全文获取类型
收费全文 | 796篇 |
免费 | 62篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 183篇 |
金属工艺 | 14篇 |
机械仪表 | 35篇 |
建筑科学 | 27篇 |
矿业工程 | 4篇 |
能源动力 | 40篇 |
轻工业 | 176篇 |
水利工程 | 9篇 |
石油天然气 | 3篇 |
无线电 | 36篇 |
一般工业技术 | 108篇 |
冶金工业 | 43篇 |
原子能技术 | 10篇 |
自动化技术 | 162篇 |
出版年
2024年 | 4篇 |
2023年 | 10篇 |
2022年 | 32篇 |
2021年 | 59篇 |
2020年 | 29篇 |
2019年 | 24篇 |
2018年 | 33篇 |
2017年 | 48篇 |
2016年 | 27篇 |
2015年 | 28篇 |
2014年 | 48篇 |
2013年 | 67篇 |
2012年 | 69篇 |
2011年 | 59篇 |
2010年 | 48篇 |
2009年 | 34篇 |
2008年 | 38篇 |
2007年 | 27篇 |
2006年 | 13篇 |
2005年 | 16篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 16篇 |
2000年 | 4篇 |
1999年 | 10篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有861条查询结果,搜索用时 31 毫秒
71.
Okara pellets were dried in a pneumatic tube from 78% of moisture content (w.b.) to 64% and then in a rotational drum to 3%. Time, temperature, and drum rotation were correlated to the okara darkening. The temperatures used were 130, 150, and 170°C in the pneumatic tube and 50, 60, and 70°C in the rotational dryer. The rotations used for the drum were 27 and 47 rpm. When okara was dried only in the pneumatic tube it became dark; however, when dried in both the tube and the dryer the darkening level decreased significantly. The results showed that the first drying level temperature does not influence the drying time of the combined process. 相似文献
72.
Nivia Maria Streit Luisa Helena Rychecki Hecktheuer Marta Weber do Canto Carlos Augusto Mallmann Letícia Streck Thaylise Vey Parodi Liana Pedrolo Canterle 《Food chemistry》2007,102(3):560-564
Erva-mate (Ilex paraguariensis St. Hil.) is a native species from temperate regions of South America, such as Brazil, Paraguay, and Argentina, that is consumed as a beverage known as mate. The objective of this research was to determine the content of caffeic acid, catechin, chlorogenic acid, caffeine, and gallic acid in mate to explain their influence in beverage taste and sensory differences between native and reforested plants, as well as between beverages from plants of different regions of Brazil (Santa Catarina and Rio Grande do Sul states). Compounds were determined by HPLC and results were related to a sensory evaluation performed by trained tasters. Tasters considered the beverage from reforested plants to be more bitter than the beverage from native plants. Beverages from reforested plants had significantly higher caffeic acid and lower catechin, chlorogenic acid, caffeine, and gallic acid content than native plants. Beverages from plants of Santa Catarina state had significantly higher catechin, caffeine, and gallic acid content than plants from Rio Grande do Sul state. 相似文献
73.
Huck U. William; Lisk Robert D.; Parente Eric J.; Principato Deborah E. 《Canadian Metallurgical Quarterly》1986,100(2):128
Four studies with golden hamsters investigated females' acceptance of multiple mating partners. Findings show that females that mated only with a single, recently mated male ran a high risk of pseudopregnancy or reduced litter size. Females paired with males that had mated to satiety 30 min, 8 hrs, or 24 hrs earlier showed a reduced willingness to engage in lordosis than did females paired with a sexually rested (2 wks) male. Females paired with recently mated males were also more likely to mate with additional (fresh) males than were females exposed to rested males. Females presented with 2 anesthetized stimulus males readily discriminated between sexually rested and recently mated individuals. Neither prior sexual experience nor recent copulatory activity was required for this discrimination. It is suggested that multiple-male mating (promiscuity) in female hamsters may be an adaptation against an infertile mating as a consequence of mating with a single, recently mated, sperm-depleted male. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Edson da Costa Bortoni Roberto Alves de Almeida Augusto Nelson Carvalho Viana 《Energy Efficiency》2008,1(3):167-173
This paper presents an optimization framework based on dynamic programming mathematic tool suitable to be implemented in programmable
logic controllers to improve the automated control of parallel pumping loops aiming at energy conservation. The paper also
contributes with simple methods to derive system curve and pumping head-flow speed-dependent characteristic from ordinary
field measurements. 相似文献
75.
Patrick T. Terenzini Alberto F. Cabrera Carol L. Colbeck John M. Parente Stefani A. Bjorklund 《工程教育杂志》2001,90(1):123-130
This study examined the extent to which undergraduate engineering courses taught using active and collaborative learning methods differ from traditional lecture and discussion courses in their ability to promote the development of students' engineering design, problem‐solving, communication, and group participation skills. Evidence for the study comes from 480 students enrolled in 17 active or collaborative learning courses/sections and six traditional courses/sections at six engineering schools. Results indicate that active or collaborative methods produce both statistically significant and substantially greater gains in student learning than those associated with more traditional instructional methods. These learning advantages remained even when differences in a variety of student pre‐course characteristics were controlled. 相似文献
76.
77.
The objective of this paper was to perform an analysis on thermal acceptability in naturally ventilated (NVB) and air-conditioned buildings (ACB) located in hot and humid climates in Brazil. Experiments were carried out in April and November 2005 with 1.301 questionnaires based on ISO 10551:1995(E). Indoor and outdoor climatic variables were monitored simultaneously. The results revealed that 53% of the occupants of NVB and 78% of ACB were thermally satisfied. However, some restrictions were observed with the applications of the following methodologies: ISO/FDIS 7730:2005(E); ANSI/ASHRAE Standard 55:2004; Adaptive Temperature Limits (ATG) and prEN15251: 2005(E). Differences were observed between thermal sensation (TSV) and predicted mean vote (PMV) and between the subject's percentages expressing thermal unacceptability of the environment and the PPD calculated according to ISO/FDIS 7730:2005(E). 相似文献
78.
79.
Given a process y with stationary increments and rational incremental spectral density Φ(s), we parametrize minimal state-space representations of dy. We consider the case when Φ(s) may have zeros on the imaginary axis including infinity and we analyze the zero structure of each state-space representation. 相似文献
80.
Heiderose Herpich Piccoli Antônio Augusto Ulson de Souza Selene Maria Arruda Guelli Ulson de Souza 《臭氧:科学与工程》2015,37(2):170-177
Several samples of knitted cotton fabric in raw state were impregnated with a solution of industrial wetting detergent and treated directly with ozone gas in a closed chamber. Working conditions for the variables: time, pH of the impregnation solution, residual pickup and feed flow rate of oxygen (for ozone generation) were investigated to identify the effects on whiteness degree and fabric strength. The application of ozone proved to be an efficient and promising technology with low water usage. 相似文献