/day × 7 days/week × 6 while control groups were exposed to filtered air in the same condition. SO2 exposure caused increased levels of brain Cu,Zn-SOD activity and decreased levels of brain GSH-Px activity in all experimental groups with respect to their corresponding control groups. Brain CAT activities were unaltered. Brain TBARS levels of all SO2-exposed groups were significantly increased in comparison with their respective control groups. The mean latencies of P1, P2, and N2 components in the older group were either significantly different from the young or from the middle-age groups. The mean latency of the N1 component in the older group and that of P1 and N1 in the middle-age group were significantly increased compared with the young group. SO2 exposure caused the prolongation of all components in the young group, whereas it affected only the P2 component in the middle-age group, but it did not result in any latency change in the older group in comparison with their corresponding control groups. Received: 22 December 1998/Accepted: 7 April 1999  相似文献   
94.
Butyrylcholinesterase (BChE, EC 3.1.1.8) has been purified about 6600-fold from human serum with a procedure including ammonium sulfate fractionation (55-70%) with acid step at pH 4.5 and procainamide-Sepharose 4B affinity chromatography. The purified enzyme exhibited negative cooperativity with respect to butyrylthiocholine (BTCh) binding at pH 7.5. Ks was found to be 0.128 +/- 0.012 mM. Inhibition kinetics of the enzyme by Cd2+, Zn2+ and Al3+ were studied in detail. The 1/v vs 1/[BTCh] plots in the absence (control plot) and in the presence of different concentrations of cations intersected above 1/[BTCh]-axis. The data were analyzed by means of a nonlinear curve fitting program. The results demonstrated that all of the three cations are the linear mixed-type inhibitors of BChE. Ca2+ and Mg2+ had no effect on the enzyme activity in the experimental conditions. But when the enzyme was inhibited by 0.5 mM Cd2+ or Zn2+, Ca2+ and Mg2+ partially reactivated the inhibited allosteric form of BChE. Results were compared with data obtained from brain BChE purified from sheep.  相似文献   
95.
In dentistry, acrylates have been used for preparing denture bases for 50 years. Although polymethylmethacrylates (PMMA) are known to be an ideal base material, they possess some undesirable mechanical properties, especially their impact strength and tensile strength, which appear to be unsatisfactory for some applications. Additives and fibers have therefore been used to enhance and improve these properties over the last two decades. The present article describes the mechanical properties, impact and tensile strength of PMMA reinforced with chopped ultra-high molecular weight polyethylene fiber (6 mm long). It was found that, although the processing involved for high loading of fibers into the PMMA was difficult, the resulting improvement of impact strength was substantial.  相似文献   
96.
用氩激光激射恒河猴眼功能小梁网制作开角青光眼模型。取6 只猴12 只眼用于模型制作。激射部位是小梁网的后半部即功能小梁网区, 相邻两激射点的烧灼斑相连接,范围是360°。两周后重复激射, 共3 至5 次。激光参数是:光斑直径50 μm , 能量800 m W, 时间0.5~1.0 s。每次激射前及最后一次激射之后平均38 d (21~97 d) 进行眼压测量, 眼底杯盘比值测量及房角观察。有4 只猴8 只眼激射后眼压持续升高, 眼底杯盘比值增大, 激射后房角仍为宽角。实验表明猴开角青光眼模型的制作是成功的  相似文献   
97.
98.
99.
100.
The constant release of nitric oxide (NO) is essential to maintain basal cerebrovascular tone. Oxyhaemoglobin, liberated by lysis of red blood cells after subarachnoid haemorrhage binds NO and prevents its entry into vascular smooth muscle cells. While endothelium-dependent vasoconstriction is preserved, decreased levels of NO inhibit endothelium-dependent relaxation and may cause vasospasm. S-nitrosothiols are potent vasodilators and precursors of NO. The authors' aim was to determine whether S-nitroso-N-acetylpenicillamine (SNAP), a stable S-nitrosothiol compound, could reverse vasospasm in an experimental vasospasm model in rabbit. Experimental subarachnoid haemorrhage (SAH) was induced in 37 New Zealand white rabbits. The animals were divided into four groups. Control (no SAH), SAH only, SAH plus saline and SAH plus SNAP. SNAP (15 micrograms/kg/min) or 0.09% saline (equal volume) was infused 46 hours after induction of SAH. All animals were killed by perfusion fixation 48 hours after SAH occurred. Basilar arteries were removed, sectioned and their cross sectional areas were evaluated in a blind manner, by light microscopy and by using computer assisted morphometry. Experimental SAH elicited vasospasm in all animals of SAH only and SAH plus saline group. In animals treated with SNAP, arterial narrowing was markedly attenuated without producing systemic hypotension. This widening achieved statistical significance when compared to the arteries of the SAH only and SAH plus saline group (p < 0.01). This study indicates that the NO donor SNAP is a potentially useful drug to reverse cerebral vasospasm due to SAH.  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