全文获取类型
收费全文 | 1100篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 48篇 |
综合类 | 1篇 |
化学工业 | 286篇 |
金属工艺 | 25篇 |
机械仪表 | 20篇 |
建筑科学 | 24篇 |
能源动力 | 44篇 |
轻工业 | 84篇 |
无线电 | 91篇 |
一般工业技术 | 172篇 |
冶金工业 | 227篇 |
原子能技术 | 37篇 |
自动化技术 | 65篇 |
出版年
2023年 | 3篇 |
2022年 | 20篇 |
2021年 | 20篇 |
2020年 | 15篇 |
2019年 | 5篇 |
2018年 | 16篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 17篇 |
2014年 | 20篇 |
2013年 | 48篇 |
2012年 | 35篇 |
2011年 | 46篇 |
2010年 | 38篇 |
2009年 | 32篇 |
2008年 | 58篇 |
2007年 | 60篇 |
2006年 | 38篇 |
2005年 | 39篇 |
2004年 | 28篇 |
2003年 | 41篇 |
2002年 | 39篇 |
2001年 | 25篇 |
2000年 | 25篇 |
1999年 | 27篇 |
1998年 | 100篇 |
1997年 | 48篇 |
1996年 | 35篇 |
1995年 | 30篇 |
1994年 | 33篇 |
1993年 | 33篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有1124条查询结果,搜索用时 0 毫秒
51.
Lysoglycosphingolipids consist of a sphingoid long-chain base and monosaccharide or complex sugar, and they lack the fatty
acyl group present in native glycosphingolipids. Less than 1 pmol of lyso-Forssman glycolipid and lysoganglioside GM1 were
detected on a thin-layer chromatogram by an enzyme-linked immunochemical coloration method with anti-Forssman glycolipid antibody
(FOM-1) and cholera toxin B subunit, respectively. Each spot between 1 and 100 pmol lyso-Forssman glycolipid was immunostained
as densely as that of the same amount of native Forssman glycolipid. The density of the lyso-Forssman glycolipid spots increased
proportionally with increment in the amount of lysoglycolipid. The density of spots of 0.2–100 pmol lysoganglioside GM1 was
also proportional to the amount of each lyso-GM1 spot. These results indicated that less than 1 to 100 pmol of deacylated
glycosphingolipid was quantifiable by the immunochemical coloration method with sugar chain-specific antibodies. Glycosphingolipid
deacylase, which cleaved an amide bond between the sphingoid long-chain base and fatty acyl chain in ceramide of glycosphingolipid,
was assayed by detecting the lyso-Forssman glycolipid produced. Lipophilic compounds, recovered from an aliquot of the reaction
mixture of Forssman glycolipid and crude enzyme at appropriate times, were analyzed by thin-layer chromatography. It was found
that lyso-Forssman glycolipid was produced in the first 1–2 h by the enzyme and production increased with incubation time.
This coloration method is more sensitive and specific than the visualization method with a non-specific reagent such as orcinol-sulfuric
acid reagent. 相似文献
52.
Yukitoshi Takeshita Takuya Kamisho Seizo Sakata Takashi Sawada Yoshikazu Watanuki Ryuichi Nishio Toshinobu Ueda 《Journal of Coatings Technology and Research》2013,10(4):503-514
To improve alkaline resistance, a newly mixed powder coating film using thermoplastic polyethylene terephthalate (PET) was investigated. Two kinds of polyvinyl butyral (PVB) and two kinds of polyamide (PA) were chosen as the secondary polymer. The melting temperatures (T ms) of these materials were lower than that of primary PET polymer so the mixed powder coating was able to form a dual phase film through a fluidized bed coating process. Microscope and Fourier transform infrared spectroscopy (FTIR) observations revealed that the dual phase structure was indeed successfully formed and there was a secondary layer over the entire surface area of the film. This mixed powder coating film significantly enhanced the alkaline resistance to an environment filled with NaOH solution at 40°C in which a secondary material would be effective in protecting the film. With regard to both alkaline resistance and film formability, PET/PVB was superior to the PET/PA mixture. 相似文献
53.
