全文获取类型
收费全文 | 120篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
化学 | 93篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 10篇 |
物理学 | 22篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 15篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2004年 | 2篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有131条查询结果,搜索用时 15 毫秒
41.
42.
43.
A series of methyl 4-(4-alkoxystyryl)benzoates was synthesised and studied for liquid crystalline and fluorescence properties. The peculiarity of the reaction scheme involved condensation between 4-alkoxybenzaldehyde and 4-(methoxycarbonyl)benzyltriphenyl phosphonium bromide in dichloromethane without any phase separation. The compounds were found thermally stable up to 200°C. The banded or arced focal-conic fan texture of CrE phase was exhibited on cooling the compounds (with chain length > C4) below the SmA phase. It was observed that increasing chain length up to C10 enhances mesophase stability. No LC behaviour was manifested by small (up to C3) and branched small chain (up to C4) members of the series. 相似文献
44.
Wajiha Khan Muhammad A. Abbasi Aziz-ur Rehman Sabahat Z. Siddiqui Majid Nazir Syed A. Ali Shah Hussain Raza Mubashir Hassan Muhammad Shahid Sung Y. Seo 《Journal of heterocyclic chemistry》2020,57(7):2955-2968
In the current paper, through a convergent multi-step approach, a library of novel indole-phenyltriazole hybrids containing an amide moiety ( 9a-k) was synthesized. The structural verification of all synthesized molecules was accomplished by CHN and spectral analyses data. These synthesized bi-heterocyclic derivatives ( 9a-k ) were evaluated for their anti-ulcer potential by inhibitory action against Jack bean urease enzyme and subsequently their structure-activity relationship was perceived. Moreover, these compounds were inspected for cytotoxic profile by hemolytic activity and it was professed that nearly all the synthesized compounds showed low cytotoxicity. In addition, free radical scavenging activity and kinetic analysis were also carried out for these compounds to understand their mode of inhibition. So, it was summated that these derivatives might lead to further research gateways for obtaining better and safe anti-ulcer agents. 相似文献
45.
Nazir M Saleem M Riaz N Hafeez M Sultan M Jabbar A Ali MS 《Natural product communications》2011,6(11):1651-1652
Two new rotenoids, boerharotenoids A (1) and B (2), and four known compounds, boeravinone (3), 5,7,3'-trihydroxycoumaronochromone (4), boeravinone F (5), and eupalitin-3-O-beta-D-galactopyranoside (6), have been isolated from Boerhavia repens and their structures established by spectroscopic (1D and 2D NMR) and mass spectrometric comparison with literature values. 相似文献
46.
Mojtaba Shamsipur Nazir Fattahi Meghdad Pirsaheb Kiomars Sharafi 《Journal of separation science》2012,35(20):2718-2724
Dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography‐ultraviolet detection as a fast and inexpensive technique was applied to the simultaneous extraction and determination of traces of three common herbicides, 2,4‐D, alachlor and atrazine, in aqueous samples. The critical experimental parameters, including type of the extraction and disperser solvents as well as their volumes, sample pH, salt addition, extraction time and centrifuging time, and speed were investigated and optimized. Under the optimum conditions, the calibration graphs found to be linear in the range of 0.3–200 μg/L with limits of detection in the range of 0.05–0.1 μg/L. The relative standard deviations were in the range of 4.5–6.2% (n = 7). The relative recoveries of well, tap, and river water samples which have been spiked with different levels of herbicides were 92.0–107.0, 82.0–104.0, and 82.0–86.0%, respectively. 相似文献
47.
Nekrasov-Okounkov identity gives a product representation of the sum over partitions of a certain function of partition hook length. In this paper, we give several generalizations of the Nekrasov-Okounkov identity using the cyclic symmetry of the topological vertex. 相似文献
48.
A. Shaukat Y. Saeed S. Nazir N. Ikram M. Tanveer 《Physica B: Condensed Matter》2009,404(21):3964-3972
Full-potential linearized augmented plane wave method (FP-LAPW) within density functional theory has been used to calculate structural, electronic and optical properties of Ca1−xSrxS, an alkali earth chalcogenide, with varying compositional parameter x in the range 0<x<1. Whereas the structural properties are discussed in terms of charge transfer between the two cations, calculated electronic band structure and density of states have been analyzed in terms of contribution from the S p, Ca d and Sr d states. Furthermore, we have calculated some optical properties such as real and imaginary parts of dielectric constant, ε(ω), and the calculated results have been discussed in comparison with the existing experimental data and other theoretical calculations. 相似文献
49.
Ramsay AJ Godden TM Boyle SJ Gauger EM Nazir A Lovett BW Fox AM Skolnick MS 《Physical review letters》2010,105(17):177402
We study optically driven Rabi rotations of a quantum dot exciton transition between 5 and 50 K, and for pulse areas of up to 14π. In a high driving field regime, the decay of the Rabi rotations is nonmonotonic, and the period decreases with pulse area and increases with temperature. By comparing the experiments to a weak-coupling model of the exciton-phonon interaction, we demonstrate that the observed renormalization of the Rabi frequency is induced by fluctuations in the bath of longitudinal acoustic phonons, an effect that is a phonon analogy of the Lamb shift. 相似文献
50.
Zohra Nazir Kayani Saira Riaz Saima Iram Shahzad Naseem 《Journal of Saudi Chemical Society》2019,23(4):392-396
Iron cobalt nickel nitride (FeCoNiN) thin films are prepared by sol-gel spin coating route. The structural, magnetic and surface properties of the thin films are evaluated. The crystalline nature of thin films was enhanced upon annealing, leading to increased crystallite size. The X-ray diffraction shows mixed phases with crystallite size in the range of 20–26.93 nm. Thin films show ferromagnetism at room temperature. Coercivity and saturation magnetization are in the range of 642–716 Oe and 2.5–7.5 emu/cm3 respectively. Both coercivity and saturation magnetization increased with annealing of thin films. Magnetic properties are related to the crystallinity of thin films. The increase in crystallite size results into an increase of magnetic properties. Rectangular shaped particles are seen on the surface of thin films. The same type of grains can be seen on the surface of thin films which confirmed the formation of FeCoNiN as predicted by XRD. These novel thin films might be used in memory devices and optoelectronic applications. 相似文献