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41.
The asymmetric synthesis of trans-substituted cyclopropanecarboxylic acid derivatives is achieved via stereoselective nucleophilic methylene transfer to E-,β-unsaturated acyl ligands bound to the iron chiral auxiliary [(η5-C5H5)Fe(CO)(PPh3)]. 相似文献
42.
Sevim Akyüz Tanil Akyüz J. Eric D. Davies 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(2):105-119
The adsorption of 4,4-bipyridyl by natural sepiolite and smectite group clay minerals (bentonite, hectorite and saponite) from Anatolia (Turkey) has been studied using vibrational spectroscopy. Investigation of Fourier-transform infrared and Fourier-transform Raman spectra of adsorbed 4,4-bipyridyl indicate the presence of chemisorbed species. However, any evidence for the generation of anionic species on the surface of the phyllosilicates has not been detected. It is proposed that the adsorbed bipyridyl molecules on sepiolite are centrosymmetric and H-bonded to the surface hydroxyls through both the nitrogen lone pairs as bidentate ligands. The adsorbed bipyridyl molecules on the smectite group clays are coordinated to exchangeable cations both directly and also indirectly through water as monodentate ligands. XRD patterns of the clays studied are also recorded. 相似文献
43.
D. H. Davies D. C. Phillips J. D. B. Smith 《Journal of polymer science. Part A, Polymer chemistry》1979,17(4):1153-1161
To elucidate mechanisms in electroinitiated polymerization reactions a comparison was conducted between ultraviolet (UV) photoinitiation and electroinitiation of N-vinyl phthalimide with zinc chloride as a catalyst. Both methods give low yields of a complex polymer product. A detailed analysis, infrared (IR), gel permeation chromatography (GPC), elemental, and molecular weight, conducted on the polymeric products, indicated that phthalimide ring opening was occurring and that complex mixtures of poly(N-vinyl phthalimide) derivatives were formed. Both initiation methods gave comparable results, which further indicated mechanistic similarity between photo-and electroinitiation in these donor–acceptor charge transfer polymerizations. 相似文献
44.
Non-linear dielectric spectroscopy: antifouling and stabilisation of electrodes by a polymer coating
Woodward AM Davies EA Denyer S Olliff C Kell DB 《Bioelectrochemistry (Amsterdam, Netherlands)》2000,51(1):13-20
Non-linear dielectric spectroscopy (NLDS) has previously been shown to produce quantitative information that is indicative of the metabolic state of various organisms, by modeling the non-linear effects of their membranous enzymes on an applied oscillating electromagnetic field using supervised multivariate analysis methods. However, the instability of the characteristics of the measuring apparatus rendered the process temperamental at best in the laboratory and impractical for field use. The main practical problem, of the non-stationarity of the electrode-solution interface and the ease with which the electrode surfaces are subject to protein fouling. It is addressed by applying a thin, electrically transparent antifouling coat to the electrodes. This reduces the interminable cleaning procedures previously required to prepare the electrodes for use, increases their usable lifetime before recleaning, and also improves the precision and linearity of multivariate models on NLDS data. 相似文献
45.
A. N. Veselkov L. N. Dymant P. A. Bolotin S. F. Baranovskii D. Shipp D. Davies 《Journal of Structural Chemistry》1996,37(1):65-75
Complexation of the ethidium bromide (3,8-diamino-6-phenyl-5-ethylphenanthridine) dye with self-complementary deoxytetraribonucleoside
triphosphate 5′-d(CpGpCpG) in a water-salt solution is studied by one- and two-dimensional1H NMR spectroscopy (500 MHz). Two-dimensional PMR spectroscopy (2D-COSY and 2D-NOESY) is used for the full assignment of proton
signals of the molecules in the solution and for the qualitative analysis of the interaction between ethidium bromide and
the tetranucleotide. The concentration dependences of the proton chemical shifts of the molecules at a fixed temperature (T=308
K) are measured. Different schemes of the formation of the dye complexes with the tetranucleotide, taking into account various
molecular associations in the solution are considered. The equilibrium constants of the reactions and the limiting chemical
shifts of ethidium bromide protons in the complexes are determined. The relative contents of different complexes in the solution
are analyzed, and the dynamic equilibrium is studied as a function of the dye-tetranucleotide ratio in the solution. The data
obtained suggest that ethidium bromide (like the acridine dye proflavine) is intercalated predominantly into the pyrimidine-purine
sections (CG sites) of the tetranucleotide duplex. However, ethidium bromide is intercalated on the side of the narrow slot
of the duplex, while proflavine intercalation occurs through the broad slot of the double helix. The most likely structures
of the 1∶2 and 2∶2 dye-tetranucleotide complexes in the solution are constructed using the calculated values of the induced
chemical shifts of ethidium bromide protons and 2D NOESY spectroscopy data.
