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   20097篇
  免费   1290篇
  国内免费   440篇
耳鼻咽喉   101篇
儿科学   602篇
妇产科学   304篇
基础医学   1585篇
口腔科学   536篇
临床医学   1814篇
内科学   2982篇
皮肤病学   189篇
神经病学   1480篇
特种医学   1459篇
外科学   1910篇
综合类   1853篇
现状与发展   1篇
一般理论   2篇
预防医学   3386篇
眼科学   203篇
药学   1727篇
  7篇
中国医学   416篇
肿瘤学   1270篇
  2024年   56篇
  2023年   294篇
  2022年   450篇
  2021年   594篇
  2020年   680篇
  2019年   669篇
  2018年   598篇
  2017年   629篇
  2016年   665篇
  2015年   605篇
  2014年   1234篇
  2013年   1421篇
  2012年   1167篇
  2011年   1255篇
  2010年   937篇
  2009年   931篇
  2008年   912篇
  2007年   1003篇
  2006年   869篇
  2005年   857篇
  2004年   771篇
  2003年   723篇
  2002年   546篇
  2001年   453篇
  2000年   365篇
  1999年   334篇
  1998年   305篇
  1997年   247篇
  1996年   196篇
  1995年   222篇
  1994年   210篇
  1993年   182篇
  1992年   212篇
  1991年   168篇
  1990年   114篇
  1989年   103篇
  1988年   121篇
  1987年   94篇
  1986年   77篇
  1985年   112篇
  1984年   74篇
  1983年   54篇
  1982年   65篇
  1981年   51篇
  1980年   45篇
  1979年   26篇
  1978年   39篇
  1977年   33篇
  1976年   17篇
  1975年   15篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
There is overwhelming evidence for the existence of substantial genetic influences on individual differences in general and specific cognitive abilities, especially in adults. The actual localization and identification of genes underlying variation in cognitive abilities and intelligence has only just started, however. Successes are currently limited to neurological mutations with rather severe cognitive effects. The current approaches to trace genes responsible for variation in the normal ranges of cognitive ability consist of large scale linkage and association studies. These are hampered by the usual problems of low statistical power to detect quantitative trait loci (QTLs) of small effect. One strategy to boost the power of genomic searches is to employ endophenotypes of cognition derived from the booming field of cognitive neuroscienceThis special issue of Behavior Genetics reports on one of the first genome-wide association studies for general IQ. A second paper summarizes candidate genes for cognition, based on animal studies. A series of papers then introduces two additional levels of analysis in the black box between genes and cognitive ability: (1) behavioral measures of information-processing speed (inspection time, reaction time, rapid naming) and working memory capacity (performance on on single or dual tasks of verbal and spatio-visual working memory), and (2) electrophyiosological derived measures of brain function (e.g., event-related potentials). The obvious way to assess the reliability and validity of these endophenotypes and their usefulness in the search for cognitive ability genes is through the examination of their genetic architecture in twin family studies. Papers in this special issue show that much of the association between intelligence and speed-of-information processing/brain function is due to a common gene or set of genes, and thereby demonstrate the usefulness of considering these measures in gene-hunting studies for IQ.  相似文献   
102.
Summary Electron microscopical studies on endocrine cell hyperplasia of duodenal adenomas from five patients with familial adenomatous polyposis were performed. All the endocrine cell types normally found in the duodenal mucosa were identified. A constant feature was proliferation of duodenal-enterochromaffin cells but an increase in the number of all other endocrine cell types apart from pyloricgastrin cells and somatostatin cells, was also observed. Certain types of intestinal endocrine cells (the intestinal enterochromaffin cell and the glicentin cell) are rare cells in the normal duodenal mucosa. The finding of these cells may indicate increased biological aggressivity.  相似文献   
103.
深圳市警察心理素质研究Ⅲ.心理健康与应对方式调查   总被引:28,自引:1,他引:28  
目的:探讨深圳警察的心理健康和应对方式及其与人口学特征的关系。方法:通过团体测试方式对6107名深圳警察进行症状自评量表(SCL-90)和简易应对方式问卷调查。结果:深圳警察SCL-90的总均分、阳性症状均分及l0个因子分均显著低于全国常模;其积极应对得分显著高于全国常模,而消极应对得分显著低于全国常模。深圳男性警察的躯体化、强迫、人际敏感、敌对、偏执、精神病及总均分均显著高于女性,其积极应对得分显著低于女性。36-40岁年龄段及副科级警察SCL-90多项因子分在各年龄段及各职务级别警察中得分最高;45岁以前,随着年龄的递增,积极应对和消极应对两维度的均分均相应递增。结论:年龄、性别、文化程度和职务级别的不同对深圳警察的心理健康状况和应对方式存在一定影响。积极应对有利于心理健康。  相似文献   
104.
