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411.
Jang Min Park Baek-Rock Oh Jeong-Woo Seo Won-Kyung Hong Anna Yu Jung-Hoon Sohn Chul Ho Kim 《Applied biochemistry and biotechnology》2013,170(8):1807-1814
The concentration of ethanol produced from lignocellulosic biomass should be at least 40 g l?1 [about 5 % (v/v)] to minimize the cost of distillation process. In this study, the conditions for the simultaneous saccharification and fermentation (SSF) at fed-batch mode for the production of ethanol from alkali-pretreated empty palm fruit bunch fibers (EFB) were investigated. Optimal conditions for the production of ethanol were identified as temperature, 30 °C; enzyme loading, 15 filter paper unit g?1 biomass; and yeast (Saccharomyces cerevisiae) loading, 5 g l?1 of dry cell weight. Under these conditions, an economical ethanol concentration was achieved within 17 h, which further increased up to 62.5 g l?1 after 95 h with 70.6 % of the theoretical yield. To our knowledge, this is the first report to evaluate the economic ethanol production from alkali-pretreated EFB in fed-batch SSF using S. cerevisiae. 相似文献
412.
Kim DW Jeong HJ Lim ST Sohn MH Katzenellenbogen JA Chi DY 《The Journal of organic chemistry》2008,73(3):957-962
Although protic solvents are generally not preferred for nucleophilic displacement reactions because of their partial positive charge and hydrogen-bonding capacity that solvate the nucleophile and reduce its reactivity, we recently reported a remarkably beneficial effect of using tertiary alcohols as a reaction media for nucleophilic fluorination with alkali metal fluorides, as well as fluorine-18 radiolabeling with [18F]fluoride ion for the preparation of PET radiopharmaceuticals. In this work, we investigate further the influence of the tert-alcohol reaction medium for nucleophilic fluorination with alkali metal fluorides by studying various interactions among tert-alcohols, the alkali metal fluoride (CsF), and the sulfonyloxy substrate. Factors such as hydrogen bonding between CsF and the tert-alcohol solvent, the formation of a tert-alcohol solvated fluoride, and hydrogen bonding between the sulfonate leaving group and the tert-alcohol appear to contribute to the dramatic increase in the rate of the nucleophilic fluorination reaction in the absence of any kind of catalyst. We found that fluorination of 1-(2-mesyloxyethyl)naphthalene (5) and N-5-bromopentanoyl-3,4-dimethoxyaniline (8) with Bu(4)N(+)F(-) in a tert-alcohol afforded the corresponding fluoro products in much higher yield than obtained by the conventional methods using dipolar aprotic solvents. The protic medium also suppresses formation of byproducts, such as alkenes, ethers, and cyclic adducts. 相似文献
413.
414.
The surfactant effect on the lower critical solution temperature (LCST) of thermosensitive poly(organophosphazenes) with
methoxy-poly(ethylene glycol) and amino acid esters as side groups was examined in terms of molecular interactions between
the polyphosphazenes and surfactants including various anionic, cationic, and nonionic surfactants in aqueous solution. Most
of the anionic and cationic surfactants increased the LCST of the polymers: the LCST increased more sharply with increasing
length and hydrophobicity of the hydrophobic part of the surfactant molecule. The ΔLCSTs (T
0.03M − T
0M), the change in the LCST by addition of 0 and 0.03 M sodium dodecyl sulfate (SDS), were found to be 7.0 and 14.5 °C for the
polymers bearing ethyl esters of glycine and aspartic acid, respectively. The LCST increase of poly(organophosphazene) having
a more hydrophobic aspartic acid ethyl ester was 2 times larger compared with that of the polymer having glycine ethyl ester
as a side group. The binding behavior of SDS to the polymer bearing glycine ethyl ester as a hydrophobic group was explained
from the results of titration of the polymer solutions containing SDS with tetrapropylammonium bromide. Graphic models for
the molecular interactions of polymer/surfactant and polymer/surfactant/salt in aqueous solutions were proposed.
Received: 17 February 2000/Accepted: 25 April 2000 相似文献
415.
We have designed and synthesized new anion receptors 1 and 2, which have amide NH, pyrrole NH and vinyl CH as hydrogen bond donors. These receptors are selective for dimethyl phosphinate and carboxylates. Due to electron withdrawing effect of the cyano group which is trans to the vinyl hydrogen with respect to carbon-carbon double bond, receptor 1 has higher binding constants for phosphinate and carboxylate than those of receptor 2. Modeling studies shows that cyano group polarized all three hydrogens through planar π-electron network. In addition, receptor 1 gave orange colored 1,4-addition product for cyanide. 相似文献
416.
Experimental Mechanics - This paper presents the development of an online stress monitoring technique based on Lamb-wave measurements and a convolutional neural network (CNN) for metallic... 相似文献
417.
Jung-Sun Sohn Soo-Kyung Choi Byung-Wook Jo Michael Hess Manfred Zähres 《Macromolecular Symposia》2003,201(1):163-170
Coupling of a hydrophobic pharmaceutical agents with the hydrophilic poly(ethylene oxide) chain can make the drug water soluble which is necessary for some applications. The modification of the polymer chain results in a different solution behaviour of the macromolecules compared with the unmodified polymer. There are strong indications that shape and rigidity of the modified molecule differ significantly from the simple chain. Some results from measurements of the self-diffusion coefficient and solution viscosity are discussed. The results are important for further engineering on active drug systems. 相似文献