全文获取类型
收费全文 | 2419篇 |
免费 | 70篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 5篇 |
化学工业 | 969篇 |
金属工艺 | 41篇 |
机械仪表 | 41篇 |
建筑科学 | 201篇 |
矿业工程 | 6篇 |
能源动力 | 66篇 |
轻工业 | 189篇 |
水利工程 | 16篇 |
石油天然气 | 2篇 |
武器工业 | 4篇 |
无线电 | 126篇 |
一般工业技术 | 313篇 |
冶金工业 | 154篇 |
原子能技术 | 33篇 |
自动化技术 | 304篇 |
出版年
2022年 | 22篇 |
2021年 | 52篇 |
2020年 | 30篇 |
2019年 | 27篇 |
2018年 | 34篇 |
2017年 | 25篇 |
2016年 | 63篇 |
2015年 | 56篇 |
2014年 | 58篇 |
2013年 | 116篇 |
2012年 | 90篇 |
2011年 | 120篇 |
2010年 | 99篇 |
2009年 | 105篇 |
2008年 | 99篇 |
2007年 | 86篇 |
2006年 | 93篇 |
2005年 | 80篇 |
2004年 | 63篇 |
2003年 | 45篇 |
2002年 | 51篇 |
2001年 | 47篇 |
2000年 | 53篇 |
1999年 | 63篇 |
1998年 | 58篇 |
1997年 | 61篇 |
1996年 | 54篇 |
1995年 | 56篇 |
1994年 | 44篇 |
1993年 | 31篇 |
1992年 | 40篇 |
1991年 | 42篇 |
1990年 | 32篇 |
1989年 | 40篇 |
1988年 | 26篇 |
1987年 | 31篇 |
1986年 | 29篇 |
1985年 | 26篇 |
1984年 | 30篇 |
1983年 | 27篇 |
1982年 | 17篇 |
1981年 | 30篇 |
1980年 | 23篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 22篇 |
1976年 | 21篇 |
1975年 | 18篇 |
1974年 | 21篇 |
1973年 | 19篇 |
排序方式: 共有2491条查询结果,搜索用时 10 毫秒
51.
Manfred Schulz Gerd West Sakum Ourk Ingo Strunz 《Advanced Synthesis \u0026amp; Catalysis》1980,322(2):295-304
Azoperoxides. VI. Selective Decomposition of β-Azoacylperoxides The selective decomposition of the O O-Groups in the azoperoxides 1 and 2 is possible by reaction with dimethylaniline at 35°C. Rate constants were measured and the decomposition products were analyzed. Intermediates are azoalkyl radicals. The radical yield of the amine induced decomposition of 2 in ethylbenzene is 8.2% at 35°C. UV irradiation of the azoperoxides 1 and 2 at 20°C in ethylbenzene results in a quantitative and selective decomposition of the azo groups. Intermediates are C-radicals with intact peroxide groups. The reaction of 1 and 2 with triethylstannane yields reduction products of the O O-groups and the NN-groups, respectively. 相似文献
52.
53.
Manfred Jeitler 《控制论与系统》2013,44(3-4):315-333
This article gives an introduction into the current understanding of time invariance and evidence of its violation in experimental particle physics. The connection between time invariance and other discrete symmetries, particularly, CP-invariance, is explained. The first experimental determination of CP-violation is explained, and recent experiments on CP-violation and on T-violation are discussed. 相似文献
54.
Andreas Menrad Thomas Goedecke Klaus‐Peter Gruender Manfred H. Wagner 《Packaging Technology and Science》2013,26(6):311-326
The effect of the wall thickness variation of blow‐moulded bodies made of high‐density polyethylene on an internal pressure test after prestoring the packaging with standard liquids was evaluated in experiments and simulations. The objects of the investigation were jerrycans used for the transportation and storage of dangerous goods. The wall thickness was determined using two alternative methods to the magnetostatic measurement. These alternative methods are used for research purpose to get a volumetric model of the jerrycan wall as a geometric model for the simulation. The comparison of the experiments and the simulations of the internal pressure test were performed using the digital image correlation method. The integral strain and deformation of the whole jerrycan was detected by measuring the total mass of the jerrycan being filled with water during the internal pressure test. This is a suitable alternative to the optical measurements of local deformation by the digital image correlation method. Prestorage at 40 °C without the influence of chemicals strengthens the jerrycan, whereas the swelling effect of butyl acetate and hydrocarbon mixture softens the jerrycan. The comparison with the experiment is necessary to verify the accuracy of the simulation. It shows that the deformation can be simulated more precisely by using the actual measured geometry. The weakening of the high‐density polyethylene caused by a hydrocarbon mixture can be simulated using the Arrhenius equation. The aim of the simulation was to discover whether it is possible to use specimens to predict the behaviour of a packaging both after the influence of standard liquids. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
55.
