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1.
Single bacterial cells, each expressing a different library variant, were compartmentalized in aqueous droplets of water-in-oil (w/o) emulsions, thus maintaining a linkage between a plasmid-borne gene, the encoded enzyme variant, and the fluorescent product this enzyme may generate. Conversion into a double, water-in-oil-in-water (w/o/w) emulsion enabled the sorting of these compartments by FACS, as well as the isolation of living bacteria cells and their enzyme-coding genes. We demonstrate the directed evolution of new enzyme variants by screening >10(7) serum paraoxonase (PON1) mutants, to yield 100-fold improvements in thiolactonase activity. In vitro compartmentalization (IVC) of single cells, each carrying >10(4) enzyme molecules, in a volume of <10 femtoliter (fl), enabled detection and selection despite the fast, spontaneous hydrolysis of the substrate, the very low initial thiolactonase activity of PON1, and the use of difusable fluorescent products. 相似文献
2.
Gaseous HZnCl has been synthesized for the first time in a high-temperature tube furnace with a dc discharge in a flowing mixture of pure HCl and Zn vapor. The vibration-rotation emission spectrum of HZnCl was recorded at high resolution using a Fourier transform spectrometer. The H-Zn stretching modes (nu(1)) of the H(64)Zn(35)Cl, H(66)Zn(35)Cl, H(68)Zn(35)Cl, and H(64)Zn(37)Cl species, as well as the 2nu(1)-nu(1) hot band of the most abundant isotopologue H(64)Zn(35)Cl, were observed near 1966 cm(-1). A least-squares fit was performed for each of the four observed isotopologues, and their spectroscopic constants were determined. 相似文献
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Curtis P. Rinsland Linda Chiou Chris Boone Peter Bernath Emmanuel Mahieu 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(18):2127-2134
The first measurement of the HCFC-142b (CH3CClF2) trend near the tropopause has been derived from volume mixing ratio (VMR) measurements at northern and southern hemisphere mid-latitudes for the 2004–2008 time period from spaceborne solar occultation observations recorded at 0.02 cm−1 resolution with the ACE (atmospheric chemistry experiment) Fourier transform spectrometer. The HCFC-142b molecule is currently the third most abundant HCFC (hydrochlorofluorocarbon) in the atmosphere and ACE measurements over this time span show a continuous rise in its volume mixing ratio. Monthly average measurements at northern and southern hemisphere mid-latitudes have similar increase rates that are consistent with surface trend measurements for a similar time span. A mean northern hemisphere profile for the time span shows a near constant VMR at 8–20 km altitude range, consistent on average for the same time span with in situ results. The nearly constant vertical VMR profile also agrees with model predictions of a long lifetime in the lower atmosphere. 相似文献
5.
Randall H. Skelton Chris D. Boone Peter F. Bernath Bernard Pinchemel 《Journal of Molecular Spectroscopy》2003,219(1):1-12
The A′1Π-X1Σ+ near infrared system of strontium oxide (SrO) was observed at high spectral resolution by measuring the chemiluminescence from a Broida flow reactor using a Fourier transform spectrometer. In total, 32 bands from , , were measured within the spectral region at a resolution of . Vibrational levels of the upper state were observed up to vA′=4, and more than 5600 rotational lines were assigned. Incorporating previously published high resolution data for the A1Σ+-X1Σ+ system, a global fit to both data sets yields improved Dunham constants for the ground state and for the lower vibrational levels (vA′=0, 1, and 2) of the A′1Π state. Because perturbations arising from interactions with the b3Σ+ and A1Σ+ states affect the higher vibrational levels of the A′1Π state more strongly, levels vA′=3 and 4 were represented by effective band constants in the fits. RKR potentials for the X1Σ+,A′1Π, and b3Σ+ states have been generated utilizing all the available data, Franck-Condon factors have been calculated for the A′1Π-X1Σ+ system, and A′1Π∼b3Σ+ and A′1Π∼A1Σ+ perturbations are discussed. 相似文献
