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   713篇
  免费   42篇
  国内免费   7篇
电工技术   9篇
化学工业   176篇
金属工艺   7篇
机械仪表   11篇
建筑科学   13篇
矿业工程   5篇
能源动力   46篇
轻工业   74篇
水利工程   5篇
石油天然气   5篇
无线电   80篇
一般工业技术   198篇
冶金工业   55篇
原子能技术   3篇
自动化技术   75篇
  2024年   2篇
  2023年   20篇
  2022年   39篇
  2021年   55篇
  2020年   40篇
  2019年   39篇
  2018年   63篇
  2017年   40篇
  2016年   45篇
  2015年   16篇
  2014年   30篇
  2013年   39篇
  2012年   32篇
  2011年   48篇
  2010年   28篇
  2009年   26篇
  2008年   35篇
  2007年   19篇
  2006年   9篇
  2005年   8篇
  2004年   9篇
  2003年   7篇
  2002年   9篇
  2001年   4篇
  2000年   2篇
  1999年   7篇
  1998年   7篇
  1997年   6篇
  1996年   5篇
  1995年   10篇
  1994年   6篇
  1993年   8篇
  1992年   5篇
  1991年   2篇
  1990年   4篇
  1989年   9篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1985年   3篇
  1984年   6篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1976年   2篇
  1975年   2篇
排序方式: 共有762条查询结果,搜索用时 191 毫秒
1.

The scintillator detectors are recalibrated against the datasheet given by the manufacturer. Optimal and mutual dependent values of (a) high voltage at PMT (Photomultiplier Tube), (b) amplifier gain, (c) average time to count the radiation particles (set by operator), and (d) number of instances/sample number are estimated. Total 5: two versions of Central Limit Theorem (CLT), (3) industry preferred Pulse Width Saturation, (4) calibration based on MPPC coupled Gamma-ray detector, and (5) gross method are used. It is shown that the CLT method is the most optimal method to calibrate the detector and its respective electronics couple. An inverse modeling-based Computerized Tomography method is used for verification. It is shown that statistically averaging results are more accurate and precise data than mode and median if the data is not skewed and a random number of samples are used during the calibration process. It is also shown that the average time to count the radiation particle is the most important parameter affecting the optimal calibration setting for precision and accurate measurements of gamma radiation.

  相似文献   
2.
3.
4.
Wireless Personal Communications - Major issue in marine environment imaging is the expulsion of hazy scenes caused by natural phenomena such as absorption and scattering in underwater images. The...  相似文献   
5.
6.
7.
The present study reports the preparation and application of a novel biopolymer-based composite hydrogel (BCH) for removal of synthetic dye rhodamine 6G (Rh6G). BCH was prepared from biopolymer chitosan and acrylic acid monomer, in the presence of initiator (K2S2O8) and cross-linker thiourea using microwave irradiation. Synthesized chitosan-based composite hydrogel was characterized by using analytical techniques including Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), derivative thermogravimetric analysis (DTA) and differential thermal analysis (DTG). The stability of the adsorbent was demonstrated from its water uptake capacity. The dynamics of water sorption study showed the Fickian behavior. The investigations were continued to assess the adsorption potential of BCH for removal of Rh6G from aqueous solution. The effect of process parameters affecting the adsorption of rhodamine 6G (Rh6G), such as adsorbent dose, initial concentration of pollutant, contact time and pH of the solution was evaluated. Removal efficiency of chitosan-based composite hydrogel (BCH) was found to be 87.31% at pH 7 for BCH dose of 1 g/L after 8 h. The obtained data were fitted to adsorption isotherms and kinetics models. The adsorption equilibrium isotherm and kinetics studies indicated that the pseudo-second-order model and the Freundlich model well described the adsorption equilibrium of Rh6G on BCH.  相似文献   
8.
The effect of single-layer pyrocarbon (PyC) and multilayered (PyC/SiC)n=4 interphases on the flexural strength of un-coated and SiC seal-coated stitched 2D carbon fiber reinforced silicon carbide (Cf/SiC) composites was investigated. The composites were prepared by I-CVI process. Flexural strength of the composites was measured at 1200 °C in air atmosphere. It was observed that irrespective of the type of interphase, the seal coated samples showed a higher value of flexural strength as compared to the uncoated samples. The flexural strength of 470 ± 12 MPa was observed for the seal coated Cf/SiC composite samples with multilayered interphase. The seal coated samples with single layer PyC interphase showed flexural strength of 370 ± 20 MPa. The fractured surfaces of tested samples were analyzed in detail to study the fracture phenomena. Based on microstructure-property relations, a mechanism has been proposed for the increase of flexural properties of Cf/SiC composites having multilayered interphase.  相似文献   
9.
The present study attempts quantitative determination of changes in the morphological surface features viz. fractal dimension, lower and upper cut off length scale through Power Spectral Density analysis prior to and after irradiation of 100 KeV Ar+ ion beam at incidence angles of 0°, 40° and 60° on ZnO thin films. All the unirradiated and irradiated samples are subjected to photoelectrochemical characterization and a correlation between photoelectrochemical performance and morphological parameters is established. Sample irradiated at 40° angle at the fluence of 5 × 1016 ions/cm2 is found to possess maximum fractal dimension of 2.72, lower and upper cut off length scale of 3.16 nm and 63.00 nm respectively. This sample exhibits maximum photocurrent density of 3.19 mA/cm2 and applied bias photon-to-current efficiency of 1.12% at 1.23 V/RHE. Hydrogen gas collected for duration of 1 h for the same sample was ~4.83 mLcm?2.  相似文献   
10.
Journal of Applied Electrochemistry - The inhibitive action of 2-aminobenzothiazole (ABT) on the corrosion of AA6061-T6 was evaluated in 0.5 M HCl by electrochemical techniques. The...  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