全文获取类型
收费全文 | 6285篇 |
免费 | 148篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 474篇 |
综合类 | 18篇 |
化学工业 | 1718篇 |
金属工艺 | 154篇 |
机械仪表 | 165篇 |
建筑科学 | 204篇 |
矿业工程 | 8篇 |
能源动力 | 264篇 |
轻工业 | 568篇 |
水利工程 | 22篇 |
石油天然气 | 10篇 |
无线电 | 354篇 |
一般工业技术 | 1080篇 |
冶金工业 | 533篇 |
原子能技术 | 232篇 |
自动化技术 | 655篇 |
出版年
2023年 | 32篇 |
2022年 | 54篇 |
2021年 | 100篇 |
2020年 | 57篇 |
2019年 | 67篇 |
2018年 | 83篇 |
2017年 | 73篇 |
2016年 | 124篇 |
2015年 | 88篇 |
2014年 | 163篇 |
2013年 | 369篇 |
2012年 | 201篇 |
2011年 | 342篇 |
2010年 | 288篇 |
2009年 | 329篇 |
2008年 | 343篇 |
2007年 | 294篇 |
2006年 | 228篇 |
2005年 | 245篇 |
2004年 | 199篇 |
2003年 | 191篇 |
2002年 | 189篇 |
2001年 | 129篇 |
2000年 | 118篇 |
1999年 | 136篇 |
1998年 | 238篇 |
1997年 | 169篇 |
1996年 | 126篇 |
1995年 | 84篇 |
1994年 | 115篇 |
1993年 | 102篇 |
1992年 | 72篇 |
1991年 | 87篇 |
1990年 | 63篇 |
1989年 | 87篇 |
1988年 | 72篇 |
1987年 | 56篇 |
1986年 | 82篇 |
1985年 | 70篇 |
1984年 | 64篇 |
1983年 | 65篇 |
1982年 | 77篇 |
1981年 | 59篇 |
1980年 | 49篇 |
1979年 | 50篇 |
1978年 | 47篇 |
1977年 | 36篇 |
1976年 | 50篇 |
1975年 | 23篇 |
1973年 | 19篇 |
排序方式: 共有6459条查询结果,搜索用时 15 毫秒
201.
Hiroshi Fujita 《Microscopy research and technique》1986,3(3):243-304
High voltage electron microscopy has shown numerous advantages for the study of natural science, including biology, but it is especially useful in materials science. The most important advantage for materials science is in-situ experiments on detailed processes of the same phenomena that occur in bulk materials. For such in-situ experiments, the specimens should be thicker than a few microns to observe the behavior of lattice effect. The maximum observable thickness of the specimens and other advantages markedly increase with increasing accelerating voltage, and since 1965, two 3 MV instruments have been installed. The present paper is mainly concerned with these 3 MV electron microscopes and their applications to new research fields. 相似文献
202.
Visual management (VM) has become an important management tool for the smooth management of global supply chains. The target of VM systems is to harmonise communication. For example, in the production sector, VM provides solutions for various issues such as the quick detection of an abnormal situation, continuous maintenance of a safe environment, prevention of an operation miss and knowledge sharing. However, the development of VM cases has been uncontrolled, which is considered problematic. A system for the strategic enhancement of VM is necessary. Recognising this need, this study presents a model for the performance evaluation of relevant cases and validates the utility of the model, which is the initial step in developing a strategic enhancement system for VM. 相似文献
203.
Takayoshi Yokoya Rikiya Yoshida Yuki Utsumi Koji Tsubota Hiroyuki Okazaki Takanori Wakita Yoshikazu Mizuguchi Yoshihiko Takano Takayuki Muro Yukako Kato Hiroshi Kumigashira Masaharu Oshima Hisatomo Harima Yoshihiro Aiura Hitoshi Sato Akihiro Ino Hirofumi Namatame Masaki Taniguchi Masaaki Hirai Yuji Muraoka 《Science and Technology of Advanced Materials》2012,13(5)
We have characterized the electronic structure of FeSe1−xTex for various x values using soft x-ray photoemission spectroscopy (SXPES), high-resolution photoemission spectroscopy (HRPES) and inverse photoemission spectroscopy (IPES). The SXPES valence band spectral shape shows that the 2 eV feature in FeSe, which was ascribed to the lower Hubbard band in previous theoretical studies, becomes less prominent with increasing x. HRPES exhibits systematic x dependence of the structure near the Fermi level (EF): its splitting near EF and filling of the pseudogap in FeSe. IPES shows two features, near EF and approximately 6 eV above EF; the former may be related to the Fe 3d states hybridized with chalcogenide p states, while the latter may consist of plane-wave-like and Se d components. In the incident electron energy dependence of IPES, the density of states near EF for FeSe and FeTe has the Fano lineshape characteristic of resonant behavior. These compounds exhibit different resonance profiles, which may reflect the differences in their electronic structures. By combining the PES and IPES data the on-site Coulomb energy was estimated at 3.5 eV for FeSe. 相似文献
204.
