全文获取类型
收费全文 | 1483篇 |
免费 | 40篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 88篇 |
综合类 | 3篇 |
化学工业 | 359篇 |
金属工艺 | 46篇 |
机械仪表 | 27篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 95篇 |
轻工业 | 106篇 |
水利工程 | 3篇 |
石油天然气 | 6篇 |
无线电 | 85篇 |
一般工业技术 | 239篇 |
冶金工业 | 262篇 |
原子能技术 | 58篇 |
自动化技术 | 125篇 |
出版年
2023年 | 7篇 |
2022年 | 8篇 |
2021年 | 36篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 18篇 |
2017年 | 26篇 |
2016年 | 19篇 |
2015年 | 15篇 |
2014年 | 33篇 |
2013年 | 77篇 |
2012年 | 69篇 |
2011年 | 87篇 |
2010年 | 54篇 |
2009年 | 56篇 |
2008年 | 62篇 |
2007年 | 65篇 |
2006年 | 74篇 |
2005年 | 58篇 |
2004年 | 34篇 |
2003年 | 41篇 |
2002年 | 45篇 |
2001年 | 25篇 |
2000年 | 34篇 |
1999年 | 35篇 |
1998年 | 100篇 |
1997年 | 67篇 |
1996年 | 46篇 |
1995年 | 37篇 |
1994年 | 31篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1966年 | 2篇 |
排序方式: 共有1532条查询结果,搜索用时 31 毫秒
71.
Takahiro Kuriiwa Takahiro Maruyama Atsunori Kamegawa Masuo Okada 《International Journal of Hydrogen Energy》2010
Hydrogen storage is one of the most important issues to realize hydrogen society especially for on-board usage. Recently, high-pressure metal hydride (MH) tank attracts many attentions due to its high volumetric hydrogen storage density and relatively easy heat management. To emphasize its merits, further improvements of properties of MH, such as capacity, hydrogen desorption capability at low temperature and durability, are required. In this paper, V–Ti–Cr alloys of V-rich compositions were investigated with perspective of increasing of hydrogen desorption pressure and durability. In both of 60at%V–Ti–Cr and 80at%V–Ti–Cr alloys, good relationship between hydrogen desorption pressure and Ti content was observed. In comparing with 60at%V–Ti–Cr alloys, 80at%V–Ti–Cr alloys showed good durability. It is quite notable that relationship between limitation line (upper substitution limit of Ti by Cr without degradation of hydrogen capacity) and desorption pressure for V–Ti–Cr ternary system with V-rich composition is clarified. And also, it is revealed that in the case of V–Ti–Cr ternary system, not only Ti/Cr ratio but also V content is important factor to obtain alloys with high hydrogen desorption pressure. 75at%V–5at%Ti–Cr as-cast sample showed good durability, hydrogen desorption capability at low temperature and relatively high effective hydrogen capacity simultaneously. 相似文献
72.
Norio Maruyama Sachiko Hiromoto Eiji Akiyama Morihiko Nakamura 《Science and Technology of Advanced Materials》2013,14(2)
AbstractFretting fatigue behaviour of Ni-free high-nitrogen steel (HNS) with a yield strength of about 800 MPa, which was prepared by nitrogen gas pressurized electroslag remelting, was studied in air and in phosphate-buffered saline (PBS(-)). For comparison, fretting fatigue behaviour of cold-rolled SUS316L steel (SUS316L(CR)) with similar yield strength was examined. The plain fatigue limit of HNS was slightly lower than that of SUS316L(CR) although the former had a higher tensile strength than the latter. The fretting fatigue limit of HNS was higher than that of SUS316L(CR) both in air and in PBS(-). A decrease in fatigue limit of HNS by fretting was significantly smaller than that of SUS316L(CR) in both environments, indicating that HNS has better fretting fatigue resistance than SUS316L(CR). The decrease in fatigue limit by fretting is discussed taking into account the effect of friction stress due to fretting and the additional influences of wear, tribocorrosion and plastic deformation in the fretted area. 相似文献
73.
