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排序方式: 共有72条查询结果,搜索用时 15 毫秒
1.
Silyl stabilized azanes: reactions of lithiumbis(trimethylsilyl)hydrazine with trialkyltin halides 总被引:1,自引:0,他引:1
Lithium 1,2-bis(trimethylsilyl)hydrazine (1a) reacts with Me3SnCl, Et3SnBr and Bu3SnCl to form bis(trimethylsilyl)(trimethylstannyl)hydrazine (2a), (triethylstannyl)bis(trimethyl silyl)hydrazine (2b) and (tributylstannyl)bis(trimethylsilyl)hydrazine (2c), respectively. Compounds 2a and 2b undergo disproportionation at room temperature to form bis(trimethylsilyl)bis(trimethylstannyl)hydrazine (3a) and bis(triethylstannyl)bis(trimethylsilyl)hydrazine (3b). In contrast, 2c is highly stable and can withstand such a reaction up to 150 °C. The monostannylated products, 2a, 2b and 2c do not get lithiated at NH and instead undergo transmetallation in their reaction with RLi or Li to form lithiumbis(trimethylsilyl)hydrazine (1a). 相似文献
2.
Godbole MD Roubeau O Clérac R Kooijman H Spek AL Bouwman E 《Chemical communications (Cambridge, England)》2005,(29):3715-3717
The novel octanuclear cluster [Mn8O2(OH)2(OMe)12(OAc)2(Mesalim)4] (1) presents SMM behaviour with a relatively high experimental energy barrier (eff/kB= 36.0 K) as shown by its dc and ac magnetic properties. 相似文献
3.
Anita Topkar S. Praveenkumar Bharti Aggarwal S. K. Kataria M. D. Ghodgaonkar 《Pramana》2007,69(6):1085-1088
A specific research and development program has been carried out by BARC in India to develop the technology for large area
silicon strip detectors for application in nuclear and high energy physics experiments. These strip detectors will be used
as pre-shower detector in the CMS experiment at LHC, CERN for π
0/λ rejection. The fabrication technology to produce silicon strip detectors with very good uniformity over a large area of ∼40
cm2, low leakage currents of the order of 10 nA/cm2 per strip and high breakdown voltage of >500 V has been developed by BARC. The production of detectors is already under way
to deliver 1000 detector modules for the CMS and 90% production is completed. In this paper, research and development work
carried out to develop the detector fabrication technology is briefly described. The performance of the silicon strip detectors
produced in India is presented. The present status of the detector technology is discussed.
相似文献
4.
M.J. Singh S.K. Goel R. Shanker D.O. Kataria N. Madhavan P. Sugathan J.J. Das D.K. Avasthi A.K. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):7-13
Measurements were carried out to deduce the transverse kinetic energies of highly charged argon recoil ions produced in single
collisions of 120 MeV ions with argon atoms in which the post collision charge states of the projectiles were not determined. A time of flight
spectrometer was designed and fabricated to detect the charge states of recoils. Experimental procedures for optimizing the
spectrometer for extraction, transmission and detection of recoils are described. A simple approach for determining the transverse
kinetic energy of the recoil ions from FWHM of the peaks is reported. This method is shown to be independent of the choice
of collision partners and requires only the knowledge of the physical values of “optimized parameters” of time-of-flight spectrometer
used in the experiment. The transverse kinetic energy of the recoil ions determined from the present approach is found to
vary from 0.03 eV for to 4.02 eV for Ar10+. These values are compared with the results reported by earlier workers and are shown to follow a q2-behaviour up to a charge state q
=8+ of the recoil ions.
Received: 5 February 1998 / Revised: 8 June 1998 / Accepted: 11 June 1998 相似文献
5.
Intermediate mass fragments emitted in the reaction Ag+14N at 100, 160 and 250 MeV bombarding energy
L.G. Moretto S.K. Kataria R.C. Jared R. Schmitt S.G. Thompson 《Nuclear Physics A》1975,255(2):491-508
The fragments produced in the reaction between a 14N beam of various energies and a natural Ag target have been studied. The atomic numbers of the fragments have been identified up to Z = 17 by means of a E-ΔE counter telescope. The cross sections, the kinetic energy distributions as well as the angular distributions have been measured for each atomic number. The kinetic energy distributions show two components: a high-energy component (quasi-elastic), prevailing at angles close to the grazing angles and for atomic numbers close to Z = 7, and a low-energy component (relaxed), at energies close to the Coulomb repulsion energy, present at all angles and for all the Z. A detailed study of the relaxed components of the kinetic energy seems to account for both them means and the widths of these distributions on a purely statistical basis. The cross sections of the relaxed components appear to be quite large at low Z and to decrease rapidly to a fairly constant value in the region of 10 ≦ Z ≦ 17. A marked even-odd alternation in the cross sections is observed. The angular distributions are strongly forward peaked for Z < 7. For Z > 7 the forward peaking decreases rapidly until, for Z > 13, the limiting form 1/sinθ is attained. Evidence for the existence of a diffusion process along the mass asymmetry coordinate is discussed. 相似文献
6.
