全文获取类型
收费全文 | 560篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 60篇 |
化学工业 | 160篇 |
金属工艺 | 12篇 |
机械仪表 | 12篇 |
建筑科学 | 5篇 |
能源动力 | 37篇 |
轻工业 | 40篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 62篇 |
一般工业技术 | 70篇 |
冶金工业 | 45篇 |
原子能技术 | 14篇 |
自动化技术 | 70篇 |
出版年
2023年 | 13篇 |
2022年 | 23篇 |
2021年 | 38篇 |
2020年 | 23篇 |
2019年 | 17篇 |
2018年 | 26篇 |
2017年 | 18篇 |
2016年 | 30篇 |
2015年 | 13篇 |
2014年 | 29篇 |
2013年 | 42篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 24篇 |
2008年 | 25篇 |
2007年 | 12篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 22篇 |
1997年 | 18篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有589条查询结果,搜索用时 0 毫秒
141.
142.
143.
Tatsuya Kawada Tomohisa Masumitsu Yuta Kimura Satoshi Watanabe Shin-ichi Hashimoto Keiji Yashiro Koji Amezawa 《Journal of Electroceramics》2014,32(1):78-85
Effect of mechanical stress on defect equilibrium was studied with an oxygen nonstoichiometric compound, La0.6Sr0.4Co0.2Fe0.8O3-δ . In general, formation of oxygen vacancy in an oxide causes lattice expansion, which leads to stabilization of oxygen vacancy in the material under a tensile stress, and vice versa. Oxygen vacancy concentration is thus expected to increase under a tensile stress and decrease under a compressive stress. However, the change in defect concentration would not proceed spontaneously so that the material just after the application of stress would stay out of equilibrium. On this assumption, attempts were made to detect the shift of oxygen potential under stress using a potentiometric method. A ball-shaped yttria stabilized zirconia (YSZ) of 9.5 mm in diameter was utilized as an oxygen potential sensor as well as a pushing rod which was pressed onto the sample surface. In the measurements at 873 K to 1073 K, a clear shift of emf to the negative direction was observed depending on the magnitude of load and loading speed. It was followed by a relaxation to the initial value under the stress. On unloading operation, the shift of emf to the positive direction was observed. Those behaviors were well explained by the assumption that the oxygen vacancy concentration varies under mechanical stress. 相似文献
144.
Hirohiko Houjou Masakazu Kamura Yuta Nagano Muneyuki Ito Shigeru Aomori Masahito Oh-e 《Organic Electronics》2013,14(12):3472-3476
Dinuclear and trinuclear cobalt (III) complexes were prepared using fused salphen ligands that have the same number of benzene rings along the major axis of the molecules. The two compounds were used as organic thin film formed on a glass or a SiO2/n-Si substrate for investigating electronic conductivity and transistor characteristics, respectively. The conductivity of di- and trinuclear complexes were 8.5 × 10−5 and 5.8 × 10−3 S cm−1, meaning that the increment of the nuclearity from two to three resulted in multiplication of 70 times. The thin film of the trinuclear complex showed a faint transistor activity, where the thin film act as n-type semiconductor. In contrast, the dinuclear complex did not afford a detectable response to the gate voltage. 相似文献
145.
