全文获取类型
收费全文 | 1411篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 32篇 |
综合类 | 5篇 |
化学工业 | 329篇 |
金属工艺 | 31篇 |
机械仪表 | 33篇 |
建筑科学 | 74篇 |
矿业工程 | 5篇 |
能源动力 | 26篇 |
轻工业 | 116篇 |
水利工程 | 1篇 |
无线电 | 97篇 |
一般工业技术 | 231篇 |
冶金工业 | 315篇 |
原子能技术 | 21篇 |
自动化技术 | 129篇 |
出版年
2021年 | 14篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 14篇 |
2014年 | 27篇 |
2013年 | 44篇 |
2012年 | 33篇 |
2011年 | 61篇 |
2010年 | 39篇 |
2009年 | 36篇 |
2008年 | 55篇 |
2007年 | 48篇 |
2006年 | 45篇 |
2005年 | 41篇 |
2004年 | 29篇 |
2003年 | 28篇 |
2002年 | 26篇 |
2001年 | 33篇 |
2000年 | 17篇 |
1999年 | 32篇 |
1998年 | 61篇 |
1997年 | 67篇 |
1996年 | 41篇 |
1995年 | 36篇 |
1994年 | 36篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1981年 | 24篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 22篇 |
1976年 | 29篇 |
1975年 | 18篇 |
1973年 | 25篇 |
1972年 | 14篇 |
1971年 | 14篇 |
1970年 | 16篇 |
1969年 | 15篇 |
1968年 | 19篇 |
排序方式: 共有1445条查询结果,搜索用时 31 毫秒
51.
52.
53.
Design and Fabrication of TES Detector Modules for the TIME-Pilot [CII] Intensity Mapping Experiment
54.
Jinyang Chung Ee Taek Hwang Haemin Gang Man Bock Gu 《Reactive and Functional Polymers》2013,73(1):39-45
Uniform magnetic separable robust microbeads using a branched polymer were successfully developed for stable enzyme immobilization. The changed morphology of the microbeads was shown by scanning electron microscopy (SEM) analysis. The aldehyde groups on the polymers and imine groups derived from the Schiff base reaction between the aldehyde and amine moiety were found as the evidence of these reactions based on Fourier transform infrared (FT-IR) spectroscopy. The amine groups of the enzyme react with the aldehyde groups on the glutaraldehyde polymer so that the stable conjugations are formed. The specific activity of the conjugated enzyme was found to be retained more than 50%, but the reaction rate constant, Km value was not changed, compared to the free enzyme. In addition, the enzyme conjugated in the microbeads was found to be highly stable for more than 50 days, pertaining over 60% of its initial activity, even after being reused more than 15 times repeatedly. Furthermore, the magnetic-driven controllability provided facile separable characters for the repeated recycling. It is expected that these microbeads can be utilized as a key tool for successful realization not only in enzymatic conversion processes but also in extended fields; bio-based sensors or analytical devices, bioprocessing, bioremediation, to name only a few of numerous areas. 相似文献
55.
David Wenger Wolfgang Polifke Eberhard Schmidt-Ihn Tarek Abdel-Baset Steffen Maus 《International Journal of Hydrogen Energy》2009
In recent years, significant research and development efforts were spent on hydrogen storage technologies with the goal of realizing a breakthrough for fuel cell vehicle applications. This article scrutinizes design targets and material screening criteria for solid state hydrogen storage. Adopting an automotive engineering point of view, four important, but often neglected, issues are discussed: 1) volumetric storage capacity, 2) heat transfer for desorption, 3) recharging at low temperatures and 4) cold start of the vehicle. The article shall help to understand the requirements and support the research community when screening new materials. 相似文献
56.
57.
Jason B. K. Pang Marc O. Eberhard John F. Stanton 《Canadian Metallurgical Quarterly》2010,15(3):231-239
A new beam-to-column connection has been developed for assembling precast concrete bridge bents in regions of high seismicity. The connection is made with a small number of large column bars, which are grouted into large corrugated-metal ducts embedded in the cap beam. Bents built with these connections can be erected quickly and permit generous construction tolerances. To evaluate the seismic performance of the proposed connection, lateral-load tests were performed on three manifestations of the connection, as well as on a comparable cast-in-place connection. The tests demonstrated that the force-displacement response and damage progression in the precast connection are similar to those of typical cast-in-place concrete connections. Deliberate partial debonding of the longitudinal reinforcement only slightly affected the force-displacement response and observed damage. 相似文献
58.
This paper introduces a general decomposition scheme for single stage scheduling problems with jobs that have arbitrary release
dates. We assume that the objective function is monotone in the completion time of each job. The decomposition scheme has
significant theoretical and practical relevance. When assuming equal processing times, we can reduce the number of steps required
to solve several well-known nonpreemptive single machine scheduling problems by O(n3)\mathcal{O}(n^{3}), provided the processing time p is constant. Specifically, we develop new approaches that solve the problems 1|r
i
,p
i
=p|∑f
i
(C
i
) and 1|r
i
,p
i
=p|∑w
i
U
i
in O(n4)\mathcal{O}(n^{4}) time; the algorithms that have been described in the literature for these problems operate in O(n7)\mathcal{O}(n^{7}). Moreover, solution approaches for NP\mathcal{NP}-hard problems with unequal processing times may also benefit from our decomposition rule. This is particularly true if p
max/p
min is close to 1. Using the decomposition rule, either the problem size is reduced or additional information about the maximal
schedule length is obtained. 相似文献
59.
Investigations on metal-cutting machining processes that were conducted since the second half of the twentieth century have
considerably contributed to disclosing the principles underlying the cutting process. Although numerous studies have been
carried out on this subject, a generally valid model of the cutting process and the interactions in the separating processes
does not exist yet. Such a model could guarantee the disclosure of the principles of thermodynamic interactions between the
cutting process and the involved machine structure. This contribution is twofold and presents an experimental setup used to
determine cutting forces and temperatures in orthogonal cutting processes. The results are then used as a reference for simulations
made with the Discrete Element Method (DEM). The DEM is due to its meshless nature well suited to capture large deformations
and rupture of material which is included very naturally. It is examined to which extent the measured results can be captured
with the DEM model. 相似文献
60.
Ho Jin Ryu Byoung Oon Lee Seok Jin Oh Jun Hwan Kim Chan Bock Lee 《Journal of Nuclear Materials》2009,392(2):206-61
Diffusion couple tests of U-Zr or U-Zr-Ce alloys vs. ferritic martensitic steels such as HT9 or T91 were carried out in order to evaluate the performance of the diffusion barrier candidates. Elemental metal foils of Zr, Nb, Ti, Mo, Ta, V and Cr were very effective in inhibiting interdiffusion between these fuels and steels. Eutectic melting between the fuels and steels was not observed in any of the diffusion couples using these diffusion barrier foils at annealing temperatures up to 800 °C. Among the metallic foils evaluated in this study, V and Cr exhibited the most promising performances as a diffusion barrier material for eliminating the fuel cladding chemical interaction problem. However, Zr, Nb and Ti showed an active interaction with the fuel mainly due to the large U solubility. 相似文献