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   7283篇
  免费   432篇
  国内免费   215篇
耳鼻咽喉   73篇
儿科学   67篇
妇产科学   44篇
基础医学   1547篇
口腔科学   391篇
临床医学   533篇
内科学   829篇
皮肤病学   74篇
神经病学   1011篇
特种医学   415篇
外国民族医学   1篇
外科学   610篇
综合类   920篇
预防医学   472篇
眼科学   55篇
药学   395篇
中国医学   148篇
肿瘤学   345篇
  2024年   6篇
  2023年   92篇
  2022年   181篇
  2021年   224篇
  2020年   200篇
  2019年   207篇
  2018年   225篇
  2017年   195篇
  2016年   208篇
  2015年   205篇
  2014年   434篇
  2013年   445篇
  2012年   374篇
  2011年   470篇
  2010年   380篇
  2009年   370篇
  2008年   353篇
  2007年   376篇
  2006年   326篇
  2005年   295篇
  2004年   272篇
  2003年   227篇
  2002年   194篇
  2001年   178篇
  2000年   147篇
  1999年   133篇
  1998年   142篇
  1997年   139篇
  1996年   116篇
  1995年   117篇
  1994年   88篇
  1993年   76篇
  1992年   74篇
  1991年   51篇
  1990年   48篇
  1989年   47篇
  1988年   39篇
  1987年   29篇
  1986年   34篇
  1985年   53篇
  1984年   28篇
  1983年   37篇
  1982年   17篇
  1981年   27篇
  1980年   16篇
  1979年   10篇
  1978年   5篇
  1977年   6篇
  1976年   8篇
  1972年   2篇
排序方式: 共有7930条查询结果,搜索用时 15 毫秒
11.
Solitary fibrous tumors (SFT) have recently been established to be of mesenchymal origin. Although there are numerous reports of SFTs arising from the pleura, reports of the tumor arising from extrapleural sites are comparatively rare [Fletcher CDM, Unni K, Mertens F (eds) World Health Organization classification of tumors, pathology & genetics, tumors of soft tissue and bone. IARC Press, Lyon, pp 86–901, 2002]. We report a case of SFT arising in the inguinal region.  相似文献   
12.
在35例有L5和/或S1神经根损害表现的腰椎间盘突出患者腰椎区进行磁刺激运动诱发电位(MEP)检查,测定、记录胫前肌、展肌和小趾展肌MEP的起始潜伏期(OL)。结果显示,35例中至少有一条总侧肌肉MEP异常33例(94.3%)。在L4-5椎间盘突出中,以胫前肌的MEP异常为主;在L5-S1椎间盘突出中,以小趾展肌的MEP异常为主。表明腰椎区MEP检查对腰椎间盘突出所致的腰骶神经根病变较为敏感,可为临床诊断提供可靠依据并有助于定位诊断。  相似文献   
13.
中国部分地区妇幼卫生信息系统的现状分析   总被引:3,自引:1,他引:2  
王燕  石玲  安琳 《中国妇幼保健》2003,18(9):516-518
本文通过研究卫生 项目地区报表资料和现场调查 ,对项目地区妇幼卫生信息系统的建设及运作情况进行了分析 ,并对报表数据质量进行了评价。分析显示 :卫 项目推动了贫困地区信息系统建设 ,项目地区已建立起系统的妇幼卫生信息管理体系 ,但分析也反映出项目地区妇幼卫生常规报表的数据质量仍存在一定问题。分析结果提示 ,应进一步加强妇幼卫生信息系统建设 ,提高妇幼卫生统计信息专业队伍的业务水平。  相似文献   
14.
为了探讨腰神经通道狭窄的病因,我们对224例腰椎间盘突出及腰椎管狭窄症患者进行了腰神经通道探查手术,结果发现其病因以腰部组织变性为主。除外伤及反复慢性腰部损伤引起腰部病变外,活动少,或很少进行腰部锻炼,体形肥胖也是引起腰神经通道狭窄日趋加重的致病因素。在治疗时强调不只满足于切除突出的椎间盘,应沿神经通道探查,清除一切卡压神经根的病变组织才能获得较好的治疗效果。我们随访197例,平均随访3a,优良率935%。  相似文献   
15.
The expressed human κ light chain gene repertoire utilized by healthy individuals was studied by two different single-sided specific PCR techniques to avoid bias for certain V genes. A total of 103 rearranged κ sequences from peripheral blood mononuclear cells from healthy individuals were cloned from cDNA and assigned to the Vκ and Jκ germ-line genes with the closest overall homology. The use of cDNA rather than genomic DNA focused the analysis on activated B cells rich in mRNA. Accordingly, the sequences represented the applied repertoire and almost all were somatically mutated. V genes from the Jκ-proximal duplication unit of the κ locus were almost exclusively used. A total of 65% of the sequences could be assigned to four or five genes: A27 (humkv325), L6 (Vg), L2 (humkv328), and A3 and/or A19. N additions and P nucleotides were quite common and found in 32% and 21% of the sequences, respectively. Extended CDR3s more than nine residues in length were found in 18% of the sequences, and in 71% of cases this was due to insertion of an extra proline residue. This proline was usually explained from the germ-line sequences involved. These results are in good agreement with those of previous repertoire studies using potentially V-gene-biased techniques. Thus, it is clear that restricted V-gene usage, common N and P additions, and extended CDR3 regions are normal features and not, as has been claimed, characteristics of pathological autoantibodies.  相似文献   
16.
