全文获取类型
收费全文 | 1388篇 |
免费 | 39篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 77篇 |
综合类 | 4篇 |
化学工业 | 302篇 |
金属工艺 | 46篇 |
机械仪表 | 29篇 |
建筑科学 | 19篇 |
能源动力 | 62篇 |
轻工业 | 76篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 131篇 |
一般工业技术 | 273篇 |
冶金工业 | 239篇 |
原子能技术 | 45篇 |
自动化技术 | 124篇 |
出版年
2023年 | 14篇 |
2022年 | 19篇 |
2021年 | 32篇 |
2020年 | 11篇 |
2019年 | 22篇 |
2018年 | 17篇 |
2017年 | 26篇 |
2016年 | 33篇 |
2015年 | 21篇 |
2014年 | 41篇 |
2013年 | 62篇 |
2012年 | 52篇 |
2011年 | 88篇 |
2010年 | 71篇 |
2009年 | 56篇 |
2008年 | 67篇 |
2007年 | 63篇 |
2006年 | 40篇 |
2005年 | 48篇 |
2004年 | 44篇 |
2003年 | 55篇 |
2002年 | 41篇 |
2001年 | 22篇 |
2000年 | 17篇 |
1999年 | 29篇 |
1998年 | 87篇 |
1997年 | 55篇 |
1996年 | 50篇 |
1995年 | 32篇 |
1994年 | 33篇 |
1993年 | 23篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 7篇 |
排序方式: 共有1432条查询结果,搜索用时 0 毫秒
71.
Takafumi Koike Kei Utsugi Michio Oikawa 《Journal of the Society for Information Display》2010,18(9):678-685
Abstract— Moiré‐reduction methods for integral videography displays are proposed. Integral videography is based on the principles of integral photography and extended real‐time video processing. There are two moiré‐reduction methods that can be used for integral videography displays that have a lens array and a liquid‐crystal display. The first is color moiré, and the second is intensity moiré. To reduce color moiré, an optimized color‐filter layout in the liquid‐crystal display was used. To reduce intensity moiré, a defocusing method was used. Adesign of a viewing area for the integral videography display is also presented. To control the viewing area, the lens pitch and the shape of the integral videography elemental image was changed. A 5‐in. integral videography display was implemented by using the proposed methods, and an integral videography display was evaluated. 相似文献
72.
Control of the Metal–Insulator Transition at Complex Oxide Heterointerfaces through Visible Light 下载免费PDF全文
73.
74.
Reo Etani Takahiro Kataoka Yuichi Nishiyama Yuji Takata 《Journal of Nuclear Science and Technology》2013,50(12):1512-1518
It has been reported that radon inhalation activates antioxidative functions in liver and has an antioxidative effect against hepatopathy similar to that of the antioxidative effects of ascorbic acid (VC) or α-tocopherol (VE). In this study, we examined the combined effects of radon inhalation and antioxidant vitamin administration on acute alcohol-induced hepatopathy in mice. ICR mice were subjected to intraperitoneal (i.p.) administration of alcohol after pretreating with air only (sham) or radon at a concentration of approximately 2000 Bq/m3 for 24 hours and i.p. administration of VC (300 mg/kg body weight) or VE (300 mg/kg body weight). In mice injected with alcohol, the combined radon and antioxidant vitamins treatment significantly decreased the activities of glutamic oxaloacetic transaminase in serum compared to not only the alcohol-administered group (sham group), but also the radon inhalation with alcohol administration group or the vitamin and alcohol administration group. In addition, radon inhalation significantly increased the antioxidant level, in such as the catalase activity and the total glutathione content in liver compared to the sham group. These results suggested that the combined radon and antioxidant vitamin treatment could effectively inhibit alcohol-induced hepatopathy in mice without any antagonizing action. 相似文献
75.
