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161.
采用傅里叶变换红外光谱仪(FT-IR)、N2吸脱附、X射线衍射(XRD)、透射电子显微镜(TEM)揭示了微波辅助-KOH处理对活性炭的物理化学性能的影响规律。 结果表明,活性炭表面的含氧基团的种类增加,微孔明显减少,中大孔的比例增大。 通过浸渍-原位还原方法制备了Pt、Pd、Ru、Rh负载微波辅助-KOH处理活性炭催化剂,并对其催化p-叔丁基-α-甲基肉桂醛选择性加氢性能进行了研究。 发现Pt具有优异的C=O加氢选择性,而Pd具有优良的C=C加氢选择性。 进一步研究了Pd-Pt双组分催化剂催化p-叔丁基-α-甲基肉桂醛加氢产物分布,随着Pt含量的增加, C=O选择性逐步提高, C=C选择性逐渐下降,且当m(Pd)∶m(Pt)=4∶1时,其催化剂的催化性能最佳。 相似文献
162.
Runwu Peng Yunxia Ye Zhixiang Tang Chujun Zhao Dianyuan Fan 《Optics Communications》2006,265(1):106-110
The propagation expression of a broadband laser passing through a dispersive wedge is derived on the basis of the Huygens-Fresnel diffraction integral. Smoothing effects caused by the phase perturbation of the dispersive wedge on the intensity profiles are investigated in detail. The phase perturbation of the dispersive wedge induces a relative transverse position shift between the diffraction patterns of different frequency components. The relative transverse position shift is of great benefit to the fill of the intensity peaks of some patterns in the valleys of others when these patterns are overlapped and thus the smoothing effect is achieved. 相似文献
163.
Ran Li Xiufeng Song Hong He Xiaodong Yu Bingbing He Zhixiang Shi 《Journal of Physics and Chemistry of Solids》2011,72(4):233-494
Tb-doped SrSi2O2N2 phosphors with promising luminescent properties were synthesized by the conventional solid-state reaction method, characterized by powder X-ray diffraction and studied by photoluminescence excitation and emission spectra. The synthesized materials exhibited a weak blue emission and a strong green emission in the region of 400-470 nm and 480-650 nm, which are attributed to 5D3→7Fj (j=5, 4, 3) and 5D4→7Fj (j=6, 5, 4, 3) transitions of Tb3+, respectively. The green emission from 5D4→7F5 at 543 nm showed the highest intensity under the optimized concentration of 0.1 mol, after which the quenching concentration became relevant. The quenching behavior of the emission of Tb3+ was explained by the cross-relaxation of its excited state. 相似文献
164.
Laser sintering of gold-microparticle ink was examined in this study. Laser-sintered gold conductive patterns were characterized by using scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), cross-cut tape test and destructive bond wire pull tests. The effects of laser power on microstructure and adhesion of gold conductive patterns were investigated. It was found that the microstructure of gold conductive patterns became denser with increase of laser power. The gold conductive patterns treated with laser power of 2 W showed poor adhesiveness of 2B in accordance with ASTM D3359-08. The adhesion level of gold conductive patterns increased to 5B by elevating laser power to 8 W. The adhesion mechanism of gold conductive patterns on silicon substrate was discussed and wire bonding test was also performed on gold conductive patterns. Wire breakage took place at the practical pull strength of around 5 gf. 相似文献
165.
Chen Shi Bingye Dai Min Liu Zhixiang Xu 《Journal of Macromolecular Science: Physics》2014,53(4):662-672
A novel molecularly imprinted polymer/magnetic chitosan microsphere (MIP/MCM) was prepared by a surface molecular imprinting technique in combination with a sol–gel process, using estriol as the template, γ-aminopropyltrimethoxysilane as the functional monomer, tetraethoxysilicane as the cross-linker, and magnetic chitosan as the support material. The adsorption ability and selectivity of the polymeric material toward estriol were evaluated. The results indicated that the prepared material had higher adsorption capacity and selectivity toward estriol than the non-imprinted polymer/MCM. The theoretical maximum adsorption capacity (Q max) was 8.13 mg g?1, and the equilibrium dissociation constant (K d) was 625.0 mg mL?1. The functionalized material had fast uptake kinetics, 83.64% of the saturated adsorption capacity was obtained within a period of 60 min, and the adsorption almost reached equilibrium within 90 min. This prepared material has potential to be used as a sorbent in solid-phase extraction (SPE) to enrich trace estriol in samples. 相似文献
166.
