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排序方式: 共有177条查询结果,搜索用时 15 毫秒
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用稀土(镱)杂多酸盐/多壁碳纳米管修饰的玻碳电极测定亚硝酸根 总被引:2,自引:0,他引:2
将多壁碳纳米管分散在镱(Ⅲ)杂多酸盐溶液中,将上述获得的悬浊液滴涂在玻碳电极表面,制备了镱(Ⅲ)杂多酸盐/多壁碳纳米管修饰的玻碳电极(YbHS-MWCNT′s/GCE)。采用交流阻抗法对电极表面的性能进行了表征,采用循环伏安法对其电化学性能进行研究。研究发现,亚硝酸根在该修饰电极上出现一个氧化峰,氧化峰电位在-0.45V处,提出了用循环伏安法测定亚硝酸根的方法。亚硝酸根的浓度在5.0×10-6~1.0×10-4mol.L-1范围内,氧化峰电流与其浓度呈线性关系。修饰电极用于环境水样中亚硝酸根离子的测定,回收率在97.2%~98.0%之间。 相似文献
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《Journal of magnetism and magnetic materials》2001,223(1):33-38
An effect of local atomic disorder on the electronic structure and magnetic moments in Fe2TiSn is studied. The band structure is calculated by the spin-polarised tight-binding linearised muffin tin orbital (TB LMTO). We found that the Fe2TiSn alloy in which Fe occupy two FCC sublattices in L21-type structure is paramagnetic. The substitution of Fe atoms onto titanium or tin positions leads to an increase of the magnetic moment. 相似文献
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This paper investigates theoretically the electronic structure and
transport of a two-level quantum dot irradiated under a strong laser
field at low temperatures. Using the method of Keldysh equation of
motion for nonequilibrium Green functions, it examines the
time-averaged density of states and conductance for the system with
photon polarization parallel with and perpendicular to the tunnelling
current direction respectively. It is demonstrated that, by analysing
some numerical examples, more photon sidebands resonance states and
multi- and single-photon transitions are found when diagonal matrix
elements dominate the interaction, while the electronic transitions
due to multiphoton absorption are more or less suppressed when
off-diagonal interaction dominates. 相似文献
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Ying?Chen Bo?Wu Yu?Feng Hong-Kuan?Yuan Hong?ChenEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(1):24
Using the first-principles calculations based on density functional theory, we investigate the more d-electrons doping effects on the electronic structure and magnetism of the parent inverse Heusler alloy Ti2CoAl by the substitution of Nb and V atoms for Ti(A) and Ti(B) atoms locating at the two inequivalent sublattices. The Ti2CoAl is half-metallic with Fermi level near the top of the minority-spin valence band and hence its spin-polarization is easily reduced by the spin-flip excitation. Our total energy calculations show that the V/Nb doping at the Ti(A)/Ti(B) site is energetically favorable compared with the Ti(B)/T(A) site due to the lower total energy. Our band structure calculations indicate that for the V doped compounds, half-metallicity can be well retained regardless of doping sites and percentages except for the case of Ti(A)-site doping with x = 1, while for Nb doped compounds, the half-metallicity persists only in Ti(B)-site doping with different percentages. For the doped compounds with half-metallicity, the Fermi level shifts from the top of minority-spin valence band to the bottom of minority-spin conduction band with increasing content of x, and typically, the doped compounds (V in Ti(A) and Ti(B) sites at x = 0.75 and 0.5, respectively; Nb in Ti(B) site at x = 0.5), whose Fermi levels are adjusted to the expected positions to effectively inhibit the spin-flip excitation are promising candidates for spintronics applications. 相似文献
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本文K2S2O8作氧化剂,以MnSO4为锰源,于120℃不同水热反应时间下制备得到不同形貌的纳米MnO2,用X射线衍射(XRD)和扫描电镜(SEM)对样品的结构与形貌进行表征。采用循环伏安法、交流阻抗和恒流充放电技术对纳米MnO2赝电容性能进行测试。结果表明,随着反应时间的增加,纳米MnO2形貌由海胆结构转变为纳米线,水热处理12 h时纳米MnO2比电容为282 F.g-1,水热处理时间延长至24 h时比电容下降为161 F.g-1,继续反应至36 h比电容又上升为203 F.g-1。 相似文献
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约束粒子群算法求解自融资投资组合模型研究 总被引:1,自引:0,他引:1
在马克维茨投资组合的均值-方差模型框架下,给出限制投资数量的自融资投资组合优化模型.在金融市场上有广泛应用,为了有效地求解此类问题的最优解,采用一种基于广义学习策略的约束粒子群算法(CPSO).CPSO算法具有广义的学习策略,极大地提升了种群的多样性,进而提升种群跳出局部最优解的能力.在基准函数测试中,结果显示CPSO算法有较好的运行结果.在自融资投资组合优化模型上,优化结果表明CPSO算法是可行的,有效的,并有较好的优化结果. 相似文献