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111.
Martano G Vogl C Bojaxhi E Bresgen N Eckl P Stutz H 《Analytical and bioanalytical chemistry》2011,400(8):2415-2426
A validated method for the simultaneous determination of prominent volatile cleavage products (CPs) of β-carotene in cell
culture media has been developed. Target CPs comprised β-ionone (β-IO), cyclocitral (CC), dihydroactinidiolide (DHA), and
1,1,6-trimethyltetraline (TMT). CPs were extracted by solid-phase extraction applying a phenyl adsorbent, eluted with 10%
(v/v) tetrahydrofuran in n-hexane, and identified and quantified by gas chromatography-mass spectrometry with electron impact ionization. Method validation
addressed linearity confirmation over two application ranges and homoscedasticity testing. Recoveries from culture media were
between 71.7% and 95.7% at 1.0 μg/ml. Precision of recoveries determined in intra-day (N = 5) and inter-day (N = 15) assays were <2.0% and <4.8%, respectively. Limit of detection and limit of quantification of the analysis method were
<18.0 and <53.0 ng/ml for β-IO, CC, and TMT, whereas 156 and 474 ng/ml were determined for DHA, respectively. Although extractions
of blank matrix proved the absence of interfering peaks, statistical comparison between slopes determined for instrumental
and total method linearity revealed significant differences. The method was successfully applied in selecting an appropriate
solvent for the fortification of culture media with volatile CPs, including the determination of their availability over the
incubation period. For the first time, quantification of volatile CPs in treatment solutions and culture media for primary
cells becomes accessible by this validated method. 相似文献
112.
Barbazanges M Augé M Moussa J Amouri H Aubert C Desmarets C Fensterbank L Gandon V Malacria M Ollivier C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(49):13789-13794
Enantioenriched bicyclo[4.1.0]hept-2-enes were synthesized by Ir(I)-catalyzed carbocyclization of 1,6-enynes. No chiral ligands were used, CO and PPh(3) were the only ligands bound to iridium. Instead, the stereochemical information was localized on the counterion of the catalyst, generated in situ by reaction of Vaska's complex (trans-[IrCl(CO)(PPh(3))(2)]) with a chiral silver phosphate. Enantiomeric excesses up to 93% were obtained when this catalytic mixture was used. (31)P NMR and IR spectroscopy suggest that formation of the trans- [Ir(CO)(PPh(3))(2)](+) moiety occurs by chlorine abstraction. Moreover, density functional theory calculations support a 6-endo-dig cyclization promoted by this cationic moiety. The chiral phosphate anion (O-P*) controls the enantioselectivity through formation of a loose ion pair with the metal center and establishes a C-H···O-P* hydrogen bond with the substrate. This is a rare example of asymmetric counterion-directed transition-metal catalysis and represents the first application of such a strategy to a C-C bond-forming reaction. 相似文献
113.
Vogl J 《Rapid communications in mass spectrometry : RCM》2012,26(3):275-281
Triple IDMS has been applied for the first time to the quantification of element concentrations. It has been compared with single and double IDMS obtained on the same sample set in order to evaluate the advantages and disadvantages of triple IDMS over single and double IDMS as an analytical reference procedure. The measurement results of single, double and triple IDMS are indistinguishable, considering rounding due to the individual measurement uncertainties. As expected, the relative expanded uncertainties (k = 2) achieved with double IDMS (0.08 %) are dramatically smaller than those obtained with single IDMS (1.4 %). Triple IDMS yields the smallest relative expanded uncertainties (k = 2, 0.077 %) unfortunately at the expense of a much higher workload. Nevertheless triple IDMS has the huge advantage that the isotope ratio of the spike does not need to be determined. Elements with high memory effects, highly enriched spikes or highest metrological requirements may be typical applications for triple IDMS. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
114.
Nour-Eldin NE Abdelmonem O Tawfik AM Naguib NN Klingebiel T Rolle U Schwabe D Harth M Eltoukhy MM Vogl TJ 《Magnetic resonance imaging》2012,30(7):893-906
Magnetic resonance imaging (MRI) has become one of the most valuable modalities for initial and follow-up imaging of suspected or known neuroblastoma (NBL) owing to its excellent inherent contrast, lack of ionizing radiation and multiplanar imaging capability. Importantly, NBL has a variable appearance on different imaging modalities, and this is particularly pertinent to MRI. MRI is a cornerstone for management of NBL, providing essential information at initial presentation regarding diagnosis, staging, resectability and relation to vital structures. It can also define the extent of residual disease after surgical resection or assess the efficacy of treatment. Follow-up MRI is frequently performed to ensure sustained complete remission or to monitor known residual disease. This pictorial review article aims to provide the reader with a concise, yet comprehensive, collection of MR images of primary and metastatic NBL lesions with relevant correlation with other imaging modalities. 相似文献
115.
116.
Aug Vogel 《Fresenius' Journal of Analytical Chemistry》1884,23(1):536-537
Ohne Zusammenfassung 相似文献
117.
118.
The copolymerization of 3,4-dimethyltetrahydrofuran with selected cyclic ethers was studied. Although 3,4-dimethyltetrahydrofuran did not homopolymerize, it readily copolymerized with propylene oxide and epichlorohydrin in an alternating fashion using the cationic initiator PF5. The reactivity ratios r1 and r2 for the copolymerization of 3, 4-dimethyltetrahydrofuran and epichlorohydrin were r1 = 0.22 ± 0.05 and r2 = 0.11 ± 0.01, respectively. 相似文献
119.
Kubisa P. und O. Vogl 《Colloid and polymer science》1977,255(7):723
Ohne Zusammenfassung 相似文献
120.
B.A. Cruz-Vidal G. Wehr K. Böning G. Vogl 《Journal of Physics and Chemistry of Solids》1973,34(8):1335-1342
Four KBr single crystals were irradiated at 4·6°K in the core of the Munich Nuclear Reactor for periods of 100 sec, 10 min or 1 hr, respectively. After irradiation the stored energy of the samples was measured in a differential-heat-flow calorimeter at heating rates of 0·29°K/min and 1·1°K/min. At 0·29°K/min peaks of stored energy release were resolved near 11 and 20°K and at 25, 38 and 45°K. An attempt was made to evaluate the corresponding activation energies using two different methods (see Table 1 in the text). The 25°K annealing stage is due to a first order recombination reaction. The anneling states near 20, at 38 and at 45°K do not correspond to first order reactions. Our results are compared with annealing studies on low temperature X-irradiated KBr crystals. A similar experiment was performed on KCl single crystals and is reported, together with a more detailed comparison and discussion of both experiments, in a later paper[14]. 相似文献