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83.
This paper uses dynamic programming to investigate when contestants should use lifelines or when they should just stop answering in the TV quiz show ‘Who wants to be a millionaire?’. It obtains the optimal strategies to maximize the expected reward and to maximize the probability of winning a given amount of money. 相似文献
84.
Andrs F. Ypes Alirio Palma Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(3):o123-o125
The molecules of the title compound, C20H15BrClNO, are linked into chains by a C—H...π(arene) hydrogen bond, in which the acceptor is the brominated ring of the naphthalene unit, and these chains are linked by an aromatic π–π stacking interaction, again involving the naphthalene unit, into a sheet structure. 相似文献
85.
Sandra L. Gmez Alirio Palma Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(4):o233-o240
(2SR,4RS)‐2‐exo‐Phenyl‐2,3,4,5‐tetrahydro‐1H‐1,4‐epoxy‐1‐benzazepine, C16H15NO, (I), (2SR,4RS)‐2‐exo‐(4‐chlorophenyl)‐2,3,4,5‐tetrahydro‐1H‐1,4‐epoxy‐1‐benzazepine, C16H14ClNO, (II), and (2SR,4RS)‐2‐exo‐(3‐methylphenyl)‐2,3,4,5‐tetrahydro‐1H‐1,4‐epoxy‐1‐benzazepine, C17H17NO, (III), all crystallize with Z′ = 2, in the space groups Cc, P21/n and P21/c, respectively. In each of (II) and (III), the conformations of the two independent molecules are significantly different. The molecules in (I) are linked by C—H...π(arene) hydrogen bonds to form two independent chains, each containing only one type of molecule. The molecules in (II) are linked into sheets by a combination of C—H...O, C—H...(N,O) and C—H...π(arene) hydrogen bonds, all of which link pairs of molecules related by inversion, while in (III), the molecules are linked into sheets by a combination of C—H...N, C—H...O and C—H...π(arene) hydrogen bonds. There are no direction‐specific intermolecular interactions of any kind in the structure of (2SR,4RS)‐7‐bromo‐2‐exo‐phenyl‐2,3,4,5‐tetrahydro‐1H‐1,4‐epoxy‐1‐benzazepine, C16H14BrNO, (IV), but in the structure of (2SR,4RS)‐2‐exo‐(4‐bromophenyl)‐7‐chloro‐2,3,4,5‐tetrahydro‐1H‐1,4‐epoxy‐1‐benzazepine, C16H13BrClNO, (V), a combination of one C—H...N hydrogen bond and one C—H...O hydrogen bond links the molecules into sheets of alternating centrosymmetric R22(14) and R66(22) rings. Comparisons are made with the structures of a number of related compounds. 相似文献
86.
D. Martínez-Martínez C. López-Cartes A. Justo A. Fernández J.C. Sánchez-López 《Solid State Sciences》2009,11(3):660-670
This paper is devoted to the development of Ti(C,N)-based nanocomposite protective coatings consisting of nanocrystals of a hard phase (TiN or TiCxNy) embedded in an amorphous carbon-based matrix (a-C or a-CNx). The objective here is the achievement of a good compromise between the mechanical and tribological properties by the appropriate control of the hard/soft phase ratio and the microstructural characteristics of the film. To achieve this purpose, dual magnetron sputtering technique was employed following two different strategies. In the first one, we use Ti and graphite targets and Ar/N2 gas mixtures, while in the second case, TiN and graphite targets are sputtered in an Ar atmosphere. By changing the sputtering power applied to each magnetron, different sets of samples are prepared for each route. The effect of the bias voltage applied to the substrate is also studied in some selected cases. The mechanical and tribological properties of the films are characterized and correlated with the microstructure, crystallinity and phase composition. The establishment of correlations enables the development of advanced coatings with tailored mechanical and tribological properties for desired applications. 相似文献
87.
Debora Cobo Jairo Quiroga Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(9):o444-o446
The title compound, C14H11NS, crystallizes with Z′ = 0.75 in the space group C2/m. Two independent molecules are present, one of which lies with all the non‐H atoms on a mirror plane, while the other is fourfold disordered across a site of 2/m symmetry. The ordered molecules are stacked such that they enclose continuous channels running along twofold rotation axes, and the disordered molecules are positioned within these channels. 相似文献
88.
Juan C. Castillo Rodrigo Abonía Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(8):o423-o430
7‐Benzyl‐3‐tert‐butyl‐1‐phenyl‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C22H25N3O, (I), and 3‐tert‐butyl‐7‐(4‐methylbenzyl)‐1‐phenyl‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C23H27N3O, (II), are isomorphous in the space group P21, and molecules are linked into chains by C—H...O hydrogen bonds. In each of 3‐tert‐butyl‐7‐(4‐methoxybenzyl)‐1‐phenyl‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C23H27N3O2, (III), which has cell dimensions rather similar to those of (I) and (II), also in P21, and 3‐tert‐butyl‐1‐phenyl‐7‐[4‐(trifluoromethyl)benzyl]‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C23H24F3N3O, (IV), there are no direction‐specific interactions between the molecules. In 3‐tert‐butyl‐7‐(4‐nitrobenzyl)‐1‐phenyl‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C22H24N4O3, (V), a combination of C—H...O and C—H...N hydrogen bonds links the molecules into complex sheets. There are no direction‐specific interactions between the molecules of 3‐tert‐butyl‐7‐(2,3‐dimethoxybenzyl)‐1‐phenyl‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C24H29N3O3, (VI), but a three‐dimensional framework is formed in 3‐tert‐butyl‐7‐(3,4‐methylenedioxybenzyl)‐1‐phenyl‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C23H25N3O3, (VII), by a combination of C—H...O, C—H...N and C—H...π(arene) hydrogen bonds, while a combination of C—H...O and C—H...π(arene) hydrogen bonds links the molecules of 3‐tert‐butyl‐1‐phenyl‐7‐(3,4,5‐trimethoxybenzyl)‐6,7‐dihydro‐1H,4H‐pyrazolo[3,4‐d][1,3]oxazine, C25H31N3O4, (VIII), into complex sheets. In each compound, the oxazine ring adopts a half‐chair conformation, while the orientations of the pendent phenyl and tert‐butyl substituents relative to the pyrazolo[3,4‐d]oxazine unit are all very similar. 相似文献
89.
This paper deals with the problem of locating path-shaped facilities of unrestricted length on networks. We consider as objective functions measures conceptually related to the variability of the distribution of the distances from the demand points to a facility. We study the following problems: locating a path which minimizes the range, that is, the difference between the maximum and the minimum distance from the vertices of the network to a facility, and locating a path which minimizes a convex combination of the maximum and the minimum distance from the vertices of the network to a facility, also known in decision theory as the Hurwicz criterion. We show that these problems are NP-hard on general networks. For the discrete versions of these problems on trees, we provide a linear time algorithm for each objective function, and we show how our analysis can be extended also to the continuous case. 相似文献
90.
We present a methodology with which to evaluate translations and rotations of wavefront aberration measurements of systems in which the exit pupil suffers displacements and rotations with respect to the reference frame of the measuring device. We propose to use image registration techniques to account for rotations, translations, and scale changes of the pupil. We present a proof of principle, using an artificial eye in addition to computer simulations. The method is software based and requires no additional hardware. 相似文献