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   184103篇
  免费   1720篇
  国内免费   46篇
耳鼻咽喉   1202篇
儿科学   6753篇
妇产科学   3116篇
基础医学   17610篇
口腔科学   1883篇
临床医学   13236篇
内科学   32795篇
皮肤病学   915篇
神经病学   17332篇
特种医学   9686篇
外科学   30163篇
综合类   2365篇
一般理论   8篇
预防医学   18441篇
眼科学   2895篇
药学   9960篇
中国医学   636篇
肿瘤学   16873篇
  2023年   143篇
  2022年   272篇
  2021年   575篇
  2020年   282篇
  2019年   450篇
  2018年   22331篇
  2017年   17661篇
  2016年   19829篇
  2015年   1346篇
  2014年   1314篇
  2013年   1367篇
  2012年   7813篇
  2011年   21739篇
  2010年   19215篇
  2009年   11900篇
  2008年   19979篇
  2007年   22135篇
  2006年   932篇
  2005年   2479篇
  2004年   3665篇
  2003年   4586篇
  2002年   2662篇
  2001年   320篇
  2000年   442篇
  1999年   198篇
  1998年   245篇
  1997年   240篇
  1996年   107篇
  1995年   115篇
  1994年   115篇
  1993年   72篇
  1992年   54篇
  1991年   101篇
  1990年   136篇
  1989年   93篇
  1988年   61篇
  1987年   51篇
  1986年   37篇
  1985年   41篇
  1984年   26篇
  1983年   26篇
  1982年   34篇
  1980年   50篇
  1974年   25篇
  1939年   23篇
  1938年   63篇
  1937年   29篇
  1934年   31篇
  1932年   62篇
  1930年   58篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
981.
Not only does erectile dysfunction (ED) reflect penile vascular disorder in the majority of patients, but it also implicates their high systemic cardiovascular risk. Based on the principle of reactive hyperemia after a brief period of penile ischemia, in this study, we tested the validity of a new Penile Arterial Waveform Analyzer (PAWA) in assessing the relative increase in post-ischemic penile perfusion. Twenty young adult males (mean age 24.24 ± 2.45) without known history of cardiovascular diseases were recruited, whose anthropometric characteristics were recorded and their serum testosterone levels as well as biochemical profiles were determined. A penile cuff was applied to each subject, with cuff pressure being increased from 80 to 250 mmHg, each for 4 min, followed by reperfusion for 7 min. By dividing the area under waveform contour of hyperemic and baseline signals after Ensemble Empirical Mode Decomposition (EEMD), a Penile Perfusion Index (PPI) was calculated. Penile Brachial Index (PBI) was also obtained for comparison. The results not only showed a significant agreement between PPI and serum testosterone levels, but also a superiority of PPI to PBI in distinguishing the high- and low-risk groups for potential ED (PPI: p = 0.039 vs. PBI: p = 0.147). PPI was also demonstrated to show significant correlations with waist circumference (p < 0.001), body mass index (p = 0.005), body weight, total triglyceride, high-density lipoprotein, and systolic and diastolic pressures (all p < 0.05). In conclusion, we proposed a portable and easy-to-operate system in assessing the relative increase in penile perfusion after brief ischemia. The PPI thus obtained correlated significantly with serum testosterone levels as well as key anthropometric and serum biochemical parameters even in apparently healthy young adults, suggesting its potential as a sensitive tool in monitoring penile vascular function and risk for ED.  相似文献   
982.

Objectives  

This study aimed to compare the tolerability and efficacy of two different titrations of paroxetine (slow and standard) in a population of cancer patients with depression.  相似文献   
983.
984.

Background  

Ergosterol peroxide (EP) derived from edible mushroom has been shown to exert anti-tumor activity in several cancer cells. In the present study, anti-angiogenic activity of EP was investigated with the underlying molecular mechanisms in human multiple myeloma U266 cells.  相似文献   
985.

