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   233019篇
  免费   21977篇
  国内免费   13082篇
耳鼻咽喉   2220篇
儿科学   2526篇
妇产科学   3451篇
基础医学   29581篇
口腔科学   4573篇
临床医学   28283篇
内科学   36433篇
皮肤病学   3090篇
神经病学   13137篇
特种医学   8076篇
外国民族医学   103篇
外科学   25898篇
综合类   33452篇
现状与发展   40篇
一般理论   27篇
预防医学   15102篇
眼科学   6121篇
药学   24216篇
  195篇
中国医学   12039篇
肿瘤学   19515篇
  2024年   2397篇
  2023年   3255篇
  2022年   8116篇
  2021年   10346篇
  2020年   7873篇
  2019年   6966篇
  2018年   7665篇
  2017年   6919篇
  2016年   6534篇
  2015年   9606篇
  2014年   11748篇
  2013年   11234篇
  2012年   16236篇
  2011年   17299篇
  2010年   10987篇
  2009年   8696篇
  2008年   11739篇
  2007年   11323篇
  2006年   10819篇
  2005年   10267篇
  2004年   6951篇
  2003年   6412篇
  2002年   5481篇
  2001年   7944篇
  2000年   8047篇
  1999年   7523篇
  1998年   3542篇
  1997年   3268篇
  1996年   2367篇
  1995年   2214篇
  1994年   1943篇
  1993年   1303篇
  1992年   3118篇
  1991年   2718篇
  1990年   2346篇
  1989年   2242篇
  1988年   1972篇
  1987年   1740篇
  1986年   1453篇
  1985年   1244篇
  1984年   751篇
  1983年   603篇
  1982年   323篇
  1981年   290篇
  1980年   210篇
  1979年   387篇
  1978年   129篇
  1977年   112篇
  1974年   119篇
  1973年   124篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Two new secoiridoid glucosides, ilexpublignoside (1), pubzenoside (2), and a new lignan, ilexlignan B (3), along with seven known compounds (4–10) were isolated from the roots of Ilex pubescens for the first time. Their chemical structures were elucidated on the basis of extensive spectroscopic methods, including IR, UV, HR-ESI–MS, CD, NMR experiments, as well as comparison with the reported data.  相似文献   
42.
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   
43.
44.
45.
46.

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   
47.
Single particle inductively coupled plasma mass spectrometry (spICP-MS) was used to detect Ti-containing particles in heavily-used bathing areas of a river (Salt River) and five swimming pools. Ti-containing particle concentrations in swimming pools ranged from 2.8?×?103 to 4.4?×?103 particles/mL and were an order of magnitude lower than those detected in the Salt River. Measurements from the Salt River showed an 80% increase in Ti-containing particle concentration over baseline concentration during peak recreational activity (at 16:00 h) in the river. Cloud point extraction followed by transmission electron microscopy with energy dispersive X-ray analysis confirmed presence of aggregated TiO2 particles in river samples, showing morphological similarity to particles present in an over-the-counter sunscreen product. The maximum particle mass concentration detected in a sample from the Salt River (659 ng/L) is only slightly lower than the predicted no effect concentration for TiO2 to aquatic organisms (<?1 μg/L).  相似文献   
48.
49.
50.
Introduction: High-mobility group box 1 (HMGB1) is a ubiquitous nuclear protein that promotes inflammation when released extracellularly after cellular activation, stress, damage or death. HMGB1 operates as one of the most intriguing molecules in inflammatory disorders via recently elucidated signal and molecular transport mechanisms. Treatments based on antagonists specifically targeting extracellular HMGB1 have generated encouraging results in a wide number of experimental models of infectious and sterile inflammation. Clinical studies are still to come.

Areas covered: We here summarize recent advances regarding pathways for extracellular HMGB1 release, receptor usage, and functional consequences of post-translational modifications. The review also addresses results of preclinical HMGB1-targeted therapy studies in multiple inflammatory conditions and outlines the current status of emerging clinical HMGB1-specific antagonists.

Expert opinion: Blocking excessive amounts of extracellular HMGB1, particularly the disulfide isoform, offers an attractive clinical opportunity to ameliorate systemic inflammatory diseases. Therapeutic interventions to regulate intracellular HMGB1 biology must still await a deeper understanding of intracellular HMGB1 functions. Future work is needed to create more robust assays to evaluate functional bioactivity of HMGB1 antagonists. Forthcoming clinical studies would also greatly benefit from a development of antibody-based assays to quantify HMGB1 redox isoforms, presently assessed by mass spectrometry methods.  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