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231.
Neil Burford Paul J Ragogna Katherine N Robertson T Stanley Cameron Ned J Hardman Philip P Power 《Journal of the American Chemical Society》2002,124(3):382-383
Pentaphenylphosphinophosphonium trifluoromethanesulfonate reacts with amino-iminogall(I)ane to effect quantitative substitution of Ph3P and formation of the first complex of a gallium Lewis base on a phosphine Lewis acid. 相似文献
232.
Single-walled carbon nanotubes can exist in chiral forms and can adsorb a range of molecules. We use atomistic simulations to consider whether enantiopure carbon nanotubes might be effective enantiospecific adsorbents for chiral molecules. We examine the adsorption of both enantiomers of trans-1,2-dimethylcyclopropane and trans-1,2-dimethylcyclohexane in a range of chiral nanotubes. Our simulations indicate that these molecules are strongly adsorbed in nanotubes, that is, they have large heats of adsorption, but the energy differences between adsorbed enantiomers are negligible. We argue that this result is generic for chiral organic molecules adsorbed in carbon nanotubes, suggesting that these materials will not be effective enantiospecific adsorbents. 相似文献
233.
Katherine Buggle William K. Glass Michael Nangle Joseph Power 《Monatshefte für Chemie / Chemical Monthly》1982,113(1):81-90
2-(1H-Heteroarylidene)-1H-indene-1,3(2H)-diones were converted into anils and dianils and then into monothio- and dithio-derivatives by treatment with hydrogen sulphide. The 2-pyridinyl monothioderivate was converted into S-alkyl ethers. In contrast with the dione1 the thio-derivatives readily formed isolable complexes with transition metals. Spectroscopic and magnetic data are reported.
Thio-Analoge von 2-(1H-Heteroaryliden)-1H-inden-1,3(2H)-dionen. Synthese und Bildung von Metallkomplexen
Zusammenfassung 2-(1H-Heteroaryliden)-1H-inden-1,3(2 H)-dione wurden in Anile und Dianile und durch anschließende Behandlung mit Schwefelwasserstoff in die entsprechenden Mono- und Di-thio-derivate umgewandelt. Aus den 2-Pyridinyl-monothio-derivaten wurdenS-Alkyl-ether erhalten. Im Gegensatz zum Dion1 bildeten die Thioderivate glatt isolierbare Komplexe mit Übergangsmetallen. Spektroskopische und magnetische Daten werden mitgeteilt.相似文献
234.
The lineshapes of optically detected magnetic resonance (ODMR) spectra from two different, but complementary methods, are predicted using the geometrical model of Breiland and Harris. The ODMR spectra by differential saturation method of van der Velden and Veeman and the pre-saturation pulse technique are examined. Of particular interest are the ODMR spectra for which narrow dips upon a broad background are observed. 相似文献
235.
236.
The thermal degradation reactions of seven aromatic amides which are structurally related to the commercial aramids Kevlar (poly(1,4-phenylene terephthalamide)) and Nomex (poly(1,3-phenylene isophthalamide) have been investigated in the temperature range 450 to 700°C by pyrolysis/gas chromatography/mass spectrometry. Benzanilide, N,N′-dibenzoyl-1,4-phenylenediamine, N,N′-dibenzoyl-1,3-phenylenediamine, N,N′-diphenylterephthalamide, N,N′-diphenylisophthalamide, N-(4-aminophenyl)-benzamide and N-(3-aminophenyl)benzamide all gave very low yields of carbon oxides and water. The structures of the higher molecular weight products were related to those of the parent compounds and their yields are presented quantitatively. The principal mechanism for thermal cleavage of the amide bonds in the N,N′-dibenzoylphenylenediamines is mainly heterolytic, while for the other compounds thermal cleavage of the amide bonds is homolytic. The relationship between the pyrolysis products of the model compounds and those of the corresponding aramids is discussed. 相似文献
237.
