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84.
M Yasuoka Y Nishimura T Nagaoka K Watari 《Journal of Thermal Analysis and Calorimetry》2006,83(2):407-410
The ceramic industry uses enormous amounts of energy
to produce products at high temperatures. Energy-saving measures based on
sintering process improvements are examined.
Oxide ceramics were irradiated by two different methods
during microwave sintering: intermittent use of the same high power levels
(time-control method) and continuous use of lower, increasing levels of power
(power-control method). We found that: 1) the power consumption and efficiency
of the time-control method were lower than those of the power-control method;
2) the power-control method gave more precise control of temperature under
our experimental conditions; 3) sample densification did not differ greatly
between the two methods; and 4) grain growth did not differ greatly between
the two methods. 相似文献
85.
Murayama H Shimizu K Tsukada N Shimada A Kodama T Kitayama Y 《Chemical communications (Cambridge, England)》2002,(22):2678-2679
A significant effect of clay host was observed on the photocatalytic activity of TiO2; TiO2-pillared fluorine mica exhibited two orders of magnitude higher activity than TiO2 and TiO2-pillared montmorillonite for the photocatalytic degradation of gamma-HCH. 相似文献
86.
Li X Nagaoka K Simon LJ Olindo R Lercher JA Hofmann A Sauer J 《Journal of the American Chemical Society》2005,127(46):16159-16166
Catalytic activation and conversion of light alkanes by sulfated zirconia is unequivocally shown to be initiated by producing small concentrations of olefins. This occurs via stoichiometric oxidative dehydrogenation of butane by SO3 or pyrosulfate groups to butene (present mostly as alkoxy groups), water, and SO2. Thermal desorption and in situ IR spectroscopy have been used to determine all three reaction products. The concentration of butene formed determines both the catalytic activity of sulfated zirconia as well as the deactivation via formation of oligomers. The thermodynamics of the oxidative dehydrogenation of n-butane by different SZ surface structures has been examined by density functional (DFT) calculations. The calculations show that pyrosulfate or re-adsorbed SO3 species have the highest oxidizing ability. 相似文献
87.
In this study, we focused on effect of the molecular weight of polyimide on the gas selectivity of the asymmetric membrane with an oriented surface skin layer prepared at different shear stresses. Asymmetric polyimide membranes, which have a defect‐free surface skin layer supported by a porous substructure, were prepared by a dry/wet phase inversion process. The structures of the asymmetric polyimides consisted of a thin skin layer and a porous substructure characterized by the presence of finger‐voids. The gas selectivities of the asymmetric polyimide membranes increased with an increase in the shear rate or a decrease in the molecular weight, indicating that the oriented polyimide structure in the surface skin layer provided a high size and shape discrimination between the gas molecules. The selectivity values of (O2/N2) and (CO2/CH4) in the asymmetric polyimide membrane prepared from the 7.2 × 104 molecular weight material at 1000 sec?1 shear rate were 12 and 143, respectively. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
88.
The sulfoxides 7b and 7d carrying thiophene or benzothiophene as heteroaromatic nucleophiles, when treated with trifluoroacetic anhydride at room temperature (Pummerer reaction), underwent an intramolecular alkylation in an exclusive manner to yield 4,5,6,7-tetrahydro-7-methyl-4-phenylsulfanylthieno[2,3-c]pyridine-6-carbaldehyde (10) and the corresponding benzothiophene derivative (12b) in high yields, respectively. Thus, this route provides biologically interesting nitrogen heterocycles (1b) and (2b). On the other hand, the sulfoxide (7c) carrying benzofuran as a nucleophile on reaction with TFAA yielded not only the Pummerer-type cyclization product (12a), but also the diastereoisomeric tandem cyclization products (13) and (14) having a noble 11-aza-2-oxa-7-thiatricyclo[4.3.3.0(1,5)]dodecane ring system (B). The formation of these products can be readily rationalized by the intervention of the oxonium ion intermediate (21). 相似文献
89.
Nobuyasu Itoh Takamitsu Otake Yoshie Aoyagi Mayumi Matsuo Takashi Yarita 《Chromatographia》2009,70(7-8):1073-1078
We applied liquid chromatography-dopant-assisted atmospheric pressure photoionization-mass spectrometry to quantify four distinct pesticides (isoprothiolane, fenitrothion, fthalide, and ethophenprox) in unpolished rice flour. Although the effect of acetone as a dopant on enhancement of ionization differed among the pesticides, the analytical results by LC-DA-APPI-MS with a dopant flow rate of 50 μL min?1 were not only repeatable (relative SD < 9%, n = 3) but also comparable to those by gas chromatography–mass spectrometry. 相似文献
90.
3‐Methacryloxypropylpolysilsesquioxane (MA‐PS) was prepared by acid‐ or base‐catalyzed hydrolytic polycondensation of 3‐methacryloxypropyltrimethoxysilane (MAS). MA‐PS coating film was prepared by dip‐coating on organic, metal and inorganic substrates, including poly(ethylene terephthalate), aluminum, stainless steel, and glass. The coating films on poly(ethylene terephthalate) and glass showed high adhesive strength. The hardness of coating films increased with increasing heat treatment temperature, whereas they decreased with increasing H2O/MAS molar ratio. The refractive index of coating films increased with increasing heat treatment temperature. In addition, flat and transparent free‐standing films (0.24–0.27 mm thickness) were prepared from MA‐PS that were crack‐free after heat treatment at 1000 °C. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献