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   615737篇
  免费   43500篇
  国内免费   30384篇
耳鼻咽喉   4490篇
儿科学   11945篇
妇产科学   7829篇
基础医学   65210篇
口腔科学   8989篇
临床医学   75372篇
内科学   90259篇
皮肤病学   5309篇
神经病学   38020篇
特种医学   24889篇
外国民族医学   262篇
外科学   68195篇
综合类   84328篇
现状与发展   100篇
一般理论   42篇
预防医学   49942篇
眼科学   15631篇
药学   56719篇
  615篇
中国医学   30239篇
肿瘤学   51236篇
  2025年   89篇
  2024年   5515篇
  2023年   8495篇
  2022年   17824篇
  2021年   22046篇
  2020年   17962篇
  2019年   14006篇
  2018年   35173篇
  2017年   30198篇
  2016年   31391篇
  2015年   20578篇
  2014年   25368篇
  2013年   22913篇
  2012年   39592篇
  2011年   57254篇
  2010年   42846篇
  2009年   31285篇
  2008年   43633篇
  2007年   45641篇
  2006年   24168篇
  2005年   24879篇
  2004年   18043篇
  2003年   18523篇
  2002年   14260篇
  2001年   10452篇
  2000年   10431篇
  1999年   10351篇
  1998年   6689篇
  1997年   6398篇
  1996年   4965篇
  1995年   4654篇
  1994年   3916篇
  1993年   2510篇
  1992年   2983篇
  1991年   2631篇
  1990年   2309篇
  1989年   1988篇
  1988年   1635篇
  1987年   1468篇
  1986年   1176篇
  1985年   861篇
  1984年   459篇
  1983年   336篇
  1982年   204篇
  1981年   195篇
  1980年   176篇
  1979年   179篇
  1978年   81篇
  1938年   62篇
  1932年   61篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Background: In this study, we coordinated a network meta‐analysis to establish the efficacy and safety of different agents used in the treatment of hyperphosphatemia patients with chronic kidney disease. Methods: PubMed, CNKI, and Embase were systematically searched to retrieve relevant studies. Outcomes were presented by mean differences, odds ratios, and corresponding 95% credible intervals for continuous outcomes and binary outcomes, respectively. Each therapy was ranked according to the value of surface under the cumulative ranking curve. Consistencies between direct and indirect comparisons were assessed with a node‐splitting plot. Results: In terms of efficacy end points (including levels of serum phosphate, serum calcium, serum intact parathyroid hormone, and serum calcium × phosphorus product), all 7 kinds of agents outperformed or performed at least equally to placebo, with iron‐based phosphate‐binding agents being potentially the most effective. As for safety end points (including mortality, adverse events, and all‐cause discontinuation), almost all agents were equivalent in term of mortality and all‐cause discontinuation except in the comparison between iron‐based phosphate‐binding agents and placebo. Meanwhile, iron‐based phosphate‐binding agents colestilan and nicotinic acid performed poorly compared with placebo in terms of adverse events. Furthermore, iron‐based phosphate‐binding agents were potentially the safest agents followed sequentially by calcium‐based phosphate‐binding agents and placebo. Conclusion: Iron‐based phosphate‐binding agents were the preferable agents when considering efficacy and safety simultaneously.  相似文献   
102.
103.
104.
105.
106.
107.
The purpose of this study is to develop a novel breast abnormality detection system by utilizing the potential of infrared breast thermography (IBT) in early breast abnormality detection. Since the temperature distributions are different in normal and abnormal thermograms and hot thermal patches are visible in abnormal thermograms, the abnormal thermograms possess more complex information than the normal thermograms. Here, the proposed method exploits the presence of hot thermal patches and vascular changes by using the power law transformation for pre-processing and singular value decomposition to characterize the thermal patches. The extracted singular values are found to be statistically significant (p?<?0.001) in breast abnormality detection. The discriminability of the singular values is evaluated by using seven different classifiers incorporating tenfold cross-validations, where the thermograms of the Department of Biotechnology-Tripura University-Jadavpur University (DBT-TU-JU) and Database of Mastology Research (DMR) databases are used. In DMR database, the highest classification accuracy of 98.00% with the area under the ROC curve (AUC) of 0.9862 is achieved with the support vector machine using polynomial kernel. The same for the DBT-TU-JU database is 92.50% with AUC of 0.9680 using the same classifier. The comparison of the proposed method with the other reported methods concludes that the proposed method outperforms the other existing methods as well as other traditional feature sets used in IBT based breast abnormality detection. Moreover, by using Rank1 and Rank2 singular values, a breast abnormality grading (BAG) index has also been developed for grading the thermograms based on their degree of abnormality.  相似文献   
108.
The aims of this study were to evaluate the weekly and annual cumulative radiofrequency-electromagnetic field (RF-EMF) exposure attributed to mobile phone (MP) use, and assess whether a novel app (Quanta Monitor?) could be employed in a small human sample to characterise the RF-EMF exposures associated with the use of MPs. Ten participants provided their two months’ daily objective data on their MP exposures (i.e. transmitted and received power densities) attributed to different modes of MP usage such as cellular calls, cellular data and Wi-Fi. The results demonstrated that total transmitted power density (cellular phone calls, data and Wi-Fi surfing) could be many orders of magnitude higher than that from the total received power density. Of the total transmitted power density, cellular data use contributed the largest portion. Our study showed that Quanta Monitor? could be employed in prospective assessment of exposures to MPs in epidemiological studies.  相似文献   
109.

Aim

To provide a systematic review of the existing theory, framework, systems and instruments for tracing and evaluating quality in rural health services.

Subjects and methods

We searched six electronic databases up to March 2016. Observational studies of quality assessment of rural health services using theoretical models were included. Ekman’s scale was used to evaluate the quality of the included studies.

Results

A total of 18 studies, published between 2001 and 2015, met the inclusion criteria. The corresponding authors for most of them (7, 44%) are from Chinese institutions and three (3, 17%) from Australian institutions. Five studies (28%) focused on township hospitals. Primary health care quality was reported in five studies (28%), followed by clinical service in four (22%). More than half of the studies (61%) were considered of high quality, and the remainder was of moderate quality. These studies applied 16 theoretical systems, including the model/pattern (4, 25%), method/tool (7, 44%) and framework of the theory (5, 31%). Most of the theoretical models (14, 88%) obtained positive observations. In addition, the conceptual model (6, 36%) and TOPSIS method (2, 13%) were more frequently reported.

Conclusion

Although most of the current studies were considered to have high-quality and positive results, there were limitations in the number of publications and research on theoretical systems. The lacks of unified standards and comprehensive evaluation are important issues that need to be pointed out and resolved.
  相似文献   
110.
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