全文获取类型
收费全文 | 97960篇 |
免费 | 3788篇 |
国内免费 | 2825篇 |
专业分类
化学 | 38791篇 |
晶体学 | 1035篇 |
力学 | 7982篇 |
综合类 | 221篇 |
数学 | 33910篇 |
物理学 | 22634篇 |
出版年
2024年 | 43篇 |
2023年 | 465篇 |
2022年 | 491篇 |
2021年 | 698篇 |
2020年 | 846篇 |
2019年 | 819篇 |
2018年 | 10923篇 |
2017年 | 10715篇 |
2016年 | 6943篇 |
2015年 | 1794篇 |
2014年 | 1401篇 |
2013年 | 1732篇 |
2012年 | 5609篇 |
2011年 | 12336篇 |
2010年 | 6856篇 |
2009年 | 7143篇 |
2008年 | 7860篇 |
2007年 | 9978篇 |
2006年 | 1400篇 |
2005年 | 2337篇 |
2004年 | 2270篇 |
2003年 | 2614篇 |
2002年 | 1603篇 |
2001年 | 702篇 |
2000年 | 738篇 |
1999年 | 671篇 |
1998年 | 589篇 |
1997年 | 538篇 |
1996年 | 539篇 |
1995年 | 433篇 |
1994年 | 397篇 |
1993年 | 349篇 |
1992年 | 257篇 |
1991年 | 269篇 |
1990年 | 236篇 |
1989年 | 174篇 |
1988年 | 148篇 |
1987年 | 149篇 |
1986年 | 120篇 |
1985年 | 95篇 |
1984年 | 86篇 |
1983年 | 60篇 |
1982年 | 66篇 |
1981年 | 56篇 |
1980年 | 59篇 |
1979年 | 44篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
12.
13.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
14.
Unsymmetrical Pyrene‐Fused Phthalocyanine Derivatives: Synthesis,Structure, and Properties 下载免费PDF全文
Houhe Pan Chao Chen Kang Wang Prof. Dr. Wenjun Li Prof. Dr. Jianzhuang Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3168-3173
Novel pyrene‐fused unsymmetrical phthalocyanine derivatives 2,3,9,10,16,17‐hexakis(2,6‐dimethylphenoxy)‐22,25‐diaza(2,7‐di‐tert‐butylpyrene)[4,5]phthalocyaninato zinc complex Zn[Pc(Pz‐pyrene)(OC8H9)6] ( 1 ) and 2,3,9,10‐tra(2,6‐dimethylphenoxy)‐15,18,22,25‐traza(2,7‐di‐tert‐butylpyrene)[4,5]phthalocyaninato zinc compound Zn[Pc(Pz‐pyrene)2(OC8H9)4] ( 2 ) were isolated for the first time. These unsymmetrical pyrene‐fused phthalocyanine derivatives have been characterized by a wide range of spectroscopic and electrochemical methods. In particular, the pyrene‐fused phthalocyanine structure was unambiguously revealed on the basis of single crystal X‐ray diffraction analysis of 1 , representing the first structurally characterized phthalocyanine derivative fused with an aromatic moiety larger than benzene. 相似文献
15.
Dr. Qing Xu Dr. Shanshan Tao Dr. Qiuhong Jiang Prof. Donglin Jiang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4587-4593
A strategy based on covalent organic frameworks for ultrafast ion transport involves designing an ionic interface to mediate ion motion. Electrolyte chains were integrated onto the walls of one-dimensional channels to construct ionic frameworks via pore surface engineering, so that the ionic interface can be systematically tuned at the desired composition and density. This strategy enables a quantitative correlation between interface and ion transport and unveils a full picture of managing ionic interface to achieve high-rate ion transport. Moreover, the effect of interfaces was scaled on ion transport; ion mobility is increased in an exponential mode with the ionic interface. This strategy not only sets a benchmark system but also offers a general guidance for designing ionic interface that is key to systems for energy conversion and storage. 相似文献
16.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
17.
18.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of... 相似文献
19.
This minireview describes the strategies for synthesis of fiuorinated surfactants potentially nonbioaccumulable.Various strategies have been focused on(Ⅰ) reducing the length of the perfluorocarbon chain,(Ⅱ) introducing hetero atoms into the fluorocarbon chain,(Ⅲ) introducing branch(herein and after branch means the fluoro-carbon chain section is not straight).In most cases,the surface tensions versus the surfactant concentrations have been assessed.These above strategies led to various highly fiuorinated(perfluorinated or not perfluorinated) surfactants whose chemical changes enabled to obtain novel alternatives to perfluorooctanoic acid(PFOA) and perfluorooctane sulphonate(PFOS). 相似文献
20.