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   1554篇
  免费   173篇
  国内免费   42篇
耳鼻咽喉   13篇
儿科学   24篇
妇产科学   15篇
基础医学   179篇
口腔科学   75篇
临床医学   153篇
内科学   206篇
皮肤病学   7篇
神经病学   111篇
特种医学   73篇
外国民族医学   1篇
外科学   222篇
综合类   141篇
预防医学   244篇
眼科学   37篇
药学   112篇
中国医学   41篇
肿瘤学   115篇
  2024年   16篇
  2023年   83篇
  2022年   107篇
  2021年   164篇
  2020年   107篇
  2019年   107篇
  2018年   90篇
  2017年   70篇
  2016年   46篇
  2015年   57篇
  2014年   83篇
  2013年   119篇
  2012年   63篇
  2011年   65篇
  2010年   42篇
  2009年   80篇
  2008年   61篇
  2007年   49篇
  2006年   45篇
  2005年   36篇
  2004年   41篇
  2003年   33篇
  2002年   31篇
  2001年   20篇
  2000年   14篇
  1999年   9篇
  1998年   17篇
  1997年   13篇
  1996年   16篇
  1995年   10篇
  1994年   14篇
  1993年   3篇
  1992年   12篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   5篇
  1987年   2篇
  1986年   2篇
  1985年   7篇
  1984年   4篇
  1983年   6篇
  1982年   1篇
  1981年   5篇
  1980年   2篇
  1979年   2篇
  1977年   2篇
排序方式: 共有1769条查询结果,搜索用时 15 毫秒
101.
The Self‐Attention Network (SAN) has been proposed to describe the underlying neural mechanism of the self‐prioritization effect, yet the roles of the key nodes in the SAN—the left posterior superior temporal sulcus (LpSTS) and the dorsolateral prefrontal cortex (DLPFC)—still need to be clarified. One hundred and nine participants were randomly assigned into the LpSTS group, the DLPFC group, or the sham group. We used the transcranial magnetic stimulation (TMS) technique to selectively disrupt the functions of the corresponding targeted region, and observed its impacts on self‐prioritization effect based on the difference between the performance of the self‐matching task before and after the targeted stimulation. We analyzed both model‐free performance measures and HDDM‐based performance measures for the self‐matching task. The results showed that the inhibition of LpSTS could lead to reduced performance in processing self‐related stimuli, which establishes a causal role for the LpSTS in self‐related processing and provide direct evidence to support the SAN framework. However, the results of the DLPFC group from HDDM analysis were distinct from the results based on response efficiency. Our investigation further the understanding of the differentiated roles of key nodes in the SAN in supporting the self‐salience in information processing.  相似文献   
102.
Little is known about the neural correlates of lower limbs position sense, despite the impact that proprioceptive deficits have on everyday life activities, such as posture and gait control. We used fMRI to investigate in 30 healthy right‐handed and right‐footed subjects the regional distribution of brain activity during position matching tasks performed with the right dominant and the left nondominant foot. Along with the brain activation, we assessed the performance during both ipsilateral and contralateral matching tasks. Subjects had lower errors when matching was performed by the left nondominant foot. The fMRI analysis suggested that the significant regions responsible for position sense are in the right parietal and frontal cortex, providing a first characterization of the neural correlates of foot position matching.  相似文献   
103.
Research in the field of mental health consequences of abortion is characterized by methodological limitations. We used exact matching on carefully selected confounders in a prospective cohort study of 325 women who had an abortion of an unwanted pregnancy and compared them 1-to-1 to controls who did not have this experience. Outcome measures were incidence and recurrence of common DSM-IV mental disorders (mood, anxiety, substance use disorders, and the aggregate measure ‘any mental disorder’) as measured with the Composite International Diagnostic Interview (CIDI) version 3.0, in the 2.5–3 years after the abortion. Although non-matched data suggested otherwise, women in the abortion group did not show significantly higher odds for incidence of ‘any mental disorder’, or mood, anxiety and substance use disorders, compared to matched controls who were similar in background variables but did not have an this experience. Having an abortion did not increase the odds for recurrence of the three disorder categories, but for any mental disorder the higher odds in the abortion group remained significant after matching. It is unlikely that termination of an unwanted pregnancy increases the risk on incidence of common mental disorders in women without a psychiatric history. However, it might increase the risk of recurrence among women with a history of mental disorders.  相似文献   
104.
We compared matches between colours that were both presented on a computer monitor or both as pieces of paper, with matching the colour of a piece of paper with a colour presented on a computer monitor and vice versa. Performance was specifically poor when setting an image on a computer monitor to match the colour of a piece of paper. This cannot be due to any of the individual judgments because subjects readily selected a matching piece of paper to match another piece of paper and set the image on the monitor to match another image on a monitor. We propose that matching the light reaching the eye and matching surface reflectance are fundamentally different judgments and that subjects can sometimes but not always choose which to match.  相似文献   
105.
