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   149篇
  免费   7篇
  2023年   2篇
  2021年   5篇
  2020年   2篇
  2019年   3篇
  2018年   4篇
  2017年   1篇
  2016年   6篇
  2015年   11篇
  2014年   7篇
  2013年   14篇
  2012年   21篇
  2011年   13篇
  2010年   16篇
  2009年   4篇
  2008年   6篇
  2007年   9篇
  2006年   8篇
  2005年   2篇
  2004年   6篇
  2003年   7篇
  2002年   1篇
  1996年   1篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1984年   2篇
  1983年   1篇
  1979年   1篇
排序方式: 共有156条查询结果,搜索用时 15 毫秒
151.
152.
Visual evoked potential parameters (latencies, intervals of latencies and amplitudes) obtained by photic stimulation using a light-emitting diode implanted in the frontal sinus of cats were studied by statistical methods (analysis of variance) during the stages of wakefulness, slow sleep and paradoxical sleep. The results show: a) greater intraindividual homogeneity in all cases with special emphasis on the latencies; b) the greatest homogeneity of responses was found during slow sleep and paradoxical sleep stages; c) in relation to the influences exerted by the sleep-wakefulness cycle on the visual evoked potentials, the parameters most affected were those closely related to the secondary complex. We conclude, that latency, due to its great homogeneity, is the most useful parameter in this kind of experiments and secondly, that it is the secondary complex of the visual evoked potentials that is affected by the endogenous conditions of the subject (in our case the sleep-wakefulness cycle stage).  相似文献   
153.
Many skin diseases are defined by the presence of neutrophils, which are among the first cells to respond to infection and inflammation. Currently, neutrophil identification in the skin is costly and slow. The objectives of the present work are to investigate the feasibility of detecting the presence of neutrophils in live skin microsamples using chemiluminescence and develop a device and procedures that will enable preclinical and clinical investigations. Our approach consists of collecting skin microsamples and exposing them to reagents that activate neutrophils and amplify the light emission produced by chemiluminescence. Experiments using live pig skin with and without inflammation show that it is feasible to detect the presence of neutrophils in the skin. The proposed method is minimally invasive, simple, fast, and does not require user specialization. The developed system is compact in size with a small footprint, which makes it portable and suitable for point‐of‐care diagnostics.  相似文献   
154.
This study investigated the rate of human papillomavirus (HPV) persistence, associated risk factors, and predictors of cytological alteration outcomes in a cohort of human immunodeficiency virus-infected pregnant women over an 18-month period. HPV was typed through L1 gene sequencing in cervical smears collected during gestation and at 12 months after delivery. Outcomes were defined as nonpersistence (clearance of the HPV in the 2nd sample), re-infection (detection of different types of HPV in the 2 samples), and type-specific HPV persistence (the same HPV type found in both samples). An unfavourable cytological outcome was considered when the second exam showed progression to squamous intraepithelial lesion or high squamous intraepithelial lesion. Ninety patients were studied. HPV DNA persistence occurred in 50% of the cases composed of type-specific persistence (30%) or re-infection (20%). A low CD4+T-cell count at entry was a risk factor for type-specific, re-infection, or HPV DNA persistence. The odds ratio (OR) was almost three times higher in the type-specific group when compared with the re-infection group (OR = 2.8; 95% confidence interval: 0.43-22.79). Our findings show that bonafide (type-specific) HPV persistence is a stronger predictor for the development of cytological abnormalities, highlighting the need for HPV typing as opposed to HPV DNA testing in the clinical setting.  相似文献   
155.
156.
Canola and oat forage potential may be affected by climatic conditions when sown early. The objective of this study was to evaluate the forage canola and oat potential in four early sowing dates (September 11 and 25; October 9 and 23) during the 2012-2013 and 2013-2014 cycles in Matamoros, Coahuila, Mexico. Growth cycle duration, chemical composition, dry matter (DM), crude protein (CP), and net energy for lactation (NEL) yields were determined. High temperatures and long photoperiods affected crops seeded on September 11, accelerating growth and reducing canola (26.6%-31.7%) and oat (15.8%) DM yields. As of September 25, canola cv IMC 205 reached DM yields (7746 kg ha-1 -9276 kg ha-1 ) similar to those obtained by oat (8115 kg ha-1 -9507 kg ha-1 ), while canola cv Hyola 401 obtained such yields only until October 23. Canola chemical composition was better than that found in oat, with higher CP, but lower acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents. Canola equaled oat CP yields (972 kg ha-1 -1215 kg ha-1 ) in the first sowing date, while in the other three other canola sowings reached higher yields (1193 kg ha-1 -1889 kg ha-1 ). As for NEL yields, no difference was observed between both species. The best sowing date for canola is from September 25 on, with CP production advantages over oat.  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