Katsunori Takeda Tetsuo Hattori Tetsuya Izumi Hiromichi Kawano Shinichi Masuda 《Artificial Life and Robotics》2010,15(4):421-424
Recently, remote monitoring camera systems have been widely used for security. In such systems, one important function is
that the system automatically detects any change in the scenes from the monitoring cameras. In wireless remote monitoring
camera systems, the images of the scenes are generally transmitted as compressed data (e.g., JPEG file), because of the capacity
of the wireless channel. This article shows the automated detection of the change point in time-series data of compressed
JPEG file quantity (Kbytes) from the monitoring camera by applying the sequential probabilistic ratio test (SPRT) and the
Chow test, which is well known as a standard method for detecting structural change in time-series data. 相似文献
74.
Shinichi Komaba Naoaki Yabuuchi Tomoaki Ozeki Koji Okushi Hiroharu Yui Kozo Konno Yasushi Katayama Takashi Miura 《Journal of power sources》2010,195(18):6069-6074
Poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), and poly(vinyl alcohol) (PVA), which have oxygen species as functional groups, were utilized as a binder for graphite electrodes, and the electrochemical reversibility of lithium intercalation was examined in PC medium and ionic liquid electrolyte, lithium bis(trifluoromethanesulfonyl)amide dissolved in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide (BMP-TFSA). Columbic efficiency of 75–80% with more than 300 mAh g?1 was achieved upon first reduction/oxidation cycle in both electrolytes using these binding polymers, which were significantly improved in comparison to a conventional PVdF binder (less than 45% of columbic efficiency for the first cycle). For the graphite-PVdF electrode, co-intercalation and/or decomposition of PC molecules solvating to Li ions were observed by the electrochemical reduction, resulting in the cracking of graphite particles. In contrast, the co-intercalation and decomposition of PC molecules and BMP cations for the first reduction process were completely suppressed for the graphite electrodes prepared with the polymers containing oxygen atoms. It was proposed that the selective permeability of lithium ions was attained by the uniform coating of the graphite particles with PAA, PMA, and PVA polymers, because the electrostatic interaction between the positively charged lithium ions and negatively charged oxygen atom in the polymer should modulate the desolvation process of lithium ions during the lithium intercalation into graphite, showing the similar functions like artificial solid-electrolyte interphase. 相似文献
75.
76.
This analysis provides time-series data on electric efficiencies for 138 countries and regions, covering all fossil fuels for the period 1971–2005, with an emphasis on non-Organization for Economic Cooperation and Development (OECD) countries. Fossil fuel consumption for electricity generation in non-OECD countries now exceeds that in the OECD. The historical performance of the top five non-OECD consumers of each fossil fuel for which reliable data are available is presented and discussed. For each fuel, the countries that lead the world in efficiency are used for benchmarks; bringing the rest of the world up to these standards would result in energy savings of 26 EJ (equivalent to 5% of global energy consumption) and CO2 emissions reduction of 2.1 Pg (equivalent to 8% of global CO2 emissions). Coal showed the largest potential margin of improvement for both energy and CO2, with possible savings equivalent to 3% of current global energy consumption and 5% of global CO2 emissions. The gap in electric efficiency between OECD and non-OECD countries over the past 35 years has widened for coal-fired generation, stayed relatively constant for natural gas, but has shrunk for petroleum. The results show the very gradual nature of overall efficiency improvements and the significant differences among regions and countries. 相似文献
77.
Onoue Y Shindo R Teranishi H Furukawa I Hasegawa Y Maruyama T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(4):239-242
The efficacy of Baird-Parker (BP) agar, mannitol-salt-egg yolk (MSEY) agar and mannitol salt (MS) agar in detecting Staphylococcus aureus FRI-100 heated at 52 degrees C for 20 min in 100 mmol/L potassium phosphate buffer was determined. Brain heart infusion agar with 1% pyruvate (BHIP agar) supported the highest recovery of injured cells and was used as the control medium. Of the three selective media, significantly higher recovery of heat-injured cells was observed on BP agar than MSEY agar, and the poorest recovery was observed on MS agar (p < 0.05). Low recovery of unheated cells was obtained for MS compared with other media (p < 0.05). A reduction in populations occurred gradually in reagent-grade water stored for 14 days at -20 degrees C. There was no significant difference between BHIP agar and MS agar in the number of freeze-injured cells recovered from 1 to 14 days. 相似文献
78.
