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   17471篇
  免费   1450篇
  国内免费   202篇
耳鼻咽喉   41篇
儿科学   344篇
妇产科学   770篇
基础医学   1949篇
口腔科学   114篇
临床医学   1426篇
内科学   2136篇
皮肤病学   582篇
神经病学   1333篇
特种医学   285篇
外国民族医学   2篇
外科学   1150篇
综合类   1711篇
现状与发展   1篇
一般理论   5篇
预防医学   5544篇
眼科学   68篇
药学   951篇
  3篇
中国医学   314篇
肿瘤学   394篇
  2024年   43篇
  2023年   326篇
  2022年   589篇
  2021年   767篇
  2020年   764篇
  2019年   713篇
  2018年   677篇
  2017年   699篇
  2016年   697篇
  2015年   545篇
  2014年   980篇
  2013年   1532篇
  2012年   926篇
  2011年   1005篇
  2010年   806篇
  2009年   787篇
  2008年   754篇
  2007年   746篇
  2006年   645篇
  2005年   512篇
  2004年   495篇
  2003年   404篇
  2002年   352篇
  2001年   327篇
  2000年   257篇
  1999年   221篇
  1998年   205篇
  1997年   223篇
  1996年   201篇
  1995年   169篇
  1994年   179篇
  1993年   157篇
  1992年   137篇
  1991年   113篇
  1990年   98篇
  1989年   96篇
  1988年   94篇
  1987年   85篇
  1986年   93篇
  1985年   91篇
  1984年   103篇
  1983年   38篇
  1982年   65篇
  1981年   80篇
  1980年   83篇
  1979年   51篇
  1978年   44篇
  1977年   44篇
  1976年   39篇
  1975年   24篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Electroretinograms and retinal oscillatory potentials to full-field flash stimulation were recorded by dermal electrodes in a population of subjects (1 to 84 yrs) balanced for age and sex (119 females, 133 males), without evidence or history of ocular and/or relevant systemic diseases. The electroretinogram latencies and b-wave amplitude increased, while the a-wave amplitude decreased linearly with age. The oscillatory potential amplitude initially increased, to decrease approximately at the age of 50, with an inverted U-shaped distribution.Presented in part at the XXV ISCEV Symposium, Sarasota (Florida), April 26–30, 1987.  相似文献   
32.
Among British-qualified doctors of 1974 and 1977, about 80% held postgraduate qualifications of some kind. The commonest qualifications were DRCOG, MRCP and MRCOG. There were considerable differences between medical schools in the numbers of qualifiers taking various examinations. Apart from the MRC Psych, DRCOG and Family Planning Certificate, qualifications were more commonly held by men than women. Tables show the type of work being done 9-13 years after leaving medical school by holders of various postgraduate qualifications; e.g. 60% of MRCP holders were working in medicine or a medical specialty and 84% of FRCS holders in general surgery or a surgical specialty. Discussion deals with the plurality, specificity, variability, perceived necessity, sufficiency, international utility and career significance of British postgraduate qualifications.  相似文献   
33.
34.
35.
乳房体积生物立体测量系统的研制   总被引:7,自引:1,他引:6  
目的 利用立体视觉方法建立乳房体积测量系统 ,并探讨其准确性和精确程度。方法 通过采用两台CCD摄相机从两个不同视角观察乳房模型 ,运用激光投射仪和光栅获得计算机能识别的平行采样点 ,依靠计算机图像处理技术和生物立体测量技术 ,求取乳房模型表面采样点的三维坐标 ,设计乳房体积测量运算模式 ,在Windows下编制程序 ,建立乳房体积测量和分析系统 ,应用所建的测量系统和水体积置换术分别对 12例乳房模型进行体积测量 ,并将两种测量方法及其结果进行比较和统计分析 ,观察其精确性和准确性。结果 本系统测量乳房体积实现了数据的快速处理 ,测试空间范围为12 0mm× 14 0mm× 80mm ,特点是快速、非接触性和非侵入性。与水体积置换方法比较 ,P =0 .4 73>0 .0 5 ,差值的 95 %可信区间为 - 14 .0 2~ 7.0 8ml。结论 本系统可应用于乳房体积测量 ,简捷而且精确 ,为临床工作提供了一种有效手段 ,并为软组织形态分析的开展提供了一种新的理论基础。  相似文献   
36.
