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   4074篇
  免费   293篇
  国内免费   37篇
耳鼻咽喉   46篇
儿科学   78篇
妇产科学   81篇
基础医学   570篇
口腔科学   67篇
临床医学   376篇
内科学   941篇
皮肤病学   82篇
神经病学   268篇
特种医学   133篇
外科学   559篇
综合类   74篇
一般理论   2篇
预防医学   326篇
眼科学   239篇
药学   286篇
中国医学   29篇
肿瘤学   247篇
  2024年   9篇
  2023年   52篇
  2022年   116篇
  2021年   207篇
  2020年   153篇
  2019年   188篇
  2018年   230篇
  2017年   153篇
  2016年   174篇
  2015年   162篇
  2014年   191篇
  2013年   258篇
  2012年   382篇
  2011年   369篇
  2010年   227篇
  2009年   181篇
  2008年   261篇
  2007年   247篇
  2006年   195篇
  2005年   134篇
  2004年   123篇
  2003年   105篇
  2002年   67篇
  2001年   17篇
  2000年   19篇
  1999年   15篇
  1998年   14篇
  1997年   9篇
  1996年   14篇
  1995年   8篇
  1994年   4篇
  1993年   4篇
  1992年   6篇
  1991年   8篇
  1990年   8篇
  1989年   8篇
  1985年   3篇
  1984年   6篇
  1983年   5篇
  1982年   6篇
  1981年   5篇
  1980年   5篇
  1979年   8篇
  1978年   6篇
  1977年   7篇
  1976年   4篇
  1975年   3篇
  1974年   6篇
  1973年   4篇
  1971年   5篇
排序方式: 共有4404条查询结果,搜索用时 46 毫秒
61.
Vitrectomy and endoresection is an alternative to enucleation for the treatment of large malignant choroidal melanoma. We report a rare case of extensive recurrence of choroidal malignant melanoma with extraocular extension 11 years after surgical endoresection without adjuvant treatment.  相似文献   
62.
63.
The stinging test is an in vivo protocol that evaluates sensitive skin using lactic acid (LA). A soothing sensation of cosmetics or ingredients can be also appreciated through a decrease in stinging score. To predict the soothing sensation of a product before in vivo testing, we developed a model based on an LA test and substance P (SP) release using a co‐culture of human keratinocytes and NGF‐differentiated PC12 cells. A bacterial fucose‐rich polysaccharide present in Fucogel® was evaluated as the soothing molecule in the in vivo stinging test and our in vitro model. Excluding toxic concentrations, the release of SP was significant from 0.2% of lactic acid for the PC12 cells and from 0.1% of lactic acid for the keratinocytes. When the pH was adjusted to approximately 7.4, LA did not provoke SP release. At these concentrations of LA, 0.1% of polysaccharide showed a significant decrease in SP release from the two cellular types and in co‐cultures without modifying the pH of the medium. In vivo, a stinging test using the polysaccharide showed a 30% decrease in prickling intensity vs the placebo in 19 women between the ages of 21 and 69. Our in vitro model is ethically interesting and is adapted for cosmetic ingredients screening because it does not use animal experimentation and limits human volunteers. Moreover, Fucogel® reduced prickling sensation as revealed by the in vivo stinging test and inhibits the neurogenic inflammation as showed by our new in vitro stinging test based on SP release.  相似文献   
64.
65.
66.
Florfenicol residues in cultured rainbow trout muscles were determined using high-performance liquid chromatography with a regulatory surveillance purpose. A total of 40 randomly selected rainbow trout fish were collected to evaluate florfenicol residue. According to the results, concentrations of the antibiotic in fish muscle were in the range of 0.4–3.6 μg g?1 (mean?=?0.8). The results show that 14 of 40 studied samples (35 %) contained florfenicol, and the concentration of florfenicol in five samples (12.5 %) was higher than maximum allowable level (1 mg kg?1). The results of this study prove the hypothesis that fish farmers use this antibiotic in large scale.  相似文献   
67.
68.
Cytokines are mediators for polarization of immune response in vaccines. Studies show that co‐immunization of DNA vaccines with granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) can increase immune responses. Here, experimental mice were immunized with HIV‐1tat/pol/gag/env DNA vaccine with GM‐CSF and boosted with recombinant vaccine. Lymphocyte proliferation with Brdu and CTL activity, IL‐4, IFN‐γ, IL‐17 cytokines, total antibody, and IgG1 and IgG2a isotypes were assessed with ELISA. Results show that GM‐CSF as adjuvant in DNA immunization significantly increased lymphocyte proliferation and IFN‐γ cytokines, but CTL response was tiny increased. Also GM‐CSF as adjuvant decreased IL‐4 cytokine vs mere vaccine group. IL‐17 in the group that immunized with mixture of DNA vaccine/GM‐CSF was significantly increased vs DNA vaccine group. Result of total antibody shows that GM‐CSF increased antibody response in which both IgG1 and IgG2a increased. Overall, results confirmed the beneficial effect of GM‐CSF as adjuvant to increase vaccine immunogenicity. The hallmark result of this study was to increase IL‐17 cytokine with DNA vaccine/GM‐CSF immunized group. This study for the first time provides the evidence of the potency of GM‐CSF in the induction of IL‐17 in response to a vaccine, which is important for control of infection such as HIV‐1.  相似文献   
69.
Effective connectivity is one of the most important considerations in brain functional mapping via EEG. It demonstrates the effects of a particular active brain region on others. In this paper, a new method is proposed which is based on dual Kalman filter. In this method, firstly by using a brain active localization method (standardized low resolution brain electromagnetic tomography) and applying it to EEG signal, active regions are extracted, and appropriate time model (multivariate autoregressive model) is fitted to extracted brain active sources for evaluating the activity and time dependence between sources. Then, dual Kalman filter is used to estimate model parameters or effective connectivity between active regions. The advantage of this method is the estimation of different brain parts activity simultaneously with the calculation of effective connectivity between active regions. By combining dual Kalman filter with brain source localization methods, in addition to the connectivity estimation between parts, source activity is updated during the time. The proposed method performance has been evaluated firstly by applying it to simulated EEG signals with interacting connectivity simulation between active parts. Noisy simulated signals with different signal to noise ratios are used for evaluating method sensitivity to noise and comparing proposed method performance with other methods. Then the method is applied to real signals and the estimation error during a sweeping window is calculated. By comparing proposed method results in different simulation (simulated and real signals), proposed method gives acceptable results with least mean square error in noisy or real conditions.  相似文献   
70.
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