神经导航辅助显微手术治疗脑功能区肿瘤   总被引:6,自引:2,他引:4  
目的探讨神经导航系统辅助下脑重要功能区肿瘤显微手术的治疗效果和应用价值。方法1999年12月~2002年6月应用StealthStation神经导航系统辅助切除邻近脑重要功能区肿瘤10例,对神经导航系统术中应用的优越性、精确性等进行分析。结果本组平均注册误差为(2.8±0.9)mm,肿瘤和重要解剖功能结构定位准确,肿瘤全切除率77.8%。术后神经功能未受明显影响,无手术并发症及死亡。结论神经导航系统对于切除邻近脑重要功能区肿瘤具有定位准确,动态示踪和实时导航,侵袭性小,安全、可靠等特点,有助于提高肿瘤全切率及降低手术并发症。  相似文献   
17.
18.
We describe the case of a young male patient, SN, who suffered a MR-documented ischaemic lesion of both dorsomedial thalami and presented with a transient maniform syndrome. SN's neuropsychological, structural and functional imaging findings are compared with similar reported cases and are discussed in the framework of fronto-subcortical circuits and their proposed behavioural disorders. SN's mania was characterized by restlessness, mood elevation, a tendency for pleasurable activities, inflated self-esteem and loss of disease awareness. Other symptoms were sexual disinhibition, tactlessness, abnormal discourse, and reduced need for food and sleep. His neuropsychological assessment revealed an anterograde amnesia, and an impairment of frontal-executive functions. A SPECT-study showed diaschisis-related areas of hypoperfusion in both prefrontal regions which were interpreted as equivalents of SN's frontal-dysexecutive syndrome. In addition, there was a perfusion deficit in the right orbitofrontal cortex, which was taken as the imaging correlate of SN's secondary mania and personality disorder. These findings suggest that SN's mania and his other symptoms result from the twofold disruption of fronto-subcortical connections, namely of the right orbitofrontal loop which is concerned with mood regulation and socially appropriate behaviour, and of the dorsolateral prefrontal loop which mediates executive cognitive functions.  相似文献   
19.
金银花nrDNA ITS区聚合酶链反应条件的研究   总被引:1,自引:0,他引:1       下载免费PDF全文
目的:金银花nrDNA ITS区序列G C含量为68%,用常规的PCR方法扩增效果差.本研究通过改变扩增程序及使用改性剂的方法显著提高了金银花nrDNA ITS区的扩增效率.方法:分别从金银花叶及药材中提取总DNA,通过优化扩增条件,对nrDNA ITS区进行扩增,并比较了两种优化方法的差别及适应性.方法1:提高变性温度至97℃;方法2:添加混合改性剂(DMSO 4%-甘油10%).结果:与方法1相比,方法2可降低变性温度5 ℃,升高退火温度9 ℃,降低镁离子浓度至0.5 mmol/L,降低Taq DNA聚合酶用量至0.1 U(30 μl体系),PCR产物量显著提高,且可消除植物DNA粗提物中杂质的干扰.结论:通过提高退火温度及添加改性剂可克服高G C含量金银花nrDNA ITS区序列扩增的困难,该方法的建立有助于解决植物来源DNA模板的PCR扩增问题.  相似文献   
20.
Recently the term 'global aging', which refers to the universal trend of aging of the world population, is being widely used. First of all, I will shed some light on this trend of world population aging from the viewpoint of regional populations and their future projections.
Second, I will discuss about the determinants of population aging in the Asia and Oceania region. So far as the region is concerned, it will be divided into three groups of countries according to the level of population aging. The first group is the most advanced aged countries such as Japan, Australia, and New Zealand whose percentage of the elderly aged 65 and over is more than 10% in the year of 2000. The second group is the aging countries such as Korea, Taiwan, Singapore, and China whose percentage of the elderly is between 5 and 10%. and the third group is the remaining countries in this region whose percentage is less than 5%. The demographic aspects of each group are analyzed and the relationships between the fertility reduction and aging are also discussed in the perspectives of the demographic transition.
Third, I will discuss about the consequences of population aging in this region with special reference to Asian developing countries. In this section, I will mention the problems of dependency burden, the so-called population bonus, health expectancy, and social security systems. Fourth, some prominent characteristics concerning the living conditions and norms or attitudes of the elderly will be indicated, and I will also raise such points like family systems, living arrangements, social participation, and Ikigai (the worth of life) peculiar to Asian countries. Fifth and finally, I will touch on the topics of the issues and policies of the aging society. At present the social status of the elderly is improving in Asian countries and it is in the hope that the myth of aging will disappear in the near future.  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