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11.
M.J. Boylan J. Bellerby Josephine Newman A.R. Manning 《Journal of organometallic chemistry》1973,47(2):C33-C35
Whereas Co2(CO)8 and RNC (R= Me, Et, and Cy) react to give mixtures of [(RNC)5Co] [Co(CO)4] and the covalent, carbonyl-bridged [(RNC)mCo2(CO)8?m] derivatives (m = 1–3), [(π-dienyl)Fe(CO)2]2 give only [(π-dienyl)2Fe2(CO)4?n(CNR)n] complexes (dienyl = C5H5, MeC5H4 and C9H7; n = 1–2) that exist in solution as mixtures of cis- and trans-CO- and RNC-bridged tautomers with the μ-RNC species decreasing in importance as the bulk of R increases. 相似文献
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Anthony Manning 《Bulletin of the Brazilian Mathematical Society》1992,22(2):157-177
The trouble with Newton's method for finding the roots of a complex polynomial is knowing where to start the iteration. In this paper we apply the theory of rational maps and some estimates based on distortion theorems for univalent functions to find lower bounds, depending only on the degreed, for the size of regions from which the iteration will certainly converge to a root. We can also bound the number of iterations required and we give a method that works for every polynomial and takes at most some constant timesd
2(logd)2 log(d
3/) iterations to find one root to within an accuracy of . 相似文献
14.
Although very bulky ligands e.g.(o-MeC6H4)3E or (μ-C10H7)3E (E = P or As) are inert, the normal photochemical or thermal reaction of tertiary phosphines or arsines, L, with [Mn2(CO)10] is CO substitution with the formation of [Mn2(CO)8(L)2] derivatives (I). At elevated temperatures some triarylarsines, R3As, undergo Lambert's reaction with ligand fragmentation to give [Mn2(CO)8(μ-AsR2)2] complexes (II) (R = Ph, p-MeOC6H4, p-FC6H4, or p-CIC6H4) even though, in the absence of [Mn2(CO)10] R3As are stable under the same conditions. Exceptional behaviour is exhibited by (p-Me2NC6H4)3- As which forms a product of type I; by some HN(C6H4)2AsR which give a product of type II as a result of loss of the non-aryl groups R = PhCH2, cyclo-C6H11, or MeO; and by Ph(α-C10H72P which is the only phosphine to form a product of type II, albeit in trace amounts only. The thermal decomposition of a n-butanol solution of [Mn2(CO)8(AsPh3)2] in a sealed tube gives C6H6 and [Mn2(CO)8(α-AsPh2)2], whilst in an open system in the presence of various tertiary phosphines, L, [Mn(H)(CO)3(L)2] are obtained. It is suggested that Lambert's reaction is a thermal fragmentation of [Mn(CO)4(AsR3]* radicals, the first to be recognised. They lose the radical R* which abstracts hydrogen from the solvent. The resulting [Mn(CO)4(AsR2)] moiety dimerises to [Mn2(CO)8-(α-AsR2)2]. the reaction is facilitated by the stability of the departing radical (e.g. PhCH2 or MeO) and, as the crowding about As is relieved, by its size (e.g. Ph, cyclo-C6H11, o-MeC6H4, or α-C10H7). In general, phosphine-substituted radicals [Mn(CO)4(PR)3]* do not undergo this decomposition, probably because the PC bonds are much stronger than AsC. 相似文献
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16.
Strong nucleophiles undergo conjugate addition reactions with enolates of Nazarov-type reagents. Yields are strongly affected by substitution patterns and the metal cation employed. 相似文献
17.
Photocatalytic Water Oxidation by a Pyrochlore Oxide upon Irradiation with Visible Light: Rhodium Substitution Into Yttrium Titanate
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Borbala Kiss Dr. Christophe Didier Timothy Johnson Dr. Troy D. Manning Dr. Matthew S. Dyer Dr. Alexander J. Cowan Dr. John B. Claridge Prof. James R. Darwent Prof. Matthew J. Rosseinsky 《Angewandte Chemie (International ed. in English)》2014,53(52):14480-14484
A stable visible‐light‐driven photocatalyst (λ≥450 nm) for water oxidation is reported. Rhodium substitution into the pyrochlore Y2Ti2O7 is demonstrated by monitoring Vegard′s law evolution of the unit‐cell parameters with changing rhodium content, to a maximum content of 3 % dopant. Substitution renders the solid solutions visible‐light active. The overall rate of oxygen evolution is comparable to WO3 but with superior light‐harvesting and surface‐area‐normalized turnover rates, making Y2Ti1.94Rh0.06O7 an excellent candidate for use in a Z‐scheme water‐splitting system. 相似文献
18.
Kosikov KM Gorin AA Lu XJ Olson WK Manning GS 《Journal of the American Chemical Society》2002,124(17):4838-4847
DNA dodecamers of the alternating d(CG).d(CG) sequence with six phosphate groups either charge-neutralized or substituted by neutral methylphosphonates across the major or minor groove have been subjected to energy minimization to determine the conformational effect of the asymmetric elimination of phosphate charge. We report bending angles, directions of bending, and detailed structural characteristics such as groove widths and local base-pair parameters. Our principal results are that charge neutralization on one face of the DNA induces significant bending toward the neutralized face, in agreement with theoretical predictions on a simplified model and experimental data on a similar base-pair sequence, and that the DNA conformation averaged over all stereospecific methylphosphonate substitutions is nearly the same as the conformation produced by charge neutralization of the phosphates. Individual isomers, however, cover a wide range of structures, with the magnitude and direction of overall bending sensitive to the precise stereochemical pattern of neutralization. Our simulation does not explicitly contain counterions, and the results therefore suggest that counterions can influence DNA structure by neutralizing the phosphate charge. These data provide new hints into the molecular mechanisms which underlie the deformations of DNA structure induced by the binding of positively charged proteins and other tightly associated cationic species. 相似文献
19.
R. Manning 《Optical and Quantum Electronics》1971,3(2):93-97
This paper gives a unified theoretical analysis of Laser Doppler systems covering both the optical and electronic aspects, and applicable to all systems which have either a real or virtual fringe pattern. Previous experimental results by Greated for the Doppler spectrum are confirmed and in addition a fuller treatment of the low frequency part of the spectrum is presented. 相似文献
20.