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   265110篇
  免费   19502篇
  国内免费   9081篇
耳鼻咽喉   2057篇
儿科学   4457篇
妇产科学   3860篇
基础医学   30581篇
口腔科学   4000篇
临床医学   24561篇
内科学   28611篇
皮肤病学   2482篇
神经病学   23762篇
特种医学   12028篇
外国民族医学   4篇
外科学   34314篇
综合类   39246篇
现状与发展   26篇
一般理论   9篇
预防医学   18484篇
眼科学   3124篇
药学   32134篇
  93篇
中国医学   15910篇
肿瘤学   13950篇
  2024年   313篇
  2023年   3492篇
  2022年   4969篇
  2021年   10774篇
  2020年   9269篇
  2019年   8662篇
  2018年   8767篇
  2017年   9701篇
  2016年   9902篇
  2015年   9425篇
  2014年   12780篇
  2013年   17910篇
  2012年   14101篇
  2011年   16714篇
  2010年   11863篇
  2009年   11666篇
  2008年   13125篇
  2007年   13973篇
  2006年   13201篇
  2005年   11918篇
  2004年   10120篇
  2003年   9100篇
  2002年   7345篇
  2001年   6536篇
  2000年   5546篇
  1999年   4683篇
  1998年   3743篇
  1997年   3755篇
  1996年   3099篇
  1995年   2864篇
  1994年   2664篇
  1993年   2228篇
  1992年   2069篇
  1991年   1861篇
  1990年   1647篇
  1989年   1385篇
  1988年   1264篇
  1987年   1182篇
  1986年   1107篇
  1985年   1577篇
  1984年   1258篇
  1983年   955篇
  1982年   962篇
  1981年   806篇
  1980年   783篇
  1979年   558篇
  1978年   366篇
  1977年   338篇
  1976年   286篇
  1975年   212篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
《Vaccine》2022,40(16):2370-2378
Porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) are two of the most common pathogens involved in the porcine respiratory disease complex (PRDC) resulting in significant economic losses worldwide. Vaccination is the most effective approach to disease prevention. Since PRRSV and Mhp co-infections are very common, an efficient dual vaccine against these pathogens is required for the global swine industry. Compared with traditional vaccines, multi-epitope vaccines have several advantages, they are comparatively easy to produce and construct, are chemically stable, and do not have an infectious potential. In this study, to develop a safe and effective vaccine, B cell and T cell epitopes of PRRSV-GP5, PRRSV-M, Mhp-P46, and Mhp-P65 protein had been screened to construct a recombinant epitope protein rEP-PM that has good hydrophilicity, strong antigenicity, and high surface accessibility, and each epitope is independent and complete. After immunization in mice, rEP-PM could induce the production of high levels of antibodies, and it had good immunoreactivity with anti-rEP-PM, anti-PRRSV, and anti-Mhp antibodies. The anti-rEP-PM antibody specifically recognizes proteins from PRRSV and Mhp. Moreover, rEP-PM induced a Th1-dominant cellular immune response in mice. Our results showed that the rEP-PM protein could be a potential candidate for the development of a safe and effective multi-epitope peptide combined vaccine to control PRRSV and Mhp infections.  相似文献   
22.
23.

Background

Hyperglycaemia is common in patients with acute brain injury admitted to an intensive care unit (ICU). Many studies have found associations between development of hyperglycaemia and increased mortality in hospitalised patients. However, the optimal target for blood glucose control is unknown. We want to conduct a systematic review with meta-analysis and trial sequential analysis to explore the beneficial and harmful effects of restrictive versus liberal glucose control on patient outcomes in adults with severe acute brain injury.

Methods

We will systematically search medical databases including CENTRAL, Embase, MEDLINE and trial registries. We will search the following websites for ongoing or unpublished trials: http://www.controlled-trials.com/ , http://www.clinicaltrials.gov/ , www.eudraCT.com , http://centerwatch.com/ , The Cochrane Library's CENTRAL, PubMed, EMBASE, Science Citation Index Expanded and CINAHL. Two authors will independently review and select trials and extract data. We will include randomised trials comparing levels of glucose control in our analyses and observational studies will be included to address potential harms. The primary outcomes are defined as all-cause mortality, functional outcome and health-related quality of life. Secondary outcomes include serious adverse events including hypoglycaemia, length of ICU stay and duration of mechanical ventilation, and explorative outcomes including intracranial pressure and infection. Trial Sequential Analysis will be used to investigate the risk of type I error due to repetitive testing and to further explore imprecision. Quality of trials will be evaluated using the Cochrane Risk of Bias tool, and quality of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

Discussion

The results of the systematic review will be disseminated through peer-reviewed publication. With the review, we hope to inform future randomised clinical trials and improve clinical practice.  相似文献   
24.
25.
26.
27.
MicroRNAs (miRNAs) play important roles in prostate cancer development. However, it remains unclear how individual miRNAs contribute to the initiation and progression of prostate cancer. Here we show that a basal layer‐enriched miRNA is required for prostate tumorigenesis. We identify miR‐205 as the most highly expressed miRNA and enriched in the basal cells of the prostate. Although miR‐205 is not required for normal prostate development and homeostasis, genetic deletion of miR‐205 in a Pten null tumor model significantly compromises tumor progression and does not promote metastasis. In Pten null basal cells, loss of miR‐205 attenuates pAkt levels and promotes cellular senescence. Furthermore, although overexpression of miR‐205 in prostate cancer cells with luminal phenotypes inhibits cell growth in both human and mouse, miR‐205 has a minimal effect on the growth of a normal human prostate cell line. Taken together, we have provided genetic evidence for a requirement of miR‐205 in the progression of Pten null‐induced prostate cancer.  相似文献   
28.
This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.  相似文献   

29.
30.
《中国现代医生》2020,58(9):144-146+封三
目的探讨MSCT在对比剂外渗的急性腹部创伤性动脉损伤诊断中的应用价值。方法回顾性分析本院2016年1月~2018年12月收治的44例急性创伤性腹部动脉损伤患者及58例腹部非创伤性动脉病变患者影像资料,分析急性腹部创伤性和非创伤性动脉病变所致对比剂外渗的相关性。结果 44例创伤性腹部损伤患者通过MSCT及图像后处理技术共检出59支动脉损伤,其中对比剂外渗34支、非对比剂外渗共25支;58例急性腹部非创伤组共检出58支动脉病变,其中8支存在对比剂外渗。对比剂外渗征象创伤组出现率明显高于非创伤性组(χ~2=24.42,P0.05)。结论与非创伤组相比,急性腹部创伤性动脉损伤对比剂外渗征象较为常见,MSCT可以较好地显示创伤性对比剂外渗的直接及间接征象。  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