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81.
It has previously been shown that, in an electron-hole drop (EHD) produced in 〈11〉 -stressed Ge, a large population of electrons can be maintained in the strain-split-off (α3) electron valleys. The density and binding energy of these EHD are calculated on the assumption that the drops contain a single phase with a fixed ratio of α3 to α1 electrons. This ratio can be varied experimentally, and the observed densities as a function of α3 electron fraction are in good agreement with theory. 相似文献
82.
This paper develops the concept of a contour of complete nonuniqueness and shows its application to the optimal design (optimal layout) of simple trusses transmitting a concentrated force to a presscribed, arbitrary foundation contour. As an example, a symmetric two-bar truss with compressed bars is considered, and the constraints refer to various kinds of elastic instability of the system.Grant No. 05-12-10.2 of the Polish Academy of Sciences is gratefully acknowledged. 相似文献
83.
D. Czakis-Sulikowska J. Radwańska-Doczekalska M. Markiewicz 《Journal of Thermal Analysis and Calorimetry》2000,60(1):145-151
The mixed 2,4'-bipyridine-oxalato complexes of the formulae M(2,4'-bipy)2 C2 O4 2H2 O (M (II)=Mn, Co, Ni, Cu; 2,4'-bipyridine=2,4'-bipy or L ; C2 O2–
4 =ox) have been prepared and characterized. IR data show that the 2,4'-bipy coordinated with these metals(II) via the least
hindered (4')N atom; that oxalate group acts as bidentate chelating ligand. Room temperature magnetic moments are normal for
the orbital singlet states. The thermal decomposition of these complexes was investigated by TG, DTA and DTG in air. The endothermic
or exothermic character of the decomposition of ML2 (ox)2H2 O was discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
84.
D. Czakis-Sulikowska J. Radwańska-Doczekalska A. Czylkowska M. Markiewicz A. Broniarczyk 《Journal of Thermal Analysis and Calorimetry》2006,86(2):327-335
New mixed-ligand complexes with empirical
formulae: Mn(2-bpy)1.5L2·2H2O,
M(2-bpy)2L2·3H2O
(M(II)=Co, Cu), Ni(2-bpy)3L2·4H2O
and M(2,4’-bpy)2L2·2H2O
(where 2-bpy=2,2’-bipyridine, 2,4’-bpy=2,4’-bipyridine; L=HCOO– ) have been
obtained in pure solid-state. The complexes were characterized by chemical
and elemental analysis, IR and VIS spectroscopy, conductivity (in methanol
and dimethylsulfoxide). The way of metal-ligand coordination discussed. The
formate and 2,4’-bpy act as monodentate ligands and 2-bpy as chelate
ligand. The new complexes with ligand isomerism were identified. During heating
the complexes lose water molecules in one or two steps. Thermal decomposition
after dehydration is multistage and yields corresponding metal oxides as final
products. A coupled TG-MS system was used to analysis principal volatile thermal
decomposition (or fragmentation) products of Ni(2,4’-bpy)2(HCOO)2·2H2O under dynamic air or argon atmosphere. 相似文献
85.
We propose a new method for computing a large number of eigenpairs in the interior of the spectrum for conservative gyroscopic eigenproblems by the nonlinear Arnoldi method combined with a localized version of safeguarded iteration. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
86.
Nonlinear Dynamics of Floating Cranes 总被引:7,自引:0,他引:7
The nonlinear dynamic responses of moored crane vessels to regular wavesare investigated experimentally and theoretically. The main subject ofinterest are nonlinear phenomena like bifurcations and the existence ofmultiple attractors. In the experimental part of the work, a mooredmodel of a crane vessel has been excited by regular waves in a wavetank. A special mechanism has been developed to model the nonlinearbehavior of real mooring systems. The theoretical part of the workconcerns the mathematical modeling of the floating cranes. Twomathematical models of different levels of complexity are presented. Twodifferent tools are used to systematically determine the responses ofthe systems to periodic forcing of waves. Firstly, the path-followingtechniques in combination with numerical integration of equations ofmotion applied to a full nonlinear model give insight into the dynamicsin time domain. Secondly, the multiple scales method allows for ananalytical investigation of simplified nonlinear models in frequencydomain. Many results of computations for two crane vessels, barge andship, are presented. Special attention is paid to oscillations near thefrequencies of primary resonances and to subharmonic motions. Anexcellent agreement is found between the results of time-domain andfrequency-domain analysis. The computational examples chosen correspondto the models used not only in the present experiments but in theexperiments of others as well. The results presented in the work allow usto draw several important conclusions concerning the dynamic behavior offloating cranes during offshore operations. Both the developed modelsand the analytical tools can be used to identify the limits of theoperating range of floating cranes. 相似文献
87.
