全文获取类型
收费全文 | 2931篇 |
免费 | 72篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 152篇 |
综合类 | 4篇 |
化学工业 | 854篇 |
金属工艺 | 94篇 |
机械仪表 | 68篇 |
建筑科学 | 52篇 |
矿业工程 | 3篇 |
能源动力 | 118篇 |
轻工业 | 283篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 165篇 |
一般工业技术 | 620篇 |
冶金工业 | 265篇 |
原子能技术 | 87篇 |
自动化技术 | 230篇 |
出版年
2023年 | 11篇 |
2022年 | 39篇 |
2021年 | 51篇 |
2020年 | 33篇 |
2019年 | 48篇 |
2018年 | 48篇 |
2017年 | 43篇 |
2016年 | 57篇 |
2015年 | 51篇 |
2014年 | 77篇 |
2013年 | 152篇 |
2012年 | 125篇 |
2011年 | 159篇 |
2010年 | 146篇 |
2009年 | 152篇 |
2008年 | 151篇 |
2007年 | 141篇 |
2006年 | 127篇 |
2005年 | 105篇 |
2004年 | 101篇 |
2003年 | 85篇 |
2002年 | 88篇 |
2001年 | 61篇 |
2000年 | 60篇 |
1999年 | 60篇 |
1998年 | 152篇 |
1997年 | 76篇 |
1996年 | 84篇 |
1995年 | 50篇 |
1994年 | 43篇 |
1993年 | 39篇 |
1992年 | 34篇 |
1991年 | 38篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 15篇 |
1987年 | 26篇 |
1986年 | 23篇 |
1985年 | 19篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1982年 | 27篇 |
1981年 | 19篇 |
1980年 | 20篇 |
1979年 | 19篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1974年 | 6篇 |
1910年 | 6篇 |
排序方式: 共有3011条查询结果,搜索用时 6 毫秒
101.
102.
Beata Tryba Antoni W. Morawski Michio Inagaki Masahiro Toyoda 《Applied catalysis. B, Environmental》2006,63(3-4):215-221
H2O2 used in the photo-Fenton reaction with iron catalyst can accelerate the oxidation of Fe2+ to Fe3+ under UV irradiation and in the dark (in the so called dark Fenton process). It was proved that conversion of phenol under UV irradiation in the presence of H2O2 predominantly produces highly hydrophilic products and catechol, which can accelerate the rate of phenol decomposition. However, while H2O2 under UV irradiation could decompose phenol to highly hydrophilic products and dihydroxybenzenes in a very short time, complete mineralization proceeded rather slowly. When H2O2 is used for phenol decomposition in the presence of TiO2 and Fe–TiO2, decrease of OH radicals formed on the surface of TiO2 and Fe–TiO2 has been observed and photodecomposition of phenol is slowed down. In case of phenol decomposition under UV irradiation on Fe–C–TiO2 photocatalyst in the presence of H2O2, marked acceleration of the decomposition rate is observed due to the photo-Fenton reactions: Fe2+ is likely oxidized to Fe3+, which is then efficiently recycled to Fe2+ by the intermediate products formed during phenol decomposition, such as hydroquinone (HQ) and catechol. 相似文献
103.
Koji Fushimi Takatoshi Shimada Hiroki Habazaki Hidetaka Konno Masahiro Seo 《Electrochimica acta》2011,(4):1773
Depassivation–repassivation of iron surfaces in boric–borate solutions were investigated by using the micro-indentation test. A pair of current peaks due to repair of the passive film following rupture of the film were observed during a series of indenter drives, i.e., loading and unloading of the indenter. The shape of the current peak depended on environmental conditions (conductivity and pH of the solution) and substrate conditions (mechanical processing history, alloyed element) as well as indentation conditions (repetition, maximum depth, and maximum load). Plastic deformation of the surface was accompanied by surface depassivation, while no depassivation occurred during the elastic deformation, indicating that the passive film on iron has a ductile property. The solution conditions did not affect the scale of depassivation but affected the rate of repassivation. Dislocations in the substrate made surface depassivation difficult but enhanced reactivity during the repassivation. The test also revealed that type-312L stainless steel has high corrosion resistance in a concentrated NaCl solution. 相似文献
104.
Yunosuke Abe Toshiki Aoki Hongge Jia Shingo Hadano Takeshi Namikoshi Yuriko Kakihana Lijia Liu Yu Zang Masahiro Teraguchi Takashi Kaneko 《Polymer》2012,53(11):2129-2133
A soluble and stable one-handed helical conjugated polymer without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer having two hydroxyl groups followed by desubstitution of the chiral groups in a solid membrane state. The reason for the success was the polymer reaction was carried out in the membrane state. This is an alternative method to obtain such a unique chiral polymer which was obtained only by the helix-sense-selective polymerization (HSSP) we reported before. In addition the efficiency of the chiral induction was higher than that of the HSSP. It is interesting that the “Membrane state” acted like as if a protecting group. 相似文献
105.
