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1.
We present a detailed derivation of the fluctuation transport theory, previously developed by Gerlach and Mycielski. The basic idea is the transformation of carrier-densities and fields into the rest frame of each type of carriers and application of the Fluctuation-Dissipation-theorem for monopolar, unscreened carrier densities. In the present paper, the theory is applied to a model system containing free electrons, rigid ions and polarizable neutral donors. We compare our results with experimental data for the polar II–VI-semiconductor Eu1-xSrxS. 相似文献
2.
The major goal of this paper is to examine the hypothesis that stock returns and return volatility are asymmetric, threshold nonlinear, functions of change in trading volume. A minor goal is to examine whether return spillover effects also display such asymmetry. Employing a double-threshold GARCH model with trading volume as a threshold variable, we find strong evidence supporting this hypothesis in five international market return series. Asymmetric causality tests lend further support to our trading volume threshold model and conclusions. Specifically, an increase in volume is positively associated, while decreasing volume is negatively associated, with the major price index in four of the five markets. The volatility of each series also displays an asymmetric reaction, four of the markets display higher volatility following increases in trading volume. Using posterior odds ratio, the proposed threshold model is strongly favored in three of the five markets, compared to a US news double threshold GARCH model and a symmetric GARCH model. We also find significant nonlinear asymmetric return spillover effects from the US market. 相似文献
3.
4.
S. Herrmann W. Vonau F. Gerlach H. Kaden 《Analytical and bioanalytical chemistry》1998,362(2):215-217
A new sensor module is developed for the in-situ control of waters, especially surface waters. Complex miniaturized sensor technology is used for the determination of the parameters pO2, pH, pNO3, pCl, pPO4, pNH3 or pNH4 and conductivity. Miniaturization of sensors results in small sample volumes and small volumes of calibration solution required. Results of testing this sensor module are described. The special features of this apparatus are its compact construction and its optimum functioning capability under flow conditions. 相似文献
5.
I. Halász H. O. Gerlach A. Kroneisen und P. Walkling 《Fresenius' Journal of Analytical Chemistry》1968,234(2):97-108
Zusammenfassung Die Bandenverbreiterung in der Flüssigkeits-Chromatographie, verursacht durch Kolonne, Kolonnenzuleitungen und Detektor, wurde untersucht durch Messung von h-u-Kurven bis zu Kolonneneingangsdrucken von 15 at. Die Einflüsse außerhalb der Kolonne konnten durch eine besondere Formgebung der entsprechenden Bauelemente vermindert werden. Aromatische N-Verbindungen wurden an einer Silicagel-Kolonne getrennt, wobei etwa 1 effektiver Boden pro Sekunde erzielt werden konnte.
Symbolverzeichnis at 1 Kilopond/cm2 Druck - h Bandenverbreiterung in der Kolonne oder HETP [cm] - h exp L(w/4t R)2 = experimentell bestimmte h-Werte - k Verteilungskoeffizient [-] - k = t R/t0 Massenverteilungsverhältnis [-] - t 0 Durchbruchszeit der Inertbande [sec] - t R Retentionszeit [sec] - t R t r-t0 = Reduzierte Retentionszeit [sec] - u Lineare Geschwindigkeit der mobilen Phase [cm · sec–1] - w Bandenbreite, Achsenschnitt der Wendetangenten an der Basislinie [sec] - C Massentransportkoeffizient der van Deemter-Gleichung [sec] - L Länge der Kolonne [cm] - N (4t R/w)2 = effektive Bandenschärfe oder effektive Bodenzahl - V m Volumen der mobilen Phase in der Kolonne [cm3] - V s Volumen der stationären Phase in der Kolonne [cm3] Die Autoren bedanken sich bei der Deutschen Forschungsgemeinschaft, Bad Godesberg, mit deren finanzieller Unterstützung diese Arbeit ausgeführt wurde. 相似文献
Summary Peak broadening effects in liquid chromatography inside and outside the column, i.e. the influence of the column, the connection and the detector were studied, determining experimentaly h vs. u curves up to 15 at. inlet pressure. Geometry for both of the latter is proposed to diminish peak broadening outside the column. Aromatic N-compounds are resolved on silicagel producing about 1 effective plate per second.
Symbolverzeichnis at 1 Kilopond/cm2 Druck - h Bandenverbreiterung in der Kolonne oder HETP [cm] - h exp L(w/4t R)2 = experimentell bestimmte h-Werte - k Verteilungskoeffizient [-] - k = t R/t0 Massenverteilungsverhältnis [-] - t 0 Durchbruchszeit der Inertbande [sec] - t R Retentionszeit [sec] - t R t r-t0 = Reduzierte Retentionszeit [sec] - u Lineare Geschwindigkeit der mobilen Phase [cm · sec–1] - w Bandenbreite, Achsenschnitt der Wendetangenten an der Basislinie [sec] - C Massentransportkoeffizient der van Deemter-Gleichung [sec] - L Länge der Kolonne [cm] - N (4t R/w)2 = effektive Bandenschärfe oder effektive Bodenzahl - V m Volumen der mobilen Phase in der Kolonne [cm3] - V s Volumen der stationären Phase in der Kolonne [cm3] Die Autoren bedanken sich bei der Deutschen Forschungsgemeinschaft, Bad Godesberg, mit deren finanzieller Unterstützung diese Arbeit ausgeführt wurde. 相似文献
6.
