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101.
This paper considers the possibility of using tris--diketonate complexes of europium in polymethylmettacrylate as luminescent UV radiation converters for widening the range of spectral sensitivity of photodetectors (including TV ones). The absolute quantum yields of luminescence have been determined. Converters for the 220–380-nm range providing a quantum efficiency of the silicon photodiode and the CCD matrix in the UV range up to 40% of the efficiency at the maximum of the spectral characteristic have been devised. 相似文献
102.
The special cubic system (a natural and simPlest generaIization of thequadratic system of C1ass (l) to cubic system)f.'x = yl y = --x 6y a,x' a2xy a,y' a#x' a,x'y a.xy' a,y' (1)was first studied by the Russian Mathematician I.S.KukIes [ll on the Ilecessaryand sufficient conditions fot O(0,0) to be a ccnter of (1). After [ll, the sameproblem and also the order of O as a fine fOcus were also studied iIl [2--l0] and[13-19], so (l) is now called as a "Kukles system". In l988-… 相似文献
103.
Cooper对质心定向运动速度的空间分布规律及“邻近效应” 总被引:3,自引:0,他引:3
在零场下 ,由超导电流密度的两种表达形式 ,导出了超导载流子质心定向运动速度的空间分布规律 ,并由毕萨定律定性地解释了“邻近效应” 相似文献
104.
105.
Synthesis and characterization of Ca2Sn1-xCexO4 with blue luminescence originating from Ce^4+ charge transfer transition 下载免费PDF全文
Ce^4+-doped Ca2SnO4 with a one-dimensional structure, which emits bright blue light, is prepared by using a solid-state reaction method. The x-ray diffraction results show that the Ce^4+ ions doped in Ca2SnO4 occupy the Sn^4+ sites. The excitation and emission spectra of Ca2Sn1-xCexO4 appear to have broad bands with peaks at - 268nm and -442nm, respectively. A long excited-state lifetime (-83μs) for the emission from Ca2Sn1-xCexO4 suggests that the luminescence originates from a ligand-to-metal Ce^4+ charge transfer (CT). The luminescent properties of Ca2Snl_xCexO4 have been compared with those of Sr2CeO4, which is the only material reported so far to show Ce^4+ CT luminescence. More interestingly, it is observed that the emission intensity of Ca2Sn1-xCexO4 with a small doping concentration (x - 0.03) is comparable to that of Sr2CeO4 in which the concentration of active centre is 100%. 相似文献
106.
A. A. Leito R. B. Capaz N. V. Vugman C. E. Bielschowsky 《Journal of Molecular Structure》2002,580(1-3):65-73
Detailed embedded-cluster quantum-chemistry (ROHF, UHF and UMP2) calculations of hyperfine interactions for the F center in KCl, NaCl and LiCl are presented. Our values for the isotropic hyperfine interaction show a good general agreement with experiments. We show that a careful treatment of the lattice environment, local lattice distortion, spin polarization and correlation are important for this good agreement. 相似文献
107.
Pier Luigi Papini 《TOP》2005,13(2):315-320
Many problems in continuous location theory, reduce to finding a best location, in the sense that a facility must be located
at a point minimizing the sum of distances to the points of a given finite set (median) or the largest distances to all points
(center). The setting is often assumed to be a Banach space.
To have a better understanding concerning the structure of location problems, it may occur also in rather simple cases.
In this paper we indicate two simple examples of four-point sets such that one of the two problems indicated has a solution,
while the other one has no solution. Also, we list papers containing examples previously given, dealing with this lack of
optimal solutions. 相似文献
108.
109.
A.G. Andreev M. Georgiev M.S. Mladenova V. Krastev 《International journal of quantum chemistry》2002,89(4):371-376
Off‐center impurity ions in solids often perform rotations around their regular lattice sites. Unlike quasifree rotors with rotational line spectra subject to textbook attention in quantum mechanics, the off‐center species are hindered rotors with spectra quantized in rotational bands. These bands occur because of tunneling through barriers arising along the orbital path. For an off‐center ion rotating along a planar orbit, such as the Li+ impurity nearest‐neighboring an F center in alkali halide, the hindered rotation will give rise to specific magnetic moments that couple to and quantize external magnetic fields normal to the orbital plane. We present a simple theory and estimates of Li+ magnetic dipoles and rotational bands to find conditions for an experimental verification. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 相似文献
110.
Jing Sun Jian‐Gong Cheng Wen‐Qing Zhu Shi‐Jie Ren Hong‐Liang Zhong Dan‐Li Zeng Jun‐Ping Du Er‐Jian Xu Ying‐Chun Liu Qiang Fang 《Journal of polymer science. Part A, Polymer chemistry》2008,46(16):5616-5625
A new X‐shaped π‐conjugated monomer comprising of fluorene units and anthracene units was synthesized, and it was used to fabricate the new X‐shaped π‐conjugated polymers and investigate the properties of the new polymers. Using different molar ratios between such monomer and a fluorene monomer gave three polymers that showed higher absolute PL quantum yields than the linear polyfluorene (PF) in the solid state. After thermal annealing at 200 °C for 4 h, the linear PF showed an additional bathochromic emission at about 550 nm, whereas such red‐shifted emission was fully eliminated for the X‐shaped polymers. The electroluminescent devices based on the X‐shaped polymers with a configuration of ITO/PEDOT:PSS/polymer/LiF/Ca/Al displayed blue emission with low turn‐on voltage and high brightness. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5616–5625, 2008 相似文献