全文获取类型
收费全文 | 505篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 48篇 |
综合类 | 2篇 |
化学工业 | 170篇 |
金属工艺 | 12篇 |
机械仪表 | 27篇 |
建筑科学 | 12篇 |
能源动力 | 15篇 |
轻工业 | 35篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 39篇 |
一般工业技术 | 78篇 |
冶金工业 | 24篇 |
原子能技术 | 18篇 |
自动化技术 | 44篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 18篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 19篇 |
2013年 | 36篇 |
2012年 | 21篇 |
2011年 | 39篇 |
2010年 | 21篇 |
2009年 | 14篇 |
2008年 | 25篇 |
2007年 | 16篇 |
2006年 | 13篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 17篇 |
2002年 | 16篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1989年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1969年 | 3篇 |
排序方式: 共有526条查询结果,搜索用时 78 毫秒
101.
GaN surface stoichiometry and growth kinetics in MOVPE were studied by in-situ spectroscopic ellipsometry. The effect of MOVPE
conditions on both the surface stoichiometry and growth kinetics was investigated. The surface stoichiometry, such as N-rich,
Ga-rich and Ga-excess surfaces, was monitored, and was drastically changed by the variation of the NH3 partial pressure. When the TMG supply was interrupted during the growth, the layer-by-layer decomposition/revaporation was
observed in H2/NH3 ambient. The decomposition rate was measured as a function of the NH3 flow rate at the conventional epilayer growth temperatures (1050–1140 C). The decomposition rate was decreased with the increase
in the N coverage on the GaN surface. it was found that the surface stoichiometry is a very important parameter for the control
of the MOVPE growth kinetics. 相似文献
102.
Five kinds of PEEK/CF composites, made by blending poly-ether-ether-ketone (PEEK) with three kinds of PAN type carbon fibers (CFs) and two kinds of pitch type CFs respectively, were injection-molded into gears. Their gear performance such as the load capability and the wear of tooth were evaluated. The wear properties of PEEK/CF gears extremely varied depending on the kinds of CFs, when the same type gears were combined and grease was initially applied. Also, the load capabilities were significantly influenced by the affinity between PEEK and CF. A composite gear reinforced with CF of the highest density indicated the highest load capability irrespective of the test conditions, due to the lowest abrasive property of the CF as well as the excellent affinity between PEEK and CF. Its load capability under a high temperature running condition was found to be superior to that of polyamideimide (PAI) composite gear or polyphenylenesulphide (PPS) composite gear. 相似文献
103.
α-Synuclein (αSyn) plays a major role in the pathogenesis of Parkinson’s disease (PD), which is the second most common neurodegenerative disease after Alzheimer’s disease. The accumulation of αSyn is a pathological hallmark of PD, and mutations in the SNCA gene encoding αSyn cause familial forms of PD. Moreover, the ectopic expression of αSyn has been demonstrated to mimic several key aspects of PD in experimental model systems. Among the various model systems, Drosophila melanogaster has several advantages for modeling human neurodegenerative diseases. Drosophila has a well-defined nervous system, and numerous tools have been established for its genetic analyses. The rapid generation cycle and short lifespan of Drosophila renders them suitable for high-throughput analyses. PD model flies expressing αSyn have contributed to our understanding of the roles of various disease-associated factors, including genetic and nongenetic factors, in the pathogenesis of PD. In this review, we summarize the molecular pathomechanisms revealed to date using αSyn-expressing Drosophila models of PD, and discuss the possibilities of using these models to demonstrate the biological significance of disease-associated factors. 相似文献
104.
Lindomar R. Damasceno Da Silva Yoshitaka Gushikem Maria Do Carmo Gonalves Ubirajara P. Rodrigues Filho Sandra C. De Castro 《应用聚合物科学杂志》1995,58(10):1669-1673
Interaction of titanium chloride with a cellulose surface and the decurrent modifications introduced on its morphology were studied by scanning, electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The chemical analysis of the surface was carried by X-ray photoelectron spectroscopy (XPS) and changes in the crystallinity upon chemical treatment was determinded by the X-ray diffraction (XRD) technique. Interaction of titanium with cellulose occurs only at the surface and a decrease of its crystallinity was observed with the amount of metal oxide incorporated into the solid matrix. © 1995 John Wiley & Sons, Inc. 相似文献
105.
In order to explain the higher calcium sensitivity of αs2-casein than other casein constituients, properties of αs2-casein and dephosphorylated αs2-casein were examined and compared with those of αs1-casein. αs2-Casein was more sensitive to calcium than αs1-casein. Aggregates of calcium αs1- and αs2-caseinates were both thoroughly solubilized by 4 M urea. Gel filtration of αs1-casein and of αs2-casein in 4 M urea showed the same elution pattern in the presence and absence of 10 mM calcium chloride. Dephosphorylated αs2-casein was insoluble at neutral pH although dephosphorylated αs1-casein was soluble. Dephosphorylated αs2-casein was solubilized by 4 M urea and alkalization to pH 11. The net proton charge, calculated from the primary structure, of dephosphorylated αs2-casein was very low at pH 7.0, although dephosphorylated αs1-casein has a considerable number of negative net charges. The calculated isoionic point of dephosphorylated αs2-casein, which contains one phosphate group, was 6.98. Ester phosphate groups of αs2-casein play an important role in its solubilization at neutral pH and neutralization of ionized phosphate groups by calcium ion increases hydrophobic interaction, which leads to precipitation. 相似文献
106.