Sevastopol State Technical University. Berkbeck College, London University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 1, pp. 75–87, January–February, 1996.
Translated by I. Izvekova 相似文献
46.
Jasminka Mizdrak Peter G. Hains Danuta Kalinowski Michael J. Davies Joanne F. Jamie 《Tetrahedron》2007,63(23):4990-4999
4-(2-Aminophenyl)-4-oxobutanoic acid, 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid and glutathionyl-kynurenine have been identified as novel metabolites in normal and cataractous human lenses following total synthesis and comparison with authentic human lens samples. Their structures are consistent with those derived from the major human lens UV filters kynurenine and 3-hydroxykynurenine, and it is proposed that these compounds also play a role as UV filters. These metabolites were isolated in pmol/mg levels (dry mass) in lenses. 4-(2-Amino-3-hydroxyphenyl)-4-oxobutanoic acid and glutathionyl-kynurenine were found to be unstable at physiological pH. Other potential metabolites, glutathionyl-3-hydroxykynurenine, kynurenine yellow and 3-hydroxykynurenine yellow, were not detected in either normal or cataractous lenses. 相似文献
47.
Davies RP Linton DJ Schooler P Snaith R Wheatley AE 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(17):3696-3704
The sequential reaction of ZnMe2 with a 2-pyridylamine (HN(2-C5H4N)R, R = Ph: 1; 3,5-Xy (=3,5-xylyl): 2; 2,6-Xy: 3; Bz (=benzyl): 4; Me: 5), tBuLi and thereafter with oxygen affords various lithium zincate species, the solid-state structures of which reveal a diversity of oxo-capture modes. Amine 1 reacts to give both dimeric THF [Li(Me)OZn[N(2-C5H4N)Ph]2] (6), wherein oxygen has inserted into the Zn-C bond of a [MeZn[N(2-C5H4N)-Ph]2] ion, and the trigonal Li2Zn complex, bis(OtBu)-capped (THF x Li)2-[[(mu3-O)tBu]2Zn[N(2-C5H4N)Ph]2] (7). The structural analogue of 6 (8) results from the employment of 2, while the use of more sterically congested 3 yields a pseudo-cubane dimer [(THF x [Li(tBu)OZn(OtBu)Me]]2] (9) notable for the retention of labile Zn-C(Me). Amines 4 and 5 afford the oxo-encapsulation products [mu4-O)Zn4[(2-C5H4N)-NBz]6] (10b), and [tBu(mu3-O)-Li3(mu6-O)Zn3[(2-C5H4N)NMe]6] (11), respectively, with concomitant oxo-insertion into a Li-C interaction resulting in capping of the fac-isomeric (mu6-O)M3M'3 distorted octahedral core of the latter complex by a tert-butoxide group. 相似文献
48.
A method based on dialysis in the presence of histidine, and subsequent copper adsorption and preconcentration using Chelex-100 resin, has been developed for selective extraction of exchangeable copper from blood plasma. The method was verified by comparative analysis using two different instrumental techniques, ICP–MS and AAS. The results obtained were in excellent agreement. Accurate quantification of the exchangeable copper and the firmly bound copper was achieved. The method was further validated by analysis of a lyophilised human serum certified reference material. 相似文献
49.
E. B. Davies 《Communications in Mathematical Physics》1980,71(3):277-288
By carrying out a general analysis of properties of the wave operators for the non-unitary scattering theory which arises in connection with the use of complex optical potentials in nuclear scattering and elsewhere, we clarify some puzzling differences between two recent approaches to this subject. 相似文献
50.
J.C. Hardy G.C. Ball W.G. Davies J.S. Forster H. Schmeing E.T.H. Clifford 《Nuclear Physics A》1981,357(2):356-364
The Q-value for the 129Xe(3He, d)130Cs reaction is measured to be +5 ± 20 keV. By combining this result with the known neutron separation energy of 130Xe, we derive the total decay energy of 130Cs130Xe to beQEC = 2974 ± 20 keV. This value agrees well with two previous positron end-point measurements but disagrees with the corresponding value derived from the 1977 atomic mass evaluation. This has significance in testing the accuracy of the calculated ratio for 130Cs decay. The mass excess of 130Cs is derived to be ?86908 ± 14 keV. An excited state in 130Cs. was also identified at 121 ± 15 keV with J < 3 and positive parity. The Q-value for 136Xe(3He, d)137Cs was measured to be 1918 ± 12 keV. 相似文献