全文获取类型
收费全文 | 771篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 36篇 |
综合类 | 1篇 |
化学工业 | 199篇 |
金属工艺 | 21篇 |
机械仪表 | 25篇 |
建筑科学 | 9篇 |
能源动力 | 30篇 |
轻工业 | 83篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 48篇 |
一般工业技术 | 174篇 |
冶金工业 | 88篇 |
原子能技术 | 10篇 |
自动化技术 | 76篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 10篇 |
2018年 | 18篇 |
2017年 | 9篇 |
2016年 | 26篇 |
2015年 | 8篇 |
2014年 | 34篇 |
2013年 | 42篇 |
2012年 | 34篇 |
2011年 | 40篇 |
2010年 | 31篇 |
2009年 | 31篇 |
2008年 | 32篇 |
2007年 | 32篇 |
2006年 | 23篇 |
2005年 | 38篇 |
2004年 | 33篇 |
2003年 | 17篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 20篇 |
1998年 | 41篇 |
1997年 | 25篇 |
1996年 | 14篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有805条查询结果,搜索用时 15 毫秒
71.
Daisuke Hiramatsu Yoichi Uemura Shinji Uemoto Junji Okumoto Takehiko Imai Mikio Kakiuchi Ken Nagakura Masafumi Fujita Toru Otaka 《Electrical Engineering in Japan》2011,177(3):17-27
Two‐pole large generators are extensively used in power utilities. Growing demand for electric power in recent years has led to substantial increases in the capacity of generators. In line with this trend, our company has manufactured two‐pole turbine generators in the 900,000‐kVA to 1,200,000‐kVA classes. As the capacity of generators becomes larger, equivalent circuits are increasingly expected to improve their precision in estimating operation characteristics. The Park model has been widely used as an equivalent circuit model. The Park model with quadrature axis transient reactance $x_{q}^{\prime}$ is claimed to be useful for accurately estimating the load rejection characteristics of turbine generators. However, it is difficult to measure $x_{q}^{\prime}$, few studies based on measured data have appeared. As one of the few examples, we have conducted a measured data on a 500,000‐kVA‐class generator. Recently, the authors obtained test data on $x_{q}^{\prime}$ of a 900,000‐kVA‐class generator. In this study, based on these data, we studied the effect of $x_{q}^{\prime}$ using the finite element method and a transient analysis program (EMTP‐ATP). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(3): 17–27, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21099 相似文献
72.
Md. Zaved Hossain Khan Takuya Nakanishi Shigeki Kuroiwa Yoichi Hoshi Tetsuya Osaka 《Electrochimica acta》2011,(24):8657
The effect of surface modification of indium tin oxide (ITO) electrode on its potential response to tryptophan was investigated for ITO substrates with different surface roughness. It was found that a small difference in surface roughness, between ∼1 and ∼2 nm of Ra evaluated by atomic force microscopy, affects the rest potential of ITO electrode in the electrolyte. A slight difference in In:Sn ratio at the near surface of the ITO substrates, measured by angle-resolved X-ray photoelectron spectrometry and Auger electron spectroscopy is remarkable, and considered to relate with surface roughness. Interestingly, successive modification of the ITO surface with aminopropylsilane and disuccinimidyl suberate, of which essentiality to the potential response to indole compounds we previously reported, improved the stability of the rest potential and enabled the electrodes to respond to tryptophan in case of specimens with Ra values ranging between ∼2 and ∼3 nm but not for those with Ra of ∼1 nm. It was suggested that there are optimum values of effective work function of ITO for specific potential response to tryptophan, which can be obtained by the successive modification of ITO surface. 相似文献
73.
Ken Takahashi Yasushi Minagawa Shigeki Yamada Tsunehiro Unno 《Solar Energy Materials & Solar Cells》2001,66(1-4)
Improvement of efficiency of Al0.36Ga0.64As solar cells is advanced in two aspects of minority-carrier lifetime: reduction of majority-carrier concentration in the emitter and base layers, and reduction of deep levels in the back-surface-field (BSF) layer. A pp−n−n structure is proposed to optimize the use of the effect of reduced majority-carrier concentration, and its effectiveness verified in a preparatory experiment on Al0.3Ga0.7As solar cells. A very poor photoluminescence (PL) decay time (below 0.3 ns) of a BSF layer heavily doped with Si becomes 14-fold longer when Se is applied to the dopant instead of Si, resulting in an improvement of the external quantum efficiency near the absorption edge. These two aspects of this study lead to the realization of 16.6% efficiency under 1-sun, AM 1.5 global conditions with an Al0.36Ga0.64As solar cell. 相似文献
74.
Hideki Murayama Shigeki Tomonoh J. Michael Alford Michael E. Karpuk 《Fullerenes, Nanotubes and Carbon Nanostructures》2005,12(1):1-9
In the last decade, application of fullerenes has been proposed actively in a wide range of areas, and recent developments suggest that many of those applications are to be practical technologies. However, there has been no large-scale production enterprise for commercial usage of fullerenes. High production cost and limited availability of fullerenes have been the main obstacle in the development of the Fullerene Market. Improved flame-based technology leads to the most feasible process for mass production of fullerenes, since it is a continuous process and uses inexpensive hydrocarbons as its starting materials. In May 2003, we started fullerene production in tons and more to supply fullerenes with reasonable price as practical materials for industries. 相似文献
75.
