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   312篇
  免费   7篇
电工技术   34篇
化学工业   36篇
金属工艺   7篇
机械仪表   8篇
建筑科学   1篇
能源动力   5篇
轻工业   34篇
无线电   28篇
一般工业技术   59篇
冶金工业   88篇
原子能技术   3篇
自动化技术   16篇
  2023年   1篇
  2022年   4篇
  2021年   5篇
  2020年   3篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2016年   10篇
  2015年   5篇
  2014年   4篇
  2013年   14篇
  2012年   8篇
  2011年   13篇
  2010年   6篇
  2009年   5篇
  2008年   11篇
  2007年   9篇
  2006年   10篇
  2005年   10篇
  2004年   10篇
  2003年   12篇
  2002年   8篇
  2001年   6篇
  2000年   7篇
  1999年   10篇
  1998年   43篇
  1997年   22篇
  1996年   8篇
  1995年   6篇
  1994年   9篇
  1993年   6篇
  1992年   5篇
  1991年   4篇
  1990年   3篇
  1989年   1篇
  1988年   5篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1978年   2篇
  1976年   1篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
排序方式: 共有319条查询结果,搜索用时 15 毫秒
81.
Carbon-doped TiO2 thin films in the anatase phase with dopant concentrations of 1.1, 0.9, and 0.7 mol% were fabricated by a radio-frequency magnetron sputtering method. Dopant carbons were located at the oxygen sites. Carbon substitution caused the absorbance edge and/or the shoulder of TiO2 to shift to a higher wavelength region. Carbon-doped TiO2 thin films underwent a hydrophilic conversion when irradiating with visible light (400–530 nm). The hydrophilic property under visible light was inferior to that under ultraviolet light, which is explained by considering that the visible light sensitivity originates from the localized C 2p formed in the band-gap.  相似文献   
82.
To investigate the usefulness of a periodic medical checkup at the workplace from the standpoint of remembering the results, a survey was performed by a self-rating questionnaire on 424 industrial workers in a certain manufacturing company. The questionnaire included several items, such as their recalled abnormal medical findings and follow-up toward them, Breslow's 7 health practices, Goldberg's 12 selected items from the Japanese version of the General Health Questionnaire, and other original health related items. The study was conducted a month after the workers received their results. A total of 391 (290 males and 101 females) or 92.2% responded to the questionnaire. Several factors, such as age, gender, the type of occupation, and perceived health status were significantly correlated to the recalled results of medical checkups, but, only age and the way of observing the results were in accordance with the actual results. Only forty-nine percent of the responders correctly remembered their results. Age and perceived health status were significantly correlated to the exact recollection of the results. In particular, those who had poor perceived health status tended to have a wrong understanding of their medical results. Furthermore, there were those with the highest averaged GHQ scores who responded as having some abnormal findings even though no abnormalities were discovered in the medical checkups. On the other hand, there were those with the lowest averaged GHQ scores who answered that they had no abnormal findings even though some abnormalities were revealed in the medical checkups. The frequency of correct follow-up of the results was lower than the exact recalling of the results. In addition, those who made a mistake in the follow-up were inclined to have an optimistic view. Therefore, comprehensive health care for precise recalling of the results of medical checkups should be required to improve abnormal findings or maintain a good health status.  相似文献   
83.
Co and Mn ferrites were prepared by air oxidation of their hydroxide precursors in suspensions. The distributions of Co or Mn within the particles were evaluated by dissolving the particles in a HCl solution, and determining the amount of Co or Mn released from the particles at different times. The evaluation revealed that a considerably high Mn concentration was found near the surface of the Mn ferrite particles, and that the Co concentration was uniform throughout the Co ferrite particles.  相似文献   
84.
