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排序方式: 共有758条查询结果,搜索用时 703 毫秒
751.
752.
MJ Yoo TA Fulton HF Hess RL Willett LN Dunkleberger RJ Chichester LN Pfeiffer KW West 《Science (New York, N.Y.)》1997,276(5312):579-582
A single-electron transistor scanning electrometer (SETSE)-a scanned probe microscope capable of mapping static electric fields and charges with 100-nanometer spatial resolution and a charge sensitivity of a small fraction of an electron-has been developed. The active sensing element of the SETSE, a single-electron transistor fabricated at the end of a sharp glass tip, is scanned in close proximity across the sample surface. Images of the surface electric fields of a GaAs/AlxGa1-xAs heterostructure sample show individual photo-ionized charge sites and fluctuations in the dopant and surface-charge distribution on a length scale of 100 nanometers. The SETSE has been used to image and measure depleted regions, local capacitance, band bending, and contact potentials at submicrometer length scales on the surface of this semiconductor sample. 相似文献
753.
M Crawford 《Science (New York, N.Y.)》1987,235(4795):1454-1455
754.
Nene V Wortman JR Lawson D Haas B Kodira C Tu ZJ Loftus B Xi Z Megy K Grabherr M Ren Q Zdobnov EM Lobo NF Campbell KS Brown SE Bonaldo MF Zhu J Sinkins SP Hogenkamp DG Amedeo P Arensburger P Atkinson PW Bidwell S Biedler J Birney E Bruggner RV Costas J Coy MR Crabtree J Crawford M Debruyn B Decaprio D Eiglmeier K Eisenstadt E El-Dorry H Gelbart WM Gomes SL Hammond M Hannick LI Hogan JR Holmes MH Jaffe D Johnston JS Kennedy RC Koo H Kravitz S Kriventseva EV Kulp D Labutti K Lee E Li S Lovin DD 《Science (New York, N.Y.)》2007,316(5832):1718-1723
We present a draft sequence of the genome of Aedes aegypti, the primary vector for yellow fever and dengue fever, which at approximately 1376 million base pairs is about 5 times the size of the genome of the malaria vector Anopheles gambiae. Nearly 50% of the Ae. aegypti genome consists of transposable elements. These contribute to a factor of approximately 4 to 6 increase in average gene length and in sizes of intergenic regions relative to An. gambiae and Drosophila melanogaster. Nonetheless, chromosomal synteny is generally maintained among all three insects, although conservation of orthologous gene order is higher (by a factor of approximately 2) between the mosquito species than between either of them and the fruit fly. An increase in genes encoding odorant binding, cytochrome P450, and cuticle domains relative to An. gambiae suggests that members of these protein families underpin some of the biological differences between the two mosquito species. 相似文献
755.
Bertram TH Perring AE Wooldridge PJ Crounse JD Kwan AJ Wennberg PO Scheuer E Dibb J Avery M Sachse G Vay SA Crawford JH McNaughton CS Clarke A Pickering KE Fuelberg H Huey G Blake DR Singh HB Hall SR Shetter RE Fried A Heikes BG Cohen RC 《Science (New York, N.Y.)》2007,315(5813):816-820
We present a statistical representation of the aggregate effects of deep convection on the chemistry and dynamics of the upper troposphere (UT) based on direct aircraft observations of the chemical composition of the UT over the eastern United States and Canada during summer. These measurements provide unique observational constraints on the chemistry occurring downwind of convection and the rate at which air in the UT is recycled. These results provide quantitative measures that can be used to evaluate global climate and chemistry models. 相似文献
756.
Crawford M 《Science (New York, N.Y.)》1985,229(4720):1373
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