全文获取类型
收费全文 | 196篇 |
免费 | 9篇 |
专业分类
化学工业 | 27篇 |
金属工艺 | 23篇 |
机械仪表 | 8篇 |
建筑科学 | 6篇 |
能源动力 | 14篇 |
轻工业 | 24篇 |
石油天然气 | 3篇 |
无线电 | 33篇 |
一般工业技术 | 24篇 |
冶金工业 | 26篇 |
原子能技术 | 1篇 |
自动化技术 | 16篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 10篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有205条查询结果,搜索用时 15 毫秒
51.
In present work; epoxidized soybean oil (ESO), fly ash (FA) and natural clay (C) are used to produce 45 kinds of biocomposite
materials and by analyzing the physical–mechanical properties of these novel materials, their use as an insulation material
is investigated. The compressive strength, tensile strength, abrasion loss, thermal conductivity and oven-dry mass of each sample are measured.
The minimum thermal conductivity of 0.273 W/mK is observed with the samples containing ESO–FA–C. It is increased with the
decrease of ESO and FA. The compressive and tensile strengths are varied from 13.53 to 6.31 MPa and 1.287 to 0.879 MPa, respectively. 相似文献
52.
53.
54.
Railway and train security are very important in preventing service disruption and ensuring quality and safe journeys. Conventional gauges are used in laboratory environments for the strain measurement of rails used in railways. However, the use of these electrical sensors is not practical in long-distance railways. Instead, access to long distances is possible with fiber optic sensors. In this study, the strain of 49E1 type rail with R260 hardness and quality was calculated theoretically. These results were compared with an experimentally established fiber Bragg grating system. Moreover, a user-friendly interface was prepared for real-time monitoring of the system. Upon examining the results, the maximum deviation at a rate of 2.5% occurred in the strain measurement in the rail in response to force changes between 0 and 200 kN. A value of approximately 1.38?pm/µε was calculated between the wavelength/strain changes. 相似文献
55.
In Rhizopus oryzae cultivations, lactate production decreased and ethanol and biomass productions increased as inoculated spore concentration increased. Spore concentrations of 1 x 10(3) and 1 x 10(4) spores ml(-1) induced tightly packed clumps, whereas 1 x 10(5) and 1 x 10(6) spores ml(-1) induced filamentous growth. 相似文献
56.
In supply chain management process, the firm select best supplier takes the competitive advantage to other companies. Thus, supplier selection is an important issue and with the multiple criteria decision-making approach, the supplier selection problem includes both tangible and intangible factors. This paper is aimed to present an integrated fuzzy and linear programming approach to the problem. Firstly, linguistic values expressed in trapezoidal fuzzy numbers are applied to assess weights and ratings of supplier selection criteria. Then a hierarchy multiple model based on fuzzy set theory is expressed and fuzzy positive and negative ideal solutions are used to find each supplier’s closeness coefficient. Finally, a linear programming model based on the coefficients of suppliers, buyer’s budgeting, suppliers’ quality and capacity constraints is developed and order quantities assigned to each supplier according to the linear programming model. The integrated model is illustrated by an example in a textile firm. 相似文献
57.
58.
59.
A new analytical approach for obtaining the time samples of the retarded-time scalar and vector potentials due to an impulsively excited Rao-Wilton-Glisson (RWG) basis function is presented. The approach is formulated directly in the time-domain without any assumptions regarding the temporal behavior of the currents represented by the RWG bases. To the best knowledge of the authors, analytical evaluation of the potential integrals due to the RWG bases have not been formulated prior to the present work either in the time domain or the frequency domain. It is shown that the aforementioned potentials are related to the arc segments formed by the intersection of the triangular supports of the RWG basis and the sphere that is centered at the observation point and that has a radius R=ct, where c is the speed of light. In particular, the scalar potential is directly proportional to the total arc length and the vector potential is a function of the bisectors of these arc segments. A simple algorithm to evaluate these quantities is also presented. The validity of the obtained time-domain formulae is demonstrated through comparison of results to those obtained in the frequency domain by using numerical quadrature and transformed into time domain. 相似文献
60.
The noniterative method of adaptive channel equalization proposed by Butler and Cantoni [1] is investigated. Its start-up time is improved remarkably by choosing the period of the training sequence judiciously and performing the estimation of channel parameters exactly over one period. The resulting version of the algorithm is as fast as the fastest known iterative algorithms, such as Godard's Kaiman algorithm [2]. 相似文献