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The laser-induced fluorescence (LIF) spectrum of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) system of Br(2) was recorded by Fourier transform spectroscopy (FTS). The LIF spectra were obtained by using continuous-wave dye laser excitation in the spectral region 16 800-18 000 cm(-1). About 1800 rotationally resolved lines were recorded in 96 fluorescence progressions, originating from the 10 = v' = 22 vibrational levels of the B(3)Pi(0(+))(u) state and involving the 2 = v" = 29 levels of the X(1)Sigma(+)(g) ground state of the three isotopomers of bromine, (79)Br(2), (81)Br(2), and (79,81)Br(2). These data, together with (79)Br(2) data from a previous FTS absorption study [S. Gerstenkorn, P. Luc, A. Raynal, and J. Sinzelle, J. Phys. (France) 48, 1685-1696 (1987)], were analyzed to yield improved Dunham constants for the ground state. A Rydberg-Klein-Rees (RKR) potential energy curve was computed for the X(1)Sigma(+)(g) state (v" = 0-29). The equilibrium bond length was found to be R(e)(X(1)Sigma(+)(g)) = 2.2810213(20) ?. Copyright 2000 Academic Press. 相似文献
8.
Jeremy J. Harrison Peter F. Bernath 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(14):2347-2354
The proposed satellite mission ACCURATE consists of a small constellation of satellites in low Earth orbit, combining microwave occultation for thermodynamic state profiling with infrared-laser occultation for greenhouse gas and line-of-sight wind profiling. The mission aims to detect six greenhouse gas molecules with four additional isotopologues (H2O, CO2, CH4, N2O, O3, CO, 13CO2, OC18O, HDO, and H218O) in the upper troposphere and lower stratosphere in the 4000-5000 cm−1 spectral region. Greenhouse gas profiles will be retrieved to within 1-2% accuracy using a ‘differential’ method, requiring two spectral points for each species - one to sample the spectral line and the other nearby to sample the baseline.An estimation of retrieval errors for the ACCURATE mission reveals that errors in spectroscopic line parameters dominate all other error sources. Poor knowledge of the spectroscopy introduces systematic errors into the retrieved greenhouse gas profiles. Using a simple approach, it was shown that the best line parameters currently available are too large to allow retrievals of greenhouse gases to within the stated ACCURATE mission goals of 1% accuracy for CO2 and 2% for all other species. Therefore, spectroscopic line parameters for targeted lines need to be improved before the ACCURATE mission can be launched. Requirements have been formulated in this direction, and laboratory experiments outlined that could meet these requirements. 相似文献
9.
Andrew Janca P.F. Bernath N.F. Zobov S.V. Shirin Oleg L. Polyansky Jonathan Tennyson 《Journal of Molecular Spectroscopy》2003,219(1):132-135
Fourier transform emission spectra were recorded using a mixture of H2O and D2O at a temperature of 1500 °C. The spectra were recorded in three overlapping sections and cover the wavenumber range 1800-3932 cm−1. This spectrum is analyzed together with a previously reported one spanning the 380-2190 cm−1 range [Parekunnel et al., J. Mol. Spectrosc. 2001 (28) 101]. This analysis leads to 4409 newly assigned HDO emission lines. This work particularly extends data on the (200) and (120) states of HDO for which newly determined energy levels are presented. 相似文献
10.
George SA Silfvast WT Takenoshita K Bernath RT Koay CS Shimkaveg G Richardson MC 《Optics letters》2007,32(8):997-999
Detailed spectroscopic studies on extreme UV emission from laser plasmas using tin and lithium planar solid targets were completed. At 13.5 nm, the best conversion efficiency (CE) for lithium was found to be 2.2% at intensities near 7 x 10(10) W/cm(2). The highest CE measured for tin was near 5.0% at an intensity close to 1 x 10(11) W/cm(2). 相似文献