167.
Using finite time thermodynamic theory, an irreversible steady-flow Lenoir cycle model is established, and expressions of power output and thermal efficiency for the model are derived. Through numerical calculations, with the different fixed total heat conductances () of two heat exchangers, the maximum powers (), the maximum thermal efficiencies (), and the corresponding optimal heat conductance distribution ratios () and () are obtained. The effects of the internal irreversibility are analyzed. The results show that, when the heat conductances of the hot- and cold-side heat exchangers are constants, the corresponding power output and thermal efficiency are constant values. When the heat source temperature ratio () and the effectivenesses of the heat exchangers increase, the corresponding power output and thermal efficiency increase. When the heat conductance distributions are the optimal values, the characteristic relationships of and are parabolic-like ones. When is given, with the increase in , the , , , and increase. When is given, with the increase in , and increase, while and decrease. 相似文献
168.
Quasi-interpolation of radial basis functions on finite grids is a very useful strategy in approximation theory and its applications. A notable strongpoint of the strategy is to obtain directly the approximants without the need to solve any linear system of equations. For radial basis functions with Gaussian kernel, there have been more studies on the interpolation and quasi-interpolation on infinite grids. This paper investigates the approximation by quasi-interpolation operators with Gaussian kernel on the compact interval. The approximation errors for two classes of function with compact support sets are estimated. Furthermore, the approximation errors of derivatives of the approximants to the corresponding derivatives of the approximated functions are estimated. Finally, the numerical experiments are presented to confirm the accuracy of the approximations. 相似文献
169.
Dr. Lingjun He Dr. Junling Meng Prof. Jing Feng Dr. Fen Yao Dr. Lifang Zhang Dr. Zhixiang Zhang Prof. Xiaojuan Liu Prof. Hongjie Zhang 《Chemphyschem》2020,21(1):51-58
Rare-earth (RE) doped zinc oxides (ZnO) are regarded as promising materials for application in versatile color-tuned devices. However, the understanding of underlying luminescence mechanism and the rule of 4 f-related electronic transition is still limited, which is full of significance for the exploration of advanced RE-based ZnO phosphors. Thus, a series of ZnO : RE (RE=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb) phosphors have been investigated by means of first-principles calculations. Meanwhile, we also consider the effect of native defects (VO, VZn) on the luminescence of ZnO : RE phosphors. Accordingly, four types of electric-dipole allowed transition processes are figured out in ZnO : RE family. Additionally, we manifest that the VO can further improve the luminescent performance of ZnO : RE phosphors, and give insightful guidance to design desired RE-based ZnO materials with excellent luminescence. 相似文献
170.
提出了一种能够同时检测具有紫外吸收(UV)的有机物和无紫外吸收的无机物含量的强阴离子交换色谱法(IEC)。以检测己内酰胺副产物中的1-磺酸基环己烷羧酸(SCCA)粗盐为具体实例开展研究。强阴离子色谱柱以及UV检测器被用于同时分析SCCA和硫酸根离子。本实验基于高效液相色谱-间接光度检测法(HPLC-IPD)原理来测定SCCA和硫酸根离子,选用具有强紫外吸收能力的邻苯二甲酸作为本底试剂加入到流动相中产生信号。硫酸根离子和SCCA分别在0.10~10.0 g/L和0.50~40.0 g/L范围内呈良好的线性关系,相关系数分别为0.99914和0.99997;加标回收率分别为98.50%~101.00%和93.33%~97.40%,定量限均为0.10 g/L,符合色谱检测要求。该方法具有良好的分离选择性,可用于SCCA和硫酸根离子的同时检测。 相似文献