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41.
Sue Gifford 《Research in Mathematics Education》2013,15(3):219-233
This article sets out to evaluate the English Early Years Foundation Stage Goal for Numbers, in relation to research evidence. The Goal, which sets out to provide ‘a good foundation in mathematics’, has greater breadth of content and higher levels of difficulty than previous versions. Research suggests that the additional expectations are unachievable by the majority of rising fives, but that a more effective foundation to ensure progress and prevent later difficulties would prioritise number sense with numbers to 10, including subitising, numeral comprehension, relative number size, one more/less than and part–whole relationships. 相似文献
42.
Steven Bourgault Ying Sue Huang 《Journal of Difference Equations and Applications》2013,19(6):739-751
We study real continuous invariants for systems of linear difference equations. We shall prove a conjecture by Ladas about the existence of such invariants. In fact, necessary and sufficient conditions on existence of such invariants will be established. The invariants will be constructed when they exist. 相似文献
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Abstract Introduction to Graphical Modelling by David Edwards, New York: Springer-Verlag, 1995, 274 pp. Reviewed by Garry Robins Introduction to Graphical Modelling by David Edwards, New York: Springer-Verlag, 1995, 274 pp. Reviewed by Garry Robins Graphical Models by Steffen L. Lauritzen, Oxford, U.K.: Clarendon Press, 1996, 298 pp. Reviewed by Garry Robins 相似文献
47.
Angelo Kirchon Jialuo Li Fangqing Xia Gregory S. Day Benjamin Becker Wenmiao Chen Hung‐Jue Sue Yu Fang Hong‐Cai Zhou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12555-12560
Modulation and templating are two synthetic techniques that have garnered significant attention over the last several years for the preparation of hierarchically porous metal–organic frameworks (HP‐MOFs). In this study, by using fatty acids with different lengths and concentrations as dual‐functional modulators/templates, we were able to obtain HP‐MOFs with tunable mesopores that exhibit different pore diameters and locations. We found that the length and concentration of the fatty acids can determine if micelle formation occurs, which in turn dictates the porosity of the resulting HP‐MOFs. The HP‐MOFs with different mesopores differed in their performance in gas uptake and dye adsorption, and the structure–performance relationships were ascribed to the pore diameters and locations. This approach could provide a potentially universal method to efficiently introduce hierarchal mesopores into existing microporous MOF adsorbents with tunable properties. 相似文献
49.
The copper sulfide mineral flotation collector, N‐n‐butyl‐N′‐ethoxycarbonyl‐thiourea (H2bectu), and the 1:1 hexameric copper(I) thioureate complex, [Cu(Hbectu)]6, have been characterized by single crystal X‐ray diffraction. H2bectu crystallizes in the triclinic space group with a = 5.2754(4), b = 9.0042(7), c = 12.6030(9) Å, α = 80.528(6), β = 90.173(6), γ = 76.472(7)°. An intramolecular N‐H···O hydrogen bond between the thioamide proton and carbonyl oxygen forms a planar six‐membered ring in the central core of the molecule with C=O, C=S and C‐N bond lengths in accord with those reported for other N‐alkyl/aryl‐N′‐acyl‐thiourea compounds. [Cu(Hbectu)]6 crystallizes in the monoclinic space group C2/c with a = 23.269(5), b = 13.243(4), c = 23.037(7) Å, β = 91.81(2)° as discrete hexameric clusters disposed about a crystallographic centre of symmetry with a Cu6S6 core consisting of two Cu3S3 chair‐shaped rings linked by coordination of the deprotonated amide nitrogen atom to a copper atom in the adjacent ring. The six ligands assemble as a paddlewheel structure with the ethoxy and n‐butyl substituents packing in an alternating head to tail arrangement. Temperature dependent solution 1H NMR spectroscopic studies show that the hexameric structure of the complex is maintained in solution. 相似文献
50.
Ding S Dudley E Song Q Plummer S Tang J Newton RP Brenton AG 《Rapid communications in mass spectrometry : RCM》2008,22(6):766-772
Terpene lactones are a family of compounds with unique chemical structures, first recognised in an extract of Ginkgo biloba. The discovery of terpene lactone derivatives has recently been reported in more and more plant extracts and even food products. In this study, mass spectrometric characteristics of the standard terpene lactones in Ginkgo biloba were comprehensively studied using both an ion trap and a quadrupole time-of-flight (QTOF) mass spectrometer. The mass spectral fragmentation data from both techniques was compared to obtain the mass spectrometric fragmentation pathways of the terpene lactones with high confidence. The data obtained will facilitate the analysis and identification of terpene lactones in future plant research via the fragmentation knowledge reported here. 相似文献