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排序方式: 共有65条查询结果,搜索用时 31 毫秒
1.
Jiang Wei Dorthe Bagge Ravn Lone Gram Peter Kingshott 《Colloids and surfaces. B, Biointerfaces》2003,32(4):275-291
The surface of AISI 316 grade stainless steel (SS) was modified with a layer of poly(ethylene glycol) (PEG) (molecular weight 5000) with the aim of preventing protein adsorption and bacterial adhesion. Model SS substrates were first modified to introduce a very high density of reactive amine groups by the adsorption of branched poly(ethylenimine) (PEI) from water. Methoxy-terminated aldehyde-poly(ethylene glycol) (M-PEG-CHO) was then grafted onto the PEI layers using reductive amination at the lower critical solution temperature (LCST) of the PEG in order to optimize the graft density of the linear PEG chains. The chemical composition and uniformity of the surfaces were determined using X-ray photoelectron spectroscopy (XPS) and time-of-flight static secondary ion mass spectrometry (ToF-SSIMS) in the imaging mode. The effects of PEI concentration and different substrate pre-cleaning methods on the structure and stability of the final PEG layer was examined. Piranha solution proved to be the most effective method for removing adventitious hydrocarbon contamination, compared to cleaning with ultrasonication in organic solvents, and was the SS substrate that produced the most stable and thickest PEI layer. The surface density of PEI was shown to increase with increasing PEI concentration (up to 30 mg/ml), as determined from XPS measurements, and subsequently produced the PEG layer with the highest density of attached chains. In model experiments using β-lactoglobulin no protein adsorption was detected on the optimized PEG surface as determined by XPS and ToF-SSIMS analysis. However, neither the adhesion of a Gram-negative (Pseudomonas sp.) nor a Gram-positive (Listeria monocytogenes) bacterium was affected by the coating as equal numbers adhered to all surfaces tested. Our results show that preventing protein adsorption is not a prerequisite stopping bacterial adhesion, and that other mechanisms most likely play a role. 相似文献
2.
V. N. Fedoseyev Y. Jading O. C. Jonsson R. Kirchner K. -L. Kratz M. Krieg E. Kugler J. Lettry T. Mehren V. I. Mishin H. L. Ravn T. Rauscher F. Scheerer O. Tengblad P. Van Duppen A. Wöhr 《Zeitschrift für Physik A Hadrons and Nuclei》1995,353(1):9-10
The continuum part of the6Li (a,a)6Li (1.47–2.47 MeV) scattering data at Ea=50 MeV are extracted in two discretized bins. Coupled-channel calculations are carried out coupling the 1+ ground state of6Li with both the resonant, 3+
1 state, and two non-resonant continuum states. The discretized continuum of the6Li (p,p)6Li (1.75–3.25 MeV) scattering data at Ep=65 MeV are also analysed on the same footing. In both the cases the effect of coupling is found to be minimal. 相似文献
3.
4.
Ravn P Kjaer S Jensen KH Wind T Jensen KB Kristensen P Brosh RM Orren DK Bohr VA Clark BF 《Electrophoresis》2000,21(3):509-516
A procedure was established for selecting phage antibodies (phage-abs) from phage-displayed antibody repertoires by panning against proteins, separated by sodium dodecyl phosphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotted onto nitrocellulose membranes (Western blots). This immobilization strategy is applicable for secondary rounds of panning in selections against semipurified proteins, and directs the selection toward antibodies suitable as immunochemical reagents in Western blots. In model experiments, enrichment factors as high as 1.9x10(5) were obtained in a single round of panning. Furthermore, we demonstrate the application of this approach by selection of phage-abs recognizing the human Werner protein, which is defective in a premature aging syndrome. 相似文献
5.
A. Płochocki K. Rykaczewski T. Batsch J. Szerypo J. Żylicz R. Barden O. Klepper E. Roeckl D. Schardt H. Gabelmann P. Hill H. Ravn T. Thorsteinsen I. S. Grant H. Grawe P. Manakos L. D. Skouras 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(1):43-51
For the first time, detailed decay-spectroscopic investigations were performed for the very neutron-deficientN=50 nuclide98Cd. The98Cd activity was produced in spallation reactions between 600 MeV protons and a natural tin target, yielding a98Cd beam intensity of 10 to 60 atoms/s at the collector of the ISOLDE massseparator. By means of-ray and conversion-electron spectroscopy, 19 transitions were found to follow the +/EC decay98Cd98Ag. The transitions at 61 and 107 keV were shown to beM1(+E2) andE2, respectively, and the98Cd half-life was measured as 9.2±0.3 s. TheQ
EC value of98Cd is determined semiempirically and is compared to model predictions together with the measuredQ
EC values of the neighbouring cadmium isotopes100,102Cd and theN=50 isotones92Mo,94Ru, and96Pd, taken from the literature. The newly established decay scheme of98Cd includes 9 excited states of98Ag. Four states at 1691, 1861, 2164, and 2544 keV are directly fed by 0+ 1+ Gamow-Teller beta transitions with a summed strength of 3.5
–0.7
+0.8
. This value corresponds to 25±5% of the strength predicted for the GT transformation of a g9/2 proton (in98Cd) into a g7/2 neutron (in98Ag) by the extreme single-particle shell model. The GT-strength splitting and quenching, observed for98Cd, are compared with the corresponding data for lighter even-even N=50 isotones, and are discussed with reference to the predictions of more sophisticated nuclear models. We find that only in some cases it is possible to explain qualitatively the observed GT strength distribution and its total magnitude without renormalizing the free-neutron value of the axial-vector coupling constant.Dedicated to Prof. P. Armbruster on the occasion of his 60th birthday 相似文献
6.