The conditions, under which in aqueous solution CuII ist reduced by FeII, are discussed. The conditions for the formation of Cu2O and metallic Cu, respectively, are determined by means of potentiometric measurements and other experiments. 相似文献
7.
8.
Hans Gerlach 《Helvetica chimica acta》1985,68(7):1815-1821
Determination of the Chirality Sense of the Enantiomeric 2,6-Adamantanediols The enantiomers of 2,6-adamantanediol ( 1 ) are resolved via the diastereoisomeric camphanoates. The (2R,6R)-chirality sense for (?)- 1 and (2S,6S) for (+)- 1 was determined by chemical correlation with (?)-(1R,5R)-bicyclo[3.3.1]nonan-2,6-dion ((1R,5R)- 3 ) of known absolute configuration in the following way: alkylation of the bis(pyrrolidine enamine) of (?)-(1R,5R)- 3 with CD2I2 and hydrolysis of the product gives the enantiomer 4 of (4,4-D2)-2,6-adamantanedione. Reduction of 4 with LiAlH4 leads to one enantiomer (Scheme 2) of each of the three diols 5 – 7 of known absolute configuration. The three diols are themselves configurational isomers due to the presence of the CD2 group, but correspond otherwise entirely to the enantiomeric diols 1 . Accordingly, they can also be separated by means of their diastereoisomeric camphanoates to give the diols 5 / 6 and 7 . These samples are easily distinguished and identified by their characteristic 1H-NMR spectra (cf. Fig. 2). This allows to identify the (2R,6R)- and (2S,6S)-enantiomer of 1 on the basis of their behavior in the resolution experiment analogous to that of the diols 5 / 6 and 7 , respectively. The diol (?)- 1 must have the (2R,6R)-configuration because it forms, like the diols 5 / 6 , with (?)-camphanic acid the diastereoisomeric ester less soluble in benzene. The diol (+)- 1 has (2S,6S)-configuration, because it forms, like 7 , with (+)-camphanic acid the diastereoisomeric ester less soluble in benzene. The bis(4-methoxybenzoate) of (?)-(2R,6R)- 1 shows chiroptical properties which are in accordance with Nakanishi's rule for two chromophores having coupled electric dipol transition moments arranged with a left-handed torsion angle. 相似文献
9.
Synthesis of Dysidin The synthesis of dysidin ((?)- 1 ), the enantiomer of a metabolite of the marine sponge Dysidea herbacea, is described. To effect the synthesis, (±)-5-isopropyl-4-methoxy-3-pyrrolin-2-one ( 7 ) is converted to its lithium salt and reacted with (?)-(5R,2E)-3-methoxy-5-trichloromethyl-2-hexenoyl chloride ((-)- 11 ) to give (?)- 1 and its diastereoisomer (+)-5-epidysidin ((+)- 12 ) epimeric at C(5) of the pyrrolinone ring. The (?)-acyl chloride (?)- 11 has been synthesized from (+)-(R)-3-(trichloromethyl)butanoic acid ((+)- 8 ) via the intermediates (+)- 9 and (?)- 10 , the pyrrolinone 7 from N-benzyl-oxycarbonyl-L-valine via the intermediate 5 . The enantiomers of acid 8 have been resolved by fractional crystallization of their diastereoisomeric N-(1-phenylethyl)amides. The (R)-chirality of (+)- 8 was determined by comparing the 1H-NMR spectra of the diastereoisomeric N-(1-phenylethyl)amides 16 and 17 , made from (+)- 8 by substituting deuterium for chlorine, with the spectra of the N-(1-phenylethyl)amides 14 and 15 of known absolute configuration. This correlation shows that literature value (R) for (?)- 8 is in error. Therefore, the structural formulae of (?)-dysidenin and (+)-isodysidenin, two other metabolites of D.herbacea, have to be changed to their mirror images as shown in formulae (?)- 3 and (+)- 4 , respectively. 相似文献
10.
A barrier to routine application of anodic stripping voltammetry is the possible formation of intermetallic compounds which can lead to significant errors in the estimated analyte concentrations. As the method of standard additions can correct only for matrix effects, it is powerless to correct for intermetallic interferences which are not matrix effects. By changing the experimental design, the new generalized standard addition method can simultaneously characterize and correct for this type of interference as well as matrix effects expected for real samples. The method is tested on the Cu—Zn—Hg system and error estimates are provided for calculated linear response constants and analyte concentration. 相似文献