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611.
Noboru Hamada 《Graphs and Combinatorics》1989,5(1):137-147
Recently, Hamada [5] characterized all {v
2 + 2v
1,v
1 + 2v
0;t,q}-min · hypers for any integert 2 and any prime powerq 3 wherev
l
= (q
l – 1)/(q – 1) for any integerl 0. The purpose of this paper is to characterize all {v
+ 1 + 2v
,v
+ 2v
– 1;t,q}-min · hypers for any integerst, and any prime powerq such thatt 3, 2 t – 1 andq 5 and to characterize all (n, k, d; q)-codes meeting the Griesmer bound (1.1) for the casek 3, d = q
k-1 – (2q
-1 +q
) andq 5 using the results in Hamada [3, 4, 5]. 相似文献
612.
We examined the enantiomer separation with micelles and a micelle-like polymer made with trimethylammonium-terminated surfactants all of whose hydrocarbon chains contain hydrogen bonding valinediamide moieties in electrokinetic chromatography (EKC). The surfactants used were 3-(N-dodecanoyl-L-valylamino)-propyltrimethylammonium bromide (surfactant 1) and 6-(N-nonanoyl-L-valylamino)hexyl-trimethylammonium bromide (surfactant 2); the micelle-like polymer was derived from 3-(N-10-undecenoyl-L-valyl)aminopropyltrimethylammonium bromide (surfactant 3). N-Acylamino acids and their isopropyl esters were separated with enantiomers with the same configuration as the chiral surfactant and which were retained to a greater extent than the counterparts in micelles. The micellar hydrophobic environment, in which amides function as hydrogen bonding sites with solutes, and ceased micellar kinetic association-dissociation with polymerization are discussed. 相似文献
613.
The Raman spectra and polarization parameters of the liquid dimethyl chalcogenides, CH3-X-CH3 (X = 0, S, Se, Te) and the infrared spectra of the gaseous compounds1 have been measured; analysis of these data allow us to deduce much information about the molecular structure. The observed band contours, band types, simplicity of the spectra and the mutual exclusions in the Raman and infrared, are in excellent agreement with the theoretical expectations for a model of D3d symmetry, with a linear C-X-C skeleton.The proton NMR spectra of the molecules CH3-X-CH3 show only one signal. 相似文献
614.
Summary The thermodynamic interaction parameters for linear polyethylene-n-alkanes were investigated with n-C6H14, n-C7H16, n-C8H18, n-C18H38, and n-C32H66 as diluents, by determining the melting temperatures of polyethylene in its mixtures with n-alkanes. It follows that, with increasing the number of carbon atom in n-alkanes, the entropy parameter
1 increases, the enthalpy parameter
1 remains approximately equal to zero, and the free energy parameter
1 decreases and approaches to zero. The change of the interaction parameters with the number of carbon atom in n-alkanes were discussed byPrigogine's theory.
Zusammenfassung Die thermodynamischen Wechselwirkungsparameter für das System lineares PolyÄthylen/n-Alkane wurden durch die Schmelzpunktsmessungen von PolyÄthylen in den Mischungen mit n-Alkanen bestimmt. Die als Verdünnungsmittel verwandten n-Alkane waren n-C6H14, n-C7H16, n-C8H18, n-C18H38 und n-C32H66. Es wurde gefunden, da\ mit steigender Zahl der Kohlenstoffatome in den n-Alkanen der Entropieparameter 1 zunimmt, wÄhrend der Enthalpieparameter 1 annÄhernd Null bleibt. Der Parameter der freien Energie 1 nimmt ab und nÄhert sich Null. Die VerÄnderung der Wechselwirkungsparameter von der Zahl des Kohlenstoffatome in den n-Alkanen wurden nach der Prigogineschen Theorie diskutiert.相似文献
615.
[reaction: see text] New phosphine ligands possessing both axial chirality and a chirogenic phosphorus center were prepared from (R)-2-bromo-2'-N,N-(dimethylamino)-1,1'-binaphthyl (1) via a simple Li-halogen exchange protocol. The asymmetric vinylation of a ketone enolate with (R,R(P))-2-(tert-butylphenylphosphino)-2'-N,N-(dimethylamino)-1,1'-binaphthyl (2a) afforded the coupling product with good enantiomeric excess. 相似文献
616.
[reaction: see text] We have recently developed a new class of chiral phosphorus ligands: P-chirogenic diaminophosphine oxides. These pentavalent phosphorus compounds have been successfully applied to Pd-catalyzed asymmetric construction of tertiary and quaternary carbons. The actual ligand structure was the trivalent phosphorus species 17, which was generated in situ by BSA-induced P(V) to P(III) transformation of 6, the preligand. Detailed mechanistic studies, including asymmetric amplification and initial rate kinetics, revealed that complex 18 [Pd-17 (1:2) complex] was the active catalyst. The important function of the nitrogen atom on the sidearm in the ligands was also clarified. The source of enantioselection in the construction of asymmetric quaternary carbons was the secondary ligand substrate interaction mediated by N-Zn coordination. 相似文献
617.
Tatsuo Hamada 《Tetrahedron letters》2003,44(23):4343-4346
To design easily cyclizable seco-acid derivatives of lankanolide, the conformation of several model seco-acids was calculated and the lactonization experiments of the seco-acids were carried out to elucidate the efficiency of the cyclization of the model seco-acid. 相似文献
618.
Toshiyuki Hamada Hiroshi Hirota Shigeyuki Yokoyama Masanori YamaguchiNobumasa Otsubo Hideharu IshidaMakoto Kiso Akiko KanamoriReiji Kannagi 《Tetrahedron letters》2003,44(6):1167-1170
The structure of cyclic sialyl 6-sulfo Lewis x, a new biologically dormant form of L-selectin ligand, was determined unambiguously by the accurate NMR analysis to have the lactamized
[5.], (a), (b),
[2.], (a) and (b)B conformation of its sialic acid. For the NMR structure elucidation were used various informations, such as chemical shifts values, appearance of amide proton, and NOE. 相似文献
619.
Study on the constituents of Desmodium styracifolium 总被引:2,自引:0,他引:2
T Kubo S Hamada T Nohara Z R Wang H Hirayama K Ikegami K Yasukawa M Takido 《Chemical & pharmaceutical bulletin》1989,37(8):2229-2231
Two triterpenoid saponins (1 and 2) were isolated from Desmodii Herba [the dried whole plants of Desmodium styracifolium (Osbeck) Merr. (Leguminosae)] and their chemical structures were characterized as soyasaponin I and a new saponin, 3-O-[alpha-L-rhamnopyranosyl-(1----2)-beta-D-galactopyranosyl- (1----2)-beta-D-glucuronopyranosyl]soyasapogenol E, respectively, by chemical and spectroscopic means. 相似文献
620.
Yoko Sugawara Yoshiaki Hamada Akiko Y. Hirakawa Masamichi Tsuboi 《Chemical physics letters》1979,67(1):186-188
In the 0.12 cm?1 resolution infrared absorption spectrum of gaseous N-methylformamide, a progression of peaks with a spacing of about 2.6 cm?1 has been found in the 610-540 cm?1 region. This is assignable to a conformer with the CO and NH bonds cis to each other. 相似文献