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   43694篇
  免费   2004篇
  国内免费   319篇
耳鼻咽喉   338篇
儿科学   800篇
妇产科学   507篇
基础医学   5671篇
口腔科学   1222篇
临床医学   2632篇
内科学   10986篇
皮肤病学   968篇
神经病学   2873篇
特种医学   1450篇
外科学   7861篇
综合类   177篇
一般理论   1篇
预防医学   1183篇
眼科学   792篇
药学   2714篇
中国医学   154篇
肿瘤学   5688篇
  2023年   232篇
  2022年   590篇
  2021年   990篇
  2020年   509篇
  2019年   735篇
  2018年   972篇
  2017年   729篇
  2016年   910篇
  2015年   935篇
  2014年   1246篇
  2013年   1611篇
  2012年   2571篇
  2011年   2911篇
  2010年   1664篇
  2009年   1382篇
  2008年   2549篇
  2007年   2817篇
  2006年   2644篇
  2005年   2843篇
  2004年   2726篇
  2003年   2727篇
  2002年   2750篇
  2001年   764篇
  2000年   688篇
  1999年   762篇
  1998年   663篇
  1997年   534篇
  1996年   497篇
  1995年   435篇
  1994年   380篇
  1993年   352篇
  1992年   410篇
  1991年   363篇
  1990年   346篇
  1989年   333篇
  1988年   282篇
  1987年   256篇
  1986年   219篇
  1985年   219篇
  1984年   190篇
  1983年   158篇
  1982年   102篇
  1981年   110篇
  1980年   111篇
  1979年   119篇
  1978年   75篇
  1977年   59篇
  1975年   56篇
  1973年   55篇
  1971年   53篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The effects of potassium in reperfusion solution (RS) and the influence of sodium on this effect were studied. Experimental time course was as followed: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution followed by global ischemia for 33 or 35 min at 37.5 degrees C, 15 min early Langendorff reperfusion with several different potassium concentration modified with Krebs Henseleit Bicarbonate Buffer (KHBB) containing 145 mM and 110 mM sodium and 5 min late reperfusion with KHBB, followed by 20 min working perfusion. Potassium in RS possessed bell shaped dose response nature with optimal concentration of 10 mM in the condition of 145 mM sodium but 6 m in the condition of 110 mM in terms of percent recovery of aortic flow. Although higher potassium reperfusion produced less Creatine Kinase leakage.  相似文献   
62.
Two elderly women complaining of intermittent claudication complicated with persistent sciatic artery are herein reported. A direct femoral arteriogram showed hypoplasty of the superficial femoral artery and an unnatural anatomical relationship between the distal superficial femoral artery and the proximal popliteal artery, thus suggesting the presence of persistent sciatic artery. The diagnosis of persistent sciatic artery was finally made based on the aortography findings including the iliac arterial system and computed tomography (CT) scan. Magnetic resonance imaging (MRI) was helpful to demonstrate the entire image of this anomaly in cases with non-thrombolized sciatic artery. These diagnostic methods were useful in designing the optimal surgical strategy. The first case with a gluteal pulsating mass underwent exclusion of the persistent sciatic artery including the aneurysm through a retroperitoneal approach with a combination of femorotibial bypass, while the second case with thrombosed persistent sciatic artery only underwent femoropopliteal bypass. To recognize such a rare lesion, awareness of the differential diagnosis is important, and to provide appropriate treatment, an accurate whole image including adequate angiography, a CT scan, and magnetic resonance imaging is necessary.  相似文献   
63.
Intraosseous ganglia of the glenoid are rare, and their etiology is unknown. This report describes a case of an intraosseous ganglion about to cause fracture of the glenoid. The patient was a 61-year-old woman with a painful left shoulder with a limited range of motion. Her symptoms did not improve after non-operative treatment. Arthroscopic examination showed a cartilage defect and erosion in the posteroinferior portion of the glenoid, behind which computed tomography (CT) showed a cystic lesion of the glenoid. There was no communication between the cyst and the joint space. The patient was treated by curettage and an autogenous cancellous bone graft from the iliac crest. Two years after the operation, the patient was almost free from pain, and CT showed good integration of the bone graft.  相似文献   
64.
