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   408篇
  免费   35篇
  443篇
  2024年   1篇
  2023年   4篇
  2022年   10篇
  2021年   15篇
  2020年   4篇
  2019年   16篇
  2018年   13篇
  2017年   11篇
  2016年   14篇
  2015年   19篇
  2014年   29篇
  2013年   27篇
  2012年   29篇
  2011年   33篇
  2010年   24篇
  2009年   16篇
  2008年   23篇
  2007年   27篇
  2006年   25篇
  2005年   17篇
  2004年   17篇
  2003年   7篇
  2002年   14篇
  2001年   5篇
  2000年   3篇
  1999年   2篇
  1998年   5篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1991年   1篇
  1989年   2篇
  1987年   2篇
  1984年   1篇
  1982年   1篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1963年   1篇
  1960年   2篇
  1957年   1篇
  1948年   1篇
  1947年   1篇
排序方式: 共有443条查询结果,搜索用时 10 毫秒
101.
Multiple studies demonstrate the influence of the limbic system on the processing of sensory events and attentional guidance. But the mechanisms involved therein are yet not entirely clear. The close connection of handling incoming sensory information and memory retrieval, like in the case of habituation towards insignificant stimuli, suggests a crucial impact of the hippocampus on the direction of attention. In this paper we thus present a neurofunctional forward model of a hippocampal comparator function based on the theory of theta-regulated attention. Subsequently we integrated this comparator model into a multiscale framework for the simulation of evoked responses. The results of our simulations were compared to experimental data on electroencephalographic (EEG) correlates of habituation towards familiar stimuli using time-scale analysis. In consequence we are able to present additional evidence for limbic influences on the direction of attention driven by stimulus novelty and a systems neuroscience framework for the statements given in the theta-regulated attention hypothesis.  相似文献   
102.
103.

Conservation programmes are always limited by available resources. Careful planning is therefore required to increase the efficiency of conservation and gap analysis can be used for this purpose. This method was used to assess the representativeness of current ex situ and in situ conservation actions of 234 priority crop wild relatives (CWR) in Indonesia. This analysis also included species distribution modelling, the creation of an ecogeographical land characterization map, and a complementarity analysis to identify priorities area for in situ conservation and for further collecting of ex situ conservation programmes. The results show that both current ex situ and in situ conservation actions are insufficient. Sixty-six percent of priority CWRs have no recorded ex situ collections. Eighty CWRs with ex situ collections are still under-represented in the national genebanks and 65 CWRs have no presence records within the existing protected area network although 60 are predicted to exist in several protected areas according to their potential distribution models. The complementarity analysis shows that a minimum of 61 complementary grid areas (complementary based on grid cells) are required to conserve all priority taxa and 40 complementary protected areas (complementary based on existing protected areas) are required to conserve those with known populations within the existing in situ protected area network. The top ten of complementary protected areas are proposed as the initial areas for the development of CWR genetic reserves network in Indonesia. It is recommended to enhanced coordination between ex situ and in situ conservation stakeholders for sustaining the long term conservation of CWR in Indonesia. Implementation of the research recommendations will provide for the first time an effective conservation planning of Indonesia’s CWR diversity and will significantly enhance the country’s food and nutritional security.

  相似文献   
104.
Salt stress decreases plant growth prior to significant ion accumulation in the shoot. However, the processes underlying this rapid reduction in growth are still unknown. To understand the changes in salt stress responses through time and at multiple physiological levels, examining different plant processes within a single set-up is required. Recent advances in phenotyping has allowed the image-based estimation of plant growth, morphology, colour and photosynthetic activity. In this study, we examined the salt stress-induced responses of 191 Arabidopsis accessions from 1 h to 7 days after treatment using high-throughput phenotyping. Multivariate analyses and machine learning algorithms identified that quantum yield measured in the light-adapted state (Fv′/Fm′) greatly affected growth maintenance in the early phase of salt stress, whereas the maximum quantum yield (QYmax) was crucial at a later stage. In addition, our genome-wide association study (GWAS) identified 770 loci that were specific to salt stress, in which two loci associated with QYmax and Fv′/Fm′ were selected for validation using T-DNA insertion lines. We characterized an unknown protein kinase found in the QYmax locus that reduced photosynthetic efficiency and growth maintenance under salt stress. Understanding the molecular context of the candidate genes identified will provide valuable insights into the early plant responses to salt stress. Furthermore, our work incorporates high-throughput phenotyping, multivariate analyses and GWAS, uncovering details of temporal stress responses and identifying associations across different traits and time points, which are likely to constitute the genetic components of salinity tolerance.  相似文献   
105.
Bacteria belonging to phylum Gemmatimonadetes comprise approximately 2% of soil bacterial communities. However, little is known of their ecology due to a lack of cultured representation. Here we present evidence from biogeographical analyses and seasonal quantification of Gemmatimonadetes in soils, which suggests an adaptation to low soil moisture.  相似文献   
106.
Vascular endothelial dysfunction occurs during the human aging process, and it is considered as a crucial event in the development of many vasculopathies. We investigated the underlying mechanisms of this process, particularly those related with oxidative stress and inflammation, in the vasculature of subjects aged 18–91 years without cardiovascular disease or risk factors. In isolated mesenteric microvessels from these subjects, an age‐dependent impairment of the endothelium‐dependent relaxations to bradykinin was observed. Similar results were observed by plethysmography in the forearm blood flow in response to acetylcholine. In microvessels from subjects aged less than 60 years, most of the bradykinin‐induced relaxation was due to nitric oxide release while the rest was sensitive to cyclooxygenase (COX) blockade. In microvessels from subjects older than 60 years, this COX‐derived vasodilatation was lost but a COX‐derived vasoconstriction occurred. Evidence for age‐related vascular oxidant and inflammatory environment was observed, which could be related to the development of endothelial dysfunction. Indeed, aged microvessels showed superoxide anions (O2?) and peroxynitrite (ONOO?) formation, enhancement of NADPH oxidase and inducible NO synthase expression. Pharmacological interference of COX, thromboxane A2/prostaglandin H2 receptor, O2?, ONOO?, inducible NO synthase, and NADPH oxidase improved the age‐related endothelial dysfunction. In situ vascular nuclear factor‐κB activation was enhanced with age, which correlated with endothelial dysfunction. We conclude that the age‐dependent endothelial dysfunction in human vessels is due to the combined effect of oxidative stress and vascular wall inflammation.  相似文献   
107.
108.
Plasmonics - Graphene plasmonics is one of the most explored fields since the successful experimental discovery of the graphene due to its unprecedented properties. The dynamical modulation and...  相似文献   
109.
Cluster Computing - Understanding flow traffic patterns in networks, such as the Internet or service provider networks, is crucial to improving their design and building them robustly. However, as...  相似文献   
110.
Molecular and Cellular Biochemistry - Epithelial-mesenchymal transition (EMT) leads to tumor dissemination and metastasis. Metadherin (MTDH) is an oncogene that plays an important role in...  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