Uota M Hayashi Y Ohyama K Takemoto H Iriki R Kishishita T Shimoda M Yoshimura T Kawasaki H Sakai G Kijima T 《Journal of nanoscience and nanotechnology》2010,10(9):5790-5795
Platinum/carbon (Pt/C) composite materials were prepared by the hydrazine reduction of H2PtCl6 confined to a mixed surfactant lytropic liquid crystal (LC)/C mixture with varying amounts of water. The reaction at relatively low water contents successfully yielded cross-linked Pt nanowires with wire-widths of 2-5 nm. The novel Pt nanostructure is believed to be from poorly hydrated hexagonal domains formed together with layered domains by the phase separation of the precursory LC mixture in the presence of carbon. Electrochemical measurements using cyclic volutammetry and membrane electrode assemblies revealed that the cross-linked nanowired Pt/C composite exhibits fairly high electrocatalytic activity for oxygen reduction reaction, as well as a high performance as the cathode material for polymer electrolyte fuel cells. 相似文献
76.
H Asou M Koike E Elstner M Cambell J Le MR Uskokovic N Kamada HP Koeffler 《Canadian Metallurgical Quarterly》1998,92(7):2441-2449
We have studied the in vitro biological activities and mechanisms of action of 1,25-dihydroxyvitamin D3 (1,25D3) and nine potent 1,25D3 analogs on proliferation and differentiation of myeloid leukemia cell lines (HL-60, retinoic acid-resistant HL-60 [RA-res HL-60], NB4 and Kasumi-1). The common novel structural motiff for almost all the analogs included removal of C-19 (19-nor); each also had unsaturation of the side chain. All the compounds were potent; for example, the concentration of analogs producing a 50% clonal inhibition (ED50) ranged between 1 x 10(-9) to 4 x 10(-11) mol/L when using the HL-60 cell line. The most active compound [1, 25(OH)2-16,23E-diene-26-trifluoro-19-nor-cholecalciferol (Ro 25-9716)] had an ED50 of 4 x 10(-11) mol/L; in contrast, the 1,25D3 produced an ED50 of 10(-9) mol/L with the HL-60 target cells. Ro 25-9716 (10(-9) mol/L, 3 days) was a strong inducer of myeloid differentiation because it caused 92% of the HL-60 cells to express CD11b and 75% of these cells to reduce nitroblue tetrazolium (NBT). This compound (10(-8) mol/L, 4 days) also caused HL-60 cells to arrest in the G1 phase of the cell cycle (88% cells in G1 v 48% of the untreated control cells). The p27(kip-1), a cyclin-dependent kinase inhibitor which is important in blocking the cell cycle, was induced more quickly and potently by Ro 25-9716 (10(-7) mol/L, 0 to 5 days) than by 1,25D3, suggesting a possible mechanism by which these analogs inhibit proliferation of leukemic growth. The NB4 promyelocytic leukemia cells cultured with the Ro 25-9716 were also inhibited in their clonal proliferation (ED50, 5 x 10(-11) mol/L) and their expression of CD11b was enhanced (80% positive [10(-9) mol/L, 4 days] v 27% untreated NB4 cells). Moreover, the combination of Ro 25-9716 (10(-9) mol/L) and all-trans retinoic acid (ATRA, 10(-7) mol/L) induced 92% of the NB4 cells to reduce NBT, whereas only 26% of the cells became NBT positive after a similar exposure to the combination of 1,25D3 and ATRA. Surprisingly, Ro 25-9716 also inhibited the clonal growth of poorly differentiated leukemia cell lines (RA-res HL-60 [ED50, 4 x 10(-9) mol/L] and Kasumi-1 [ED50, 5 x 10(-10) mol/L]). For HL-60 cells, Ro 25-9716 markedly decreased the percent of the cells in S phase of the cell cycle and increased the expression of the cyclin-dependent kinase inhibitor, p27(kip-1). In summary, 19-nor vitamin D3 compounds strongly induced differentiation and inhibited clonal proliferation of various myeloid leukemia cell lines, suggesting a therapeutic niche for their use in myeloid leukemia. 相似文献
77.
Yuichi Miura Kazuo Mori Takayoshi Mamiya Tetsumasa Nakayasu 《Journal of Low Temperature Physics》1998,113(5-6):757-762
We have measured the dissipation of dislocation motion in bcc solid
3
He using the high-Q torsional oscillator technique at 1079 Hz. We observed a broad maximum in the temperature dependence of the dissipation. The maximum of the dissipation can be explained by the theory of Granato and Lucke in which the dislocation mobility depends upon the interactions of dislocations with point defects.
