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601.
We propose algorithms to perform two new operations on an arrangement of line segments in the plane, represented by a trapezoidal map: the split of the map along a given vertical line D, and the union of two trapezoidal maps computed in two vertical slabs of the plane that are adjacent through a vertical line D. The data structure we use is a modified Influence Graph, still allowing dynamic insertions and deletions of line segments in the map. The algorithms for both operations run in O(sD logn+log2n) time, where n is the number of line segments in the map, and sD is the number of line segments intersected by D. 相似文献
602.
603.
Laurent Spina Monique Tillard Claude Belin 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):i9-i10
The title compound, lithium aluminium silicide (15/3/6), crystallizes in the hexagonal centrosymmetric space group P63/m. The three‐dimensional structure of this ternary compound may be depicted as two interpenetrating lattices, namely a graphite‐like Li3Al3Si6 layer and a distorted diamond‐like lithium lattice. As is commonly found for LiAl alloys, the Li and Al atoms are found to share some crystallographic sites. The diamond‐like lattice is built up of Li cations, and the graphite‐like anionic layer is composed of Si, Al and Li atoms in which Si and Al are covalently bonded [Si—Al = 2.4672 (4) Å]. 相似文献
604.
Marianne Vialemaringe Marie‐Josphe Bourgeois Monique Campagnole Evelyne Montaudon 《Helvetica chimica acta》2000,83(3):616-629
Isomerization of Functionalized 2,3‐Epoxypinanes in the Presence of Lewis Acids The functionalized 2,3‐epoxypinanes 1b – i were submitted to isomerization in the presence of ZnBr2 at 110° (Table 1) or of BF3⋅Et2O at different temperatures (Table 2), and their behavior was compared with that of the non‐functionalized parent 1a and with similar known transpositions. The produced campholenals 2 , pinocamphones 3 , and in some cases, fencholenals 4 were isolated and characterized. A mechanism involving a concerted oxirane ring opening is proposed (Scheme 4). 相似文献
605.
Bert Vanhaecht Marcel N. Teerenstra Davy R. Suwier Rudolph Willem Monique Biesemans Cor E. Koning 《Journal of polymer science. Part A, Polymer chemistry》2001,39(6):833-840
A series of copolyamides 12.y was synthesized either with y = 6, or 1,4‐cyclohexanedicarboxylic acid (1,4‐CHDA) residue, or a mixture of both. The influence of the synthetic route of 1,4‐CHDA containing polyamides on the obtained cis–trans ratio of the incorporated 1,4‐CHDA was investigated. The use of acid chlorides provided a synthetic route with full control of the cis–trans ratio of the 1,4‐CHDA residue during synthesis, whereas synthesis at elevated pressure and temperature caused isomerization. The content and cis–trans ratio of 1,4‐CHDA in the copolyamides were determined by solution 13C NMR spectroscopy. Increasing the degree of partial substitution of the adipic acid by 1,4‐CHDA resulted in an increase in Tm, even for low molar precentages of 1,4‐CHDA. This phenomenon points to isomorphous crystallization of both the 12.6 and 12.CHDA repeating units. The mps of the synthesized polyamides were independent of the initial cis–trans ratio of 1,4‐CHDA, provided that the samples were annealed at 300 °C before DSC analysis. The polyamides exhibited a different melting pattern depending on the 1,4‐CHDA content. At a low a 1,4‐CHDA content a net exothermic recrystallization occurred during melting, whereas at higher contents of 1,4‐CHDA this recrystallization occurs to a lesser extent, and two separate melting areas are observed. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 833–840, 2001 相似文献
606.
Rudolph Willem Hassan Dalil Monique Biesemans Jos C. Martins Marcel Gielen 《应用有机金属化学》1999,13(8):605-608
The reaction of hexafluoro‐2,2‐bis(4‐carboxyphenyl)propane with tetrabutyldipropoxydistannoxane, formed in situ from dibutyltin oxide and n‐propanol in benzene, yields a compound the structure of which is a strained macrocycle with a single dicarboxylate moiety. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
607.
608.
609.
Flavone C-glycosides from Viola yedoensis MAKINO 总被引:4,自引:0,他引:4
A new flavone C-glycoside, apigenin 6-C-alpha-L-arabinopyranosyl-8-C-beta-L-arabinopyranoside, has been isolated from Viola yedoensis together with the known compounds, apigenin 6,8-di-C-alpha-L-arabinopyranoside, apigenin 6-C-alpha-L-arabinopyranosyl-8-C-beta-D-glucopyranoside (isoschaftoside), apigenin 6-C-beta-D-glucopyranosyl-8-C-alpha-L-arabinopyranoside (schaftoside), apigenin 6-C-beta-D-glucopyranosyl-8-C-beta-L-arabinopyranoside (neoschaftoside), apigenin 6,8-di-C-beta-D-glucopyranoside (vicenin-2), apigenin 6-C-alpha-L-arabinopyranosyl-8-C-beta-D-xylopyranoside, apigenin 6-C-beta-D-xylopyranosyl-8-C-alpha-L-arabinopyranoside, luteolin 6-C-beta-D-glucopyranoside (isoorientin) and luteolin 6-C-alpha-L-arabinopyranosyl-8-C-beta-D-glucopyranoside (isocarlinoside). The structures were determined by spectroscopic methods and new or revised (1)H- and (13)C-NMR spectral assignments are proposed for some compounds. 相似文献
610.
David A. Pérez Berrocal Dr. Thimmalapura M. Vishwanatha Dr. Daniel Horn-Ghetko J. Josephine Botsch Laura A. Hehl Dr. Sebastian Kostrhon Dr. Mohit Misra Prof. Dr. Ivan Ðikić Dr. Paul P. Geurink Dr. Hans van Dam Prof. Dr. Brenda A. Schulman Dr. Monique P. C. Mulder 《Angewandte Chemie (International ed. in English)》2023,62(32):e202303319
Protein post-translational modification with ubiquitin (Ub) is a versatile signal regulating almost all aspects of cell biology, and an increasing range of diseases is associated with impaired Ub modification. In this light, the Ub system offers an attractive, yet underexplored route to the development of novel targeted treatments. A promising strategy for small molecule intervention is posed by the final components of the enzymatic ubiquitination cascade, E3 ligases, as they determine the specificity of the protein ubiquitination pathway. Here, we present UbSRhodol, an autoimmolative Ub-based probe, which upon E3 processing liberates the pro-fluorescent dye, amenable to profile the E3 transthiolation activity for recombinant and in cell-extract E3 ligases. UbSRhodol enabled detection of changes in transthiolation efficacy evoked by enzyme key point mutations or conformational changes, and offers an excellent assay reagent amenable to a high-throughput screening setup allowing the identification of small molecules modulating E3 activity. 相似文献