全文获取类型
收费全文 | 211篇 |
免费 | 12篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 22篇 |
金属工艺 | 7篇 |
机械仪表 | 16篇 |
建筑科学 | 5篇 |
能源动力 | 1篇 |
轻工业 | 10篇 |
水利工程 | 1篇 |
无线电 | 61篇 |
一般工业技术 | 61篇 |
冶金工业 | 10篇 |
原子能技术 | 3篇 |
自动化技术 | 25篇 |
出版年
2023年 | 2篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 16篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有223条查询结果,搜索用时 296 毫秒
91.
Weakly Conjugated Hybrid Zinc Porphyrin Sensitizers for Solid‐State Dye‐Sensitized Solar Cells 下载免费PDF全文
Peng Qin Paek Sanghyun M. Ibrahim Dar Kasparas Rakstys Hany ElBatal Shaheen A. Al‐Muhtaseb Christian Ludwig Mohammad Khaja Nazeeruddin 《Advanced functional materials》2016,26(30):5550-5559
Molecularly engineered weakly conjugated hybrid porphyrin systems are presented as efficient sensitizers for solid‐state dye‐sensitized solar cells. By incorporating the quinolizino acridine and triazatruxene based unit as the secondary light‐harvester as well as electron‐donating group at the meso‐position of the porphyrin core, the power conversion efficiencies of 4.5% and 5.1% are demonstrated in the solid‐state devices containing 2,2′,7,7′‐tetrakis (N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spiro bifluorene as hole transporting material. The photovoltaic performance of the triazatruxene donor based porphyrin sensitizer is better than that of the previously published porphyrin molecules exhibiting strongly conjugated push–pull structure. The effect of molecular structure on the optical and electrochemical properties, the dynamics of charge extraction, as well as the photovoltaic performance are systematically investigated, which offers a new design strategy for further refinement of porphyrin molecules. 相似文献
92.
93.
Bung-Uk Yoo Seung-Hyun Kim Sung-Bin Park Sung-Jai Lee Jun-Hyuk Jang Seung-Woo Paek 《Journal of Nuclear Science and Technology》2016,53(12):2079-2089
To improve the uranium recovery rate in pyroprocessing, it is crucial to develop a planar-type electrorefiner. This can be achieved prior to actual experiments by using computer simulations to analyze the shape, arrangement, and size of the cathode. In this paper, tertiary-model-based computational analysis was performed on a planar-type electrorefiner. Flat-plate and rod-type cathodes were analyzed under constant-current condition; calculations were performed on high-efficiency-type electrodes with convection effects under the same conditions by comparing the dependence of the generated overpotential on the applied current. Analytic and experimental results were analyzed by comparing the electric potential of the plate-type device with that of a uranium electrorefiner while varying the arrangement of the electrodes. 相似文献
94.
The most promising applications for standing-wave thermoacoustic cooling were investigated from the perspective of the ratio of coefficient of performance (COP) to the reversible COP or COPR. A design optimization program based on the thermoacoustic simulation program known as DELTAE was developed. The program was applied to two standing-wave thermoacoustic cooler configurations in order to determine the best possible COPRs for various temperature spans between hot-side and cold-side stack-end temperatures. It was found that the COPR of standing-wave thermoacoustic coolers increases with temperature span and reaches a maximum for temperature lifts around 80 °C. Analysis of the results and the losses clearly shows that the efficiency of these systems may be good for refrigeration, but not for air-conditioning and cryogenic cooling. The COPRs determined from measurements for various thermoacoustic coolers developed so far show similar trends, and generally support the optimization results. 相似文献
95.
Kang JH Paek SM Choy YB Hwang SJ Choy JH 《Journal of nanoscience and nanotechnology》2007,7(11):4131-4134
Poly-(3,4-ethylenedioxythiophene) (PEDOT) is an ideal polymer for electrochromic (EC) devices due to its fast response time, high conductivity, and facile fabrication in a doped form except its demerit like an optical contrast limitation. In this study, we developed a simple way to overcome low coloration efficiency of PEDOT through fabricating a complementary PEDOT and prussian blue full cell system. Fundamental properties of EC displays, such as optical contrast, coloration efficiency, and switching speed, could be successfully optimized by controlling the deposition time and applied voltage during EDOT polymerization. In particular, UV transmittance spectra indicated that the optical contrast was enhanced up to 31 approximately 99% at the wavelength of 600 nm. Scanning electron microscopy images showed that the optimized PEDOT and prussian blue films were deposited on ITO glass substrate with an uniform thickness of approximately 180 nm and approximately 190 nm, respectively. Moreover, according to the circuit analysis, the average response time of electric current for the optimized full cell system was about 400 ms. It is, therefore, concluded that such a full cell system could have high potential applications as smart windows and/or optical devices. 相似文献
96.