Background  

Curcumin (diferuloylmethane), the yellow pigment in the Asian spice turmeric, is a hydrophobic polyphenol from the rhizome of Curcuma longa. Because of its chemopreventive and chemotherapeutic potential with no discernable side effects, it has become one of the major natural agents being developed for cancer therapy. Accumulating evidence suggests that curcumin induces cell death through activation of apoptotic pathways and inhibition of cell growth and proliferation. The mitotic checkpoint, or spindle assembly checkpoint (SAC), is the major cell cycle control mechanism to delay the onset of anaphase during mitosis. One of the key regulators of the SAC is the anaphase promoting complex/cyclosome (APC/C) which ubiquitinates cyclin B and securin and targets them for proteolysis. Because APC/C not only ensures cell cycle arrest upon spindle disruption but also promotes cell death in response to prolonged mitotic arrest, it has become an attractive drug target in cancer therapy.  相似文献   
986.
Rigid cognition is frequently cited as a plausible maintenance or risk factor for depression. However, most performance-based measures of cognitive rigidity associated with depression offer poor ecological validity, produce mixed findings, and afford little in the way of therapeutic application. In order to establish a more useful and relevant performance-based measure of cognitive rigidity in depression, we developed a novel task that probes a rigidity process using stimuli highly relevant to the level of construal, the thematic content, and the rhetorical mode of depressotypic thinking. The task consists of a set of narrative vignettes that contain an expectancy-violation that is incompatible with an initially-established interpretation. As hypothesized, depressive symptoms were associated with reduced ability to update interpretations. This finding was independent of the valence of the expectancy-violation (i.e., was not merely a negativity bias), and was significant after controlling for basic set-shifting ability, intelligence measures, working memory, and other potential confounds. The novel Contingent Inference Task is a promising approach that may probe a more ecologically and etiologically relevant form of cognitive rigidity in depression than other related performance-based rigidity tasks. This rigidity process may underlie the persistence of biased beliefs in depression, and represent a new therapeutic target.  相似文献   
987.
Conventional peer review practice is compromised by a number of well-documented biases, which in turn limit standard of care analysis, which is fundamental to determination of medical malpractice. In addition to these intrinsic biases, other existing deficiencies exist in current peer review including the lack of standardization, objectivity, retrospective practice, and automation. An alternative model to address these deficiencies would be one which is completely blinded to the peer reviewer, requires independent reporting from both parties, utilizes automated data mining techniques for neutral and objective report analysis, and provides data reconciliation for resolution of finding-specific report differences. If properly implemented, this peer review model could result in creation of a standardized referenceable peer review database which could further assist in customizable education, technology refinement, and implementation of real-time context and user-specific decision support.  相似文献   
988.
Blunt abdominal trauma mostly results from motor vehicle accidents, recreational accidents, falls or assaults with commonly injured internal organs being the spleen, liver, retroperitoneum, small bowel, kidneys, bladder, colorectal, diaphragm and pancreas. Gastric rupture is quite uncommon. Isolated gastric perforations following blunt trauma to the abdomen are mostly seen in paediatric patients. It is uncommon in adult patients and even rarer is the occurrence of double gastric perforations. We report here with a case of isolated double gastric perforation in a 24-year-old male patient following vehicular accident.  相似文献   
989.
990.
Reliability of Charcot’s triad has long been questioned. Tokyo Guidelines committee published Tokyo Guidelines in 2007 and 2013. The aim of this study was to retrospectively examine the patients who had been treated with the diagnosis of acute cholangitis and evaluate 2007–2013 Tokyo criteria and Charcot’s triad. The files of the patients with acute cholangitis in a referral center were examined retrospectively. All patients were classified and evaluated according to 2007 and 2013 Tokyo criteria and Charcot’s triad; and results were compared. It was detected that 51.7 % of patients who did not meet Charcot’s triad were in definitive diagnosis group of both Tokyo criteria. Kappa value was calculated as 0.404 in the analysis of consistency between two Tokyo criteria. Two patients who had features sufficient to objectively make the diagnosis of acute cholangitis failed to meet the Tokyo criteria 2007 or 2013. Charcot’s triad is not sensitive and specific enough in the diagnosis of acute cholangitis. Revision of Tokyo 2007 criteria caused a change in the diagnostic status of 15 % of the patients. It is remarkable that kappa value can hardly be considered as a sign of moderate agreement between two Tokyo guidelines. Tokyo criteria should be supported and updated.  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