全文获取类型
收费全文 | 1636篇 |
免费 | 87篇 |
国内免费 | 25篇 |
专业分类
化学 | 1027篇 |
晶体学 | 4篇 |
力学 | 93篇 |
数学 | 257篇 |
物理学 | 367篇 |
出版年
2024年 | 4篇 |
2023年 | 13篇 |
2022年 | 49篇 |
2021年 | 44篇 |
2020年 | 78篇 |
2019年 | 54篇 |
2018年 | 58篇 |
2017年 | 48篇 |
2016年 | 103篇 |
2015年 | 82篇 |
2014年 | 104篇 |
2013年 | 140篇 |
2012年 | 142篇 |
2011年 | 154篇 |
2010年 | 107篇 |
2009年 | 72篇 |
2008年 | 63篇 |
2007年 | 77篇 |
2006年 | 74篇 |
2005年 | 45篇 |
2004年 | 52篇 |
2003年 | 38篇 |
2002年 | 36篇 |
2001年 | 20篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1930年 | 1篇 |
1925年 | 1篇 |
排序方式: 共有1748条查询结果,搜索用时 403 毫秒
991.
Firoozzadeh Mohammad Shiravi Amir Hossein Shafiee Mojtaba 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1239-1251
Journal of Thermal Analysis and Calorimetry - Increasing the temperature of photovoltaic (PV) cells decreases their electricity generation. The use of phase change materials (PCMs) is one of the... 相似文献
992.
Shiravi Amir Hossein Shafiee Mojtaba Firoozzadeh Mohammad Bostani Hadis Bozorgmehrian Maryam 《Journal of Thermal Analysis and Calorimetry》2021,145(2):597-607
Journal of Thermal Analysis and Calorimetry - The convective heat transfer coefficient (CHTC) of a fluid is one of the most effective factors on the performance of a fluid in heat transfer... 相似文献
993.
Najibi Amir Alizadeh Parisa Ghazifard Payman 《Journal of Thermal Analysis and Calorimetry》2021,146(5):1971-1982
Journal of Thermal Analysis and Calorimetry - In this study, nonlinear transient thermo-elastic analysis for a thick hollow 1D-FGM (functionally graded material) axisymmetric cylinder with finite... 相似文献
994.
Yingwei Ouyang Amir Masoud Pourrahimi Anja Lund Xiangdong Xu Thomas Gkourmpis Per-Ola Hagstrand Christian Müller 《Journal of polymer science. Part A, Polymer chemistry》2021,59(11):1084-1094
The impact of a small amount of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) on the thermomechanical and electrical properties of blends comprising low-density polyethylene (LDPE) and isotactic polypropylene (PP) is investigated. SEBS is found to assemble at the PP:LDPE interface as well as within isolated PP domains. The addition of 10 wt% SEBS significantly increases the storage modulus between the melting temperatures of the two polyolefins, 110 and 160°C, and results in improved resistance to creep during both tensile deformation as well as compression. Furthermore, the ternary blends display a very low direct-current (DC) conductivity as low as 3.4 × 10−15 S m−1 at 70°C and 30 kV mm−1, which is considerably lower than values measured for neat LDPE. The here presented type of ternary blend shows potential as an insulation material for high-voltage direct current power cables. 相似文献
995.
Hossein Eshghi Ali Javid Amir Khojastehnezhad Farid Moeinpour Fatemeh F.Bamoharram Mehdi Bakavoli Masoud Mirzaei 《催化学报》2015,(3):299-307
A novel magnetic acidic catalyst comprising Preyssler(H14[Na P5W30O110]) heteropoly acid support‐ed on silica coated nickel ferrite nanoparticles (Ni Fe2O4@Si O2) was prepared.The catalyst was characterized by Fourier transform infrared,scanning electron microscopy,transmission electron microscopy,X‐ray diffraction,energy dispersive spectrum,VSM and particle size neasurement.Its catalytic activity was investigated for the synthesis of bis(dihydropyrimidinone)benzene and 3,4‐dihydropyrimidin‐2(1H)‐ones derivatives by the Biginelli reaction.With the catalyst,the reac‐tions occurred in less than 1 h with good to excellent yields.More importantly,the catalyst was easily separated from the reaction mixture by an external magnet and reused at least five times without degradation in the activity. 相似文献
996.
