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   4152篇
  免费   322篇
  国内免费   100篇
耳鼻咽喉   16篇
儿科学   16篇
妇产科学   23篇
基础医学   205篇
口腔科学   83篇
临床医学   205篇
内科学   199篇
皮肤病学   25篇
神经病学   87篇
特种医学   214篇
外科学   196篇
综合类   473篇
预防医学   437篇
眼科学   31篇
药学   1219篇
中国医学   1058篇
肿瘤学   87篇
  2024年   15篇
  2023年   50篇
  2022年   97篇
  2021年   109篇
  2020年   119篇
  2019年   84篇
  2018年   98篇
  2017年   91篇
  2016年   127篇
  2015年   103篇
  2014年   259篇
  2013年   294篇
  2012年   319篇
  2011年   381篇
  2010年   258篇
  2009年   226篇
  2008年   244篇
  2007年   232篇
  2006年   172篇
  2005年   159篇
  2004年   123篇
  2003年   111篇
  2002年   86篇
  2001年   89篇
  2000年   58篇
  1999年   55篇
  1998年   51篇
  1997年   42篇
  1996年   38篇
  1995年   42篇
  1994年   42篇
  1993年   35篇
  1992年   30篇
  1991年   27篇
  1989年   13篇
  1988年   11篇
  1987年   11篇
  1985年   21篇
  1984年   23篇
  1983年   23篇
  1982年   13篇
  1981年   16篇
  1980年   20篇
  1979年   22篇
  1978年   16篇
  1977年   18篇
  1976年   14篇
  1975年   11篇
  1974年   16篇
  1973年   15篇
排序方式: 共有4574条查询结果,搜索用时 15 毫秒
181.
182.
目的 观察脂肪乳对血液细胞分析结果的影响.方法 在体外将健康志愿者血液样本以及生理盐水与一定比例的脂肪乳混合,配制系列浓度的血液/脂肪乳混合液以及生理盐水/脂肪乳混合液,于血液细胞分析仪上进行测试,观察不同浓度脂肪乳对CBC参数、Diff分类参数的影响.结果 随着脂肪乳浓度的增高,血液/脂肪乳混合液的CBC参数测定值渐进升高,Diff分类参数中的淋巴细胞分类比例呈下降趋势而单核细胞比例逐渐增高;而生理盐水/脂肪乳混合液中白细胞、血红蛋白和PLT-O明显升高.结论 脂肪乳会对血液细胞分析仪多个参数的测定产生影响,可以通过测定结果的一些特征筛选可疑含脂肪乳标本.  相似文献   
183.
184.
The goal of public health is to promote the best possible health for the whole population. Public health issues are numerous and can be unbelievably complex in form, scope, and possible consequence. Most public health decisions involve assessing several different options, weighing the respective benefits and risks of those options, and making difficult decisions that hopefully provide the greatest benefit to the affected populations. Many risk management decisions involve a variety of societal factors which modify risk assessment choices. The purpose of this paper is to point out difficulties in making decisions that impact public health. The intent of such decisions is to improve public health, but as illustrated in the paper, there can be unintended adverse consequences. Such unplanned issues require continued attention and efforts for responsible officials in the protection of environmental public health. This article presents examples of such events, when in the past, it was necessary to assess and regulate a number of potentially hazardous chemicals commonly used as insecticides, gasoline additives, and wood preservatives.  相似文献   
185.
