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21.
P M Fitzgerald A H Wang A McPherson F A Jurnak I Molineux F Kolpak A Rich 《Journal of supramolecular structure》1979,10(4):479-489
Complexes of the gene 5 protein from bacteriophage fd with a variety of oligodeoxynucleotides, ranging in length from two to eight and comprised of several different sequences, have been formed and crystallized for X-ray diffraction analysis. The crystallographic parameters of four different unit cells, all of which are based on hexagonal packing arrangements, indicate that the fundamental unit of the complex is composed of six gene 5 protein dimers. We believe this aggregate has 622 point group symmetry and is a ring formed by end-to-end closure of a linear array of six dimers. From our results we have proposed a double-helix model for the gene 5 protein-DNA complex in which the protein forms a spindle or core around which the DNA is spooled. Currently 5.0-A X-ray diffraction data from one of the crystalline complexes is being analyzed by molecular replacement techniques to obtain a direct image of the protein-nucleic acid complex. 相似文献
22.
A modeling tool is presented that allows a complete analysis of a DC stress experiment without assuming the location and amount of trapped oxide charges and interface states. To describe the buildup of oxide damage, a semiempirical rate equation approach is outlined. A completely self-consistent calculation is presented of the time dependence of the DC stress experiment. This calculation monitors the amount and location of charges built up in the 2-D oxide region during the stress line. The model includes competing trap mechanisms such as the formation of interface states and fixed oxide traps. This permits consideration of n- and p-channel MOSFETs with the same model. The calculations are compared to DC stress measurements on n- and p-channel devices with gate lengths of 0.65 μm that are typical for 16-Mb DRAMs 相似文献
23.
24.
An experiment is discussed in which CO can be excited up to energies of several electronvolts by the absorption of infrared radiation from a relatively low-power CO laser. Furthermore, experimental results are examined through kinetic modelling. In the experiment, the beam of an intracavity-chopped CO laser operating on all lines at 500 mW and containing a few milliwatts of the fundamental ν= 1→0 band component, is focused into an absorption cell containing a mixture of CO and Ar. The absorption of this infrared radiation is monitored by the optoacoustic effect. A second CO laser operating cw and capable of providing 8 W on all lines but not lasing on the ν= 1→0 band component, is then focused into the same volume in the absorption cell. With both lasers simultaneously focused into the absorption cell, strong fluorescence from the irradiated region is detected by a photomultiplier tube. Modulation of the signal intensity with time is observed, and indicates chemical destruction of the CO in the cell. An analysis and kinetic modelling calculation of this experiment shows that it is possible to excite CO up to high vibrational quantum numbers (ν40) at gas temperatures up to 800 K. by means of CO laser irradiation at the fundamental ν= 1→0 band component. One source responsible for the fluorescence signal observed in the experiment is identified as the 4th positive A 1Π→X 1Σ+ spontaneous emission. Although the present kinetic model does not incorporate the chemical processes that may lead to the production of additional fluorescing species such as C2, good agreement is obtained with the observed fluorescence signal characteristics. 相似文献
25.
Nabil Dawahre Gang Shen Soner Balci William Baughman David S. Wilbert Nick Harris Lee Butler Rich Martens Seongsin Margaret Kim Patrick Kung 《Journal of Electronic Materials》2012,41(5):801-808
Wide-bandgap zinc oxide (ZnO) semiconductors and nanowires have become important materials for electronic and photonic device
applications. In this work, we report the growth of well-aligned single-crystal ZnO nanowire arrays on sapphire substrates
by chemical vapor deposition and the development of atom probe tomography, an emerging nanoscale characterization method capable
of providing deeper insight into the three-dimensional distribution of atoms and impurities within its structure. Using a
metal-catalyst-free approach, the influence of the growth parameters on the orientation and density of the nanowires were
studied. The resulting ZnO nanowires were determined to be single crystalline, with diameter on the order of 50 nm to 150 nm
and length that could be controlled between 0.5 μm to 20 μm. Their density was on the order of high 108 cm−2 to low 109 cm−2. In addition to routine characterizations using scanning and transmission electron microscopy, x-ray diffraction, photoluminescence,
and Raman spectroscopy, we developed the atom probe tomography technique for ZnO nanowires, comparing the voltage pulse and
laser pulse modes. In-depth analysis of the data was carried out to determine the accurate chemical composition of the nanowires
and reveal the incorporation of nitrogen impurities. The current–voltage characteristics of individual nanowires were measured
to determine their electrical properties. 相似文献
26.
27.
D. I. Naiduss W. W. Kiesewetter S. L. Dikanskaja J. Schapiro R. Meurice J. Cartiaux E. F. Posorski G. N. Murthy S. Mihaéloff A. D. Rich J. J. Vollertsen Gh. Ghimicescu G. Kotsis C. T. Townsend J. A. Esty F. C. Baselt R. Dubrisay J. Gascon E. R. Scheggia K. M. Renner E. S. Miller C. A. Mitchell A. G. Sossin und S. E. Spektor 《Fresenius' Journal of Analytical Chemistry》1939,118(1-2):48-51
Ohne Zusammenfassung 相似文献
28.
R. U. Khafizov N. Severijns O. Zimmer H. -F. Wirth D. Rich S. V. Tolokonnikov V. A. Solovei M. R. Kolhidashvili 《JETP Letters》2006,83(1):5-9
The aim of this work is the experimental observation of and research into a rare neutron mode, the radiative beta decay, where
a new particle, the radiative gamma quantum, is formed along with the expected decay products: a beta electron, a recoil proton,
and an antineutrino. The discovery of this rare neutron decay mode was conducted through identification of triple-coincidence
events: simultaneous registration of a beta electron, a proton, and a radiative gamma quantum. The ordinary neutron decay
was registered by double coincidences of a beta electron and a recoil proton. The statistics collected allow one to deduce
the branching ratio (BR) BR = (3.2 ± 1.6) × 10−3 (90% C.L.) in the gamma energy region greater than 35 keV. This value of BR is consistent with standard electroweak theory.
The text was submitted by the authors in English.
An erratum to this article is available at . 相似文献
29.
Rich Brossart 《电子产品世界》2007,(9):115-115,123
当前和可预见的未来,便携式装置的设计者们都面临着一个可怕的挑战--全球的消费者在对尺寸更小、价格更低、功能特色更为丰富而且电池寿命更长的便携式装置的追求上总是贪得无厌.像真人电视秀一样,同一种产品上的设计迭代次数将呈指数式增长. 相似文献
30.
Substitution effects on the stereochemical outcome of bisspiroketalization on the C1-C17 carbon backbone of azaspiracid is presented. A possible explanation is offered to explain the observed stereochemical outcome. 相似文献