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排序方式: 共有57条查询结果,搜索用时 15 毫秒
1.
Stevenson NR Schubank RB Shin YM Amaudruz P Delheij PP Healey DC Jennings BK Ottewell DF Sheffer G Smith GR Wait GD Brack JT Feltham A Hanna M Johnson RR Rozon FM Sossi V Vetterli D Weber P Grion N Rui R Kohler M Ristinen RA Mathie EL Tacik R Yeomans M Gossett CA Wagner GJ 《Physical review letters》1990,65(16):1987-1990
2.
Proteomic analysis of the endoplasmic reticulum from developing and germinating seed of castor (Ricinus communis) 总被引:10,自引:0,他引:10
Endoplasmic reticulum (ER) has been prepared and analysed from germinating and developing castor bean endosperm. A combination of one- and two-dimensional (1-D and 2-D) gel electrophoresis was used to study the complexity of sample and protein differences between the two stages. The ER of the developing oilseed is central to the synthesis, sorting and storage of protein and lipid reserves while the germinating seed is concerned with their degradation. Sample complexity has been reduced by separation of ER proteins into lumenal, peripheral membrane and integral membrane subfractions. Membrane proteins pose specific problems in aggregation and binding to passive surfaces. We have overcome this by collection of membranes at density gradient interfaces and by silanization of plastic ware. Several major components have been identified from 1-D gels by N-terminal sequencing and matrix-assisted laser desorption/ionization (MALDI) peptide mass fingerprints. These include protein disulphide isomerase (PDI), calreticulin and developing-ER-specific oleate-12-hydroxylase involved in the biosynthesis of ricinoleic acid. In excess of 300 spots are detectable in each developmental fraction by high sensitivity 2-D gels. This is the first 2-D electrophoretic analysis of plant ER. These gels reveal significant differences between germinating and developing ER. Preparative loading 2-D gels of germinating ER have been run and 14 selected spots characterized by quadrupole time of flight tandem mass spectrometry (Q-TOF MS/MS). Ten of these proteins were assigned function on the basis of identity with existing castor database entries, or by homology with other species. Two proteins, aspartate proteinase precursor and N-carbamyl-L-aminohydrolase-like protein, appear to be absent from developing profiles. Most of the proteins identified are concerned with roles in protein processing and storage, and lipid metabolism which occur in the ER. Data from three of the assigned spots included unidentified peptides indicating the presence of more than one protein in these spots following 2-D electrophoresis. More extensive analysis will have to await developments in genomics but the basic separation technologies to simplify sample identity for a plant ER preparation have been established. 相似文献
3.
Two-dimensional protein map of human vastus lateralis muscle 总被引:4,自引:0,他引:4
Protein samples of human vastus lateralis muscle were analyzed by two-dimensional gel electrophoresis, using immobilized pH gradients encompassing several pH regions in the first dimension and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. More than 500 protein spots on each gel were detected by silver staining, of which 150 were excised, digested in-gel with trypsin and characterized by matrix assisted laser desorptioin/ionization-mass spectrometry and tandem electrospray mass spectrometry. Using these techniques, 124 spots including contractile proteins and metabolic enzymes were identified. This database should provide a valuable resource for the definition of the functional properties of muscle fibres and for assessment of the influence of e.g., hypoxia, ischaemia and ageing on protein level. 相似文献
4.
J. R. Wait 《Applied Scientific Research》1957,6(1):473-123
Summary A solution is outlined for the problem of an electric dipole which is located outside and parallel to the axis of a circular
cylinder fo infinite length. The corrugated surface of the cylinder is assumed to be described by an anisotropic boundary
impedance which specifies the ratios of the tangential electric and magnetic fields. It is shown that, in general, the radiated
field is elliptically polarized. 相似文献
5.
James R. Wait 《Applied Scientific Research》1958,7(1):73-80
Summary An expression for the mutual electromagnetic coupling between two small loops over a two-layer ground is derived. The result is expressed in a form which is suitable for calculation by a digital computer. When the heights or separation of the loops are large compared to the skin depth in the ground, simple asymptotic formulas for the fields can de developed. The results are employed to obtain a convenient formula for the self-impedance of a loop over a two-layer ground. 相似文献
6.
Impedance of an electric dipole located in a cylindrical cavity in a dissipative medium 总被引:1,自引:0,他引:1
The electromagnetic fields of an electric dipole located inside a cylindrical cavity or empty tunnel are formulated. The results
are used to deduce an expression for the change of self-impedance due to the presence of the cavity or tunnel walls. A numerical
evaluation of the resultant convergent integral and a summation of the angular harmonic series were performed. An important
finding is that the input resistance of the dipole is approximately a constant for frequencies less than about 25 MHz for
a typical tunnel radius of 2 m. Such results are shown to be in qualitative agreement with an earlier analysis of an electric
dipole over a dissipative half-space. 相似文献
7.
James R. Wait 《Applied Scientific Research》1954,3(1):230-236
Summary The problem of a small current-carrying loop situated over a thin plane sheet of conducting material is solved. The cases are considered where the loop axis is oriented both perpendicular and parallel to the plane of the sheet. 相似文献
8.
Using a transmission line theory, expressions for the propagation constant and characteristic impedance of a borehole antenna
are derived. Both air-filled and fluid-filled holes are considered. The required modal equation is solved by a rapidly convergent
iterative method. Some data for the input impedance and effective dipole moment for the terminated line are then provided.
It appears that the presence of conducting fluid in the hole will not seriously impair the effectiveness of the radiating
structure, but the voltage gradients in the insulation will be increased markedly. 相似文献
9.
10.
Summary Employing an approximate method the input impedance of a ground based vertical radiator is calculated. The ground system consists
of a number of radial conductors buried just below the surface of the soil. The integrals involved in the solution are evaluated,
in part, by graphical methods. The final results are plotted in a convenient form to illustrate the dependence of the impedance
on number and length of radial conductors for a specified frequency, antenna height, and ground conductivity. It is finally
shown that under usual conditions the radiated fields are modified by only a few percent due to the presence of the ground
system.
Work carried out under Project No. D 48-95-55-07. Paper presented at the U.S.A. National Convention of the Institute of Radio
Engineers in New York, March 1954. 相似文献