Yoshitoshi Nakamura Tatsuro Sawada Akihiro Komatsu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(10):1101-1106
In order to develop a method for converting raw starch into ethanol efficiently, direct fermentation of ozonized raw starch using a recombinant yeast was investigated. Ozonolysis was carried out as a pretreatment to convert raw starch into ethanol rapidly and efficiently, and then the effect of the ozone degradation conditions on the degree of polymerization and the amount of amylose in a raw starch was determined. Since the degree of polymerization was low and the amount of amylose was high, raw starch treated with an ozone concentration of 40 gm?3 and an ozonation time of 30 min was the material chosen for alcohol fermentation. Though the recombinant yeast could not convert the untreated raw starch, it converted the soluble starch and the ozonized raw starch at a comparatively high yield into ethanol. About 56% of the ozonized raw starch decomposed, and the ethanol concentration obtained from the ozonized raw starch was markedly greater than that obtained from untreated raw starch. The dynamic behavior of cell growth, substrate degradation, and ethanol production was examined in a continuous culture under various dilution rates, and the optimal dilution rate, ie 0.15 h?1, was determined for maximizing the ethanol productivity (amount of ethanol produced per unit time). © 2002 Society of Chemical Industry 相似文献
54.
Summary: Poly(butylene succinate‐co‐adipate) (PBSA) and organically modified montmorillonite (OMMT) nanocomposites of three different compositions were prepared by melt‐extrusion in a batch mixer. The structure of the nanocomposites was studied using X‐ray diffraction (XRD) and transmission electron microscopy (TEM) that revealed a coexistence of exfoliated and intercalated silicate layers dispersed in the PBSA matrix, regardless of the silicate loading. The degree of crystallinity of PBSA decreases with the addition of OMMT platelets. Dynamic mechanical analysis revealed remarkable increase in flexural storage modulus when compared with that of neat PBSA. Tensile property measurements exhibit substantial increase in stiffness with simultaneous increase in elongation at break of nanocomposites as compared to that of neat PBSA. The effect of clay loading on the melt‐state linear viscoelastic behavior of mixed intercalated/exfoliated nanocomposites was also investigated.
55.
Effects of pressure and temperature on dyeing acrylic fibres with basic dyes in supercritical carbon dioxide 总被引:2,自引:0,他引:2
The dyeing of acrylic fibre with CI Basic Blue 47 has been investigated using an ammonium carboxylate perfluoropolyether as an auxiliary in order to perform the reverse micellar system in supercritical carbon dioxide media. The basic dye was satisfactorily solubilised in the interior of the reverse micelle in the system, and dyeability in the supercritical carbon dioxide media was excellent, even in the absence of a retardant and/or an acid. The optimum proton-rich condition for dyeing of acrylic fabric is performed in reverse micelle aggregates and the proton-rich water pool is suitable for dye uptake by the fibre even without the presence of additives. Changes in glass transition temperature of acrylic fibre in the carbon dioxide media also influence the dyeing behaviour of acrylic fabric. 相似文献
56.
Masahiro Kato Kazuaki Nakagawa Kenji Essaki Yukishige Maezawa Shin Takeda Ryosuke Kogo Yoshikazu Hagiwara 《International Journal of Applied Ceramic Technology》2005,2(6):467-475
We have discovered a series of lithium-containing oxides that immediately react with ambient carbon dioxide (CO2 ) up to 700°C. The products react and return reversibly to the oxides at a temperatures higher than about 700°C. The absorption capacity surpasses that of other CO2 absorbents by a factor of 10. Utilizing these absorbents, the possibility of a CO2 separation system that operates at around 500°C is proposed. It is generally believed that a CO2 separation process operable at temperatures higher than 500°C has the special benefit of a small energy penalty. Moreover, the absorption also proceeds at ambient temperature in the atmospheric environment. This property offers the possibility of many other applications, such as air cleaners or cartridges. Therefore, we think these materials have the potential to make a valuable contribution to the realization of CO2 emission control. 相似文献
57.