The dc brushless motor, permanent magnet-type synchronous motor (PM motor), has been used widely in industrial robots, the machine tools for factory, and factory automations. Therefore, it is more desirable to improve the performance of the PM motor variable speed control system. Although only the torque component current is adjusted as the control method for the PM motor, so-called Vector Control, it is expected that the developed characteristics will be added to the PM motor. In this paper, new driving methods for the PM motor and a new design method for the variable speed control system are presented. The new motor driving methods which bring to the PM motor a new driving performance, e.g., a quick transient response or high-efficiency motor driving, can be implemented by controlling not only the torque component current, but also the magnetizing component current. A developed optimal control theory, i.e., the error system technique, is employed for designing the control system. The control law is endowed with a steady robustness against the variation of the system parameters and the ability of compensating the delay time due to the control processing. The effectiveness of the proposed method is confirmed by simulations and experiments. 相似文献
107.
Ultra‐high‐resolution 1058‐ppi OLED displays with 2.78‐in size using CAAC‐IGZO FETs with tandem OLED device and single OLED device 下载免费PDF全文
Kohei Yokoyama Shinichi Hirasa Noriko Miyairi Yoshitaka Dozen Toshiki Sasaki Yasuhiro Jimbo Kouhei Toyotaka Makoto Kaneyasu Hiroyuki Miyake Satoshi Seo Yoshiharu Hirakata Shunpei Yamazaki Masataka Nakada Takahiro Sato Naoto Goto 《Journal of the Society for Information Display》2016,24(3):159-167
We fabricated new 2.78‐in 1058‐ppi organic light‐emitting diode (OLED) displays. The displays used OLED devices with a tandem structure and a single structure and a field effect transistor (FET) using c‐axis aligned crystalline In–Ga–Zn–O (CAAC‐IGZO) for an active layer and employing the 1.5‐µm rule over a glass substrate. Even in the displays with such high resolution exceeding 1000 ppi, crosstalk that was observed in the lower luminance region was suppressed. The displays achieved high color reproducibility and reduced viewing angle dependence. 相似文献
108.
Ryo Takata Anita Neumann Dennis Weber Duy‐Vu Pham Ralf Anselmann Yoshitaka Kitamura Takashi Kakimura Satoshi Suzuki Shigeki Minami Mitsumasa Kodama 《Journal of the Society for Information Display》2016,24(6):381-385
An indium oxide‐based precursor solution has been developed by spin coating method. In order to apply this material to mass production, material, process, and equipment optimizations for slot die coating have been implemented. Slot die coating is a cost‐effective and scalable process and already applied to photoresist materials in the display industry. The indium oxide‐based precursor solution has been coated on bare glasses and thin‐film transistor substrates by a mass production‐type slot die coater. Mobility of over 10 cm2/Vs is achieved for the first time for a large area at an annealing temperature of 350 °C. The homogeneity of the film will be presented. 相似文献
109.
Hideaki Itoh Yoshitaka Sakai Toru Kadoya Hisao Fukumoto Hiroshi Wakuya Tatsuya Furukawa 《Artificial Life and Robotics》2017,22(3):327-335
Recently, the optimization-by-inference approach has been proposed as a new means for solving high-dimensional optimization problems quickly. Approximate Inference COntrol (AICO) is one of the most successful and promising methods that implement the optimization-by-inference approach. AICO is able to solve stochastic optimal control problems and has already been successfully used in many applications. However, it is known that the iterative inference of AICO sometimes fails to converge to the optimal solution. To make the optimization more robust, in this paper, we propose to take model uncertainty into account. In AICO, the cost function to be minimized is accurate around a particular state of a given stochastic system, but the accuracy is uncertain in regions far from that state. Because using such an uncertain function is harmful to the convergence, we modify AICO, so that it does not use the function in uncertain regions. Our method is easy to implement and does not add much computational time to the original AICO. Experiments using two different scenarios show that our method substantially improves AICO in terms of the rate at which the algorithm produces convergent results. 相似文献
110.
Copoly(vinyl alcohol–styrenesulfonic acid) resin was prepared by a two-step polymerization, consisting of a suspension polymerization of styrene containing divinylbenzene using tetraethylthiuram disulfide as an initiator and a subsequent block copolymerization of vinyl acetate to the crosslinked polystyrene obtained, followed by sulfonation and saponification. Some reaction conditions in the polymerization of styrene were investigated to obtain copolymer containing more vinyl alcohol units. The catalytic activity of the copolymer on the hydrolysis of dextrin was investigated and found to be increased with increasing amount of vinyl alcohol units and with a lowering degree of crosslinking of the copolymer. The maximum acceleration of rate obtained in the presence of the copolymer was about six times that in the presence of Amberlite 120B. Catalytic activity of the copolymer on hydrolysis of sucrose and methyl acetate were also investigated and found to be comparable each other and lower than that for dextrin. The difference between the activities for dextrin and for sucrose and methyl acetate increased with an increasing amount of vinyl alcohol units in the copolymer. 相似文献