全文获取类型
收费全文 | 600篇 |
免费 | 30篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 40篇 |
综合类 | 3篇 |
化学工业 | 180篇 |
金属工艺 | 21篇 |
机械仪表 | 11篇 |
建筑科学 | 7篇 |
能源动力 | 23篇 |
轻工业 | 40篇 |
水利工程 | 5篇 |
无线电 | 41篇 |
一般工业技术 | 138篇 |
冶金工业 | 34篇 |
原子能技术 | 38篇 |
自动化技术 | 53篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 40篇 |
2012年 | 36篇 |
2011年 | 73篇 |
2010年 | 35篇 |
2009年 | 40篇 |
2008年 | 34篇 |
2007年 | 32篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 17篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
排序方式: 共有634条查询结果,搜索用时 15 毫秒
41.
42.
Yugo Tadano Shota Urushibata Kazuya Ogura Akira Shigaki Masakatsu Nomura 《Electrical Engineering in Japan》2008,165(2):77-88
Recently, high‐voltage motor direct drive systems have been put to practical use, and various multilevel PWM strategies have also been proposed. This paper describes a multilevel PWM strategy [our group calls it the Carrier Phase Selection Method (CPS)] that has the lowest line voltage harmonic distortion in order to prevent the degradation of high‐voltage motor winding insulations. This method takes the adverse effect of dead time into consideration, and it controls the shift direction of a carrier phase. Therefore, a favorable output waveform without instantaneous voltage surges is achieved even if the line voltage level changes. Moreover, the switching transitions across all switching devices are well‐balanced, so the utilization of inverter unit cells is equalized. This is an important factor when designing the entire system. Based on simulation and experimental results, it is shown that this CPS method is particularly effective in high‐voltage motor direct drive systems. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 77–88, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20474 相似文献
43.
A Suminoe A Matsuzaki N Kinukawa T Inamitsu T Tajiri S Suita T Hara 《Canadian Metallurgical Quarterly》1999,134(2):178-184
OBJECTIVE: To evaluate the association of somatic growth from birth through diagnosis with the development of childhood cancer. METHODS: The weights and heights of 1718 children with cancers were determined and converted into standard deviation (SD) scores, both at birth and at diagnosis, by using the means and SD values of the general population. RESULTS: Among patients with neuroblastoma and acute lymphoblastic leukemia, the percentages of children with body weight and height over mean + 2 SDs were significantly higher at diagnosis than the expected value in the general population. The percentage of children with neuroblastoma and body weight over mean + 2 SD increased significantly from birth through diagnosis (P =.04). Although the medians of weight SD scores decreased from birth through diagnosis in patients with representative cancers except for neuroblastoma, the value significantly increased in patients with neuroblastoma diagnosed before 1 year of age (P =.03), especially in those whose cancer was detected by mass screening at 6 months of age (P <.01). CONCLUSIONS: Rapid somatic growth from birth through diagnosis in patients with neuroblastoma diagnosed before 1 year of age suggests a possible involvement of certain growth factors in these patients. 相似文献
44.
Kazuya Tsujino 《Electrochimica acta》2007,53(1):28-34
Holes with diameters of tens of nanometers were bored in Si(1 0 0) in aqueous solutions containing hydrofluoric acid and hydrogen peroxide utilizing silver nanoparticles as catalysts. The holes grew deeply in the [1 0 0] direction when the concentration of hydrogen peroxide was about 0.18 M. In addition to these vertical holes, holes were generated horizontal to the surface in the 〈1 0 0〉 directions near the surface of the sample. We found that the silver particles making the deep holes in the [1 0 0] direction were more spherical than those making the horizontal holes near the surface. These results indicate that the shape of the silver particles is an important factor controlling the direction of the holes. When the hydrogen peroxide concentration was increased to 1.8 M, as well as the vertical and horizontal holes, a microporous layer was formed on the top surface region. On the other hand, when the hydrogen peroxide concentration was lowered to 0.0018 M, holes did not show any preference for growing direction and were crooked. Even in HF solutions that did not contain hydrogen peroxide, holes were generated at a very slow rate in random directions if the solutions contained oxygen. 相似文献
45.
46.
