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   3587篇
  免费   320篇
  国内免费   264篇
电工技术   906篇
综合类   163篇
化学工业   594篇
金属工艺   356篇
机械仪表   191篇
建筑科学   163篇
矿业工程   43篇
能源动力   276篇
轻工业   301篇
水利工程   18篇
石油天然气   82篇
武器工业   24篇
无线电   257篇
一般工业技术   510篇
冶金工业   138篇
原子能技术   74篇
自动化技术   75篇
  2024年   10篇
  2023年   44篇
  2022年   66篇
  2021年   91篇
  2020年   77篇
  2019年   82篇
  2018年   91篇
  2017年   97篇
  2016年   107篇
  2015年   112篇
  2014年   207篇
  2013年   243篇
  2012年   280篇
  2011年   331篇
  2010年   225篇
  2009年   270篇
  2008年   214篇
  2007年   251篇
  2006年   226篇
  2005年   201篇
  2004年   147篇
  2003年   135篇
  2002年   102篇
  2001年   104篇
  2000年   92篇
  1999年   79篇
  1998年   52篇
  1997年   41篇
  1996年   42篇
  1995年   20篇
  1994年   35篇
  1993年   24篇
  1992年   15篇
  1991年   14篇
  1990年   8篇
  1989年   8篇
  1988年   6篇
  1987年   7篇
  1986年   4篇
  1985年   3篇
  1984年   5篇
  1980年   2篇
  1956年   1篇
排序方式: 共有4171条查询结果,搜索用时 15 毫秒
41.
利用废旧涂层硬质合金回收料生产硬质合金,通过采用适当的工艺方法,可以生产出质量较好的再生硬质合金产品。  相似文献   
42.
李中秋 《红水河》2011,(5):111-114
通过气象条件、地形以及线路结构参数等特点对将建的220 kV枣林Ⅱ回线路荆门段,可能导致线路导线舞动的原因进行了分析,并根据线路的自身特点和总结出的防舞经验,提出了该工程的导线防舞设计思路和措施,以便更好的应用到工程实例中进行检验.  相似文献   
43.
罗兰凤 《红水河》2011,(5):132-136
文章阐述了220 kV变电站的三相短路电流计算的重要性,并结合工程实例介绍了三相短路电流的计算过程及计算结果在变电站设计中的应用.  相似文献   
44.
Gold‐coated nanodisk arrays of nearly micron periodicity are reported that have high figure of merit (FOM) and sensitivity necessary for plasmonic refractometric sensing, with the added benefit of suitability for surface‐enhanced Raman scattering (SERS), large‐scale microfabrication using standard photolithographic techniques and a simple instrumental setup. Gold nanodisk arrays are covered with a gold layer to excite the Bragg modes (BM), which are the propagative surface plasmons localized by the diffraction from the disk array. This generates surface‐guided modes, localized as standing waves, leading to highly confined fields confirmed by a mapping of the SERS intensity and numerical simulations with 3D finite element method. The optimal gold‐coated nanodisk arrays are applied for refractometric sensing in transmission spectroscopy with better performance than nanohole arrays and they are integrated to a 96‐well plate reader for detection of IgY proteins in the nanometer range in PBS. The potential for sensing in biofluids is assessed with IgG detection in 1:1 diluted urine. The structure exhibits a high FOM of up to 46, exceeding the FOM of structures supporting surface plasmon polaritons and comparable to more complex nanostructures, demonstrating that subwavelength features are not necessary for high‐performance plasmonic sensing.  相似文献   
45.
In situ imaging and analysis of the mechanical behavior of micron‐sized metal‐coated polymer particles under compression is reported. A nanoindentation set‐up mounted in a scanning electron microscope is used to observe the deformation and fracture of 10 μm polymer spheres with Ni, Ni/Au, Au, and Ag coatings. The spheres fracture in one of two metallization‐dependent modes, brittle, and ductile, depending only on the presence of a nickel layer. The metal coating always fractures parallel to the direction of compression. The mechanical properties up to the point of coating fracture are rate‐dependent due to the viscoelastic polymer core. Metal‐coated polymer spheres are an important composite material in electronics packaging, and this study demonstrates a novel method of evaluating the mechanical properties of particles to tailor them for electronic materials.
