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   2669篇
  免费   34篇
  国内免费   12篇
电工技术   33篇
化学工业   125篇
金属工艺   14篇
机械仪表   24篇
建筑科学   6篇
能源动力   24篇
轻工业   38篇
水利工程   16篇
石油天然气   3篇
无线电   59篇
一般工业技术   142篇
冶金工业   2088篇
自动化技术   143篇
  2023年   14篇
  2022年   21篇
  2021年   23篇
  2020年   25篇
  2019年   18篇
  2018年   33篇
  2017年   23篇
  2016年   29篇
  2015年   33篇
  2014年   28篇
  2013年   48篇
  2012年   35篇
  2011年   29篇
  2010年   29篇
  2009年   37篇
  2008年   24篇
  2007年   20篇
  2006年   19篇
  2005年   16篇
  2004年   14篇
  2003年   18篇
  2002年   12篇
  2001年   12篇
  2000年   11篇
  1999年   64篇
  1998年   613篇
  1997年   419篇
  1996年   257篇
  1995年   150篇
  1994年   117篇
  1993年   129篇
  1992年   14篇
  1991年   25篇
  1990年   15篇
  1989年   23篇
  1988年   33篇
  1987年   21篇
  1986年   16篇
  1985年   11篇
  1984年   5篇
  1983年   3篇
  1982年   10篇
  1981年   19篇
  1980年   18篇
  1979年   5篇
  1978年   5篇
  1977年   47篇
  1976年   116篇
  1970年   3篇
  1969年   2篇
排序方式: 共有2715条查询结果,搜索用时 62 毫秒
91.
Conventional derivative based learning rule poses stability problem when used in adaptive identification of infinite impulse response (IIR) systems. In addition the performance of these methods substantially deteriorates when reduced order adaptive models are used for such identification. In this paper the IIR system identification task is formulated as an optimization problem and a recently introduced cat swarm optimization (CSO) is used to develop a new population based learning rule for the model. Both actual and reduced order identification of few benchmarked IIR plants is carried out through simulation study. The results demonstrate superior identification performance of the new method compared to that achieved by genetic algorithm (GA) and particle swarm optimization (PSO) based identification.  相似文献   
92.
93.
94.
Designing text-to-speech systems capable of producing natural sounding speech segments in different Indian languages is a challenging and ongoing problem. Due to the large number of possible pronunciations in different Indian languages, a number of speech segments are needed to be stored in the speech database while a concatenative speech synthesis technique is used to achieve highly natural speech segments. However, the large speech database size makes it unusable for small hand held devices or human computer interactive systems with limited storage resources. In this paper, we proposed a fraction-based waveform concatenation technique to produce intelligible speech segments from a small footprint speech database. The results of all the experiments performed shows the effectiveness of the proposed technique in producing intelligible speech segments in different Indian languages even with very less storage and computation overhead compared to the existing syllable-based technique.  相似文献   
95.
Parallel algorithms for several common problems such as sorting and the FFT involve a personalized exchange of data among all the processors. Past approaches to doing complete exchange have taken one of two broad approaches: direct exchange or the indirect message-combining approaches. While combining approaches reduce the number of message startups, direct exchange minimizes the volume of data transmitted. This paper presents a family of hybrid algorithms for wormhole-routed 2D meshes that can effectively utilize the complementary strengths of these two approaches to complete exchange. The performance of hybrid algorithms using Cyclic Exchange and Scott's Direct Exchange are studied using analytical models, simulation, and implementation on a Cray T3D system. The results show that hybrids achieve lower completion times than either pure algorithm for a range of mesh sizes, data block sizes, and message startup costs. It is also demonstrated that barriers may be used to enhance performance by reducing message contention, whether or not the target system provides hardware support for barrier synchronization. The analytical models are shown useful in selecting the optimum hybrid for any given combination of system parameters (mesh size, message startup time, flit transfer time, and barrier cost) and the problem parameter (data block size)  相似文献   
96.
Economic pressures and "value" judgments both compel and contaminate the current debate on the efficacy of psychotherapy. Too often, complex clinical trial outcome studies ignore the clinical or treatment process, as well as personality or contextual variables. Thus, they fail to build the foundations of a clinical science that makes possible the development of individually tailored treatment approaches and outcome predictions for specific patients with unique personalities, symptoms, and life circumstances. The real challenge, therefore, is for each psychotherapeutic approach to delineate its "process steps" and relate these steps to different outcomes. The "process" is the "final common pathway" for a number of patient, therapist, technique, and contextual variables. The capacity to predict the relationship between process and outcome at each stage in a therapeutic procedure is the relevant clinical test of "efficacy."  相似文献   
97.
beta-Ionone is found to stimulate considerably carotinoids synthesis in Blakeslea trispora. The stabilization of carotene-synthesizing ability of B. trispora in the presence of beta-ionine under prolonged incubation time is observed. Stabilization of polyribosomes in the presence of beta-ionine is observed when studying polyribosome content in B. trispora. A hypothesis is expressed on the existence of biochemical "receptors" as a linkage between synthesized protein and destroying mRNA.  相似文献   
98.
This paper explores the suitability of the emerging passive star-coupled optical interconnection using wavelength division multiplexing as the system interconnect to provide high bandwidth (Gbits/sec) communication demanded by heterogeneous systems. Several different communication strategies (combinations of communication topologies and protocols) are investigated under a representative master-slave computational model. The interplay between system speed, network speed, task granularity, and degree of parallelism is studied using both analytical modeling and simulations. It is shown that a hierarchical ALOHA-based communication strategy between the master and the slaves, implemented on top of the passive star-coupled network, leads to a considerable reduction in channel contention and provides 50–80% reduction in task completion time for applications with medium to high degrees of coarse grain parallelism. Comparable reduction in channel contention is also shown to be achieved by using tunable acoustooptic filters at master nodes.  相似文献   
99.
A number of wild plants, used by rural and tribal populations and contributing significantly to their livelihood and food security have escaped recognition and scientific inquiry. Their distribution, conservation, mode of harvest by locals and optimal use require region-specific assessment in order to integrate them into developmental interventions. This study analyzed the collection, consumption, sale and income from edible forest fruits in 49 tribal villages spread over five districts of Orissa State in eastern India. Density, dominance and diversity of species yielding wild fruit were measured by studying ecological parameters in the sample plots. We estimated an average of 48 fruit plants per hectare of deciduous forests. Fifty-six wild edible fruit species belonging to 40 genera in 26 families were recorded in the study region, many of which have multiple uses. Indigenous fruits formed part of the family diet with average annual consumption of 73 kg per household. Sale of wild fruits contributed 15 % of income for tribal households. Despite their good knowledge of indigenous fruits, the tribal populations have not adopted fruit tree farming which would enhance their nutrition and income.  相似文献   
100.
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