目的:探讨不同时间睡眠剥夺(sleep deprivation,SD)对内隐记忆的影响。方法:将32名青年男性随机分为4组:对照组、SD21、SD45和SD69组,每组8名。采用补笔测验和组词测验对4组被试进行测试。结果:SD 后无论知觉启动还是语义启动,启动量降低,并随SD 时间延长而减少。同一组内,两种测验进行比较,除对照组外,其他SD 组两两比较,语义启动的启动量大于知觉启动(P<0.05)。知觉启动中,SD45同SD69 相比无显著差异(P=0.245),其他两两比较差异均有统计学意义(P<0.01);语义启动中,SD21同对照组相比差异无统计学意义(P=0.316),其他两两比较差异均有统计学意义(P<0.01)。结论:SD 后内隐记忆受损,并同SD 时间有关;SD 后语义启动和知觉启动出现分离,知觉启动更受SD 影响。  相似文献   
105.
高中生应对方式及其与学业成绩的关系   总被引:1,自引:0,他引:1  
目的:探讨高中生面对挫折和烦恼时应对方式的特点及其与学业成绩的关系。方法:以中学生应对方式评定问卷对649名高中生进行了调查。结果:女生比男生更倾向于采用发泄(因子均分2.4±0.7/2.7±0.7,F=23.32,P<0.01)和忍耐(3.2±0.7/3.0±0.8,F=5.08,P<0.05),而男生更倾向于采用幻想(2.4±0.9/2.1±0.8, F=15.52,P<0.01);重点中学比普通中学的高中生更多采用问题解决(3.3±0.6/3.1±0.7,F=20.85,P<0.011幻想(2.4±0.9/2.1±0.9,F=12.87,P<0.01)、退避(2.9±0.6/2.8±0.6,F=7.04,P<0.01)应对;来自城市和农村的高中生应对方式差异不显著;和睦安宁家庭气氛中的高中生采用问题解决应对显著多于偶尔争吵和经常争吵家庭中的高中生;民主型教养方式下的高中生比放任型教养方式的学生更多采用问题解决应对,权威型教养方式家庭中的高中生比民主型教养方式家庭中的高中生更多采用幻想应对。结论:高中生的应对方式存在性别差异。不同家庭气氛和不同教养方式以及学生在学业上的地位对应对方式也有一定影响,但城乡差别不明显。  相似文献   
106.
戴维斯在线认知问卷在538名医学生中的试用   总被引:1,自引:0,他引:1  
目的:建立戴维斯在线认知问卷中文版,并测试其信度和效度。方法:538名学生完成了戴维斯在线认知问卷,统计分析量表的信度和效度,并进行验证性因子分析。结果:戴维斯在线认知问卷中文版内部一致性系数为0.937,重测信度为0.905;验证性因子分析表明,各条目对4个一阶因子的标准负荷系数在0.423~0.814之间,4个一阶因子对上一级潜在因子的标准负荷系数在0.741~0.971之间;整体模式的适配度指标均符合心理测量学要求(RMSEA=0.012,GFI=0.943,NFI=0.931,CFI=0.994)。结论:戴维斯在线认知问卷中文版具有良好的信度和效度,可以作为一种较好的网络成瘾程度评价工具在我国青少年中使用。  相似文献   
107.
大学生网络成瘾类型问卷的初步编制   总被引:14,自引:2,他引:14  
目的:编制适用我国大学生的网络成瘾类型问卷。方法:根据访谈、开放式问卷施测结果,编制大学生网络成瘾类型问卷;调查样本为733名武汉地区大学生,91名大学生作为重测样本;检验了问卷的同质信度、重测信度、结构效度等。结果:探索性因素分析获得3个因素,即网络游戏成瘾、网络人际关系成瘾及网络信息成瘾,各因子负荷在0·50~0·82之间。总问卷及各分问卷的同质性信度(Cronbachα)、分半信度及重测信度分别为0·80~0·92、0·79~0·90和0·81~0·91。验证性因素分析结果表明问卷的三因素模型各项参数(RMSEA=0·07,CFI=0·98,NFI=0·97,IFI=0·98,TLI=0·97,RFI=0·96)均达到可以接受的水平。结论:该问卷具有较好的信度和效度,可用于大学生网络成瘾类型的测试。  相似文献   
108.
