全文获取类型
收费全文 | 11718篇 |
免费 | 2069篇 |
国内免费 | 2650篇 |
专业分类
化学 | 8961篇 |
晶体学 | 205篇 |
力学 | 764篇 |
综合类 | 219篇 |
数学 | 1611篇 |
物理学 | 4677篇 |
出版年
2024年 | 35篇 |
2023年 | 257篇 |
2022年 | 491篇 |
2021年 | 489篇 |
2020年 | 549篇 |
2019年 | 528篇 |
2018年 | 429篇 |
2017年 | 481篇 |
2016年 | 614篇 |
2015年 | 661篇 |
2014年 | 699篇 |
2013年 | 972篇 |
2012年 | 872篇 |
2011年 | 979篇 |
2010年 | 773篇 |
2009年 | 756篇 |
2008年 | 845篇 |
2007年 | 736篇 |
2006年 | 696篇 |
2005年 | 625篇 |
2004年 | 499篇 |
2003年 | 410篇 |
2002年 | 467篇 |
2001年 | 383篇 |
2000年 | 345篇 |
1999年 | 280篇 |
1998年 | 218篇 |
1997年 | 162篇 |
1996年 | 171篇 |
1995年 | 128篇 |
1994年 | 139篇 |
1993年 | 118篇 |
1992年 | 92篇 |
1991年 | 110篇 |
1990年 | 99篇 |
1989年 | 51篇 |
1988年 | 50篇 |
1987年 | 47篇 |
1986年 | 39篇 |
1985年 | 43篇 |
1984年 | 23篇 |
1983年 | 24篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1976年 | 1篇 |
1971年 | 2篇 |
1957年 | 3篇 |
1936年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
Flame retardancy and mechanical properties of poly(decamethylene terephthalamide) (PA10T) containing aluminum diethlyphosphinate (BEPAL) were investigated. The influence of BEPAL on the thermal degradation behavior of PA10T was studied using thermogravimetry, flammability test and chemical analysis. A decomposition model was given on the basis of Lewis acid-base interaction. The introduction of BEPAL led to reduced decomposition temperature, while the limiting oxygen index was greatly improved. The investigation of mechanical properties of PA10T/BEPAL composites indicated that the tensile strength firstly increased when low content BEPAL was added, then decreased with further increasing the concentration of BEPAL due to the agglomeration of filler particles. Dynamic mechanical analysis (DMA) results revealed that the presence of BEPAL hindered the movement of molecular chain. 相似文献
962.
Analytic Solution for Magnetohydrodynamic Stagnation Point Flow towards a Stretching Sheet
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A steady two-dimensional magnetohydrodynamic stagnation point flow towards a stretching sheet with variable surface temperature is investigated. The analytic solution is obtained by homotopy analysis method. The convergence region is computed and the feature of the solution is discussed. 相似文献
963.
Evolution of concentration fluctuation during phase separation of polystyrene/poly(vinyl methyl ether) blend in the presence of nanosilica
下载免费PDF全文
![点击此处可从《Journal of Polymer Science.Polymer Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Qi Chen Min Zuo Ruiquan Yang Jifei Zhang Xiong Lv Wenjing Zhang Yihu Song Qiang Zheng 《Journal of Polymer Science.Polymer Physics》2017,55(17):1337-1349
The influence of nanosilica on the concentration fluctuation of polystyrene/poly (vinyl methyl ether) (PS/PVME) mixtures was investigated during phase separation. The amplitude of concentration fluctuation was quantified by dielectric spectrums based on the idea of Lodge–Mcleish model and the linearized Cahn–Hilliard theory could describe the amplitude evolution of concentration fluctuation at the early stage of phase separation. Hydrophilic nanosilica A200 dispersed in PVME‐rich phase behaved an obvious inhibition effect on the concentration fluctuation of blend matrix, while hydrophobic nanosilica R974 dispersed in PS‐rich phase had little effect on the concentration fluctuation. The kinetics and amplitude evolution of concentration fluctuation during phase separation for PS/PVME/A200 nanocomposites were remarkably restrained due to the surface adsorption of PVME on A200. As the segmental dynamics of PVME and PS in homogeneous matrix was hardly influenced by A200 and R974, the enhanced miscibility and the significantly constrained flow relaxation of PVME chains might contribute to the retarded concentration fluctuation of PS/PVME/A200 nanocomposites. While the weak interaction between R974 and components of blend matrix and little effect of R974 on the molecular dynamics of PS chains may result in the weak retardation of concentration fluctuation for blend matrix. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1337–1349 相似文献
964.
965.
A consecutive radical addition‐coupling reaction involving dithioester is applied to produce thermodegradable multisegmented polymer using α,ω‐dibromo polymer as precursor. The macroradical generated by single electron transfer process promoted by Cu/ligand from α,ω‐dibromo polymer can efficiently add to ethyl dithiobenzoate, which results intermediate adduct radical. The in situ formed adduct radical immediately undergoes crosscoupling reaction with macroradical, generating segmented polymer bridged with C? S bond. The consecutive radical addition‐coupling reaction generates multisegmented polymer linked by C? S bond following step‐growth mechanism. The multisegmented polymer can be thermodegraded in the presence of hydrogen atom donor or air. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
966.
967.
Covalently Assembled Dipeptide Nanospheres as Intrinsic Photosensitizers for Efficient Photodynamic Therapy in Vitro
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)
Xiaoke Yang Jinbo Fei Qi Li Prof. Dr. Junbai Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6477-6481
Monodispersed diphenylalanine‐based nanospheres with excellent biocompatibility are fabricated through a facile covalent reaction‐induced assembly. Interestingly, the nanospheres exhibit red autofluorescence. Most importantly, such assembled dipeptide nanospheres can serve as intrinsic photosensitizer to convert O2 to singlet oxygen (1O2). Thus, photodynamic therapy in vitro can be achieved effectively. The versatile strategy could be extended to other biomolecules containing a primary amine group for the fabrication of potential intrinsic photosensitizers. 相似文献
968.
969.
Reduced Graphene‐Wrapped MnO2 Nanowires Self‐Inserted with Co3O4 Nanocages: Remarkable Enhanced Performances for Lithium‐Ion Anode Applications
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)
Qi Zhu Yunhui Li Prof. Ying Gao Prof. Xiao Wang Prof. Shuyan Song 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6876-6880
A simple synthetic approach for graphene‐templated nanostructured MnO2 nanowires self‐inserted with Co3O4 nanocages is proposed in this work. The Co3O4 nanocages were penetrated in situ by MnO2 nanowires. As an anode, the as‐obtained MnO2–Co3O4–RGO composite exhibits remarkable enhanced performance compared with the MnO2–RGO and Co3O4–RGO samples. The MnO2–Co3O4–RGO electrode delivers a reversible capacity of up to 577.4 mA h g?1 after 400 cycles at 500 mA g?1 and the Coulombic efficiency of MnO2–Co3O4–RGO is about 96 %. 相似文献
970.