全文获取类型
收费全文 | 1552篇 |
免费 | 86篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 19篇 |
综合类 | 1篇 |
化学工业 | 360篇 |
金属工艺 | 84篇 |
机械仪表 | 43篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 52篇 |
轻工业 | 63篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 226篇 |
一般工业技术 | 358篇 |
冶金工业 | 255篇 |
原子能技术 | 11篇 |
自动化技术 | 152篇 |
出版年
2023年 | 13篇 |
2022年 | 30篇 |
2021年 | 42篇 |
2020年 | 43篇 |
2019年 | 51篇 |
2018年 | 65篇 |
2017年 | 68篇 |
2016年 | 49篇 |
2015年 | 38篇 |
2014年 | 59篇 |
2013年 | 99篇 |
2012年 | 64篇 |
2011年 | 92篇 |
2010年 | 56篇 |
2009年 | 69篇 |
2008年 | 60篇 |
2007年 | 46篇 |
2006年 | 42篇 |
2005年 | 30篇 |
2004年 | 42篇 |
2003年 | 19篇 |
2002年 | 23篇 |
2001年 | 23篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 43篇 |
1997年 | 27篇 |
1996年 | 31篇 |
1995年 | 24篇 |
1994年 | 23篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 34篇 |
1990年 | 14篇 |
1989年 | 21篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 27篇 |
1985年 | 20篇 |
1984年 | 18篇 |
1983年 | 18篇 |
1982年 | 27篇 |
1981年 | 31篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1972年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有1661条查询结果,搜索用时 843 毫秒
81.
82.
83.
84.
Joseph Sam Armijo Piyush Kar Manoranjan Misra 《Nuclear Engineering and Design》2006,236(24):2589-2598
The reference waste package design and operating mode to be used in the Yucca Mountain Repository is reviewed. An alternate (second generation) operating concept and waste package design is proposed to reduce the risk of localized corrosion of waste packages and to reduce repository costs. The second generation waste package design and storage concept is proposed for implementation after the initial licensing and operation of the reference repository design. Implementation of the second generation concept at Yucca Mountain would follow regulatory processes analogous to those used successfully to extend the design life and uprate the power of commercial light water nuclear reactors in the United States. The second generation concept utilizes the benefits of hot dry storage to minimize the potential for localized corrosion of the waste package by liquid electrolytes. The second generation concept permits major reductions in repository costs by increasing the number of fuel assemblies stored in each waste package, by eliminating the need for titanium drip shields and by fabricating the outer container from corrosion resistant low alloy carbon steel. 相似文献
85.
Jignasu P. Mehta Prashant N. Bhatt Sudhindra N. Misra 《中国稀土学报(英文版)》2006,24(6):648-652
Pr( Ⅲ ) and Nd( Ⅲ ) can be utilized as absorption spectroscopic probes to investigate the interaction of biomolecules like Lysozyme (HEW) with Ca( Ⅱ ) in-vitro ; the most abundant metal ion in the human body system. The spectroscopic techniques involving comparative absorption, absorption difference, and quantitative intensity analysis using 4f-4f transitions are utilized for changes in the inner sphere coordination pattern of Pr( Ⅲ ) and Nd(Ⅲ ) in solution as well as in solid state. The present study deals with an important biomolecule in human metabolism, that is, Lysozyme (HEW). The absorption er-Condon the probab spectral parameters such as the oscillator strength (P), the Judd-Ofelt (Tλ) intensity parameters, and the Slatinter electronic parameters are calculated using chi square methods. The obtained results are used to determine le geometry of the complex in the solution, the nature of the bond between Pr(Ⅲ)/Nd(Ⅲ) with lysozyme, and the inner sphere coordination environment of f-f transitions. The results obtained from various experimental conditions are utilized to investigate the coordination changes in the Pr(Ⅲ)/Nd(Ⅲ) complexes caused by different coordinating sites of lysozyme, normalized bite, denticity, the solvent nature, the coordination number, the nature of bond and other parameters to mimic the interaction of the Ca( Ⅱ ) ion with such biomolecule. 相似文献
86.
Chandan Singh Author Vitae 《Pattern recognition》2006,39(11):2047-2064
Zernike moments which are superior to geometric moments because of their special properties of image reconstruction and immunity to noise, suffer from several discretization errors. These errors lead to poor quality of reconstructed image and wide variations in the numerical values of the moments. The predominant factor, as observed in this paper, is due to the discrete integer implementation of the steps involved in moment calculation. It is shown in this paper that by modifying the algorithms to include discrete float implementation, the quality of the reconstructed image improves significantly and the first-order moment becomes zero. Low-order Zernike moments have been found to be stable under linear transformations while the high-order moments have large variations. The large variations in high-order moments, however, do not greatly affect the quality of the reconstructed image, implying that they should be ignored when numerical values of moments are used as features. The 11 functions based on geometric moments have also been found to be stable under linear transformations and thus these can be used as features. Pixel level analysis of the images has been carried out to strengthen the results. 相似文献
87.
Prawal Sinha Chandan Singh K.R. Prasad 《International Journal of Engineering Science》1982,20(9):1037-1048
The hydrodynamics of the self propulsion of a spermatozoa, swimming through the mucus filling the cervical channel, is investigated. The mucus is modeled as a micropolar fluid and the spermatozoa as a 2-dimensional sheet swimming at low Reynolds number between two rigid walls. The wavelengths of the propulsive waves passing down the sheet are assumed to be very large compared to the channel spacing, but the amplitude of the propulsive waves is arbitrary. Expressions for the propulsive velocity and the energy expended by the swimming sheet are obtained in terms of various parameters involved. The results are elaborated through graphs. It is found that both the propulsive velocity and the rate of working by the sheet increase as the value of the micropolar parameters increases and that of decreases. 相似文献
88.
For large well-connected reliability networks, it has been observed that the delta and star transformations are sometimes unable to tackle the complexity of the network. The quadrilateral-star transformation may be helpful in initiating network reduction under these circumstances. Probability conditions for approximate equivalence of quadrilateral and star networks have been derived. Using these conditions, six different sets of transformation equations have been obtained and compared from the point of view of accuracy. 相似文献
89.
The Landsat multispectral scanner data have been analyzed with a view toward crop identification and inventory. The notion of spectral-temporal trajectory as crop signature, introduced in an earlier paper, has been further developed leading to a formulation of the problem similar to one of recognition of hand-written characters. A simple classification rule based on angular features of the trajectory is discussed and classification results are given for Landsat images from several sites. 相似文献
90.
Mathematical statistics are used to design electronic systems in which the effects of the initial variations of the system parameters and the drift of these parameters on the system performance criteria are a minimum. This is accomplished by minimizing the initial variances of the system performance criteria with respect to the initial mean values of the system parameters while constraining the means of these parameters to their required values. In addition, the drift rates of the system parameters are selected in such a manner as to prevent the drift of the mean values of the system performance criteria while reducing the tendencies of the variances of these criteria to increase with time. These techniques were successfully applied to a number of electronic systems, including systems with both active and passive elements, thus illustrating the usefulness of mathematical statistics in the design of mass produced electronic systems. 相似文献