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排序方式: 共有93条查询结果,搜索用时 187 毫秒
41.
42.
M. L. Cherry A. Da̧browska P. Deines-Jones A. J. Dubinina R. Hołyński W. V. Jones A. Olszewski K. Sengupta V. A. Smirnitski M. Szarska A. Trzupek C. J. Waddington J. P. Wefel B. Wilczynska H. Wilczynski W. Wolter B. Wosiek K. Woźniak 《Zeitschrift fur Physik C Particles and Fields》1997,73(3):449-454
The transverse momentum (pt) distributions of helium fragments from gold fragmentation on different nuclei of nuclear emulsion have been measured and a clear increase of average p t with target mass is seen. The p t distributions can be parameterized by a sum of three exponential functions of the form $\sim {\rm exp}(-p_{t}^{2}/B_{i})$ . The differences in p t distributions in interactions on different targets can be explained by different contributions of the three exponential functions. These contributions depend on the projectile breakup in the collision, and for a given degree of the projectile breakup do not depend on the target mass. 相似文献
43.
Triolo A Russina O Caminiti R Shirota H Lee HY Santos CS Murthy NS Castner EW 《Chemical communications (Cambridge, England)》2012,48(41):4959-4961
X-ray scattering data from four pairs of ionic liquids (ILs) are compared. The alkyl-substituted cations show a first sharp diffraction peak between 3 and 4 nm(-1) that is not observed for ILs having cations with ether- or hydroxy-substitutions. These observations indicate a significant difference in the intermediate range order for these liquids. 相似文献
44.
45.
A convergent synthesis of benzoquinone ansamycin analogs is described that proceeds by a sequence of metallacycle-mediated alkyne-alkyne coupling, followed by site- and stereoselective dihydroxylation and global carbamate formation. These studies have led to (1) validation of alkyne-alkyne coupling to produce geldanamycin analogs that lack the problematic quinone, (2) the discovery that C6-C7 bis-carbamate functionality is compatible with Hsp90 inhibition, and (3) the identification of 1 as a nonquinone geldanamycin-inspired paralog-selective Hsp90 inhibitor. 相似文献
46.
We report the structure functions obtained from x-ray scattering experiments on a series of four homologous ionic liquids. The ionic liquids are 1-alkyl-1-methylpyrrolidinium cations paired with the bis(trifluoromethylsulfonyl)amide anion, with alkyl chain lengths of n = 4, 6, 8, and 10. The structure functions display two intense diffraction peaks for values of the scattering vector q in the range from 0.6 to 1.5 ?(-1) for all samples. Both diffraction peaks shift to lower values of q for increasing temperature. First sharp diffraction peaks are observed in the structure functions for q < 0.5 ?(-1) for liquids with n = 6, 8, and 10. 相似文献
47.
The heart includes a specialized conduction system that ensures the necessary activation sequence and timing of the ventricles
to produce an effective contraction. The role of this system, called the Purkinje network, during ventricular tachyarrhythmias
remains unclear. To understand how the Purkinje network interacts with ventricular muscle, we develop the first combined electrophysiology-structural
model of the canine Purkinje network based on microelectrode recordings and a digitized reconstruction of the Purkinje system.
For the Purkinje electrophysiology model, we construct a new model of canine Purkinje electrophysiology based on action potentials
recorded from canine tissue and designed to reproduce the important phenomenon of alternans. In addition, we use digital photographs
of canine ventricular endocardium stained with Lugol’s solution to develop a structural model of the Purkinje network. We
combine these electrophysiological and anatomical models of the Purkinje system with a model of canine ventricular electrophysiology
to study how the Purkinje network can interact with the ventricular muscle during arrhythmias. Using our combined model, we
find that two different results can occur: The long-range connections provided by the Purkinje network can depolarize the
tissue more quickly, thereby promoting arrhythmia termination, but if termination does not occur, the Purkinje system can
increase the dispersion of refractoriness in the tissue, thereby sustaining the arrhythmia. The different behaviors result
from the two competing effects contributed by the Purkinje network: effective reduction in tissue size and increased spatial
heterogeneity. 相似文献
48.
Microbubbles used as contrast agents for ultrasound imaging, vectors for targeted drug delivery and vehicles for metabolic gas transport require better size control for improved performance. Mechanical agitation is the only method currently available to produce microbubbles in sufficient yields for biomedical applications, but the emulsions tend to be polydisperse. Herein, we describe a study to generate lipid-coated, perfluorobutane-filled microbubbles and isolate their size fractions based on migration in a centrifugal field. Polydispersity of the freshly sonicated suspension was characterized by particle sizing and counting through light obscuration/scattering and electrical impedance sensing, fluorescence and bright-field microscopy and flow cytometry. We found that the size distribution was multimodal. Smaller microbubbles were more abundant. Differential centrifugation was used to successfully isolate the 1-2 and 4-5 mum diameter fractions. Isolated microbubbles were stable over two days. After two weeks, however, more dilute suspensions (<1 vol%) were susceptible to Ostwald ripening. For example, 4-5 mum microbubbles disintegrated into 1-2 mum microbubbles. This latter observation indicated the existence of an optimally stable diameter in the 1-2 mum range for these lipid-coated microbubbles. Overall, differential centrifugation provided a rapid and robust means for size selection and reduced polydispersity of lipid-coated microbubbles. 相似文献
49.
Maestro P. Adriani O. Akaike Y. Asaoka Y. Berti E. Bigongiari G. Bongi M. Brogi P. Bruno A. Cannady N. Checchia C. Cherry M. L. Collazuol G. Guzik T. G. Ichimura M. Israel M. H. Kasahara K. Kawakubo Y. Krizmanic J. F. Marrocchesi P. S. Messineo A. M. Mitchell J. W. Miyake S. Mori M. Mori N. Motz H. M. Munakata K. Pacini L. Palma F. Papini P. Rauch B. F. Ricciarini S. B. Sakamoto T. Sasaki M. Stolzi F. Sulaj A. Tamura T. Torii S. Wefel J. P. Yoshida K. 《Physics of Atomic Nuclei》2019,82(6):766-772
Physics of Atomic Nuclei - The CALorimetric Electron Telescope (CALET) is an astroparticle physics experiment installed on the International Space Station since August 2015. The CALET mission was... 相似文献
50.
Geometrical characterization techniques for microlens made by thermal reflow of photoresist cylinder
Mohammed Ashraf Cherry Gupta Franck Chollet Stuart Victor Springham Rajdeep Singh Rawat 《Optics and Lasers in Engineering》2008,46(10):711-720
Microlens characterization is a prerequisite for improving fabrication process, and for satisfying the end user needs. In this paper we explore techniques to characterize geometrical properties of microlens made by thermal reflow: viz. microlens profile; radius of curvature; microlens height; contact angle and focal length. The geometrical characterization is done using techniques such as contact profilometry, scanning electron microscopy (SEM), optical microscopy, white light confocal microscopy and fluorescence confocal microscopy. All the above techniques are studied and compared, keeping in mind the characterization requirements of polymer microlens made by thermal reflow technique. 相似文献