4
He impurities tend to bind to the dislocation lines at low temperatures and pin this dislocation motion. The maximum of the dissipation corresponds to the depinning of the dislocation motion. From the amplitude dependence of the depinning temperature we first obtained the activation energy of 1.03 K of the impurity
4
He atom trapped on the dislocations in bcc solid
3
He at a molar volume of 24.30 cm
3
/mol. The activation energy of the impurity atom in bcc
3
He was found to be larger than the value of 0.7 Kin hcp
4
He. 相似文献
78.
Photosensitivity in a perfluoropolymer (CYTOP) optical fibre is investigated. Significant diffraction has been observed from transmission gratings made from the fibre. A maximum diffraction efficiency of 1.6% has been achieved, corresponding to an index change ≃3×10-4. The study demonstrates for the first time the existence of significant photosensitivity and the feasibility of writing a Bragg grating in a CYTOP fibre 相似文献
79.
T Koike G Ishida M Taniguchi K Higaki Y Ayaki M Saito Y Sakakihara M Iwamori K Ohno 《Canadian Metallurgical Quarterly》1998,1406(3):327-335
We have investigated transformation with heterologous DNA as a method for insertional mutagenesis of Aspergillus fumigatus. Two methods, polyethylene glycol-mediated transformation of protoplasts and electroporation of germinating spores, were used to establish conditions leading to single-copy integration of transforming DNA at different genomic sites. We have assessed the effect of restriction enzyme-mediated integration (REMI) for both methods. Non-REMI protoplast transformation led to integration of multiple copies of transforming DNA in the majority of transformants. Results of REMI with protoplast transformation varied depending on the enzyme used. Low concentrations of several restriction enzymes stimulated transformation, but of ten enzymes investigated only REMI with XhoI and KpnI resulted in single-copy integration of transforming DNA for the majority of transformants. For protoplast transformation with XhoI- or KpnI-based REMI, 50% and 76% of insertions, respectively, were due to integrations at a genomic enzyme site corresponding to the enzyme used for REMI. Electroporation of spores without addition of restriction enzyme resulted in a high transformation efficiency, with up to 67% of transformants containing a single copy of transforming DNA. In contrast to protoplast transformation, electroporation of spores in the presence of a restriction enzyme did not improve transformation efficiency or lead to insertion at genomic restriction sites. Southern analysis indicated that for both protoplast transformation with REMI using KpnI or XhoI and for electroporation of spores without addition of restriction enzymes, transforming DNA inserted at different genomic sites in a high proportion of transformants. 相似文献
80.
Structural Distortion and Compositional Gradients Adjacent to Epitaxial LiMn2O4 Thin Film Interfaces
Xiang Gao Yumi H. Ikuhara Craig A. J. Fisher Hiroki Moriwake Akihide Kuwabara Hideki Oki Keiichi Kohama Ryuji Yoshida Rong Huang Yuichi Ikuhara 《Advanced Materials Interfaces》2014,1(8)
Thin film electrode materials are key components in the development of high rate, high capacity solid‐state Li‐ion batteries. Detailed knowledge of the epitaxial film/substrate(current‐collector) interface structures, which provides insights into epitaxial growth mechanisms and the effects of microstructure on electrochemical properties, is essential for efficient materials and device design. Here we report the epitaxial growth mechanism of a typical cathodic LiMn2O4 thin film by exploring the detailed structural and compositional variations in the vicinity of a film/substrate interface using state‐of‐the‐art scanning transmission electron microscopy. Direct observation of atom columns shows the epitaxial film forms an atomically flat and coherent heterointerface with the substrate, but that the crystal lattice is tetragonally distorted with a measurable compositional gradient from the interface to the crystal bulk. The growth mechanism is interpreted in terms of a combination of chemical and physicomechanical effects, namely a complex interplay between the internal Jahn‐Teller distortions induced by oxygen non‐stoichiometry and the lattice misfit strain. 相似文献