全文获取类型
收费全文 | 801篇 |
免费 | 19篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 208篇 |
金属工艺 | 22篇 |
机械仪表 | 14篇 |
建筑科学 | 22篇 |
能源动力 | 14篇 |
轻工业 | 39篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 42篇 |
一般工业技术 | 128篇 |
冶金工业 | 179篇 |
原子能技术 | 21篇 |
自动化技术 | 116篇 |
出版年
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 37篇 |
2012年 | 14篇 |
2011年 | 51篇 |
2010年 | 33篇 |
2009年 | 34篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 27篇 |
2003年 | 25篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 17篇 |
1999年 | 25篇 |
1998年 | 65篇 |
1997年 | 33篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 21篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1971年 | 4篇 |
1968年 | 3篇 |
排序方式: 共有820条查询结果,搜索用时 15 毫秒
1.
2.
S. Brabetz R. Weidl F. Klemm L. Dörrer F. Schmidl P. Seidel 《Journal of Low Temperature Physics》1997,106(3-4):527-532
We investigated different types of high-Tc DC-SQUID gradiometers with the aim to develop an one-channel heart monitoring system for non-invasive measurements in unshielded
environment. This system could be used to obtain information about the patients condition in serial examinations and in emergency
cases fast and stable. Step-edge and bicrystal Josephson junctions were used to prepare planar galvanically coupled thin film
gradiometers and magnetometers. These sensors were used to carry out measurements in well-shielded and non-shielded environment
and we compared the different noise properties and field gradient resolutions. With different types and sizes of high-Tc DC-SQUID sensors magnetocardiograms were measured in a magnetically shielded room. The influence of antenna configurations,
SQUID parameters, and cooling conditions on the measurement of magnetocardiograms will be discussed. We investigated possibilities
to suppress the earth magnetic field (with pairs of Helmholtz coils) and for noise field compensation in unshielded environment. 相似文献
3.
Agnieszka J. Klemm Piotr Klemm Kazimierz Rozniakowski Tomasz W. Wojtatowicz 《Building and Environment》2002,37(12):1233-1240
This paper presents the results of the larger study into a potential application of laser radiation for the detection of phase transition processes in low temperatures occurring on the surface layers of cementitious materials. An attempt was made to identify relationships between the environmental conditions—temperature and air humidity, and the selected parameters of the reflected light. Onset of the condensation process and formation of water microdrops on the surface of the material leads to the phase displacement of individual laser rays, which are represented by different speckle images.
Although the analysis of parameters of the reflected light are very difficult in the case of porous materials because of highly developed roughness of the surface structure it has been proved that a dynamic study of the phase transition phenomena can be successfully carried out without mechanical intervention. 相似文献
4.
Agnieszka J Klemm Piotr Klemm Kazimierz Rozniakowski Tomasz W Wojtatowicz 《Building and Environment》2002,37(12):1221-1232
This paper present the results of the investigation into a potential application of laser radiation for the detection of phase transition processes occurring on the surface layers of porous materials. An attempt was made to discuss in the approximation equations, the relationships between coefficients of the reflected light, the temperature and humidity of the surrounding environment. Laser light reflected from the porous surface carries information about the roughness of the structure. The presence of water microdrop on the surface of the porous material, as a result of condensation and thus a phase transition, leads to the phase displacement of individual rays, which is represented by different images. Therefore, a comprehensive analysis of the reflected light parameters allows a dynamic study of the phase transition phenomena without mechanical intervention. 相似文献
5.
6.
All boiling water reactor (BWR) degraded core experiments performed prior to CORA-33 were conducted under ‘wet’ core degradation conditions, in which water remains within the core and continuous steaming feeds metal-steam oxidation reactions on the in-core metallic surfaces. However, one dominant set of accident scenarios would occur with reduced metal oxidation under ‘dry’ core degradation conditions and, prior to CORA-33, this set had been neglected experimentally. The CORA-33 experiment was designed specifically to address this dominant set of BWR ‘dry’ core severe accident scenarios and to resolve partially phenomenological uncertainties concerning the behavior of relocating metallic melts that drain into the lower regions of a ‘dry’ BWR core (the ex-reactor experiments at Sandia National Laboratories will further address these uncertainties). CORA-33 was conducted on 1 October 1992, in the CORA test facility at Karlsruhe. A review of the CORA-33 data indicates that the objectives were achieved; i.e. core degradation occurred at a core heat-up rate (characterized by the absence of any temperature escalation caused by oxidation) and a test section axial temperature profile (at incipient structural melting) that are prototypic of full-core nuclear power plant simulations under ‘dry’ core conditions. Simulations of the CORA-33 test at Oak Ridge National Laboratory (ORNL) have required the modification of existing control blade-canister materials interaction models to include the eutectic melting of the stainless steel-zircaloy interaction products and the heat of mixing of stainless steel and zircaloy. The timing and location of canister failure and melt intrusion into the fuel assembly appear to be adequately simulated by the ORNL models. This paper will present the results of the post-test analyses carried out at ORNL based on the experimental data and the post-test examination of the test bundle at Karlsruhe. The implications of these results with respect to degraded core modelling and the associated safety issues are also discussed. 相似文献
7.
8.
Obermaier H Mohring J Deines E Hering-Bertram M Hagen H 《IEEE transactions on visualization and computer graphics》2012,18(2):270-282
Crease surfaces describe extremal structures of 3D scalar fields. We present a new region-growing-based approach to the meshless extraction of adaptive nonmanifold valley and ridge surfaces that overcomes limitations of previous approaches by decoupling point seeding and triangulation of the surface. Our method is capable of extracting valley surface skeletons as connected minimum structures. As our algorithm is inherently mesh-free and curvature adaptive, it is suitable for surface construction in fields with an arbitrary neighborhood structure. As an application for insightful visualization with valley surfaces, we choose a low frequency acoustics simulation. We use our valley surface construction approach to visualize the resulting complex-valued scalar pressure field for arbitrary frequencies to identify regions of sound cancellation. This provides an expressive visualization of the topology of wave node and antinode structures in simulated acoustics. 相似文献
9.
König Till Hagen S. P. Virtanen S. Galetz M. C. 《Metallurgical and Materials Transactions A》2022,53(11):4023-4033
Metallurgical and Materials Transactions A - Co-based superalloys have been developed as candidate materials to replace Ni-based superalloys in hot sections of turbine engines, however, their... 相似文献
10.
Dehydrogenation of Light Alkanes Over Rhenium Catalysts on Conventional and Mesoporous MFI Supports 总被引:1,自引:0,他引:1
Anne Krogh Rovik Anke Hagen Iver Schmidt Søren Dahl Ib Chorkendorff Claus Hviid Christensen 《Catalysis Letters》2006,109(3-4):153-156
Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K
and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing
amounts of ethene were produced with time on stream due to deactivation of the catalyst. We show that by use of rhenium impregnated
MFI supports with very few or no acidic sites (Si/Al > 500), highly selective ethane dehydrogenation catalysts are obtained
with ethene selectivities of 98%. By use of mesoporous MFI supports (Si/Al >500) the lifetime of the catalyst appears to be
slightly improved compared to conventional MFI crystals. The beneficial effect of a mesoporous MFI support is convincingly
demonstrated in propane dehydrogenation, where both conversion and selectivities on the mesoporous MFI (Si/Al > 500) impregnated
with Re are significantly higher than on Re supported on a comparable conventional MFI support. 相似文献