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   2942篇
  免费   187篇
  国内免费   28篇
耳鼻咽喉   34篇
儿科学   59篇
妇产科学   38篇
基础医学   512篇
口腔科学   62篇
临床医学   319篇
内科学   503篇
皮肤病学   89篇
神经病学   217篇
特种医学   144篇
外科学   404篇
综合类   52篇
一般理论   1篇
预防医学   259篇
眼科学   32篇
药学   235篇
中国医学   14篇
肿瘤学   183篇
  2023年   25篇
  2022年   20篇
  2021年   58篇
  2020年   28篇
  2019年   78篇
  2018年   100篇
  2017年   68篇
  2016年   76篇
  2015年   116篇
  2014年   109篇
  2013年   132篇
  2012年   206篇
  2011年   216篇
  2010年   126篇
  2009年   107篇
  2008年   146篇
  2007年   166篇
  2006年   167篇
  2005年   135篇
  2004年   115篇
  2003年   102篇
  2002年   110篇
  2001年   44篇
  2000年   35篇
  1999年   29篇
  1998年   21篇
  1997年   21篇
  1996年   17篇
  1995年   15篇
  1994年   13篇
  1993年   13篇
  1992年   28篇
  1991年   50篇
  1990年   35篇
  1989年   38篇
  1988年   31篇
  1987年   24篇
  1986年   27篇
  1985年   45篇
  1984年   22篇
  1983年   13篇
  1979年   20篇
  1978年   14篇
  1977年   14篇
  1974年   18篇
  1973年   13篇
  1972年   18篇
  1971年   17篇
  1970年   12篇
  1967年   15篇
排序方式: 共有3157条查询结果,搜索用时 31 毫秒
91.
These guidelines, written for clinicians, contains evidence-based recommendations for the prevention of hospital acquired infections Hospital acquired infections are a major cause of mortality and morbidity and provide challenge to clinicians. Measures of infection control include identifying patients at risk of nosocomial infections, observing hand hygiene, following standard precautions to reduce transmission and strategies to reduce VAP, CR-BSI, CAUTI. Environmental factors and architectural lay out also need to be emphasized upon. Infection prevention in special subsets of patients - burns patients, include identifying sources of organism, identification of organisms, isolation if required, antibiotic prophylaxis to be used selectively, early removal of necrotic tissue, prevention of tetanus, early nutrition and surveillance. Immunodeficient and Transplant recipients are at a higher risk of opportunistic infections. The post tranplant timetable is divided into three time periods for determining risk of infections. Room ventilation, cleaning and decontamination, protective clothing with care regarding food requires special consideration. Monitoring and Surveillance are prioritized depending upon the needs. Designated infection control teams should supervise the process and help in collection and compilation of data. Antibiotic Stewardship Recommendations include constituting a team, close coordination between teams, audit, formulary restriction, de-escalation, optimizing dosing, active use of information technology among other measure. The recommendations in these guidelines are intended to support, and not replace, good clinical judgment. The recommendations are rated by a letter that indicates the strength of the recommendation and a Roman numeral that indicates the quality of evidence supporting the recommendation, so that readers can ascertain how best to apply the recommendations in their practice environments.  相似文献   
92.
93.
94.
95.
Isolators are commonly used in filling operations of pharmaceutical products. To ensure an aseptic inner environment, isolators are regularly sterilized with vaporized hydrogen peroxide. However, despite extensive purging with air, some residual H2O2 remains within the isolator atmosphere and may thus end up in the liquid pharmaceutical drug product, which subsequently may cause oxidation and impact the product’s safety and efficacy. We aimed to evaluate the extent of this phenomenon and to model it. For that purpose, we studied the diffusion of H2O2 into water contained in small recipients exposed to the atmosphere of a H2O2-sterilized small-scale test isolator. Based on the results, a mechanistic model was proposed to estimate the quantity of H2O2 in the product, taking into account the time, filling volume, H2O2 concentration, and a configuration factor. Afterward, this model was challenged by filling water at a manufacturing scale, and we observed that the diffusion model could predict the trend of increasing H2O2 concentration. However, a consistent difference in H2O2 concentration between the model and the experimental results was observed, suggesting the contribution of another parameter. Our results can be used to predict more accurately H2O2 concentration in a pharmaceutical product at the manufacturing level.  相似文献   
96.
