全文获取类型
收费全文 | 1166篇 |
免费 | 41篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 145篇 |
综合类 | 2篇 |
化学工业 | 315篇 |
金属工艺 | 40篇 |
机械仪表 | 42篇 |
建筑科学 | 22篇 |
矿业工程 | 3篇 |
能源动力 | 44篇 |
轻工业 | 126篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 60篇 |
一般工业技术 | 186篇 |
冶金工业 | 32篇 |
原子能技术 | 29篇 |
自动化技术 | 166篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 37篇 |
2020年 | 13篇 |
2019年 | 21篇 |
2018年 | 26篇 |
2017年 | 18篇 |
2016年 | 45篇 |
2015年 | 28篇 |
2014年 | 46篇 |
2013年 | 90篇 |
2012年 | 59篇 |
2011年 | 92篇 |
2010年 | 56篇 |
2009年 | 68篇 |
2008年 | 65篇 |
2007年 | 74篇 |
2006年 | 53篇 |
2005年 | 42篇 |
2004年 | 37篇 |
2003年 | 27篇 |
2002年 | 43篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 26篇 |
1997年 | 14篇 |
1996年 | 15篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有1216条查询结果,搜索用时 78 毫秒
111.
TAKETOSHI TAKEMURA MASAHIRO KOBAYASHI YOSHIO TAKADA KEN SATO 《Journal of the American Ceramic Society》1986,69(5):430-436
The nonlinearity of ZnO varistors is significantly influenced by the Bi2 O3 and Sb2 O3 contents, as well as by the phase composition of the Bi2 O3 . Degradation of the current-voltage characteristics due to the applied voltage is not always lowered by the β—γ transition of the Bi2 O3 phase. Lattice parameter determinations and stress analyses suggest that the Bi2 O3 -rich phase in multigrain junctions causes mechanical strain at the grain boundary which may play an important role in the current-voltage characteristics of ZnO varistors. 相似文献
112.
To develop a quantitative method for predicting shrinkage porosity in squeeze casting 总被引:1,自引:0,他引:1
In order to secure high strength and high elongation of suspension parts, it is critical to predict shrinkage porosity quantitatively. A new simulation method for quantitative predic'don of shrinkage porosity when replenishing molten metal has been proposed for squeeze casting process. To examine the accuracy of the calculation model, the proposed method was applied to a plate model. 相似文献
113.
Abstracts are not published in this journal 相似文献
114.
Some tetracycline (TC) antibiotics, including TC and anhydrotetracycline, have been found to enhance specific binding of low
density lipoprotein (LDL) to both LDL receptor-positive and-negative cells at relatively higher concentrations. When incubated
at 37°C, the ability of LDL receptor-negative human fibroblasts to bind 125I-LDL was increased from<2 to 45 ng/mg by 170 μM TC. In normal human fibroblasts and Hep G2 cells, 125I-LDL binding was elevated 1.4- to 2-fold by 113 μM TC. The 125I-LDL binding in the presence of TC was diminished by both heparin and EDTA. The enhancement by TC was not observed when 125I-LDL binding was assayed at 4°C. TC enhanced LDL binding to paraformaldehyde-fixed Hep G2 cells, excluding LDL receptor induction
in the mechanism. These results demonstrated that TC enhanced cellular LDL binding through a process not involving functional
LDL receptors. 相似文献
115.
Shinji Tsuneyuki Hikaru Kitamura Tadashi Ogitsu Takashi Miyake 《Journal of Low Temperature Physics》2001,122(3-4):291-296
Quantum distributions of protons in three high-pressure phases of solid molecular hydrogen are investigated by the first-principles path integral molecular dynamics (FP-PIMD) method, in which interatomic forces are calculated precisely based on the density functional theory. The distributions have entirely different symmetries from those predicted by conventional simulation with classical treatment of protons. Especially in phase II, we found that molecular rotation is hindered by quantum fluctuation of protons, having a strong resemblance to a quantum distribution of impurity muonium in crystalline silicon. The mechanism of this “quantum localization” is clarified by a detailed study of the potential energy surface for the molecular rotation. 相似文献
116.
This letter describes the successful fabrication of a 0.95Sn−0.05Au solder microbump on a compound semiconductor wafer by
reflowing of multi-layer metal film. Since the inherent interdiffusion in Au−Sn phases results in the alloying of multi-layer
films, the composition of micro-bump is well controlled by the thickness of constituent metal films. The micro-bumps melt
at about 220 C, which is close to the lowest eutectic temperature in a Au−Sn system. Solder bonding using 0.95Sn−0.05Au micro-bump
is a very useful technique for the flipchip bonding of compound semiconductor devices. 相似文献
117.
