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   2710篇
  免费   167篇
  国内免费   3篇
电工技术   32篇
综合类   5篇
化学工业   735篇
金属工艺   38篇
机械仪表   49篇
建筑科学   115篇
矿业工程   10篇
能源动力   105篇
轻工业   200篇
水利工程   29篇
石油天然气   5篇
无线电   244篇
一般工业技术   497篇
冶金工业   194篇
原子能技术   9篇
自动化技术   613篇
  2024年   4篇
  2023年   31篇
  2022年   107篇
  2021年   136篇
  2020年   81篇
  2019年   83篇
  2018年   102篇
  2017年   84篇
  2016年   105篇
  2015年   89篇
  2014年   118篇
  2013年   195篇
  2012年   146篇
  2011年   228篇
  2010年   144篇
  2009年   143篇
  2008年   175篇
  2007年   125篇
  2006年   111篇
  2005年   75篇
  2004年   56篇
  2003年   62篇
  2002年   43篇
  2001年   31篇
  2000年   35篇
  1999年   30篇
  1998年   55篇
  1997年   56篇
  1996年   38篇
  1995年   28篇
  1994年   25篇
  1993年   16篇
  1992年   11篇
  1991年   8篇
  1990年   6篇
  1989年   13篇
  1988年   15篇
  1987年   9篇
  1986年   3篇
  1985年   10篇
  1984年   5篇
  1983年   6篇
  1982年   7篇
  1981年   3篇
  1980年   4篇
  1978年   4篇
  1977年   6篇
  1976年   2篇
  1975年   3篇
  1974年   3篇
排序方式: 共有2880条查询结果,搜索用时 328 毫秒
101.
This study examined how response mapping of features within single- and multiple-feature targets affects decision-based processing and attentional capacity demands. Observers judged the presence or absence of 1 or 2 target features within an object either presented alone or with distractors. Judging the presence of 2 features relative to the less discriminable of these features alone was faster (conjunction benefits) when the task-relevant features differed in discriminability and were consistently mapped to responses. Conjunction benefits were attributed to asynchronous decision priming across attended, task-relevant dimensions. A failure to find conjunction benefits for disjunctive conjunctions was attributed to increased memory demands and variable feature-response mapping for 2- versus single-feature targets. Further, attentional demands were similar between single- and 2-feature targets when response mapping, memory demands, and discriminability of the task-relevant features were equated between targets. Implications of the findings for recent attention models are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
102.
Nitric oxide (NO) is a gaseous intercellular messenger with a wide range of neural functions. NO is synthesized by activation of different isoforms of nitric oxide synthases (NOS). At present NOS immunoreactivity has been described in mouse brain in restricted and definite areas and no detailed mapping studies have yet been reported for NOS immunoreactivity. We have studied the distribution of neuronal NOS-containing neurons in the brain of three months male mice, using a specific commercial polyclonal antibody against the neuronal isoform of nitric oxide synthase (nNOS). Neuronal cell bodies exhibiting nNOS immunoreactivity were found in several distinct nuclei throughout the brain. The neurons that were positively stained exhibited different intensities of reaction. In some brain areas (i.e., cortex, striatum, tegmental nuclei) neurons were intensely stained in a Golgi-like fashion. In other regions, immunoreactive cells are moderately stained (i.e., magnocellular nucleus of the posterior commissure, amygdaloid nucleus, interpeduncular nucleus, lateral periaqueductal gray) or weakly stained (i.e., vascular organ of the lamina terminalis, hippocampus, inferior colliculus, reticular nucleus). In the mouse, the NO-producing system appears well developed and widely diffused. In particular, nNOS immunoreactive neurons seem chiefly present in several sensory pathways like all the nuclei of the olfactory system, as well as in many regions of the lymbic system. These data suggest a widespread role for the NO system in the mouse nervous system.  相似文献   
103.
