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1.
J. J. Engelen S. J. de Jong M. Poletiek J. A. M. Vermaseren 《Zeitschrift fur Physik C Particles and Fields》1988,41(1):173-177
We present cross sections for heavy flavour production through photon gluon fusion in electron proton collisions at HERA energy. The electron photon vertex is taken into account explicitly, and theQ 2 of the exchanged photon ranges from nearly zero (almost real photon) to the kinematically allowed maximum. In our approach the scale is set by the mass of the produced quarks. Our formalism is also applicable to the production of light quarks as long as the invariant mass of the pair is sufficiently high, so we also give cross sections for \(u\bar u,d\bar d\) and \(s\bar s\) production. 相似文献
2.
In den Systemen FeSO3? H2O und NiSO3? H2O konnten folgende Hydrate erhalten werden: α-FeSO3 · 3H2O, γ-FeSO3 · 3H2O, FeSO3 · 2,5 H2O, FeSO3 · 2 H2O, NiSO3 · 6 H2O, NiSO3 · 3 H2O, NiSO3 · 2,5 H2O und NiSO3 · 2 H2O. Die Gitterdaten der folgenden Hydrate wurden anhand von Einkristallmessungen bestimmt: γ-FeSO3 · 3 H2O: a = 965,9(1), b = 557,1(1), c = 944,7(1) pm, Z = 4, FeSO3 · 2 H2O (P21/n): a = 645,6(1), b = 863,1(1), c = 761,2(1) pm, β = 99,84(1)°, Z = 4, NiSO3 · 3 H2O: a = 945,0(1), b = 547,2(1), c = 932,5(1) pm, Z = 4, NiSO3 · 2,5 H2O (P41212): a = b = 935,3(1), c = 1016,6(1) pm, Z = 8, NiSO3 · 2 H2O (P21/n): a = 631,4(1), b = 851,0(1), c = 744,7(1) pm, β = 98,91(1)°, Z = 4. Die IR- und Raman-Spektren sowie das Ergebnis thermoanalytischer Messungen (DTA, DTG, Röntgenheizaufnahmen) werden mitgeteilt. Die bei Sulfiten und Sulfithydraten zweiwertiger Metalle bisher beobachteten Strukturtypen werden diskutiert. Sulfites and Sulfite Hydrates of Iron and Nickel. X-ray, Thermoanalytical, I.R., and Raman Data In the systems FeSO3? H2O and NiSO3? H2O the following hydrates have been found: α-FeSO3 · 3H2O, γ-FeSO3 · 3H2O, FeSO3 · 2,5 H2O, FeSO3 · 2 H2O, NiSO3 · 6 H2O, NiSO3 · 3 H2O, NiSO3 · 2,5 H2O and NiSO3 · 2 H2O. The following crystal data have been determined by single crystal measurements: γ-FeSO3 · 3 H2O: a = 965,9(1), b = 557,1(1), c = 944,7(1) pm, Z = 4, FeSO3 · 2 H2O (P21/n): a = 645,6(1), b = 863,1(1), c = 761,2(1) pm, β = 99,84(1)°, Z = 4, NiSO3 · 3 H2O: a = 945,0(1), b = 547,2(1), c = 932,5(1) pm, Z = 4, NiSO3 · 2,5 H2O (P41212): a = b = 935,3(1), c = 1016,6(1) pm, Z = 8, NiSO3 · 2 H2O (P21/n): a = 631,4(1), b = 851,0(1), c = 744,7(1) pm, β = 98,91(1)°, Z = 4. IR, Raman, and thermoanalytical (DTA, DTG, high temperature X-ray) data are presented. The structure types found for sulfites and sulfite hydrates of bivalent metals are discussed. 相似文献
3.
NaM2OH(SO3)2 · 1 H2O with M = Mg, Mn, Fe, Co, Ni, and Zn. A New Class of Basic Sulfites Hitherto unknown hydroxide sulfites of the type NaM2OH(SO3)2 · 1 H2O with M = Mg, Mn, Fe, Co, Ni, and Zn have been obtained by crystallization from aqueous sulfite solutions containing Na+ and M2+ ions. Crystal structure, IR and Raman data, and the results of thermoanalytical studies are reported and discussed. The hydroxide sulfites show a strongly anisotropic thermal expansion due to the layer structure and exhibit an unusually high thermal stability compared to other solid hydrates. The magnesium compound, for example, decomposes at 355°C. The crystal data of the triclinic compounds see “Inhaltsübersicht”. 相似文献
4.
