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   6745篇
  免费   622篇
  国内免费   16篇
耳鼻咽喉   109篇
儿科学   184篇
妇产科学   112篇
基础医学   909篇
口腔科学   217篇
临床医学   615篇
内科学   1389篇
皮肤病学   140篇
神经病学   599篇
特种医学   178篇
外国民族医学   1篇
外科学   983篇
综合类   37篇
预防医学   505篇
眼科学   142篇
药学   439篇
中国医学   28篇
肿瘤学   796篇
  2023年   28篇
  2022年   61篇
  2021年   180篇
  2020年   111篇
  2019年   220篇
  2018年   244篇
  2017年   171篇
  2016年   174篇
  2015年   214篇
  2014年   271篇
  2013年   317篇
  2012年   390篇
  2011年   421篇
  2010年   250篇
  2009年   212篇
  2008年   343篇
  2007年   337篇
  2006年   296篇
  2005年   298篇
  2004年   274篇
  2003年   246篇
  2002年   229篇
  2001年   183篇
  2000年   212篇
  1999年   165篇
  1998年   67篇
  1997年   57篇
  1996年   42篇
  1995年   48篇
  1994年   48篇
  1993年   50篇
  1992年   110篇
  1991年   118篇
  1990年   104篇
  1989年   118篇
  1988年   75篇
  1987年   82篇
  1986年   66篇
  1985年   53篇
  1984年   59篇
  1983年   29篇
  1982年   35篇
  1981年   37篇
  1980年   26篇
  1979年   46篇
  1977年   30篇
  1976年   31篇
  1974年   22篇
  1972年   21篇
  1971年   27篇
排序方式: 共有7383条查询结果,搜索用时 15 毫秒
121.
122.
123.
124.
Neural stem cells (NSCs) are regarded as a promising therapeutic approach to protecting and restoring damaged neurons in neurodegenerative diseases (NDs) such as Parkinson's disease and Alzheimer's disease (PD and AD, respectively). However, new research suggests that NSC differentiation is required to make this strategy effective. Several studies have demonstrated that melatonin increases mature neuronal markers, which reflects NSC differentiation into neurons. Nevertheless, the possible involvement of mitochondria in the effects of melatonin during NSC differentiation has not yet been fully established. We therefore tested the impact of melatonin on NSC proliferation and differentiation in an attempt to determine whether these actions depend on modulating mitochondrial activity. We measured proliferation and differentiation markers, mitochondrial structural and functional parameters as well as oxidative stress indicators and also evaluated cell transplant engraftment. This enabled us to show that melatonin (25 μM) induces NSC differentiation into oligodendrocytes and neurons. These effects depend on increased mitochondrial mass/DNA/complexes, mitochondrial respiration, and membrane potential as well as ATP synthesis in NSCs. It is also interesting to note that melatonin prevented oxidative stress caused by high levels of mitochondrial activity. Finally, we found that melatonin enriches NSC engraftment in the ND mouse model following transplantation. We concluded that a combined therapy involving transplantation of NSCs pretreated with pharmacological doses of melatonin could efficiently restore neuronal cell populations in PD and AD mouse models depending on mitochondrial activity promotion.  相似文献   
125.
IgG4-related disease is defined as a multi-organ systemic disorder with pathological findings affecting a wide range of organ systems. The condition unifies a large number of clinical diagnoses previously considered as being confined to single organ systems. At present, several issues related to its pathophysiology remained controversial, including the natural history of the disease, the pathogenic role of IgG4, and its use as a biomarker. Glucocorticoids are considered the treatment of choice for remission induction of IgG4-related disease manifestations; however, concerns regarding duration of therapy and management of refractory disease remained to be elucidated.  相似文献   
126.
Transformation is one of the mechanisms of acquisition of foreign genetic material leading to the emergence of multidrug resistant (MDR) bacteria. Recently, human serum albumin (HSA) was shown to specifically increase transformation frequency in the nosocomial pathogen Acinetobacter baumannii. To further assess the relevance of HSA as a possible modulator of A. baumannii transformation in host-pathogen interactions, in this work we examined the effect of different human fluids. We observed a significant increase in transformation frequencies in the presence of pleural fluid, whole blood cells and liquid ascites, and to a lesser extent with urine. The observed effects correlate with both HSA and bacterial content found in the assayed patient fluids. Taken together, these results are in agreement with our previous findings that highlight HSA as a possible host signal with the ability to trigger natural transformation in A. baumannii.  相似文献   
127.
128.
In 2018, the American Institute of Ultrasound in Medicine revised its obstetric Practice Parameter for the second‐trimester fetal anatomic survey. The 2018 Practice Parameter recommends incorporation of the 3‐vessel view and 3‐vessel and trachea view “if technically feasible.” Sonographers and other medical providers may require additional training and education to develop greater proficiency in obtaining and interpreting these views. This pictorial essay, including ultrasound images alongside their respective schematic diagrams, provides an up‐to‐date, practical, and clinically oriented review of the 3‐vessel view and 3‐vessel and trachea view and their most common presentations in the context of congenital heart disease.  相似文献   
129.
Conclusion: The developed software (HITCal) may be a useful tool in the analysis and measurement of the saccadic video head impulse test (vHIT) responses and with the experience obtained during its use the authors suggest that HITCal is an excellent method for enhanced exploration of vHIT outputs. Objective: To develop a (software) method to analyze and explore the vHIT responses, mainly saccades. Methods: HITCal was written using a computational development program; the function to access a vHIT file was programmed; extended head impulse exploration and measurement tools were created and an automated saccade analysis was developed using an experimental algorithm. For pre-release HITCal laboratory tests, a database of head impulse tests (HITs) was created with the data collected retrospectively in three reference centers. This HITs database was evaluated by humans and was also computed with HITCal. Results: The authors have successfully built HITCal and it has been released as open source software; the developed software was fully operative and all the proposed characteristics were incorporated in the released version. The automated saccades algorithm implemented in HITCal has good concordance with the assessment by human observers (Cohen’s kappa coefficient = 0.7).  相似文献   
130.
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