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   5137篇
  免费   246篇
  国内免费   6篇
耳鼻咽喉   57篇
儿科学   522篇
妇产科学   106篇
基础医学   630篇
口腔科学   89篇
临床医学   307篇
内科学   1024篇
皮肤病学   123篇
神经病学   220篇
特种医学   84篇
外科学   620篇
综合类   105篇
预防医学   333篇
眼科学   229篇
药学   643篇
中国医学   34篇
肿瘤学   263篇
  2022年   62篇
  2021年   101篇
  2020年   64篇
  2019年   77篇
  2018年   121篇
  2017年   79篇
  2016年   101篇
  2015年   125篇
  2014年   166篇
  2013年   217篇
  2012年   285篇
  2011年   301篇
  2010年   202篇
  2009年   152篇
  2008年   279篇
  2007年   271篇
  2006年   287篇
  2005年   247篇
  2004年   253篇
  2003年   227篇
  2002年   169篇
  2001年   117篇
  2000年   141篇
  1999年   111篇
  1998年   36篇
  1997年   26篇
  1996年   21篇
  1994年   20篇
  1993年   32篇
  1992年   73篇
  1991年   67篇
  1990年   71篇
  1989年   65篇
  1988年   70篇
  1987年   59篇
  1986年   59篇
  1985年   64篇
  1984年   51篇
  1983年   41篇
  1980年   37篇
  1979年   38篇
  1978年   31篇
  1977年   30篇
  1975年   37篇
  1974年   38篇
  1973年   23篇
  1972年   25篇
  1971年   26篇
  1970年   31篇
  1969年   19篇
排序方式: 共有5389条查询结果,搜索用时 0 毫秒
91.
The use of drug powders containing micronized drug particles has been increasing in several pharmaceutical dosage forms to overcome the dissolution and bioavailability problems. Most of the newly developed drugs are poorly water soluble which limits dissolution rate and bioavailability. The dissolution rate can be enhanced by micronization of the drug particles. The properties of the micronized drug substance such as particle size, size distribution, shape, surface properties, and agglomeration behaviour and powder flow are affected by the type of micronization technique used. Mechanical communition, spray drying and supercritical fluid (SCF) technology are the most commonly employed techniques for production of micronized drug particles but the characteristics of the resulting drug product cannot be controlled using these techniques. Hence, a newer technique called in situ micronization is developed in order to overcome the limitations associated with the other techniques. This review summarizes the existing knowledge on in situ micronization techniques. The properties of the resulting drug substance obtained by in situ micronization were also compared.  相似文献   
92.
Anita Saxena 《Global Heart》2013,8(3):203-212
Rheumatic heart disease continues to be a significant public health problem in many developing countries and in some of the aboriginal populations in developed countries. Echocardiography has become indispensable in the assessment of valve lesions secondary to rheumatic heart disease. It confirms the rheumatic etiology of valvular abnormality as the features are quite typical in most cases. It also helps to exclude nonrheumatic causes of valve lesions. M-mode and cross-sectional echo helps to assess the severity of valve abnormality and its hemodynamic effects on the heart. Further, color flow imaging evaluates the flow across a valve, both qualitatively and quantitatively. Serial echocardiography plays a crucial role in the follow-up of patients with rheumatic heart disease and is very helpful for determining the timing of intervention. Recently, addition of real-time 3-dimensional echocardiography has further improved imaging of cardiac valves, especially the mitral valve.  相似文献   
93.
94.
95.
In view of the drug resistance with most of the currently used anticancer drugs, molecular hybrids of pyrazolyl chalcones and p-nitro benzyl functionalities tethered by triazole ring have been synthesised and evaluated for cytotoxic studies against three human cancer cell lines (THP, COLO-205, A-549). The results of the preliminary investigation exhibited marked dependence of the cytotoxic activity on the electronic factors. Placement of naphthyl (JGPT-11) and trimethoxy phenyl ring (JGPT-6) as ring A proved to be extremely beneficial in enhancing the cytotoxic potential. Thus we herein report the synthesis and cytotoxic studies of a new class of molecular hybrids. Detailed investigation on the biological mechanistic insights of JGPT-11 and 6 is under progress.  相似文献   
96.
Pseudolipoma of inferior vena cava refers to a normal variant of adipose collection that is seen in typical pericaval or juxtacaval location; however, it mimics an intracaval mass lesion, especially fat-containing lesions such as lipoma. Awareness of this entity is very important to avoid misdiagnosis and unnecessary diagnostic procedures.  相似文献   
97.
98.
Melatonin and serotonin are important signaling and stress mitigating molecules that play important roles across growth and development in plants. Despite many well‐documented responses, a systematic investigation of the entire metabolic pathway (tryptophan, tryptamine, and N‐acetylserotonin) does not exist, leaving many open questions. The objective of this study was to determine the responses of Hypericum perforatum (L.) to melatonin, serotonin, and their metabolic precursors. Two well‐characterized germplasm lines (#4 and 112) created by mutation and a haploid breeding program were compared to wild type to identify specific responses. Germplasm line 4 has lower regenerative and photosynthetic capacity than either wild type or line 112, and there are documented significant differences in the chemistry and physiology of lines 4 and 112. Supplementation of the culture media with tryptophan, tryptamine, N‐acetylserotonin, serotonin, or melatonin partially reversed the regenerative recalcitrance and growth impairment of the germplasm lines. Quantification of phytohormones revealed crosstalk between the indoleamines and related phytohormones including cytokinin, salicylic acid, and abscisic acid. We hypothesize that melatonin and serotonin function in coordination with their metabolites in a cascade of phytochemical responses including multiple pathways and phytohormone networks to direct morphogenesis and protect photosynthesis in H. perforatum.  相似文献   
99.
100.
The complexity and increasing burden of zoonotic diseases create challenges for the health systems of developing nations. Public health systems must therefore be prepared to face existing and future disease threats at the human–animal interface. The key for this is coordinated action between the human and the animal health systems. Although some studies deal with the question of how these two systems interact during unforeseen circumstances such as outbreaks, a dearth of literature exists on how these systems interact on early detection, prevention and control of zoonotic diseases; assessing this problem from the health system perspective in a developing nation adds further complexity. Systems thinking is one of the promising approaches in understanding the factors that influence the system’s complexity and dynamics of health maintenance. Therefore, this study aims to understand the generic structure and complexity of interaction between these actors within the domain of One Health for the effectual prevention and control of zoonotic diseases in India.The present study will be executed in Ahmedabad, located on the Western part of India, in Gujarat state, using a mixed methods approach. For the first step, zoonotic diseases will be prioritised for the local context through semi-quantitative tools. Secondly, utilising semi-structured interviews, stakeholders from the human and animal health systems will be identified and ranked. Thirdly, the identified stakeholders will be questioned regarding the current strength of interactions at various levels of the health system (i.e. managerial, provider and community level) through a quantitative network survey. Fourthly, utilising a vignette method, the ideal convergence strategies will be documented and validated through policy Delphi techniques. Finally, through a participatory workshop, the factors that influence convergence for the control and prevention of zoonotic diseases will be captured.This study will provide a comprehensive picture of the current strength of collaboration and network depth at various levels of the health system. Further, it will assist different actors in identifying the relevance of possible One Health entry points for participation, i.e. it will not only contribute but will also develop a system convergence model for the effectual prevention and control of zoonotic diseases.  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