Thermoelectric properties of heterogeneous materials are discussed in terms of a randomly oriented rectangular plate-like mosaic of anisotropic crystalline grains embedded in a homogeneous host material. Anisotropies in effective thermoelectric parameters and the values of thermoelectric parameters can be related to the mean orientation of the plate-like grains which, in turn, can be related to the orientation factor of Lotgering. They are also functions of various parameters such as dimension ratios , and of electrical resistivities, thermal conductivities, and the Seebeck coefficient, respectively, of grains to those of host medium. Use of f-dependent anisotropies in conjunction with relative magnitudes of electrical and thermal conductivities as well as of the Seebeck coefficient, allows , and to be estimated, which characterize the intergranular medium.  相似文献   
85.
86.
This paper presents a practical prototype of a multi‐primary image projector system in which light source spectra can be programmable for suiting any purpose. Our multi‐primary projection system is mainly configured with a light source component and an image projection component. The programmable light source can reproduce any spectral curve. Spatial images are then generated using a digital mirror device chip that quickly controls the intensity of the light source spectra in 2D image plane. The multi‐primary images in our projection system are reproduced by multiplexing the time‐sequential images with different primary colors. Our multi‐primary image projector realizes not only wide gamut projection but also spectral projection. To achieve this, we also show how light source spectra of four or six primary colors are designed.  相似文献   
87.
We investigate the nucleation behavior in the electroless displacement deposition of metal particles (Pt, Rh, Pd, Cu, Ag, and Au) onto n-Si wafers from a metal-salt solution containing HF. The particle density of metals varies widely from 106 (Pt) to 1011 (Au) cm−2, depending on the kind of metal. Deposited metals can be classified into two types of nucleation behavior. One consists of the platinum group elements, including Pt, Rh, and Pd, which display lower particle densities than elements of the other group and depend on the type of pretreatment of the n-Si wafer, and thus the surface conditions of Si. The second group consists of the copper group elements, including Cu, Ag, and Au, which display higher particle density than the first group and are independent of pretreatment. The size of deposited particles decreases from hundreds nm to tens nm as the particle density increases. Moreover, the displacement deposition of the Pt and Ag particles onto n-Si are in progressive and instantaneous nucleation modes, respectively.  相似文献   
88.
Hierarchical power distribution with a power tree has been developed. The key features are a power-tree structure with three power-tree management rules and a distributed common power domain implementation. The hierarchical power distribution supports a fine-grained power gating with dozens of power domains, which is analogous to a fine-grained clock gating. Leakage currents of a 1 000 000-gate power domain were effectively reduced to 1/4000 in multi-CPU SoCs with minimal area overhead  相似文献   
89.
Stochastic volatility processes are used in multi-variate time series analysis to track time-varying patterns in covariance matrices. Uhlig extended (UE) and beta-Bartlett (BB) processes are especially convenient for analyzing high-dimensional time series because they are conjugate with Wishart likelihoods. In this article, we show that UE and BB are closely related, but not equivalent: their hyperparameters can be matched so that they have the same forward-filtered posteriors and one-step ahead forecasts, but different joint (smoothed) posterior distributions. Under this circumstance, Bayes factors cannot discriminate the models and alternative approaches to model comparison are needed. We illustrate these issues in a retrospective analysis of volatilities of returns of foreign exchange rates. Additionally, we provide a backward sampling algorithm for the BB process, for which retrospective analysis had not been developed.  相似文献   
90.
This paper describes new test methods and some typical test results for a recently developed external insulation in Japan. The paper starts with the introduction of the results of the tests that were conducted specially on the external insulation for 1100 kV/10 GW ac transmission line and ±500 kV/2.8 GW dc overhead line section, recently constructed in Japan using heavy duty insulators and giant bushings. Various special tests were made on the external insulation in order to investigate the performance at such high service voltages since those had never been used before, and secondly because of the high reliability required and the importance of the lines. Introduces test methods and some related results on long term performance for the new type of insulators, such as semiconducting glaze and polymer insulators. Also included in the paper are the development of some special test methods and results on line arresters for transmission and distribution lines, which have been accepted widely in Japan  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