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   1536篇
  免费   60篇
  国内免费   1篇
电工技术   53篇
化学工业   307篇
金属工艺   33篇
机械仪表   29篇
建筑科学   34篇
矿业工程   6篇
能源动力   35篇
轻工业   101篇
水利工程   24篇
石油天然气   8篇
无线电   259篇
一般工业技术   205篇
冶金工业   262篇
原子能技术   12篇
自动化技术   229篇
  2023年   10篇
  2022年   9篇
  2021年   9篇
  2020年   13篇
  2019年   11篇
  2018年   12篇
  2017年   21篇
  2016年   21篇
  2015年   27篇
  2014年   33篇
  2013年   115篇
  2012年   25篇
  2011年   38篇
  2010年   50篇
  2009年   58篇
  2008年   40篇
  2007年   37篇
  2006年   61篇
  2005年   40篇
  2004年   42篇
  2003年   40篇
  2002年   44篇
  2001年   58篇
  2000年   45篇
  1999年   47篇
  1998年   38篇
  1997年   41篇
  1996年   53篇
  1995年   45篇
  1994年   42篇
  1993年   36篇
  1992年   19篇
  1991年   29篇
  1990年   40篇
  1989年   35篇
  1988年   44篇
  1987年   32篇
  1986年   17篇
  1985年   17篇
  1984年   16篇
  1983年   18篇
  1982年   14篇
  1981年   11篇
  1980年   12篇
  1979年   14篇
  1978年   13篇
  1977年   9篇
  1976年   18篇
  1975年   18篇
  1972年   8篇
排序方式: 共有1597条查询结果,搜索用时 0 毫秒
11.
Convergent and divergent validity are critically important in developing psychological measures that reveal interpretable deficits in disordered populations. This article reports on 2 studies that evaluated the validity of context processing measures. In Experiment 1, a confirmatory factor analysis of data from 481 healthy adults established the convergent validity of 2 context processing measures and showed that context processing accounted for significant amounts of variance in standard IQ and working memory measures. In Experiment 2, 20 schizophrenia patients, 16 of their healthy siblings, and 28 controls were evaluated using a novel, short context processing measure, the dot pattern expectancy (DPX) task. The DPX was sensitive to specific deficits in schizophrenia patients and their healthy siblings. These findings support the construct validity of context processing measures, suggest context processing is a component of intellectual functioning, and demonstrate that brief context processing measures remain sensitive to psychopathological deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
12.
Computers in police cruisers   总被引:1,自引:0,他引:1  
A typical police cruiser is filled with electronic devices, displays, and inputs, all competing for the officer's attention. The Project54 system integrates those devices, and its speech-based user interface lets officers operate them without taking their eyes off the road.  相似文献   
13.
This paper describes an adaptive bandwidth bus (ABB) architecture based on hybrid current/voltage mode repeaters for long global RC interconnect static busses that achieves high-data rates while minimizing the static power dissipation associated with current-mode signaling. Attaining a maximum aggregate bandwidth of 16 Gb/s (i.e., 1 Gb/s per line) across lossy on-chip interconnects spanning 1.75 cm in length, the bus core fabricated in 0.35 /spl mu/m CMOS technology dissipates approximately 93 mW with a supply of 2.5 V and signal activity of 0.5, equivalent to 5.71 pJ/bit. Experimental results using a 16-bit reference bus design that can be externally programmed to operate in voltage, current or adaptive modes indicate a 50% reduction in power dissipation over current-mode (CM) sensing, and an improvement in interconnection delay and signaling bandwidth of 35%-70% and 66% over voltage-mode (VM) sensing, respectively.  相似文献   
14.
Abstract

On the subject of fuzzy set-based approximate reasoning, this paper attempts to present a perspective that is both rigorously stated and different from the standard approach as stated by Mamdani and many others. Functionally speaking, this alternative perspective produces results essentially the same as the standard one, and in fact we intend to prove that subject to certain assumptions the results will be exactly die same. We feel however that the alternative perspective offers advantages in that it makes a more appropriate and more understandable use of such concepts as fuzzy relations, the extension principle, and fuzzy composition. If indeed it can lead to a clearer and more widespread understanding of the approximate reasoning formalism then this could conceivably spark broader interest in fuzzy control and other applications.  相似文献   
15.
