全文获取类型
收费全文 | 1079篇 |
免费 | 55篇 |
国内免费 | 10篇 |
专业分类
化学 | 771篇 |
晶体学 | 23篇 |
力学 | 9篇 |
数学 | 105篇 |
物理学 | 236篇 |
出版年
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 23篇 |
2020年 | 23篇 |
2019年 | 33篇 |
2018年 | 18篇 |
2017年 | 11篇 |
2016年 | 36篇 |
2015年 | 24篇 |
2014年 | 31篇 |
2013年 | 63篇 |
2012年 | 83篇 |
2011年 | 87篇 |
2010年 | 56篇 |
2009年 | 47篇 |
2008年 | 52篇 |
2007年 | 66篇 |
2006年 | 58篇 |
2005年 | 48篇 |
2004年 | 40篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 18篇 |
2000年 | 24篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 10篇 |
1972年 | 8篇 |
1970年 | 7篇 |
1969年 | 4篇 |
排序方式: 共有1144条查询结果,搜索用时 15 毫秒
61.
62.
Symmetrically functionalized pyrazine of 3,6‐dibromopyrazine‐2,5‐dicarbonitrile was synthesized in three or four steps from 3‐aminopyrazinecarbonitrile or its 6‐bromo derivatives. 相似文献
63.
Dr. Yinhua Huang Guo Hao Chan Prof. Shunsuke Chiba 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6644-6647
A new protocol for amide-directed ortho and lateral C−H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds. 相似文献
64.
Back Cover: Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite (Chem. Eur. J. 21/2016)
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)
65.
Ozawa M 《Physical review letters》2002,89(5):057902
The Wigner-Araki-Yanase theorem shows that conservation laws limit the accuracy of measurement. Here, we generalize the argument to show that conservation laws limit the accuracy of quantum logic operations. A rigorous lower bound is obtained of the error probability of any physical realization of the controlled-NOT gate under the constraint that the computational basis is represented by a component of spin, and that physical implementations obey the angular momentum conservation law. The lower bound is shown to be inversely proportional to the number of ancilla qubits or the strength of the external control field. 相似文献
66.
Ozawa M 《Physical review letters》2002,88(5):050402
The uncertainty relation between the noise operator and the conserved quantity leads to a bound on the accuracy of general measurements. The bound extends the assertion by Wigner, Araki, and Yanase that conservation laws limit the accuracy of "repeatable," or "nondisturbing," measurements to general measurements, and improves the one previously obtained by Yanase for spin measurements. The bound represents an obstacle to making a small quantum computer. 相似文献
67.
High-speed recovery of germanium in a convection-aided mode using functional porous hollow-fiber membranes 总被引:1,自引:0,他引:1
A porous hollow-fiber membrane capable of recovery of germanium from a liquid stream was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate, and subsequent functionalization with 2,2'-iminodiethanol, di-2-propanolamine, N-methylglucamine, and 3-amino-1,2-propanediol. The functional group density was as high as 1.4 mol per kg of the resultant hollow fiber. The polymer chains containing functional groups surrounding the pores enabled a high-speed recovery of germanium during permeation of a germanium oxide (GeO2) solution through the pores of the hollow fiber. Because of a negligible diffusional mass-transfer resistance, germanium concentration changes with the effluent volume, i.e., breakthrough curves, overlapped irrespective of the residence time of the solution, which ranged from 0.37 to 3.7 s across the hollow fiber. After repeated use of adsorption and elution, the adsorption capacity did not deteriorate. 相似文献
68.
69.
70.
We demonstrate the efficiency of the optical poling process that depends on the CE phase-controlled quantum interference. For the experiment we employed our noncollinear optical parametric amplifier system for the self-stabilization of the CE phase, with the f-to-2f spectral interferometry system to control the CE phase. 相似文献