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   10198篇
  免费   1105篇
  国内免费   267篇
耳鼻咽喉   57篇
儿科学   124篇
妇产科学   82篇
基础医学   1076篇
口腔科学   115篇
临床医学   1129篇
内科学   1496篇
皮肤病学   182篇
神经病学   942篇
特种医学   342篇
外国民族医学   4篇
外科学   815篇
综合类   1004篇
预防医学   934篇
眼科学   601篇
药学   1289篇
  13篇
中国医学   465篇
肿瘤学   900篇
  2024年   50篇
  2023年   269篇
  2022年   396篇
  2021年   617篇
  2020年   535篇
  2019年   506篇
  2018年   491篇
  2017年   477篇
  2016年   447篇
  2015年   437篇
  2014年   655篇
  2013年   737篇
  2012年   527篇
  2011年   642篇
  2010年   447篇
  2009年   431篇
  2008年   473篇
  2007年   445篇
  2006年   391篇
  2005年   317篇
  2004年   296篇
  2003年   232篇
  2002年   203篇
  2001年   157篇
  2000年   147篇
  1999年   140篇
  1998年   106篇
  1997年   92篇
  1996年   75篇
  1995年   93篇
  1994年   63篇
  1993年   60篇
  1992年   68篇
  1991年   51篇
  1990年   56篇
  1989年   47篇
  1988年   42篇
  1987年   33篇
  1986年   23篇
  1985年   54篇
  1984年   39篇
  1983年   24篇
  1982年   35篇
  1981年   37篇
  1980年   24篇
  1979年   22篇
  1978年   12篇
  1977年   11篇
  1976年   11篇
  1975年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Functional dyspepsia (FD) is associated with impaired gastric accommodation and autonomic dysregulation. The aim of this study was to investigate the effects of autonomic manipulation on distension-induced gastric accommodation in subjects with and without FD, using a newly developed gastric barostat paradigm. Twelve healthy subjects (HS) and 18 subjects with FD had four barostat examinations each: no intervention, intravenous atropine (1 mg), vagal stimulation (mental relaxation with deep breathing) and acute stress stimulation (serial subtraction task). Intrabag pressure increased from 1 to 15 mmHg in 5 min (ramp phase), and was maintained at 15 mmHg for 5 min (tonic phase). Volume responses were analysed using predefined parameters. There were no significant group differences in accommodation variables between HS and subjects with FD. The FD group could be subdivided into two distinct subgroups: subgroup 1 (n = 7, 38%) with low maximum volume and accommodation rate, and subgroup 2 with normal accommodation (n = 11). In subgroup 1, but not in subgroup 2 atropine increased maximum volume and accommodation rate substantially. Neither mental stress nor mental relaxation changed any of the accommodation variables. In a subgroup of subjects with FD, impairment of distension-induced gastric accommodation can be improved by cholinergic blockade, but not by acute physiological autonomic manipulation.  相似文献   
12.
论高校大学生绿色网络环境的营造   总被引:2,自引:0,他引:2  
介绍了网络文化的迅猛发展对高校大学生的学习方式、生活方式、交往方式产生了巨大冲击,尤其对大学生的身心发展产生了不可忽视的消极影响。指出在高校信息化校园建设中,要加强网络文明的建设,提倡和重视绿色网络,并且从高校大学生的实际出发,努力营造一个健康、文明、有序、安全、具有活力、没有污染的绿色网络环境。  相似文献   
13.
Up to 30% of patients with temporal lobe epilepsy (TLE) remain without remarkable changes in MRI. In this study we investigated the role of (1)H-MR spectroscopy ((1)H-MRS) in lateralizing the affected hemisphere in the mentioned patient group. Twenty-two consecutive patients diagnosed with TLE were investigated by high resolution MRI and (1)H-MRS. We examined the incidence and diagnostic accuracy of temporal metabolite alterations determined by Linear Combination of Model Spectra (L C Model) via water reference. Metabolite values of each hemisphere of TLE patients were compared with healthy controls. Results of metabolite alterations were related to intensive video EEG focus localization. Reduction of N-acetylaspartate + N-acetylaspartyl-glutamate (tNAA) in the affected hemisphere revealed identification in six of nine patients (66%) with unilateral TLE. Group comparison revealed a significant reduction of tNAA (6.1+/-0.8*) in the involved temporal lobe compared with controls (6.67+/-0.4*, P=0.026). Choline levels were significantly increased in the affected hemisphere (1.42+/-0.17*) compared with healthy controls (1.22+/-0.17*, P=0.035). The results of our study show that (1)H-MRS is able to identify the affected hemisphere of MRI negative TLE patients and can be used as an additive tool in multimodal focus localization.  相似文献   
14.