Supramolecular Translation of Enzymatically Triggered Disassembly of Micelles into Tunable Fluorescent Responses
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Marina Buzhor Assaf J. Harnoy Dr. Einat Tirosh Ayana Barak Dr. Tal Schwartz Dr. Roey J. Amir 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15633-15638
The need for advanced fluorescent imaging and delivery platforms has motivated the development of smart probes that change their fluorescence in response to external stimuli. Here a new molecular design of fluorescently labeled PEG–dendron hybrids that self‐assemble into enzyme‐responsive micelles with tunable fluorescent responses is reported. In the assembled state, the fluorescence of the dyes is quenched or shifted due to intermolecular interactions. Upon enzymatic cleavage of the hydrophobic end‐groups, the labeled polymeric hybrids become hydrophilic, and the micelles disassemble. This supramolecular change is translated into a spectral response as the dye–dye interactions are eliminated and the intrinsic fluorescence is regained. We demonstrate the utilization of this molecular design to generate both Turn‐On and spectral shift responses by adjusting the type of the labeling dye. This approach enables transformation of non‐responsive labeling dyes into smart fluorescent probes. 相似文献
997.
Chunhong Ye Svetoslav V. Nikolov Rossella Calabrese Amir Dindar Alexander Alexeev Bernard Kippelen David L. Kaplan Vladimir V. Tsukruk 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(29):8610-8613
We have demonstrated the facile formation of reversible and fast self‐rolling biopolymer microstructures from sandwiched active–passive, silk‐on‐silk materials. Both experimental and modeling results confirmed that the shape of individual sheets effectively controls biaxial stresses within these sheets, which can self‐roll into distinct 3D structures including microscopic rings, tubules, and helical tubules. This is a unique example of tailoring self‐rolled 3D geometries through shape design without changing the inner morphology of active bimorph biomaterials. In contrast to traditional organic‐soluble synthetic materials, we utilized a biocompatible and biodegradable biopolymer that underwent a facile aqueous layer‐by‐layer (LbL) assembly process for the fabrication of 2D films. The resulting films can undergo reversible pH‐triggered rolling/unrolling, with a variety of 3D structures forming from biopolymer structures that have identical morphology and composition. 相似文献
998.
Jeffrey Luo Huibin Chang Amir A. Bakhtiary Davijani H. Clive Liu Po-Hsiang Wang Robert J. Moon Satish Kumar 《Cellulose (London, England)》2017,24(4):1745-1758
Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were produced with up to 40 wt% CNC loading through the solution casting method. The rheological properties of the solution/suspensions and the structural, optical, thermal, and mechanical properties of the resulting films were investigated. The viscosity of the composite suspensions increased with higher CNC loadings and with longer aging times. PAN-co-MAA/CNC films maintained a similar level of optical transparency even with up to 40 wt% CNC loading. The glass transition temperature (Tg) increased from 92 to 118 °C, and the composites had higher thermal stability below 350 °C compared to both neat PAN-co-MAA and neat CNC. The mechanical properties also increased with higher CNC loadings, elastic modulus increased from 2.2 to 3.7 GPa, tensile strength increased from 75 to 132 MPa, and the storage modulus increased from 3.9 to 10.5 GPa. Using the Kelly and Tyson model the interfacial shear strength between the PAN-co-MAA and CNC was calculated to be 27 MPa. 相似文献
999.
Amir Ban 《Journal of Graph Theory》2017,86(2):250-254
We solve the following problem: Can an undirected weighted graph G be partitioned into two nonempty induced subgraphs satisfying minimum constraints for the sum of edge weights at vertices of each subgraph? We show that this is possible for all constraints satisfying , for every vertex x , where are, respectively, the sum and maximum of incident edge weights. 相似文献
1000.
In this article, we study the weak dissipative Kirchhoff equation \({u_{tt}} - M\left( {\left\| {\nabla u} \right\|_2^2} \right)\Delta u + b\left( x \right){u_t} + f\left( u \right) = 0\), under nonlinear damping on the boundary \(\frac{{\partial u}}{{\partial v}} + \alpha \left( t \right)g\left( {{u_t}} \right) = 0\). We prove a general energy decay property for solutions in terms of coefficient of the frictional boundary damping. Our result extends and improves some results in the literature such as the work by Zhang and Miao (2010) in which only exponential energy decay is considered and the work by Zhang and Huang (2014) where the energy decay has been not considered. 相似文献