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   2941篇
  免费   284篇
  国内免费   8篇
耳鼻咽喉   6篇
儿科学   117篇
妇产科学   106篇
基础医学   520篇
口腔科学   62篇
临床医学   242篇
内科学   553篇
皮肤病学   83篇
神经病学   190篇
特种医学   240篇
外科学   390篇
综合类   88篇
一般理论   6篇
预防医学   307篇
眼科学   66篇
药学   157篇
中国医学   1篇
肿瘤学   99篇
  2022年   24篇
  2020年   25篇
  2019年   29篇
  2018年   32篇
  2017年   37篇
  2016年   24篇
  2015年   49篇
  2014年   44篇
  2013年   83篇
  2012年   109篇
  2011年   97篇
  2010年   72篇
  2009年   75篇
  2008年   104篇
  2007年   112篇
  2006年   88篇
  2005年   97篇
  2004年   96篇
  2003年   98篇
  2002年   91篇
  2001年   100篇
  2000年   108篇
  1999年   88篇
  1998年   53篇
  1997年   75篇
  1996年   66篇
  1995年   57篇
  1994年   43篇
  1993年   25篇
  1992年   66篇
  1991年   64篇
  1990年   90篇
  1989年   68篇
  1988年   63篇
  1987年   71篇
  1986年   90篇
  1985年   63篇
  1984年   48篇
  1983年   48篇
  1982年   35篇
  1981年   32篇
  1980年   38篇
  1979年   65篇
  1978年   48篇
  1977年   45篇
  1976年   27篇
  1975年   27篇
  1974年   30篇
  1972年   24篇
  1969年   26篇
排序方式: 共有3233条查询结果,搜索用时 10 毫秒
91.
92.
There is limited information about anxiety disorders occurring in the context of the challenging condition of hydrocephalus. This paper describes the treatment, via trauma-focused cognitive behaviour therapy (TFCBT), of post-traumatic stress symptoms arising on account of hydrocephalus in a 23-year-old man. Specific components of the intervention included exposure, cognitive disputation, and relaxation training. The 20-session intervention appeared effective with decreases in anxiety (on the Hospital Anxiety and Depression Scale) and event impact (on the Impact of Events Scale) from clinical to sub-clinical levels. The main contributor to change appeared to be the exposure element of the treatment. The benefits of the intervention were maintained at one-, three-, and six-month follow-up.  相似文献   
93.
Background Beliefs about the controllability of behaviour have been consistently shown to be important in understanding the responses of carers to the challenging behaviour of people with intellectual disabilities (IDs). This paper reports the reliability and validity of the Controllability Beliefs Scale (CBS), a 15‐item measure of beliefs regarding the controllability of challenging behaviour when used with carers of people with IDs. Methods Two hundred and sixty‐four carers of people with IDs completed the CBS, 74 people also completed the Modified Attributional Style Questionnaire and the Self‐Injury Behavioural Understanding Questionnaire scale to determine concurrent and convergent validity and 34 people completed the scale twice within a 2‐ to 4‐week period to determine test–retest reliability. Results The scale has a two‐factor structure and has adequate internal reliable. The scale is significantly correlated with the controllability, internality and stability items from the Modified Attributional Style Questionnaire, showed expected associations with behavioural and internal emotional understanding items from the Self‐Injury Behavioural Understanding Questionnaire. The scale has good test–retest reliability. Conclusions The data support use of the CBS in clinical practice and research to assess carers' beliefs regarding challenging behaviour of people with IDs.  相似文献   
94.
CO2 utilization in upsteam oil and gas applications requires CO2-soluble additives such as polymers, surfactants, and other components. Here we report the facile synthesis of CO2-soluble oxidizers composed of judiciously selected organic cations paired with oxidizing anions. [Bu4N]BrO3 and [Bu4N]ClO3 are prepared using a double displacement synthetic strategy, whereby the crystalline product is readily obtained in high yield and structurally characterized using single-crystal X-ray diffraction. The facility of the approach is demonstrated through the preparation of several additional alkylammonium bromate compounds. Static solubility studies using a high-pressure cell with viewing windows showed that tetrabutylammonium compounds could be solubilized using cosolvent-modified CO2. Using 4 mol% ethanol as cosolvent, >3 mM [Bu4N]BrO3 could be dissolved in CO2, while ∼0.75 mM [Bu4N]ClO3 could be dissolved in the same solvent system. The solubility properties of [Bu4N]BrO3 along with its thermal stability up to ∼200 °C suggest that it is a promising oilfield oxidizer that can be utilized in subterranean CO2 applications.