Hiroaki Takeda Masataka Ohgaki Takashi Kizuki Kazuaki Hashimoto Yoshitomo Toda Shigekazu Udagawa Kimihiro Yamashita 《Journal of the American Ceramic Society》2000,83(11):2884-2886
The formation process of Ba2 La8 (SiO4 )6 O2 was clarified using thermogravimetry–differential thermal analysis (TG-DTA) and a high-temperature powder X-ray diffraction (HT-XRD) method. Phase changes identified from the HT-XRD data surprisingly corresponded to the weight loss and/or endothermic peaks observed in the TG-DTA curves. Raw material with the composition Ba2 La8 (SiO4 )6 O2 was completely reacted at 1400°C and produced only an apatite-type compound without a secondary phase. Moreover, the synthesis of Ba2+ x La8− x (SiO4 )6 O2−δ crystals with x = 0–2 was attempted using a solid-state reaction. 相似文献
58.
Gotoh N Moroda K Watanabe H Yoshinaga K Tanaka M Mizobe H Ichioka K Tokairin S Wada S 《Journal of oleo science》2008,57(5):293-299
Fatty acids are converted into energy via beta-oxidation. Although almost all natural occurring fatty acids are even-numbered, there are some odd-numbered fatty acids too. The details of the metabolism rate of odd-numbered fatty acids, however, are not clear. In the present study, we simultaneously administered a triacylglycerol containing four types of labeled even-numbered (palmitic acid and stearic acid) and odd-numbered (pentadecanoic acid and heptadecanoic acid) fatty acids to mice to compare the rates of their metabolism. The rates of metabolism were evaluated based on the accumulation of the labeled fatty acids in the small intestine epithelium, liver, and epididymal fat. Odd-numbered fatty acids accumulated mainly in the epididymal fat. In contrast, there was no accumulation of even-numbered fatty acids observed in the small intestine epithelium, liver, or epididymal fat. These results suggest that odd-numbered fatty acids might not be favorable substrates for beta-oxidation-related enzymes. 相似文献
59.
Summary Organocobalt poly(arylene-vinylene)s composed of 1,2- or 1,3- linkage at their cyclobutadiene moieties (3 and 4, respectively) were prepared by the Heck reaction of p-divinylbenzene with (cyclobutadiene)cobalt-containing monomers having two aryl bromide moieties (1 and 2, respectively). The number average molecular weights (M n) of the obtained organocobalt poly(arylene-vinylene)s (3 and 4) were 4,100 and 4,000, respectively (GPC, on the basis of polystyrene). UV-vis spectra of 3 and 4 exhibited main π-π* absorption peaks at 362 and 397 nm, respectively, which were ca. 60 nm bathochromically shifted from those of the corresponding monomeric units. Both polymers were found to show thermotropic liquid crystallinity in the range of room temperature to ca. 80 °C by employing differential scanning calorimetry (DSC) and the optical measurement using crossed polarizers. Received: 2 July 1999/Accepted: 29 July 1999 相似文献
60.
Two‐dimensional numerical computation is performed for unsteady laminar flow. Spatially periodic boundary conditions are adopted in the streamwise direction, and in particular, a criterion for judging the uniqueness of the numerical solution is studied. The following results were obtained. When the numerical result fluctuates with the computational domain size, various low‐frequency components are markedly observed in the streamwise velocity of the calculated result. Compared with the channel flow obstructed by a single rod of the same size, the intensities of velocity fluctuation in this study are relatively high, and their distribution throughout the flow field is rather uniform. The spatially averaged kinematic energy of the velocity fluctuation is adopted as a key parameter, and a discrimination map of the uniqueness of the numerical solution is presented using a timescale ratio between mean flow and velocity fluctuation, the rod pitch, and the blockage ratio. The timescale ratio is well correlated with a geometric parameter obtained from the flow configuration, and the discrimination map can be converted such that the geometric parameter and the channel Reynolds number describe it. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(3): 113–126, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20152 相似文献