Marco Deluca Raúl Bermejo Martin Pletz Manfred Wießner Peter Supancic Robert Danzer 《Journal of the European Ceramic Society》2012,32(16):4371-4380
Miniaturised silicon-based multilayer chips are nowadays widespread as semiconductor components for the mobile device technology. The use of special processing and integration procedures requires such materials to possess a definite mechanical strength to ensure the functionality of the entire device. The strength and mechanical reliability of such components can be described by the Weibull theory, and is highly influenced by the geometry of the metallisation and other near-surface functional layers. In this work, we attempt to clarify the mechanisms leading to the failure of the metallised side of Si-chip components. The combined use of Finite Elements (FE) and Focused Ion Beam (FIB) analyses allowed recognising that cracks are induced in the metal-oxide-silicon interfacial area well before complete failure of the component. Such cracks have a crucial role in the lower strength and higher Weibull modulus observed on the metallised side. 相似文献
56.
57.
Franz Tscheikner-Gratl Robert Sitzenfrei Wolfgang Rauch Manfred Kleidorfer 《Structure and Infrastructure Engineering》2016,12(3):366-380
In the past decades, the main focus of water supply management has moved from construction of new water supply networks to rehabilitation and adaptation of the existing infrastructure. The decision-making process for the rehabilitation management relies heavily on the quality of the applied deterioration model. A recurring problem in the application of such models relates to the quality and availability of network data. These data are often incomplete or unreliable because building measures and damages are only documented properly recently and the recovery of older data is difficult and expensive. A key point in rehabilitation planning is therefore data collection and data reconstruction. Consequently, the aim of this paper is to present a methodology for the enhancement of the available data of water supply networks and the prognosis of the necessary rehabilitation rates under limited data availability. Results indicate that the presented data reconstruction technique has advantages as compared to traditional data extrapolation. It also allows the reconstruction of fragmentary data about existing water supply and wastewater collection systems for the operating utilities. However, it cannot be used for reconstructing failure types as well as the whole information on pipes (e.g. more than two missing information). 相似文献
58.
Francesco Alessandro Cuzzola Manfred Morari 《International journal of control》2013,86(16-17):1293-1301
In this paper we investigate some analysis and control problems for discrete-time hybrid systems in the piece-wise affine form. By using arguments from the dissipativity theory for non-linear systems, we show that H X analysis and synthesis problems can be formulated and solved via linear matrix inequalities by taking into account the switching structure of the considered system. In this paper we address the generalized problem of controlling hybrid systems whose switching structure does not depend only on the state but also on the control input. 相似文献
59.
Joseph X. Kugbe Fosu Mathias Tamene L. Desta Manfred Denich Paul L. G. Vlek 《Nutrient Cycling in Agroecosystems》2012,93(3):265-284
This study has assessed the seasonal occurrence of annual vegetation fires and defined inter-seasonally burned area for the different vegetation cover types across Ghana and the northern region of Ghana using 10-year (2001?C2010) remote sensing data. These values were used with fire induced elemental losses to estimate greenhouse gas emissions and net plant nutrient loss due to gross bush fire nutrient transfers and annual atmospheric nutrient depositions. About 21, 68, 10 and 1?% of annual burns across the northern region of Ghana take place in the months of November, December, January and February respectively. As much as 68?±?4 thousand km2 (25?C32?%) and 37?±?2.6 thousand km2 (46?C60?%) of dry land are annually burned across Ghana and the northern region of Ghana respectively, with 53?C56?% of the total annual burns across the country taking place in the northern region. About 10,100?C28,400 Gg of C, comprising 215?C4,700 thousand Gg of CO2 equivalent (CO2, CH4) potential global warming green house gases and 48?C324 thousand Gg of local pollutants (CO, NOx) are estimated to be released annually through bush fire occurrence across Ghana. Net negative balance for P between fire-induced nutrient transfers and, annual wet and dry nutrient deposits is of concern given the high P-sorbing mineral content of the soils. The temporal loss of P suggest an input source than wet and dry atmospheric P depositions for the sustenance of the ecosystem or predict a long term threat to regional food production. 相似文献
60.