全文获取类型
收费全文 | 741篇 |
免费 | 29篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 36篇 |
综合类 | 3篇 |
化学工业 | 206篇 |
金属工艺 | 14篇 |
机械仪表 | 15篇 |
建筑科学 | 10篇 |
能源动力 | 39篇 |
轻工业 | 53篇 |
水利工程 | 3篇 |
无线电 | 68篇 |
一般工业技术 | 150篇 |
冶金工业 | 38篇 |
原子能技术 | 39篇 |
自动化技术 | 103篇 |
出版年
2022年 | 6篇 |
2021年 | 7篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 25篇 |
2012年 | 35篇 |
2011年 | 45篇 |
2010年 | 28篇 |
2009年 | 27篇 |
2008年 | 31篇 |
2007年 | 30篇 |
2006年 | 25篇 |
2005年 | 26篇 |
2004年 | 35篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 15篇 |
1999年 | 16篇 |
1998年 | 20篇 |
1997年 | 21篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 18篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1968年 | 5篇 |
1965年 | 3篇 |
排序方式: 共有777条查询结果,搜索用时 16 毫秒
21.
Takeo Tokiai Takashi Uesugi Kunihito Koumoto 《Journal of the American Ceramic Society》1995,78(4):1089-1092
High thermoelectric figure of merit semiconducting ceramics of n -type iron disilicide with modified local compositions have been developed. Sintering and annealing of the composite powder composed of iron disilicide and precipitated cobalt (II) hydroxide resulted in the dissolution of excess Co and oxygen into the iron disilicide phase. Excess Co segregated to the grain boundary region, while interstitially incorporated oxygen was distributed homogeneously in the microstructure. The maximum figure of merit achieved was 5.2 × 10−4 /K at 673 K. 相似文献
22.
Arai Kazuhito; Hishida Atsushi; Ishiyama Mariko; Kamata Takeo; Uchikoba Hiroyuki; Fushinobu Shinya; Matsuzawa Hiroshi; Taguchi Hayao 《Protein engineering, design & selection : PEDS》2002,15(1):35-41
Lactobacillus casei allosteric L-lactate dehydrogenase (L-LDH)absolutely requires fructose 1,6-bisphosphate [Fru(1,6)P2] forits catalytic activity under neutral conditions, but exhibitsmarked catalytic activity in the absence of Fru(1,6)P2 underacidic conditions through the homotropic activation effect ofsubstrate pyruvate. In this enzyme, a single amino acid replacement,i.e. that of His205 conserved in the Fru(1,6)P2-binding siteof certain allosteric L-LDHs of lactic acid bacteria with Thr,did not induce a marked loss of the activation effect of Fru(1,6)P2or divalent metal ions, which are potent activators that improvethe activation function of Fru(1,6)P2 under neutral conditions.However, this replacement induced a great loss of the Fru(1,6)P2-independentactivation effect of pyruvate or pyruvate analogs under acidicconditions, consequently indicating an absolute Fru(1,6)P2 requirementfor the enzyme activity. The replacement also induced a significantreduction in the pH-dependent sensitivity of the enzyme to Fru(1,6)P2,through a slight decrease and increase of the Fru(1,6)P2 sensitivityunder acidic and neutral conditions, respectively, indicatingthat His205 is also largely involved in the pH-dependent sensitivityof L.casei L-LDH to Fru(1,6)P2. The role of His205 in the allostericregulation of the enzyme is discussed on the basis of the knowncrystal structures of L-LDHs. 相似文献
23.
Keiichi Tomishige Tomohisa Miyazawa Takeo Kimura Kimio Kunimori Naoto Koizumi Muneyoshi Yamada 《Applied catalysis. B, Environmental》2005,60(3-4):299-307
In the partial oxidation of tar derived from the pyrolysis of cedar wood, the effect of H2S addition was investigated over non-catalyst, steam reforming Ni catalyst, and Rh/CeO2/SiO2 using a fluidized bed reactor. In the non-catalytic gasification, the product distribution was not influenced by the presence of H2S. Steam reforming Ni catalyst was effective for the tar removal without H2S addition, however, the addition of H2S deactivated drastically. In contrast, Rh/CeO2/SiO2 exhibited higher and more stable activity than the Ni catalyst even under the presence of high concentration of H2S (280 ppm). On the Ni catalyst, the adsorption of sulfur was observed by XPS and Ni species was oxidized during the partial oxidation of tar. In the case of Rh/CeO2/SiO2, the adsorption of sulfur was below the detection limit of XPS. This can be related to the self-cleaning of catalyst surface during the circulation in the fluidized bed reactor for the partial oxidation of tar derived from cedar pyrolysis. 相似文献
24.
Poly(vinyl chloride) (PVC) with one or more metal salts added was colored by the action of heat to investigate the stabilization mechanism. The coloration and the color difference of heated PVC compound films varied according to the metal salt added. The decoloration of the colored compound films was advanced markedly in THF, DMF, acetone, and ammonia. On the other hand, the heated achromatic PVC film containing Cd/Ba soaps underwent an opposite change, from colorless to yellow orange, in the above materials. This means that the coloration of heated compound films may result from the formation of some complex (for example, π complex of the polyene with the metal chloride). Furthermore, the colored film with cadmium stearate was decolored by roll mixing with the colored film containing barium stearate. These results indicate that the stabilization with metal soaps may be founded on a physical phenomenon such aa an effect of complementary color. 相似文献
25.
