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   4211篇
  免费   319篇
  国内免费   38篇
耳鼻咽喉   42篇
儿科学   76篇
妇产科学   79篇
基础医学   587篇
口腔科学   71篇
临床医学   392篇
内科学   958篇
皮肤病学   82篇
神经病学   275篇
特种医学   143篇
外科学   574篇
综合类   76篇
一般理论   2篇
预防医学   330篇
眼科学   238篇
药学   313篇
中国医学   79篇
肿瘤学   251篇
  2024年   9篇
  2023年   55篇
  2022年   123篇
  2021年   225篇
  2020年   166篇
  2019年   200篇
  2018年   243篇
  2017年   160篇
  2016年   189篇
  2015年   171篇
  2014年   204篇
  2013年   277篇
  2012年   383篇
  2011年   373篇
  2010年   230篇
  2009年   184篇
  2008年   265篇
  2007年   251篇
  2006年   196篇
  2005年   138篇
  2004年   127篇
  2003年   108篇
  2002年   67篇
  2001年   19篇
  2000年   21篇
  1999年   15篇
  1998年   15篇
  1997年   9篇
  1996年   14篇
  1995年   8篇
  1994年   6篇
  1993年   4篇
  1992年   5篇
  1991年   7篇
  1990年   8篇
  1989年   8篇
  1987年   3篇
  1985年   3篇
  1984年   6篇
  1983年   5篇
  1982年   6篇
  1981年   6篇
  1980年   6篇
  1979年   8篇
  1978年   6篇
  1977年   7篇
  1976年   5篇
  1974年   4篇
  1973年   4篇
  1971年   4篇
排序方式: 共有4568条查询结果,搜索用时 738 毫秒
61.
β-Thalassemia major (β-TM) is an inherited disease and efforts have been made in several countries to reduce the number of affected births. In the present study, we aimed to evaluate the Iranian thalassemia prevention program, considered to be an important program in the region. The time period of the present study ranges from 2007–2009, during which new thalassemic births and the relevant causes were evaluated throughout the country. A cross-sectional analytical study was conducted at the Iranian Blood Transfusion Organization (IBTO), Tehran, Iran. A questionnaire was forwarded to all blood centers of the IBTO so as to obtain information about the new cases of thalassemia and the causes of these thalassemic births. Provincial thalassemia societies also received the questionnaires so that screening and prenatal diagnosis (PND) errors would be recorded. The results showed that 755 new thalassemia cases were born during 2007–2009 with the average fall in affected thalassemia births of 80.82%. The main cause of the new births was attributed to unregistered “timeless religious marriages” based on the conventions of the Sunni community which accounted for 43.17% of all new cases mainly having occurred in Sistan & Baluchestan Province. Not using PND was evaluated to be another main cause. Although the prevention program has led to a great reduction in thalassemic births, new measures are required, including research on how to make the program compatible with social and economic conventions and norms of Sistan & Baluchestan Province. The province of Kohgiluyeh Boyer Ahmad also needs to be revisited in terms of the program efficacy.  相似文献   
62.
63.
In this work we proposed a model for in vitro interaction of fenitrothion (FEN) with calf thymus-DNA by combination of multispectroscopic and two dimensional molecular modeling (ONIOM) methods. The circular dichroism results showed that FEN changes the conformation of B-DNA and caused some changes to C-DNA form. The FT-IR results confirmed a partial intercalation between FEN and edges of all base pairs. The competitive fluorescence, using methylene blue as fluorescence probe, in the presence of increasing amounts of FEN, revealed that FEN is able to release the non-intercalated methylene blue from the DNA. The weak chemical shift and peak broadening of 1H NMR spectrum of FEN in the presence of DNA confirmed a non-intercalation mode. The 31P NMR showed that FEN interacts more with DNA via its –NO2 moiety. The ONIOM, based on the hybridization of QM/MM (DFT, 6.31++G (d,p)/UFF) methodology, was also performed by Gaussian 2003 package. The results revealed that the interaction is base sequence dependent, and FEN interacts more with AT base sequences.  相似文献   
64.
Vitrectomy and endoresection is an alternative to enucleation for the treatment of large malignant choroidal melanoma. We report a rare case of extensive recurrence of choroidal malignant melanoma with extraocular extension 11 years after surgical endoresection without adjuvant treatment.  相似文献   
65.
66.
The stinging test is an in vivo protocol that evaluates sensitive skin using lactic acid (LA). A soothing sensation of cosmetics or ingredients can be also appreciated through a decrease in stinging score. To predict the soothing sensation of a product before in vivo testing, we developed a model based on an LA test and substance P (SP) release using a co‐culture of human keratinocytes and NGF‐differentiated PC12 cells. A bacterial fucose‐rich polysaccharide present in Fucogel® was evaluated as the soothing molecule in the in vivo stinging test and our in vitro model. Excluding toxic concentrations, the release of SP was significant from 0.2% of lactic acid for the PC12 cells and from 0.1% of lactic acid for the keratinocytes. When the pH was adjusted to approximately 7.4, LA did not provoke SP release. At these concentrations of LA, 0.1% of polysaccharide showed a significant decrease in SP release from the two cellular types and in co‐cultures without modifying the pH of the medium. In vivo, a stinging test using the polysaccharide showed a 30% decrease in prickling intensity vs the placebo in 19 women between the ages of 21 and 69. Our in vitro model is ethically interesting and is adapted for cosmetic ingredients screening because it does not use animal experimentation and limits human volunteers. Moreover, Fucogel® reduced prickling sensation as revealed by the in vivo stinging test and inhibits the neurogenic inflammation as showed by our new in vitro stinging test based on SP release.  相似文献   
67.
68.
69.
Florfenicol residues in cultured rainbow trout muscles were determined using high-performance liquid chromatography with a regulatory surveillance purpose. A total of 40 randomly selected rainbow trout fish were collected to evaluate florfenicol residue. According to the results, concentrations of the antibiotic in fish muscle were in the range of 0.4–3.6 μg g?1 (mean?=?0.8). The results show that 14 of 40 studied samples (35 %) contained florfenicol, and the concentration of florfenicol in five samples (12.5 %) was higher than maximum allowable level (1 mg kg?1). The results of this study prove the hypothesis that fish farmers use this antibiotic in large scale.  相似文献   
70.
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