对Bem性别角色量表的考察与修订   总被引:20,自引:1,他引:20  
目的:对在性别角色研究中使用得最为广泛的工具-Bem量表进行介绍,考察它在中国文化下的信、效度并进行修订。方法:选取两个城市三所大学中的340名本科生为被试。经过项目分析、因素分析等统计方法,对构成量表的条目进行删除和保留。结果:最后由14项男性化条目和12项女性化条目构成新的Bem量表简本。结论:修订后的Bem量表在信、效度上有了明显的提高,可以成为进一步研究的工具。  相似文献   
109.
Context: Athletes in the United States are at high risk for using spit (smokeless) tobacco (ST) and incurring its associated adverse health effects.Objective: To examine whether an athletic trainer-directed ST intervention could decrease initiation and promote cessation of ST use among male collegiate baseball athletes.Design: Stratified, cluster-randomized controlled trial.Setting: Fifty-two California colleges.Patients or Other Participant(s): A total of 883 subjects in 27 intervention colleges and 702 subjects in 25 control colleges participated, as did 48 certified athletic trainers.Intervention(s): For college athletic trainers and associated dental professionals, a 3-hour video conference, and for collegiate athletes, an oral cancer screening with feedback and brief counseling during the preseason health screenings, athletic trainer support for cessation, and a peer-led educational baseball team meeting.Main Outcome Measure(s): The subjects' ST use over 1 year was assessed by self-report. At the end of the study, the certified athletic trainers were mailed a survey assessing their tobacco use and perceptions and behavior related to tobacco control in the athletic environment. We used multivariable logistic regression models for clustered responses (generalized estimating equations) to test the difference between groups in ST-use initiation and cessation and to identify significant overall predictors of noninitiation and cessation of ST use.Results: Of the 1585 athletes recruited, 1248 (78.7%) were followed up at 12 months. In addition, 48 of the 52 athletic trainers (92%) responded to the 1-year follow-up survey. The ST-use initiation (incidence) was 5.1% in intervention colleges and 8.4% in control colleges (generalized estimating equation odds ratio = 0.58, 95% confidence interval = 0.35-0.99). Predictors of ST noninitiation were low lifetime tobacco and monthly alcohol use (odds ratio = 1.98, 95% confidence interval = 1.40- 2.82) and athletic trainers' report that the baseball coach supported ST-use prevention activities (odds ratio = 1.43, 95% confidence interval = 1.11-1.83). Although at 1 year, cessation of ST use was relatively high in both groups (36%), we noted no significant difference between the groups (odd ratio = 0.94, 95% confidence interval = 0.70-1.27).Conclusions: The intervention was significantly effective in preventing incident ST use but did not significantly increase cessation beyond that seen in the control group. The latter finding is inconsistent with previous studies and may be explained by spillover of the intervention to control colleges, other anti-tobacco activity in control colleges, and/or the small sample of dependent ST users enrolled in the study.  相似文献   
110.
The Oka vaccine strains of varicella-zoster virus (VZV) have a significantly different BgII DNA restriction pattern from that of American wild-type isolates of VZV. This difference consists primarily of an additional BgII site, which lies within the BamHI "D" fragment. In conjunction with a study of the efficacy of an experimental Merck/Oka VZV vaccine, the area of the genome from which the most marked restriction pattern alteration arises was studied more closely to determine if there are other significant differences between the Oka strains and American wild-type strains. BamHI "D" fragments from the DNA of the Oka parent strain (the progenitor of the vaccine strain), the RIT/Oka vaccine strain (a derivative of the Oka parent strain), the Merck/Oka vaccine strain, and the EF strain (an American wild type), were submitted to extensive endonuclease digestion studies to ascertain if additional unique restriction sites are present in the Oka parent or vaccine strains. The extra BgII restriction site characteristic of the Merck/Oka vaccine strain is also present in the DNA of the parent virus as well as its derivatives and was therefore not produced by the "attenuation" process. No other novel sites were found in the Oka parent or Oka-derived strains in this section of the genome. The Merck/Oka vaccine strain of VZV, despite its Japanese origin, is therefore quite similar to circulating American varicella-zoster virus strains. Varicella-zoster virus DNA, at least in the area of the BamHI D fragment, also appears to be remarkably stable from strain to strain.  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