The aim of this paper is to investigate the influence of multi-valency of americium in its oxide for the lowering of the thermal conductivity and the uncertainty in measurement. In the present study, thermal conductivity of non-stoichiometric americium oxide was evaluated up to 2000 K by the non-equilibrium molecular dynamics calculations using the Born-Mayer-Huggins interatomic potential with the partially ionic model. The oxygen-to-americium ratio (O/Am) was varied from 1.6 to 1.9, which corresponded to the variation of the ratio of Am3+/Am4+. So, we prepared potential parameters for both Am3+ and Am4+. The calculated thermal conductivity of non-stoichiometric americium oxide decreased with an increase of temperature, and the degree of the temperature dependence became smaller with a decrease of the O/Am ratio. This was mainly caused by the phonon-scattering due to oxygen vacancies induced with Am3+ ions. Comparing two supercells in which (1) short-range ordered Am3+ clusters were contained and (2) Am3+ ions were randomly distributed, the thermal conductivity of the former seemed to be somewhat larger than that of the latter. 相似文献
47.
Kazuya Sasaki Takayuki Terai Akihiro Suzuki 《International Journal of Applied Ceramic Technology》2009,6(3):362-372
The microstructure of a thermal shielding material affects its thermal conductivity and mechanical property. In this study, the effects of the sintering temperature and the polymethyl methacrylate powder as a pore-former on the microstructure of a sintered porous yttria-stabilized zirconia (YSZ), which is used as a durable thermal shielding material, were investigated. It became clear that the microstructure of the sintered YSZ could be controlled by the particle size and the amount of the pore-former and the sintering temperature. The effect of the yttria amount in the YSZ on the microstructure was also clarified. 相似文献
48.
Hidetaka Kawakita Hiroyasu Masunaga Kanako Nomura Kazuya Uezu Isamu Akiba Satoshi Tsuneda 《Journal of Porous Materials》2007,14(4):387-391
Protein adsorption was performed by a polymer brush prepared by atom-transfer radical polymerization (ATRP) to a porous inorganic
membrane. The porous inorganic membrane, Shirasu Porous Glass made from silica, was modified with a halogen-containing compound
to bind the active species for the polymerization. Glycidyl methacrylate was polymerized from the halogen compound by ATRP
for a prescribed time, and subsequently chemically modified. The progression of the chemical modification allowed the membrane
to lower the phosphate-buffer flux of the porous membrane due to the attachment of the polymer brush. Bovine serum albumin
(BSA), as a model protein, was adsorbed at 12 mg per gram of the membrane in permeating BSA solution through the polymer-brush-attached
porous membrane. 相似文献
49.
以溶胶—凝胶法(sol-gel)为基础,乙醇作溶剂,在氨水催化作用下,研究了正硅酸乙酯(TEOS)通过水解聚合反应制备Si O2微球的方法,并探讨n(水)/n(TEOS)(简称H)及反应时间等因素的影响。本实验借助激光散射粒度分布分析仪研究Si O2微球在溶液态的分布情况,同时使用SEM对烘烤干燥后的Si O2微球进行表征,该方法制得的纳米Si O2微球分布集中,平均粒径在90 nm左右。 相似文献
50.
Kazuya Shimoda Tatsuya Hinoki 《International Journal of Applied Ceramic Technology》2023,20(4):2466-2477
BN-nanoparticle-containing SiC-matrix-based composites comprising SiC fibers and lacking a fiber/matrix interface (SiC/BN + SiC composites) were fabricated by spark plasma sintering (SPS) at 1800°C for 10 min under 50 MPa in Ar. The content of added BN nanoparticles was varied from 0 to 50 vol.%. The mechanical properties of the SiC/BN + SiC composites were investigated thoroughly. The SiC/BN + SiC composites with a BN nanoparticle content of 50 vol.%, which had a bulk density of 2.73 g/cm3 and an open porosity of 5.8%, exhibited quasiductile fracture behavior, as indicated by a short nonlinear region and significantly shorter fiber pullouts owing to the relatively high modulus. The composites also exhibited high strength as well as bending, proportional limit stress, and ultimate tensile strength values of 496 ± 13, 251 ± 30, and 301 MPa ± 56 MPa, respectively, under ambient conditions. The SiC fibers with contents of BN nanoparticles above 30 vol.% were not severely damaged during SPS and adhered to the matrix to form a relatively weak fiber/matrix interface. 相似文献