We described previously (H. Imamura, et al., Cancer Res., 54: 3620-3624, 1994) a quantitative and reproducible 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for tumor cell invasiveness that uses a water-repellent, paraffin-treated Chemotaxicell chamber to produce a uniform Matrigel layer. In the present experiments, we studied 71 human gastrointestinal carcinomas, including 53 maintained as xenografts in nude mice and 18 fresh surgical specimens. We found a correlation between metastatic behavior and the percent invasion (PI) calculated from the MTT assay. Tumors producing liver metastases had a significantly higher PI than did tumors without liver metastases (P < 0.01), and seven of nine fresh tumors with a PI greater than 1.0 showed liver metastases within 2 years. No significant correlations were noted between the PI and clinicopathological factors. In the tumor xenografts, type IV collagenase activity was significantly higher in tumors with clinically evident liver metastases than in those without liver metastases (P < 0.05). Colorectal carcinomas with liver metastases and a high PI showed higher expression of matrix metalloproteinase 9 than matrix metalloproteinase 2 as assessed by gelatin zymography. Thus, the invasion-MTT assay is clinically useful for predicting liver metastases. Type IV collagenase plays an important role in the development of liver metastases from human gastrointestinal carcinoma. 相似文献
76.
We hypothesize that the interaction between protein kinase C (PKC) and nitric oxide (NO) plays a role in the modulation of cerebral vascular tone, and the disturbance of this interaction following subarachnoid hemorrhage (SAH) results in vasospasm. To prove this hypothesis with direct evidence, PKC activities of smooth muscle cells of canine basilar arteries in the control and in the SAH groups were measured by an enzyme immunoassay method. N omega-nitro-L arginine (L-NA), an inhibitor of NO production, enhanced PKC activity. This enhancement was inhibited neither by 8-bromo-guanosine 3',5'-cyclic monophosphate (8-bromo-cGMP) nor SIN-1, a NO releasing agent. PKC activity in the SAH was significantly higher than in the control; however, no further enhancement was produced with L-NA. In the SAH, PKC activity was not inhibited either by 8-bromo-cGMP or SIN-1. We conclude that NO maintains an appropriate vascular tone through inactivation of PKC, and that this effect is disturbed following SAH, resulting in PKC-dependent vascular contraction, such as vasospasm. On the other hand, once PKC has been activated, NO precursors do not inhibit PKC. These facts indicate NO inactivates PKC through the inhibition of phosphatidylinositol breakdown. 相似文献
77.
Kazunori Shimamura Shigeki Masaki Hiroya Tanigawa 《International Journal of Satellite Communications and Networking》1991,9(5):355-362
The optimum BISDN teleconference service for business, called hypermedia teleconference, is designed based on research into typical business activities and ATM, the most promising BISDN architecture. Service characteristics are determined by analysing the daily work practices of a large set of businessmen. It is shown that communication tasks occupy 44 per cent of the working day. The analysis further shows that some 60 per cent of all communication tasks could be performed through an advanced digital teleconference service. Hypermedia teleconference is designed to satisfy the needs of business through personal communication terminals and ATM public networks. The terminals effectively allocate the BISDN's high-speed transmission capability between a number of subchannels that realize distributed multipoint connection links and multimedia paths. The terminals use a new variable-bit-rate ATM codec created to realize high quality video. Users can easily create full featured teleconferences without a centralized connection facility. Terminals allow the synergistic combination of video, voice, telewriting, telepointing and document transmission services. 相似文献
78.
K Uemura H Otani K Sakamoto Y Sakanishi T Ota T Kobayashi N Ariyoshi A Shirahata 《Canadian Metallurgical Quarterly》1995,43(11):1173-1177
To our knowledge, this report represents the first confirmed case in Japan of a 15-year-old boy with acute lymphoblastic leukemia (ALL).L3 with hand-mirror cells (HMC) in the bone marrow. HMC lymphoid leukemia is an unusual variant of ALL in which the bone marrow lymphoblasts manifest distinctive hand-mirror morphologic features. HMC lymphoblast is characterized by an asymmetric foot-like cytoplasmic process that extends from the portion of the cell, thus giving it the light-microscopic appearance responsible for its name. Besides ALL, HMC has been reported in acute myeloblastic leukemia (AML), blastic crisis of chronic myelogenous leukemia, non-Hodgkin's lymphoma, and infectious mononucleosis. HMC has been reported to be prevalent in ALL.L1 and L2 as compared with L3. 相似文献
79.
Recovery of liquid fuel from hydrocarbon-rich microalgae by thermochemical liquefaction 总被引:11,自引:0,他引:11
Yutaka Dote Shigeki Sawayama Seiichi Inoue Tomoaki Minowa Shin-ya Yokoyama 《Fuel》1994,73(12):1855-1857
Liquefaction of Botryococcus braunii, a colony-forming microalga, with high moisture content was performed with or without sodium carbonate as a catalyst for conversion into liquid fuel and recovery of hydrocarbons. A greater amount of oil than the content of hydrocarbons in B. braunii (50 wt% db) was obtained, in a yield of 57–64 wt% at 300 °C. The oil was equivalent in quality to petroleum oil. The recovery of hydrocarbons was a maximum (>95%) at 300 °C. 相似文献
80.
Manabu Iguchi Tsuneo Kondoh Zen-Ichiro Morita Keiji Nakajima Kazuharu Hanazaki Tomomasa Uemura Fujio Yamamoto 《Metallurgical and Materials Transactions B》1995,26(2):241-247
Laser Doppler velocimeter (LDV) measurements were made to clarify the fluid flow behavior in a bath subject to centric bottom
gas injection. Correlations of the axial mean velocity and turbulence components in the gas-liquid two-phase flow region,i.e., in the bubbling jet region, were proposed as functions of the inner diameter of nozzle, gas flow rate, and densities of
gas and liquid. Measured values of the flow rate, momentum, and kinetic energy of water rising upward were approximated satisfactorily
by these empirical correlations. In addition, the Reynolds shear stress was calculated and compared with measured values.
Formerly Graduate Student, Osaka University, 相似文献