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   1051篇
  免费   28篇
  国内免费   7篇
电工技术   22篇
综合类   2篇
化学工业   157篇
金属工艺   22篇
机械仪表   13篇
建筑科学   118篇
矿业工程   2篇
能源动力   50篇
轻工业   80篇
水利工程   17篇
石油天然气   6篇
武器工业   1篇
无线电   68篇
一般工业技术   135篇
冶金工业   125篇
原子能技术   4篇
自动化技术   264篇
  2024年   2篇
  2023年   5篇
  2022年   14篇
  2021年   30篇
  2020年   9篇
  2019年   23篇
  2018年   23篇
  2017年   13篇
  2016年   34篇
  2015年   19篇
  2014年   26篇
  2013年   91篇
  2012年   71篇
  2011年   80篇
  2010年   61篇
  2009年   63篇
  2008年   61篇
  2007年   58篇
  2006年   57篇
  2005年   35篇
  2004年   25篇
  2003年   31篇
  2002年   35篇
  2001年   25篇
  2000年   9篇
  1999年   24篇
  1998年   29篇
  1997年   16篇
  1996年   14篇
  1995年   15篇
  1994年   19篇
  1993年   11篇
  1992年   8篇
  1991年   7篇
  1990年   10篇
  1989年   3篇
  1988年   4篇
  1987年   3篇
  1986年   2篇
  1985年   7篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1979年   3篇
  1977年   4篇
  1974年   1篇
  1969年   1篇
  1966年   1篇
排序方式: 共有1086条查询结果,搜索用时 9 毫秒
71.
The primary objective of this research was to determine the optimal hyperspectral wavelengths based on spectroscopy data over the spectral range of 450–2500 nm for the detection of the invasive species Lantana camara L. (lantana) from seven of its co-occurring species. A procedure based on statistical analysis of the reflectance and the first derivative reflectance (FDR) identified 86 and 18 bands, respectively, where lantana significantly differed from its co-occurring species. The effectiveness of the identified optimal bands was then evaluated using Hyperion imagery. The original Hyperion image with 155 bands gave an overall accuracy of 80% compared to 77% and 76% from the 86- and 18-band spectral subsets, respectively. A pairwise comparison of the three error matrices showed no significant difference in the accuracy achieved. The FDR analysis combined with the statistical analysis proved to be a useful procedure for data reduction by refining the discrimination to fewer optimal bands for lantana detection with no adverse impact on classification accuracy.  相似文献   
72.
Four experiments investigated the effect of recent selective practice on the cost of switching between 2 tasks afforded by letter-digit pairs: alphabet arithmetic and shape comparison. Experiments 1 and 2 found a greater cost associated with switching to the more recently practiced task: evidence that task-set inertia contributes to switching costs. Experiment 3 found this effect to be limited to trials on which a recently trained stimulus followed another such stimulus: a result problematic for all current theories of task-set priming. Experiment 4 showed that the effect of recent practice was eliminated by active preparation for a task switch: It appears that endogenous task-set preparation reduces the effects of task-set inertia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
73.
Chlorination of drinking water in the presence of bromide and dissolved organic carbon (DOC) leads to the formation of brominated and chlorinated disinfection by-products (DBP). The concentration of bromide ions in the raw water is a significant factor in the speciation of DBP formed, and causes shifts in trihalomethane (THM) formation from chlorinated to brominated species. Drinking water treatment techniques that remove organic contaminants without affecting bromide ion concentrations cause increases in the brominated THM. For the present study, three water supplies containing different DOC and ambient bromide concentrations were filtered through biologically assisted granular activated carbon (BGAC). Similar to adsorption and coagulation treatment, this treatment does not remove bromide from drinking water; also, THMFP (trihalomethane formation potential) analysis indicated that the chlorinated effluent contained higher concentrations of brominated THM in comparison to the influent. Although BGAC may increase the brominated THM, which may be more toxic than the chlorinated THM, the overall reduction of THMFP by DOC removal far exceeds this negative change, thereby producing a much less toxic finished drinking water. This work is part of a study to make high DOC surface waters on the Canadian prairie safe and palatable for small volume users (individuals or small communities).  相似文献   
74.
75.
It has been reported that it is harder to switch to a strong, well-practiced task from a weaker, less-practiced task than vice versa. Three experiments replicated this surprising asymmetry and investigated how it is affected by a reduction in interference between tasks. Experiment 1 progressively delayed the onset of the stimulus attribute associated with the stronger task. Experiments 2 and 3 separated the response sets of the tasks. Both manipulations reduced, without eliminating, interference of the stronger with the weaker task but reversed the asymmetry of switch costs, resulting in a larger cost of switching to the weaker task. The results are interpreted in terms of a model of the interactions between control input, task strength, and task priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
76.
