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   14529篇
  免费   1859篇
  国内免费   304篇
耳鼻咽喉   55篇
儿科学   176篇
妇产科学   111篇
基础医学   1380篇
口腔科学   198篇
临床医学   1247篇
内科学   1275篇
皮肤病学   81篇
神经病学   967篇
特种医学   638篇
外科学   928篇
综合类   2423篇
现状与发展   1篇
一般理论   8篇
预防医学   4063篇
眼科学   150篇
药学   1577篇
  10篇
中国医学   872篇
肿瘤学   532篇
  2024年   91篇
  2023年   429篇
  2022年   732篇
  2021年   1010篇
  2020年   925篇
  2019年   741篇
  2018年   645篇
  2017年   710篇
  2016年   663篇
  2015年   601篇
  2014年   1017篇
  2013年   1151篇
  2012年   722篇
  2011年   860篇
  2010年   648篇
  2009年   595篇
  2008年   642篇
  2007年   627篇
  2006年   571篇
  2005年   495篇
  2004年   431篇
  2003年   381篇
  2002年   300篇
  2001年   224篇
  2000年   163篇
  1999年   127篇
  1998年   125篇
  1997年   134篇
  1996年   84篇
  1995年   80篇
  1994年   91篇
  1993年   73篇
  1992年   62篇
  1991年   60篇
  1990年   53篇
  1989年   61篇
  1988年   46篇
  1987年   54篇
  1986年   40篇
  1985年   33篇
  1984年   32篇
  1983年   24篇
  1982年   33篇
  1981年   16篇
  1980年   27篇
  1979年   10篇
  1978年   9篇
  1977年   8篇
  1976年   11篇
  1974年   7篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
91.
脑电(Electroencephalography, EEG)和功能磁共振(Functional magnetic resonance imaging, fMRI)技术的结合,可以实现两者优势的互补,获得更加合理的源定位结果.本文报道的是一种将fMRI先验信息结合到脑电源定位中的新方法.在该方法中,先利用SPM方法计算获得fMRI的统计映射参数,然后将基于计算获得的统计参数构造的权矩阵结合到FOCUSS的迭代过程中,对脑电的反演提供具有fMRI先验空间位置信息的约束,提高脑电的源空间定位精度,从而获得更加合理的定位结果.通过对一形状知觉实验fMRI和脑电数据的结合定位分析,结果初步证实了改进方法能获得和生理更加一致的结果.  相似文献   
92.
鉴于常见的动态绘制肌电曲线时出现的屏幕闪烁和抖动问题 ,设计了在面向对象的VisualC 6 .0开发平台上 ,利用MFC(MicrosoftFoundationClasses)类库中的位图类CBitmap来绘制肌电曲线图像 ,解决肌电数据的动态回放和实时监测中的屏幕闪烁和抖动问题  相似文献   
93.
Heritability coefficients are offered for four personality source traits, measured by the O-A (objective-analytic) 2-h performance battery. Five family constellations covering a total sample of 1221 boys 12–18 years old yielded nine concrete variances which the MAVA (multiple abstract variance analysis) model resolves into seven abstract variances: 2 wg , within family genetic; 2 wt.s , within family threptic; 2 wt.t , within family threptic for twins; 2 bg , between family genetic; bgbt , correlation of genetic and threptic deviations across families, etc. Maximum likelihood was the method here used for the MAVA analysis. The best fit with maximum parsimony was to assume no genothreptic ( wgwt , bgbt ) correlations, but extension to the parsimony of assuming either no genetic or no threptic components gave no fit. The heritabilities found were compared with those from an earlier research and from a different (OSES) method applied to the present data. The agreement is quite good in assigning a moderate heritability value tocapacity to mobilize vs. regression, U.I.23 (H about 0.30), and toanxiety, U.I.24 (H about 0.50); only moderately consistent in assigning a moderateH value toasthenia, U.I.28 (H about 0.30); and poorly consistent in assigning a lowH value tonarcistic ego, U.I.26. It is pointed out (a) that the lowH for U.I.28 fits the theory of the origin of this trait well and (b) that, in view of estimates of the function fluctuation of U.I.23 and 24, a most probable conclusion is that a capacity to mobilize is quitesubstantially innate and a general proneness to anxiety islargely innate.  相似文献   
94.
