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   101篇
  免费   10篇
  国内免费   7篇
电工技术   14篇
综合类   1篇
化学工业   32篇
金属工艺   1篇
机械仪表   3篇
建筑科学   2篇
能源动力   1篇
轻工业   15篇
一般工业技术   23篇
冶金工业   2篇
原子能技术   7篇
自动化技术   17篇
  2021年   1篇
  2020年   1篇
  2018年   4篇
  2017年   7篇
  2016年   5篇
  2014年   1篇
  2013年   29篇
  2012年   1篇
  2011年   2篇
  2010年   4篇
  2009年   1篇
  2008年   3篇
  2007年   1篇
  2006年   3篇
  2004年   1篇
  2003年   2篇
  2002年   2篇
  1998年   2篇
  1997年   8篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1992年   2篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   4篇
  1986年   1篇
  1985年   5篇
  1983年   3篇
  1982年   3篇
  1980年   2篇
  1979年   2篇
  1977年   4篇
  1976年   3篇
  1972年   1篇
  1960年   1篇
排序方式: 共有118条查询结果,搜索用时 15 毫秒
1.
The mechanism of colour change during the pigment dispersion process and during powder application to the skin surface was studied by examining the colour extension properties of Yellow. Red , and Black iron oxides in white powder bases. A new measure for the evaluation of the degree of colour extension was devised. This measure corresponded well with human visual sensation, and was found to be useful for comparing the rates of colour extension of pigments. The rate of colour extension of pigments was found to vary in the order: Yellow acicular Red granular Red Black. This result explains colour darkening and the change towards reddish tones during the pigment dispersion process, because Yellow extends fully in the early stage of the process but Red , especially in granular form, and Black continue to extend even in the later stage. Acicular Red iron oxide is more favourably employed than the granular form to attain sufficient colour extension of foundations with lower energy expenditure, and to decrease the discrepancy between the cake colour and the colour of applied powder.
Le développement des oxydes de fer et effet sur les nuances des fonds de teint compacts  相似文献   
2.
A thermo gravimetric study of the oxidation behavior of chemically vapor-deposited amorphous and crystalline Si3N4 (CVD Si3N4) was made in dry oxygen (0.1 MPa) at 1550° to 1650°C. The specimens were prepared under various deposition conditions using a mixture of SiCl4, NH3, and H2 gases. The crystalline CVD Si3N4 indicated a parabolic oxidation kinetics over the whole temperature range, whereas the amorphous CVD Si3N4 changed from a parabolic to a linear law with increased temperature. The oxidation mechanism is discussed in terms of the activation energy for the oxidation and the microstructure of the formed oxide films.  相似文献   
3.
1 IntroductionTheelectricaltransportproperties (conductiontype ,carrierconcentration ,carriermobility ,carriereffectivemass)andthethermaltransportproperties (atomdis placementparameter ,meanfreepathofphonon ,latticethermalconductivity)offilledskutteruditecomp…  相似文献   
4.
The oxidation behavior of Hastelloy-XR alloy was investigated to obtain the optimum surface condition for corrosion-resistant glass-coatings. The surface morphology of oxide scales changed significantly with variation of temperatureand oxygen partial pressure (po2 ). The oxidation kinetics was mainly parabolic independent of oxidation conditions.The oxide scales were consisted of inner Cr2O3 and outer spinel layers. The phase component of spinel layers wereMn1.5Cr1.5O4 and (Mn,Ni)(Cr,Fe)2O4 for the oxygen partial pressures po2<10 kPa and po2>10 kPa, respectively.The optimum oxidation condition to obtain an oxide scale for well-adhered glass-coating to the substrate was 1248 Kand po2 =0.01 kPa for the oxidation time of 43 ks.  相似文献   
5.
High penetration of renewable generation systems will lead to supply–demand imbalances, and will also require output curtailment of renewable power plants. We focused on management of electric vehicle fleet charging which can promote charging during specific time zone for reducing this curtailment. In this study, we evaluated the Charging Promoting Potential (CPP) of passenger electric vehicles (EVs) using optimization model based on the mixed‐integer linear programming. In addition, we also evaluated the CPP of other EVs, such as electric buses and electric trucks. We found that wider zone of the charging promoting time led effective concentration of charging load. Furthermore, we found that the CPP of the electric buses is higher than those of the passenger EVs and electric trucks.  相似文献   
6.
Dry‐cured and extruded three‐layer (E‐E type) 6.6‐kV cross‐linked polyethylene (XLPE) cables were introduced into electric power systems more than 30 years ago, but they do not experience failures because of water tree degradation. Also, the degradation index of water treeing for these cables has not been established. Therefore, investigating results of residual breakdown voltage and water tree degradation of these cables will help us plan for cable replacement and determine water tree degradation diagnosis scheduling, and will be fundamental data for cable lifetime evaluation. In this study, the authors measured the ac breakdown voltages of dry‐cured and E‐E type 6.6‐kV XLPE cables removed after 18 to 25 years of operation and observed the water trees in their XLPE insulation. As a result, it was observed that breakdown voltages were larger than the maximum operating voltage (6.9 kV) and the ac voltage for the dielectric withstanding test (10.3 kV). Water trees were mainly bow‐tie water trees and their maximum length was approximately 1 mm. Although the number of measured cables was limited, the lifetime of this type of cable was estimated to be approximately 40 years, even experiencing water immersion.  相似文献   
7.
Fractional‐slot windings are widely used in rotating machines in order to improve the output voltage waveform, increase the design flexibility, and gain many other advantages. However, fractional‐slot windings are known to produce different harmonic components such as an even order and/or fractional number of space flux harmonics compared to integral‐slot windings. These harmonics may increase stray losses and cause stator core vibration. This paper describes an analysis of space flux harmonics and proposes new winding methods such as “novel interspersed windings” to reduce these harmonic components. The proposed winding methods were verified by numerical analysis and model tests.  相似文献   
8.
This paper deals with the optimum design of linear multivariate sampled-data control systems,

Section 2 is concerned with the design of such control systems which are optimum on the basis of deadbeat performance. This design procedure is general and can be applied similarly to any deterministic inputs such as step, ramp, etc.

Section 3 is concerned with such control systems with respect to an integral form performance criterion. It is desired that the performance index takes the form of an integral, especially when the state variables of a control system are continuous with respect to time. For this reason, the minimum integral control is considered here.

The performance limits for such systems optimized for a deterministic input are considered in §4, and some interesting theorems are proved by using the w-transform.  相似文献   
9.
This paper is concerned with the problem of identifying parameters in stochastic systems described by single-input single-output linear discrete-time equations. A stable estimation error system is developed by using the extended Kalman filter technique and the concept of strictly positive real transfer function. The identifier corresponding to the estimation error system is constructed, and the convergence of parameter estimates to the exact values is proved under some bounded conditions. It is shown that the recursive maximum likelihood identifier and the recursive extended least squares identifier are obtained by neglecting the correction terms in the proposed identifier. Numerical examples for a fourth-order system are presented to illustrate the effectiveness of the proposed method.  相似文献   
10.
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