Cheol Ho Pyeon Masao Yamanaka Akito Oizumi Masahiro Fukushima Go Chiba Kenichi Watanabe 《Journal of Nuclear Science and Technology》2019,56(8):684-689
This study demonstrates, for the first time, the principle of nuclear transmutation of minor actinide (MA) by the accelerator-driven system (ADS) through the injection of high-energy neutrons into the subcritical core at the Kyoto University Critical Assembly. The main objective of the experiments is to confirm fission reactions of neptunium-237 (237Np) and americium-241 (241Am), and capture reactions of 237Np. Subcritical irradiation of 237Np and 241Am foils is conducted in a hard spectrum core with the use of the back-to-back fission chamber that obtains simultaneously two signals from specially installed test (237Np or 241Am) and reference (uranium-235) foils. The first nuclear transmutation of 237Np and 241Am by ADS soundly implemented by combining the subcritical core and the 100 MeV proton accelerator, and the use of a lead-bismuth target, is conclusively demonstrated through the experimental results of fission and capture reaction events. 相似文献
106.
Bacterial alkaline phosphatase (BAP) was site-specifically and covalently immobilized on magnetic particles (MPs) using the enzymatic reaction of microbial transglutaminase (MTG). Immobilization efficiency was affected by the chemical surface treatment of MPs and immobilized BAP exhibited more than 90% of the initial activity after 10 rounds of recycling. 相似文献
107.
ABSTRACT: The volatile compounds of sweetened condensed milk (SCM) were investigated to explain their contribution to SCM flavor. Commercially processed SCM was diluted with water and the volatiles were isolated by simultaneous steam distillation-extraction under reduced pressure. Commercial liquid milk was used for comparison. The odor concentrate was analyzed by GC and GC-MS, and then fractionated by silica gel TLC and preparative GC to determine the contributors to SCM flavor. Major volatile compounds were 10 fatty acids, 14 lactones, 10 ketones, 13 hydrocarbons, 8 alcohols, 4 aldehydes, and 8 miscellaneous compounds. δ-Decalactone and δ-dodecalactone were the principal contributors to SCM flavor although the other lactones may contribute as well. 相似文献
108.
A multi-port D-R mutator with new current conveyors (CFCCIIs) as the four-port active element is proposed. Each CFCCII consists of a current follower added to a second-generation current conveyor (CCII). This proposed circuit is a simple configuration using CCIIs, CFCCIIs and grounded capacitances and is applied to higher order high-pass filters. This configuration can realize a superior transmission characteristic, inheriting the characteristic of the conventional LC filter. Since all the passive elements are grounded, the influence of parasitic elements of current conveyors can be reduced with this circuit configuration. As a result, this circuit is considered a suitable configuration for monolithic integration. Results obtained from the SPICE simulations show the realized filters have excellent performance and the circuit is effective. 相似文献
109.
Mike Tien-Chien Lee Yu-Chin Hsu Ben Chen Masahiro Fujita 《Design Automation for Embedded Systems》1997,2(3-4):319-338
ATM switch, the core technology of an ATM networking system, is one of the major products in Fujitsu telecommunication business. However, current gate–level design methodology can no longer satisfy its stringent time–to–market requirement. It becomes necessary to exploit high–level methodology to specify and synthesize the design at an abstraction level higher than logic gates. This paper presents our prototyping experience on domain–specific high–level modeling and synthesis for Fujitsu ATM switch design. We propose a high–level design methodology using VHDL, where ATM switch architectural features are considered during behavior modeling, and a high–level synthesis compiler, MEBS, is prototyped to synthesize the behavior model down to a gate–level implementation. Since the specific ATM switch architecture is incorporated into both modeling and synthesis phases, a high–quality design is efficiently derived. The synthesis results shows that given the design constraints, the proposed high–level design methodology can produce a gate–level implementation by MEBS with about 15 percent area reduction in shorter design cycle when compared with manual design. 相似文献
110.
Yudai Yoshimura Yasunori TakedaKenjiro Fukuda Daisuke KumakiShizuo Tokito 《Organic Electronics》2014,15(11):2696-2701
We have demonstrated fast operation of printed organic inverter circuits. We employ a soluble organic semiconducting material which has high field-effect mobility and ink-jet printed source/drain electrodes with short channel length. Appropriate concentration of the semiconducting solution and modification layer of source/drain electrodes improve both mobility and on/off ratio. The fabricated transistors with a short channel length (4 μm) exhibit excellent mobility (1.2 cm2/V s), high on/off ratio (>105) and operational stability. The diode-load inverter with a narrow channel and low parasitic capacitance operate at 8 kHz at 20 V. These results will lead to significant progress in applications of printed organic circuits. 相似文献