全文获取类型
收费全文 | 205126篇 |
免费 | 2329篇 |
国内免费 | 616篇 |
专业分类
化学 | 113842篇 |
晶体学 | 3327篇 |
力学 | 8019篇 |
综合类 | 4篇 |
数学 | 19876篇 |
物理学 | 63003篇 |
出版年
2016年 | 2563篇 |
2015年 | 1964篇 |
2014年 | 2657篇 |
2013年 | 8304篇 |
2012年 | 5745篇 |
2011年 | 7223篇 |
2010年 | 4687篇 |
2009年 | 4603篇 |
2008年 | 6522篇 |
2007年 | 6675篇 |
2006年 | 6412篇 |
2005年 | 5809篇 |
2004年 | 5245篇 |
2003年 | 4706篇 |
2002年 | 4558篇 |
2001年 | 5986篇 |
2000年 | 4570篇 |
1999年 | 3644篇 |
1998年 | 2855篇 |
1997年 | 2893篇 |
1996年 | 2852篇 |
1995年 | 2642篇 |
1994年 | 2516篇 |
1993年 | 2426篇 |
1992年 | 2916篇 |
1991年 | 2775篇 |
1990年 | 2701篇 |
1989年 | 2724篇 |
1988年 | 2646篇 |
1987年 | 2669篇 |
1986年 | 2501篇 |
1985年 | 3364篇 |
1984年 | 3405篇 |
1983年 | 2815篇 |
1982年 | 3008篇 |
1981年 | 2953篇 |
1980年 | 2853篇 |
1979年 | 2984篇 |
1978年 | 3239篇 |
1977年 | 3063篇 |
1976年 | 2974篇 |
1975年 | 2833篇 |
1974年 | 2776篇 |
1973年 | 2786篇 |
1972年 | 1789篇 |
1971年 | 1491篇 |
1968年 | 1955篇 |
1967年 | 2170篇 |
1966年 | 1942篇 |
1965年 | 1531篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle... 相似文献
2.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
3.
Synthesis of Highly Substituted γ‐Butyrolactones by a Gold‐Catalyzed Cascade Reaction of Benzyl Esters 下载免费PDF全文
Maria Camila Blanco Jaimes Alexander Ahrens Daniel Pflästerer Dr. Matthias Rudolph Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):427-433
Easily accessible benzylic esters of 3‐butynoic acids in a gold‐catalyzed cyclization/rearrangement cascade reaction provided 3‐propargyl γ‐butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new C?C bond is an intermolecular process. Initially propargylic–benzylic esters were used, but alkyl‐substituted benzylic esters worked equally well. In the case of the propargylic–benzylic products, a simple treatment of the products with aluminum oxide initiated a twofold tautomerization to the allenyl‐substituted γ‐butyrolactones with conjugation of the carbonyl group, the olefin, and the allene. The synthetic sequence can be conducted stepwise or as a one‐pot cascade reaction with similar yields. Even in the presence of the gold catalyst the new allene remains intact. 相似文献
4.
5.
6.
Synthesis of Small‐Sized,Porous, and Low‐Toxic Magnetite Nanoparticles by Thin POSS Silica Coating 下载免费PDF全文
Dr. Swee Kuan Yen D. Prathyusha Varma Wei Mei Guo Dr. Vincent H. B. Ho Dr. Vimalan Vijayaragavan Dr. Parasuraman Padmanabhan Prof. Kishore Bhakoo Prof. Subramanian Tamil Selvan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):3914-3918
In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging. 相似文献
7.
8.
9.
10.