全文获取类型
收费全文 | 457篇 |
免费 | 130篇 |
国内免费 | 61篇 |
专业分类
化学 | 205篇 |
晶体学 | 12篇 |
力学 | 9篇 |
综合类 | 7篇 |
数学 | 14篇 |
物理学 | 401篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 10篇 |
2020年 | 33篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 22篇 |
2016年 | 21篇 |
2015年 | 15篇 |
2014年 | 31篇 |
2013年 | 46篇 |
2012年 | 25篇 |
2011年 | 20篇 |
2010年 | 32篇 |
2009年 | 26篇 |
2008年 | 23篇 |
2007年 | 31篇 |
2006年 | 27篇 |
2005年 | 21篇 |
2004年 | 29篇 |
2003年 | 18篇 |
2002年 | 23篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 22篇 |
1998年 | 24篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有648条查询结果,搜索用时 31 毫秒
61.
A. V. Naumov Yu. V. Meteleva N. L. Sermakasheva V. N. Semenov G. F. Novikov 《Journal of Applied Spectroscopy》2002,69(1):120-125
We have investigated the luminescence and microwave photoconductivity of cadmium sulfide and zinc sulfide films obtained from halide (Cl, Br, I) thiocarbamide coordination compounds. We show that the formation of the impurity and intrinsic centers of radiative recombination is governed not only by preparative conditions, but also by the chemical nature of the initial thiocarbamide coordination compounds. 相似文献
62.
63.
电子与离子碰撞过程中辐射复合截面的相对论理论研究 总被引:5,自引:5,他引:0
在相对论理论框架下,研究了自由电子与离子碰撞的辐射复合过程.在分析影响单电子体系(类H+离子及碱金属离子)辐射复合截面主要因素的基础上,总结出了辐射复合截面在不同情况下的变化规律. 相似文献
64.
Kong Hong Jin Lee Jae Yong Shin Yun Sup Byun Jae Oh Park Hee Su Kim Hyogun 《Optical Review》1997,4(2):277-283
Beam recombination characteristics were numerically investigated in array laser amplification using stimulated Brillouin scattering phase conjugation. To clarify the effect of piston errors due to imperfect phase locking, spatial intensity profiles of the beam recombination output were calculated in both the near and the far field on the basis of Rayleigh-Sommerfeld diffraction theory. The analyses indicate that piston errors are seriously detrimental to the quality of a beam recombination output and should be eliminated by a proper phase locking. It is also found that the gap between the beam splitting-combining wedges has a negligible effect.Presented at 1996 International Workshop on Interferometry (IWI ‘96), August 27-29, Saitama, Japan. 相似文献
65.
过电离等离子体复合升温和绝热膨胀 总被引:2,自引:2,他引:0
给出了类H—C离3d5/2-2p3/2跃迁复合机制产生X光激光的电子密度-电子温度增益目标区域,研究了电离转复合处等离子体特征、复合阶段电子密度变化规律及影响电子温度的两个主要因素:作功冷却与复合升温,并给出了这两个因素的近似表达式. 相似文献
66.
Summary The luminescence of barium fluoride excited by X-rays has been recordedvs. wavelength. The spectrum shows two components due to recombination of excitons bound to Frenkel defects and to luminescent
centres also active in the thermoluminescent process. The results are interpreted by means of a model based on the Prener
and Williams recombination scheme. 相似文献
67.
F. A. Ptashchenko 《Journal of Applied Spectroscopy》1998,65(3):469-472
The kinetics of the decay in the electroluminescence intensity after gating a rectangular pulse of current in the p-n-transition
with inhomogeneities, in particular, accumulations of dislocations is calculated. The basic assumptions are: on gating the
rectangular pulse of current, a portion of the electrons injected into the thin p-region is extracted into the n-region, whereas
the same number of electrons are injected into the inhomogeneity where they recombine without emission; the intensity of nonradiative
recombination on the inhomogeneity is limited by drift of majority charge carriers (by leakages). It is shown that nonradiative
recombination on inhomogeneities leads to nonexponential kinetics of electroluminescence, whose instantaneous relaxation time
decreases with time.
Odessa State Naval Academy, 8 Didrikhson St., Odessa, 270029, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 3, pp. 450–453, May–June, 1998 相似文献
68.
Suresh Chandra 《Pramana》1980,14(1):41-46
The effect of dielectronic recombination as an excitation process in the intensity of solar x-ray lines of calcium ions is
investigated. It is found that x-ray line intensities are enhanced by 15% to 88% with the inclusion of dielectronic recombination
as an excitation mechanism. 相似文献
69.
The low thermal stability of hydrogenated amorphous silicon (a‐Si:H) thin films limits their widespread use for surface passivation of c‐Si wafers on the rear side of solar cells. We show that the thermal stability of a‐Si:H surface passivation is increased significantly by a hydrogen rich a‐Si:H bulk, which acts as a hydrogen reservoir for the a‐Si:H/c‐Si interface. Based on this mechanism, an excellent lifetime of 5.1 ms (at injection level of 1015 cm–3) is achieved after annealing at 450 °C for 10 min. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
70.
With the help of electrochemical, steady state and time resolved fluorescence (fluorescence lifetimes by using time correlated single photon counting technique) and nanosecond laser flash photolysis methods, the nature of charge separation along with the energy wasting charge recombination processes within a short-chained organic dyad 1-(4-Bromo-phenyl)-3-(2-methoxy-naphthalen-1-yl)-propenone (MNBA) has been revealed. In MNBA, the donor 2-methoxynaphthalene (2MNT) is connected with the acceptor p-bromoacetophenone (PBA) by an unsaturated olefinic bond. Though in the ground state elongated type structure (E-form) is observable from NMR spectra but on photoexcitation, another conformers possibly of the nature of folded type isomeric species (termed as Z-isomer) were also apparent from time resolved fluorescence measurements. However, preponderance of elongated form in the excited singlet state has been established from this time resolved measurements. NMR study on photoirradiated sample and theoretical predictions from computations using CIS method with Lanl2DZ basis set also indicate in favor of the propositions made on the formations of the two possible conformers and the stability of elongated isomeric species in the electronic excited state from the experimental results. The energy wasting charge recombination rate, kCR, determined from the transient absorption measurements by nanosecond laser flash photolysis (LFP) technique was found to be (kCR, ∼1.9×105 s−1) significantly lower than the charge-separation rate, kcs∼9.4×107 s−1, measured from the time resolved fluorescence. This observation demonstrates that MNBA may serve as an efficient candidate to construct artificial light energy conversion devices or components of molecular photovoltaic cells. 相似文献