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   290篇
  免费   21篇
电工技术   2篇
化学工业   119篇
金属工艺   1篇
机械仪表   3篇
建筑科学   11篇
矿业工程   1篇
能源动力   3篇
轻工业   41篇
水利工程   5篇
石油天然气   2篇
无线电   20篇
一般工业技术   54篇
冶金工业   25篇
自动化技术   24篇
  2024年   1篇
  2023年   5篇
  2022年   30篇
  2021年   17篇
  2020年   11篇
  2019年   9篇
  2018年   5篇
  2017年   10篇
  2016年   13篇
  2015年   14篇
  2014年   14篇
  2013年   22篇
  2012年   13篇
  2011年   15篇
  2010年   12篇
  2009年   12篇
  2008年   14篇
  2007年   16篇
  2006年   11篇
  2005年   7篇
  2004年   7篇
  2003年   13篇
  2002年   2篇
  2001年   6篇
  2000年   4篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1995年   4篇
  1994年   2篇
  1992年   2篇
  1991年   1篇
  1990年   3篇
  1989年   1篇
  1985年   2篇
  1982年   2篇
  1981年   2篇
  1979年   1篇
  1976年   2篇
排序方式: 共有311条查询结果,搜索用时 22 毫秒
31.
We present an application, and its development process, for interactive visual analysis of brain imaging data and clinical measurements. The application targets neuroscientists interested in understanding the correlations between active brain regions and physiological or psychological factors. The application has been developed in a participatory design process and has subsequently been released as the free software ‘VisualNeuro’. From initial observations of the neuroscientists' workflow, we concluded that while existing tools provide powerful analysis options, they lack effective interactive exploration requiring the use of many tools side by side. Consequently, our application has been designed to simplify the workflow combining statistical analysis with interactive visual exploration. The resulting environment comprises parallel coordinates for effective overview and selection, Welch's t-test to filter out brain regions with statistically significant differences and multiple visualizations for comparison between brain regions and clinical parameters. These exploration concepts enable neuroscientists to interactively explore the complex bidirectional interplay between clinical and brain measurements and easily compare different patient groups. A qualitative user study has been performed with three neuroscientists from different domains. The study shows that the developed environment supports simultaneous analysis of more parameters, provides rapid pathways to insights and is an effective tool for hypothesis formation.  相似文献   
32.
33.
The influence of an addition of either sand and/or spring-bloom algae on the efflux of nutrients from intact sediment cores from the Baltic Sea was studied in a flow-through experiment. The addition of sand significantly increased the efflux of silicon (Si) from sediment, but the algal addition did not. The effects on phosphorus (P) were not as clear, and fluxes of nitrogen (NH4 and NO2?+?3) remained relatively unaffected by the additions. The small effect of the algal addition was caused by the short time-period covered by the experiment and possibly by adsorption of released Si by the sediment. A follow-up bottle experiment showed that despite the apparently lower content of easily available Si and biogenic silica, BSi, in the sand, the sand-induced Si efflux was caused by release of Si from the sand itself, rather than by indirectly increasing the dissolution of BSi present in the sediment.  相似文献   
34.
Arundo donax has been recognized as a promising crop for biomass production on marginal lands due to its superior productivity and stress tolerance. However, salt stress negatively impacts A. donax growth and photosynthesis. In this study, we tested whether the tolerance of A. donax to salinity stress can be enhanced by the addition of 5-aminolevulinic acid (ALA), a known promoter of plant growth and abiotic stress tolerance. Our results indicated that root exposure to ALA increased the ALA levels in leaves along the A. donax plant profile. ALA enhanced Na+ accumulation in the roots of salt-stressed plants and, at the same time, lowered Na+ concentration in leaves, while a reduced callose amount was found in the root tissue. ALA also improved the photosynthetic performance of salt-stressed apical leaves by stimulating stomatal opening and preventing an increase in the ratio between abscisic acid (ABA) and indol-3-acetic acid (IAA), without affecting leaf methanol emission and plant growth. Supply of ALA to the roots reduced isoprene fluxes from leaves of non-stressed plants, while it sustained isoprene fluxes along the profile of salt-stressed A. donax. Thus, ALA likely interacted with the methylerythritol 4-phosphate (MEP) pathway and modulate the synthesis of either ABA or isoprene under stressful conditions. Overall, our study highlights the effectiveness of ALA supply through soil fertirrigation in preserving the young apical developing leaves from the detrimental effects of salt stress, thus helping of A. donax to cope with salinity and favoring the recovery of the whole plant once the stress is removed.  相似文献   
35.
