全文获取类型
收费全文 | 267篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 19篇 |
综合类 | 2篇 |
化学工业 | 69篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 13篇 |
能源动力 | 6篇 |
轻工业 | 15篇 |
水利工程 | 4篇 |
无线电 | 20篇 |
一般工业技术 | 56篇 |
冶金工业 | 21篇 |
原子能技术 | 27篇 |
自动化技术 | 19篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1981年 | 7篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有278条查询结果,搜索用时 0 毫秒
141.
We report first-principles calculations of the structure, elastic properties, lattice dynamics and some thermodynamic properties of Mg2Si and Mg2Ge compounds. The fully relaxed structure parameters and elastic stiffness constants of Mg2Si and Mg2Ge compounds are in good agreement with previous experimental data. The linear response method is applied to determine the phonon dispersion relations, phonon density of states, and Born effective charge. The computed thermodynamic properties such as vibrational entropy, constant-volume specific heat, and Debye temperature coincide with previous experimental data. 相似文献
142.
Direct Evidence for Structural Transition Promoting Shear Thinning in Cylindrical Colloid Assemblies
Kazuhiro Shikinaka Keisuke Kaneda Saori Mori Tei Maki Hiroyasu Masunaga Yoshihito Osada Kiyotaka Shigehara 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(9):1813-1820
In this paper, we describe stimuli‐responsive hydrogels prepared from a rigid rod‐like polyelectrolyte ‘imogolite’ and a dicarboxylic acid. The hydrogel exhibited thixotropy in response to mechanical shock within the order of seconds or sub‐seconds. Here, using the latest structural/rheological characterisation techniques, the relationship between the structural transition processes and the shear thinning was estimated. The evidence obtained by the experiments revealed for the first time the direct relationship between the microscopic structural change and the macroscopic thixotropic behavior that have been extensively discussed. The thixotropic hydrogel has the hierarchical architecture in the combination of imogolite and dicarboxylic acid, i.e., sheathed nanotubes/hydroclusters of cross‐bridged nanotubes/frameworks. The formation and disintegration of the network structure upon resting and agitating, respectively, were the origin of gel/sol transition (thixotropy), although the hydroclusters of cross‐bridged nanotubes were maintained throughout the transition. 相似文献
143.
Hiroyasu Mochizuki 《Nuclear Engineering and Design》2000,200(1-2)
The Advanced Thermal Reactor (ATR), a boiling-water-cooled, heavy-water-moderated, pressure-tube type reactor, has a series of check-valves just upstream of a water drum that serves as a distributing header for fuel channels. In the case of a hypothetical guillotine break upstream of the water drum, the check-valve integrity is a key issue for reactor safety during rapid closure. Pipe break experiments adjacent to and far from the water drum were conducted to measure the deformation of the valve and the water hammer behavior. Fastest disk impact was observed in the case of an adjacent break and water hammer was observed in the case of a break far from the valve. An evaluation method of valve integrity after the rapid closure to be taken over by the simple method is proposed. In the present study, the thermal-hydraulic analysis is conducted using the HITSL code with a dynamic check-valve model, and structural analysis is conducted by the DYNA3D code. Both behaviors relating thermal-hydraulics and structure are traced by these codes. 相似文献
144.
Kazuya Sakamoto Yoshinori Takashima Hiroyasu Yamaguchi Akira Harada 《Synthetic Metals》2009,159(9-10):977-981
2T-βCD2 and 3T-βCD2, which have bithiophene (2T) and terthiophene (3T) with β-cyclodextrin (CD) at each end form supramolecular assemblies in aqueous solutions. These supramolecular assemblies were characterized by NMR, UV, fluorescence spectroscopy, circular dichroism spectroscopy, and atomic force microscope (AFM). Supramolecular assemblies from 3T-βCD2 form orientated structures due to their π–π stacking ability. AFM images of the supramolecular assembly incorporating 3T-βCD2 showed fibrous objects on mica substrates. 相似文献
145.
146.
147.
148.
149.
An aqueous DNA solution was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from a spiked soil. Solubilities of 0.56, 11.78, and 11.24 mg L(-1) for anthracene, phenanthrene, and pyrene, respectively, were achieved after 1 day equilibration in 1% DNA. Using a spiked soil that contained 72 mg kg(-1) anthracene, 102 mg kg(-1) phenanthrene, and 99 mg kg(-1) pyrene, extractions of close to 88, 78, and 94%, respectively, were attained with 5% DNA at a 1:50 soil/extractant ratio. Maximum PAH dissolution occurred after 4-6 h. Comparative tests showed the main advantage of DNA over methyl-beta- and gamma-cyclodextrins and Tween 80 for pyrene removal. An ionic strength of 0.1 M NaCl was found necessary for maximum PAH dissolution and extraction. The performance of hexane regenerated DNA also remained stable after three stages of recycling. These results show the huge potential of DNA as an aqueous washing agent for PAH-contaminated soil. 相似文献
150.
Murakami M Sato H Taketomi Y Yamamoto K 《International journal of molecular sciences》2011,12(3):1474-1495
Mammalian genomes encode genes for more than 30 phospholipase A(2)s (PLA(2)s) or related enzymes, which are subdivided into several subgroups based on their structures, catalytic mechanisms, localizations and evolutionary relationships. More than one third of the PLA(2) enzymes belong to the secreted PLA(2) (sPLA(2)) family, which consists of low-molecular-weight, Ca(2+)-requiring extracellular enzymes, with a His-Asp catalytic dyad. Individual sPLA(2) isoforms exhibit unique tissue and cellular localizations and enzymatic properties, suggesting their distinct pathophysiological roles. Recent studies using transgenic and knockout mice for several sPLA(2) isoforms, in combination with lipidomics approaches, have revealed their distinct contributions to various biological events. Herein, we will describe several examples of sPLA(2)-mediated phospholipid metabolism in vivo, as revealed by integrated analysis of sPLA(2) transgenic/knockout mice and lipid mass spectrometry. Knowledge obtained from this approach greatly contributes to expanding our understanding of the sPLA(2) biology and pathophysiology. 相似文献