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排序方式: 共有150条查询结果,搜索用时 931 毫秒
41.
42.
1INTRODUCTIONThecompoundwithcompositionIRE,O,:ZSiO,(RE~rareEarth)exhibitsex-tensivepolymorphismthatarecharacterizedbyboundariesateuropiumandholmiumalongtheseriesoftrivalentrareearths.Asfarasthestructureisconcerned,typeCisofspecialstabilitybecauseitsrangecanbeextendedbeyondthesmallestrareearthLug toScs tl'z}.Notlongago,wereportedstructureofNd,Si,O,withstructureformAt33.SynthesisandstructureofErZSiZO7withstructureformCarehereinre-ported.2EXPERIMENTAL'ThestartingmaterialsEr,O,… 相似文献
43.
Reflection Asymmetric Relativistic Mean Field Approach and Its Application to the Octupole Deformed Nucleus ^226Ra 下载免费PDF全文
A reflection asymmetric relativistic mean field (RAS-RMF) approach is developed by expanding the equations of motion for both the nucleons and the mesons on the eigenfunctions of the two-centre harmonic-oscillator potential. The efficiency and reliability of the RAS-RMF approach are demonstrated in its application to the well-known octupole deformed nucleus 226Ra and the available data, including the binding energy and the deformation parameters, are well reproduced. 相似文献
44.
Marsella MJ Reid RJ Estassi S Wang LS 《Journal of the American Chemical Society》2002,124(42):12507-12510
Tetra(2,3-thienylene) is a thiophene-fused [8]annulene capable of undergoing redox-induced dimensional changes. The feasibility of efficiently translating this intrinsic function into a single polymeric electromechanical actuator is investigated by both experiment and density functional theory (B3LYP 6-31G[d,p]). A study of tetra(2,3-thienylene) and its homodimer reveal that redox-induced conformational change is conserved upon dimerization, a result that implicates similar behavior in the corresponding polymer. Theoretical predictions yield a maximum redox-induced dimensional change of 5.92% per repeat unit for the homodimer. Cyclic voltammetry reveals complete reversibility for the corresponding redox cycle. The latter two facts establish tetra(2,3-thienylene) as a suitable building block for single-molecule electromechanical actuators. 相似文献
45.
Na+, K+, Mg2+∥Cl-, SO2-4-H2O五元体系35 ℃介稳相图研究 总被引:3,自引:0,他引:3
研究得出(Na+, K+, Mg2+∥Cl-, SO2-4-H2O)五元体系35 ℃时的介稳溶解度数据,绘制了该体系35 ℃的介稳相图,共有9个为氯化钠所饱和的结晶区域:氯化钾、钾芒硝(3K2SO4*Na2SO4)、钾镁矾(K2SO4*MgSO4*4H2O)、钾盐镁矾(KCl*MgSO4*2.75H2O)、光卤石(KCl*MgCl2*6H2O)、白钠镁矾(Na2SO4*MgSO4*4H2O)、硫酸钠、六水硫酸镁(MgSO4*6H2O)和水氯镁石(MgCl2*6H2O). 所得35 ℃介稳相图与Vant Hoff 25 ℃稳定相图比较有较大区别:软钾镁矾(K2SO4*MgSO4*6H2O)、七水硫酸镁、五水硫酸镁及四水硫酸镁结晶区域消失,钾镁矾和钾盐镁矾结晶区域显著扩大. 所得35 ℃介稳相图与25 ℃介稳相图区别很大:软钾镁矾和七水硫酸镁结晶区域消失,同时出现了钾镁矾和钾盐镁矾的结晶区域. 在该五元体系35 ℃介稳相平衡研究中发现析出的是钾盐镁矾的低水化合物(KCl*MgSO4*2.75H2O). 相似文献
46.
47.
二烯丙基三硫化物键合硅胶的制备、表征及抗菌作用 总被引:2,自引:0,他引:2
采用固液相表面连续反应法,制备含硫的偶联剂γ-巯基丙基键合硅胶(MPS),通过引发剂,使偶联剂键合硅胶表面的巯基与二烯丙基三硫化物发生巯烯加成反应制备二烯丙基三硫化物键合硅胶(DTS)。采用元素分析、红外光谱、热重分析和质谱分析测试技术进行结构表征,MPS和DTS的键合量分别为1.73和0.27 mmol/g。通过抑菌环试验考察了DTS对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、产气杆菌和变形杆菌的抑菌活性,抑菌环分别为9.0、8.1、10.1、9.2和8.9 mm。实验同时采用搅拌涂布平板法考察了牛肉膏蛋白胨基中DTS含量对金黄色葡萄球菌和大肠杆菌抑菌效果的影响。结果表明,DTS对5种细菌均有良好的抑制活性。消除了蒜素固有的浓烈的大蒜气味,同时保存了二烯丙基三硫化物的抗菌活性。初步探讨了该DTS的抗菌机理。 相似文献
48.
A density functional theory (DFT) is used to investigate
molecular orientation of hard rod fluids in a hard slit. The DFT
approach combines a modified fundamental measure theory (MFMT)
for excluded-volume effect with the first order thermodynamics
perturbation theory for chain connectivity. In the DFT approach,
the intra-molecular bonding orientation function is introduced.
We consider the effects of molecular length (i.e. aspect ratio
of rod) and packing fraction on the orientations of hard rod
fluids and flexible chains. For the flexible chains, the chain
length has no significant effect while the packing fraction
shows slight effect on the molecular orientation distribution.
In contrast, for the hard rod fluids, the chain length
determines the molecular orientation distribution, while the
packing fraction has no significant effect on the molecular
orientation distribution. By making a comparison between
molecular orientations of the flexible chain and the hard rod
fluid, we find that the molecular stiffness distinctly affects
the molecular orientation. In addition, partitioning coefficient
indicates that the longer rodlike molecule is more difficult to
enter the confined phase, especially at low bulk packing
fractions. 相似文献
49.
通过正相和反相硅胶柱层析,从四齿四棱草根部的乙醇提取物中分离纯化出4个环肽化合物,经波谱分析等鉴定了其结构,其中2个新化合物的结构分别为cyclo(-N-Pro1-Pro2-Phe1-Phe2-Leu1-Ser-Thr-Leu2-CO)(1,四棱草肽C)和cyclo(-N-Pro1-Pro2-His-Gly-Val-Asn-Ile-Trp-CO)(2,四棱草肽D). 相似文献
50.