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1.
V Correcher J Garcia-Guinea FJ Valle-Fuentes 《Journal of Thermal Analysis and Calorimetry》2006,83(2):439-444
In
this paper, novel results on the blue thermally stimulated luminescence (TSL)
emission of ulexite (NaCaB5O6(OH)6·5H2O)
have been studied. The four maxima appearing at 60, 110, 200 and 240°C
on the TSL glow curves of this borate could be respectively associated to:
(i) the first dehydration (NaCaB5O6(OH)6·5H2O→NaCaB5O6(OH)6·3H2O),
(ii) the creation-annihilation of the three-hydrated
phase, (iii) the Na-coordinated chains
dehydroxylation and the starting point of the alkali self-diffusion through
the lattice and (iv) the amorphisation
of the lattice. These results are fairly well correlated with the differential
thermal analyses (DTA), in situ thermal observations under environmental scanning
electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques. 相似文献
2.
3.
Reduced charge montmorillonites (RCM) were prepared by the thermal treatment of lithiumsaturated montmorillonite. Samples prepared by mild thermal treatment with lithium contained more water sorbed than the original montmorrilonite. When RCMs were prepared, part of the lithium cations reacted with hydroxyl groups in the octahedral sheet and released protons, which reacted with the structure. Acid treatment probably enhanced the surface area. which was reflected in the amount of water sorbed. Deprotonation of hydroxyl groups was proved by the measurements of the ignition loss. The heating of lithium saturated montmorillonite at higher temperatures brough about the collapse of the interlayers and a decrease in the amount of water sorbed. 相似文献
4.
The thermal dehydration of copper(II) acetate hydrate has been studied between 353 and 406 K, over a range of humidities.
The dehydration is controlled by nucleation-and-growth kinetics at low temperatures, with an activation energy of 154 kJ·mol−1, which changes to contracting-disc kinetics at higher temperatures with a lower activation energy of 76 kJ·mol−1. Frequency factors have also been derived; the value for the high temperature process is low (107s−1) and that for the low temperature step is high (1017s−1). Optical microscopy has been used to clarify the bulk kinetics; there is evidence for a reactive layer at the surface of
the decomposing solid.
In celebration of the 60th birthday of Dr Andrew K. Galwey 相似文献
5.
从芒果皮中提取果胶的工艺研究 总被引:5,自引:0,他引:5
果胶是一种大分子多糖类物质 ,具有良好的胶凝作用 ,用途广泛 ,在国内外市场上的销量很好。 1 990年世界上果胶总产量约 2 5 0 0 0吨 ,而我国 1 990年仅在食品工业上消耗的果胶就达 1 0 0 0吨 ,但国内市场上销售的果胶大部分为进口货[1] 。果胶在我国的生产仍处于开发阶段 ,所以发掘新的提取资源、提高果胶质量、降低果胶生产成本的意义十分重大。目前 ,已有以柑桔皮、向日葵盘、苹果皮、香蕉皮、马铃薯渣为原料提取果胶的研究报道 ,如何从芒果皮中提取果胶却未见报道。芒果在制造罐头和饮料中副产大量下脚料———芒果皮 ,未能得到充分利用… 相似文献
6.
Claudio Arato E. Kendall Pye Gordon Gjennestad 《Applied biochemistry and biotechnology》2005,123(1-3):871-882
Processes that produce only ethanol from lignocellulosics display poor economics. This is generally overcome by constructing
large facilities having satisfactory economies of scale, thus making financing onerous and hindering the development of suitable
technologies. Lignol Innovations has developed a biorefining technology that employs an ethanol-based organosolv step to separate
lignin, hemicellulose components, and extractives from the cellulosic fraction of woody biomass. The resultant cellulosic
fraction is highly susceptible to enzymatic hydrolysis, generating very high yields of glucose (>90% in 12–24h) with typical
enzyme loadings of 10–20 FPU (filter paper units)/g. This glucose is readily converted to ethanol, or possibly other sugar
platform chemicals, either by sequential or simultaneous saccharification and fermentation. The liquor from the organosolv
step is processed by well-established unit operations to recover lignin, furfural, xylose, acetic acid, and a lipophylic extractives
fraction. The process ethanol is recovered and recycled back to the process. The resulting recycled process water is of a
very high quality, low BOD5, and suitable for overall system process closure. Significant benefits can be attained in greenhouse gas (GHG) emission reductions,
as per the Kyoto Protocol. Revenues from the multiple products, particularly the lignin, ethanol and xylose fractions, ensure
excellent economics for the process even in plants as small as 100 mtpd (metric tonnes per day) dry woody biomass input—a
scale suitable for processing wood residues produced by a single large sawmill. 相似文献
7.
The effect of the trace metals Cu, K, Na, and Ca, separately or in mixture, on fermentation time, ethanol production rate,
and cell growth in the fermentation of synthetic media containing sucrose is discussed. The results are related to the range
of contents found in raw materials, molasses and raisins, in order to determine their optimum concentrations for alcohol production. 相似文献
8.
Summary Kinetics of dehydration of equilibrium swollen poly(acrylic acid) hydrogel was investigated using methods of non-isothermal
thermal analysis. Methods of Kissinger, Coats-Redfern, Van Krevelen and Horowitz-Metzger were applied for determination the
kinetics parameters: activation energy (E), pre-exponent (lnA) as well as the kinetics model ƒ(69) for the process of hydrogel dehydration under different heating rates. An existence
of good agreement between determined values of kinetic parameters (Eand A), which were obtained applying different methods under the same heating rate. Functional relationship between changes of
kinetic parameters of dehydration and changes of heating rate was established. An existence of compensation effect is accepted
and explanation of compensation effect appearance during the hydrogel dehydration is suggested. 相似文献
9.
Mauss F. Murat M. Missiaen J. M. Guilhot B. 《Journal of Thermal Analysis and Calorimetry》1996,47(3):799-813
Dehydration of hydrated ammonium alum is a function of physical gaseous pressure. During dehydration, two kinds of partially dehydrated amorphous alum appears. These solids differ in texture and residual water composition. 相似文献
10.
Melek S. Baymak 《Tetrahedron》2007,63(25):5450-5454
Measurement of polarographic limiting currents at equilibria made it possible at pH 3-7 to simultaneously determine concentrations of benzaldehyde, of its hydrazone and of the carbinolamine derivative. The dependence of concentration of carbinolamine at equilibrium on pH indicated presence of its di-, mono-, and unprotonated forms. Acid dissociation constants of the formation (pKa1≈3.2) of the diprotonated form and of the dissociation of the monoprotonated form of carbinolamine (pKa2≈4.7) were estimated. The equilibrium constants of formation (K1) and dehydration (K2) of the carbinolamine intermediate were determined. 相似文献