全文获取类型
收费全文 | 304篇 |
免费 | 18篇 |
国内免费 | 4篇 |
专业分类
化学 | 248篇 |
晶体学 | 2篇 |
力学 | 10篇 |
数学 | 29篇 |
物理学 | 37篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 19篇 |
2020年 | 19篇 |
2019年 | 21篇 |
2018年 | 24篇 |
2017年 | 18篇 |
2016年 | 27篇 |
2015年 | 15篇 |
2014年 | 21篇 |
2013年 | 30篇 |
2012年 | 29篇 |
2011年 | 27篇 |
2010年 | 15篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2000年 | 4篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
排序方式: 共有326条查询结果,搜索用时 15 毫秒
81.
Research on Chemical Intermediates - TiO2 nanotubes and Ag/TiO2 nanotubes (TNT) have been synthesized by simple hydrothermal and solvothermal method and were characterized by XRD, UV, ICP, TEM,... 相似文献
82.
Optimization of parameters in preparation of PCM microcapsules based on melamine formaldehyde through dispersion polymerization 总被引:1,自引:0,他引:1
Fahimeh Khakzad Zeinab Alinejad Abbas Rezaee Shirin-Abadi Maryam Ghasemi Ali Reza Mahdavian 《Colloid and polymer science》2014,292(2):355-368
Microencapsulated phase change materials have attracted special attention due to their wide applications in saving and releasing energy. Here, microencapsulation of hexadecane (HD) in melamine formaldehyde shell was carried out through in situ dispersion polymerization in the aqueous media. Some important parameters such as stabilizer type and amount, surfactant amount, homogenization conditions as the critical affective factors on final particle size, morphology, and thermal resistance of the microcapsules were investigated extensively. The obtained microcapsules were concurrently analyzed by SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques. SEM images showed that the best stabilization was achieved by polyvinyl alcohol. Also, particle size, as an indication of surface area for heat transfer properties, showed a decrement by increasing stabilizer amount, surfactant amount, and homogenization speed. The amount of entrapped HD and efficiencies of microencapsulation were determined by DSC, and the reason for observing such changes were discussed in detail. Thermal stability of the microcapsules as an important property for their performance was investigated, too. The results illustrated that an improved thermal stability would be obtained by an efficient stabilization in the emulsification step. Also the highest thermal stability up to 388 °C was reached at homogenization speed of 6,000 rpm. Finally, the optimized conditions for desirable encapsulation were proposed in such systems. 相似文献
83.
Bayat Zeinab Saeedzadeh Elham Vahidfar Nasim Sadeghi Mahdi Farzenefar Saeed Daha Fariba Johari Salehi Yalda 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):691-700
Journal of Radioanalytical and Nuclear Chemistry - Radiocolloides are essential for the detection of metastatic lymph nodes in breast cancer. In this study [67Ga]Ga-phytate, as an long-lived... 相似文献
84.
The electrochemical oxidation of the three fluoroquinolone drugs FQs: gatifloxacin GTF, moxifloxacin MXF and sparfloxacin SPF, at the bare and DNA‐modified glassy carbon electrodes has been studied by voltammetric techniques. The three FQs showed one irreversible oxidation peak at potential range 0.85–0.91 V vs. Ag‐AgCl, in phosphate buffer of pH 7.0. Differential pulse voltammetry (DPV) and UV‐absorption spectroscopic techniques were employed to probe the interaction between the FQs and calf thymus double stranded deoxyribonucleic acid (ds CT‐DNA). From electrochemical data, the binding constant between DNA and the gatifloxacin, moxifloxacin and sparfloxacin are calculated to be 3228, 2596 and 2857 M?1 respectively. Based on electrochemical and spectroscopic results, the mode of binding of fluoroquinolone to DNA through combined effect of intercalation and electrostatic interaction was concluded. A detection scheme based on a preconcentration and differential pulse voltammetric (DPV) determination at dsDNA modified glassy carbon electrode (DNA/GCE) was proposed for the trace determination of the studied analytes. The developed method was successfully applied to the determination of the FQs in pharmaceutical formulations. 相似文献
85.
In this study, an organic conjugated molecule, 4,4′-[ethane-1,2-diylidenedi(nitrilo)] dibenzenthiol designed and is proposed
as a molecular wire. Structural and electronic responses of this aromatic molecular wire to the static electric field with
intensities −1.6 × 10−2 to +1.6 × 10−2 a.u., are studied using the DFT-B3LYP/6-31G* level of theory. Natural bond orbital atomic charge analysis shows that the
imposition of static external electric field induces polarization—localization of charge on the two ends of molecule, especially
on considered terminal contact sulfur atoms. The frontier molecular orbitals (MOs) energy levels including the highest occupied
MO (HOMO) and the lowest unoccupied MO (LUMO) and the HOMO–LUMO gap (HLG) values are modified by the static electric field
as well. The electric dipole moment and polarizability of the proposed molecular wire under the studied electric field strengths
are considerably increased. The current–voltage characteristic curve is estimated for the proposed molecular wire. 相似文献
86.
It is well known that the primary Bjerknes force is the origin of the trapping of sonoluminescing bubble in the sound field in liquid. In the present Letter, the quantitative investigation of the behavior of hydrodynamic force on the moving sonoluminescing (SL) bubble introduces the new role of stabilizing the trajectory motion of the bubble for primary Bjerknes force. Using a complete force balanced radial-translational dynamics, it is analytically discussed that by increasing the bubble distance from the antinode of the sound field the increase of the magnitude of inward Bjerknes force, controls the size of the domain of the bubble trajectory. At this time the wake produced by the rapid variation of the bubble's relative translational velocity to the surrounding liquid, changes the bubble direction of motion through the effect of history force. The required momentum for accelerating the SL bubble around the central antinode is produced by the added mass force at the bubble collapse. It is revealed in a re-examination of the coupled radial-translational dynamics for a trapping bubble that because of the bubble lower translational acceleration caused due to the lower added mass force and the bubble attraction towards the acoustic antinodes in presence of inward Bjerknes force, the small bubble will be trapped at the antinode of the sound field. 相似文献
87.
We have constructed a collaboration network for physicists based in Iran working in different disciplines. By discussing properties like collaborators per author, shortest path, betweenness, and the concept of power in networks for this local model, and comparing with the global model, we understand how a developing country in the Middle East is contributing to the scientific growth in the world statistically. In this comparison, we found some properties of the local model which were not in accordance with the standard global society of science, which should be considered in developing the future policies. Our results show significant differences in factors like the degree and the diameter of the networks. Even though the diversity of disciplines is low in contrast with the rest of the world according to the diameter of networks, people are reluctant to collaborate as their degree shows. 相似文献
88.
89.
90.
Rahmani Niloufar Abbasi-Radmoghaddam Zeinab Riahi Siavash Mohammadi-Khanaposhtanai Mohammad 《Structural chemistry》2020,31(6):2129-2145
Structural Chemistry - Structural analysis of topoisomerase IIα catalytic inhibitors exhibited anti-tumor properties to use them in cancer therapeutic procedures. In this study, a quantitative... 相似文献