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1.
Thermal and epithermal neutron activation analysis has been applied to determine the concentrations of magnesium, aluminium, phosphorus, copper and manganese in two biological fluids: blood serum and market milk. Both epithermal neutron irradiation and radiochemical separation (a chromatographic column of HAP) were used to get rid of the interferences from 24-Na. Strongly acidic solutions of the irradiated samples were passed through the columns of HAP, where sodium was completely adsorbed while, Al, Cu, Mg and Mn were eluted with an efficiency of 99±1%. Since both Al and P were determined through the formation of28Al (2.24 min) thermal and epithermal neutron activation have been applied in order to determine the contribution of each radionuclide to28Al activity. The determination of Mg, Al and P in milk samples was done instrumentally, whereas in the case of blood serum with higher concentration of Na, a radiochemical separation is essential in both cases. The concentrations of Al, Cu, Mg, Mn and P in blood serum and market milk were found to be 0.24±0.02 and 1.85±0.09 g Al/ml, 1.35±0.04 and 0.068±0.005 g Cu/ml, 22.9±1 and 98.9±8.6 g Mg/ml, 22±3 and 16±2 ng Mn/ml and 167±13 and 865±32 g P/ml, respectively. 相似文献
2.
Theoretical and experimental study of the adsorption on radioactive gases on continuous flow columns
A bimolecular reaction model was used to describe the adsorption process in continuous flow columns filled with solid adsorbents. The analytical solution of the model for low gas concentrations and a cascade-type numerical method for higher gas concentrations were developed. An air flow apparatus using activated carbon as adsorbent and methyl-iodide labelled with125I as adsorbate was constructed for measuring breakthrough- and accumulation curves. 相似文献
3.
Photodynamic therapy removes unwanted or harmful cells by overproduction of reactive oxygen species (ROS). Fractionated light delivery in photodynamic therapy may enhance the photodynamic effect in tumor areas with insufficient blood supply by enabling the reoxygenation of the treated area. This study addresses the outcome of fractionated irradiation in an in vitro photodynamic treatment (PDT) system, where deoxygenation can be neglected. Our results show that fractionated irradiation with light/dark intervals of 45/60 s decreases ROS production and cytotoxicity of PDT. This effect can be reversed by addition of 1,3-bis-(2-chlorethyl)-1-nitrosurea (BCNU), an inhibitor of the glutathione reductase. We suggest that the dark intervals during irradiation allow the glutathione reductase to regenerate reduced glutathione (GSH), thereby rendering cells less susceptible to ROS produced by PDT compared with continuous irradiation. Our results could be of particular clinical importance for photodynamic therapy applied to well-oxygenated tumors. 相似文献
4.
Summary Chirally substituted Si–H-containing polysiloxanes were synthesized, which can be immobilized on small particle silica gel as well as on the smooth surfaces of fused silica capillaries. Immobilization is achieved either by crosslinking or by chemical bonding to the surfaces via silanol groups; both reactions can only be performed by addition of H2PtCl6, which acts as catalyst for hydrosilylation and as stoichiometric reagent for crosslinking. Chiral substituents of systematically varied chemical structure were introduced into the polysiloxanes by hydrosilylation. The mechanism of immobilization was investigated by spectroscopic methods, notably29Si-NMR. Homogenous stationary-phase coatings of variable film thickness and corresponding retentivity can easily be achieved. The enantioselectivity of the phase systems was characterized in dependency on the chemical structure of the chiral selectors attached to the polysiloxane chain of the chiral stationary phases and also in terms of the functional groups introduced into the solutes by derivatisation. 相似文献
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7.
R. Chulkov V. Lisinetskii O. Lux H. Rhee S. Schrader H. J. Eichler V. Orlovich 《Applied physics. B, Lasers and optics》2012,106(4):867-875
Raman frequency conversion of high average power pulsed Nd:YAG laser radiation into the near IR spectral region in a barium
nitrate Raman laser was studied with the emphasis on thermal effects inside the Raman-active medium. The probe-beam technique
together with numerical reconstruction, done by integrating the transient heat conduction and paraxial wave equations, revealed
dynamics of the induced distortions featuring high-order optical aberrations. By utilizing the Zernike expansion of the reconstructed
phase profile and implementing a special focusing geometry of the pump beam, partial compensation of the distortions was realized
in a stable configuration of the Raman cavity. Generation of the first-, second-, and third-order Stokes radiation with output
power of 17, 9.5, and 5.5 W corresponding to a quantum conversion efficiency of 32, 21, and 13% is reported. 相似文献
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9.
U. Stolzenburg T. Lux 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(4):521-533
Processes of social opinion formation might be dominated by a set of closely connected
agents who constitute the cohesive ‘core’ of a network and have a higher influence on the
overall outcome of the process than those agents in the more sparsely connected
‘periphery’. Here we explore whether such a perspective could shed light on the dynamics
of a well known economic sentiment index. To this end, we hypothesize that the respondents
of the survey under investigation form a core-periphery network, and we identify those
agents that define the core (in a discrete setting) or the proximity of each agent to the
core (in a continuous setting). As it turns out, there is significant correlation between
the so identified cores of different survey questions. Both the discrete and the
continuous cores allow an almost perfect replication of the original series with a reduced
data set of core members or weighted entries according to core proximity. Using a monthly
time series on industrial production in Germany, we also compared experts’ predictions
with the real economic development. The core members identified in the discrete setting
showed significantly better prediction capabilities than those agents assigned to the
periphery of the network. 相似文献
10.
Jerzy Lewandowski Pawel Nurowski Marek A. Abramowicz Benno Artmann Sherman K. Stein 《Mathematical Intelligencer》2000,22(3):3-4
The Mathematical Intelligencer encourages comments about the material in this issue. Letters to the editor should be sent
to the editor-in-chieX Chandler Davis. 相似文献