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   332篇
  免费   20篇
电工技术   5篇
化学工业   75篇
金属工艺   2篇
机械仪表   4篇
建筑科学   18篇
矿业工程   1篇
能源动力   35篇
轻工业   20篇
水利工程   8篇
无线电   41篇
一般工业技术   35篇
冶金工业   8篇
原子能技术   1篇
自动化技术   99篇
  2024年   1篇
  2023年   6篇
  2022年   18篇
  2021年   17篇
  2020年   7篇
  2019年   16篇
  2018年   15篇
  2017年   17篇
  2016年   11篇
  2015年   11篇
  2014年   11篇
  2013年   24篇
  2012年   29篇
  2011年   38篇
  2010年   19篇
  2009年   23篇
  2008年   11篇
  2007年   22篇
  2006年   9篇
  2005年   2篇
  2004年   9篇
  2003年   7篇
  2002年   4篇
  2001年   5篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1997年   4篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1987年   1篇
  1979年   1篇
  1976年   4篇
排序方式: 共有352条查询结果,搜索用时 15 毫秒
231.
Perphosphorylated pentopyranoses and pentofuranoses were synthesized from parent carbohydrates as potential allosteric effectors of hemoglobin (Hb). The construction of seven- and eight-membered cyclic pyrophosphates was also carried out successfully on most of the pentoses. All final compounds were tested for their efficiency on oxygen release from human Hb. Most proved to be efficient allosteric effectors, some of them with an affinity toward Hb and an effect on oxygen release from Hb approaching that of myo-inositol hexakisphosphate, which is one of the most active allosteric effectors of Hb. The efficacy was higher for free phosphates than for pyrophosphates.  相似文献   
232.
The ever increasing adoption of field programmable devices in various application domains for building complex embedded systems based on FPGA processors along with the reliability issues having emerged for FPGA devices built with the latest nanometer technologies, have raised the need for new fault tolerant techniques in order to improve dependability and extend system lifetime. In addition, the runtime partial reconfiguration technology highly mature in the modern FPGA families along with the availability of unused programmable resources in most FPGA designs provide new and interesting opportunities to build advanced fault tolerance mechanisms. In this paper, we exploit the dynamic reconfiguration potential of today’s FPGA architectures and the advances in the related design support tools and we propose a fault-tolerant approach for FPGA embedded processors based on runtime partial reconfiguration. According to the proposed methodology, the processor core is partitioned into reconfigurable modules and each module is duplicated to implement a concurrent error detection mechanism. Precompiled configurations containing spare resources are generated for each duplicated module and are used to repair at runtime the defective modules. Also, a fault tolerance scheme for the proxy logic of the reconfigurable modules, which cannot move in the alternative configurations along with the rest logic, is proposed. Moreover, a compression method for the alternative partial bitstreams, which significantly reduces the high storage space requirements of the proposed approach, is presented. Two different hardware decompression schemes have been implemented in a Virtex-5 device and compared in terms of area overhead and decompression latency. Furthermore, a thorough examination has been performed, regarding how the percentage of the spare resources and their allocation in the reconfigurable regions affect the compression efficiency and the processor performance. Finally, the proposed approach has been demonstrated in three different components – ALU, multiplier-accumulator, and instruction-fetch unit – of an open-source embedded processor.  相似文献   
233.
Development of new embedded systems requires tuning of the software applications to specific hardware blocks and platforms as well as to the relevant input data instances. The behaviour of these applications heavily relies on the nature of the input data samples, thus making them strongly data-dependent. For this reason, it is necessary to extensively profile them with representative samples of the actual input data. An important aspect of this profiling is done at the dynamic data type level, which actually steers the designers choice of implementation of these data types. The behaviour of the applications is then characterized, through an analysis phase, as a collection of software metadata that can be used to optimize the system as a whole. In this paper we propose to represent the behaviour of data-dependent applications to enable optimizations, rather than to analyze their structure or to define the engineering process behind them. Moreover, we specifically limit ourselves to the scope of applications dominated by dynamically allocated data types running on embedded systems. We characterize the software metadata that these optimizations require, and we present a methodology, as well as appropriate techniques, to obtain this information from the original application. The optimizations performed on a complete case study, utilizing the extracted software metadata, achieve overall improvements of up to 42% in the number of cycles spent accessing memory when compared to code optimized only with the static techniques applied by GNU G++.  相似文献   
234.
235.
This study presents the results of the flow regime evaluation, by means of computational fluid dynamics (CFD), of a vegetated detention pond located at Waterlooville, Hampshire, UK. Alternative pond layouts were assessed for the same flow conditions on the basis of recommendations made in the literature. The results were validated by comparing the maximum computational velocities for the same case using different numbers of mesh elements. It was found that the development of a CFD model of detention ponds is intricate but feasible. The main findings were: (i) The present design performed well in terms of flood risk management, but the flow patterns could result in questionable treatment efficiency; (ii) vegetation seems to promote horizontal recirculation and turbulence; (iii) triangular and elliptical pond designs showed very poor performance; (iv) the most appropriate design for the given location and hydrological regime is an elliptical pond with a central emergent/submerged island.  相似文献   
236.
In this paper, we address the issue of nonlinear dimensionality reduction to efficiently index spectral audio similarity measures. We propose the embedding of the spectral similarity space to a low-dimensional Euclidean space. This guarantees the triangular inequality and allows the adoption of several indexing schemes. We enlighten the advantages of the proposed indexable method against recently proposed spectral similarity measures that are also indexable. Moreover, our method compares favorably to linear dimensionality reduction methods, like multidimensional scaling (MDS). The proposed method significantly reduces the computation time during the construction process compared to any audio measure and, simultaneously, minimizes the searching cost for similar songs. To the best of our knowledge, the important issue of audio similarity measures’ scalability is addressed for the first time.  相似文献   
237.
This study investigates the resource consumption of Japanese society since 1979 and its subsequent effects on the economic output of the nation and the environment. In order to quantify resource appropriation and trends in production and consumption, the concept of emergy synthesis is employed. Our results show a significant increase in the total amount of emergy consumed by 66.9% between 1979 and 2003 which comes hand in hand with an increase in the level of environmental stress by 93.7% (quantified as the environmental loading ratio). On the other hand the emergy required to produce 1 USD of economic output has been gradually decreasing which denotes an increase in the efficiency of the conversion of natural capital into economic output. What is most interesting though is the growing dependence of the Japanese economy on imported emergy, increasingly from developing nations, that severely affects the potential for unhindered economic growth. This can prove to be a big barrier that could affect the resource security of the Japanese economy and render it susceptible to risks associated with access to natural resources which in turn can jeopardise its long-term economic sustainability.  相似文献   
238.
239.
Seventy-eight limbs of forty-eight patients undergoing total hip replacement were studied by roentgenographic phlebography, cuff-impedance phlebography, and 125I fibrinogen scanning. Compared with roentgenographic phlebography, cuff-impedance phlebography detected seven of ten thrombi in the thigh but none of nine thrombi in the calf and popliteal veins, giving an over-all accuracy of 80 per cent. The 125I fibrinogen scanning technique detected none of the ten thrombi in the thigh and seven of the nine in the calf and popliteal veins, giving an over-all accuracy of 78 per cent. Combining the results of the two techniques, fourteen of the nineteen thrombi were detected. Cuff-impedance phlebography appears to be a useful method for the diagnosis of thrombi in the thigh after hip surgery.  相似文献   
240.
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