Yukino Ogura Kazuko Tajiri Nobuyuki Murakoshi DongZhu Xu Saori Yonebayashi Siqi Li Yuta Okabe Duo Feng Yuzuno Shimoda Zoughu Song Haruka Mori Zixun Yuan Kazutaka Aonuma Masaki Ieda 《International journal of molecular sciences》2021,22(2)
Neutrophils are recruited into the heart at an early stage following a myocardial infarction (MI). These secrete several proteases, one of them being neutrophil elastase (NE), which promotes inflammatory responses in several disease models. It has been shown that there is an increase in NE activity in patients with MI; however, the role of NE in MI remains unclear. Therefore, the present study aimed to investigate the role of NE in the pathogenesis of MI in mice. NE expression peaked on day 1 in the infarcted hearts. In addition, NE deficiency improved survival and cardiac function post-MI, limiting fibrosis in the noninfarcted myocardium. Sivelestat, an NE inhibitor, also improved survival and cardiac function post-MI. Flow cytometric analysis showed that the numbers of heart-infiltrating neutrophils and inflammatory macrophages (CD11b+F4/80+CD206low cells) were significantly lower in NE-deficient mice than in wild-type (WT) mice. At the border zone between intact and necrotic areas, the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells was lower in NE-deficient mice than in WT mice. Western blot analyses revealed that the expression levels of insulin receptor substrate 1 and phosphorylation of Akt were significantly upregulated in NE-knockout mouse hearts, indicating that NE deficiency might improve cardiac survival by upregulating insulin/Akt signaling post-MI. Thus, NE may enhance myocardial injury by inducing an excessive inflammatory response and suppressing Akt signaling in cardiomyocytes. Inhibition of NE might serve as a novel therapeutic target in the treatment of MI. 相似文献
146.
147.
Ikuya Kinefuchi Yusuke Kotsubo Kenichi Osuka Yuta Yoshimoto Nobuya Miyoshi Shu Takagi Yoichiro Matsumoto 《Microfluidics and nanofluidics》2017,21(2):15
The scattering dynamics of water molecules on solid surfaces was investigated using the molecular beam technique. In contrast to the experiments previously reported in the literature, the range of incident energy was chosen to cover the typical kinetic energies of gas molecules in equilibrium at room temperature (35–130 meV). Even in such a narrow energy range, the angular distribution of scattered molecules is heavily affected by the incident energy, exhibiting both a nearly cosine distribution and a lobular distribution, which has a clear peak close to the specular direction. Interestingly, the tangential momentum accommodation coefficients (TMACs) estimated from the scattering experiments show opposite energy dependences on graphite (0001) and silicon (100) surfaces. As the incident energy increases, the TMAC decreases on the graphite surface, whereas it increases on the silicon surface. These trends can be attributed to the relatively large adsorption energy of water molecules on these surfaces and the atomic-scale surface corrugation, although a rigorous understanding requires further analysis by molecular dynamics simulations. Our findings suggest the need for an elaborate slip-flow model that takes account of the incident energy effect to accurately analyze water vapor flow in micro/nanostructures, which is ubiquitous in nature and engineering applications. 相似文献
148.
Specific small amounts of amino acids caused agglomeration of L‐valine (L‐Val) crystals during evaporative crystallization from aqueous solutions. The agglomeration of L‐Val occurred only under acidic condition when guest amino acids satisfied several conditions. Only L‐form amino acids that have carboxylic acid groups and sufficiently long alkyl chain in the side‐chains could induce agglomeration of L‐Val. The length of alkyl chain in the side‐chains controls the degree of agglomeration. Data indicated only 0.5 wt % of L‐2‐aminoadipic acid, which has a similar chemical structure to L‐glutamic acid (L‐Glu), produced the large agglomerates > 1000 μm. The particle size was ~ 500 μm when using the same amount of L‐Glu. Based on the results from previous tests and this paper, the whole mechanism for the L‐Val agglomeration in the presence of specific guest amino acids has been revealed. 相似文献
149.
150.
Demands for higher rotational speed and accuracy for effective manufacture of small holes on printed circuit boards and very small precise parts have been increasing remarkably. Aerostatic journal bearings with compound restrictors have greater stiffness than those with conventional inherently compensated restrictors and are one of the most effective candidates to satisfy these demands. In this work, the instability of a rigid rotor supported by aerostatic journal bearings with compound restrictors was investigated numerically and experimentally. It was found that this type of aerostatic bearings showed a much higher threshold speed for instability compared with bearings with inherently compensated restrictors. 相似文献