In order to assess effect of If-channel blocker ivabradine on severity of pulmonary hypertension in chronic obstructive pulmonary disease (COPD) we studied 60 patients with III-IV stage COPD. We divided these patients into 2 groups with similar clinical characteristics and therapy. Patients of one of these groups received ivabradine (10 mg/day) for 2 weeks, patients of another served as controls. The use of ivabradine was associated with statistically significant lowering of pulmonary hypertension, heart rate, and increase of exercise tolerance without negative effects on myocardial contractility, electrophysiological parameters, or data of spirometry.  相似文献   
97.
Lasers are used for various clinical applications in dental practices, and many studies have examined the effects of lasers with different applications on enamel and dentin. The CO2 laser was introduced into the dental clinic for the removal of caries and for cavity preparation of hard tissues, in anticipation of replacing air turban and micromotor devices. The aim of this study was to examine dentin structural changes by measuring 3-dimensional diameter, depth, and volume in bovine teeth irradiated with a CO2 laser at 1, 3, or 5 W. According to our measurements, a vaporization depth of 400 μm was created by irradiation for a mere 100 ms in the case of 3 W irradiation and 500 μm in the case of 5 W irradiation. Further, at the same output power, the pulse mode transmitted energy to deeper layers of the tooth as compared with the continuous wave mode, indicating that the pulse mode has more penetrating power than the continuous wave mode. Moreover, the depth of cavity that after laser irradiated was > 500 μm at output power 5 W. Thus, irradiation at high output power and the influence of pulse mode on the pulp tissue cannot be disregarded. That is to say, it is important to consider irradiation output power, mode, direction, and distance when lasers are used for adjacent to pulp of tooth that primary incisors and deep cavities.  相似文献   
98.
Takayasu's arteritis (TA) is primary vasculitis. Cardiac involvements in TA is due to the consequences of the vascular lesions as well as the primary pathology of the heart. The disease activity of TA is known to influence the prognosis of TA. We hypothesized that the cardiovascular involvement of TA is related to the disease activity. We evaluated the cardiovascular manifestations of TA, and we assessed their relation to the disease activity of TA. Two hundred four patients were diagnosed with TA from September, 1994 to March, 2009 according to the diagnostic criteria of the 1990 American College of Rheumatology. Their clinical features and the laboratory, angiographic and echocardiographic findings were retrospectively reviewed. The group with active disease activity was defined as satisfying one of the following criteria: i) an elevated ESR or CRP level, ii) thickened arterial wall with mural enhancement on CT or MR angiography, and iii) carotidynia at the time of the initial diagnosis. One hundred thirty nine patients (69.2%) were classified as the active group. The cardiovascular signs and symptoms were not generally different between the active and inactive groups. The active TA patients had more frequent involvement of the ascending aorta and the aortic arch and its main branches than did the inactive group. The active group showed a higher incidence of significant aortic valve regurgitation and pulmonary hypertension, and a higher level of NT-proBNP. These findings suggest that disease activity plays an important role for the cardiovascular manifestations of TA. The TA patients with higher activity have more cardiovascular morbidity compared to the TA patients with low disease activity.  相似文献   
99.
100.
Mesial temporal lobe epilepsy (MTLE) is the most frequent form of focal epilepsy. At rest, there is evidence that brain abnormalities in MTLE are not limited to the epileptogenic region, but extend throughout the whole brain. It is also well established that MTLE patients suffer from episodic memory deficits. Thus, we investigated the relation between the functional connectivity seen at rest in fMRI and episodic memory impairments in MTLE. We focused on resting state BOLD activity and evaluated whether functional connectivity (FC) differences emerge from MTL seeds in left and right MTLE groups, compared with healthy controls. Results revealed significant FC reductions in both patient groups, localized in angular gyri, thalami, posterior cingulum and medial frontal cortex. We found that the FC between the left non‐pathologic MTL and the medial frontal cortex was positively correlated with the delayed recall score of a non‐verbal memory test in right MTLE patients, suggesting potential adaptive changes to preserve this memory function. In contrast, we observed a negative correlation between a verbal memory test and the FC between the left pathologic MTL and posterior cingulum in left MTLE patients, suggesting potential functional maladaptative changes in the pathologic hemisphere. Overall, the present study provides some indication that left MTLE may be more impairing than right MTLE patients to normative functional connectivity. Our data also indicates that the pattern of extra‐temporal FC may vary as a function of episodic memory material and each hemisphere's capacity for cognitive reorganization. Hum Brain Mapp 34:2202–2216, 2013. © 2012 Wiley Periodicals, Inc.  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