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51.
由于非水溶剂的应用日趋广泛,促使物理化学工作者对于溶剂和溶液性质进行研究,同时开展了有关物理化学数据的测定和积累工作,以利于指导实践[1]。目前文献报道含水混合溶剂中的电解质活度系数较多,但非水混合溶剂中电解质活度系数报道较少。电解质浓溶液活度系数的计算方法目前应用较广的是Pitzer半经验算法[2]。Pitzer的算法中具体物系的β(0)、β(1)等系数需从实测活度系数数据拟合求得。孙仁义等通过测定汽液平衡盐效应的方法研究了盐在混合溶剂中的活度系数[3-4]。最近孙仁义等[5]提出了双液比固定条件下含盐体系汽液平衡数据热力学一… 相似文献
52.
The dependent relation between temperature and pressure of supercritical CO2+ ethanol binary system under the pressure range from 5 to 10 MPa with the variety of densities and mole fractions of ethanol
that range from 0 to 2% was investigated by the static visual method in a constant volume. The critical temperature and pressure
were experimentally determined simultaneously. The PTρ figures at different ethanol contents were described based on the determined pressure and temperature data, from which pressure
of supercritical CO2 + ethanol binary system was found to increase linearly with the increasing temperature. P-T lines show certain convergent feature in a specific concentration of ethanol and the convergent points shift to the region
of higher temperature and pressure with the increasing ethanol compositions. Furthermore, the effect of density and ethanol
concentration on the critical point of CO2 + ethanol binary system was discussed in details. Critical points increase linearly with the increasing mole fraction of
ethanol in specific density and critical points change at different densities. The critical compressibility factors Zc of supercritical CO2 + ethanol binary systems at different compositions of ethanol were calculated and Z
c
-ρ figure was obtained accordingly. It was found from Z
c
-ρ figure that critical compressibility factors of supercritical CO2 unitary or binary systems decline linearly with the increasing density, by which the critical point can be predicted precisely. 相似文献
53.
Chen Chee-Shan Chan E. Wang S. L. Gong C. S. Chen L. F. 《Applied biochemistry and biotechnology》1994,(1):531-544
A self-aggregating strain ofSaccharomyces uvarum (U4) was used as a biocatalyst to carry out continuous ethanol fermentation in a tower fermentor equipped with a cell separator.
Cell aggregates (2–3 mm) formed a stable packed bed in the fermentor, and the cell separator retained yeast cells effectively.
Corn steep liquor was used as a nitrogen source for the fermentation of corn syrup and black strap molasses. An ethanol productivity
of 54 g/L/h was reached using corn syrup at a dilution rate of 0.7/h, and sugar concentration in the feed was 15% (w/v). For
molasses fermentation, an ethanol productivity of 22 g/L/h was obtained at a dilution rate of 0.7/h, and sugar concentration
in the feed was 12.5% (w/v). Ethanol yields obtained from tower fermentation are higher than those obtained from flask fermentation
(96% for corn syrup fermentation and 92% for molasses fermentation). No significant loss in fermentation activity was observed
after 3 mo of operation. 相似文献
54.
Schmidt Sherry L. Myers Michele D. Kelley Stephen S. McMillan James D. Padukone Nandan 《Applied biochemistry and biotechnology》1997,(1):469-482
The use of membrane processes for the recovery of fermentation products has been gaining increased acceptance in recent years.
Pervaporation has been studied in the past as a process for simultaneous fermentation and recovery of volatile products such
as ethanol and butanol. However, membrane fouling and low permeate fluxes have imposed limitations on the effectiveness of
the process. In this study, we characterize the performance of a substituted polyacetylene membrane, poly[(l-trimethylsilyl)-l-propyne]
(PTMSP), in the recovery of ethanol from aqueous mixtures and fermentation broths. Pervaporation using PTMSP membranes shows
a distinct advantage over conventional poly(dimethyl siloxane) (PDMS) membranes in ethanol removal. The flux with PTMSP is
about threefold higher and the concentration factor is about twofold higher than the corresponding performance achieved with
PDMS under similar conditions. The performance of PTMSP with fermentation broths shows a reduction in both flux and concentration
factor relative to ethanol-water mixtures. However, the PTMSP membranes indicate initial promise of increased fouling resistance
in operation with cell-containing fermentation broths. 相似文献
55.
Synthesis, Structure and Conductivity of the New Charge-transfer Salt (ET)_2(CH_2=CH-CH_2-SO_3)·H_2O
Zhi LIU Qi FANG* Wen Tao YU Min Hua JIANG De Qing ZHANG Dao Ben ZHU State Key Laboratory of Crystal Materials Shandong University Jinan Institute of Chemistry The Chinese Academy of Sciences Beijing 《中国化学快报》2003,14(4)
ET is one of the most famous electron-donor molecules, which forms charge-transfer complexes (abbr. CT-complexes) with various types of counterions. These complexes have received intense attention because a wide range of physical properties such as conductivity and superconductivity1, ferromagnetism2-4 and nonlinear optical properties5 was found in these materials. Although the majority of the ET-based CT-complexes were prepared by combining with inorganic counterions, CT-complexes with o… 相似文献
56.
