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   411766篇
  免费   33556篇
  国内免费   11338篇
耳鼻咽喉   4448篇
儿科学   8504篇
妇产科学   6128篇
基础医学   53728篇
口腔科学   10894篇
临床医学   31974篇
内科学   52725篇
皮肤病学   5556篇
神经病学   26045篇
特种医学   9232篇
外国民族医学   65篇
外科学   34351篇
综合类   59102篇
现状与发展   39篇
一般理论   24篇
预防医学   37451篇
眼科学   4307篇
药学   45520篇
  413篇
中国医学   35220篇
肿瘤学   30934篇
  2024年   5701篇
  2023年   8811篇
  2022年   14782篇
  2021年   18768篇
  2020年   17744篇
  2019年   19499篇
  2018年   17253篇
  2017年   16100篇
  2016年   14772篇
  2015年   15592篇
  2014年   25539篇
  2013年   27193篇
  2012年   24469篇
  2011年   27392篇
  2010年   22786篇
  2009年   20692篇
  2008年   19438篇
  2007年   18338篇
  2006年   16069篇
  2005年   13654篇
  2004年   11694篇
  2003年   10110篇
  2002年   7838篇
  2001年   6613篇
  2000年   5654篇
  1999年   4871篇
  1998年   4054篇
  1997年   3663篇
  1996年   3093篇
  1995年   2737篇
  1994年   2423篇
  1993年   2081篇
  1992年   1811篇
  1991年   1636篇
  1990年   1384篇
  1989年   1250篇
  1988年   1120篇
  1987年   953篇
  1986年   927篇
  1985年   2477篇
  1984年   2762篇
  1983年   1794篇
  1982年   2248篇
  1981年   1625篇
  1980年   1389篇
  1979年   1238篇
  1978年   990篇
  1977年   761篇
  1976年   878篇
  1975年   599篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
目的 总结貌似多发性硬化的皮层下梗死和白质脑病的常染色体显性遗传性脑动脉病(CADASIL)的临床特点.方法 报告1例经基因检查和周围神经活检确诊为CADASIL的临床资料.结果 患者腓肠神经活检可见有髓神经纤维密度轻度减少,电镜下可见神经束膜小动脉中层平滑肌细胞外大量颗粒性电子致密嗜锇颗粒物质(GOM)沉积.基因检测显示Notch3基因4号外显子Cys117Arg突变.结论 为避免CADASIL的漏诊及误诊,凡遇青年反复脑卒中发作,又无高血压、糖尿病等常见的血管病危险因素,虽无偏头痛病史,亦应注意追问家族史并做基因检测和周围神经活检.  相似文献   
72.
73.

Objective

Physicians often need uptodate, reliable and with easy access information for clinical decisions evidence based medicine (EBM) databases can be a suitable approach to meet this need. The aim of this study was to assess the knowledge, use and factors affecting the acceptance of EBM and its databases by Iranian medical residents using UTAUT model.

Method

The present research is an applied survey, the population of which consisted of 192 medical residents of Shahid Beheshti University of Medical Sciences (SBUMS) in Iran. A questionnaire was used for collecting data and SPSS software was used for data analysis.

Results

The results show that the total average score of assistants (range?=?1–5), 2.99 and 2.73 scores were respectively obtained for the awareness and use of EBM databases. The study of factors affecting the acceptance using UTAUT showed that item "performance expectancy" with an average of 3.02 is the most important factor in the acceptance of EBM databases by medical residents and items "effort expectancy", "facilitating conditions" and "social influence" are in their next ranks with an average score of 2.54, 2.45 and 2.14, respectively.

Conclusion

The findings of this study showed that the majority of medical residents do not have sufficient awareness and knowledge about concepts of EBM and still not comprehend the necessity of using EBM databases. Therefore, planning for accepting and teaching Evidence based medicine and databases is essential.  相似文献   
74.

Objective

The objective of this review is to identify enabling and inhibiting factors for mHealth adoption in low resource settings, by giving emphasis on the stakeholders representing the caregiving side. Another objective of this study is to support implementation agencies (governmental and non-governmental) in designing scalable mHealth interventions.

Methods

A PEO (Population, Exposure, Outcome) approach was used to formulate the review question. A pre-defined search strategy was implemented; Google Scholar, PubMed and gray literature were searched using alternate terms for “mHealth”, “adoption” and “developing countries”. CASP [7] tools were used to assess the quality of selected evidence. After applying inclusion and exclusion criteria on search results and critical appraisal of the selected evidence, twelve studies were selected for the review.

Results

Adoption factors operated at the levels of organization, facility-based service provider and frontline health worker. Engagement of end users during design phase, informed clinical decision making, utilization of mHealth evidence, employers’ tolerance of some personal use of devices, automation of tasks and user-friendliness of application are key enabling factors for mHealth adoption in developing countries. On the contrary, absence of national policy on mHealth, poor knowledge base on mHealth, using two systems in parallel, duplication of efforts, poor Internet connectivity and shortage of electricity are important inhibiting factors for mHealth adoption.

Conclusions

The review provides an insight about the challenges and opportunities related to mHealth adoption in developing countries. Implementation agencies should give careful consideration to these factors before designing and deploying any mHealth-enabled intervention. It is also important to understand the concept of incremental innovation so that resources spent on pilot interventions are optimized and full potential is achieved.  相似文献   
75.

Objectives

This study proposes a research model that combines information system (IS) continuance theory with the DeLone and McLean IS success model to more clearly comprehend the influences of system characteristics on electronic health record system (EMRS) adoption. As Information security management (ISM) awareness enables health workers to be better able to prevent security violations, this study further explores the effects of perceived service quality on the relationship between ISM awareness and system characteristics of EMRS.