Carbaryl and its hydrolysis product, 1-naphthol, are determined simultaneously, and in a mixture of other pesticides, by reversed-phase high-performance liquid chromatography (HPLC). Fluorometric detection affords a higher degree of selectivity than absorbance detection, while providing detection limits of 1.0 ng ml(-1) and 1.4 mg ml(-1) for 1-naphthol and carbaryl, respectively. The described method requires no enrichment of samples and includes a simple hydrolysis step. Additionally, enhancement of fluorescence detection signal intensity is explored through HPLC solvent composition effects as well as through formation of cyclodextrin inclusion complexes. The method described in this report is a selective and fast alternative to the currently accepted U.S. Environmental Protection Agency (EPA) method of detection carbaryl in ground water. 相似文献
5.
6.
Maj-Britt Schmidt Andersen Mette Kristensen Claudine Manach Estelle Pujos-Guillot Sanne Kellebjerg Poulsen Thomas Meinert Larsen Arne Astrup Lars Dragsted 《Analytical and bioanalytical chemistry》2014,406(7):1829-1844
While metabolomics is increasingly used to investigate the food metabolome and identify new markers of food exposure, limited attention has been given to the validation of such markers. The main objectives of the present study were to (1) discover potential food exposure markers (PEMs) for a range of plant foods in a study setting with a mixed dietary background and (2) validate PEMs found in a previous meal study. Three-day weighed dietary records and 24-h urine samples were collected three times during a 6-month parallel intervention study from 107 subjects randomized to two distinct dietary patterns. An untargeted UPLC-qTOF-MS metabolomics analysis was performed on the urine samples, and all features detected underwent strict data analyses, including an iterative paired t test and sensitivity and specificity analyses for foods. A total of 22 unique PEMs were identified that covered 7 out of 40 investigated food groups (strawberry, cabbages, beetroot, walnut, citrus, green beans and chocolate). The PEMs reflected foods with a distinct composition rather than foods eaten more frequently or in larger amounts. We found that 23 % of the PEMs found in a previous meal study were also valid in the present intervention study. The study demonstrates that it is possible to discover and validate PEMs for several foods and food classes in an intervention study with a mixed dietary background, despite the large variability in such a dataset. Final validation of PEMs for intake of foods should be performed by quantitative analysis. Figure
Examples of two urinary exposure markers for cabbage (left) and beetroot (right) found in the study from an untargeted LC‐MS metabolomics analysis of urine samples and self‐reported food intake data 相似文献
7.
Ph. Gavillet C. Dionisi A. Gurtu R.J. Hemingway M.J. Losty J.C. Marin M. Mazzucato L. Montanet E. Pagiola R. Blokzijl B. Jongejans J.C. Kluyver G.G.G. Massaro J.J. Engelen J.S.M. Vergeest M. Zralek B. Foster P. Grossmann J. Wells 《Physics letters. [Part B]》1978,78(1):158-161
The backward production of the B(1235) meson is studied in the reaction K?p→Σ?π+ω. This reaction is observed in the final state Σ?π+π+π?π0. A π+ω mass enhancement is visible in the region of the B meson for events with small |u|K? →Σ?) squared four-momentum transfer. The properties of the enhancement agree with those of the B meson. The cross section for K?p→Σ?B+ at incident K? momentum is (3.2 ± 0.5) μb. The backward production of the B meson is compared with similar baryon exchange productions of the A1 and C(Q1) axial vector mesons observed in the same experiment. 相似文献
8.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献
9.
10.
In this paper we consider the Cumulative Capacitated Vehicle Routing Problem (CCVRP), which is a variation of the well-known Capacitated Vehicle Routing Problem (CVRP). In this problem, the traditional objective of minimizing total distance or time traveled by the vehicles is replaced by minimizing the sum of arrival times at the customers. We propose a branch-and-cut-and-price algorithm for obtaining optimal solutions to the problem. To the best of our knowledge, this is the first published exact algorithm for the CCVRP. We present computational results based on a set of standard CVRP benchmarks and investigate the effect of modifying the number of vehicles available. 相似文献