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31.
Triterpenoid Saponins from Luculia pincia Hook 总被引:1,自引:0,他引:1
Two new triterpenoid saponins, cincholic acid-3-O-β-D-xylopyranoside, 28-O-β-D-glucopyranosyl ester (I), quinovic acid28-O-β-D-glucopyranosyl ester (4), and a new phenolic glucoside, 4-[4‘‘-O-( 2‘‘, 3‘‘, 5‘‘, 6‘‘-tetrahydroxy phenyl)-β-D-glucoside]-l-butene (2), along with five known triterpenoid saponins and one phenolic glucoside were isolated from the n-butanol fraction of the stems of Luculia pinciana Hook. Their structures were established by means of spectroscopic methods. 相似文献
32.
Quasi-elastic Neutron Scattering combined with Molecular Dynamics simulations have been carried out to gain further insight
into the CO2 dynamics in LiY and NaY Faujasites. In both materials, it was pointed out that the transport diffusivity (DT) increases with the loading whereas the self diffusivity (DS) decreases. In addition, it was shown that LiY exhibits a significant slower CO2 self diffusivity process due to a strong interaction between the Li+ cation and the adsorbate molecules at the initial stage of diffusion. This result is consistent with higher simulated activation
energy in this cation exchanged faujasite form. By contrast, the transport diffusivity is revealed to be slightly faster in
LiY than in NaY. 相似文献
33.
<正>Two new oleanane-type saponins,crotalarioside A(1) and crotalarioside B(2),were isolated from the roots of Polygala crotalarioides.Their structures were elucidated on the basis of spectroscopic and chemical evidence. 相似文献
34.
不同树脂对瓜果腐霉代谢产物中除草活性成分的吸附分析 总被引:1,自引:0,他引:1
利用HPD400、HPD500、HPD600、HPD700、HPD850、ADS-17、D101、DM130大孔吸附树脂对瓜果腐霉培养滤液中除草活性成分的吸附情况进行了研究,通过对树脂吸附后的流出液和洗脱液的浓缩物进行HPLC检测分析,确定了其除草活性成分。实验发现,在所选择的8种树脂中以HPD500、HPD850、HPD600、ADS-17对除草活性成分的吸附能力最强,其中以HPD500和HPD600树脂的10%的乙醇洗脱液中除草活性成分含量最高。综合结果表明,以HPD500树脂作为吸附瓜果腐霉培养滤液中除草活性成分的适宜树脂。研究发现,HPD500树脂对除草活性成分吸附和解吸附的最佳条件是:吸附最适温度为20℃,树脂吸附饱和度为33.75mL/g,较适宜吸附流速为2BV/h,较适宜脱附流速为1BV/h,洗脱剂浓度为10%乙醇,洗脱剂用量为2.5BV。 相似文献
35.
The functional Ito formula, in the form df() = f( + d ) f(),is formulated and proved in the context of a Lie algebra L associatedwith a quantum (non-commutative) stochastic calculus. Here fis an element of the universal enveloping algebra U of L, andf() + d() f() is given a meaning using the coproductstructure of U even though the individual terms of this expressionhave no meaning. The Ito formula is equivalent to a chaoticexpansion formula for f() which is found explicitly. 1991 MathematicsSubject Classification: primary 81S25; secondary 60H05; tertiary18B25. 相似文献
36.
Ab initio calculations with complete geometry optimisation have been used to study internal rotation in compounds of the type XCH = CHSH, X = CN, H, CH3 and F, with X located trans to the sulphur atom. Potential functions for the CS torsion have been obtained for each case and it has been established that the dominant framework changes accompanying internal rotation in these molecules involve the CCS angle and CS bond length. Furthermore, it has been shown that the nature of the substituent X significantly affects the molecular conformation of the SH group. The observed trends are discussed in terms of a simple model. 相似文献
37.
Internal rotation in the compounds XCH=CHOH, X= CN, H and F, with the group X located trans to the oxygen atom has been studied using ab initio computational techniques with complete geometry optimisation. The relaxation of the molecular framework accompanying the torsional vibration is described and the significant changes in the internal rotation function around the C---O bond which arise upon changing the group X discussed.
The structure of the syn rotamer of ethenol itself, calculated with a variety of basis sets, is compared with the experimental geometry. 相似文献
38.
Christopher Plant James E. Boggs John N. Macdonald Gwilym A. Williams 《Structural chemistry》1992,3(1):3-8
In this report the effects of basis set size and electron correlation on the internal rotation barrier heights in ethene thiol are investigated and compared with experimental data. At all levels of theory reasonable agreement is obtained for the barrier tosyn/anti rotation (experimental value: 9.6 kJ/mol), however, theanti barrier (experimental value: 0.14 kJ/mol) is consistently overestimated by approximately a factor of 10. A comparison of ab initio predictions of torsional energy distributions and rotational constant variations as a function of torsional state with the corresponding experimental quantities is presented. 相似文献
39.
G. Maurin D. Plant S. Devautour-Vinot A. Nicolas F. Henn J. C. Giuntini 《The European physical journal. Special topics》2007,141(1):113-116
Molecular Dynamics simulations have been carried out to
address the question of cation migration upon adsorption of methanol in NaY
Faujasite system as a function of the loading. It has been shown that at low
and intermediate loadings, SII cations can migrate toward the center of the
supercage due strong interaction with the adsorbates, followed by hopping of
SI' cations from the sodalite cage into the supercage to fill vacant SII
sites. SI cations mainly remain trapped in their initial sites whatever the
loading. At higher loading, only limited motion is observed for SII cations
due to steric effects induced by the adsorbates within the supercage. These
simulated results are in good agreement with those extracted by Complex
Impedance Spectroscopy measurements, which provided the evolution of the
number of extraframework cations in the different crystallographic sites as
a function of the treatment temperature. 相似文献
40.