目的:应用Rh血型抗原鉴定,对Rh阴性患者中存在不规则抗体的输血患者选择相合性输注。方法:对2007年1月-2008年12月检出的RhD阴性输血患者进行D抗原复检、抗体筛查,及对其他Rh血型抗原进行鉴定。结果:在79例RhD阴性的输血患者中抗体筛查阳性的共25例;抗-D抗体3例,抗-E8例,抗-c4例,抗-c、E7例,抗-C1例,抗-e3例,对存在不规则抗体的患者均选择Rh因子相合的血液输注,其中,有7例患者采用O型的ccdEE和CCdee表型红细胞输注。结论:应用抗体筛查及Rh抗原鉴定的结果,选择Rh因子相合的血液输注及对有抗c和抗e抗体的阴性患者在血源困难的情况下选择O型的ccdEE和CCdee表型红细胞输注,保证了特殊血型的用血需求,既可以避免不规则抗体的产生,同时也减少了输血不良反应的发生。  相似文献   
106.
目的旨在探讨Vitapan Classical比色板和Vitapan3D-Master比色板在口腔修复科临床中的比色效果,以指导临床工作。方法采用修复前比色、修复体制作完成后口腔外比色以及口腔内核对颜色的方法,对比两种比色板的比色效果。结果修复体制作完成后,在口腔内、外核对颜色时,使用Vitapan3D-Master比色板的满意度高于Vitapan Classical比色板(P<0.05)。结论Vitapan3D-Master比色板颜色范围较宽,临床比色可以取得较好的效果。  相似文献   
107.
In addition to their deficit in overt face recognition, patients with prosopagnosia also have difficulties in matching sequentially presented unfamiliar faces. Here we assessed the possibility that covert matching of faces was present in a case with prosopagnosia using event-related potentials (ERPs). The participants (patient FE and normal controls) were challenged with a face-identity matching task, in which they decided whether two sequentially presented photographs of unfamiliar faces represented the same person. Only internal face features were used and the two faces in a pair differed in emotional expression. FE failed to overtly match these stimuli. In contrast, the ERPs revealed evidence of covert matching. If the two faces within a pair of stimuli depicted different posers, then the response to the second face contained an enhanced N300 compared to the situation where the identity of the faces was the same. The latency of the N300 was the same as a similar component found in controls. These results suggest that some cases with prosopagnosia have a covert ability to match unfamiliar faces, with similar temporal dynamics as controls, which in contrast with the idea that a generalized slowing of face processing occurs in all cases of prosopagnosia.  相似文献   
108.
We studied the influence of HLA mismatches on T lymphocyte cultures that were derived from endomyocardial biopsies (EMB) from 118 heart transplant recipients. From patients with DR mismatches, the majority of the EMB-derived cultures were dominated by CD4, while in patients without DR mismatches, CD8 was the predominant T cell subset. The majority (75) of the cultures were cytotoxic against donor antigens. A significantly (P < 0.005) lower proportion of the cultures showed cytotoxicity (36 %) against HLA-A antigens when compared to HLA-B (53 %) or HLA-DR (49 %). A dose effect phenomenon was detected for all HLA antigens, including HLA-A: a higher number of A, B or DR mismatches resulted in a higher number of cytotoxic cultures directed against these antigens. B and DR matching had the greatest influence on 6 month freedom from rejection. Both our experimental and clinical data indicated that HLA matching played a role in the immune response against a transplanted heart.  相似文献   
109.
We present in this paper a connectionist model that extracts interaural intensity differences (IID) from head-related transfer functions (HRTF) in the form of spectral cues to localize broadband high-frequency auditory stimuli, in both azimuth and elevation. A novel discriminative matching measure (DMM) is defined and optimized to characterize matching this IID spectrum. The optimal DMM approach and a novel backpropagation-based fuzzy model of localization are shown to be capable of localizing sources in azimuth, using only spectral IID cues. The fuzzy neural network model is extended to include localization in elevation. The use of training data with additive noise provides robustness to input errors. Outputs are modeled as two-dimensional Gaussians that act as membership functions for the fuzzy sets of sound locations. Error back-propagation is used to train the network to correlate input patterns and the desired output patterns. The fuzzy outputs are used to estimate the location of the source by detecting Gaussians using the max-energy paradigm. The proposed model shows that HRTF-based spectral IID patterns can provide sufficient information for extracting localization cues using a connectionist paradigm. Successful recognition in the presence of additive noise in the inputs indicates that the computational framework of this model is robust to errors made in estimating the IID patterns. The localization errors for such noisy patterns at various elevations and azimuths are compared and found to be within limits of localization blurs observed in humans.  相似文献   
110.
Group randomized trials (GRT) are often designed with relatively little preliminary data available to estimate key parameters. In this paper, however, the opposite situation is considered-very good baseline data are available on the primary outcome of interest. These data can then be used to inform key design and analysis decisions such as (i) should the trial be designed as an unmatched or pair-matched study, or stratified in some other fashion; (ii) is analysis of "change from baseline" preferable to using end-of-study data alone; and (iii) what power might be expected by pursuing these various strategies. The results are applied to a GRT for sexually transmitted diseases prevention in Peru.  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