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   43867篇
  免费   4141篇
  国内免费   2771篇
耳鼻咽喉   398篇
儿科学   483篇
妇产科学   416篇
基础医学   4808篇
口腔科学   757篇
临床医学   5085篇
内科学   6899篇
皮肤病学   668篇
神经病学   2345篇
特种医学   1911篇
外国民族医学   16篇
外科学   5613篇
综合类   7413篇
现状与发展   4篇
一般理论   5篇
预防医学   2883篇
眼科学   1012篇
药学   4223篇
  48篇
中国医学   2182篇
肿瘤学   3610篇
  2024年   157篇
  2023年   731篇
  2022年   1712篇
  2021年   2274篇
  2020年   1779篇
  2019年   1497篇
  2018年   1585篇
  2017年   1404篇
  2016年   1441篇
  2015年   2037篇
  2014年   2438篇
  2013年   2438篇
  2012年   3550篇
  2011年   3693篇
  2010年   2438篇
  2009年   2032篇
  2008年   2527篇
  2007年   2450篇
  2006年   2312篇
  2005年   2084篇
  2004年   1535篇
  2003年   1482篇
  2002年   1203篇
  2001年   907篇
  2000年   816篇
  1999年   658篇
  1998年   476篇
  1997年   418篇
  1996年   364篇
  1995年   338篇
  1994年   252篇
  1993年   169篇
  1992年   227篇
  1991年   201篇
  1990年   162篇
  1989年   156篇
  1988年   141篇
  1987年   133篇
  1986年   136篇
  1985年   97篇
  1984年   55篇
  1983年   45篇
  1982年   33篇
  1981年   35篇
  1980年   28篇
  1979年   28篇
  1978年   17篇
  1976年   12篇
  1975年   7篇
  1957年   7篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
目的 :探讨夜间电子生物阻抗测量装置 (NEVA)在阴茎勃起功能障碍的诊断中的应用价值。方法 :对 4 1例主诉阴茎勃起功能障碍者 (障碍组 ) 19例主诉无勃起功能障碍但有射精障碍者 (无障碍组 )进行NEVA检测。结果 :障碍组夜间试验中的夜间勃起的次数、阴茎勃起的最大体积改变、最长持续时间等客观指标均要差于无障碍组 ,差异有统计学意义 (P <0 .0 1)。结论 :NEVA为非侵入性检测、可鉴别心理性阴茎勃起功能障碍和严重的器质性勃起功能障碍 ,且对勃起功能障碍的定性和定量具有一定的客观性。  相似文献   
12.
13.
We treated 5 cases of severe hydronephrosis with balloon dilation. Those hydronephrosis were due to the ureteral stricture with small stone fragments after ESWL (Lithostar). In each case, in situ ESWL had been done on a long-lodged ureteric stone with severe hydronephrosis. And even after the disintegration of stone with ESWL, hydronephrosis remained due to ureteral stricture with small stone fragments. Balloon dilation was done through percutaneous nephrostomy tract in 4 cases and via retrograde transurethral routine in 1 case. Balloon dilation catheter (7 fr. 6 mm diameter 4-10 cm length, Bard Co.) was used. There was no need for stone extraction. After dilation, ureteric stents (8.2/7 fr.) were kept in place for 4-8 weeks. Intravenous urogram was taken on 4-8 weeks after removing ureteric stents. In all of the 5 cases, improvement of hydronephrosis was remarkable. And there was no residual stone fragments in 4 cases. It is concluded that balloon dilation for ureteral stricture with stone fragments after ESWL is very useful. For the valid evaluation of balloon dilation, further experience and longer observation are requisite.  相似文献   
14.
戴慧芳  王莹莹 《护理研究》2006,20(12):3238-3239
弥漫性轴索损伤(diffuse axonal injury,DAI)是以胼胝体、脑十等中线部位局灶性病变及脑白质广泛性轴索损伤为主,以原发昏迷时间长而又缺乏神经定位体征为其临床特征的一组原发性弥散性脑损伤。在重型颅脑损伤中占20%,病死率高达42%~62%。最常见于车祸颅脑损伤病人,也可见于高处坠落伤者。病人多合并其他部位损伤,特点为伤情重、变化快、并发症和休克发生率高,且病死率高。护理时矛盾多,易顾此失彼,影响临床治疗效果。为更好地总结对该类损伤病人的救治,  相似文献   
15.
目的探讨十二指肠镜下逆行胆胰管造影(ERCP)及取石(EST)引发急性胰腺炎的防治方法。方法对该院已行ERCP和EST的42例患者的临床资料进行回顾性分析。结果6例术后并发急性胰腺炎,其中1例死亡。结论ERCP和EST引发急性胰腺炎,主要有两种情况,一是化学刺激引发急性胰腺炎;另一方面为共同通道受阻引发急性胰腺炎,只有在操作中认真防范,术后仔细观察、处理,该并发症是可以防治的。  相似文献   
16.
