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   307528篇
  免费   9036篇
  国内免费   739篇
耳鼻咽喉   2498篇
儿科学   10815篇
妇产科学   6453篇
基础医学   35504篇
口腔科学   6149篇
临床医学   24253篇
内科学   60496篇
皮肤病学   4318篇
神经病学   29245篇
特种医学   12469篇
外国民族医学   4篇
外科学   42047篇
综合类   2868篇
一般理论   88篇
预防医学   30277篇
眼科学   4784篇
药学   18531篇
中国医学   1115篇
肿瘤学   25389篇
  2023年   1085篇
  2022年   1087篇
  2021年   4301篇
  2020年   2626篇
  2019年   3719篇
  2018年   25559篇
  2017年   20001篇
  2016年   22550篇
  2015年   4861篇
  2014年   6247篇
  2013年   7830篇
  2012年   17356篇
  2011年   31604篇
  2010年   24384篇
  2009年   16491篇
  2008年   27762篇
  2007年   30048篇
  2006年   8878篇
  2005年   9972篇
  2004年   10385篇
  2003年   10770篇
  2002年   8284篇
  2001年   1823篇
  2000年   1867篇
  1999年   1562篇
  1998年   1351篇
  1997年   1157篇
  1996年   855篇
  1995年   755篇
  1994年   688篇
  1993年   608篇
  1992年   853篇
  1991年   726篇
  1990年   803篇
  1989年   718篇
  1988年   645篇
  1987年   593篇
  1986年   552篇
  1985年   480篇
  1984年   390篇
  1983年   357篇
  1982年   310篇
  1981年   238篇
  1980年   269篇
  1979年   326篇
  1978年   231篇
  1977年   212篇
  1976年   214篇
  1975年   249篇
  1974年   285篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Journal of Medical Ultrasonics - Chronic liver disease is still a major problem because disease progression will ultimately lead to liver cirrhosis. Portal hypertension is the hallmark in advanced...  相似文献   
2.

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 We will search the following websites for ongoing or unpublished trials: http://www.controlled-trials.com/ , http://www.clinicaltrials.gov/ , www.eudraCT.com , http://centerwatch.com/ , The Cochrane Library's CENTRAL,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   
3.
4.
European Surgery - Treatment of pilonidal sinus disease (PSD) requires a tailored approach. A national guideline was published in 2014. The current status of surgical PSD therapy...  相似文献   
5.
Breast pseudoaneurysms after a core needle biopsy are a rare complication with a low incidence. However, it is important to be aware of the possibility of complications that require treatment.  相似文献   
6.
7.
8.
The regulation of food intake is a complex mechanism, and the hypothalamus is the main central structure implicated. In particular, the arcuate nucleus appears to be the most critical area in the integration of multiple peripheral signals.Among these signals, those originating from the white adipose tissue and the gastrointestinal tract are known to be involved in the regulation of food intake.The present paper focuses on adiponectin, an adipokine secreted by white adipose tissue, which is reported to have a role in the control of feeding by acting centrally. The recent observation that adiponectin is also able to influence gastric motility raises the question of whether this action represents an additional peripheral mechanism that concurs with the central effects of the hormone on food intake. This possibility, which represents an emerging aspect correlating the central and peripheral effects of adiponectin in the hunger-satiety cycle, is discussed in the present paper.  相似文献   
9.
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.  相似文献   
10.
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