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51.
Dipak Ghosh Argha Deb Subrata Biswas Pasupati Mandal Asok Kumar Mallick Prabir Kumar Haldar 《Indian Journal of Physics》2009,83(10):1463-1485
This paper presents an investigation of compound hadrons (pions and protons) distribution emitted from 24Mg-AgBr and 12C-AgBr interactions both at 4.5 AGeV and 32S-AgBr interactions at 200 AGeV. The study includes azimuthal correlations (two particle and three particle), azimuthal asymmetry
and fractal behaviour. This paper reveals some interesting results. 相似文献
52.
The reactions of dimeric complex [Rh(CO)2Cl]2 with hemilabile ether‐phosphine ligands Ph2P(CH2) nOR [n = 1, R = CH3 (a); n = 2, R = C2H5 (b)] yield cis‐[Rh(CO)2Cl(P ~ O)] (1) [P ~ O = η 1‐(P) coordinated]. Halide abstraction reactions of 1 with AgClO4 produce cis‐[Rh(CO)2(P ∩ O)]ClO4 (2) [P ∩ O = η 2‐(P,O)chelated]. Oxidative addition reactions of 1 with CH3I and I2 give rhodium(III) complexes [Rh(CO)(COCH3)ClI(P ∩ O)] (3) and [Rh(CO)ClI2(P ∩ O)] (4) respectively. The complexes have been characterized by elemental analyses, IR, 1H, 13C and 31P NMR spectroscopy. The catalytic activity of 1 for carbonylation of methanol is higher than that of the well‐known [Rh(CO)2I2]? species. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
53.
Understanding the purchase rates of households for frequently purchased packaged goods is an important element in developing effective marketing strategies. Previous researchers have attempted to estimate these rates by assuming that the time between purchases is a random variable that follows some common parametric probability distribution such as the exponential or Weibull distribution. Recent research has shown that for many frequently purchased packaged goods, the interpurchase times cannot be adequately described by these commonly used probability distributions. In this study we demonstrate how household purchase rates can be estimated in a robust manner using a generalized semiparametric approach that obviates the need for specifying a parametric form for the distribution of interpurchase times. The motivation being that often there is no theory of household purchase behaviour that specifies a priori the probability distribution underlying the interpurchase times. Our empirical results indicate that, for the data analysed, the household purchase rates exhibit a regular pattern that cannot be recovered by probability distributions often used in previous research. Further, marketing actions taken by sellers do indeed influence household purchase behaviour. 相似文献
54.
Aditya Mishra Dipak K. Dey Kun Chen 《Journal of computational and graphical statistics》2017,26(4):814-825
In multivariate regression models, a sparse singular value decomposition of the regression component matrix is appealing for reducing dimensionality and facilitating interpretation. However, the recovery of such a decomposition remains very challenging, largely due to the simultaneous presence of orthogonality constraints and co-sparsity regularization. By delving into the underlying statistical data-generation mechanism, we reformulate the problem as a supervised co-sparse factor analysis, and develop an efficient computational procedure, named sequential factor extraction via co-sparse unit-rank estimation (SeCURE), that completely bypasses the orthogonality requirements. At each step, the problem reduces to a sparse multivariate regression with a unit-rank constraint. Nicely, each sequentially extracted sparse and unit-rank coefficient matrix automatically leads to co-sparsity in its pair of singular vectors. Each latent factor is thus a sparse linear combination of the predictors and may influence only a subset of responses. The proposed algorithm is guaranteed to converge, and it ensures efficient computation even with incomplete data and/or when enforcing exact orthogonality is desired. Our estimators enjoy the oracle properties asymptotically; a non-asymptotic error bound further reveals some interesting finite-sample behaviors of the estimators. The efficacy of SeCURE is demonstrated by simulation studies and two applications in genetics. Supplementary materials for this article are available online. 相似文献
55.
JPC – Journal of Planar Chromatography – Modern TLC - A simple, precise, and accurate high-performance thin-layer chromatography (HPTLC) method for the simultaneous determination of... 相似文献
56.
