全文获取类型
收费全文 | 1620篇 |
免费 | 85篇 |
国内免费 | 25篇 |
专业分类
化学 | 1020篇 |
晶体学 | 4篇 |
力学 | 87篇 |
数学 | 257篇 |
物理学 | 362篇 |
出版年
2024年 | 4篇 |
2023年 | 13篇 |
2022年 | 55篇 |
2021年 | 42篇 |
2020年 | 78篇 |
2019年 | 53篇 |
2018年 | 56篇 |
2017年 | 46篇 |
2016年 | 103篇 |
2015年 | 82篇 |
2014年 | 103篇 |
2013年 | 134篇 |
2012年 | 142篇 |
2011年 | 153篇 |
2010年 | 106篇 |
2009年 | 70篇 |
2008年 | 62篇 |
2007年 | 77篇 |
2006年 | 74篇 |
2005年 | 45篇 |
2004年 | 50篇 |
2003年 | 37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 | 2篇 |
1980年 | 2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1730条查询结果,搜索用时 15 毫秒
971.
Massoumi Bakhshali Farnoudiyan-Habibi Amir Jaymand Mehdi 《Journal of Solid State Electrochemistry》2017,21(2):611-611
Journal of Solid State Electrochemistry - 相似文献
972.
Hide Yasuhara Derek Elsworth Amir Polak Jishan Liu Avrami Grader Phillip Halleck 《Transport in Porous Media》2006,65(3):385-409
Principal mechanical and chemical processes contributing to the observed spontaneous switching from net decrease in permeability
to net increase in a fracture in carbonate are examined. The evolution of permeability, and related fracture aperture, is
represented through a lumped parameter model. The significant processes of pressure solution beneath bridging asperities,
transport of dissolved mass to the fracture void, and subsequent precipitation or dissolution within the fracture void enable
the principal characteristics of observed behavior to be followed. The evolution of dissolved mass concentration in the pore
fluid is followed for arbitrary applied stress, temperature, and pH conditions, with appropriate feedback to the evolution
of fracture permeability. Comparisons with experimental measurements in limestone (Polak et al., 2004, Water Resour. Res. Vol. 40, W03502, doi: 10.1029/2003GL017575) show satisfactory agreement for the evolution of fracture aperture and to a
lesser degree in calcium concentrations in the effluent pore fluid. Importantly, the spontaneous switching in permeability
change, from aperture reducing to aperture increasing, with no change in environmental conditions, is replicated without the
need for an ad hoc trigger. Although this switch is accurately replicated, the lumped parameter model is incapable of replicating the rapid
observed growth in permeability that directly follows. This inability results from the assumed form of the lumped asperity
model, that is incapable of representing the spatially distributed change in aperture that is seen to occur within the fracture.
Despite this inconsistency, the model is shown capable of representing the principal behaviors evident in the response. 相似文献
973.
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
974.
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
975.
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
976.
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
977.
Supramolecular Translation of Enzymatically Triggered Disassembly of Micelles into Tunable Fluorescent Responses 下载免费PDF全文
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
978.
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
979.
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
980.
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