16.
The response of metallic materials to shock loading, like all loading regimes, is controlled largely by factors operating at the microscopic or atomic levels. Over the past few years, face-centred cubic (fcc) metals have received a level of attention where the role of features such as stacking fault energy and precipitation hardening have been investigated. We now turn our attention to body-centred cubic (bcc) metals. In the past, only tantalum, tungsten, and their alloys have received significant attention at high strain-rate conditions due to their use by the ordnance community. In particular, this investigation examines the shear strength of these materials at shock loading conditions. Previous results on tantalum, tungsten, and a tungsten heavy alloy are reviewed, and more recent experiments on niobium, molybdenum, and Ta–2.5 wt% W presented. Results are discussed in terms of known deformation mechanisms and variations of Peierl’s stress.  相似文献   
17.
We describe a quasi-planar HBT process using a patterned implanted subcollector with a regrown MBE device layer. Using this process, we have demonstrated discrete SHBT with f/sub t/>250 GHz and DHBT with f/sub t/>230 GHz. The process eliminates the need to trade base resistance for extrinsic base/collector capacitance. Base/collector capacitance was reduced by a factor of 2 over the standard mesa device with a full overlap between the heavily doped base and subcollector regions. The low proportion of extrinsic base/collector capacitance enables further vertical scaling of the collector even in deep submicrometer emitters, thus allowing for higher current density operation. Demonstration ring oscillators fabricated with this process had excellent uniformity and yield with gate delay as low as 7 ps and power dissipation of 6 mW/CML gate. At lower bias current, the power delay product was as low as 20 fJ. To our knowledge, this is the first demonstration of high-performance HBTs and integrated circuits using a patterned implant on InP.  相似文献   
18.
A multiple-layer phantom consisting of a thin absorbing layer sandwiched between two nonabsorbing layers was created to simulate laser-induced thermal lesions in the eye. The nonabsorbing layers consisted of clear egg white, and the thin (20-40-μm) absorbing layer was created with black spray paint. Heat generated in the absorbing layer during 0.5-10-s argon irradiation was conducted to the adjacent egg white. Sufficient heat produced a region of coagulation that was graphically evidenced by the characteristic whiteness of cooked egg white. Light reflected from the lesion was monitored with a video camera and used as a feedback signal to control irradiation time. The laser irradiation was automatically ended when the diameter of the reflectance parameter related to coagulation thickness reached a preselected value  相似文献   
19.
This paper reports on state of-the-art HEMT devices and circuit results utilizing 32% and 60% indium content InGaAs channel metamorphic technology on GaAs substrates. The 60% In metamorphic HEMT (MHEMT) has achieved an excellent 0.61-dB minimum noise figure with 11.8 dB of associated gain at 26 GHz. Using this MHEMT technology, two and three-stage Ka-band low-noise amplifiers (LNAs) have demonstrated <1.4-dB noise figure with 16 dB of gain and <1.7 with 26 dB of gain, respectively. The 32% In MHEMT device has overcome the <3.5-V drain bias limitation of other MHEMT power devices, showing a power density of 650 mW/mm at 35 GHz, with Vds=6 V  相似文献   
20.
This paper considers the application of multiuser detection techniques to improve the quality of downlink reception in a multi-cell IS–95 digital cellular communication system. In order to understand the relative performance of suboptimum multiuser detectors including the matched filter detector, optimum multiuser detection in the context of the IS–95 downlink is first considered. A reduced complexity optimum detector that takes advantage of the structural properties of the IS–95 downlink and exhibits exponentially lower complexity than the brute-force optimum detector is developed. The Group Parallel Interference Cancellation (GPIC) detector, a suboptimum, low-complexity multiuser detector that also exploits the structure of the IS–95 downlink is then developed. Simulation evidence is presented that suggests that the performance of the GPIC detector may be near-optimum in several cases. The GPIC detector is also tested on a snapshot of on-air data measured with an omnidirectional antenna in an active IS–95 system and is shown to be effective for extracting weak downlink transmissions from strong out-of-cell cochannel interference. The results of this paper suggest that the GPIC detector offers the most performance gain in scenarios where weak downlink signals are corrupted by strong out-of-cell cochannel interference.  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