全文获取类型
收费全文 | 561870篇 |
免费 | 6295篇 |
国内免费 | 2152篇 |
专业分类
化学 | 281477篇 |
晶体学 | 8164篇 |
力学 | 28059篇 |
综合类 | 8篇 |
数学 | 88055篇 |
物理学 | 164554篇 |
出版年
2020年 | 3494篇 |
2019年 | 3732篇 |
2018年 | 14183篇 |
2017年 | 13874篇 |
2016年 | 12846篇 |
2015年 | 5948篇 |
2014年 | 8009篇 |
2013年 | 22092篇 |
2012年 | 19897篇 |
2011年 | 29889篇 |
2010年 | 18646篇 |
2009年 | 18919篇 |
2008年 | 24700篇 |
2007年 | 26897篇 |
2006年 | 18403篇 |
2005年 | 17664篇 |
2004年 | 16401篇 |
2003年 | 15138篇 |
2002年 | 14035篇 |
2001年 | 15011篇 |
2000年 | 11597篇 |
1999年 | 9221篇 |
1998年 | 7625篇 |
1997年 | 7448篇 |
1996年 | 7397篇 |
1995年 | 6698篇 |
1994年 | 6403篇 |
1993年 | 6342篇 |
1992年 | 6797篇 |
1991年 | 6805篇 |
1990年 | 6347篇 |
1989年 | 6154篇 |
1988年 | 6507篇 |
1987年 | 6069篇 |
1986年 | 5807篇 |
1985年 | 8192篇 |
1984年 | 8363篇 |
1983年 | 6896篇 |
1982年 | 7311篇 |
1981年 | 7269篇 |
1980年 | 6960篇 |
1979年 | 7245篇 |
1978年 | 7279篇 |
1977年 | 7239篇 |
1976年 | 7206篇 |
1975年 | 6884篇 |
1974年 | 6796篇 |
1973年 | 6981篇 |
1972年 | 4460篇 |
1971年 | 3498篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Anfimov N. V. Vorobel V. Kovalev Yu. S. Kodyš P. 《Physics of Particles and Nuclei Letters》2019,16(6):820-825
Physics of Particles and Nuclei Letters - The Silicon Photomultiplier (SiPM) is a novel semiconducting photodetector which can detect single photons. It consists of many microcells (pixels)... 相似文献
92.
Amphiphilic block copolymer self‐assemblies of poly(NVP)‐b‐poly(MDO‐co‐vinyl esters): Tunable dimensions and functionalities 下载免费PDF全文
Guillaume G. Hedir A. Pitto‐Barry Andrew P. Dove Rachel K. O'Reilly 《Journal of polymer science. Part A, Polymer chemistry》2015,53(23):2699-2710
Functional, degradable polymers were synthesized via the copolymerization of vinyl acetate (VAc) and 2‐methylene‐1,3‐dioxepane (MDO) using a macro‐xanthate CTA, poly(N‐vinylpyrrolidone), resulting in the formation of amphiphilic block copolymers of poly(NVP)‐b‐poly(MDO‐co‐VAc). The behavior of the block copolymers in water was investigated and resulted in the formation of self‐assembled nanoparticles containing a hydrophobic core and a hydrophilic corona. The size of the resultant nanoparticles was able to be tuned with variation of the hydrophilic and hydrophobic segments of the core and corona by changing the incorporation of the macro‐CTA as well as the monomer composition in the copolymers, as observed by Dynamic Light Scattering, Static Light Scattering, and Transmission Electron Microscopy analyses. The concept was further applied to a VAc derivative monomer, vinyl bromobutanoate, to incorporate further functionalities such as fluorescent dithiomaleimide groups throughout the polymer backbone using azidation and “click” chemistry as postpolymerization tools to create fluorescently labeled nanoparticles. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2699–2710 相似文献
93.
94.
95.
96.
Analytical and Bioanalytical Chemistry - 相似文献
97.
Probing the Catalytic Activity of Reduced Graphene Oxide Decorated with Au Nanoparticles Triggered by Visible Light 下载免费PDF全文
Dr. Jiale Wang Dr. Fabiane J. Trindade Caroline B. de Aquino Joana C. Pieretti Prof. Dr. Sergio H. Domingues Prof. Dr. Romulo A. Ando Prof. Dr. Pedro H. C. Camargo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9889-9894
Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au NPs) were obtained by the in situ reduction of GO and AuCl4?(aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O2 through the transfer of SPR‐excited hot electrons to O2 molecules adsorbed from air. The SPR‐mediated catalytic oxidation of p‐aminothiophenol (PATP) to p,p′‐dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR‐mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge‐transfer processes from rGO to Au took place and contributed to improved SPR‐mediated activity. Since the transfer of electrons from Au to adsorbed O2 molecules is the crucial step for PATP oxidation, in addition to the SPR‐excited hot electrons of Au NPs, the transfer of electrons from rGO to Au contributed to increasing the electron density of Au above the Fermi level and thus the Au‐to‐O2 charge‐transfer process. 相似文献
98.
99.
100.
Thomas Wittmann Dr. Renée Siegel Nele Reimer Dr. Wolfgang Milius Prof. Dr. Norbert Stock Prof. Dr. Jürgen Senker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):314-323
The resistance of metal–organic frameworks towards water is a very critical issue concerning their practical use. Recently, it was shown for microporous MOFs that the water stability could be increased by introducing hydrophobic pendant groups. Here, we demonstrate a remarkable stabilisation of the mesoporous MOF Al‐MIL‐101‐NH2 by postsynthetic modification with phenyl isocyanate. In this process 86 % of the amino groups were converted into phenylurea units. As a consequence, the long‐term stability of Al‐MIL‐101‐URPh in liquid water could be extended beyond a week. In water saturated atmospheres Al‐MIL‐101‐URPh decomposed at least 12‐times slower than the unfunctionalised analogue. To study the underlying processes both materials were characterised by Ar, N2 and H2O sorption measurements, powder X‐ray diffraction, thermogravimetric and chemical analysis as well as solid‐state NMR and IR spectroscopy. Postsynthetic modification decreased the BET equivalent surface area from 3363 to 1555 m2 g?1 for Al‐MIL‐101‐URPh and reduced the mean diameters of the mesopores by 0.6 nm without degrading the structure significantly and reducing thermal stability. In spite of similar water uptake capacities, the relative humidity‐dependent uptake of Al‐MIL‐101‐URPh is slowed and occurs at higher relative humidity values. In combination with 1H‐27Al D ‐HMQC NMR spectroscopy experiments this favours a shielding mechanism of the Al clusters by the pendant phenyl groups and rules out pore blocking. 相似文献