病例:男,73岁,因发现原膀胱造瘘口处可复性肿块3年而入院.7年前因前列腺癌于外院行双侧睾丸切除加膀胱造瘘术.3年前无明显诱因下出现造瘘口外侧无痛性肿物,站立时出现,平卧后可自行回纳,肿块渐增大,无明显腹痛、腹胀等不适症状.半年前入院行前列腺电切术加造瘘口回纳术.  相似文献   
17.
Methyl tert-butyl ether which is a powerful cholesterol monohydrate solvent does not completely dissolve mixed cholesterol gallstones when directly infused into the biliary tree. In this work, we compared the effect of various solvents containing different proportions of methyl tert-butyl ether and dimethylsulfoxide in anhydrous and aqueous systems on the in vitro solubilization of human cholesterol stones. The dissolution rates of cholesterol obtained in the presence of methyl tert-butyl ether was markedly decreased when 10 p. 100 water was added. In contrast, the addition of dimethylsulfoxide (30 p. 100) to methyl tert-butyl ether-water system enhanced the stone-solvent contact, improved the cholesterol dissolution rates and left less stone debris. A subsequent dissolution with an alkaline, pH = 8.8, aqueous dimethylsulfoxide-ethylenediaminetetraacetic acid solution strongly reduced the non cholesterol residues. In vivo, nearly complete dissolution of human cholesterol stones implanted in the gallbladder of rabbits was obtained within 8 hours when methyl tert-butyl ether/dimethylsulfoxide (70/30) solvent was infused at a rate of 0.6 ml/h/kg. With methyl tert-butyl ether, only 84 p. 100 of the original stone weight was dissolved. The infusion of these solvents leads to morphological changes in the gallbladder wall with some focal ulcerations. These alterations can be almost completely recovered after two weeks. No histologic evidence of hepatic, duodenal or renal damage was found. We conclude that the mixture methyl tert-butyl ether/dimethylsulfoxide (70/30) constitutes a good solvent for mixed cholesterol stones. Compared with pure methyl tert-butyl ether, the mixed system allows for a more rapid and a more complete dissolution of gallstones.  相似文献   
18.
In this paper we propose a method for construction of feed-forward neural classifiers based on regularization and adaptive architectures. Using a penalized maximum likelihood scheme, we derive a modified form of the entropic error measure and an algebraic estimate of the test error. In conjunction with optimal brain damage pruning, a test error estimate is used to select the network architecture. The scheme is evaluated on four classification problems.  相似文献   
19.
行为实验己经证明,锌过多或缺锌均可影响脑功能。锌作为体内重要的微量元素,影响多种酶的活性及蛋白质和核酸的台成。本实验通过体外分离大鼠脑海马突触体,观察不同浓度锌离子对Ca2 -Mg2 ATP酶的活性和3H-Leu掺入突触蛋白合成的影响.结果表明:1.锌离子浓度在25μmol/L时增加该酶的活性(<0.01),并促进3H-Leur掺入蛋白质的合成(<0.05)。2.锌离子在50,100,200μmol/L的较高浓度时对Co2 -M2 ATP酶的活性有显著的抑制作用(分别为:P<0.05.P<0.01,P<0.01),仅200μmol/L对3H—Leu掺入突触蛋白合成有抑制作用。本研究提示:适量的锌对突触体功能的维持是必要的,但剂量过高则起相反作用。  相似文献   
20.
We reviewed the radiographs of 25 hips of 20 patients who had received revisions of the acetabular components of total hip replacement supplemented by allograft for bone defects. Bone defects in 20 hips (80%) were classified into type D (cranio-central defect) according to Itoman's classification. In eight, sockets were installed directly on the allografts (group A). A metallic supporting device was used for reinforcing the grafts in 17 hips (group B). The position of the acetabular socket was measured on a radiograph, taken immediately after revision surgery and again at the latest follow-up. Using a MEM template, cranial and central migrations were determined. Mean cranial migration in hips of group A was 3.6 mm. Group B was 0.2 mm. Maintenance of thickness of the allografts was 60.6% in the cranial region and 75% in the central in group A. In the hips of group B, however, almost 100% of the initial thickness was maintained cranially and centrally. Allograft reconstruction of acetabular bone defect in revision total hip replacement is a beneficial procedure. The remaining pelvic bone is usually in poor condition, therefore, it is necessary to ensure primary fixation by the metallic supporting device.  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