36.
37.
用两种不同分子量的石蜡及一种微晶蜡掺和在沥青中,来研究蜡的性能(如分子量分布、平均分子量等)对沥青低温性能的影响.用Superpave沥青胶结料性能规范系统的BBR、DTT、临界龟裂温度(Tcritical)及玻璃转换温度(Tg)来研究掺有3%或6%蜡的沥青低温性能,低分子量及分子量分布窄的石蜡降低了沥青的DTT破坏应力,同时增加了正割模量(Secant Modulus)及BBR的热应力.微晶蜡对沥青的DTT破坏应力的影响比较少,并且不影响正割模量,但增加了BBR的热应力;但当将不同蜡的沥青混合,即将蜡的分子量分布扩大,则DTT破坏应力略为降低,正割模量不变,而BBR的热应力则减少.换言之,如果将含不同蜡的沥青混合,则蜡对沥青低温性能的影响降低,这会改善含蜡沥青的低温性能,原因可能是蜡的凝结受其分子量所影响,较宽的分子量分布会导致蜡在较宽的温度范围内慢慢凝结,缓和了蜡突然结晶对沥青低温性能的有害反应.  相似文献   
38.
The triple-transgenic mouse line (3×Tg-AD) harboring PS1M146V, APPSwe, and taup301L transgenes represents the only transgenic model for Alzheimer's disease (AD) to date capturing both β-amyloid and tau neuropathology. The present study provides an extensive behavioral characterization of the 3×Tg-AD mouse line, evaluating the emergence of noncognitive and cognitive AD-like symptoms at two ages corresponding to the early (6-7 months) and advanced (12-13 months) stages of AD-pathology. Enhanced responsiveness to aversive stimulation was detected in mutant mice at both ages: the 3×Tg-AD genotype enhanced acoustic startle response and facilitated performance in the cued-version of the water maze. These noncognitive phenotypes were accompanied by hyperactivity and reduced locomotor habituation in the open field at the older age. Signs of cognitive aberrations were also detected at both ages, but they were limited to associative learning. The present study suggests that this popular transgenic mouse model of AD has clear phenotypes beyond the cognitive domain, and their potential relationship to the cognitive phenotypes should be further explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
39.
The acceptance of, preference for and consumption intent for high‐fibre muffins and/or rusks baked with either red palm olein (RPO) or sunflower oil (SFO, as control) were evaluated by two consumer groups of 144 and 67 consumers, respectively, in order to determine the possibility of their successful inclusion as carriers for oils in a subsequent nutrition intervention trial. A five‐point hedonic and food action rating scale was used for sensory evaluation. SFO muffins and rusks scored significantly higher than RPO products on a number of hedonic dimensions and were thus more acceptable to the average consumer. Sensory attributes of SFO and RPO products received high scores by consumers from both groups (≥4.0 on five‐point scale), and consumers intended to eat them often (at least one per day). The RPO products were satisfactory in terms of acceptance and complied with requirements for use in the subsequent nutrition intervention trial.  相似文献   
40.
With a view to ascertaining the possible role of water content of the cells in the reported elevated values for proton spin-lattice relaxation time (T1) in malignant tissues, measurements of percent water content as well as T1 were undertaken in 68 cases of normal and concerous tissues from diverse sites in human patients. T1 values for the uninvolved samples were found to lie in the range of 400-1000 msec while the corresponding range for the involved samples was from 450-1520 msec. Water content of both normal and uninvolved tissues mostly lay in the narrow range of 70-90%. Occasionally samples with large T1 values showed lower water content as well. Data obtained weakens the case for characterization of tumor cells on the basis of their water content alone.  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