The “Biotype-100” identification system (BioMérieux, La Balme-les-Grottes, France) based on carbon source utilization was evaluated for its ability to discriminate among 10 species of Rhodococcus, 7 species of Gordona and one species of Dietzia. The type strains of three species of Tsukamurella and 8 species of Nocardia were also included in the study. Results were compared with chemotaxonomic and conventional data. Carbon source utilization was shown to be reliable, rapid and easy to use when compared with standard identification methods. The 29 species tested were unambiguously separated by carbon source utilization tests. Rhodococcus equi was found to be heterogenous.Les galeries “Biotype-100” (BioMérieux) ont été utilisées pour différencier 10 espèces du genre Rhodococcus, 7 espèces du genre Gordona et 1 espèce du genre Dietzia entre elles. Les souchestypes de 3 espèces du genre Tsukamurella et 8 espèces du genre Nocardia ont été incluses dans cette étude. Les résultats ont été comparés avec ceux des études chimiotaxonomiques et ceux obtenus avec les galeries d'identification classiques. Les galeries Biotype-100 sont sûres, rapides et faciles à utiliser par rapport aux galeries classiques. Les 29 espèces étudiées ont été identifiées sans aucune difficulté. L'espèce Rhodococcus equi s'est révélée hétérogène.  相似文献   
95.
96.
This study evaluated the migration to full-PACS of medical image data archived using mini-PACS at two hospitals of the Yonsei University Medical Center, Seoul, Korea. A major concern in the migration of medical data is to match the image data from the mini-PACS with the hospital OCS (Ordered Communication System). Prior to carrying out the actual migration process, the principles, methods, and anticipated results for the migration with respect to both cost and effectiveness were evaluated. Migration gateway workstations were established and a migration software tool was developed. The actual migration process was performed based on the results of several migration simulations. Our conclusions were that a migration plan should be carefully prepared and tailored to the individual hospital environment because the server system, archive media, network, OCS, and policy for data management may be unique.  相似文献   
97.
在颈椎生物力学研究中,通过离体实验对颈椎内植入固定器的生物力学性能进行评价是国际上普遍采用并认可的方法.本研究利用多靶点三维运动跟踪系统和USB数据采集卡,以LabVIEW和Matlab为软件开发平台,构建了颈椎内植入固定器生物力学性能测试系统.测试参数包括三维运动角度范围(ROM)和压力载荷值.对颈椎模型的测试结果表明,本系统能有效地用于颈椎生物力学的离体实验测试.  相似文献   
98.
Three different auditory stimulus paradigms were used to elicit P300 potentials. Normal subjects were tested on the classical rare target stimulus, single-stimulus and omitted-stimulus conditions. Noninvasive identification of the cerebral sources of the event-related potentials (ERPs) was performed using spatio-temporal multiple dipole modeling (BESA software) with individually sized spherical head models. The grand average data of each condition was first independently modeled and these models were used as starting values for modeling each individual subject's data. Models for the rare-stimulus condition and single-stimulus condition both consisted of 6 dipoles. Models for the omitted-stimulus condition consisted of 2 dipoles. The dipole locations of the final individual 6-dipole models for the rare and single-stimulus conditions did not differ significantly from each other or from one previous result obtained from a another group of subjects (Tarkka et al. 1995). Super-imposition of the dipole coordinates on the sterotaxic brain atlas suggests that bilateral deep medial temporal lobe structures are the major contributors to rare and single-stimulus P300s. Because both the wave form morphology and the source model of the P300 elicited by single stimulus were close to those of the rare-stimulus P300 it may be that the underlying neural mechanisms eliciting these P300 potentials are essentially the same.  相似文献   
99.
A brief introduction to the Danish Cytogenetic Central Register (DCCR) is given, and possibilities, principles and problems concerning the establishment and maintenance of a national cytogenetic register are presented.
Various data carrier media for registers in general are discussed, of which the magnetic disc is considered most appropriate. General principles for programs capable of performing insertions, deletions and other modifications in the data base are outlined as well as the principles for the programs in the DCCR.
The individual records should preferably be identified by aid of a central person registration number (CPR) rather than by name. The data should be stored and sorted by this identification in order to facilitate retrieval of a desired record. The structure of the records is discussed with regard to prevention of the occurrence of certain errors as well as the optimization of processing.
Flexibility and economy of space are achieved by using programs able to handle records of unequal length, and problems occurring in connection with this are discussed. The question of how to protect sensitive data is dealt with, and two different methods used in the DCCR are outlined. Programs capable of analyzing karyotypes with the purpose of recognizing various cytogenetic syndromes have been developed for use in the DCCR. Various examples of computing times of typical program runs are presented.  相似文献   
100.
We undertook a theoretical analysis of the source resistance of the left ventricle represented in a mean pressure-mean flow diagram, using the chamber properties established in terms of the pressure-volume relationship. This analysis showed that pairs of points should lie above the linear function proposed by Elzinga and Westerhof. A third-order polynomial function would theoretically explain better than a linear relation or a parabolic fit the curved shape of experimentally obtained relationships. The analysis resolves the discrepancy between Elzinga and Westerhof's theoretical concept of linear source resistance and the actual nonlinear relationship.  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