全文获取类型
收费全文 | 601628篇 |
免费 | 9947篇 |
国内免费 | 1769篇 |
专业分类
电工技术 | 10604篇 |
综合类 | 477篇 |
化学工业 | 93098篇 |
金属工艺 | 25817篇 |
机械仪表 | 22423篇 |
建筑科学 | 14763篇 |
矿业工程 | 2976篇 |
能源动力 | 15445篇 |
轻工业 | 52919篇 |
水利工程 | 6031篇 |
石油天然气 | 9984篇 |
武器工业 | 23篇 |
无线电 | 71694篇 |
一般工业技术 | 120269篇 |
冶金工业 | 98696篇 |
原子能技术 | 11538篇 |
自动化技术 | 56587篇 |
出版年
2021年 | 5065篇 |
2020年 | 3807篇 |
2019年 | 4477篇 |
2018年 | 14270篇 |
2017年 | 14788篇 |
2016年 | 11928篇 |
2015年 | 5980篇 |
2014年 | 9357篇 |
2013年 | 25039篇 |
2012年 | 17600篇 |
2011年 | 27873篇 |
2010年 | 23093篇 |
2009年 | 23986篇 |
2008年 | 24204篇 |
2007年 | 25166篇 |
2006年 | 16480篇 |
2005年 | 17996篇 |
2004年 | 15791篇 |
2003年 | 15193篇 |
2002年 | 13895篇 |
2001年 | 13361篇 |
2000年 | 12370篇 |
1999年 | 12735篇 |
1998年 | 29704篇 |
1997年 | 21168篇 |
1996年 | 16475篇 |
1995年 | 12447篇 |
1994年 | 10994篇 |
1993年 | 10786篇 |
1992年 | 8058篇 |
1991年 | 7771篇 |
1990年 | 7433篇 |
1989年 | 7320篇 |
1988年 | 7106篇 |
1987年 | 5893篇 |
1986年 | 5773篇 |
1985年 | 6924篇 |
1984年 | 6409篇 |
1983年 | 5807篇 |
1982年 | 5432篇 |
1981年 | 5591篇 |
1980年 | 5302篇 |
1979年 | 5111篇 |
1978年 | 5040篇 |
1977年 | 5796篇 |
1976年 | 7415篇 |
1975年 | 4496篇 |
1974年 | 4285篇 |
1973年 | 4325篇 |
1972年 | 3627篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
61.
62.
63.
64.
This study investigates the impact of lighting colors on subjective judgments of fabric: in particular, whether the influence of lighting varies depending on fabric types and color combinations. We conducted two visual assessments. In Study 1 (N = 44), eight illuminants and six types of fabric were presented as cloth stimuli. Derived from the literature review, four sets of adjectives (humble-luxurious, cool-warm, old-new, and not preferred-preferred) were used as metrics. In Study 2 (N = 41), five sets of fabric color combination swatches were assessed under lighting conditions that were identical to those of Study 1. Three bipolar scales (ordinary-characterful, classic-modern, and soft-rigid), were employed from factor analysis along with three unipolar scales (luxurious, preferred, harmonious with lighting). The results showed that hue characteristics of lighting and cloth types influenced participants' perceptions of the fabric. Overall, white lighting with 4000 K was the most preferred and luxurious lighting across various types of clothes, while a pinkish white with 4700 K (duv = −0.0127) was the best matched in every color combination. In addition, there were interaction effects between lighting colors, clothes types, and fabric color combinations with regard to each of the perceptual qualities. This study provides empirical evidence for optimally match lighting colors with fabric in the presentation of fabric goods. 相似文献
65.
66.
67.
V. E. Gromov A. M. Glezer K. V. Morozov Yu. F. Ivanov K. V. Volkov 《Russian Metallurgy (Metally)》2015,2015(13):1094-1097
A layer-by-layer analysis of the structures, the phase compositions, and the defect substructures of differentially hardened rails has been carried by optical and transmission electron microscopy. It is found that the material volume of the rail head fillet is cooled faster than the volume located along the central axis. 相似文献
68.
69.
C. Doga Demirhan William W. Tso Joseph B. Powell Efstratios N. Pistikopoulos 《American Institute of Chemical Engineers》2019,65(7):e16498
Current ammonia production technologies have a significant carbon footprint. In this study, we present a process synthesis and global optimization framework to discover the efficient utilization of renewable resources in ammonia production. Competing technologies are incorporated in a process superstructure where biomass, wind, and solar routes are compared with the natural gas-based reference case. A deterministic global optimization-based branch-and-bound algorithm is used to solve the resulting large-scale nonconvex mixed-integer nonlinear programming problem (MINLP). Case studies for Texas, California, and Iowa are conducted to examine the effects of different feedstock prices and availabilities. Results indicate that profitability of ammonia production is highly sensitive to feedstock and electricity prices, as well as greenhouse gas (GHG) restrictions. Under strict 75% GHG reductions, biomass to ammonia route is found to be competitive with natural gas route, whereas wind and solar to ammonia routes require further improvement to compete with those two routes. © 2018 American Institute of Chemical Engineers AIChE J, 65: e16498 2019 相似文献
70.
Loboda P. I. Minitsky A. V. Byba Ye. G. Sysoev M. O. Radchuk S. V. 《Powder Metallurgy and Metal Ceramics》2020,58(11-12):651-656
Powder Metallurgy and Metal Ceramics - The infiltration of aluminum melts into porous metal skeletons produced by powder metallurgy methods, including 3D printing, under a pressure gradient was... 相似文献