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排序方式: 共有463条查询结果,搜索用时 15 毫秒
1.
Ammar R Ball RC Banerjee S Bhat PC Bosetti P Bromberg C Canough GE Coffin T Dershem TO Dixon RL Fenker HC Ganguli SN Gensch U Girtler P Goshaw AT Grard F Gurtu A Hamilton C Henri VP Hernandez JJ Hrubec J Iori M Jones LW Kuhn D Knauss D Leedom ID Legros P Lemonne J Leutz H Liu X Malhotra PK Marraffino JM Mendez GE Miller R Naumann T Nguyen A Nowak H Pilette P Poirier J Poppleton A Raghavan R Rasner K Reucroft S Robertson WJ Roe BP Roth A Senko M Struczinski W Subramanian A Touboul MC Vonck B 《Physical review letters》1988,61(19):2185-2188
2.
S. Banerjee S. N. Ganguli A. Gurtu R. Raghavan A. Subramanian Y. Goldschmidt-Clermont R. T. Ross S. Squarcia K. Dziunikowska T. Haupt P. Girtler D. Kuhn K. W. J. Barnham J. Wells P. R. S. Wright J. Macnaughton F. Mandl F. Shabaan M. Bardadin-Otwinowska M. Szczekowski 《Zeitschrift fur Physik C Particles and Fields》1986,31(3):401-408
Results on inclusive ? production inK ? p interactions at 110 GeV/c are presented. The production cross section is found to be larger than in πp andpp interactions at similar energies, suggesting OZI allowed \(s\bar s\) fusion to be the dominant mechanism in ? production. Thex distributions of ? and \(\bar K^{*0} \) are found to be similar to each other over the entirex range suggesting an overall strangeness suppression factor of 0.20±0.04 in the sea to be the dominant source of the difference in the cross section for ? and \(\bar K^{*0} \) . There is no evidence of a narrowφπ ? state around 2.1 GeV/c2 as suggested byK + experiments, but there is some excess of events in the region 1.94?1.98 GeV/c2 consistent with theF-meson mass as observed ine + e ? experiments. 相似文献
3.
M.I. Bruce O.M.Abu Salah R.E. Davis N.V. Raghavan 《Journal of organometallic chemistry》1973,64(3):C48-C50
In contrast to a related iron—copper compound, the complex (π-C5H5)Ru(PPh3)2(C2Ph)CuCl is shown to be monomeric, and contains linear dicoordinate copper(I); the reactions of this and similar complexes with metal carbonyls are sources of new mixed-metal clusters, such as (π-C5H5)Fe2 Ru(C2Ph)(CO)6 (PPh3). 相似文献
4.
Raghavan Krishnan S. A. Lang Marshall M. Siegel 《Journal of heterocyclic chemistry》1986,23(6):1801-1804
The synthesis of 3-amino-7-chloro-1-ethyl-6-fluoro-4(1H)quinolinone derivatives is described. These were investigated for their antibacterial activity. 相似文献
5.
Tripathi SK Patel U Roy D Sunoj RB Singh HB Wolmershäuser G Butcher RJ 《The Journal of organic chemistry》2005,70(23):9237-9247
[Structure: see text]. The synthesis and characterization of a series of organochalcogen (Se, Te) compounds derived from benzyl alcohol 13 are described. The synthesis of the key precursor dichalcogenides 15, 22, and 29 was achieved by the ortho-lithiation route. Selenide 18 was obtained by the reaction of the dilithiated derivative 14 with Se(dtc)2. Oxidation of 15 and 22 with H2O2 afforded the corresponding cyclic ester derivatives 17 and 24, respectively. Oxidation of selenide 18 with H2O2 affords the spirocyclic compound 19. The presence of intramolecular interactions in dichalcogenides 15 and 22 has been proven by single-crystal X-ray studies. The cyclic compounds 17 and 19 have also been characterized by single-crystal X-ray studies. GP(X)-like antioxidant activity of selenium compounds has been evaluated by the coupled bioassay method. Density functional theory calculations at the mPW1PW91 level on ditelluride 22 have identified a fairly strong nonbonding interaction between the hydroxy oxygen and tellurium atom. The second-order perturbation energy obtained through NBO analysis conveys the involvement of n(O) --> sigma(Te-Te) orbital overlap in nonbonding interaction. Post wave function analysis with the Atoms in Molecules (AIM) method identified distinct bond critical point in 15 and 22 and also indicated that the nonbonding interaction is predominantly covalent. Comparison between diselenide 15 and ditelluride 22 using the extent of orbital interaction as well as the value of electron density at the bond critical points unequivocally established that a ditelluride could be a better acceptor in nonbonding interaction, when the hydroxy group acts as the donor. 相似文献
6.