Photodynamic therapy (PDT) has been successfully employed in the treatment of oral cancer. Toluidine blue O (TBO) is a photosensitizer (PS) that has exhibited remarkable photocytotoxicity in a variety of tumour cells; however, its physicochemical properties, as well as the physicochemical properties of oral mucosa, prevent the drug from reaching the target site at a therapeutic concentration.The aim of this study was to evaluate the influence of Tween 80® (TW), which has shown potential as a penetration enhancer, on the mucosal retention of TBO for the PDT of oral cancer. 4% Chitosan-based mucoadhesive gels (CH gels) containing or not 5%TW were prepared (both containing 1%TBO), and their physicochemical properties (pH, rheology and mucoadhesion), TBO in vitro release profiles and TBO in vitro mucosal retention were evaluated. In vivo mucosal penetration studies of TBO followed by laser exposition were also carried out.The results showed that 4%CH gels containing 5%TW and 1%TBO have adequate mucoadhesive and rheological properties for oral mucosa use, although they present a slightly acid pH. TBO release studies showed that TW reduces TBO release, but it prolongs TBO release and increases TBO retention in the mucosa. In vivo studies showed that 4%CH gels containing 5%TW and 1%TBO cause an increase in the number of apoptotic cell, after laser exposition.In summary, 4%CH gels containing 5%TW may be a promising vehicle to optimize the penetration of TBO in oral mucosa and to improve the PDT response for the treatment of oral cancer.  相似文献   
186.
The purpose of this article is to examine the parallel in yoga, addiction, and the therapeutic process. Chemical dependency is a self-destructive process that weakens and unbalances the individual physically, emotionally, and spiritually. Yoga is a three-fold process that can rebuild these aspects of self, serving to counteract further progression of the disease. Yoga and meditation can be effective in helping the patient regain his/her vital center of energy, satisfaction and stability while making positive changes in their lives. Emphasis is placed on how the application of yoga in conjunction with treatment can accelerate the rehabilitative process.  相似文献   
187.
188.
Crude 4-methylcyclohexanemethanol (MCHM) is an industrial chemical used to wash and clean coal. On January 9th, 2014 approximately 10,000 gallons of a mixture containing crude MCHM were released into the Elk River near Charleston, West Virginia, contaminating the local water supply. Following the spill, residents reported numerous health complaints, and sought medical attention for ailments including rashes and itching. The relationship between the complaints and the spill were unknown, as such symptoms are reported frequently in the background. In this study, the primary irritation potential of crude MCHM was evaluated in 206 individuals who underwent 48?hour semi-occluded patch testing. MCHM concentrations assessed in this study were 1, 5, 15, and 100?ppm. No appreciable skin reactions were observed in individuals at any concentration. Three of the five concentrations evaluated were above the highest measured concentration of MCHM in the tap water of residents in West Virginia (3.7?ppm). The results of this study suggest that crude MCHM would not be a dermal irritant for the vast majority, if not all, potentially exposed persons at the concentrations in the water reported after the spill.  相似文献   
189.
Changes in cadmium (Cd) accumulation, distribution, and chemical form in rice seedling in the joint presence of different concentrations of sulfur (S) remain almost unknown. Therefore, the indoor experiments were performed to determine the accumulation, sub-cellular distribution and chemical forms of Cd under three S levels in rice seedling for the first time. The result showed that Cd accumulation in rice roots was more than in shoots. Sub-cellular distribution of Cd in rice roots and shoots indicated that the largest proportion of Cd accumulated in cell walls and soluble fractions. As S supply increased, the proportion of Cd in cell walls reduced, while it increased in the soluble fractions. The majority of Cd existed in inorganic form, and then gradually changed to organic forms that included pectates and proteins with increased S supply. The results showed that S supply significantly influenced Cd accumulation, distribution, and chemical forms, suggesting that S might provide the material for the synthesis of sulfhydryl protein and thereby affect Cd stress on plants. These observations provided a basic understanding of potential ecotoxicological effects of joint Cd and S exposure in the environment.  相似文献   
190.
目的应用支持向量机预测水中化学耗氧量(COD)浓度。方法基于研究地区的水质监测数据,运用支持向量机算法构建水质预测模型,并对某水厂水源水中COD月均浓度进行了预测。结果建模以后预测结果显示,训练集的均方误差MSE=0.039 4,相关系数R=0.805 4,平均相对误差MRE=4.22%;两组测试集样本的相对误差分别为8.89%和0.98%。结论该模型的预测性能良好,简便易行,可以为水质预测提供新思路。  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