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41.
The effects of furan and maleimide substitution on the dynamic reversibility of their Diels-Alder reactivity have been investigated computationally and by (1)H NMR spectroscopy. Furan and furan derivatives bearing methoxy, methyl, or formyl groups at their 2- or 3-positions were investigated with maleimide and maleimide derivatives bearing N-methyl, N-allyl, and N-phenyl substituents. Computational predictions indicate that electronic and regiochemical effects of furan substitution significantly influence their Diels-Alder reactivity with maleimide, with reaction free energies of exo adduct formation ranging from ΔG = -9.4 to 0.9 kcal/mol and transition state barriers to exo adduct formation ranging from ΔG(?) = 18.9 to 25.6 kcal/mol. Much less variation was observed for the reactivity of N-substituted maleimide derivatives and furan, with reaction and transition state free energies each falling within a range of 1.1 kcal/mol. Dynamic exchange experiments monitored by (1)H NMR spectroscopy support computational predictions. The results indicate the reactivity and reversibility of furan-maleimide cycloadditions can be tuned significantly through the addition of appropriate substituents and have implications in the use of furan and maleimide derivatives in the construction of thermally responsive organic materials. 相似文献
42.
Moussa Dicko Christophe Coquelet Carmen Jarne Scott Northrop Dominique Richon 《Fluid Phase Equilibria》2010
Aqueous amine solutions are widely used in the industry for acid gas removal. In order to treat natural gas or refinery process streams, an accurate knowledge of solubility data of carbon dioxide, hydrogen sulfide and other sulfur species in aqueous amine solutions is required. In this paper, new equilibrium measurements on 50 wt% aqueous methyldiethanolamine solution with CO2 and H2S have been produced. A simple way to correlate the data has been searched and found. First, a model proposed by Posey et al. in 1996, then a Deshmukh–Mather model are used to correlate “vapor–liquid” equilibria. The Posey et al. model lacks accuracy to represent the experimental data, especially for high loadings. The Deshmukh–Mather model shows good agreement as long as the total loading (H2S + CO2) does not reach 1.0. 相似文献
43.
Li SS Yan HJ Wan LJ Yang HB Northrop BH Stang PJ 《Journal of the American Chemical Society》2007,129(30):9268-9269
44.
电感耦合等离子体原子发射光谱法测定马奶酒中的多种元素 总被引:2,自引:0,他引:2
电感耦合等离子体原子发射光谱法测定马奶酒中的多种元素嘎日迪,乌地(内蒙古师范大学化学系,配位化学研究所,呼和浩特,010022)关键词电感耦合等离子体原子发射光谱,马奶酒,微量金属元素蒙古民族喜爱的传统饮料──马奶酒(蒙语“策格”)是用鲜马奶为原料发... 相似文献
45.
46.
R. Cambier L. Leroux D. I. Hitchcock Ruth C. Belden und J. H. Northrop 《Fresenius' Journal of Analytical Chemistry》1936,106(7-8):300-301
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48.
基于结构方程(SEM)理论,以2008年统计数据为样本对影响城市现代化的测量指标进行了一阶、二阶验证性因素分析,得到了结构方程模型.并以测量指标在因子上的负荷、路径系数为基础构建权重,建立了城市现代化水平综合评价模型.对我国重要城市(直辖市、主要省会城市)现代化水平程度进行了相对评价,得到较为满意的结果. 相似文献
49.
[reaction: see text] Mixing of equimolar amounts of cyclobis(paraquat-p-phenylene) (CBPQT(4+)) with a bis-4-methylphenyl ether (MPE twice) of a 1,5-dioxynaphthalene (DNP) derivative in MeCN/CH(2)Cl(2) (3:1) results in the formation of a [2]pseudorotaxane which, on crystallization, yields a [4]pseudorotaxane in the solid state that is stabilized by multiple [C-H...F] interactions: a mixture of the same components in a 1:3 ratio affords a crystalline [2]pseudorotaxane after vapor diffusion of methyl-tert-butyl ether into a solution of these components in MeCN/CH(2)Cl(2) (3:1). 相似文献
50.
Allyl‐Functionalized Dioxynaphthalene[38]Crown‐10 Macrocycles: Synthesis,Self‐Assembly,and Thiol‐ene Functionalization
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Umesh Choudhary Prof. Brian H. Northrop 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(4):999-1009
Five dioxynaphthalene[38]‐crown‐10 ( DNP38C10 ) macrocycles bearing one, two, three, or four allyl moieties have been synthesized and their ability to spontaneously self‐assemble with methyl viologen to form [2]pseudorotaxanes has been evaluated. Association constants between methyl viologen and several of the allyl‐functionalized DNP38C10 macrocycles are found to be comparable to that of methyl viologen and unfunctionalized DNP38C10 , however, the enthalpic and entropic factors that underlie overall binding free energy vary systematically with increasing allyl substitution. These variations are explained through a combination of solution phase and solid‐state analysis of the macrocycles and their complexes. The utility of endowing DNP38C10 macrocycles with allyl moieties is further demonstrated by the ease with which they can be functionalized through thiol‐ene click chemistry. 相似文献