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The time-resolved total emission of SO2 (B1B1→X1A1) at 354.9 nm were monitored following the direct excitation by a 266 nm laser pulse. A three-level model was proposed to deal with SO2 (X1A1, A1A2, B1B1) system. From a kinetic treatment of these measurements, the coupling coefficient, ξ, and the relaxation time, τ, relating to the high vibronic levels of A1A2 and B1B1 states were first obtained. It is found that ξ and τ values keep basically constant, reflecting the characteristics of the studied system. In addition, the quenching rate constants of SO2 (A1A2, B1B1) by some alkane and chloromethane molecules were measured at room temperature. The formation cross sections of complexes of SO2 (A1A2, B1B1) and quenchers were calculated by means of a collision complex model. It is shown that the dependence of the formation cross section of complex on the number of C(SINGLEBOND)H or C(SINGLEBOND)Cl bonds is generally in agreement with that of the measured quenching cross section. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 831–837, 1998 相似文献
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采用RRKM理论和疏松过渡态模型计算了N(4S)+CH2X(X=F,Cl)反应的微正则速率常数和通道分支比.计算结果表明,在较低的内能下(E=280.29 kJ/mol), N(4S)+CH2F的主要产物为NCHF+H,占总产物的59.2%,次要产物为H2CN+F,占37.4%.而N(4S)+CH2Cl反应在E=267.78 kJ/mol时,主要产物是H2CN+Cl,占90.3%, NCHCl+H只占9.0%.在内能较高的时候(取E=500.00 kJ/mol), N(4S)+CH2F的主要通道并未变化,而N(4S)+CH2Cl的主要通道变为NCHCl+H,比例为51.5%, H2CN+Cl的比例降到40.4%. 相似文献
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利用Ar/CF4、Ar/CF2Cl2或Ar/CF3COOH混合气体的直流脉冲放电产生CF自由基,观测了260~360nm范围内转动分辨的CF自由基双光子共振增强多光子电离谱。分析表明,该段光 谱对应于CF自由基3pπD2Πr(ν'=2~6,r=3/2,1/2)←←X2Πr(ν"=0,r=3/2,1/2)的共振激发。对观测的振动带进行了转动分析,并获得了3p里德堡态的转动常数和自旋-轨道分裂值。 相似文献
16.
Zhenyu Sheng Qinhua Song Fan Gao Xiaoguo Zhou Jiang Li Jinghua Dai Haihong Sun Quanxin Li Shuqin Yu Xingxiao Ma 《Research on Chemical Intermediates》2000,26(7-8):715-725
The pH effects on the photochemical reaction of amino acids and related dipeptides with 4-nitroquinoline 1-oxide (4NQO) as a photosensitizer have been investigated by laser flash photolysis. The obtained kinetic parameters show that the electron transfer from Tryptophan (Trp), Tyrosine (Tyr) as well as dipeptides containing Trp and/or Tyr residue to triplet 4NQO (T4NQO) are efficient, but inefficient from methionine (Met) and dipeptides containing neither Trp nor Tyr. The result was supported by the calculated values of the free energy change from measured oxidation potentials for the electron transfer. It was demonstrated that Trp and Tyr residues are initial reaction sites with T4NQO, while Tyr/O? radical may be final species for Trp-Tyr dipeptide. In acidic aqueous solutions, the self-quenching rate constants of T4NQO and the rate constants of electron transfer from amino acids to T4NQO decrease with decreasing pH. In alkaline solutions, amino acids are easily oxidized by 4NQO under irradiation of laser pulse, and no transient absorption signal was observed. 相似文献
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用一束波长为210.27 nm的激光将CS2分子激发至预离解态1 B2(1 Σ+u),用另一束激光通过激光诱导荧光(LIF)方法检测碎片CS,在250.5~286.5 nm获得了CS碎片A1 Π←X1 Σ+振转分辨的激发谱.通过对光谱强度的分析,获得了CS碎片v″=0~8的振动布居和v″=1,4~8振动态的转动布居.结果发现,碎片CS的振动布居呈双模结构,分别对应于CS2分子1 B2(1 Σ+u)态的两个解离通道,即CS(X1 Σ+,v″=0~9)+S(3PJ)和CS(X1 Σ+, v″=0~1)+S(1 B2).由此得到两个解离通道的分支比S(3PJ): S(1 B2)为5.6±1.2.与前人193 nm处的研究结果相比, 210.27 nm激发更有利于S(3PJ)通道的生成.此外,实验还发现CS的转动布居不满足热平衡分布,为两个Boltzmann分布的合成. 相似文献
18.
For all minimal immersions of the 2-sphereS
2 into the unit 2m-sphereS
2m
with area 2π[m(m+1)+2], we are able to give an explicit representation by some real parameters. This representation is rather important in the
study of minimal 2-spheres inS
2m
because the parameters concerned are independent of each other. Particular examples are given and a classification theorem
is also obtained.
Supported by NNSF of China and NSF of Henan 相似文献
19.
研究了CS2 分子1B2 (1Σ+u )预离解态线形势垒下的g振动能级光解动力学,包括预解离寿命、产物振转布居、平动振动转动能量分配和解离通道分支比.在实验过程中,一束可调谐激光激发超声射流冷却的CS2 分子到1B2 (1Σ+u )电子态,光解产物CS用另一束可调谐激光通过激光诱导荧光(LIF)方法检测.通过拟合光解碎片激发谱的谱峰轮廓,获得了源于不同跃迁初始态的1B2 (1Σ+u )态g振动能级的预解离寿命.通过分析CS的LIF光谱,则获得了不同光解波长下CS碎片的v=0~8振动态布居、v=1、4 ~8振动态的转动布居、能量分配以及两个预解离通道CS(X1Σ+ ) +S(3PJ)和CS(X1Σ+ ) +S(1D2 )的分支比.实验还考察了初始态弯曲振动量子数v2″、振动角动量量子数l对解离动力学的影响.发现v2″的影响不大,而l的影响却是明显的.较大的l(=K)对应于较短的寿命和较小的通道分支比S(3PJ) /S(1D2 ),即大的l(=K)有利于预解离的发生,同时更有利于产生S(1D2 ). 相似文献
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