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   14454篇
  免费   1800篇
  国内免费   296篇
耳鼻咽喉   58篇
儿科学   157篇
妇产科学   120篇
基础医学   1301篇
口腔科学   194篇
临床医学   1282篇
内科学   1308篇
皮肤病学   112篇
神经病学   751篇
特种医学   537篇
外科学   1002篇
综合类   2342篇
现状与发展   2篇
一般理论   8篇
预防医学   3935篇
眼科学   269篇
药学   1694篇
  8篇
中国医学   917篇
肿瘤学   553篇
  2024年   87篇
  2023年   470篇
  2022年   724篇
  2021年   1060篇
  2020年   932篇
  2019年   808篇
  2018年   703篇
  2017年   723篇
  2016年   647篇
  2015年   603篇
  2014年   1045篇
  2013年   1169篇
  2012年   690篇
  2011年   803篇
  2010年   605篇
  2009年   549篇
  2008年   614篇
  2007年   609篇
  2006年   564篇
  2005年   458篇
  2004年   405篇
  2003年   348篇
  2002年   277篇
  2001年   190篇
  2000年   142篇
  1999年   114篇
  1998年   117篇
  1997年   112篇
  1996年   80篇
  1995年   68篇
  1994年   82篇
  1993年   68篇
  1992年   60篇
  1991年   58篇
  1990年   50篇
  1989年   61篇
  1988年   45篇
  1987年   53篇
  1986年   40篇
  1985年   48篇
  1984年   44篇
  1983年   33篇
  1982年   42篇
  1981年   25篇
  1980年   39篇
  1979年   15篇
  1978年   13篇
  1977年   13篇
  1976年   15篇
  1974年   8篇
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
41.
This paper presents the use of iterative dynamic programming employing exact penalty functions for minimum energy control problems. We show that exact continuously non-differentiable penalty functions are superior to continuously differentiable penalty functions in terms of satisfying final state constraints. We also demonstrate that the choice of an appropriate penalty function factor depends on the relative size of the time delay with respect to the final time and on the expected value of the energy consumption. A quadratic approximation (QA) of the delayed variables is much better than a linear approximation (LA) of the same for relatively large time delays. The QA improves the rate of convergence and avoids the formation of ‘kinks‘. A more general way of selecting appropriate penalty function factors is given and the results obtained using four illustrative examples of varying complexity corroborate the efficacy of the method.  相似文献   
42.
A total of 103 fragments in the STR D12S391 locus were sequenced. 24 different alleles were found which can be grouped into 12 allelic classes based on the total number of repeats. The structure of this compund STR consists of blocks of (AGAT) and (AGAC) repeats with a consensus structure (AGAT)8–l7 (AGAC)6–10 (AGAT)0–1. Whereas shorter alleles only have (AGAT) repeats, > 225 bp alleles are more complex, having two motifs (AGAT) and (AGAC). Population data showed that this to be a highly polymorphic STR with a heterozygosity of 0.9. This fact together with its simple structure make this STR very suitable for forensic and genetic purposes.  相似文献   
43.
刘广勇 《医疗设备信息》2007,22(11):114-115
分析了GELOGIQ 400B超机不能启动的故障,经对电源、主板、硬盘的维修,机器恢复正常。  相似文献   
44.
45.
论“恐伤”心理的基因定势表达   总被引:3,自引:0,他引:3  
本文在基因定势表达研究概况基础上,列举0MIM上部分与恐惧等心理因素定势的基因与疾病,进而探讨心理、基因定势表达与精神病的关系。  相似文献   
46.
目的 近年来产生了一些用于分析基因表达数据的聚类算法,却很少有关于评价聚类算法方法的研究。本研究的目的是尝试建立一个定量的评价基因表达数据聚类结果的方法。方法 本研究提供了一个系统的评价聚类结果的方法,利用我们提出的实验均方误差F值对几个常见的聚类算法进行比较。结果 利用F值对类质量的评价和利用已有的生物学知识对类进行分析的结果一致。结论 实验均方误差F值可以定量地评判用于基因表达数据的聚类算法。  相似文献   
47.
    
A knowledge-based alarm system for intensive care monitoring was designed, built, tested on-line, and evaluated. The system is a functional prototype of a highly specific patient monitor providing alarms on hypovolemia, hyperdynamic state, left ventricular failure and hypoventilation. These intelligent alarm functions aim to maintain the quality of patient monitoring even if nurses' attention is temporarily reduced or focused elsewhere. The alarm system has an electronic access to data available in a multichannel patient monitor and the patient data management system of the intensive care unit. Median filtering, trend estimation, and rule-based reasoning are applied when processing the measured variables and estimating the patient's state.  相似文献   
48.
Two programs have been developed to manage linkage analysis data. The first program, LABMAN, is a comprehensive laboratory data management system organizing pedigrees, blood DNA samples, DNA markers, Southern blot or polyacrylamide gels, autoradiographs, and marker-allele typings generated from these samples. Output includes mendelization checks for genetic incompatibilities in typings and formatted files ready for linkage analysis. LABMAN can also compress highly polymorphic allele systems into smaller allele systems facilitating analysis of large systems. The second program, LINKMAN, provides data management for lod score output from linkage analyses. It reads linkage analysis output files, calculates lod scores by family, associates lod scores with specific marker and family identifiers, and stores these data in a database where they can be combined with lod scores from previous analyses. LINKMAN easily incorporates any of a wide variety of genetic models. It produces formatted output of lod scores by user-specified criteria for reports or as ASCII files for input to other programs. If desired, tests of homogeneity of linkage across families can be run via the HOMOG program [Ott, 1991] and their output included in reports. The programs include features critical for conducting genome searches of complex diseases: They are easy-to-use, well-tested, and reliable. Data from multi-center investigations can be easily combined for analysis. Moreover, they include extensive error-checking capabilities, and they are specifically set up to protect blindness between laboratory workers and data analysts. LABMAN and LINKMAN are currently available free of charge under DOS. © 1994 Wiley-Liss, Inc.  相似文献   
49.
The F.I.P. (Financial Information Project) dietetic package allows the collection of basic patient data, which then can be processed to give valuable clinical and management information for use by all dietitians in a dietetic department. The advent of the Korner Reports (DHSS, 1984a) and their implementation highlighted the need to computerize certain aspects of data collection in dietetic departments. Within the West Midlands Regional Health Authority a group of dietitians worked with the Regional Management Services Department to adapt a community nursing system, F.I.P., for use by dietitians. The system was piloted for all paramedical services in 1987 with one health district (North Warwickshire) piloting the dietetic package. It is now used by a range of dietetic and paramedical departments. This paper outlines the system and its uses.  相似文献   
50.
老年髋部骨折术后患者康复需求程度与康复状况调查   总被引:2,自引:0,他引:2  
目的了解老年髋部骨折术后患者康复需求程度、需求满足度与康复状况的关系.方法上门随访82例老年髋部骨折术后患者家庭康复现状和康复需求情况.结果康复需求10个维度中他人支持、康复信息及功能训练指导位居前3位;需求程度与生理功能、躯体功能和社会功能有关(P<0.05,P<0.01);与髋关节功能评分中的疼痛程度、上楼梯、穿鞋袜和行走距离4个方面有关(P<0.05,P<0.01).结论出院后定期给予针对性的康复训练指导和健康教育是患者迫切的需求;康复需求程度高者,相应需求满足率低,其生活质量及髋关节功能恢复应成为干预的重点.  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