I. S. Kislina M. Yu. Kulikova S. G. Sysoeva O. N. Temkin 《Russian Chemical Bulletin》1994,43(10):1626-1629
The acidity functionsH
0
s of HCl solutions in EtOH-H2O solvents containing 1.09, 3.0, and 5.0% water have been measured at 25 and 40 °C by the indicator method. The concentration of HCl changes from 10–2 to 36m. Nitroanilines, for which a protonation mechanism is realized in the studied systems, were used as indicators.For each solvent,H
0
s is temperature independent atm
HCl < 4, and acidity atm
HCl > 4 mol L–1 increases more rapidly at 25 °C than at 40 °C. The acidity functions of aqueous and water-ethanol solutions of HCl were compared, and the concentrations of proton solvates of different compositions and their relative protonating ability were evaluated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1722–1725, October, 1994.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-18356). 相似文献
57.
Nguyen Q. A. Tucker M. P. Boynton B. L. Keller F. A. Schell D. J. 《Applied biochemistry and biotechnology》1998,(1):77-87
Selective thinning of forests in the western United States will generate a large, sustainable quantity of softwood residues
that can be an attractive feedstock for fuel ethanol production. The major species available from thinning of forests in northern
California and the eastern Rocky Mountains include white fir (Abies concolor), Douglas fir (Pseudotsuga menziesii), and Ponderosa pine (Pinus ponderosa). Douglas fir chips were soaked in 0.4% sulfuric acid solution, then pretreated with steam at 200 – 230°C for 1 – 5 min.
After pretreatment, 90 – 95% of the hemicellulose and as much as 20% of the cellulose was solubilized in water, and 90% of
the remaining cellulose can be hydrolyzed to glucose by cellulase enzyme. The prehydrolysates, at as high as 10% total solid
concentration, can be readily fermented by the unadapted yeastSaccharomyces cerevisiae D5A. 相似文献
58.
The enthalpies of transfer of 2-methyl-2-propanol (TBA) from water to mixtures of water with methanol, ethanol and 1,4-dioxane
have been measured. The data are considered in terms of recently developed theory, and it is found that the enthalpies of
transfer can be reproduced quantitatively over most of the composition range in each solvent system. The parameters recovered
from the analyses indicate that the net effect of TBA on the solvent structure is a breaking of solvent-solvent bonds and
that TBA is preferentially hydrated in the aqueous alcohol systems, but randomly solvated in the water+1,4-dioxane system.
It is also found that the model parameters for TBA solvation in the alcohol systems are independent of the alcohol. 相似文献
59.
Mohamed Ahmed Khaireh Marie Angot Clara Cilindre Grard Liger-Belair David A. Bonhommeau 《Molecules (Basel, Switzerland)》2021,26(6)
The diffusion of carbon dioxide (CO) and ethanol (EtOH) is a fundamental transport process behind the formation and growth of CO bubbles in sparkling beverages and the release of organoleptic compounds at the liquid free surface. In the present study, CO and EtOH diffusion coefficients are computed from molecular dynamics (MD) simulations and compared with experimental values derived from the Stokes-Einstein (SE) relation on the basis of viscometry experiments and hydrodynamic radii deduced from former nuclear magnetic resonance (NMR) measurements. These diffusion coefficients steadily increase with temperature and decrease as the concentration of ethanol rises. The agreement between theory and experiment is suitable for CO. Theoretical EtOH diffusion coefficients tend to overestimate slightly experimental values, although the agreement can be improved by changing the hydrodynamic radius used to evaluate experimental diffusion coefficients. This apparent disagreement should not rely on limitations of the MD simulations nor on the approximations made to evaluate theoretical diffusion coefficients. Improvement of the molecular models, as well as additional NMR measurements on sparkling beverages at several temperatures and ethanol concentrations, would help solve this issue. 相似文献
60.
Ethanol determination in frozen fruit pulps: an application of quantitative nuclear magnetic resonance 下载免费PDF全文
Wilian da Silva Nunes Caroline Silva de Oliveira Glaucia Braz Alcantara 《Magnetic resonance in chemistry : MRC》2016,54(4):334-340
This study reports the chemical composition of five types of industrial frozen fruit pulps (acerola, cashew, grape, passion fruit and pineapple fruit pulps) and compares them with homemade pulps at two different stages of ripening. The fruit pulps were characterized by analyzing their metabolic profiles and determining their ethanol content using quantitative Nuclear Magnetic Resonance (qNMR). In addition, principal component analysis (PCA) was applied to extract more information from the NMR data. We detected ethanol in all industrial and homemade pulps; and acetic acid in cashew, grape and passion fruit industrial and homemade pulps. The ethanol content in some industrial pulps is above the level recommended by regulatory agencies and is near the levels of some post‐ripened homemade pulps. This study demonstrates that qNMR can be used to rapidly detect ethanol content in frozen fruit pulps and food derivatives. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献