Kiyofumi Moriyama Hideo Nakamura Yu Maruyama 《Nuclear Engineering and Design》2006,236(19-21):2010-2025
A computer code JASMINE-pre was developed for the prediction of premixing conditions of fuel–coolant interactions and debris bed formation behavior relevant to severe accidents of light water reactors. In JASMINE-pre code, a melt model which consists of three components of sub-models for melt jet, melt particles and melt pool, is coupled with a two-phase flow model derived from ACE-3D code developed at JAERI. The melt jet and melt pool models are one-dimensional representations of a molten core stream falling into a water pool and a continuous melt body agglomerated on the bottom, respectively. The melt particles generated by the melt jet break-up are modeled based on a Lagrangian grouped particle concept. Additionally, a simplified model pmjet was developed which considers only steady state break-up of the melt jet, cooling and settlement of particles in a stationary water pool. The FARO corium quenching experiments with a saturation temperature water pool and a subcooled water pool were simulated with JASMINE-pre and pmjet. JASMINE-pre reproduced the pressurization and fragmentation behavior observed in the experiments with a reasonable accuracy. Also, the influences of model parameters on the pressurization and fragmentation were examined. The calculation results showed a quasi-steady state phase of melt jet break-up during which the amount of molten mass contained in the premixture was kept almost constant, and the steady state molten premixed masses evaluated by JASMINE-pre and pmjet agreed well. 相似文献
79.
Kazunori Komatani Shinichi Ueno Tatsuya Kawahara Hiroshi G. Okuno 《User Modeling and User-Adapted Interaction》2005,15(1-2):169-183
We address the issue of appropriate user modeling to generate cooperative responses to users in spoken dialogue systems. Unlike
previous studies that have focused on a user’s knowledge, we propose more generalized modeling. We specifically set up three
dimensions for user models: the skill level in use of the system, the knowledge level about the target domain, and the degree of urgency. Moreover, the models are automatically derived by decision tree learning using actual dialogue data collected by the system.
We obtained reasonable accuracy in classification for all dimensions. Dialogue strategies based on user modeling were implemented
on the Kyoto City Bus Information System that was developed at our laboratory. Experimental evaluations revealed that the
cooperative responses adapted to each subject type served as good guides for novices without increasing the duration dialogue
lasted for skilled users. 相似文献
80.
BACKGROUND: Positron emission tomography (PET) allows the measurement of benzodiazepine-gamma-aminobutyric acidA (GABA(A)) receptor kinetics. We employed flumazenil radiolabeled with carbon 11, a radioligand that labels the benzodiazepine site on the GABA(A) receptor, and fully quantitative, high-sensitivity PET to test the hypothesis that central benzodiazepine site binding is decreased in medication-free patients with panic disorder. METHODS: We compared 7 patients with panic disorder who had been off medication for at least 6 months and who had never abused alcohol with 8 healthy controls. The resulting parametric voxel-by-voxel maps were analyzed by voxel-based and region of interest-based methods using both parametric and nonparametric statistics. RESULTS: The major finding was that there is a global reduction in benzodiazepine site binding throughout the brain in patients with panic disorder compared with controls. There were sex differences in the 2 samples, but a separate analysis excluding women led to the same conclusions. In addition, the loci with the largest regional decrease in binding (right orbitofrontal cortex and right insula) were areas thought to be essential in the central mediation of anxiety. CONCLUSION: These results must be considered preliminary but are congruous with previous clinical psychopharmacologic evidence of involvement of the benzodiazepine-GABA(A) receptor and demonstrate that decreased flumazenil binding at this site may underlie panic disorder. 相似文献