全文获取类型
收费全文 | 132篇 |
免费 | 8篇 |
国内免费 | 4篇 |
专业分类
化学 | 116篇 |
晶体学 | 5篇 |
力学 | 2篇 |
综合类 | 2篇 |
数学 | 3篇 |
物理学 | 16篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 4篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 7篇 |
2011年 | 16篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 8篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1977年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有144条查询结果,搜索用时 234 毫秒
101.
We report successful synthesis of zinc ferrite nanoparticles (ZFs) by a facile low-temperature (90 °C) solution-based process from ferric nitrate nonahydrate and zinc nitrate hexahydrate precursors in presence of hydrazine hydrate. X-ray diffraction analysis and transmission electron microscopy confirmed the presence of ZFs, which were further characterized by Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric measurements for identification of characteristic chemical bond vibrations and thermal weight loss behavior, respectively. Measurements of magnetic properties at room temperature revealed that the sample showed quite high saturation magnetization (22.0 emu/g at ~19,200 G), implying the presence of less impurities/surface defects in the ZFs. The material also showed zero coercivity as a soft-magnetic material. The protein adsorption performance of the ZFs was checked using bovine serum albumin (BSA) as model protein. Excellent protein adsorption capacity of 210 mg/g (close to the value of 218.81 mg/g calculated using the Langmuir model) for BSA concentration of 0.3 mg/mL was obtained at optimized solution pH of 5. This simple process could be adopted for synthesis of different magnetic nanomaterials for use in biomedical applications. 相似文献
102.
Feixiang Cheng Jishu Chen Fan Wang Ning Tang Longhai Chen 《Transition Metal Chemistry》2011,36(5):573-578
Two polypodands, tetrakis[2-(4,5-diazafluoren-9-ylimino)phenoxymethyl]methane (L1) and 1,1,1-tris[2-(4,5-diazafluoren-9-ylimino)phenoxymethyl]propane (L2), and their corresponding Ru(II) polypyridyl complexes have been synthesized and characterized. The photophysical behaviors
of the two complexes were investigated by UV–vis absorption and emission spectroscopy. They display metal-to-ligand charge
transfer (MLCT) absorptions at around 443 nm in MeCN solution at room temperature and emission at around 573 nm in EtOH:MeOH
(4:1) glassy matrix at 77 K. Electrochemical studies of the two complexes show one Ru(II)-centered oxidation at around 1.35 V
and three ligand-centered reductions. 相似文献
103.
Sayani Nandy Debtosh Kundu Milan Kanti Naskar 《Journal of Sol-Gel Science and Technology》2014,72(1):49-55
The effect of secondary (diethanolamine) and tertiary (triethanolamine) alkanolamines as catalysts on the formation of mesoporous Stöber silica nanoparticles by sol–gel method was studied. The particles were characterized by thermogravimetry and differential thermal analysis, Fourier transform infrared spectroscopy, N2 physisorption measurements, and field emission scanning electron microscopy. By using ammonia and different alkanolamines as catalysts, the Brunauer–Emmet–Teller (BET) surface area and pore volume increased in the order of ammonia < diethanolamine < triethanolamine. A maximum BET surface area of 140.1 m2 g?1 and pore volume of 0.66 cm3 g?1 were obtained from triethanolamine catalyzed silica particles. The average particle size of silica prepared by ammonia and different alkanolamines as catalysts decreased in the order of ammonia > diethanolamine > triethanolamine. The role of different alkanolamines on the textural properties and particle size of silica is explained in terms of their relative steric hindrance and basicity. 相似文献
104.
105.
Deb Argha Gazi Mahasin Bhoumik Gopa Naskar Arindam Barman Chiranjib 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):375-384
Air radon survey was carried out at different underground locations at Kolkata using radon monitor. Average radon concentration for basements was found to be 22.70 ± 1.12 Bq/m3 with maximum 59.00 ± 7.18 Bq/m3 and minimum 8.50 ± 3.14 Bq/m3. Average level for sub-ways was 23.05 ± 2.59 Bq/m3 fluctuating between maximum 39.00 ± 1.24 Bq/m3 and minimum 13.50 ± 1.78 Bq/m3. In comparison, open air background at basement entrance was 19.44 ± 1.06 Bq/m3 and subway entrance was 18.58 ± 1.14 Bq/m3. Annual effective dose was calculated to assess probable health risk. Radon concentration level and annual effective dose were found well below safe levels recommended by International Agencies WHO and UNSCEAR.
相似文献106.
Temperature‐dependent self‐assembly and rheological behavior of a thermoreversible pmma–PnBA–PMMA triblock copolymer gel 下载免费PDF全文
Ramiz Boy Keisha B. Walters Amit K. Naskar Santanu Kundu 《Journal of Polymer Science.Polymer Physics》2017,55(11):877-887
Self‐assembly and mechanical properties of triblock copolymers in a mid‐block selective solvent are of interest in many applications. Herein, we report physical assembly of an ABA triblock copolymer, [PMMA–Pn BA–PMMA] in two different mid‐block selective solvents, n‐butanol and 2‐ethyl‐1‐hexanol. Gel formation resulting from end‐block associations and the corresponding changes in mechanical properties have been investigated over a temperature range of ?80 °C to 60 °C, from near the solvent melting points to above the gelation temperature. Shear‐rheometry, thermal analysis, and small‐angle neutron scattering data reveal formation and transition of structure in these systems from a liquid state to a gel state to a percolated cluster network with decrease in temperature. The aggregated PMMA end‐blocks display a glass transition temperature. Our results provide new understanding into the structural changes of a self‐assembled triblock copolymer gel over a large length scale and wide temperature range. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 877–887 相似文献
107.
A high-yielding environmentally benign protocol has been developed for the synthesis of 3-(pyrrol-1-yl)-indolin-2-ones from the reaction of isatin and trans-4-hydroxy-L-proline in aqueous micellar medium. The method is operationally simple and more effective than the previous methods in terms of the yield of the products and the reaction time. 相似文献
108.
研究了戊二酸钛(Ⅲ)在空气、氮气下的热分解反应,从TG曲线求出热分解反应的表观动力学参数反应级数n,活化能Ea,频率因子A 相似文献
109.
本文提出了一种通过多重成象系统直接利用象平面内积运算用实值函数简单地实现关联存储器的方法,文中分析了这种关联存储器的基本原理,并给出了实验结果。 相似文献
110.
Milan Kanti Naskar Debtosh Kundu Minati Chatterjee 《Journal of Sol-Gel Science and Technology》2012,64(1):117-123
The support substrates were modified with sol?Cgel-based silica coating as intermediate buffer layer followed by NaA zeolite seed (prepared hydrothermally at 85?°C for 3?h) coating with 2?wt% aqueous dispersion. The secondary crystallization of NaA zeolite in the silica-seed-coated supports was carried out hydrothermally through crystal growth process at 65?°C for 4 and 8?h (single-stage each), (6?+?4) and (6?+?6)?h (double-stage each), and (6?+?4?+?2) and (6?+?4?+?4)?h (triple-stage each). The crystallization behaviours of the prepared NaA membranes were studied by X-ray diffraction, and the microstructures of the same films were observed by field emission scanning electron microscope. The efficiency of the membranes was tested with gas permeation study. The double-stage secondary crystallization at 65?°C for (6?+?4)?h showed highly interlocked NaA grains in the membrane and it rendered the permeance values of 3.7?×?10?8?mol?m?2?s?1?Pa?1 and 15.9?×?10?8 for single gas, nitrogen (N2) and hydrogen (H2) respectively with the ideal selectivity of 4.3. 相似文献