全文获取类型
收费全文 | 102篇 |
免费 | 4篇 |
专业分类
化学 | 68篇 |
力学 | 3篇 |
数学 | 11篇 |
物理学 | 24篇 |
出版年
2022年 | 13篇 |
2021年 | 8篇 |
2020年 | 1篇 |
2019年 | 12篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 1篇 |
2012年 | 6篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 3篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有106条查询结果,搜索用时 31 毫秒
11.
12.
13.
Miftakhul Huda Keigo Minamisawa Takamasa Tsukamoto Makoto Tanabe Kimihisa Yamamoto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(4):1014-1018
Subnanocatalysts (SNCs) containing various noble metals (Cu, Ru, Rh, Pd, or Pt) with sizes of approximately 1 nm were synthesized using dendritic poly(phenylazomethine)s as a macromolecular template. These materials exhibit high catalytic performance during toluene oxidation without the use of harmful solvents or explosive oxidants, resulting in the formation of valuable organic products, including benzoic acid as the major product. In particular, Pt19 SNC with a narrow particle size distribution exhibits extraordinary catalytic activity, with a turnover frequency of 3238 atom?1 h?1, which is 1700 times greater than that obtained by commercial Pt/C catalysts. 相似文献
14.
Schabas G Wang CW Oskooei A Yusuf H Moffitt MG Sinton D 《Langmuir : the ACS journal of surfaces and colloids》2008,24(19):10596-10603
The controlled self-assembly of polymer-stabilized quantum dots (QDs) into mesoscale aqueous spherical assemblies termed quantum dot compound micelles (QDCMs) using a two-phase gas-segmented microfluidic reactor is described. Self-assembly is initiated by the fast mixing of water (approximately 1 s) with a blend solution of polystyrene-coated QDs and amphiphilic polystyrene-block-poly(acrylic acid) stabilizing chains via chaotic advection within liquid plugs moving through a sinusoidal channel. Subsequent recirculating flow within a post-formation channel subjects the dynamic QDCMs to shear-induced processing, controlled via the flow rate and channel length, before a final quench into pure water. During processing, larger QDCMs within the initial population undergo breakup into smaller particles, resulting in smaller mean particle sizes, smaller relative standard deviations, and more skewed distribution shapes, as the overall shear exposure is increased. For these cases, shear-induced size reduction is sufficient to dominate surface tension-driven growth. 相似文献
15.
16.
Yusuf H Kim WG Lee DH Aloshyna M Brolo AG Moffitt MG 《Langmuir : the ACS journal of surfaces and colloids》2007,23(10):5251-5254
We demonstrate a new hierarchical self-assembly strategy for the formation of photonic arrays containing quantum dots (QDs), in which sequential self-assembly steps introduce organization on progressively longer length scales, ranging from the nanoscale to the microscale regimes. The first step in this approach is the self-assembly of diblock copolymers to form block ionomer reverse micelles (SA1); within each micelle core, a single CdS QD is synthesized to yield the hybrid building block BC-QD. Once SA1 is completed, the hydrophobic BD-QD building blocks are blended with amphiphilic block copolymer stabilizing chains in an organic solvent; water addition induces secondary self-assembly (SA2) to form quantum dot compound micelles (QDCMs). Finally, aqueous dispersions of QDCMs are slowly evaporated to induce the formation of three-dimensional (3D) close-packed arrays in a tertiary self-assembly step (SA3). The resulting hierarchical assemblies, consisting of a periodic array of hybrid spheres each containing multiple CdS QDs, exhibit the collective property of a photonic stop band, along with photoluminescence arising from the constituent QDs. A high degree of structural control is possible at each level of organization by judicious selection of experimental variables, allowing various parameters governing the collective optical properties, including QD size, nanoparticle spacing, and mesocale periodicity, to be independently tuned. The resulting control over optical properties via successive self-assembly steps should provide new opportunities for hierarchical materials for QD lasers and all-optical switching. 相似文献
17.
Mustapha Muhammad Huda M. Alshanbari Ayed R. A. Alanzi Lixia Liu Waqas Sami Christophe Chesneau Farrukh Jamal 《Entropy (Basel, Switzerland)》2021,23(11)
In this article, we propose the exponentiated sine-generated family of distributions. Some important properties are demonstrated, such as the series representation of the probability density function, quantile function, moments, stress-strength reliability, and Rényi entropy. A particular member, called the exponentiated sine Weibull distribution, is highlighted; we analyze its skewness and kurtosis, moments, quantile function, residual mean and reversed mean residual life functions, order statistics, and extreme value distributions. Maximum likelihood estimation and Bayes estimation under the square error loss function are considered. Simulation studies are used to assess the techniques, and their performance gives satisfactory results as discussed by the mean square error, confidence intervals, and coverage probabilities of the estimates. The stress-strength reliability parameter of the exponentiated sine Weibull model is derived and estimated by the maximum likelihood estimation method. Also, nonparametric bootstrap techniques are used to approximate the confidence interval of the reliability parameter. A simulation is conducted to examine the mean square error, standard deviations, confidence intervals, and coverage probabilities of the reliability parameter. Finally, three real applications of the exponentiated sine Weibull model are provided. One of them considers stress-strength data. 相似文献
18.
Al-Jubbori Mushtaq Abed Kassim Huda H. Radhi Fahmi Sh. Attarzadeh Amin Hossain I. Ahmed Imad M. Sharrad Fadhil I. 《Physics of Atomic Nuclei》2019,82(3):201-211
Physics of Atomic Nuclei - The even—even rare-earth nuclei in U(5)—SU(3) region at neutron number (N) = 90, have been systematically studied using the Bohr—Mottelson Model (BM),... 相似文献
19.
Anhar Abdel-Aziem Huda Refaat Mahmoud Rashdan Entesar Mohamed Ahmed Sara N. Shabaan 《Green Chemistry Letters and Reviews》2019,12(1):9-18
In the present study, a rapid, less expensive, clean and environmental friendly route to synthesis new pyrazoles, pyrazolopyridazines and condensed pyrimidines was developed via grinding of 2-(3-(dimethylamino)acryloyl)-3H-benzo[f]chromen-3-one (1) with different reagents. All the new compounds were characterized and established using elemental analysis and spectral data. Eight compounds were selected for in vitro antiproliferative against different human cancer cell lines entitled melanoma, cancers of the lung, leukemia, breast, brain, colon, prostate, ovary and kidney by the USA NCI. 相似文献
20.
Nazmi A. Mohammed Huda S. Abo Elnasr Moustafa H. Aly 《Optical and Quantum Electronics》2014,46(2):295-304
This work describes an approach to design a $2\times 2$ optoelectronic switch based on the Mach–Zehnder interferometer with a channel profile of Titanium (Ti) diffused in Potassium niobate ( $\hbox {KNbO}_{3}$ ) at a wavelength of $1.3\,\upmu \hbox {m}$ . The evaluation parameters used are the insertion loss and the extinction ratio. The originality of this work is introducing the $\hbox {KNbO}_{3 }$ crystal as a host while optimizing the Ti strip thickness to provide a remarkable switching performance. Optimization leads to a lower switching voltage of 4 V, an insertion loss of 0.0261 dB and extinction ratio of 29.4 dB. The designed switch has a high switching capability and degree of reliability. 相似文献