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   2768篇
  免费   161篇
  国内免费   11篇
耳鼻咽喉   18篇
儿科学   63篇
妇产科学   20篇
基础医学   450篇
口腔科学   372篇
临床医学   186篇
内科学   604篇
皮肤病学   41篇
神经病学   252篇
特种医学   79篇
外科学   269篇
综合类   5篇
预防医学   151篇
眼科学   45篇
药学   211篇
中国医学   11篇
肿瘤学   163篇
  2023年   22篇
  2022年   41篇
  2021年   75篇
  2020年   46篇
  2019年   56篇
  2018年   79篇
  2017年   63篇
  2016年   76篇
  2015年   84篇
  2014年   133篇
  2013年   143篇
  2012年   228篇
  2011年   245篇
  2010年   146篇
  2009年   120篇
  2008年   222篇
  2007年   181篇
  2006年   193篇
  2005年   148篇
  2004年   154篇
  2003年   155篇
  2002年   98篇
  2001年   10篇
  2000年   13篇
  1999年   19篇
  1998年   15篇
  1997年   29篇
  1996年   20篇
  1995年   24篇
  1994年   13篇
  1993年   2篇
  1992年   8篇
  1991年   10篇
  1990年   7篇
  1989年   2篇
  1987年   6篇
  1986年   4篇
  1985年   5篇
  1984年   7篇
  1983年   4篇
  1981年   3篇
  1980年   5篇
  1979年   2篇
  1977年   2篇
  1975年   3篇
  1974年   4篇
  1971年   2篇
  1966年   2篇
  1932年   2篇
  1914年   2篇
排序方式: 共有2940条查询结果,搜索用时 31 毫秒
961.
962.
A major problem faced in sheep rearing has been the rapid acquisition of anthelminthic-resistant populations of gastrointestinal nematodes. In the search for alternatives, aqueous extract of the peel of Caryocar brasiliense was evaluated for larval development inhibition, egg-hatching inhibition, and fecal nematode egg count reduction in sheep. For in vivo analysis, the doses were calculated according to a 10% lethal dose derived from acute toxicity tests in mice, and the efficacy was evaluated for two periods following oral administration of the extract. Egg-hatching inhibition at concentrations of 15 and 7.5 mg/ml was significantly higher than observed in negative controls with distilled water. For larval development inhibition, all concentrations showed anthelminthic activity significantly higher than controls and were not significantly different from ivermectin treatment. The LC(90) of larval development inhibition was 53.19 mg/ml. In vivo analysis for first and second weeks after treatment found 32.2% and 33% anthelminthic efficacy, respectively.  相似文献   
963.
We compared 4 years of antiretroviral therapy with tenofovir/emtricitabine and either raltegravir or efavirenz from the ongoing STARTMRK study of treatment-na?ve HIV-infected patients. Through 192 weeks, raltegravir produced durable and consistent viral suppression and immune restoration compared with efavirenz irrespective of baseline demographic and prognostic factors, including in patients with high viral loads.  相似文献   
964.
965.
Thyroid pathology including thyroid nodules and diffuse thyroid diseases represents often a diagnosing challenge for clinicians. US, although highly accurate in identifying thyroid nodules and diffuse thyroid diseases, is still not sufficiently accurate to evaluate them. US-elastography has been introduced in order to further increase US accuracy in many fields and eventually for thyroid disease. The aim of the present paper it to provide an update of the literature on different available techniques and the results reported both for thyroid nodules differentiation and for diffuse thyroid disease evaluation. Advantages and limitations of elastography are also discussed.  相似文献   
966.
967.
Introduction: Parasitic diseases are a major global problem causing long-term disability and death, with severe medical and psychological consequences around the world. Despite the prevalence of parasitic disease, the treatment options for many of these illnesses are still inadequate and there is a dire need for new antiparasitic drugs. In silico screening techniques, which are powerful strategies for hit generation, are widely being applied in the design of new ligands for parasitic diseases. Areas covered: This article analyses the application of ligand- and structure-based virtual screening strategies against a variety of parasitic diseases and discusses the benefits of the integration between computational and experimental approaches toward the discovery of new antiparasitic agents. The analysis is illustrated by recent examples, with emphasis on the strategies reported within the past 2 years. Expert opinion: Virtual screening techniques are powerful tools commonly used in drug discovery against parasitic diseases, which have provided new opportunities for the identification of several novel compound classes with antiparasitic activity.  相似文献   
968.
We experimentally infected Amblyomma aureolatum ticks with the bacterium Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever (RMSF). These ticks are a vector for RMSF in Brazil. R. rickettsii was efficiently conserved by both transstadial maintenance and vertical (transovarial) transmission to 100% of the ticks through 4 laboratory generations. However, lower reproductive performance and survival of infected females was attributed to R. rickettsii infection. Therefore, because of the high susceptibility of A. aureolatum ticks to R. rickettsii infection, the deleterious effect that the bacterium causes in these ticks may contribute to the low infection rates (<1%) usually reported among field populations of A. aureolatum ticks in RMSF-endemic areas of Brazil. Because the number of infected ticks would gradually decrease after each generation, it seems unlikely that A. aureolatum ticks could sustain R. rickettsii infection over multiple successive generations solely by vertical transmission.  相似文献   
969.
A case of human intraocular dirofilariasis is reported from northern Brazil. The nematode was morphologically and phylogenetically related to Dirofilaria immitis but distinct from reference sequences, including those of D. immitis infesting dogs in the same area. A zoonotic Dirofilaria species infesting wild mammals in Brazil and its implications are discussed.  相似文献   
970.
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