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101.
The mass spectrometric investigation of specifically deuterium and 13C labelled 2-trimethylsilyl-l-phenoxyethanes proves that the dissociative ionization of β-silyl-substituted ethane derivatives (loss of PhO?; p-CH3C6H4O?; and C4H?9 from PhOCH2CH2SiMe3, p-MeC6H4OCH2CH2SiMe3 and CH3CH2CH(CH3)CH2-CH2SiMe3, respectively) yields the non-classical bridge ethylene trimethylsilanium ion and not the open-chain isomer. Other stable C5H13Si+? ions, characterised by collisional activation mass spectrometry, are the dimethyl n-propyl silicenium ion and the l-trimethylsilyl ethyl cation, both generated from the molecular ions of CH3CH2CH2Si(Cl)Me2 and CH3CH(Cl)SiMe3 via unimolecular loss of Cl?. 相似文献
102.
103.
Matthias Bauer Christoph Gastl Christoph Köppl Guido Kickelbick Helmut Bertagnolli 《Monatshefte für Chemie / Chemical Monthly》2006,137(5):567-581
Summary. The molecular structure of the transition metal alkoxide Zr(OnBu)4 in toluene and its modification by addition of i-propanol, tetrahydrofurane, and the coordinating ligand pentane-1,3-dione (Hacac) were investigated by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy.
Zr(OnBu)4 dissolved in toluene forms dimers. It was proved that cluster size is a function of the number of added equivalents ligand.
In contrast, the addition of i-propanol or tetrahydrofurane caused no structural changes observable by EXAFS spectroscopy. A detailed discussion of the
structural models is given in terms of possible alternatives and errors within the EXAFS analysis. 相似文献
104.
Helmut Bode und Karl Wulff 《Fresenius' Journal of Analytical Chemistry》1966,219(1):32-48
Zusammenfassung Es wird ein Verfahren zur Bestimmung kleiner Cd-Mengen neben der 104-bis 107 fachen Zn-Menge beschrieben. Das Cd wird zunächst als Komplex mit dem Anion der 0,0-Diäthyl-dithiophosphorsäure mittels CCl4 extrahiert. Dieser Komplex wird durch Zugabe von Dithizon unmittelbar in das Cd-Dithizonat umgewandelt, das photometriert wird.
Die Deutsche Forschungsgemeinschaft und der Verband der Chemischen Industrie unterstützten diese Arbeit durch Sachbeihilfen, wofür auch an dieser Stelle gedankt sei.
III. Mitt. [7]
Herrn Prof. Dr. W. Geilmann zum 75. Geburtstag gewidmet. 相似文献
Summary A method is described for the determination of micro-amounts of Cd in the presence of Zn, whose quantity is 105 to 107 times as large as the quantity of Cd. The Cd is first extracted with CCl4 as its complex with 0,0-diethyl-dithiophosphoric acid. This complex is directly converted into the Cd-dithizonate, whose colour intensity is measured.
Die Deutsche Forschungsgemeinschaft und der Verband der Chemischen Industrie unterstützten diese Arbeit durch Sachbeihilfen, wofür auch an dieser Stelle gedankt sei.
III. Mitt. [7]
Herrn Prof. Dr. W. Geilmann zum 75. Geburtstag gewidmet. 相似文献
105.
The electron density difference in a NaSCN crystal is set up from the ab initio densities of Na+ and SCN? ions and compared to the experimental counterpart based on X-ray diffraction measurements. Numerical integration over the electron density difference is executed around the Na+ ion. The atomic charge (+0.20e) derived in this way is in good agreement with the analogous experimental charge (+0.27e) The low experimental value cannot therefore be taken as an indication for a predominantly non-ionic structure of NaSCN and similar sodium salts 相似文献
106.
The half-sandwich type compounds C5H5Rh[P(OR)3]2 (R = CH3, C2H5, C6H5, p-CH3C6H4, p-ClC6H4) have been prepared from [(P(OR)3)2RhCl]2 and NaC5H5. The NMR. data as well as the IR. and mass spectra of the new compounds will be discussed. The preparation of C5H5Rh(CO)P(OC2H5)3 is also reported. 相似文献
107.