Study on dominant mechanism of high-cycle fatigue life in 6061-T6 aluminum alloy through microanalyses of microstructurally small cracks 总被引:1,自引:0,他引:1
Yoshimasa Takahashi Takahiro Shikama Shinji Yoshihara Tadashi Aiura Hiroshi Noguchi 《Acta Materialia》2012,60(6-7):2554-2567
The mechanism controlling the fatigue life of a precipitation-hardened Al–Mg–Si alloy (6061-T6) at a high-cycle fatigue (HCF) regime of over 107 cycles was investigated in detail. It was found that over 90% of the total fatigue life was occupied by the growth process of a microstructurally small crack at relatively low stress amplitude. The small crack was often found to be arrested and halted for a long period (more than 106 cycles) before it began to grow again, which resulted in a significantly slow growth process. The small crack was then analyzed not only by the conventional fractography but also by the cross-sectional observation of the crack tip region using a focused ion beam and transmission electron microscopy. These observations, supplemented also by a grain orientation analysis using electron backscattered diffraction, explicitly revealed the following points: (i) the small crack growth observed on the specimen surface is primarily related to facet-type cracking that occurs exclusively at the specimen surface; (ii) the growth direction of the small crack has strong anisotropy (i.e. surface-induced growth); (iii) the facet-type cracking is related to the formation of persistent fine slip bands that accompany no structural change of the matrix. On the basis of these results, the micromechanism of small crack growth and its relation to the concept of fatigue limit at the HCF regime is discussed in detail. 相似文献
118.
One of the most important technologies for electric vehicles (EVs) will be drive control technology for the main motor. It is desired that the drive control technology have the following characteristics. (1) It does not require a position/speed sensor for controlling motor drive, which has been mounted on the rotor shaft. (2) It has vector controls that can produce torque quickly, efficiently, and/or precisely. (3) It has wide driving‐range and allows developing EVs with no variable transmission. This paper proposes new drive control technologies for such EVs using a permanent‐magnet synchronous motor as a main motor, and verifies its usefulness through development of an actual EV that can drive on public roads. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 83–94, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20459 相似文献
119.
Raynoo Thanan Shinji Oikawa Yusuke Hiraku Shiho Ohnishi Ning Ma Somchai Pinlaor Puangrat Yongvanit Shosuke Kawanishi Mariko Murata 《International journal of molecular sciences》2015,16(1):193-217
Reactive oxygen and nitrogen species have been implicated in diverse pathophysiological conditions, including inflammation, neurodegenerative diseases and cancer. Accumulating evidence indicates that oxidative damage to biomolecules including lipids, proteins and DNA, contributes to these diseases. Previous studies suggest roles of lipid peroxidation and oxysterols in the development of neurodegenerative diseases and inflammation-related cancer. Our recent studies identifying and characterizing carbonylated proteins reveal oxidative damage to heat shock proteins in neurodegenerative disease models and inflammation-related cancer, suggesting dysfunction in their antioxidative properties. In neurodegenerative diseases, DNA damage may not only play a role in the induction of apoptosis, but also may inhibit cellular division via telomere shortening. Immunohistochemical analyses showed co-localization of oxidative/nitrative DNA lesions and stemness markers in the cells of inflammation-related cancers. Here, we review oxidative stress and its significant roles in neurodegenerative diseases and cancer. 相似文献
120.
Hiroaki Inoue Yuji Arai Tsunao Kishida Ryu Terauchi Kuniaki Honjo Shuji Nakagawa Shinji Tsuchida Tomohiro Matsuki Keiichirou Ueshima Hiroyoshi Fujiwara Osam Mazda Toshikazu Kubo 《International journal of molecular sciences》2015,16(1):1043-1050
Hypoxia-inducible factor (HIF)-2α is considered to play a major role in the progression of osteoarthritis. Recently, it was reported that pressure amplitude influences HIF-2α expression in murine endothelial cells. We examined whether hydrostatic pressure is involved in expression of HIF-2α in articular chondrocytes. Chondrocytes were cultured and stimulated by inflammation or hydrostatic pressure of 0, 5, 10, or 50 MPa. After stimulation, heat shock protein (HSP) 70, HIF-2α, nuclear factor kappa B (NF-κB), matrix metalloproteinase (MMP)-13, MMP-3, and vascular endothelial growth factor (VEGF) gene expression were evaluated. The levels of all gene expression were increased by inflammatory stress. When chondrocytes were exposed to a hydrostatic pressure of 5 MPa, HIF-2α, MMP-13, and MMP-3 gene expression increased significantly although those of HSP70 and NF-κB were not significantly different from the control group. In contrast, HIF-2α gene expression did not increase under a hydrostatic pressure of 50 MPa although HSP70 and NF-κB expression increased significantly compared to control. We considered that hydrostatic pressure of 5 MPa could regulate HIF-2α independent of NF-κB, because the level of HIF-2α gene expression increased significantly without upregulation of NF-κB expression at 5 MPa. Hydrostatic pressure may influence cartilage degeneration, inducing MMP-13 and MMP-3 expression through HIF-2α. 相似文献