Byungjin HwangYeong-Kyeun Paek Seung-Ho YangSunkwon Lim Won-Seon SeoKyung-Sik Oh 《Journal of Alloys and Compounds》2011,509(27):7478-7483
With the doping of Al in ZnO for the preparation of a bulk transparent conductor target, deteriorations were observed in sinterability and uniformity. The doping of 3 wt% Al resulted in the predominance of open pores after sintering at 1300 °C. Less open pores were observed in the ZnO with 2 wt% Al, but the porosity between the inner and outer regions was not uniform due to the preferential evaporation near the surface. To improve both the sinterability and uniformity, mild (<2 MPa) pressure was applied during the preliminary heat treatment at 900 °C, before pressureless final sintering. The pressed specimens showed increased density and uniformity after the final sintering, which were higher than those of the unpressed specimens. The improvements were particularly noticeable in the 3 wt% Al and at 1250 °C, wherein the conventional densification was not successful. 相似文献
97.
The phytohormone gibberellic acid (GA) has essential signaling functions in multiple processes during plant development. In the “Green Revolution”, breeders developed high-yield rice cultivars that exhibited both semi-dwarfism and altered GA responses, thus improving grain production. Most studies of GA have concentrated on germination and cell elongation, but GA also has a pivotal role in floral organ development, particularly in stamen/anther formation. In rice, GA signaling plays an important role in spikelet fertility; however, the molecular genetic and biochemical mechanisms of GA in male fertility remain largely unknown. Here, we review recent progress in understanding the network of GA signaling and its connection with spikelet fertility, which is tightly associated with grain productivity in cereal crops. 相似文献
98.
Motion estimation using multiple reference frames is widely used as the basis for recent video coding standards (eg. H.264/AVC)
to achieve increased coding efficiency. However, this increases the complexity of the encoding process. In this paper, a new
technique for efficient motion estimation is proposed. A combination of multiple reference frame selection and image residue-based
mode selection is used to improve motion estimation time. By dynamic selection of an initial reference frame in advance, the
number of reference frames to be considered is reduced. In addition, from examination of the residue between the current block
and reconstructed blocks in preceding frames, variable block size mode decisions are made. Modified initial motion vector
estimation and early stop condition detection are also adopted to speed up the motion estimation procedure. Experimental results
compare the performance of the proposed algorithm with a state of the art motion estimation algorithm and demonstrate significantly
reduced motion estimation time while maintaining PSNR performance. 相似文献
99.
Dong Hwa Kang Paek Hyoun Mo Dong Hee Choi Seung Yeong Song Myoung Souk Yeo Kwang Woo Kim 《Building and Environment》2010
This paper investigates the energy-saving potential of a thermal comfort-controlled office building. A comparative simulation study between the thermal comfort control and conventional thermostatic control is conducted on a building with glass façades where changes in the outdoor temperature and solar radiation over the course of a day affect radiant temperature and thus thermal comfort. To evaluate the thermal performance in the comfort-controlled space, a PMV-based thermal comfort controller, which adjusts the set-point room temperature of the existing thermostatic controller according to the changes of environmental variables, is assumed. The results demonstrate that thermal comfort competes with energy saving in a conventional thermostatic-controlled space. However, it is suggested that thermal comfort control provides consistent thermal comfort as well as energy-saving effect. The results show that energy consumption in a thermal comfort-controlled space is more affected by a change in the mean radiant temperature than in the conventional thermostatic-controlled space. The energy-saving potential in the thermal comfort-controlled space increases with low mean radiant temperature conditions. Although the energy-saving potential is reduced under high mean radiant temperature conditions, it is suggested that thermal comfort control is still a reasonable strategy to achieve both thermal comfort and energy savings simultaneously. 相似文献
100.
Sung-Nam Lee Ryu H.Y. Paek H.S. Son J.K. Sung Y.J. Kim K.S. Kim H.K. Kim H. Jang T. Ha K.H. Nam O.H. Park Y. 《Electron Device Letters, IEEE》2008,29(8):870-872
InGaN quantum-well (QW) green laser diodes (LDs) with an emission wavelength of 483.7 nm were characterized by controlling the injection pulsewidth. The emission wavelength of LDs showed a large blueshift (> 20 nm) of spontaneous emission peak with increasing injection current below the threshold current. The huge blueshift was ascribed to the deep In localization states and the strong piezoelectric field in the green InGaN QW structure with higher In contents than conventional violet/blue InGaN QWs. However, the lasing wavelength of LDs was slightly redshifted by increasing the injection pulsewidth due to the thermal heating effects. 相似文献