Summary This paper describes the so-called No Catalyst Copolymerization between dioxo-1,1-thiazetidine-1,2(Ethanesultam; ESm) and 2-methyl-2-oxazoline. The copolymerization took place without any added initiator to produce copolymers of MeOZO and ESm. The structure of the copolymer was determined by the IR and NMR spectra, elemental analysis, as well as by the result of an alkaline hydrolysis of the copolymer. The reaction scheme of the copolymerization via zwitterion mechanism (Eq 3–5) was proposed. 相似文献
26.
Masaaki Takehisa Hiromasa Watanabe Hirondo Kurihara Kouichi Yamaguchi Hayato Nakajima Toshiaki Yagi Terutaka Watanabe Takanobu Sugo Takeshi Suwa Shinsaku Maruyama Atsuro Kodama Takeo Shimada Yoshio Maruyama Masamichi Tohei Takeshi Wada Sueo Machi 《应用聚合物科学杂志》1979,24(8):1831-1844
Radiation-induced polymerization of ethylene using aqueous tert-butyl alcohol as medium was carried out in a large-scale pilot plant with a 50-liter central source-type reactor at a pressure of 105 to 395 kg/cm2, temperature of 30° to 80°C, mean dose rate of 4.5 × 104 to 1.9 × 105 rads/hr, ethylene feed rate of 5.5 to 23.5 kg/hr, and medium feed rate of 21 to 102 l./hr. The space–time yield and molecular weight of the polymer were in the range of 4.7 to 16.8 g/l.-hr and 1.3 × 104 to 8.9 × 104, respectively. The space–time yield and molecular weight increased with mean residence time at 30°C, whereas at 80°C they became almost independent of the time. The space–time yield increased with pressure and dose rate, slightly decreased with temperature, and was maximum at ethylene molar fraction of 0.5. The polymer molecular weight increased with pressure and ethylene molar fraction, and decreased with dose rate and temperature. The total amount of deposited polymer on the reactor wall, source case wall, and scraping blades was usually less than 1 kg, which was negligibly small for the analysis of polymerization. Continuous discharge of the polymer slurry and production of fine-powder polyethylene were successfully carried out. In the central source-type reactor, a dose rate of 1.9 × 105 rads/hr was obtained with a 60Co source of ca. 12 kCi. 相似文献
27.
Summary Segmented polymers with random sequences of conjugated and non-conjugated blocks are produced by partial dehydrogenation of poly(-thiophenediyl)benzylidene. The fraction of conjugated block was controlled by the elimination time. The polymers gave photoluminescence. Absorption coefficients of the polymers increased with the rate of dehydrogenation, and the highest fluorescence intensity were achieved around 9 % conjugation conversion. The polymers were characterized by 1H- and 13C-n.m.r. and infrared spectra, and were soluble in common organic solvents, which suggests a good processability. 相似文献
28.
Yoshiyuki Sano Marcekazu Konda Chan Woo Lee Yoshiharu Kimura Takeo Saegusa 《大分子材料与工程》1997,251(1):181-191
A new technique for imparting antistatic properties to poly(ethylene terephthalate) (PET) fiber has been developed. In this technique, blend polyester fibers containing poly(ethylene terephthalate/5-sulfoisophthalate) (SIP-PET) were prepared by blend spinning and then treated with various cationic surfactants in the process of dyeing. The surfactants could effectively be immobilized on the fiber as the counter cations of the sulfonate groups of the 5-sulfoisophthalate (SIP) units and aid the release of static electrons formed in the fiber. Thus, the half-life time (t1/2) of leakage of static charge and the surface resistivity (Rs) of the blend PET fibers became much lower after treating. The best result was obtained with a methylated quaternary ammonium salt of a stearylamine-ethylene oxide (EO) adduct or hydrochloride of a laurylamine-EO adduct as the surfactant of which the number of EO units was around ten. Even after five washing cycles the t1/2 value of the fibers treated with these surfactants was kept lower than 30 s with the Rs value maintained in the order of 1013 Ω cm-2. Therefore, the present technique could be useful for practical production of polyester fibers with “semi-permanent” antistatic properties which can be recovered by re-treatment even if they were lost. 相似文献
29.
A wide view auto‐stereoscopic 3D display with an eye‐tracking system for enhanced horizontal viewing position and viewing distance
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Daichi Suzuki Shuji Hayashi Yosuke Hyodo Shinichiro Oka Takeo Koito Hiroki Sugiyama 《Journal of the Society for Information Display》2016,24(11):657-668
This paper describes the development of auto‐stereoscopic three‐dimensional (3D) display with an eye‐tracking system for not only the X‐axis (right–left) and Y‐axis (up–down) plane directions but also the Z‐axis (forward–backward) direction. In the past, the eye‐tracking 3D system for the XY‐axes plane directions that we had developed had a narrow 3D viewing space in the Z‐axis direction because of occurrence of 3D crosstalk variation on screen. The 3D crosstalk variation on screen was occurred when the viewer's eye position moved back and forth along the Z‐axis direction. The reason was that the liquid crystal (LC) barrier pitch was fixed and the LC barrier was able to control the only barrier aperture position. To solve this problem, we developed the LC barrier that is able to control the barrier pitch as well as the barrier aperture position in real time, corresponding to the viewer's eye position. As a result, the 3D viewing space has achieved to expand up to 320–1016 mm from the display surface in the Z‐axis direction and within a range of ±267 mm in the X‐axis direction. In terms of the Y‐axis direction, the viewing space is not necessary to be considered, because of a stripe‐shaped parallax barrier. 相似文献
30.
Computational Visual Media - Iris folding is an art-form consisting of layered strips of paper, forming a spiral pattern behind an aperture, which can be used to make cards and gift tags. This... 相似文献