JPC – Journal of Planar Chromatography – Modern TLC - Two simple and rapid methods for early detection of the effects of herbicides using two different groups of plant biomarkers are... 相似文献
7.
Shi Xunqing Wang Zhiping John HL Pang Zhang Xueren Nie Jingxu 《Acta Mechanica Sinica》2002,18(3):274-287
In this study, a new unified creep constitutive relation and a modified energy-based fatigue model have been established respectively
to describe the creep flow and predict the fatigue life of Sn−Pb solders. It is found that the relation successfully elucidates
the creep mechanism related to current constitutive relations. The model can be used to describe the temperature and frequency
dependent low cycle fatigue behavior of the solder. The relation and the model are further employed in part II to develop
the numerical simulation approach for the long-term reliability assessment of the plastic ball grid array (BGA) assembly.
The project supported by the National Natural Science Foundation of China (59705008) 相似文献
8.
Yun J Jespersen GR Kirsebom H Gustavsson PE Mattiasson B Galaev IY 《Journal of chromatography. A》2011,1218(32):5487-5497
A capillary-based model modified for characterization of monolithic cryogels is presented with key parameters like the pore size distribution, the tortuosity and the skeleton thickness employed for describing the porous structure characteristics of a cryogel matrix. Laminar flow, liquid dispersion and mass transfer in each capillary are considered and the model is solved numerically by the finite difference method. As examples, two poly(hydroxyethyl methacrylate) (pHEMA) based cryogel beds have been prepared by radical cryo-copolymerization of monomers and used to test the model. The axial dispersion behaviors, the pressure drop vs. flow rate performance as well as the non-adsorption breakthrough curves of different proteins, i.e., lysozyme, bovine serum albumin (BSA) and concanavalin A (Con A), at various flow velocities in the cryogel beds are measured experimentally. The lumped parameters in the model are determined by matching the model prediction with the experimental data. The results showed that for a given cryogel column, by using the model based on the physical properties of the cryogel (i.e., diameter, length, porosity, and permeability) together with the protein breakthrough curves one can obtain a reasonable estimate and detailed characterization of the porous structure properties of cryogel matrix, particularly regarding the number of capillaries, the capillary tortuousness, the pore size distribution and the skeleton thickness. The model is also effective with regards to predicting the flow performance and the non-adsorption breakthrough profiles of proteins at different flow velocities. It is thus expected to be applicable for characterizing the properties of cryogels and predicting the chromatographic performance under a given set of operating conditions. 相似文献
9.
C. Detraz M. Epherre D. Guillemaud P.G. Hansen B. Jonson R. Klapisch M. Langevin S. Mattsson F. Naulin G. Nyman A.M. Poskanzer H.L. Ravn M. de Saint-Simon K. Takahashi C. Thibault F. Touchard 《Physics letters. [Part B]》1980,94(3):307-309
Beta-delayed two-neutron emission from mass-separated samples of short-lived sodium isotopes has been detected both by n-n time correlations with a 4π neutron counter and by γ-spectroscopic identification of daughter products with mass A ? 2. The observed cases (intensities per beta decay) are . The results are in good agreement with a simple model of beta-particle emission. 相似文献
10.
J.M. Dauria J.W. Grüter E. Hagberg P.G. Hansen J.C. Hardy P. Hornsh?j B. Jonson S. Mattsson H.L. Ravn P. Tidemand-Petersson 《Nuclear Physics A》1978,301(3):397-410
Neutron-deficient caesium isotopes with mass numbers from 114 to 118 have been studied at the ISOLDE facility. Half-lives have been determined from counting of β-particles, β-delayed protons, and γ-rays. A short-lived isomer () in 116Cs has been observed and the new delayed-particle precursors 116Cs (protons and α-particles), 115Cs (protons), and 114Cs (protons and α-particles) have been identified. Coincidences between delayed particles and γ-rays have been measured for 118Cs (pγ and αγ) and 116Cs (pγ). A search for the possible proton-radioactive isotope 113Cs has been performed and an upper limit for its production yield is given. 相似文献