We present a generalized exposure assessment of 28 disposal options for poultry carcasses in the event of a highly pathogenic avian influenza (HPAI) outbreak. The analysis supports a hereto unverified disposal hierarchy for animal carcasses, placing waste processing (e.g., incineration and rendering) above controlled disposal (e.g., landfill), above uncontrolled disposal (e.g., burial on-farm). We illustrate that early stages of the disposal chain (on-farm) pose greater opportunities for exposure to hazardous agents than later stages, where agents are generally contained, wastes are treated, and residues are managed by regulated processes. In selecting carcass disposal options, practitioners are advised to consider the full range of hazards rather than focusing solely on the HPAI agent, and to give preference to technologies that (i) offer high destruction efficiencies for target pathogens; (ii) do not give rise to significant releases of other pathogenic organisms; and (iii) do not release unacceptable concentrations of toxic chemicals. The approach offers an exposure assessment perspective for carcass disposal, thus providing a risk-informed basis for contingency planning and operational intervention. The authors recognize that relevant legislation, public perception, available capacity, and cost also need to be considered when selecting disposal options in the event of HPAI.  相似文献   
77.
This work addresses the challenge of creating virtual agents that are able to portray culturally appropriate behavior when interacting with other agents or humans. Because culture influences how people perceive their social reality it is important to have agent models that explicitly consider social elements, such as existing relational factors. We addressed this necessity by integrating culture into a novel model for simulating human social behavior. With this model, we operationalized a particular dimension of culture—individualism versus collectivism—within the context of an interactive narrative scenario that is part of an agent-based tool for intercultural training. Using this scenario we conducted a cross-cultural study in which participants from a collectivistic country (Portugal) were compared with participants from an individualistic country (the Netherlands) in the way they perceived and interacted with agents whose behavior was either individualistic or collectivistic, according to the configuration of the proposed model. In the obtained results, Portuguese subjects rated the collectivistic agents more positively than the Dutch but both countries had a similarly positive opinion about the individualistic agents. This experiment sheds new light on how people from different countries differ when assessing the social appropriateness of virtual agents, while also raising new research questions on this matter.  相似文献   
78.
Cancer cachexia is a common condition in many cancer patients, particularly those with advanced disease. Cancer cachexia patients are generally less tolerant to chemotherapies and radiotherapies, largely limiting their treatment options. While the search for treatments of this condition are ongoing, standards for the efficacy of treatments have yet to be developed. Current diagnostic criteria for cancer cachexia are primarily based on loss of body mass and muscle function. However, these criteria are rather limiting, and in time, when weight loss is noticeable, it may be too late for treatment. Consequently, biomarkers for cancer cachexia would be valuable adjuncts to current diagnostic criteria, and for assessing potential treatments. Using high throughput methods such as “omics approaches”, a plethora of potential biomarkers have been identified. This article reviews and summarizes current studies of biomarkers for cancer cachexia.  相似文献   
79.
This paper describes an efficient technique for the design of fault-secure VLSI circuits based on differential cascode voltage switch (DCVS) logic. We propose a new synthesis method for constructing DCVS circuits with a near-optimal transistor count based on binary decision diagrams (BDDs). the time and memory resources required are very low, making the technique practical even for PC-based synthesis tools. This method is the basis for a CAD tool that allows automatic synthesis of fault-secure circuits based on the DCVS technology. We finally present an improved design and implementation of a 2's complement serial/parallel multiplier as an application of the proposed technique and algorithm.  相似文献   
80.
Efforts to stimulate reinvestment in the private rented sector in Britain began in the late 1980s. It suited the Conservative government to label these changes as ‘deregulation’ although they were more complex than this term implies. This article provides evidence of the impacts of the changes in Scotland. It emphasizes the need to examine the impacts on different groups within the private rented sector. In particular, deregulation tended to favour those able to pay market rents, while increased restrictions on housing benefits meant that the ability of low-income households to afford private rented accommodation was reduced. Other groups, such as those in tied accommodation or on regulated tenancies, were largely unaffetted by the changes. In response to deregulation, there has been a significant increase in the flow of lets at the upper end of the market (self-contained flats and houses) while rents for this type of accommodation have barely risen. At the lower end of the market (shared accommodation), the flow of lets has increased only marginally or not at all. Landlords also appear to have become more reluctant to house low-income tenants. The article uses a database compiled from advertisements for private rented accommodation appearing in newspapers and property guides in the period 1987 to 1996. Nick Bailey is a Research Fellow in the Department of Urban Studies at the University of Glasgow. His main research interests include: housing and urban policy, particularly housing renewal, neighbourhood regeneration and the private housing market; urban economic and social change; and local economic development policies.  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