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   148篇
  免费   6篇
  2023年   1篇
  2022年   1篇
  2021年   3篇
  2020年   7篇
  2019年   1篇
  2018年   7篇
  2017年   3篇
  2016年   2篇
  2015年   8篇
  2014年   3篇
  2013年   9篇
  2012年   6篇
  2011年   7篇
  2010年   6篇
  2009年   6篇
  2008年   4篇
  2007年   7篇
  2006年   7篇
  2005年   5篇
  2004年   2篇
  2003年   8篇
  2002年   5篇
  2001年   5篇
  2000年   1篇
  1999年   3篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   3篇
  1980年   2篇
  1979年   6篇
  1978年   2篇
  1977年   3篇
  1974年   1篇
  1972年   1篇
  1970年   1篇
  1942年   2篇
排序方式: 共有154条查询结果,搜索用时 15 毫秒
81.
Competent social organisms will read the social signals of their peers. In primates, the face has evolved to transmit the organism''s internal emotional state. Adaptive action suggests that the brain of the receiver has co-evolved to efficiently decode expression signals. Here, we review and integrate the evidence for this hypothesis. With a computational approach, we co-examined facial expressions as signals for data transmission and the brain as receiver and decoder of these signals. First, we show in a model observer that facial expressions form a lowly correlated signal set. Second, using time-resolved EEG data, we show how the brain uses spatial frequency information impinging on the retina to decorrelate expression categories. Between 140 to 200 ms following stimulus onset, independently in the left and right hemispheres, an information processing mechanism starts locally with encoding the eye, irrespective of expression, followed by a zooming out to processing the entire face, followed by a zooming back in to diagnostic features (e.g. the opened eyes in “fear”, the mouth in “happy”). A model categorizer demonstrates that at 200 ms, the left and right brain have represented enough information to predict behavioral categorization performance.  相似文献   
82.
An integrative study of a meromictic lake ecosystem in Antarctica   总被引:1,自引:0,他引:1  
In nature, the complexity and structure of microbial communities varies widely, ranging from a few species to thousands of species, and from highly structured to highly unstructured communities. Here, we describe the identity and functional capacity of microbial populations within distinct layers of a pristine, marine-derived, meromictic (stratified) lake (Ace Lake) in Antarctica. Nine million open reading frames were analyzed, representing microbial samples taken from six depths of the lake size fractionated on sequential 3.0, 0.8 and 0.1 μm filters, and including metaproteome data from matching 0.1 μm filters. We determine how the interactions of members of this highly structured and moderately complex community define the biogeochemical fluxes throughout the entire lake. Our view is that the health of this delicate ecosystem is dictated by the effects of the polar light cycle on the dominant role of green sulfur bacteria in primary production and nutrient cycling, and the influence of viruses/phage and phage resistance on the cooperation between members of the microbial community right throughout the lake. To test our assertions, and develop a framework applicable to other microbially driven ecosystems, we developed a mathematical model that describes how cooperation within a microbial system is impacted by periodic fluctuations in environmental parameters on key populations of microorganisms. Our study reveals a mutualistic structure within the microbial community throughout the lake that has arisen as the result of mechanistic interactions between the physico-chemical parameters and the selection of individual members of the community. By exhaustively describing and modelling interactions in Ace Lake, we have developed an approach that may be applicable to learning how environmental perturbations affect the microbial dynamics in more complex aquatic systems.  相似文献   
83.
Abstract

Testing of an expanded, 800-compound set of analogues of the earlier described Strecker-type α-aminonitriles (selected from publicly available Enamine Ltd. Screening Collection) in thermal shift assay against bovine carbonic anhydrase (bCA) led to further validation of this new class of inhibitors and identification a new, refined chemotype represented by inhibitors with 10-improved potency.   相似文献   
84.
85.
ObjectiveThis study aimed to evaluate the serum level of netrin and soluble vascular cell adhesion molecule 1 (VCAM-I) in patients with type IΙ diabetes mellitus (T2DM) and evaluate the association of their levels with the development of a diabetic complication.Patients and methodsThis study was carried out on type II diabetic patients with and without complications and healthy individuals served as controls. All subjects were submitted to the estimation of serum lipid profile, serum creatinine, urinary albumin/creatinine ratio (ACR), fasting blood glucose (FBG), glycated hemoglobin (HbA1c), visceral adiposity index (VAI), atherogenic index of plasma (AIP), lipid accumulation product (LAP) and detection of serum level of netrin1 and VCAM1.ResultsDiabetic patients with complications had significantly higher serum levels of creatinine, ACR, cholesterol, Triglyceride, low-density lipoprotein, netrin1, and VCAM1 than diabetic patients without complications. Likewise, the level of VAI and LAP as markers of excessive body fat were significantly higher in diabetic patients with complications than diabetic patients without complications. The netrin1 and VCAM1 were a significant discriminator of T2DM renal complications with a sensitivity of 96%, 90%, and specificity of 82.7%, 91.3% respectively.ConclusionIt can be concluded that serum netrin1 and VCAM1 correlated significantly with markers of excessive body fat, a renal complication in the patient with type 2 diabetes mellitus.  相似文献   
86.
It is generally accepted that protein and solvation dynamics play fundamental roles in the mechanisms of protein-protein binding; however, assessing their contribution meaningfully has not been straightforward. Here, hydrogen/deuterium exchange mass spectrometry (H/D-Ex) was employed to assess the role of dynamics for a high-affinity human growth hormone variant (hGHv) and the wild-type growth hormone (wt-hGH) each binding to the extracellular domain of their receptor (hGHbp). Comparative analysis of the transient fluctuations in the bound and unbound states revealed that helix-1 of hGHv undergoes significant transient unfolding in its unbound state, a characteristic that was not found in wt-hGH or apparent in the temperature factor data from the X-ray analysis of the unbound hGHv structure. In addition, upon hormone binding, an overall increase in stability was observed for the beta-sheet structure of hGHbp which included sites distant from the binding interface. On the basis of the stability, binding kinetics, and thermodynamic data presented, the increase in the binding free energy of hGHv is primarily generated by factors that appear to increase the energy of the unbound state relative to the free energy of the bound complex. This implies that an alternate route to engineer new interactions aiming to increase protein-protein association energies may be achieved by introducing certain mutations that destabilize one of the interacting molecules without destabilizing the resulting bound complex. Importantly, although the hGHv molecule is less stable than its wt-hGH counterpart, its resulting active ternary complex with two copies of hGHbp has comparable stability to the wt complex.  相似文献   
87.
88.
A novel series of pyrrole inhibitors of MEK kinase has been developed using structure-based drug design. Optimization of the series led to the identification of potent inhibitors with good pharmaceutical properties.  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