Bromate and chlorate salts were hydrophobically modified with tetrabutylammonium to yield oxidizers that are soluble in CO2-cosolvent mixtures.  相似文献   
95.
96.
Journal of Autism and Developmental Disorders - Camouflaging refers to strategies used by autistic people to mask or hide social difficulties. The current study draws on Social Identity Theory to...  相似文献   
97.
Tumor necrosis factor-alpha (TNF-alpha) decreased the expression of pulmonary surfactant proteins SP-A and SP-B in human pulmonary adenocarcinoma cell lines. The effect of TNF alpha on SP-A content and mRNA in the pulmonary adenocarcinoma cell line, H441-4, was concentration and time dependent. TNF alpha decreased the cellular content of SP-A to less than 10% of control 48 h after addition. TNF alpha decreased de novo synthesis of SP-A and decreased the accumulation of SP-A in media. SP-A mRNA was decreased within 12 h of addition of TNF alpha, with nearly complete loss of SP-A mRNA observed after 24 h. Inhibitory effects of TNF alpha on SP-A mRNA were dose-related with nearly complete inhibition of SP-A mRNA caused by 25 ng/ml TNF alpha. The effects of TNF alpha on SP-A were distinct from the effects of interferon gamma which increased SP-A content approximately twofold in H441-4 cells. TNF alpha also decreased the content of SP-B mRNA. In contrast to the inhibitory effect of TNF alpha on SP-A and SP-B mRNA, TNF alpha increased mRNA encoding human manganese superoxide dismutase (Mn-SOD). TNF alpha did not inhibit growth, alter cell viability or beta-actin mRNA in either cell line. These in vitro studies demonstrate the marked pretranslational inhibitory effects of the cytokine, TNF alpha, on the expression of pulmonary surfactant proteins, SP-A and SP-B. The results support the concept that macrophage-derived cytokines may control surfactant protein expression.  相似文献   
98.

Background

The nontechnical and team skills of surgical teams are critical for safety and efficiency in the operating room. Assessment of nontechnical and team skills can facilitate improvement by encouraging both self-reflection and team reflection, identifying training needs, and informing operating room (OR) team training approaches. The observational teamwork assessment for surgery (OTAS) tool is a well-validated and robust tool for capturing teamwork in the operating room. The aims of the present study were to systematically adapt and refine the OTAS for German-speaking OR staff and to test the adapted assessment tool (OTAS-D) for psychometric properties and metric equivalence.

Methods

The study was carried out in three stages: at stage 1, OTAS was translated into German. At stage 2, experienced German OR experts (surgeons, OR nurses, anesthetists) were interviewed. At stage 3, two blinded assessors observed 11 general surgical operations (general surgical and vascular procedures) and interrater reliability was tested for refined OTAS-D behavioral exemplars and scorings.

Results

The German OR experts confirmed the applicability and content validity of the vast majority of translated behavioral exemplars. After their evaluation, 32 items were changed slightly, six were changed substantially, and one item was added. During observations, perfect and substantial interobserver agreement was found for 77 behavioral exemplars (67.1 % of the items, kappa coefficient >0.60). Rating at all OTAS behaviors showed acceptable levels of reliability (intraclass correlation coefficients >0.72).

Conclusions

The OTAS-D is a tool for valid and reliable assessment of nontechnical skills that contribute to safe and effective surgical performance in ORs staffed by German-speaking professionals. Furthermore, our study serves as an example for systematically adapting and customizing well-established observational tools across different healthcare environments.  相似文献   
99.
100.
Summary There is now ample evidence to indicate that certain low-molecular-weight heparins given subcutaneously can replace continuous intravenous unfractionated heparin for the initial treatment of venous thromboembolism. The low-molecular-weight heparins have a predictably high absorption rate when given subcutaneously and a prolonged duration of action, permitting them to be given by a once or twice daily injection for the prevention or treatment of venous thrombosis. Furthermore, treatment does not require laboratory monitoring, thus eliminating the need for continuous IV infusion and permitting the early discharge of patients with venous thromboembolism. This should eventually lead to the outpatient treatment of venous thromboembolism. Studies to date indicate that low-molecular-weight heparin is more cost-effective than unfractionated heparin in the treatment of venous thromboembolism and the cost effectiveness will be increased by out-of-hospital treatment. At the present time, the findings associated with any individual lowmolecular-weight heparin preparation cannot be extrapolated to different low-molecular-weight heparins, and therefore each must be evaluated in separate clinical trials. The information to date is that low-molecular-weight heparin is safer and more effective than continuous intravenous unfractionated heparin in the treatment of proximal venous thrombosis. The decreased mortality rate seen in two clinical trials, particularly in patients with metastatic cancer, was quite unexpected. This requires further confirmation in larger prospective randomized trials.  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