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   101229篇
  免费   1768篇
  国内免费   539篇
电工技术   1074篇
综合类   2347篇
化学工业   15415篇
金属工艺   5294篇
机械仪表   3607篇
建筑科学   2518篇
矿业工程   598篇
能源动力   2454篇
轻工业   4718篇
水利工程   1387篇
石油天然气   425篇
武器工业   1篇
无线电   11370篇
一般工业技术   20158篇
冶金工业   3951篇
原子能技术   418篇
自动化技术   27801篇
  2024年   101篇
  2023年   421篇
  2022年   998篇
  2021年   1166篇
  2020年   911篇
  2019年   946篇
  2018年   15264篇
  2017年   14030篇
  2016年   10693篇
  2015年   1187篇
  2014年   1056篇
  2013年   1694篇
  2012年   3984篇
  2011年   10310篇
  2010年   8999篇
  2009年   6283篇
  2008年   7403篇
  2007年   8260篇
  2006年   590篇
  2005年   1557篇
  2004年   1379篇
  2003年   1389篇
  2002年   723篇
  2001年   273篇
  2000年   349篇
  1999年   233篇
  1998年   347篇
  1997年   269篇
  1996年   265篇
  1995年   180篇
  1994年   174篇
  1993年   160篇
  1992年   115篇
  1991年   155篇
  1990年   101篇
  1989年   95篇
  1988年   90篇
  1987年   90篇
  1986年   76篇
  1985年   87篇
  1984年   74篇
  1983年   73篇
  1982年   63篇
  1981年   72篇
  1980年   50篇
  1968年   46篇
  1966年   43篇
  1965年   46篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Microsystem Technologies - The quantitative analysis of microwave noise available in the double gate (DG) high electron transistors of mobility (HEMT) is reported in this paper. For this analysis,...  相似文献   
52.
Preface     
Microsystem Technologies -  相似文献   
53.
Many video service sites headed by YouTube know what content requires copyright protection. However, they lack a copyright protection system that automatically distinguishes whether uploaded videos contain legal or illegal content. Existing protection techniques use content-based retrieval methods that compare the features of video. However, if the video encoding has changed in resolution, bit-rate or codec, these techniques do not perform well. Thus, this paper proposes a novel video matching algorithm even if the type of encoding has changed. We also suggest an intelligent copyright protection system using the proposed algorithm. This can serve to automatically prevent the uploading of illegal content. The proposed method has represented the accuracy of 97% with searching algorithm in video-matching experiments and 98.62% with automation algorithm in copyright-protection experiments. Therefore, this system could form a core technology that identifies illegal content and automatically excludes access to illegal content by many video service sites.  相似文献   
54.
In this paper we have proposed a dynamic pricing scheme for the contributing peers in the Video on Demand (VoD) system. The scheme provides an effective mechanism to maximize the profit through the residual resources of the contributing peers. A utilization function is executed for each contributing peer to estimate the utility factor based on the parameters such as initial setup cost, holding cost, chaining cost and salvage cost. In this paper, we urge an effective dynamic pricing algorithm that efficiently utilizes a range of parameters with a varying degree of complexity. The key findings of the algorithm are (i) each contributing peers are benefitted by the monetary based on its resource contributions to the VoD system and (ii) a high degree of social optimum is established by proficiently aggregating the contributing peer’s resources with the overall resources of the VoD system. We validate our claim by simulating the proposed dynamic pricing scheme with other standard pricing schemes such as altruism, cost model and game theory perspective. The result of our dynamic pricing scheme shows the best utility factor than other standard pricing schemes.  相似文献   
55.
The neutron spectra transmitted across a fission-suppressed hybrid blanket and its components, driven by a low intensity 14 MeV Haefely neutron generator, were measured with a 2×2 NE213 detector at LOTUS facility. These experiments have been analyzed with 2D and 3D codes DOT3.5 and MCNP, respectively. The spectral integrals between 15 to 1 MeV show good agreement among the 2D, the 3D, and the NE213 for 15 cm lead, 18 cm beryllium, and 25 cm graphite slabs. However, there are large discrepancies for 6.2 cm stainless steel and 15 cm lithium carbonate slabs. The assemblies involving two or more of these slabs reflect these tendencies. We observe also considerable disagreement over pointwise spectra for a number of assemblies.Work done while on visiting assignment to Institut de Génie Atomique, E.P.F.L.  相似文献   
56.
Silicon - The primary purpose of this work is to study the effect of symmetric and asymmetric variation of underlap regions both on source and drain side of 3D SOI n-FinFET. Underlap length is...  相似文献   
57.
Reddy  N. Nagendra  Panda  Deepak Kumar 《SILICON》2021,13(12):4545-4551
Silicon - In this paper, a dielectric modulated dual material gate TFET (DM-DMG_TFET)based biosensor is proposed. In order to detect various biomolecules, a nanogap cavity is formed by the...  相似文献   
58.

The quantum-dot cellular automata (QCA) is considered to be one of the ground-breaking nanotechnologies developed over the last two decades. A layered T (LT) logic cell library is constructed herein, and the methodology is extended to generic adder and subtractor module designs. The two proposed algorithms lead to more efficient QCA layout designs for an n-bit ripple carry adder (RCA) and subtractor based on an effective clock zone assignment approach. The suggested one-, four-, and eight-bit RCAs and subtractors surpass most of their existing counterparts by offering lower effective area and cell complexity. A comparative analysis is presented regarding the complexity, irreversible power dissipation, and Costα of the proposed n-bit layouts from a cost estimation purview.

  相似文献   
59.
Distortion as a result of the quenching process is predominantly due to the thermal gradient and phase transformations within the component. Compared with traditional liquid quenching, the thermal boundary conditions during gas quenching are relatively simple to control. By adjusting the gas-quenching furnace pressure, the flow speed, or the spray nozzle configuration, the heat-transfer coefficients can be designed in terms of both the component geometry and the quenching time. The purpose of this research is to apply the optimization methodology to design the gas-quenching process. The design objective is to minimize the distortion caused by quenching. Constraints on the average surface hardness, and its distribution and residual stress are imposed. The heat-transfer coefficients are used as design variables. DEFORM-HT is used to predict material response during quenching. The response surface method is used to obtain the analytical models of the objective function and constraints in terms of the design variables. Once the response surfaces of the objective and constraints are obtained, they are used to search for the optimum heat-transfer coefficients. This process is then used instead of the finite-element analysis. A one-gear blank case study is used to demonstrate the optimization scheme.  相似文献   
60.
Organofunctional silanes recently have emerged as outstanding, environmentally friendly corrosion protectors for metal substrates, compared with conventional chromate treatments. A simple immersion technique is typically used to coat the metal surface with silane films. However, the thickness and uniformity of the films are uncontrolled in this process. This paper proposes a new deposition technique for the silane films on the metal surface, i.e., by electrodeposition. Hydrolyzed silanes are water-soluble, ionized molecules, so they can be deposited on metals by electrodeposition. Various combinations of silane mixtures were tested at different voltages, pH values, bath concentrations, and exposure times on panels of alloy aluminum and mirror-polished ferro-plate. The surface structure was characterized by scanning electron microscopy (SEM) and ellipsometry. The resistance of the film to corrosion was investigated by direct current (DC) polarization and electrochemical impedance spectroscopy (EIS) techniques. Electrodeposition results in a more organized and uniform film with fewer pores, compared with immersed or dipped films. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appears on pp. 320–26 of the Proceedings.  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