A solvent vapor treatment was applied to femtosecond-laser-ablated microchannels in PMMA to selectively restore the original hydrophilic wetting behavior of the pristine surface. The hydrophobic surface of the microchannels from the submicron porosity induced by ablation becomes smoother and more transparent after the treatment. This simple and low-cost method, together with suitable masking, can produce wettability patterns that may be exploited to develop passive microfluidic elements such as valves and mixers.  相似文献   
104.
The paper presents results from social network analysis applied to data on patenting of academics inventors employed in two Italian universities (Trieste University and Udine university, both located in Friuli Venezia Giulia region). The aim is to compare the co-invention networks generated by the academic inventors, tenured by one of the two universities, in their patenting activity with several organisations—firms, public research organisations—and in their activity for patents owned by one of the two universities. Results show that, despite the structural similarity, non-marginal differences emerge in the interaction of the two forms of patenting across the two universities. Empirical evidence suggests new research questions related in particular to the role played by the differing university patenting strategies in shaping local networks.  相似文献   
105.
Not all of the issues impacting the success of tuberculosis (TB) treatment arise from pathogen-related disease characteristics. Nowadays, there is an increasing awareness that antibiotic treatment is not the only answer to the TB problem, promoting the search for alternative administration strategies and host-directed therapies. Among all the administration routes, being the lungs the main TB focus, inhalation is conceptually a logical solution to enhance treatment effectiveness and compliance. Nevertheless, research efforts and funding are almost entirely conveyed to conventional approaches. This review will critically evaluate the reasons constraining research in this field, providing some future perspectives. The most recent advances in inhalation approaches for TB will be discussed, either at the preclinical or clinical phase, illustrating the risk of failure and chances of success.  相似文献   
106.
Nowadays, the focus on the building energy consumption in the use phase prevails over an interest concerning the energy impacts linked to all the other phases of the construction process. However, reducing operational energy could lead to shifting the impacts from one stage to another. Thus, combining the study of strategies improving energy efficiency in the use phase with a life cycle approach is crucial. Exhibition halls are peculiar buildings from the geometry, construction and use points of view, rarely addressed in energy and life cycle energy analysis studies. Therefore, in this paper, a representative hall of the Milan Trade Fair is taken as a case study. A building energy simulation model is firstly calibrated in order to derive the operational energy for climatisation. The operational energy appears artificially low due to the short use period during the year. When compared with the calculated embodied energy of the envelope and structure, it is found that 57 years would be needed to balance energy spent in the construction and in the use phase. Further, some retrofit interventions are proposed and analyzed. Insulation interventions are not attractive from the economic payback time point of view. However, when the embodied energy of the retrofit interventions is compared with the energy savings in the use phase, interesting energy payback times are obtained. Therefore, this study puts in evidence on the importance of adopting a life cycle perspective, especially for buildings with low-intensity use. Eventually, the critical issues of the life cycle energy analysis are deeply discussed.  相似文献   
107.
Genetic programming researchers have shown a growing interest in the study of gene regulatory networks in the last few years. Our team has also contributed to the field, by defining two systems for the automatic reverse engineering of gene regulatory networks called GRNGen and GeNet. In this paper, we revise this work by describing in detail the two approaches and empirically comparing them. The results we report, and in particular the fact that GeNet can be used on large networks while GRNGen cannot, encourage us to pursue the study of GeNet in the future. We conclude the paper by discussing the main research directions that we are planning to investigate to improve GeNet.  相似文献   
108.
109.
Testing accounts for a relevant part of the production cost of complex or critical software systems. Nevertheless, time and resources budgeted to testing are often underestimated with respect to the target quality goals. Test managers need engineering methods to perform appropriate choices in spending testing resources, so as to maximize the outcome. We present a method to dynamically allocate testing resources to software components minimizing the estimated number of residual defects and/or the estimated residual defect density. We discuss the application to a real-world critical system in the homeland security domain. We describe a support tool aimed at easing industrial technology transfer by hiding to practitioners the mathematical details of the method application.  相似文献   
110.
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