全文获取类型
收费全文 | 1429篇 |
免费 | 102篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 598篇 |
金属工艺 | 15篇 |
机械仪表 | 26篇 |
建筑科学 | 38篇 |
矿业工程 | 1篇 |
能源动力 | 53篇 |
轻工业 | 222篇 |
水利工程 | 8篇 |
石油天然气 | 1篇 |
无线电 | 75篇 |
一般工业技术 | 234篇 |
冶金工业 | 119篇 |
原子能技术 | 4篇 |
自动化技术 | 128篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 91篇 |
2021年 | 110篇 |
2020年 | 39篇 |
2019年 | 44篇 |
2018年 | 62篇 |
2017年 | 50篇 |
2016年 | 61篇 |
2015年 | 53篇 |
2014年 | 56篇 |
2013年 | 77篇 |
2012年 | 69篇 |
2011年 | 94篇 |
2010年 | 82篇 |
2009年 | 56篇 |
2008年 | 86篇 |
2007年 | 72篇 |
2006年 | 54篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 31篇 |
2002年 | 26篇 |
2001年 | 19篇 |
2000年 | 20篇 |
1999年 | 14篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1966年 | 2篇 |
排序方式: 共有1533条查询结果,搜索用时 31 毫秒
91.
Ana M. Rule Kellogg J. Schwab Jana Kesavan Timothy J. Buckley 《Aerosol science and technology》2013,47(6):620-628
This study was conducted to evaluate the effect of aerosol generation, relative humidity, and method of sampling on the culturability of the vegetative bacteria Pantoea agglomerans (P. agglomerans) formerly known as Erwinia herbicola. This research has relevance both for the use of this organism as a biowarfare simulant and for bioaerosol exposure assessment and public health. The culturability of P. agglomerans was tested using a test chamber against two generating systems (Collison and Bubble nebulizers), two sampling systems (the all-glass impinger (AGI-30), and the BioSampler), three collection media (water, TSB, and PBS) and across a range of humidities. Results indicated that the Bubble nebulizer was 15% more efficient in generating viable P. agglomerans counts (p ≤ 0.05). No difference was observed in overall efficiency between sampling methods (p > 0.05). However, as a collection media, PBS was observed to yield higher (p ≤ 0.01) viable counts compared to sterile deionized water. Relative humidity was found to strongly influence airborne P. agglomerans culturability. Culturable P. agglomerans was below the limit of detection for RH < 15% and then increased in a log-linear fashion to humidities of 75%. This research will help identify optimal means for evaluation of environmentally sensitive airborne bacteria for purposes of exposure assessment and public health as well as homeland security. 相似文献
92.
Ohne Zusammenfassung 相似文献
93.
N. Khumalo D. Glasser D. Hildebrandt B. Hausberger 《Chemical engineering science》2007,62(10):2765-2776
In a recent paper [Khumalo, N., Glasser, D., Hildebrandt, D., Hausberger, B., Kauchali, S., 2006. The application of the attainable region analysis to comminution. Chemical Engineering Science 61, 5969-5980] it was shown that the attainable region approach could prove useful in designing better comminution circuits. Fundamental to this approach was the assumption that the rate of comminution was only determined by the specific energy within the device. This paper shows experimentally that this assumption holds for a batch ball mill.The system presented here considered breakage of mono-sized feed particles in a laboratory ball mill into two distinct progeny size classes. The population balance model was successfully used to model the experimental products and the results were represented geometrically in a two-dimensional space. The resulting geometric structure can be used to solve process synthesis and optimization problems simultaneously.It was found that the breakage rate parameter out of size class 1 changes with time but exhibits an exponential relationship with an asymptote. It is hypothesized that this asymptote is the rate of breakage at long grind times or in well-mixed, steady-state continuous systems. It is shown that the parameters of the process depend only on the specific energy. This was one of the assumptions that was made in the construction of the attainable region. Thus, equipment selection and operating conditions only require one to match the required specific energy. 相似文献
94.
Jana Dietel 《Information Processing Letters》2008,105(4):121-123
We consider the problem of illuminating a straight line segment with floodlights. The possible locations of the floodlights are given in advance and we want the total size of the floodlights to be minimum. We show that this problem admits a polynomial time algorithm even if we require that no two floodlights are placed at the same location. 相似文献
95.
96.
Alternate oils in fish feeds 总被引:1,自引:0,他引:1
Nearly half of the fish consumed as food worldwide are raised on fish farms rather than caught in the wild, as shown by FAO statistics. The increasing aquaculture of predatory carnivorous fish demands new sources of feed constituents, particularly oils at the moment. Common terrestrial plant oils contain only traces of the long‐chain polyunsaturated fatty acids. In connection with fish feed, especially the lack of n‐3 “marine fatty acids” is obvious. Recommendations on the required amounts of the fatty acids DHA (22:6n‐3) and EPA (20:5n‐3) exist from 1994. When plant oil‐based diets are fed during the growing phase and replaced by a fish oil‐based diet during a period prior to slaughter, most of the beneficial lipid composition of fish in terms of human dietary recommendations is restored. Little attention has been focused on the fish welfare in connection to substitution of dietary oil sources, and studies are still scarce. New fish diets will rely heavily on the use of alternate ingredients such as plant oils also for carnivorous cold‐temperate water fish species. In the future, an addition of synthetic or GMO‐produced “marine” fatty acids is a possible scenario. The aim of this review is to highlight some plant oils used in fish feeds, with special emphasis on compounds other than fatty acids. We also include some results from an ongoing study, where the effect of dietary soy oil on gonad maturation in Atlantic cod (Gadus morhua) is indicated. 相似文献
97.
Among various coating systems for industrial and engineering applications, glass and glass-ceramic coatings have advantages
of chemical inertness, high temperature stability and superior mechanical properties such as abrasion, impact etc as compared
to other coating materials applied by thermal spraying in its different forms viz. PVD, CVD, plasma, etc. Besides imparting
required functional properties such as heat, abrasion and corrosion resistance to suit particular end use requirements, the
glass and glass-ceramic coatings in general also provide good adherence, defect free surface and refractoriness.
Systematic studies covering the basic science of glass and glass-ceramic coatings, the functional properties required for
a particular end-use along with the various fields of application have been reviewed in this paper. 相似文献
98.
99.
100.
Zdeněk Sobalík Kamil Jíša Dalibor Kaucký Alena Vondrová Zdeňka Tvarůžková Jana Nováková 《Catalysis Letters》2007,113(3-4):124-129
The decomposition of nitrous oxide was studied over Fe-ferrierite, Me-ferrierites and Fe/Me-ferrierites (Me: Pt, Rh and Ru).
Flow as well as batch experiments were carried out and showed a synergy between Fe and Me ions. Ions of noble metals in Fe-ferrierite
increased the catalytic activity in the sequence Pt < Rh ≅ Ru. Addition of NO substantially decreased the decomposition of
N2O over Rh/ferrierite and Ru/ferrierite, but not over bimetallic ferrierites. NO
x
species created during the decomposition of nitrous oxide alone as well as with addition of NO, and employment of nitrous
oxide labeled with 18O allowed us to assume a changing decomposition mechanism in the presence of Me ions in Fe-ferrierites. 相似文献