全文获取类型
收费全文 | 2958篇 |
免费 | 116篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 218篇 |
综合类 | 10篇 |
化学工业 | 885篇 |
金属工艺 | 114篇 |
机械仪表 | 73篇 |
建筑科学 | 61篇 |
能源动力 | 160篇 |
轻工业 | 316篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 151篇 |
一般工业技术 | 653篇 |
冶金工业 | 125篇 |
原子能技术 | 79篇 |
自动化技术 | 237篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 38篇 |
2021年 | 54篇 |
2020年 | 34篇 |
2019年 | 47篇 |
2018年 | 57篇 |
2017年 | 51篇 |
2016年 | 62篇 |
2015年 | 53篇 |
2014年 | 103篇 |
2013年 | 236篇 |
2012年 | 140篇 |
2011年 | 221篇 |
2010年 | 166篇 |
2009年 | 178篇 |
2008年 | 186篇 |
2007年 | 157篇 |
2006年 | 141篇 |
2005年 | 133篇 |
2004年 | 118篇 |
2003年 | 107篇 |
2002年 | 101篇 |
2001年 | 69篇 |
2000年 | 55篇 |
1999年 | 45篇 |
1998年 | 39篇 |
1997年 | 46篇 |
1996年 | 38篇 |
1995年 | 34篇 |
1994年 | 53篇 |
1993年 | 34篇 |
1992年 | 29篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 21篇 |
1988年 | 21篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 11篇 |
1983年 | 23篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 6篇 |
排序方式: 共有3088条查询结果,搜索用时 15 毫秒
51.
A warpage index (Δψm) was introduced for studying warpage characteristics of a plastic part injection molded from PA66 compounded with 30 wt% glass fiber. Δψm is defined as Δψm = (Δψm)max – (Δψm)min, where ψm = ψ(θ)max, where ψ(θ) = (ε(θ) – α(θ)ΔT)/| α(θ)ΔT|, where ε is the total strain, α is the linear thermal expansion coefficient, ΔT is temperature difference, and θ is the angle along which ε and α are calculated. Finite element analysis was used for calculating flow field in injection, fiber orientation, material anisotropy and warpage. ψm is calculated in each finite element, and Δψm is calculated in a whole finite element model. Δψm is a measure of the ratio of actual shrinkage to the amount of shrinkage that would occur if an element freely shrank. The characteristics of Δψm were studied. It has been found that warpage is null if Δψm = 0, but that null warpage generally does not indicate Δψm = 0. It is shown that Δψm quantitatively represents the warped and unwarped state. Δψm distinguishes the null warpage state with possible buckling from the null warpage state without possible buckling. It has been shown that material anisotropy is possibly described with Δψm, and that the cause of warpage is self-restrictive deformation in an injection molded part. It has been deduced that it is generally not possible to eliminate warpage only by controlling material properties. Δψm is obtainable for a plastic part with complex geometry and complex fiber orientation state, and for arbitrary materials. Applications of Δψm are left for future study. 相似文献
52.
Shinji Miwa Norio Yamamoto Katsuhiro Hayashi Akihiko Takeuchi Kentaro Igarashi Hiroyuki Tsuchiya 《International journal of molecular sciences》2022,23(3)
Simple SummaryChondrosarcomas develop chemoresistance to standard anticancer drugs, making it difficult to control unresectable or metastatic chondrosarcomas. To improve the clinical outcomes of chondrosarcoma, new treatment approaches, such as molecule-targeting agents and immunotherapy, are needed. Recent research has revealed promising biomarkers and therapeutic targets for chondrosarcoma. In addition, several molecule-targeting agents have shown favorable antitumor activities in several clinical studies in patients with advanced sarcomas, including chondrosarcoma. This review summarizes recent basic studies on biomarkers and therapeutic targets and recent clinical studies on treating chondrosarcomas.AbstractDue to resistance to standard anticancer agents, it is difficult to control the disease progression in patients with metastatic or unresectable chondrosarcoma. Novel therapeutic approaches, such as molecule-targeting drugs and immunotherapy, are required to improve clinical outcomes in patients with advanced chondrosarcoma. Recent studies have suggested several promising biomarkers and therapeutic targets for chondrosarcoma, including IDH1/2 and COL2A1. Several molecule-targeting agents and immunotherapies have shown favorable antitumor activity in clinical studies in patients with advanced chondrosarcomas. This review summarizes recent basic studies on biomarkers and molecular targets and recent clinical studies on the treatment of chondrosarcomas. 相似文献
53.
Tohru Morii Toshio Tanimoto Hiroyuki Hamada Zen-Ichiro Maekawa Takahiro Hirano Kenji Kiyosumi 《Polymer Composites》1994,15(3):206-216
This study deals with the fracture process and acoustic emission (AE) characteristics of a randomly oriented E-glass fiber mat reinforcement with a crosslinked polyester. These panels were evaluated after they were immersed in hot water. The fiber volume content of the panel was 19%. Glass fiber reinforced plastics (GFRP) panels wer immersed in water at 81°C. Bending and AE monitoring tests were Performed and after bending, the cross-section of the specimen was observed by an optical microscope and SEM. The influence of degradation, due to water immersion, on the changes of fracture process of GFRP is discussed. The dominant fracture mode of the virgin specimen was matrix cracks, whereas that of the immersed specimen was debondings at the fiber bundle/matrix and fiber/matrix interfaces. This change was caused by reduction of the bonding strength at the interface. The scale of fracture can be estimated by both AE amplitude and AE energy and this estimation method was used to estimate the fracture mode changes of GFRP panels immersed in hot water. 相似文献
54.
