全文获取类型
收费全文 | 65篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 59篇 |
力学 | 1篇 |
综合类 | 1篇 |
数学 | 4篇 |
物理学 | 7篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 1篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2003年 | 2篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有72条查询结果,搜索用时 15 毫秒
61.
本文给出了HL-1托卡马克在通常欧姆放电和偏压诱发H模放电条件下,脉冲注入杂质气体的实验结果以及对杂质在通常欧姆等离子体和偏压诱发H模等离子体中的输运研究结果。实验结果表明,在HL-1上偏压诱发H模等离子体中对杂质的约束性能明显优于在通常欧姆等离子体中对杂质的约束性能。杂质输运的数值模拟结果说明,无论在通常欧姆等离子体中,还是在偏压诱发H模等离子体中,杂质的输运系数都比新经典理论预计的要大得多,输运是反常的。在偏压诱发的H模等离子体中引入杂质输运“位阱”概念,能够对杂质离子约束时间长的实验现象进行很好的描述。合理地解释了在偏压杂质注入实验中杂质辐射上升时间长、衰减慢的现象。 相似文献
62.
63.
Xingya Wang Binyu Zhao Wangguo Ma Ying Wang Prof. Xingyu Gao Prof. Renzhong Tai Prof. Xingfei Zhou Prof. Lijuan Zhang 《Chemphyschem》2015,16(5):1003-1007
The dependence of the morphology of interfacial nanobubbles on atomically flat substrates with different wettability ranges was investigated by using PeakForce quantitative nanomechanics. Interfacial nanobubbles were formed and imaged on silicon nitride (Si3N4), mica, and highly ordered pyrolytic graphite (HOPG) substrates that were partly covered by reduced graphene oxide (rGO). The contact angles and sizes of those nanobubbles were measured under the same conditions. Nanobubbles with the same lateral width exhibited different heights on the different substrates, with the order Si3N4≈mica>rGO>HOPG, which is consistent with the trend of the hydrophobicity of the substrates. 相似文献
64.
Wei Li Shisheng Wang Jiatao Feng Yuansheng Xiao Xingya Xue Hui Zhang Yaqin Wang Xinmiao Liang 《Magnetic resonance in chemistry : MRC》2009,47(10):902-908
Thirteen curcuminoids (1–13) were isolated from the rhizomes of Curcuma longa. Among them, 1,5‐dihydroxy‐1,7‐bis(4‐hydroxyphenyl)‐4,6‐heptadiene‐3‐one (1), 1,5‐dihydroxy‐1‐(4‐hydroxy‐3‐methoxyphenyl)‐7‐(4‐hydroxyphenyl)‐4,6‐heptadiene‐3‐one (2), 1,5‐dihydroxy‐1‐(4‐hydroxyphenyl)‐7‐(4‐hydroxy‐3‐methoxyphenyl)‐4,6‐heptadiene‐3‐one (3), and 3‐hydroxy‐1,7‐bis‐(4‐hydroxyphenyl)‐6‐heptene‐1,5‐dione (4) are new compounds, and 1‐(4‐hydroxyphenyl)‐7‐(3, 4‐dihydroxyphenyl)‐1, 6‐heptadiene‐3, 5‐dione (5) is isolated from natural sources for the first time. The structures of these compounds were elucidated by extensive spectroscopic analyses, especially 1D and 2D NMR spectroscopy. The 13C NMR data and complete 1H and 13C NMR assignments of some known compounds are reported for the first time. In addition, the errors of 1H and 13C assignments reported in the literature were corrected. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
65.
66.
67.
A series of trivalent rare-earth element ions (europium, terbium, dysprosium) singly- and co-doped strontium yttrium borate phosphors was synthesized via the sol–gel method. The phase formation, luminescence properties, decay times, and energy transfer behaviors from terbium ions to europium ions, the thermal stability, and the Commission Internationale de L’Eclairage coordinates were investigated. Under the excitation of ultraviolet light, the singly doped phosphors exhibited green emission of terbium ions, white emission of dysprosium ions, and red emission of europium ions, respectively. For the terbium and europium ions co-doped strontium yttrium borate samples, a white emission can be realized by blending the doping concentration of terbium and europium ions. The critical distance between terbium and europium ions has been calculated to be about 14.52?Å and the energy transfer from terbium to europium occurred through the dipole–quadrupole interaction. At 150°C, the emission intensity of terbium and europium in the 12?mol% terbium and 14?mol% europium co-doped strontium yttrium borate sample was maintained at about 74% and 87% of their corresponding initial values, respectively, and the dysprosium ions singly doped strontium yttrium borate sample showed about 70% of its initial emission intensity at room temperature. The above results suggested that europium, terbium, dysprosium ions singly- and co-doped strontium yttrium borate phosphors have potential applications as ultraviolet-convertible phosphors. 相似文献
68.
葛根提取物高效液相色谱分析方法的优化 总被引:2,自引:0,他引:2
针对葛根提取物的复杂体系,分别从色谱模式、流动相、添加剂以及梯度洗脱条件几个方面对其高效液相色谱分析 方法进行了优化。其中梯度洗脱条件的优化是根据各组分在5次线性梯度下的保留时间并借助于CSASS软件快速准确地计 算出各组分的液相色谱保留参数a,c值以及峰形参数σ和τ,在此基础上使用CSASS软件对葛根提取物的色谱分离情况进行 高精度仿真预测,从而优化了梯度洗脱条件。考察了优化条件下的分析方法的精密度和重现性,结果表明该方法稳定、可 靠、重现性好。 相似文献
69.
Dr. Ranwen Ou Prof. Jing Wei Chen Zhao Dr. Qinfen Gu Dr. Haijin Zhu Xingya Li Nhi Sa Nguyen Dr. Li Wan Prof. Maria Forsyth Prof. Huanting Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12281-12287
The conversion of renewable plant polyphenol to advanced materials with tailorable properties and various functions is desirable and challenging. In this work, monovalent cation-phenolic crystals contained K+ or Na+ ions were synthesized by using plant polyphenol as an organic source in alkaline solution. The crystal structure was resolved, showing a laminar crystal structure with M+ as connecting nodes. The morphologies (e.g., rod-like and spindle-shaped) and chemical compositions of crystals could be tuned by changing the cations. Interestingly, these polymer crystals exhibited a pH-driven reversible crystal transformation. They transformed into their protonated crystalline form under acidic conditions (e.g., pH 2) and went back to the cation-bound crystalline form in alkaline solutions. Furthermore, the crystals proved excellent antioxidants and heavy metal ion adsorbents. 相似文献
70.
In contrast to earlier reports, It has been found that dibromoperfluoroalkanes actually can react spontaneously with PhOK, yielding fluoroalkyl phenyl ethers as products. Evidence for an anionic chain mechanism involving a bromophilic attack by the phenoxide ion is presented. 相似文献