We have developed molecular dynamics codes for a short-range interaction potential that adopt both the flat-MPI and MPI/OpenMP hybrid parallelizations on the basis of a full domain decomposition strategy. Benchmark simulations involving up to 38.4 billion Lennard-Jones particles were performed on Fujitsu PRIMEHPC FX10, consisting of 4800 SPARC64 IXfx 1.848 GHz processors, at the Information Technology Center of the University of Tokyo, and a performance of 193 teraflops was achieved, which corresponds to a 17.0% execution efficiency. Cavitation processes were also simulated on PRIMEHPC FX10 and SGI Altix ICE 8400EX at the Institute of Solid State Physics of the University of Tokyo, which involved 1.45 billion and 22.9 million particles, respectively. Ostwald-like ripening was observed after the multibubble nuclei. Our results demonstrate that direct simulations of multiscale phenomena involving phase transitions from the atomic scale are possible and that the molecular dynamics method is a promising method that can be applied to petascale computers. 相似文献
205.
Maksudul M. Alam Osamu Ito Naoki Sakurar Hiroshi Moriyama 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):1007-1024
Abstract Efficient electron-transfer reactions from three kind of tetraselenafulvalenes (TSeF's) to photoexcited triplet state of C60 or C70 in polar solvents have been confirmed by transient absorption spectroscopy observing the decay of 3C60*/3C70* and rise of C60 ??/C70 ??. Growth of single crystal seems to be stimulated by laser irradiation of the solution containing C60 and bis(ethylenedithio)tetraselena-fulvalene (BEDT-TSeF), in which C60 ?? was effectively formed. 相似文献
206.
207.
208.
Hiroshi Suemasu 《Advanced Composite Materials》2016,25(1):1-18
Analytical efforts to understand problems involving compression after impact (CAI) are reviewed. A theoretical solution of beam plate modeling is introduced to understand the buckling of multiple delaminated plates. Numerical efforts on CAI-related matters for rectangular plates are then briefly described to show the difficulties in evaluating the effects of the various factors on the compressive properties of impact-damaged laminates. Also, the reason for the simplification of the double-spiral damage to multiple circular delaminations is briefly explained from a mechanical viewpoint. Analytical schemes to evaluate the compressive strength of the impact-damaged laminates are introduced based on fracture mechanics. The accuracy and meaning of the solutions are discussed by comparing the present solutions with finite element analysis results. 相似文献
209.
Hiroshi Isakari Kazuki Niino Hitoshi Yoshikawa Naoshi Nishimura 《International journal for numerical methods in engineering》2012,90(4):484-505
Preconditioning methods based on Calderon's formulae for the periodic fast multipole method for elastodynamics in 3D are investigated. Three different types of formulations are proposed. The first type is a preconditioning just by appropriately ordering the coefficient matrix without multiplying preconditioners. The other two types utilise preconditioners constructed using matrices needed in the main fast multipole method algorithms. We make several numerical experiments with proposed preconditioners to confirm the efficiency of these proposed methods. We also conclude that the preconditioning of the first type is faster with respect to the computational time than other preconditioning methods discussed in this article. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
210.
Motonaka Kuroda Yumiko Kato Junko Yamazaki Naoko Kageyama Toshimi Mizukoshi Hiroshi Miyano Yuzuru Eto 《Food chemistry》2012
The determination of the kokumi peptide, γ-glutamyl-valyl-glycine (γ-Glu-Val-Gly) in raw scallop and processed scallop products was carried out using high pressure liquid chromatography–tandem mass spectrometry (LC/MS/MS). The detection of γ-Glu-Val-Gly was achieved using a multiple reaction monitoring (MRM) method. The optimised condition enabled the precise determination of γ-Glu-Val-Gly. Raw scallop contained 0.08 μg/g γ-Glu-Val-Gly, and the γ-Glu-Val-Gly levels in processed scallop products, such as dried-scallop and scallop extract, were measured to be 0.64 and 0.77 μg/g, respectively. This is the first report to confirm the existence of γ-Glu-Val-Gly in foodstuff. 相似文献