Shoji Eita Takahashi Ryuji Isogai Shosei Ito Naoto Kubo Masaki Tsukada Takao Fukuyama Hiroyuki 《Metallurgical and Materials Transactions B》2019,50(5):2454-2458
Metallurgical and Materials Transactions B - Normal spectral emissivity of molten Cu-Fe alloy with different compositions was measured at the wavelength of 807 nm using an electromagnetic... 相似文献
55.
Li Minggang Matsuura Hiroyuki Tsukihashi Fumitaka 《Metallurgical and Materials Transactions B》2019,50(6):2993-3001
Metallurgical and Materials Transactions B - Evolution of TiS in composition and morphology as well as the change in size distribution of TiS and TiN in Fe-40 masspctNi austenitic alloy during... 相似文献
56.
Takanori Furuta Ichiro Nakagawa Shohei Yokoyama Yudai Morisaki Yasuhiko Saito Hiroyuki Nakase 《International journal of molecular sciences》2022,23(7)
Mitochondrial membrane potential regulation through the mitochondrial permeability transition pore (mPTP) is reportedly involved in the ischemic postconditioning (PostC) phenomenon. Melatonin is an endogenous hormone that regulates circadian rhythms. Its neuroprotective effects via mitochondrial melatonin receptors (MTs) have recently attracted attention. However, details of the neuroprotective mechanisms associated with PostC have not been clarified. Using hippocampal CA1 pyramidal cells from C57BL mice, we studied the involvement of MTs and the mPTP in melatonin-induced PostC mechanisms similar to those of ischemic PostC. We measured changes in spontaneous excitatory postsynaptic currents (sEPSCs), intracellular calcium concentration, mitochondrial membrane potential, and N-methyl-D-aspartate receptor (NMDAR) currents after ischemic challenge, using the whole-cell patch-clamp technique. Melatonin significantly suppressed increases in sEPSCs and intracellular calcium concentrations. The NMDAR currents were significantly suppressed by melatonin and the MT agonist, ramelteon. However, this suppressive effect was abolished by the mPTP inhibitor, cyclosporine A, and the MT antagonist, luzindole. Furthermore, both melatonin and ramelteon potentiated depolarization of mitochondrial membrane potentials, and luzindole suppressed depolarization of mitochondrial membrane potentials. This study suggests that melatonin-induced PostC via MTs suppressed the NMDAR that was induced by partial depolarization of mitochondrial membrane potential by opening the mPTP, reducing excessive release of glutamate and inducing neuroprotection against ischemia-reperfusion injury. 相似文献
57.
Yusuke Furuta Hiroyuki Nishikawa Takahiro Satoh Yasuyuki Ishii Tomihiro Kamiya Ryota Nakao Satoshi Uchida 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(12-13):2285-2288
Fabrication of high-aspect-ratio microstructures was performed by proton beam writing (PBW) using a microbeam line at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA), JAEA Takasaki, JAPAN. As one of the applications of the high-aspect-ratio structures micro-machined by PBW, we utilized the high-aspect pillars for electric-micro filters of microbes such as Escherichia coli and Yeast based on the dielectrophoretic force. The filter is equipped with high-aspect pillars with a height of ~20 μm and a diameter of ~1 μm on a glass plate. Evaluation of the dielectrophoresis (DEP) device for capturing E. coli and Yeast was made using either observation by optical microscope or photoluminescence (PL) measurements. 相似文献
58.
Shinji Fukuda Kazuhiko Shimada Noriya Izu Hiroyuki Miyazaki Shoji Iwakiri Kiyoshi Hirao 《Journal of Materials Science: Materials in Electronics》2018,29(14):11688-11698
We observed crack generation and structural changes in electroless nickel–phosphorus (Ni–P) plating layers formed on copper-metalized silicon nitride substrates both during thermal cycling from ? 40 to 250 °C and during storage (not cycling) at 250 °C in order to investigate the effect of the phosphorus contents on crack generation and growth in the Ni–P platings. The used platings contained phosphorus at three different contents: 2.1 wt% [Ni–P(low)], 6.5 wt% [Ni–P(med)], and 10.9 wt% [Ni–P(high)]. The generation time and the amount of cracks were strongly dependent on their phosphorus contents. More cracks appeared after thermal cycling than after storage at 250 °C. In Ni–P(low), cracks were generated after 200 thermal cycles, whereas no cracks were observed even after 250 h of storage at 250 °C. In Ni–P(med) and Ni–P(high), both during thermal cycling and storage at 250 °C, cracks formed during or after crystallization of the amorphous layers. These results suggest that the primary factors affecting the generation of cracks in electroless Ni–P platings are crystallization of the Ni–P platings and repeated changes in thermal stress. 相似文献
59.
60.
Mitsuo Tosaki Hiroyuki Itoh Yasuhito Isozumi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(11-12):1749-1753
In order to evaluate stopping cross-section and energy straggling of protons in compound material SiC and its constituents C and Si, resonant backscattering spectra have been measured using proton beams in an energy range 4.9–6.1 MeV per a 100 keV step. We have observed two sharp nuclear resonances at proton energies of 4.808 MeV by 12C and 4.879 MeV by 28Si. By systematic analyses of the resonance peak profiles, i.e., energy shift of the peak position and broadening of the peak width, the values of the stopping cross-section and the energy straggling have been deduced to be compared with SRIM-2006 and Bohr’s prediction. 相似文献