全文获取类型
收费全文 | 36900篇 |
免费 | 4073篇 |
国内免费 | 2084篇 |
专业分类
电工技术 | 2886篇 |
技术理论 | 3篇 |
综合类 | 4718篇 |
化学工业 | 1915篇 |
金属工艺 | 719篇 |
机械仪表 | 1771篇 |
建筑科学 | 4491篇 |
矿业工程 | 1870篇 |
能源动力 | 1027篇 |
轻工业 | 4077篇 |
水利工程 | 2064篇 |
石油天然气 | 4175篇 |
武器工业 | 851篇 |
无线电 | 2392篇 |
一般工业技术 | 2401篇 |
冶金工业 | 1111篇 |
原子能技术 | 272篇 |
自动化技术 | 6314篇 |
出版年
2024年 | 228篇 |
2023年 | 582篇 |
2022年 | 1090篇 |
2021年 | 1308篇 |
2020年 | 1414篇 |
2019年 | 1137篇 |
2018年 | 1130篇 |
2017年 | 1196篇 |
2016年 | 1501篇 |
2015年 | 1556篇 |
2014年 | 2592篇 |
2013年 | 2269篇 |
2012年 | 2960篇 |
2011年 | 3035篇 |
2010年 | 2201篇 |
2009年 | 2282篇 |
2008年 | 2052篇 |
2007年 | 2464篇 |
2006年 | 2150篇 |
2005年 | 1897篇 |
2004年 | 1521篇 |
2003年 | 1269篇 |
2002年 | 918篇 |
2001年 | 818篇 |
2000年 | 628篇 |
1999年 | 543篇 |
1998年 | 396篇 |
1997年 | 379篇 |
1996年 | 309篇 |
1995年 | 254篇 |
1994年 | 197篇 |
1993年 | 153篇 |
1992年 | 96篇 |
1991年 | 93篇 |
1990年 | 59篇 |
1989年 | 76篇 |
1988年 | 31篇 |
1987年 | 28篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 26篇 |
1983年 | 28篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1975年 | 7篇 |
1963年 | 7篇 |
1959年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Visual evaluation experiments of color discrimination threshold and suprathreshold color‐difference comparison were carried out using CRT colors based on the psychophysical methods of interleaved staircase and constant stimuli, respectively. A large set of experimental data was generated ranged from threshold to large suprathreshold color difference at the five CIE color centers. The visual data were analyzed in detail for every observer at each visual scale to show the effect of color‐difference magnitude on the observer precision. The chromaticity ellipses from this study were compared with four previous published data, of CRT colors by Cui and Luo, and of surface colors by RIT‐DuPont, Cheung and Rigg, and Guan and Luo, to report the reproducibility of this kind of experiment using CRT colors and the variations between CRT and surface data, respectively. The present threshold data were also compared against the different suprathreshold data to show the effect of color‐difference scales. The visual results were further used to test the three advance color‐difference formulae, CMC, CIE94, and CIEDE2000, together with the basic CIELAB equation. In their original forms or with optimized KL values, the CIEDE2000 outperformed others, followed by CMC, and with the CIELAB and CIE94 the poorest for predicting the combined dataset of all color centers in the present study. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 198–208, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20106 相似文献
2.
本文主要介绍了在动态汽车衡的试验过程中不确定度来源,并以动态试验为例重点介绍了计算各分量的标准不确定度、合成标准不确定度以及扩展不确定度的方法. 相似文献
3.
Rudolf Habison 《International Journal of Project Management》1985,3(3):178-181
Meeting time and cost objectives in complex projects involves specific problems and risks. An attempt is made to analyse the components of total cost increase of a project caused by time delay. An outline is given as to how these considerations can be used to estimate cost increases in investors' decision situations as well as to ascertain fair contractual penalties and claims for compensation and for the evaluation of justified project acceleration costs. 相似文献
4.
微波干燥原理及其应用 总被引:31,自引:1,他引:30
介绍了微波干燥的原理和主要特点及其应用的现状,并且给出了微波干燥经济核算的计算方法。 相似文献
5.
We have assessed the antimicrobial, vapor-phase activity of the following natural essential oils (EOs) when used in paraffin-based “active coatings” for paper packaging materials intended to come into contact with foods: clove (Sygzium aromaticum), cinnamon (Cinnamomum zeylanicum), and oregano (Origanum vulgare) EOs, and cinnamaldehyde-enriched cinnamon EO. To our knowledge, this is the first time that such an approach has been presented for consideration by the scientific community. 相似文献
6.
SUSANNA DE CORDT MARC HENDRICKX GEERT MAESMANS PAUL TOBBACK 《International Journal of Food Science & Technology》1992,27(6):661-673
Biphasic and nth-order models were tested as to their usefulness to fit experimental inactivation data of Bacillus licheniformis α-amylase, immobilized on glass beads, and were discussed with respect to their suitability to characterize the considered enzymic system as a time—temperature integrator (TTI) to evaluate heat processes. Both isothermal and non-isothermal inactivation experiments were carried out. Model (kinetic) parameters (rate constant k, activation energy EA and reaction order n) were estimated using a non-linear regression procedure. The results obtained, especially the activation energy of about 293 kJ mole–1 , indicated a potential use of this system as a TTI for heating processes in the temperature range of 96–108°C. 相似文献
7.
����ѡ������Ļ�ɫ���߷��� 总被引:2,自引:0,他引:2
本文根据灰色系统理论中的灰色决策原理,提出了一种合理选择钻机的新方法,并通过了实例验证。结果表明,这种方法切实可行。 相似文献
8.
本文偿试性地应用灰色系统理论中的灰色聚类评估模型,对山东省七个黄金矿山的综合经济效益进行了评价,得出了山东省黄金矿山的综合经济效益较好的合理结论。 相似文献
9.
Klaus Witt 《Color research and application》1994,19(4):273-276
The proposed new color-difference formula of CIE TC 129, which is a modified version of CIELAB, was tested with a recently published data set of textile pass/fail judgments. Goodness of fit is improved, if the parameter of lightness is set near 2, and if, additionally, a weight function for lightness is defined that reduces the weight of a lightness difference with lightness level in relation to chroma or hue scaling. © 1994 John Wiley & Sons, Inc. 相似文献
10.
本文介绍在铀矿床工业指标制定中,对未来矿山开采设计方案及经济计算参数几千问题的分析,以利于合理的制定铀矿床工业指标,为铀矿冶企业技术改造,在建企业修改设计和为选择新建企业提供决策依据,进而使铀矿冶企业提高经济效益。 相似文献