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   795篇
  免费   52篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   12篇
妇产科学   62篇
基础医学   104篇
口腔科学   11篇
临床医学   119篇
内科学   151篇
皮肤病学   12篇
神经病学   76篇
特种医学   27篇
外科学   62篇
综合类   8篇
预防医学   86篇
眼科学   2篇
药学   51篇
中国医学   2篇
肿瘤学   56篇
  2022年   6篇
  2021年   18篇
  2020年   12篇
  2019年   11篇
  2018年   16篇
  2017年   8篇
  2015年   9篇
  2014年   13篇
  2013年   23篇
  2012年   38篇
  2011年   33篇
  2010年   24篇
  2009年   14篇
  2008年   45篇
  2007年   37篇
  2006年   30篇
  2005年   41篇
  2004年   35篇
  2003年   31篇
  2002年   32篇
  2001年   24篇
  2000年   25篇
  1999年   24篇
  1998年   12篇
  1997年   8篇
  1996年   12篇
  1995年   6篇
  1994年   6篇
  1992年   13篇
  1991年   14篇
  1990年   15篇
  1989年   8篇
  1988年   15篇
  1987年   6篇
  1986年   11篇
  1985年   14篇
  1984年   6篇
  1983年   7篇
  1981年   5篇
  1979年   6篇
  1978年   5篇
  1976年   5篇
  1975年   6篇
  1971年   4篇
  1970年   9篇
  1968年   4篇
  1967年   6篇
  1942年   13篇
  1941年   20篇
  1940年   6篇
排序方式: 共有848条查询结果,搜索用时 78 毫秒
81.
82.
83.
Recent research has suggested that variables related to specific mand topographies targeted during functional communication training (FCT) can affect treatment outcomes. These include effort, novelty of mands, previous relationships with problem behavior, and preference. However, there is little extant research on procedures for identifying which mand topographies to incorporate into FCT. In the current study, a mand topography assessment was conducted following functional analyses to identify the proficiency with which individuals used several different mand topographies. Two mand topographies (high and low proficiency) were then compared during FCT-based treatments. FCT was more effective when the mand topography identified as high proficiency was incorporated into FCT as compared to FCT that included the lower proficiency response. The results are discussed in terms of the need for individualized assessment procedures for selecting mand topographies that are targeted during FCT.  相似文献   
84.
85.
We assessed the status of point mutations associated with chloroquine resistance in pfcrt codon 76 and in pfmdr1 codon 86 among Plasmodium falciparum isolates from symptomatic patients in 3 sites in Madagascar. The in vitro susceptibility of P. falciparum isolates to quinoline-containing drugs was also determined. All isolates (N = 117) successfully typed were pfcrt wild-type, except one from Tsiroanomandidy (1 of 27). However, 67.5% (95% CI: 58.2-75.9%) of these isolates contained mutant pfmdr1 86Y. The pfmdr1 N86Y mutation is associated with higher mefloquine susceptibility, but it did not affect the sensitivity of parasites to chloroquine or quinine. Our findings demonstrate that pfmdr1 mutant P. falciparum are prevalent in Madagascar and confirm the low prevalence of pfcrt mutant P. falciparum after 60 years of chloroquine use. They provide additional field-based evidence for increased mefloquine susceptibility in pfmdr1 mutant P. falciparum and are suggestive of the intrahost selection of pfmdr1 mutant parasites.  相似文献   
86.
3D-ultrasound (US) imaging systems offer many advantages such as convenience, low operative costs and multiple scanning options. Most 3D-US freehand tracking systems are not optimally adapted for the quantification of lower limb arterial stenoses because their performance depends on the scanning length, on ferro-magnetic interferences or because they require a constant line of sight with the US probe. Robotic systems represent a promising alternative since they can control and standardize the 3D-US acquisition process for large scanning distances without requiring a specific line of sight. The performance of a new prototype medical robot, in terms of positioning and inter-target accuracies (i.e., difference between measurements and ground truth values) was evaluated with a lower-limb mimicking phantom throughout the robot workspace. The teach/replay repeatability (i.e., difference between taught and replayed points) was also assessed. A mean positioning accuracy between 0.46 mm and 0.75 mm was found on all scanning zones. The mean inter-target distance accuracy varied between 0.26 mm and 0.61 mm. Teach/replay repeatability below 0.20mm was also obtained. Additionally, a 3D reconstruction of in-vitro stenoses was performed with the robotic US scanner. The quantification error of a 80% area reduction (AR) stenosis was 3.0%, whereas it was -0.9% for a less severe 75% AR stenosis. Altogether, these results suggest that the robot may be of value for the clinical evaluation of lower limb vessels over long and tortuous segments starting from the iliac artery down to the popliteal artery below the knee.  相似文献   
87.
A preclinical canine model capable of predicting a compound's potential for a human food effect was developed. The beagle dog was chosen as the in vivo model. A validation set of compounds with known propensities for human food effect was studied. Several diets were considered including high-fat dog food and various quantities of the human FDA meal. The effect of pentagastrin pretreatment was also investigated. The high-fat dog food did not predict human food effect and was discontinued from further evaluation. The amount of FDA meal in the dog was important in the overall prediction of the magnitude of human food effect. Fed/fasted Cmax and AUC ratios using a 50-g aliquot of the FDA meal in the dog were in the closest qualitative agreement to human data. Pentagastrin pretreatment did not affect the AUC in the fed state, but increased the fasted AUC for weakly basic compounds. Pentagastrin pretreatment and a 50-g aliquot of the FDA meal in the dog predicted the human food effect for a validation set of compounds. This model, which is intended for compound screening, will be helpful for determining food effect as a liability when compounds progress from discovery to clinical development.  相似文献   
88.
This article presents a 17-year (1990–2006) retrospective summary of ongoing studies of occupational exposure to refractory ceramic fiber (RCF) in the United States. Beginning in 1990, RCF producers integrated and harmonized individual workplace monitoring programs to provide data useful for various longitudinal and cross-sectional analyses, benchmarking, and various technical analyses. For 10 of these 17 years, the program has been conducted in partnership with government agencies, first a 5-year (1993–1998) program with the U.S. Environmental Protection Agency and later another 5-year (2002–2006) program with the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health. This article updates earlier published studies and provides lessons to be learned in the design of industrial hygiene monitoring and control programs.  相似文献   
89.
90.
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