Methods

Data were gathered from a questionnaire survey of 200 health professionals in Taiwan, and the structural equation modelling technique was utilized to test the research model.

Results

The findings of this study enrich our understanding of the effect of ISM awareness and perceived service quality on the improvement of EMRS quality in the post-adoption stage. Specifically, the results indicate that with sufficient technical support and high ISM awareness, it can facilitate to enhance the quality of system characteristics of EMRS, which in turn favourably increases users’ willing to continue using the system to advance their healthcare practices, resulting in successful adoption of EMRS.

Conclusions

This study suggests that practitioners who want to successfully implement an EMRS should not merely pay attention to the issue of system design, but also be concerned with and knowledgeable about the formulation of ISM policy and its effective implementation. A successful EMRS adoption therefore should interact well with the ISM policy and sufficient technical support, and both of technical and managerial aspects are necessary fully considered and effectively integrated for the best outcome.  相似文献   
76.
77.

Background

Dietary supplement (DS) use is prevalent among the US Armed Forces personnel, but representative cross-service comparisons and characteristics of personnel using DSs are limited.

Objective

Examine DS use and characteristics associated with use in a representative sample of US Armed Forces personnel (Army, Navy, Air Force, Marine Corps, and Coast Guard) using data from the 2011 Department of Defense Survey of Health-Related Behaviors.

Design and participants

A stratified random sample of service members (SMs) was contacted and asked to complete a questionnaire assessing personal characteristics and DS use.

Results

Overall, 69% of the 39,877 SMs reported using DSs ≥1 time per week. The most commonly used DSs were multivitamin or multiminerals (50%), antioxidants (34%), individual vitamins or minerals (33%), bodybuilding supplements (27%), fish oils (26%), herbals (16%), and weight-loss supplements (16%). Multiple logistic regression indicated overall DS use was higher among women, those with higher educational levels, Marine Corps SMs, officers, those with higher body mass index, those engaged in greater physical activity and weight training, and people in weight control programs. DS use was lower when peer groups or leadership discouraged substance abuse.

Conclusions

DS use was considerably higher in the US Armed Forces compared with civilian populations, although many demographic and lifestyle factors associated with use were similar. Some categories of DSs extensively used by SMs such as bodybuilding supplements have been associated with adverse events. Discouraging substance abuse through peer groups and leadership actions may reduce use of unnecessary or dangerous DSs.  相似文献   
78.
A roadmap for the selection of a pharmaceutical salt form for a development candidate is presented. The free base of the candidate did not have sufficient chemical stability for development. The initially selected salt form turned out to be undevelopable because it was unstable during scale-up synthesis and storage. The rationale for the new solid form screening and the criteria for selection are discussed. Before the final selection, the pH solubility profiles of the 2 new salts, a benzoate and a besylate, were compared. Atypical solubility behavior was observed for the benzoate salt in hydrochloric acid with and without normal saline. A scheme is proposed illustrating how the pKas of the counterion and active pharmaceutical ingredient, the medium composition, and final pH affect the solubility and solution equilibria of the 2 selected salt forms. This scheme also includes the equilibria between solution and solid phases in different pH ranges. The pharmaceutical importance of this research is that it sheds light on how the acidity of the counterion can affect the solubility of the selected salt form in the gastric environment. With a well-designed formulation strategy, this property potentially can be translated to optimal biopharmaceutical performance of the drug product.  相似文献   
79.
An accurate dosage determination is required in neonates when antibiotics are used. The adult data cannot be simply extrapolated to the pediatric population due to significant individual differences. We aimed to identify factors impacting ceftazidime exposure in neonates and to provide drug dosing guidance to clinicians. Forty-three neonates aged less than 60 days with proven or suspected infections were enrolled in this study. After intravenous administration, blood samples were collected, and plasma ceftazidime concentration was determined using a HPLC method. Pharmacokinetic data were fitted using a nonlinear mixed-effects model approach. One-compartmental model could nicely characterize the ceftazidime in vivo behavior. The covariate test found that the postmenstrual age (day) was strongly associated with systemic drug clearance (L/h), and the effect of body weight (kg) was identified as the covariate on distribution volume (L). Compared with the base model, the addition of covariates improved the goodness-of-fit of the final model. Model validation (bootstrap, visual predictive check, and prediction-corrected visual predictive check) suggested a robust and reliable pharmacokinetic model was developed. Personalized dosage regimens were provided based on model simulations. The intravenous dose should be adjusted according to postmenstrual age, body weight, and minimum inhibitory concentration.  相似文献   
80.
Four P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrates with human cerebrospinal fluid (CSF) concentrations and preclinical neuropharmacokinetics were used to assess in vitroin vivo extrapolation of brain penetration in preclinical species and the ability to predict human brain penetration. Unbound brain (Cb,u), unbound plasma (Cp,u), and CSF compound concentrations (CCSF) were measured in rats and nonhuman primates (NHPs), and the unbound partition coefficients (Cb,u/Cp,u and CCSF/Cp,u) were used to assess brain penetration. The results indicated that for P-gp and BCRP dual substrates, brain penetration was severally impaired in all species. In comparison, for P-gp substrates that are weak or non-BCRP substrates, improved brain penetration was observed in NHPs and humans than in rats. Overall, NHP appears to be more predictive of human brain penetration for P-gp substrates with weak or no interaction with BCRP than rat. Although CCSF does not quantitatively correspond to Cb,u for efflux transporter substrates, it is mostly within 3-fold higher of Cb,u in rat and NHP, suggesting that CCSF can be used as a surrogate for Cb,u. Taken together, a holistic approach including both in vitro transporter and in vivo neuropharmacokinetics data enables a better estimation of human brain penetration of P-gp/BCRP substrates.  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