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   390篇
  免费   17篇
  国内免费   1篇
电工技术   7篇
化学工业   115篇
金属工艺   6篇
机械仪表   11篇
建筑科学   10篇
能源动力   28篇
轻工业   23篇
水利工程   5篇
无线电   26篇
一般工业技术   106篇
冶金工业   8篇
原子能技术   3篇
自动化技术   60篇
  2024年   5篇
  2023年   10篇
  2022年   18篇
  2021年   17篇
  2020年   20篇
  2019年   7篇
  2018年   26篇
  2017年   26篇
  2016年   29篇
  2015年   13篇
  2014年   13篇
  2013年   37篇
  2012年   27篇
  2011年   47篇
  2010年   11篇
  2009年   16篇
  2008年   19篇
  2007年   7篇
  2006年   11篇
  2005年   3篇
  2004年   6篇
  2003年   3篇
  2002年   2篇
  2000年   7篇
  1997年   1篇
  1995年   3篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   3篇
排序方式: 共有408条查询结果,搜索用时 15 毫秒
21.
Neurodegenerative disorders are primarily characterized by neuron loss. The most common neurodegenerative disorders include Alzheimer’s and Parkinson’s disease. Although there are several medicines currently approved for managing neurodegenerative disorders, a large majority of them only help with associated symptoms. This lack of pathogenesis-targeting therapies is primarily due to the restrictive effects of the blood–brain barrier (BBB), which keeps close to 99% of all “foreign substances” out of the brain. Since their discovery, nanoparticles have been successfully used for targeted delivery into many organs, including the brain. This review briefly describes the pathophysiology of Alzheimer’s, Parkinson’s disease, and amyotrophic lateral sclerosis, and their current management approaches. We then highlight the major challenges of brain-drug delivery, followed by the role of nanotherapeutics for the diagnosis and treatment of various neurological disorders.  相似文献   
22.
23.
24.
The increasing industrialization and motorization of the world has led to a steep rise for the demand of petroleum-based fuels. Petroleum-based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain regions of the world. Therefore, those countries not having these resources are facing energy/foreign exchange crisis, mainly due to the import of crude petroleum. Hence, it is necessary to look for alternative fuels which can be produced from resources available locally within the country such as alcohol, biodiesel, vegetable oils etc. This paper reviews the production, characterization and current statuses of vegetable oil and biodiesel as well as the experimental research work carried out in various countries. This paper touches upon well-to-wheel greenhouse gas emissions, well-to-wheel efficiencies, fuel versatility, infrastructure, availability, economics, engine performance and emissions, effect on wear, lubricating oil etc.  相似文献   
25.
The metaphor of black swan refers to unpredictable events like 9/11, the Indian Ocean tsunami, or the Oklahoma City Federal Building bombing, that cause catastrophic consequences for structural system safety. The likelihood of occurrence for such unforeseen events cannot be estimated from the observed data or prognosticated by experts. The absence of event and likelihood information renders futile the application of usual risk-based methods for design. Therefore, a shift from the probabilistic approach to consequence-based structural design is necessary for coping with the unexpected demands. This is accomplished through the conceptual development of a system capacity oriented design approach, where structural members are designed for variable reliabilities based upon their contribution to causing adverse system consequences. Information about general structural integrity encoded in the stiffness matrix is applied, using member consequence factors ranging from 0 to 1, for determining a member’s contribution towards system response. The structural system is designed using member consequence factors as additional partial factors on the resistance side of the design equations. The consequence-based scheme does not need a triggering hazard event (or its likelihood) and is an apt structural design approach for black swan events.  相似文献   
26.
27.
As part of broader effort to synthesize a new class of water-based composite, hybrid emulsion polymerization was carried out with acrylic monomers [methyl methacrylate (MMA), n-butyl acrylate (BA)]. Nanocomposite of P(MMA–BA)/nano CaCO3 was synthesized by in situ emulsion polymerization. Water-based alkyd coating with various proportions nano CaCO3, P(MMA–BA) and its nanocomposite was formulated. Extent of polymerization with and without nano CaCO3 was measured using gravimetric method. Thermal properties of neat polymer, nanocomposite and coating films were evaluated by TGA and DSC, DTA analysis. Uniform dispersion of nano CaCO3 in polymer matrix was ensured from SEM/TEM images. Incorporation of nanoparticles to hybrid polymer and nanocomposite to alkyd emulsion showed significant enhancement in mechanical and thermal properties. Dual role of nanocomposite in coating; as a partial binder and a filler to improve property profile of neat coating has been reported.  相似文献   
28.
Large-scale distributed shared-memory multiprocessors (DSMs) provide a shared address space by physically distributing the memory among different processors. A fundamental DSM communication problem that significantly affects scalability is an increase in remote memory latency as the number of system nodes increases. Remote memory latency, caused by accessing a memory location in a processor other than the one originating the request, includes both communication latency and remote memory access latency over I/O and memory buses. The proposed architecture reduces remote memory access latency by increasing connectivity and maximizing channel availability for remote communication. It also provides efficient and fast unicast, multicast, and broadcast capabilities, using a combination of aggressively designed multiplexing techniques. Simulations show that this architecture provides excellent interconnect support for a highly scalable, high-bandwidth, low-latency network.  相似文献   
29.
The paper presents the γ-δ Routh approximation for interval systems. The interval γs and δs are evaluated for the higher order interval systems, and then an rth-order approximant is obtained by retaining the first r, interval δs, and γs. A numerical example illustrates the procedure  相似文献   
30.
Abstract

The visual perception of eyewitness plays a vital role in criminal identification scenario. It helps law enforcement authorities in searching particular criminal from their previous record. It has been reported that searching a criminal record manually requires too much time to get the accurate result. We have proposed a query-based approach which minimises the computational cost along with the reduction of search space. A symbolic database has been created to perform a stringent analysis on 150 public (Bollywood celebrities and Indian cricketers) and 90 local faces (our data-set). An expert knowledge has been captured to encapsulate every criminal’s anatomical and facial attributes in the form of symbolic representation. A fast query-based searching strategy has been implemented using dynamic decision tree data structure which allows four levels of decomposition to fetch respective criminal records. Two types of case studies - viewed and forensic sketches have been considered to evaluate the strength of our proposed approach. We have derived 1200 views of the entire population by taking into consideration 80 participants as eyewitness. The system demonstrates an accuracy level of 98.6% for test case I and 97.8% for test case II. It has also been reported that experimental results reduce the search space up to 30 most relevant records.  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