Power PP 《Chemical communications (Cambridge, England)》2003,(17):2091-2101
Recent experimental results which have described the characterization of the first, stable heavier group 14 element analogues of acetylenes are outlined. It is shown that the use of large terphenyl substituents allows the isolation of transition metal-heavier group 14 element complexes that can achieve essential triple bonding by a three-fold orbital interaction between the transition metal and group 14 moiety. On the other hand the alkyne analogues RMMR (R = Ge, Sn or Pb) display increasing distortions from linearity to trans-bent geometry due to the accumulation of non-bonding electron density at the group 14 element. The non-bonding electron density comes at the expense of electron density in the bonding region between the group 14 elements. Accordingly the bond orders are decreased to values that are near double for the germanium and tin derivatives and single for the lead compound. 相似文献
238.
Schell D. J. Torget R. Power A. Walter P. J. Grohmann K. Hinman N. D. 《Applied biochemistry and biotechnology》1991,(1):87-97
Lignocellulosic biomass is one of the most plentiful and potentially cheapest feedstocks for ethanol production. The cellulose
component can be broken down into glucose by enzymes and then converted to ethanol by yeast. However, hydrolysis of cellulose
to glucose is difficult, and some form of pretreatment is necessary to increase the susceptibility of cellulose to enzymatic
attack. An analysis has been completed of two pretreatment options, dilute sulfuric acid hydrolysis and sulfur dioxide impregnated
steam explosion, for two feedstocks, wheat straw and aspen wood chips. Detailed process flow sheets and material and energy
balances were used to generate equipment cost information. A technical and economic analysis compared the two feedstocks for
each of the two pretreatments. For the same pretreatment, sugars produced from aspen wood hydrolysis were cheaper because
of the higher carbohydrate content of aspen, whereas dilute acid pretreatment is favored over acid-catalyzed steam explosion. 相似文献
239.
Dr. David J. Liptrot Dr. Jing‐Dong Guo Prof. Shigeru Nagase Prof. Philip P. Power 《Angewandte Chemie (International ed. in English)》2016,55(47):14766-14769
The transition metal tetra‐ and trinorbornyl bromide complexes, M(nor)4 (M=Fe, Co, Ni) and Ni(nor)3Br (nor=1‐bicyclo[2.2.1]hept‐1‐yl) and their homolytic fragmentations were studied computationally using hybrid density functional theory (DFT) at the B3PW91 and B3PW91‐D3 dispersion‐corrected levels. Experimental structures were well replicated; the dispersion correction resulted in shortened M?C bond lengths for the stable complexes, and it was found that Fe(nor)4 receives a remarkable 45.9 kcal mol?1 stabilization from the dispersion effects whereas the tetragonalized Co(nor)4 shows stabilization of 38.3 kcal mol?1. Ni(nor)4 was calculated to be highly tetragonalized with long Ni?C bonds, providing a rationale for its current synthetic inaccessibility. Isodesmic exchange evaluation for Fe(nor)4 confirmed that dispersion force attraction between norbornyl substituents is fundamental to the stability of these species. 相似文献
240.
Wenxing Zou Markus Bursch Kristian L. Mears Cary R. Stennett Ping Yu James C. Fettinger Stefan Grimme Philip P. Power 《Angewandte Chemie (International ed. in English)》2023,62(22):e202301919
Reaction of {LiC6H2−2,4,6-Cyp3⋅Et2O}2 (Cyp=cyclopentyl) ( 1 ) of the new dispersion energy donor (DED) ligand, 2,4,6-triscyclopentylphenyl with SnCl2 afforded a mixture of the distannene {Sn(C6H2−2,4,6-Cyp3)2}2 ( 2 ), and the cyclotristannane {Sn(C6H2−2,4,6-Cyp3)2}3 ( 3 ). 2 is favored in solution at higher temperature (345 K or above) whereas 3 is preferred near 298 K. Van't Hoff analysis revealed the 3 to 2 conversion has a ΔH=33.36 kcal mol−1 and ΔS=0.102 kcal mol−1 K−1, which gives a ΔG300 K=+2.86 kcal mol−1, showing that the conversion of 3 to 2 is an endergonic process. Computational studies show that DED stabilization in 3 is −28.5 kcal mol−1 per {Sn(C6H2−2,4,6-Cyp3)2 unit, which exceeds the DED energy in 2 of −16.3 kcal mol−1 per unit. The data clearly show that dispersion interactions are the main arbiter of the 3 to 2 equilibrium. Both 2 and 3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results). 相似文献