  相似文献   
46.
简述了复合型导电高分子材料的研究及发展,并对其导电机理、基体树脂、导电填料的研究概况进行了述评,介绍了其在各领域中的应用.  相似文献   
47.
电晕放电是高压电力工程及航空航天领域研究的重点及难点问题;为研究尖端导体电晕放电的辐射特点,设计了电晕放电试验模拟系统;利用测试系统及天线在微波暗室内进行了不同测试距离、不同放电电压及不同尖端导体长度条件下的试验;通过对试验数据的分析可知,电晕放电辐射信号呈衰减振荡模式;电晕放电脉冲重复率随着充电电压的增大而增加;天线接收的辐射信号能量与测试距离成反比;随着充电电压的增加,信号辐射功率呈增加趋势;试验研究结果为输变电工程、航空航天装备的电磁环境分析提供参考。  相似文献   
48.
A biosensor based on bovine serum albumin (BSA) and poly-o-phenylenediamine (PoPD)/carbon-coated nickel (C-Ni) nanobiocomposite film modified electrode has been developed to study the interaction of BSA with papaverine (PAP). The well-dispersed C-Ni nanoparticles were dripped onto the glassy carbon electrode (GCE) surface firstly, and PoPD films were subsequently electropolymerized by cyclic voltammetry (CV) to prepare PoPD/C-Ni/GCE. Finally, the BSA was easily immobilized on the PoPD films via electrostatic adsorption. The morphology and the electrochemical properties of the fabricated composite electrodes were examined by scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS), respectively. The interaction of PAP with BSA was monitored by differential pulse voltammetry (DPV), using PoPD as the electrochemical indicator. The binding constant (K), obtained by DPV, was 1.7 × 104 L/mol, which was consistent with the fluorescence analysis. This constructed biosensor also exhibited a fine linear correlation with PAP concentration range of 2.5 × 10−9-4.5 × 10−5 mol/L and a detection limit of 8.3 × 10−10 mol/L was achieved by DPV.  相似文献   
49.
An approach is introduced for performing rigorous numerical simulations of electromagnetic wave scattering from randomly rough, perfectly conducting surfaces. It is based on a surface integral technique, and consists of determining the unknown electric surface current densities from which the electromagnetic field everywhere can be determined. The method is used to study the scattering of a p-polarized beam from an anisotropic Gaussian, randomly rough, perfectly conducting surface. It is demonstrated that the surface anisotropy gives rise to interesting and pronounced signatures in the angular intensity distribution of the scattered light. The origins of these features are discussed.  相似文献   
50.
Potentiometric cell, Au/LiCoO2 5 m/o Co3O4/Li2.88PO3.73N0.14/Li2CO3/Au, has been fabricated and investigated for monitoring CO2 gas. A LiCoO2–Co3O4 mixture was used as the solid-state reference electrode instead of a reference gas. The idea is to keep the lithium activity constant on the reference side using thermodynamic equilibrium at a given temperature. The thermodynamic stability of the reference electrode was studied from the phase stability diagram of Li–Co–C–O system. The Gibb’s free energy of formation of LiCoO2 was estimated at 500°C from the measured value of the cell emf. The sensors showed good reversibility and fast response toward changing CO2 concentrations from 200 to 3000 ppm. The emf values were found to follow a logarithmic Nernstian behavior in the 400–500°C temperature range. CH4 gas did not show any interference effect. Humidity and CO gas decreased the emf values of the sensor slightly. NO and NO2 gases affect this sensor significantly at low temperatures. However, increased operating temperature seems to reduce the 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