Esmanur lhan Pelin Poan Danuta Kruk Miosz Wojciechowski Maciej Osuch Roksana Markiewicz Stefan Jurga Mecit Halil Oztop 《Molecules (Basel, Switzerland)》2022,27(7)
Starch-based confectionery products were prepared using different types of sugar. In addition to using different sugar, starch was replaced with soy protein isolate (SPI) in some of the products. 1H NMR spin-lattice relaxation experiments were performed for the collection of products in a broad frequency range from 4 KHz to 30 MHz to get insight into the influence of different sugar types and SPI on the dynamics of water in composite gel systems. The relaxation data have been decomposed into relaxation contributions associated with two different pools of water molecules characterized by different mobility. The translation dynamics of water molecules has been quantitatively described in terms of a dedicated relaxation model. The influence of the sample composition (the type of sugar and/or the presence of SPI) on the water mobility was thoroughly discussed. The results indicate that the addition of soy protein does not affect water dynamics for samples including sucrose. In addition, as the complementary measurements, physical properties of the products, such as the moisture content, water activity and texture, were investigated in terms of X-ray diffraction and thermogravimetric analysis. 相似文献
88.
Waldemar Perdoch Zhuoran Cao Patryk Florczak Roksana Markiewicz Marcin Jarek Konrad Olejnik Bartomiej Mazela 《Molecules (Basel, Switzerland)》2022,27(15)
This article describes how crystalline or fibrous nanocellulose influences the mechanical properties of paper substrate. In this context, we used commercially available cellulose nanocrystals, mechanically prepared cellulose nanofibers dispersed in water or ethanol, and carboxy cellulose nanofibers. Selective reinforcement of the paper treated with the nanocellulose samples mentioned above was observed. The change in the fibre structure was assessed using scanning electron microscopy, roentgenography, and spectroscopy techniques. In addition, the effect of nanocellulose coating on physical properties was evaluated, specifically tensile index, elongation coefficient, Elmendorf tear resistance, Bendtsen surface roughness, Bendtsen air permeability, and bending strength. It can be concluded that the observed decrease in the strength properties of the paper after applying some NC compositions is due to the loss of potential disturbances in hydrogen bonds between the nanocellulose dispersed in ethanol and the paper substrate. On the other hand, significantly increased strength was observed in the case of paper reinforced with nanocellulose functionalized with carboxyl groups. 相似文献
89.
Katarzyna Markiewicz Anna Biak-Bieliska Paulina ukaszewicz Piotr Stepnowski Joanna Doonek 《Molecules (Basel, Switzerland)》2021,26(6)
Nowadays anticancer drugs (ADs), like other pharmaceuticals, are recognized as new emerging pollutants, meaning that they are not commonly monitored in the environment; however, they have great potential to enter the environment and cause adverse effects there. The current scientific literature highlights the problem of their presence in the aquatic environment by publishing more and more results on their analytics and ecotoxicological evaluation. In order to properly assess the risk associated with the presence of ADs in the environment, it is also necessary to investigate the processes that are important in understanding the environmental fate of these compounds. However, the state of knowledge on mobility of ADs in the environment is still very limited. Therefore, the main aim of our study was to investigate the sorption potential of two anticancer drugs, 5-fluorouracil (5-FU) and methotrexate (MTX), onto different soils. Special attention was paid to the determination of the influence of pH and ionic strength as well as presence of co-contaminants (cadmium (Cd2+) and another pharmaceutical—metoprolol (MET)) on the sorption of 5-FU and MTX onto soil. The obtained distribution coefficient values (Kd) ranged from 2.52 to 6.36 L·kg−1 and from 6.79 to 12.94 L·kg−1 for 5-FU and MTX, respectively. Investigated compounds may be classified as slightly or low mobile in the soil matrix (depending on soil). 5-FU may be recognized as more mobile in comparison to MET. It was proved that presence of other soil contaminants may strongly influence their mobility in soil structures. The investigated co-contaminant (MET) caused around 25-fold increased sorption of 5-FU, whereas diminished sorption of MTX. Moreover, the influence of environmental conditions such as pH and ionic strength on their sorption has been clearly demonstrated. 相似文献
90.
Practical Iron‐ and Cobalt‐Catalyzed Cross‐Coupling Reactions between N‐Heterocyclic Halides and Aryl or Heteroaryl Magnesium Reagents
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Dr. Olesya M. Kuzmina Dr. Andreas K. Steib M. Sc. Sarah Fernandez Willy Boudot Dr. John T. Markiewicz Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8242-8249
The reaction scope of iron‐ and cobalt‐catalyzed cross‐coupling reactions in the presence of isoquinoline (quinoline) in the solvent mixture tBuOMe/THF has been further investigated. Various 2‐halogenated pyridine, pyrimidine, and triazine derivatives were arylated under these mild conditions in excellent yields. The presence of isoquinoline allows us to perform Fe‐catalyzed cross‐coupling reactions between 6‐chloroquinoline and aryl magnesium reagents. Furthermore, it was found that the use of 10 % N,N‐dimethylquinoline‐8‐amine increases the yields of some Co‐catalyzed cross‐coupling reactions with chloropyridines bearing electron‐withdrawing substituents. 相似文献