Patra S Sarkar B Ghumaan S Patil MP Mobin SM Sunoj RB Kaim W Lahiri GK 《Dalton transactions (Cambridge, England : 2003)》2005,(7):1188-1194
The isomeric title complexes were obtained in almost equimolar ratio from the reaction of Ru(trpy)Cl3 and L. Crystal structure analyses of the perchlorate hemihydrates, electrochemical and spectroscopic (NMR, UV/VIS, EPR) studies, supported by DFT calculations, reveal distinct differences between the isomeric redox series [1]n+(tetrazine-Nt trans to Cl) and [2]n+(pyrazolyl-Np trans to Cl; n= 0, 1, 2). The latter system with the pi acceptors trpy and tetrazine in the equatorial plane and the pyrazolyl and chloride donors in the axial positions exhibits facilitated oxidation, lower energy MLCT transitions, more balanced chelate coordination, and a higher g anisotropy in the oxidised (RuIII) state. According to partially resolved EPR spectra of one-electron reduced neutral compounds and they have the unpaired electron predominantly in the tetrazine ring of L. 相似文献
7.
Pyrolysis-gas chromatography was applied to the characterization of ground beef and soy protein isolate and its mixtures at the 50, 30 and 10% levels. A cryogenic trap pyrolysis mode was employed and the volatile pyrolysates were analysed by a high-resolution capillary gas chromatograph. Two phenolic derivatives, o-methoxy- and dimethoxyphenol, as well as 2,3-dithiabutane are uniquely observed at a large concentration in the soy pyrolysate. Quantification of these characteristic compounds allow the estimation of the level of soy inclusion in the mixture. This approach effectively denotes soy addition up to the 10% level in comminuted beef. 相似文献
8.
Bhaskar M Gnanamani A Ganeshjeevan RJ Chandrasekar R Sadulla S Radhakrishnan G 《Journal of chromatography. A》2003,1018(1):117-123
Extracellular fluid protein (ECFP) of Streptomyces species SS07 has been used to reduce water soluble azo dyes and the carcinogenic amines released have been compared with that from chemical reduction. The effect of temperature, pH and contact time on the recovery of amines using ECFP was studied. The ECFP releases carcinogenic amines at a pH of 9.2 and a temperature of 37 degrees C for a contact period of 24 h. The reduction products were analyzed with HPLC and their structures confirmed by LC-MS and GC-MS. It was observed that both the ECFP and chemical reduction methods released similar type of amine products. In the case of dye samples, compared to chemical reduction, 5-20% increase in the release of carcinogenic amines by ECFP was observed. The percentage of amine products released by chemical reduction was higher for leather garment samples compared to ECFP treatment. 相似文献
9.
N-Heterocyclic carbenes (NHCs) belong to the popular family of organocatalysts used in a wide range of reactions, including that for the synthesis of complex natural products and biologically active compounds. In their organocatalytic manifestation, NHCs are known to impart umpolung reactivity to aldehydes and ketones, which are then exploited in the generation of homoenolate, acyl anion, and enolate equivalents suitable for a plethora of reactions such as annulation, benzoin, Stetter, Claisen rearrangement, cycloaddition, and C–C and C–H bond functionalization reactions and so on. A common thread that runs through these NHC catalyzed reactions is the proposed involvement of an enaminol, also known as the Breslow intermediate, formed by the nucleophilic addition of an NHC to a carbonyl group of a suitable electrophile. In the emerging years of NHC catalysis, enaminol remained elusive and was largely considered a putative intermediate owing to the difficulties encountered in its isolation and characterization. However, in the last decade, synergistic efforts utilizing an array of computational and experimental techniques have helped in gaining important insights into the formation and characterization of Breslow intermediates. Computational studies have suggested that a direct 1,2-proton transfer within the initial zwitterionic intermediate, generated by the action of an NHC on the carbonyl carbon, is energetically prohibitive and hence the participation of other species capable of promoting an assisted proton transfer is more likely. The proton transfer assisted by additives (such as acids, bases, other species, or even a solvent) was found to ease the kinetics of formation of Breslow intermediates. These important details on the formation, in situ detection, isolation, and characterization of the Breslow intermediate are scattered over a series of reports spanning well over a decade, and we intend to consolidate them in this review and provide a critical assessment of these developments. Given the central role of the Breslow intermediate in organocatalytic reactions, this treatise is expected to serve as a valuable source of knowledge on the same.Molecular insights on the formation, detection, and even isolation of the Breslow intermediate, which is the most important species in N-heterocyclic carbene (NHC) catalysis, as obtained from experimental and computational studies, are presented. 相似文献
10.
Biju Mathew B. Narayana B. Muralidhara Rao C. H. Raghavan Nambiar B. Ramachandra 《Mikrochimica acta》1996,122(3-4):295-299
A simple and accurate complexometric method is proposed for the determination of Tl(III) using semicarbazide hydrochloride as a releasing agent. In the presence of diverse metal ions, thallium is complexed first with a known excess of EDTA, and the surplus EDTA is then titrated with standard zinc sulfate at pH 5.0–6.0 (hexamine) using xylenol orange indicator. An excess of 5% aqueous neutral solution of semicarbazide hydrochloride is then added and the released EDTA is titrated against standard zinc sulfate solution. The method works well in the range 2–50 mg of Tl(III) with relative errors < 0.5%, standard deviations 0.05mg and coefficient of variation 0.4%. The method is applied for the determination of thallium content in complexes and alloy compositions 相似文献