Shanmugaraju S Samanta D Gole B Mukherjee PS 《Dalton transactions (Cambridge, England : 2003)》2011,40(45):12333-12341
Synthesis of a series of two-dimensional metallamacrocycles via coordination-driven self-assembly of a shape-selective Pt(II)(2)-molecular building unit incorporating carbazole-ethynyl functionality is described. An equimolar (1?:?1) combination of a Pt(II)(2)-organometallic 90° acceptor, 1, with rigid linear ditopic donors (L(a) and L(b)) afforded [4 + 4] self-assembled octanuclear molecular squares, 2 and 3, in quantitative yields, respectively [L(a) = 4,4'-bipyridine; L(b) = trans-1,2-bis(4-pyridyl)ethylene]. Conversely, a similar treatment of 1 with an amide-based unsymmetrical flexible ditopic donor, L(c), resulted in the formation of a [2 + 2] self-sorted molecular rhomboid (4a) as a single product [L(c) = N-(4-pyridyl)isonicotinamide]. Despite the possibility of several linkage isomeric macrocycles (rhomboid, triangle and square) due to the different connectivity of L(c), the formation of a single and symmetrical molecular rhomboid (4a) as the only product is an interesting observation. All the self-assembled macrocycles (2, 3 and 4a) were fully characterized by multinuclear NMR ((1)H and (31)P) and ESI-MS analysis. Further structural insights about the size and shape of the macrocycles were obtained through energy minimization using density functional theory (DFT) calculations. Decoration of the starting carbazole building unit with Pt-ethynyl functionality enriches the assemblies to be more π-electron rich and luminescent in nature. Macrocycles 2 and 3 could sense the presence of electron deficient nitroaromatics in solution by quenching of the initial intensity upon gradual addition of picric acid (PA). They exhibited the largest quenching response with high selectivity for nitroaromatics compared to several other electron deficient aromatics tested. 相似文献
57.
58.
Dipak Prajapati Dhrubojyoti D. LaskarBaikuntha J. Gogoi Gitali Devi 《Tetrahedron letters》2003,44(35):6755-6757
The indium-catalysed coupling of propargyl bromide with a variety of imines and imine oxides afforded the corresponding propargylated products in high yields under mild conditions. 相似文献
59.
Dipak Ghosh Argha Deb Swarnapratim Bhattacharyya Jayita Ghosh Rupa Das 《Acta Physica Hungarica A》2003,17(1):161-166
This paper reports an investigation on the two-particle long-range angular correlation among the target fragments produced in 28Si–AgBr interactions at 14.5 AGeV, 16O–AgBr interactions at 60 AGeV and 32S–AgBr interactions at 200 AGeV. The experimental data have been compared with Monte Carlo simulated events to extract dynamical correlation. The data exhibit two-particle long-range correlation in emission angle space at all energies. 相似文献
60.
Dimeric chlorobridge complex [Rh(CO)2Cl]2 reacts with two equivalents of a series of unsymmetrical phosphine–phosphine monoselenide ligands, Ph2P(CH2)nP(Se)Ph2 {n = 1( a ), 2( b ), 3( c ), 4( d )}to form chelate complex [Rh(CO)Cl(P∩Se)] ( 1a ) {P∩Se = η2‐(P,Se) coordinated} and non‐chelate complexes [Rh(CO)2Cl(P~Se)] ( 1b–d ) {P~Se = η1‐(P) coordinated}. The complexes 1 undergo oxidative addition reactions with different electrophiles such as CH3I, C2H5I, C6H5CH2Cl and I2 to produce Rh(III) complexes of the type [Rh(COR)ClX(P∩Se)] {where R = ? C2H5 ( 2a ), X = I; R = ? CH2C6H5 ( 3a ), X = Cl}, [Rh(CO)ClI2(P∩Se)] ( 4a ), [Rh(CO)(COCH3)ClI(P~Se)] ( 5b–d ), [Rh(CO)(COH5)ClI‐(P~Se)] ( 6b–d ), [Rh(CO)(COCH2C6H5)Cl2(P~Se)] ( 7b–d ) and [Rh(CO)ClI2(P~Se)] ( 8b–d ). The kinetic study of the oxidative addition (OA) reactions of the complexes 1 with CH3I and C2H5I reveals a single stage kinetics. The rate of OA of the complexes varies with the length of the ligand backbone and follows the order 1a > 1b > 1c > 1d . The CH3I reacts with the different complexes at a rate 10–100 times faster than the C2H5I. The catalytic activity of complexes 1b–d for carbonylation of methanol is evaluated and a higher turnover number (TON) is obtained compared with that of the well‐known commercial species [Rh(CO)2I2]?. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献