广东省放射工作人员健康状况调查   总被引:13,自引:2,他引:11  
目的 了解长期小剂量电离辐射对放射工作人员健康的影响 ,为保障其工作者的健康和改进防护措施提供依据。方法 通过职业流行病学现况调查的方法 ,按照广东省放射工作人员职业健康体检规范要求 ,对 2 0 0 2年广东省999例放射工作人员的职业健康状况进行分析。结果 随着工龄增加 ,放射工作人员眼科检查的异常率增加。血液常规检查和细胞遗传学指标 (外周血淋巴细胞微核率 )及眼晶状体混浊率 ,部分组间指标差异有统计学意义。男性微核率的异常率 >15年组是 <5年组的 5 2倍 ,是 5~ 15年组的 1 4倍 ,女性微核率异常率 >15年组是 <5年组的 3 3倍 ,是 5~15年组的 2 5倍。结论 加强放射卫生监督管理 ,重点保护暴露工龄较长的放射工作人员 ,以减低放射对该人群的影响  相似文献   
37.
A previous study showed that adult female dancers have a high percentage of type I fibres in vastus lateralis. similar to that of endurance-trained female runners ar female cross-country skiers. It is not known if dancers already at an early age are characterized by a high percentage of type I fibres or develop a high percentage of type I fibres as a consequence of dance training. Furthermore. the muscle fibre composition of male dancers has not previously been studied. Therefore the aim of the study was to analyse skeletal muscle fibre characteristics in 10-year-old and 20-year-old dancers of both sexes. Age-matched boys and girls whose physical activity was average for their age groups served as controls. Muscle biopsies for histochemical analysis were obtained from vastus lateralis using the percutaneous needle technique. The major finding of the present study was that the vastus lateralis of young dancers of both sexes had a higher percentage of type I fibres than that of controls. Moreover. the higher type I percentage was seen not only in 20 year aids. but also in 10 year aids. who had begun their dance training at a professional level only a few weeks earlier. No significant difference in this respect was found between female and male dancers. In conclusion. the muscle fibre type composition in young dancers of both sexes differs from that of the average individual of the same age and is characterized by a high percentage of type I fibres.  相似文献   
38.
In this century, the use of pesticides and fertilizers (agrochemicals) is indispensable because they are seen as a panacea for protecting crops from insects and diseases. However, the manner in which these agrochemicals are handled poses significant health risks to manufacturers, transporters, vendors and farmers. In Kenya, for example, coffee factory workers (specifically storekeepers) apportion the agrochemicals and sell them to the coffee farmers. The process of apportioning and other factors expose these workers to health risks. In order to evaluate the extent of the problem, a pilot study was undertaken in the Githuguri location. The results showed that lack of use of protective clothing, poor handling of agrochemicals and poorly designed storage facilities were very common. As a result, 95% of the workers interviewed reported a variety of agrochemical health related problems. In conclusion, the government and the public role regarding possible preventive measures were proposed.  相似文献   
39.
SRY基因诊断在临床中的应用   总被引:1,自引:0,他引:1  
应用聚合酶链式反应(PCR)扩增技术,对10例染色体核型为46,XY和1例为46,XX/46,XY的性反转、睾丸女性化、两性畸形及男性生殖器发育不良的患者进行了性别决定区(SRY)基因检测。结果表明9例46,XY和1例46,XX/46,XY患者的SRY基因存在,1例46,XY女性患者的SRY基因缺失。该结果表明能够用分子生物学技术对性反转、性发育异常的病因进行分析  相似文献   
40.
Sex-specific effects for body mass index (BMI) were explored in a newly established, population-based Norwegian twin panel. The sample includes 5,864 individuals, aged 18–25 years, who responded to a questionnaire containing items for zygosity classification, height, weight, health, health-related behaviors, well-being, and demographic information. Among the 2,570 intact pairs who returned the questionnaire there were 416 identical (MZ) male pairs, 387 fraternal (DZ) male pairs, 528 MZ female pairs, 443 DZ female pairs, and 796 unlike-sexed pairs. Alternate sets of models testing for either sex-specific genetic or environmental parameters were evaluated using structural equation analysis. Results from the most parsimonious model indicated that the genes contributing to variation in BMI are not identical for men and women; rather, some genetic effects were shared by the sexes and some were unique to each sex. Total variation in BMI could be explained by sex-specific additive genetic effects, as well as genetic and non-shared environmental effects common to men and women. Estimates of heritability were .708 for men and .789 for women, and the male-female genetic correlation was 0.622. The series of models specifying sex-specific shared environment also fit the data and suggests that shared environmental factors may be important for males but not for females. The findings raise questions concerning the relationship between sex-specific effects for BMI and sex differences in health outcomes. ©1995 Wiley-Liss, Inc.  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