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51.
A computational study is made of the effect of basis set upon the energy, properties and inversion barrier of the phosphine molecule. The calculations are performed at both the SCF and CI level. The flexibility of the double zeta basis is discussed in the light of the results. 相似文献
52.
The structure and the relative stability of isomers of molecules X2H2F2 (X=Si, Ge, Sn) have been studied using the density functional theory (DFT). We have determined the optimised structures of the substituted isomers. The XX bond have been studied and compared to that of the parent molecules: X2H4. It appears that, for the planar and trans ethylenic systems, the double bond character of the XX decreases when the hydrogen atoms are substituted by fluorine atoms. The most stable structure is shown to be the one where the two fluorine atoms are fixed on the same atom. The bridged structures are also studied. 相似文献
53.
The reaction of imidazole with benzoyl chloride in pyridine affordedcis-1,2-bis(benzoyl-amino)ethylene (1) rather than 2-benzoylimidazole, as has been suggested previously. The structure of1 was confirmed by1H NMR spectroscopy and X-ray diffraction study.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1593–1595, August, 1998. 相似文献
54.
In a comparative study the in vitro corrosion behavior of a selection of nickel- and cobalt-based alloys for application in
dentistry containing no noble metals was studied with slow scan cyclic voltammetry. The obtained breakthrough potentials,
the repassivation behavior and further typical features of the cyclic voltamograms are correlated with the chemical composition
as measured with electron beam microanalysis. Surface inhomogenities detected with the latter method are discussed with respect
to the electrochemical behavior. For all alloys stabilities in terms of breakthrough potential superior to previously reported
data for nickel-base alloys are found. 相似文献
55.
Pyrolysis study of fluorinated sol-gel silica 总被引:1,自引:0,他引:1
Fluorinated silica gels at various fluorine content were prepared via sol-gel by hydrolysis of 3,3,3-trifluoropropyltrimethoxysilane
and tetraethoxysilane mixtures. The gels, of nominal stoichiometry Si(CH2CH2CF3)XO(2-X/2)(X=0.1-1), were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS) and N2 adsorption analysis. The thermal stability of the fluorinated samples was investigated by coupling thermogravimetric measurements
with mass spectrometric and gas chromatographic analyses of the evolved gaseous species. The chemical reactions occurring
in the gel matrices during heating were siloxane chain rearrangements involving condensation between residual hydroxyl and
ethoxyl groups in the 100-350°C temperature range, whereas the thermal decomposition of the fluoroalkyl groups were observed
at higher temperatures (450-600°C). The release of the fluoroalkyl moieties also involved C-F/Si-O bond exchanges inside the
siloxane chains, with gas-phase evolution of different fluorinated silicon units.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
56.
A. N. Bilyachenko A. A. Korlyukov M. M. Levitskii M. Yu. Antipin B. G. Zavin 《Russian Chemical Bulletin》2007,56(3):543-545
The first cage-like ferrophenyl siloxane containing FeIII ions in different coordination spheres (four iron ions have a trigonal-bipyramidal coordination and two iron ions have a
distorted octahedral coordination) was synthesized by the exchange reaction of sodium phenylsilanolate with FeIII chloride. An exotic lantern-like structure is formed with the involvement of two metal oxide fragments Fe—O—Fe. The structure
of this compound was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 522–524, March, 2007. 相似文献
57.
Single nucleotide polymorphisms (SNPs) are currently being mapped and databased at a remarkable pace, providing a viable means for understanding disease susceptibility, differential drug response and human evolution. Consequently, there is an increasing demand for SNP genotyping technologies that are simple, rapid, cost effective and readily amenable to automation for high-throughput analyses. In this study, we improved the Survivor Assay, a SNP detection method based on electrospray ionization mass spectrometry (ESI-MS), with several developments. One improvement is the development of a one-well assay, requiring no off-line purification of the polymerase chain reaction product, achieved by simple addition of reagent solution into a single well. Another is the on-line separation of magnesium and dideoxynucleotides using an in-house made monolithic metal chelating column, eliminating any off-line sample preparation prior to mass spectrometric analysis. Here the Survivor Assay is extended from a proof-of-principle concept to a validated method by genotyping six SNPs from five different regions of human genomic DNA in 55 individual samples with 100% accuracy. This improved Survivor Assay eliminates the tedious and time-consuming steps of sample preparation, minimizes sample handing and offers a high-throughput analysis of SNPs by ESI-MS. The current combined preparation and analysis time is 2 min per sample. The simplicity of this method has potential for full automation and parallel chromatography and, thus, reduced analysis time. In addition, we have adapted the Survivor Assay for quantitative SNP analysis in pooled DNA samples. The capabilities and sensitivity of this approach were evaluated. We demonstrate that an allele occurring at a frequency of 2% can consistently be quantitated. 相似文献
58.
V. F. Mironov A. V. Bogdanov A. V. Nemtarev A. A. Shtyrlina E. N. Varaksina V. K. Cherkasov A. B. Dobrynin D. B. Krivolapov R. Z. Musin I. A. Litvinov A. I. Konovalov 《Russian Chemical Bulletin》2007,56(9):1900-1910
The reactions of 3,5-di(tert-butyl)-1,2-benzoquinone with aryl-and alkylacetylenes in the presence of phosphorus trichloride afford 4-aryl(alkyl)-8-tert-butyl-2,6-dichloro-2-oxo-2H-benzo[e][1,2]oxaphosphinines as the major ipso-substitution products of the tert-butyl group by the chlorine atom. 4-Aryl(alkyl)-6,8-di(tert-butyl)-2,5-dichloro-2-oxo-and 4-aryl(alkyl)-6-tert-butyl-2,8-dichloro-2-oxo-2H-benzo[e][1,2]oxaphosphinines were obtained as the minor products. The structures of the stable representatives of this series were
confirmed by X-ray diffraction.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1836–1845, September, 2007. 相似文献
59.
A mixed ligand 12 complex of copper(II) azide with 3,5-lutidine, namely di-(1,1)-azido-di(0,0)-nitrato)tetrakis(3,5-lutidine)dicopper(II) has been prepared and characterized by X-ray crystallographic and spectroscopic methods. The dimeric molecule, which possesses a crystallographic inversion center, contains two(1,1) bridging azido ligands. Each copper(II) atom in the cyclic Cu2N2 unit is further coordinated by two oxygen atoms from two(0,0-nitrato) bridges at Cu-O distances of 2.465(3) and 2.568(3) Å and two nitrogen atoms from the lutidine molecules [Cu-N=2.003(3) and 2.012(3) Å] to give a distorted tetragonal bipyramid. Both azido ligands are linear [N-N-N angle=179.0(4) and asymmetric N-N=1.207(4) and N-N=1.135(5) Å]. The azido bridges produce a rather short Cu Cu distance of 3.013(2) Å. Infrared and electronic data are presented and discussed. 相似文献
60.
Takeharu Haino 《Tetrahedron letters》2005,46(9):1411-1414
C60-linked calix[5]arenes were synthesized and their intramolecular binding properties were investigated. The self-inclusion ratio of the C60 moiety was determined by using UV-vis spectroscopy, and the ratio depends on chain length, temperature, and solvent. Influence of temperature and solvent was explained by the thermodynamic data of the intramolecular complex formation process. 相似文献