Hoebbel Dagobert Reinert Thomas Schmidt Helmut Arpac Ertugrul 《Journal of Sol-Gel Science and Technology》1997,10(2):115-126
The complexation degrees of Al-, Ti- and Zr-butoxide (M) with unsaturated and saturated -diketones (3-allylpentane-2.4-dione-APD, acetylacetone-ACAC) and -ketoesters (methacryloxyethyl-acetoacetate-MEAA, allylacetoacetate-AAA, ethylacetoacetate-EAA) as organic ligands (L) were examined by IR and 13 C NMR spectroscopy and were found to be L:M 1.5. The hydrolytic stability of the ligands of the metal alkoxide complexes (L:M = 1) during hydrolysis/condensation reactions at the molar ratio h (H2O : OR) = 0.5–2.0 decreases with increasing H
108.
Herber U Pechmann T Weberndörfer B Ilg K Werner H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(1):309-319
A series of dinuclear chelate complexes of the general composition [Rh2(kappa2-L)2(mu-CR2)2(mu-SbiPr3)] (R = Ph, p-Tol; L = CF3CO2-, acac-, acac-f3-) and [Rh2Cl(kappa2-L)(mu-CR2)2(mu-SbiPr3)] (R = Ph, p-Tol; L = acac-, acac-f3-) has been prepared by replacement of the chloro ligands in the precursors [Rh2Cl2(mu-CR2)2(mu-SbiPr3)] by anionic chelates. The lability of the SbiPr3 bridge in the rhodium dimers is illustrated by the reactions of [Rh2(kappa2-acac)2(mu-CR2)2(mu-SbiPr3)] (7, 8) with Lewis bases such as CO, CNtBu, and SbEt3 which lead to the formation of the substitution products [Rh2(kappa2-acac)2(mu-CR2)2(mu-L')] (13-16) in excellent yields. Treatment of 7 and 8 with sterically demanding tertiary phosphanes PR3 (R3 = iPr3, iPr2Ph, iPrPh2, Ph3) affords the mixed-valence Rh0-RhII complexes [(kappa2-acac)2Rh(mu-CPh2)2Rh(PR3)] (21-24) and [(kappa2-acac)2Rh(mu-C(p-Tol)2]2Rh(PiPr3)] (25) for which there is no precedence. The terminal PiPr3 ligand of 21 is easily displaced by alkynes, CNtBu, and CO to give, by preserving the [(kappa2-acac)2Rh(mu-CPh2)2Rh] molecular core, the related dinuclear compounds 26-31 in which the coordination number of the Rh0 center is 3, 4, or 5. The molecular structures of [Rh2Cl(kappa2-acac)(mu-CPh2)2(mu-SbiPr3)] (5), [Rh2(kappa2-acac)2(mu-CPh2)2(mu-CO)] (13), [(kappa2-acac)2Rh(mu-CPh2)2Rh(PiPr3)] (21), and [(kappa2-acac)2Rh(mu-CPh2)2Rh(CNtBu)2] (30) have been determined crystallographically. 相似文献
109.
We apply smoothing procedures to response functions for isoscalar vibrations. For collective motion, we find a transition from a structured strength distribution to one corresponding to one incoherent, strongly overdamped mode. It is argued that the latter may be interpreted as macroscopic motion exhibiting, to some extent, features of the hydrodynamical model. We discuss the physical origin of this behaviour, in particular its relation to the disappearance of shell structure.Supported in part by the Deutsche Forschungsgemeinschaft 相似文献
110.
Feth Martin P. Weber Achim Merkle Rotraut Reinöhl Ulrich Bertagnolli Helmut 《Journal of Sol-Gel Science and Technology》2003,27(2):193-204
Two solid solutions of lead zirconium titanates PbZr
x
Ti1 – x
O3 (x = 0.1 and 0.35) as well as the reference compounds lead titanate and lead zirconate were prepared from zirconium and titanium n-propoxide, dissolved in 2-methoxyethanol, by sol-gel process. The amorphous products after pyrolysis of the dried gels and the crystalline phases were studied by EXAFS spectroscopy to monitor the structural changes from the amorphous oxide mixture to the crystalline ceramics after calcination. Additionally, the crystalline phases were identified by X-ray diffraction (XRD).It follows from the analysis of the EXAFS data that the local order of the amorphous phases seems to be completely different from that of the crystalline phase. There is no indication of a preformation of the local order of the perovskite structure. The analysis of our EXAFS spectra can be interpreted very consistently with the assumption that in the amorphous samples a segregation exists on molecular level and the low crystallisation temperatures are a consequence of very short diffusion paths. 相似文献