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61.
Chowdhury Budhadeb Mondal Monohar Hossain Barman Milan Krishna Saha Bidyut 《Research on Chemical Intermediates》2019,45(2):789-800
Research on Chemical Intermediates - In the present study the copper(III)-periodate (DPC) has been synthesized in an alkaline medium. The stability of this complex is significantly dependent on the... 相似文献
62.
S. Barman C. Rajesh G. P. Das C. Majumder 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):613-625
Here we report a systematic theoretical study of the structure and
electronic properties of Snn-1Pb and Pbn-1Sn (n = 2-13) clusters
and compare these results with pure Snn and Pbn to understand the
influence of the dopant elements. The calculations were carried out using
the density functional theory with generalized gradient approximation for
the exchange-correlation potential. Extensive search based on large number
of initial configurations has been carried out to locate the stable isomers
of Snn-1Pb and Pbn-1Sn (n = 2-13) clusters. The relative
stability of Snn-1Pb and Pbn-1Sn (n = 2-13) clusters is analyzed
based on the calculated binding energies and second difference in energy.
The stability analysis of these clusters suggests that, while the
substitution of Sn by Pb lowers the stability of Snn clusters, presence
of Sn enhances the stability of the Pbn clusters. The results suggest
that while for Snn-1Pb, n=4, 7, 10, 12 clusters are more stable than
their respective neighbors, Pbn-1Sn clusters with n = 4, 7 and 9 are
found to be more stable. Based on the fragmentation pattern it is seen that
for Snn-1Pb and Pbn-1Sn clusters favor monomer evaporation of the
Pb atom up to n =11 and n =12, respectively. Unlike this trend, the
Sn11Pb undergoes fission type fragment into Sn5Pb and Sn6
clusters. A comparison between our theoretical results and surface induced
dissociation experiment shows good agreement, which gives confidence on the
prediction of the ground state geometries. 相似文献
63.
64.
65.
Thermal rate coefficients for the removal (reaction + quenching) of O2(1sigma(g)+) by collision with several atmospheric molecules were determined to be as follows: O3, k3(210-370 K) = (3.63 +/- 0.86) x 10(-11) exp((-115 +/- 66)/T); H2O, k4(250-370 K) = (4.52 +/- 2.14) x 10(-12) exp((89 +/- 210)/T); N2, k5(210-370 K) = (2.03 +/- 0.30) x 10(-15) exp((37 +/- 40)/T); CO2, k6(298 K) = (3.39 +/- 0.36) x 10(-13); CH4, k7(298 K) = (1.08 +/- 0.11) x 10(-13); CO, k8(298 K) = (3.74 +/- 0.87) x 10(-15); all units in cm3 molecule(-1) s(-1). O2(1sigma(g)+) was produced by directly exciting ground-state O2(3sigma(g)-) with a 762 nm pulsed dye laser. The reaction of O2(1sigma(g)+) with O3 was used to produce O(3P), and temporal profiles of O(3P) were measured using VUV atomic resonance fluorescence in the presence of the reactant to determine the rate coefficients for removal of O2(1sigma(g)+). Our results are compared with previous values, where available, and the overall trend in the O2(1sigma(g)+) removal rate coefficients and the atmospheric implications of these rate coefficients are discussed. Additionally, an upper limit for the branching ratio of O2(1sigma(g)+) + CO to give O(3P) + CO2 was determined to be < or = 0.2% and this reaction channel is shown to be of negligible importance in the atmosphere. 相似文献
66.
67.
Papadimitriou VC Talukdar RK Portmann RW Ravishankara AR Burkholder JB 《Physical chemistry chemical physics : PCCP》2008,10(6):808-820
Rate coefficients over the temperature range 206-380 K are reported for the gas-phase reaction of OH radicals with 2,3,3,3-tetrafluoropropene (CF(3)CF=CH(2)), k(1)(T), and 1,2,3,3,3-pentafluoropropene ((Z)-CF(3)CF=CHF), k(2)(T), which are major components in proposed substitutes for HFC-134a (CF(3)CFH(2)) in mobile air-conditioning units. Rate coefficients were measured under pseudo-first-order conditions in OH using pulsed-laser photolysis to produce OH and laser-induced fluorescence to detect it. Rate coefficients were found to be independent of pressure between 25 and 600 Torr (He, N(2)). For CF(3)CF=CH(2), the rate coefficients, within the measurement uncertainty, are given by the Arrhenius expression k(1)(T)=(1.26+/-0.11) x 10(-12) exp[(-35+/-10)/T] cm(3) molecule(-1) s(-1) where k(1)(296 K)=(1.12+/-0.09) x 10(-12) cm(3) molecule(-1) s(-1). For (Z)-CF(3)CF=CHF, the rate coefficients are given by the non-Arrhenius expression k(2)(T)=(1.6+/-0.2) x 10(-18)T(2) exp[(655+/-50)/T] cm(3) molecule(-1) s(-1) where k(2)(296 K)=(1.29+/-0.06) x 10(-12) cm(3) molecule(-1) s(-1). Over the temperature range most relevant to the atmosphere, 200-300 K, the Arrhenius expression k(2)(T)=(7.30+/-0.7) x 10(-13) exp[(165+/-20)/T] cm(3) molecule(-1) s(-1) reproduces the measured rate coefficients very well and can be used in atmospheric model calculations. The quoted uncertainties in the rate coefficients are 2sigma (95% confidence interval) and include estimated systematic errors. The global warming potentials for CF(3)CF=CH(2) and (Z)-CF(3)CF=CHF were calculated to be <4.4 and <3.6, respectively, for the 100 year time horizon using infrared absorption cross sections measured in this work, and atmospheric lifetimes of 12 and 10 days that are based solely on OH reactive loss. 相似文献
68.
69.
Nikita Barman Saikat Banerjee Paula Brandão Antonio Bauzá 《Journal of Coordination Chemistry》2016,69(7):1188-1205
Four complexes based on N,N′-bis(2-pyridylmethylene)-1,3-propanediamine (L) and different Cd(II) salts have been synthesized and characterized by single-crystal X-ray diffraction analysis. The complexes are [Cd2(L)2(μ-Cl)2](ClO4)2 (1), [Cd2(L)2(μ-Br)2](ClO4)2 (2), [Cd(L)I](ClO4) (3), and [Cd(L)(NCS)2] (4). L exhibits the same coordination mode in 1–4. The radius of each anion plays a role in affecting the structures and luminescent intensities of the final products. CdCl2, CdBr2, and CdI2 react with L to produce chloride or bromido-bridged binuclear complexes and mononuclear iodido complex, respectively, whereas an unusual mononuclear trigonal prismatic (TP) 4 is obtained when thiocyanate was used as a coligand. Photoluminescence properties of all the complexes show that the trend of fluorescence intensity is 1 > 4 > 2 > 3. All four complexes exhibit different supramolecular interactions such as C–H/σ, π–π, and C–H/π and hydrogen bonding interactions. The experimental findings are complemented by density functional theory (DFT) calculations. 相似文献
70.
Birinchi K. Das Rama K. Barman 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1025-1026
The title compound, [Cu2(C2H3O2)4(C6H4N2)2], has the familiar lantern‐type structure that is characteristic of dimetal tetracarboxylates of copper and several other transition elements. The molecule lies about an inversion centre and the Cu atom is present in a distorted square‐pyramidal coordination environment, consisting of four O atoms in equatorial positions and the pyridyl‐N atoms of the two 4‐cyanopyridine ligands in axial positions. 相似文献