The influence of continuous variation in dioptric demand on the accommodative hysteresis induced at near distances was examined in 14 visually-normal young adults. Tonic accommodation was measured before and after 10 minutes of sustained focus using a constant stimulus at 5 D, 6.5 D, and 8 D, as well as a stimulus which slowly and alternately increased and decreased over the continuous range from 5 D to 8 D. For approximately half the subjects, dioptric demand had to be very high (8 D) under static conditions to produce moderate but significant hysteresis, yet little or no attenuation of the effect occurred under the dynamic condition. For other subjects who consistently showed very large tonic changes (1.4 D or more) under static conditions, the hysteresis effect generated under dynamic conditions was greatly reduced (approximately 50 per cent) in magnitude. These findings suggest that the degree to which continuous variation in dioptric demand will disrupt the adaptive process may depend on individual differences in the rate and/or maximum level of tonic accommodative change. Such a relationship could have bearing on the particular strategy recommended for individuals who tend to experience blur at distance following nearwork.  相似文献   
15.
16.
This is a report on a comparative study of the reactivity of TRUE Test and Finn Chamber patch test techniques. 413 patients attending a contact dermatitis clinic in Singapore were simultaneously patch tested with panels 1 and 2 of the TRUE Test standard series and with corresponding allergens (Hermal, Hamburg) using Finn Chambers. The left/right application of the TRUE Test and Finn Chambers was randomized. The concordance of positive patch test reactions to the 2 test techniques was studied. The number of patient with positive reactions was 38% and 42% for TRUE Test and Finn Chamber techniques, respectively (n.s.). The overall concordance of positive patch test reactions was 64% (209/328). 13% (42/328) of positive reactions appeared on TRUE Test only and 24% (77/328) on Finn Chamber only. When only relevant positive reactions were considered, the concordance rate was 67%; 11.6% of positive reactions appeared on TRUE Test only and 21% on Finn Chamber only. Positive reactions to p-phenylenediamine (PPD) and neomycin were more frequent with the Finn Chamber technique than with TRUE Test, i.e., false negative reactions to PPD and neomycin were more likely to occur with TRUE Test. It appeared that the TRUE Test and Finn Chamber techniques were comparable when used for patch testing. However false negative and false positive patch test reactions can occur when using either technique.  相似文献   
17.
作者对自制新荧光剂EPQS进行了性能测试。结果:量子产率为0.21;最大激发波长和荧光波长分别为375nm和484nm,stokes位移109nm;检测生物化合物常用的缓冲溶液对荧光峰位无影响,对荧光强度影响很小;温度的影响也小(18~43℃,FRI61.5~58.1),PH的影响也不大。说明EPQS不仅荧光参数好,而且稳定性也好。适合在较广泛的环境条件下使用。  相似文献   
18.
19.
R波相关振动法血压测量   总被引:1,自引:0,他引:1  
为了提高振地血压测量的准确性,提出了一咱基于心电R波与血压振动波之间相关性,识别振动信号的一种抗干扰方法=-R波相关法,结合振动波形特征识别,该方法可有效地提取信号,消除干扰影响,该算法已在16位8098单片机上实现,本文同时给出了程序的详细流程图。  相似文献   
20.
目的通过化学方法制成动物核性白内障模型,探讨相对能量复合指数(RECP)与角膜内皮细胞活性的关系。方法将5种化学物质注入晶状体,以透过黑白条纹的清晰程度判断晶状体混浊程度并分级。然后将实验眼球分为6组(Ⅰ组为对照组;Ⅱ-Ⅵ为实验组),行标准超声乳化白内障摘除手术。手术后立即取下角膜,作锥蓝-茜素红联合染色标本和扫描电镜标本。结果晶状体内注入甲醛、冰醋酸、无水乙醇、丙酮和苯扎溴铵均能形成晶状体混浊,其中:冰醋酸致晶状体混浊能力最弱,无水乙醇、丙酮次之,甲醛、苯扎溴铵最强。当RECP≤90时,锥蓝-茜素红双重染色和扫描电镜均表明角膜内皮细胞活性好,其形态和细胞联接均无改变。当RECP=120时,角膜内皮细胞形态尚正常,但是细胞联结和胞膜部分破坏。当RECP=150时,角膜内皮细胞严重损伤。结论用化学方法制作核性白内障模型供过渡训练使用是可行的。当RECP超过某一数值(>90)时,即与角膜内皮细胞的活性成负相关。  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