全文获取类型
收费全文 | 872篇 |
免费 | 12篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 171篇 |
金属工艺 | 19篇 |
机械仪表 | 16篇 |
建筑科学 | 10篇 |
能源动力 | 37篇 |
轻工业 | 53篇 |
石油天然气 | 1篇 |
无线电 | 71篇 |
一般工业技术 | 151篇 |
冶金工业 | 264篇 |
原子能技术 | 25篇 |
自动化技术 | 50篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 27篇 |
2012年 | 38篇 |
2011年 | 66篇 |
2010年 | 33篇 |
2009年 | 18篇 |
2008年 | 33篇 |
2007年 | 31篇 |
2006年 | 25篇 |
2005年 | 21篇 |
2004年 | 29篇 |
2003年 | 16篇 |
2002年 | 24篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 20篇 |
1998年 | 116篇 |
1997年 | 65篇 |
1996年 | 41篇 |
1995年 | 25篇 |
1994年 | 24篇 |
1993年 | 18篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有884条查询结果,搜索用时 15 毫秒
101.
Ming-Jen Pan Seung-Eek Park Colin W. Park Kelley A. Markowski Shoko Yoshikawa Clive A. Randall 《Journal of the American Ceramic Society》1996,79(11):2971-2974
Under ferroelectric switching in Pb(Zr2 Ti)O3 (PZT) ceramics, we demonstrate that oxygen gas is emitted and degrades electrode microstructure. The oxygen is a direct result of the defect chemistry associated with superoxidation which is established during the processing of the ceramics. Under high alternating electric fields, electron injection into the ceramic surface induces a reduction process, and surface layers are believed to change from a p-type electronic compensation to an ionic compensation of oxygen vacancies and A-site lead vacancies. During this process, we noticed progressive changes in capacitance, loss, remnant polarization, and coercive field. The wider implications of this observation for PZT thin film nonvolatile memories are discussed in brief. 相似文献
102.
Kosaka H. Kurihara K. Uemura A. Yoshikawa T. Ogura I. Numai T. Sugimoto M. Kasahara K. 《Photonics Technology Letters, IEEE》1994,6(3):323-325
Vertical-to-surface transmission electrophotonic devices with a vertical-cavity are described. The individually accessed 12×4 arrays are characterized and demonstrated to have uniform room-temperature continuous-wave operating characteristics for a threshold current of ~2.8±0.15 mA and a slope efficiency of ~0.18±0.012 W/A with a single transverse mode. Both low threshold and high efficiency with 5% and 7% deviation, respectively, are achieved simultaneously. These devices can be used to constructing two-dimensional massively parallel optical interconnections 相似文献
103.
The effect of catechol on coal hydrogenolysis was studied using tetralin as a solvent vehicle. A constant high liquefaction yield was observed when the amount of catechol added was reduced from 10 to 0.1 % based on the weight of coal. Under the same hydrogenolysis conditions, identical conversion yields were observed even when no catechol was added. Separate experiments were carried out, using a new internal vessel and the original stirrer, to examine the effect of the stirrer on liquefaction yield. Improved liquefaction yields were achieved in these experiments (an increase from 31 to 64% at 400 °C and from 46 to 78% at 420 °C for Miike coal; from 26 to 48% at 400 °C and from 36 to 73% at 420 °C for Wandowan coal; and from 16 to 34% at 400 °C and 21 to 55% at 420 °C for Lithgow coal). This suggests that an active catalytic species is formed on the surface of the stirrer and the internal surface of the autocalve. 相似文献
104.
This report describes a method of determining irradiation effectiveness of different neutron spectra in causing radiation effects to fuel cladding and reactor structural materials. It involves the definition of a semi-empirical damage function or cross section using measured data from specimens irradiated in thermal and fast test reactor spectra. The damage function is applied to design problems involving irradiation effects to reactor structural and fuel cladding materials to predict the fluence which would produce a specific change in material properties. 相似文献
105.
106.
Supachai Ngamsinlapasathian Sorapong Pavasupree Yoshikazu Suzuki Susumu Yoshikawa 《Solar Energy Materials & Solar Cells》2006,90(18-19):3187-3192
Nanocrystalline mesoporous titania was obtained by surfactant-assisted templating method using tetraisopropyl orthotitanate modified with acethylacetone and laurylamine hydrochloride as template. This material was applied for the electrode of dye-sensitized solar cell. The mesoporous TiO2 (MP-TiO2) cells exhibited higher short-circuit photocurrent density and solar energy conversion efficiency compared to P25 (a typical commercial titania powder) cells. The incident photon to current conversion efficiency spectrum of MP-TiO2 can be improved by using the cell made with 5% P25 additive. Double-layer titania cells were fabricated to further improve cell performance by increasing the film thickness and light scattering. The solar conversion efficiency up to 8.06% was obtained by using the double-layer titania cell sintered at 450 °C for 2 h. 相似文献
107.
Tomita N. Ohtsuka N. Miyamoto J. Imamiya K. Iyama Y. Mori S. Ohsima Y. Arai N. Kaneko Y. Sakagami E. Yoshikawa K. Tanaka S. 《Solid-State Circuits, IEEE Journal of》1991,26(11):1593-1599
To meet the increasing demand for higher-density and faster EPROMs, a 16-Mb CMOS EPROM has been developed based on 0.6-μm N-well CMOS technology. In scaled EPROMs, it is important to guarantee device reliability under high-voltage operation during programming. By employing internal programming-voltage reduction and new stress relaxation circuits, it is possible to keep an external programming voltage V pp of 12.5 V. The device achieves a 62-ns access time with a 12-mA operating current. A sense-line equalization and data-out latching scheme, made possible by address transition detection (ATD), and a bit-line bias circuit with two types of depletion load led to the fast access time with high noise immunity. This 16-Mb EPROM has pin compatibility with a standard 16-Mb mask-programmable ROM (MROM) and is operative in either word-wide or byte-wide READ mode. Cell size and chip size are 2.2 μm×1.75 μm and 7.18 mm×17.39 mm, respectively 相似文献
108.
To succeed in the graphics controllers market, it is important to take advantage of embedded DRAMs, which provide low power consumption, low electromagnetic interference (EMI), smaller board space, and frame memory flexibility (capacity, access speed, and bandwidth). These capabilities benefit portable PC applications in which board space and power consumption are serious considerations. The MSM7680 accelerator is ideally suited for a compact multimedia system because of its smaller, embedded DRAM capacity. The MSM7680 provides high performance and/or a one-chip solution for many graphics display systems. It also integrates the frame buffer with graphics controller functions such as a 2D drawing engine, MPEG-1 decoder, digital/analog converter for RGB analog output, and a clock generator phase-locked loop. The MSM7680 multimedia accelerator uses a 256-bit data bus with embedded 1.25-Mbyte DRAM to increase the rate of data transfers and decrease power consumption 相似文献
109.
110.
K Hosokawa S Yoshitatsu M Kakibuchi S Nishimoto M Higashiyama K Yoshikawa 《Canadian Metallurgical Quarterly》1998,102(2):448-449
We report a case of identical twins with recessive dystrophic epidermolysis bullosa, who developed squamous cell carcinoma in the hand at the latter half of their third decade. To our knowledge, this is the first case of manifestation of squamous cell carcinoma in identical twins and may contribute to the understanding of oncogenesis in such patients. 相似文献