The possible roles of cytochrome P450 (P450) enzymes in the metabolic activation of N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) by rat liver microsomes have been examined in a system containing the bacterial tester strain Salmonella typhimurium NM2009, a newly developed strain showing high O-acetyltransfer activities. The DNA-damaging activity could be determined by measuring expression of the umu gene in a plasmid containing the fused umuC-lacZ gene construct in the bacteria. The following lines of evidence support the view that both NDMA and NDEA are principally oxidized to reactive products by P450 2E1 in rat liver microsomes. First, NDMA and NDEA were activated by rat liver microsomes in a protein- and substrate-dependent manner and the former chemical was more active than the latter; both activities were induced in rats treated with P450 2E1 inducers such as ethanol, acetone and isoniazid and by starvation. Second, activation of NDMA and NDEA were both inhibited significantly by antibodies raised against rat P450 2E1 and by P450 2E1 inhibitors such as diethyldithiocarbamate and 4-methylpyrazole in rat liver microsomes. Finally, in reconstituted monooxygenase systems containing purified rat P450 enzymes, P450 2E1 gave the highest rates of the activation of both NDMA and NDEA; the addition of rabbit cytochrome b5 to the system caused about a 1.5-fold increase in both reactions. In separate experiments we also found that N-nitrosomethylacethoxymethylamine, a compound that reacts with DNA after ester cleavage, is more genotoxic in S.typhimurium NM2009 than in S.typhimurium NM2000, a strain that is defective in O-acetyltransferase activity. Part of the pathway involved in the activation of nitrosamines is suggested to be acetylation of alkyldiazohydroxides formed by P450 or acetylesterase, because the genotoxic activity of N-nitrosomethylacethoxymethylamine in S.typhimurium NM2009 could be inhibited by the O-acetyltransferase inhibitor pentachlorophenol. These results indicate that NDMA and NDEA are oxidized to gentoxoic products by rat liver microsomes and that a P450 2E1 enzyme plays a major role in the activation of these two potent carcinogens. The activation pathway of N-nitrosodialkylamines through acetylation by O-acetyltransferase has been proposed. This simple bacterial system for measuring genotoxicity should facilitate studies on the activation of N-nitroso alkylamines.  相似文献   
65.
66.
67.
In 2002, psychiatrically disabled athletes joined an historic first open game of volleyball at the national sports games for the disabled. Compared to the competitive sports and Paralympic Games that physically and intellectually disabled athletes have participated in, activities for the psychiatrically disabled have not been well-organized. In this paper, we examine a number of problems that have arisen when the psychiatrically disabled joined competitive sports games. We identify two major characteristics of the psychiatrically disabled of particular relevance when organizing competitive sports activities. First, all psychiatrically disabled athletes need treatment of their individual diseases. For example, psychiatric symptoms fluctuate markedly over time, unlike physical or intellectual disabilities, whose symptoms are much more stable. Exacerbations of psychiatric illness are also likely to occur due to the stresses of competitiveness. Second, psychiatric disabilities are manifestations of disorders in the central nervous system, which makes the classification of psychiatric disabilities less straightforward than classification of the physically disabled. These two characteristics require special attention when organizing competitive athletic challenges that include the psychiatrically disabled. However, promoting sports activities that include the psychiatrically disabled would be expected to reduce the prejudice toward and subsequent social disadvantages experienced by psychiatric patients. Thus, with careful planning to successfully integrate psychiatrically disabled athletes, we expect increased promotion of such sports activities in the future.  相似文献   
68.
Changes in MAP2 and clathrin immunoreactivity were studied in gerbil hippocampus after transient cerebral ischemia. MAP2 immuno-reactivity decreased significantly by 1 h in the subiculum-CA1 and CA2 areas which correspond to reactive change, while no decrease was observed in CA1 until day 4. Before the initiation of delayed neuronal death, MAP2 immunoreactivity was not changed in CA1. On the other hand clathrin immunoreactivity increased in the pyramidal cell layer of CA1 by 3 h after ischemia and remained high for 2 days. Clathrin immunoreactivity in the pyramidal cell layer of CA1 diminished after delayed neuronal death. The transient change of clathrin was noted especially in CA1 in the period prior to delayed neuronal death. These results imply an abnormal change in clathrin turnover after ischemia, which may participate in the pathogenesis of delayed neuronal death.  相似文献   
69.
70.
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