The leptodermous expansion of the total ground state energy of a nucleus into volume, surface, curvature and gauss curvature
contributions has been studied starting from a semi-classical energy density formalism of extended Thomas Fermi type. A numerical
procedure was used to obtain the surface energy and curvature energy contributions from surface moments of energy density
profilesH(r) for a sequence of nuclei withN=Z and neglecting the coulomb interaction for the three Skyrme forces. A transition to the liquid drop model type expansion
in increasing powers ofA
−1/3 is then made, taking into account the dependence of the central density and the surface structure on the mass of the nucleus.
It is found that there is no inconsistency between the curvature contribution to the total energy in the leptodermous expansion
and theA
−1/3 term contribution in the liquid drop model expansion. It has been shown that the earlier apparent anomaly between the above
two methods arises due to the use of semi-infinite approximation and the mass dependence of the central density and the surface
structure of finite nuclei. 相似文献
7.
J. Niemeyer N. D. Kataria M. R. Dietrich C. Politis H. Koch R. Schöllhorn H. Eickenbusch 《Zeitschrift für Physik B Condensed Matter》1987,69(1):1-9
The ac-Josephson effect could be demonstrated up to dc voltages of 20 mV on the I–V characteristic of adjustable YBa2Cu3O7/YBa2Cu3O7 point contacts at 4.2 K. A detailed analysis of the rf power dependence of the size of microwave-induced constant voltage steps is given for microwave frequencies of 70 and 90 GHz. The results prove that electron pairing is responsible for the superconductivity in YBa2Cu3O7. 相似文献
8.
Walczak W Pipalia NH Soni M Faruqi AF Ralph H Maxfield FR Webb BL 《Combinatorial chemistry & high throughput screening》2006,9(9):711-718
The conversion of the genomic information produced by the recent sequencing projects into a comprehensive understanding of the human proteome has yet to occur. A new technology that represents a potential bridge between genomics and proteomics is reverse transfection. Reverse transfection cell microarrays are produced by overlaying cDNA arrays with mammalian cells, generating localized clusters of transfected cells with each cluster overexpressing a unique protein. This miniaturized cell-based microarray format affords parallel functional analysis of thousands of cDNA constructs in a high throughput format. In this report we document the development of a co-transfection methodology for reverse transfection applications. The demonstrated high co-transfection efficiency with a "marker" plasmid encoding for GFP enables the identification of transfected cells and eliminates the need for epitope-tagged constructs in cell-based high throughput screening applications using reverse transfection. This co-transfection method was used to study in parallel the structure/function of multiple versions of the v-Src protein using automated fluorescence microscopy. The wild-type v-Src protein and four mutants having insertions or deletions in the SH2 or SH3 domains displayed high levels of tyrosine kinase activity in HEK293T cells. Three other mutated v-Src proteins, including a kinase-dead version, were shown to be defective for tyrosine kinase activity. This reverse co-transfection approach is applicable for high throughput screening of both cDNA libraries and positional scanning recombinant protein libraries. 相似文献
9.
S. Kataria Satyaprakash Sahoo S.A. Barve S. Dash D.S. Patil A.K. Tyagi A.K. Arora 《Solid State Communications》2009,149(43-44):1881-1883
Diamond-like carbon films are deposited on silicon substrates at different substrate bias using ECR-CVD technique. Raman spectroscopic studies show the presence of broad G and D peaks. In contrast to the position of D peak, the G peak shows a systematic red-shift with increase in the bias voltage. From the analysis it is found that an increase in bias voltage decreases the sp2 cluster diameter. Furthermore, two additional Raman peaks at around 690 and 880 cm?1 are also observed. These peaks, forbidden in the first order Raman scattering, arise due to the breakdown of phonon selection rule in graphitic nanoclusters. 相似文献
10.
SnCl4 acts primarily as an oxidant and oxidizes monolithium bis(trimethylsilyl) hydrazide 1 to mainly bis(trimethylsilyl)amine, BSA and tris(trimethylsilyl)hydrazine, TrSH and itself get reduced to SnCl2. Similarly, reaction of SnCl4 with dilithiumbis(trimethylsilyl) hydrazide 2, oxidizes it to lithium tris(trimethylsilyl)hydrazide, Li-TrSH. Reaction of dichlorostannane (reduction of oxidation state of tin from +4 to +2) with 1 gives a simple substitution reaction and give a pale yellow solid, 1,4-bis(trimethylsilyl)-1,2,4,5-tetraza-3,6-distannacyclohexane, 3b. Whereas, in reaction of 2 with SnCl2 intermediate stannimine [(Me3Si)2N-NSn], tetramerizes and further loses tetrakis(trimethylsilyl)tetrazene, TST to give a cubane compound [(Me3Si)N-Sn]4, 4. 相似文献