全文获取类型
收费全文 | 256899篇 |
免费 | 2829篇 |
国内免费 | 903篇 |
专业分类
化学 | 130964篇 |
晶体学 | 4153篇 |
力学 | 11477篇 |
综合类 | 10篇 |
数学 | 29062篇 |
物理学 | 84965篇 |
出版年
2021年 | 2017篇 |
2020年 | 2182篇 |
2019年 | 2397篇 |
2018年 | 3163篇 |
2017年 | 3051篇 |
2016年 | 4600篇 |
2015年 | 2950篇 |
2014年 | 4632篇 |
2013年 | 11126篇 |
2012年 | 8835篇 |
2011年 | 10824篇 |
2010年 | 7524篇 |
2009年 | 7462篇 |
2008年 | 9935篇 |
2007年 | 9895篇 |
2006年 | 9338篇 |
2005年 | 8885篇 |
2004年 | 8345篇 |
2003年 | 7112篇 |
2002年 | 6720篇 |
2001年 | 7578篇 |
2000年 | 5877篇 |
1999年 | 4543篇 |
1998年 | 3819篇 |
1997年 | 3732篇 |
1996年 | 3607篇 |
1995年 | 3289篇 |
1994年 | 3232篇 |
1993年 | 3341篇 |
1992年 | 3448篇 |
1991年 | 3568篇 |
1990年 | 3269篇 |
1989年 | 3203篇 |
1988年 | 3230篇 |
1987年 | 3106篇 |
1986年 | 2950篇 |
1985年 | 3994篇 |
1984年 | 4178篇 |
1983年 | 3364篇 |
1982年 | 3560篇 |
1981年 | 3487篇 |
1980年 | 3369篇 |
1979年 | 3459篇 |
1978年 | 3575篇 |
1977年 | 3454篇 |
1976年 | 3555篇 |
1975年 | 3238篇 |
1974年 | 3254篇 |
1973年 | 3296篇 |
1972年 | 2278篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Probing the Catalytic Activity of Reduced Graphene Oxide Decorated with Au Nanoparticles Triggered by Visible Light
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)
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
102.
103.
Dr. Man-Bo Li Daniels Posevins Dr. Karl P. J. Gustafson Dr. Cheuk-Wai Tai Dr. Andrey Shchukarev Dr. Youai Qiu Dr. Jan-E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):210-215
A highly selective and efficient oxidative carbocyclization/borylation of enallenols catalyzed by palladium immobilized on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was developed for diastereoselective cyclobutenol synthesis. The heterogeneous palladium catalyst can be recovered and recycled without any observed loss of activity or selectivity. The high diastereoselectivity of the reaction is proposed to originate from a directing effect of the enallenol hydroxyl group. Optically pure cyclobutenol synthesis was achieved by the heterogeneous strategy by using chiral enallenol obtained from kinetic resolution. 相似文献
104.
Mathematical Notes - We prove the equivalence of a vector and a scalar equilibrium problem that naturally arise when studying the limit distribution of zeros of type I Hermite–Padé... 相似文献
105.
Lebedev V. T. Serebrov A. P. 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2020,14(1):1-5
Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - A method for studying the magnetic dynamics of endofullerenes M@C2n (2n = 60, 70, …) and their derivatives,... 相似文献
106.
107.
108.
Siberian Mathematical Journal - Under study are the right-symmetric algebras over a field $ F $ which possess a “unital” matrix subalgebra $... 相似文献
109.
Vanessa R. Machado Louis P. Sandjo Giovanni L. Pinheiro Milene H. Moraes Mario Steindel Moacir G. Pizzolatti 《Natural product research》2018,32(3):275-281
The natural product lupeol 1 was isolated from aerial parts of Vernonia scorpioides with satisfactory yield, which made it viable to be used as starting material in semisynthetic approach. Ten lupeol derivatives 2–11 were prepared by classical procedures. Including, five new esters derivatives 7–11, which were obtained by structural modifications in the isopropylidene fragment. All semisynthetic compounds and lupeol 1–11 were confirmed by 1H NMR, 13C NMR and HRMS. Their antiprotozoal activity was evaluated in vitro against L. amazonensis and T. cruzi. Derivative 6 showed the best antitrypanosomal activity (IC50 = 12.48 μg/mL) and the lowest cytotoxic derivative (CC50 = 161.50 μg/mL). The mechanism of action of the most active derivatives (4, 6 and 11) is not dependent from the enzyme trypanothione reductase. 相似文献
110.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献