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131.
添加剂铜和银离子对MnO2催化燃烧CH4的影响 总被引:2,自引:1,他引:2
催化燃烧法,由于起燃温度低、去除率高、适用氧浓度范围大、无二次污染、燃烧缓和等,是国内外治理有机废气时,回收利用能量最有效的方法之一[1].但目前用于该过程的催化剂中均含有来源有限、价格昂贵的贵金属铂或钯[2].因此,寻找来源丰富、价格低廉、性能相当... 相似文献
132.
Thermochemistry of the solid complex Gd(Et<Subscript>2</Subscript>dtc)<Subscript>3</Subscript>(phen)
Summary A ternary solid complex Gd(Et2dtc)3(phen) has been obtained from reactions of sodium diethyldithiocarbamate (NaEt2dtc), 1,10-phenanthroline (phen) and hydrated gadolinium chloride in absolute ethanol. The title complex was described by chemical and elemental analyses, TG-DTG and IR spectrum. The enthalpy change of liquid-phase reaction of formation of the complex, ΔrHΘm(l), was determined as (-11.628±0.0204) kJ mol-1 at 298.15 K by a RD-496 III heat conduction microcalorimeter. The enthalpy change of the solid-phase reaction of formation of the complex, ΔrHΘm(s), was calculated as (145.306±0.519) kJ mol-1 on the basis of a designed thermochemical cycle. The thermodynamics of reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A), the reaction order (n), the activation enthalpy (ΔrHΘ≠), the activation entropy (ΔrSΘ≠), the activation free energy (ΔrGΘ≠) and the enthalpy (ΔrHΘ≠), were obtained by combination of the thermodynamic and kinetic equations for the reaction with the data of thermokinetic experiments. The constant-volume combustion energy of the complex, ΔcU, was determined as (-18673.71±8.15) kJ mol-1 by a RBC-II rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, ΔcHΘm, and standard enthalpy of formation, ΔfHΘm, were calculated to be (-18692.92±8.15) kJ mol-1 and (-51.28±9.17) kJ mol-1, respectively. 相似文献
133.
《Surface and interface analysis : SIA》2003,35(2):216-225
Catalysts of Co,K/La2O3 have been prepared by wet impregnation. The samples have been calcined at 400°C and 700°C and have been characterized for phase composition using x‐ray diffraction and Fourier transform infrared spectroscopy. The XPS analysis of the samples has been obtained by examination of the O 1s, K 2p, C 1s and La 3d spectral regions. The XPS data are discussed with respect to the calcination temperatures and the soot combustion performed in the spectrometer reaction chamber. Analysis of the XPS data indicates considerable carbonation of the surfaces of all samples, even after burning the soot. The K/La2O3 solid presents the highest content of surface carbonated species, showing the highest catalytic activity for soot combustion. Interaction of the catalysts with CO2 is studied by temperature‐programmed desorption and microbalance experiments. Kinetic studies and surface characterization of the potassium‐containing samples suggest that an appropriate surface potassium concentration is necessary for a synergetic action between potassium and lanthanum. In the cobalt‐containing catalysts calcined at 700°C, an increase is observed in the concentration of the outer‐layer perovskite species when the potassium content increases, following the same tendency observed in the bulk. Such LaCoO3 species would limit the reaction of lanthanum with CO2. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
134.
135.
《Electroanalysis》2005,17(3):239-245
Oxygen dependence of a tyrosinase‐based electrochemical biosensor for determination of phenol in aqueous and organic media was systematically investigated. The result demonstrated that the enzymatic coupling reaction rate of tyrosinase (deoxy form) and O2 to regenerate tyrosinase (oxy form) is a kinetically fast reaction, and the significant change of O2 concentration in aqueous solution did not affect the coupling reaction. The further increase of O2 concentration did not increase the overall oxidation reaction rate of the substrate at low substrate concentration (e.g.,<10 μM phenol) when O2 concentration was greater than 8.9 ppm. The oxygen dependence was observed in the case of high substrate concentration due to insufficient amount of O2 available for the regeneration of tyrosinase. In other words, the upper linear range is oxygen dependent for tyrosinase biosensors. The phenol biosensors employing microelectrodes had wider upper linear ranges than macroelectrodes in both aqueous and organic phase, which can be explained by the oxygen dependence. 相似文献
136.
氧化条件下NOx催化的甲烷均相部分氧化 总被引:2,自引:0,他引:2
考察了没有固体催化剂时NOx对甲烷气相氧化的促进作用.实验结果表明,即使在强氧化条件下(O2/CH4=5),NOx对甲烷部分氧化制一氧化碳仍然有明显的催化活性.在CH4-O2体系中加入0.005%~0.2%的NO后,反应温度可降低200-300 ℃.在反应产物中还可观察到甲醛和乙烯,通过改变反应条件可以控制它们的相对浓度. 相似文献
137.
A study on the synthesis of La1−xAgxMnO3+δ (x = 0, 0.2) using a microwave process (MWhyd) has been carried out by comparing the heating time and reaction temperature with the same factor under conventional thermal process (CHhyd). Experiments have been conducted using the hydrothermal method at medium pressure (T = 200 °C, P = 20 atm) followed by a thermal treatment of the precursor at 700 °C (10 h).Structural and physico-chemical properties of the catalysts were investigated using X-ray diffraction (XRD), BET sorption, temperature-programmed reduction or desorption, mass spectrometry (TPR-MS and TPD-MS), and X-ray photoelectron spectroscopy (XPS). While CHhyd and MWhyd powder catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation method. The effect of the nature of oxygen species, their amount and mobility, evidenced by temperature programmed experiments, on the catalytic properties in methane combustion in the presence and in the absence of hydrogen sulphide has been studied. MWhyd-La0.8Ag0.2MnO3+δ catalysts were found to exhibit a much better performance in methane combustion together with higher resistance to sulphur poisoning than CHhyd catalysts. 相似文献
138.
Hiroto Yoshida 《Tetrahedron》2007,63(22):4793-4805
A variety of aldehydes, ketones, benzoquinones, or sulfonylimines were found to couple with arynes and isocyanides, giving iminodihydroisobenzofuran or iminoisoindoline derivatives of structural diversity in a straightforward manner. Nucleophilic addition of isocyanides to arynes, a first step of the three-component coupling, was proved to be reversible by the reaction of an unsymmetrical aryne. 相似文献
139.
Delano P. Chong 《中国化学会会志》1992,39(5):457-459
The vertical ionization potentials of OF2, HNF2, and CH2F2 were computed by the deMon density functional program. The results are compared with earlier calculations and with experiment. The average absolute deviation of the 21 computed ionization potentials of the outer valence electrons from experiment is 0.44 eV, which compares well with 0.37 eV for frozen-orbital configuration-interaction calculations. Although this performance is not as good as perturbation corrections to Koopmans' theorem, the computation requirements are much less demanding. 相似文献
140.
Wei-Cho Huang Cheng S. Gong George T. Tsao 《Applied biochemistry and biotechnology》2003,106(1-3):471-480
Pressure pulsation (PP) was investigated for its effects on oxygen transfer rate (OTR) measured by sulfite oxidation. By manipulating
airflow rate, 0.41–1.2 vvm, and a control valve in a 4-L bioreactor, the frequency of PP was varied at different gas pressures3–15
psig. A mathematical model of OTR was built and compared to experimental data. OTR was also examined at constant gas pressure,
4.5–15.0 psig. The results indicate a good agreement between measurement and model prediction. OTR above 9 psig during PP
showed significant enhancement at 25°C. This proves that PP not only affects the elevation of DO level, but also increases
the interfacial area and mass transfer coefficient. 相似文献