全文获取类型
收费全文 | 4340篇 |
免费 | 302篇 |
国内免费 | 143篇 |
专业分类
化学 | 2907篇 |
晶体学 | 44篇 |
力学 | 125篇 |
综合类 | 12篇 |
数学 | 678篇 |
物理学 | 1019篇 |
出版年
2023年 | 77篇 |
2022年 | 75篇 |
2021年 | 97篇 |
2020年 | 159篇 |
2019年 | 132篇 |
2018年 | 66篇 |
2017年 | 95篇 |
2016年 | 184篇 |
2015年 | 134篇 |
2014年 | 165篇 |
2013年 | 208篇 |
2012年 | 281篇 |
2011年 | 300篇 |
2010年 | 164篇 |
2009年 | 142篇 |
2008年 | 222篇 |
2007年 | 216篇 |
2006年 | 191篇 |
2005年 | 176篇 |
2004年 | 127篇 |
2003年 | 107篇 |
2002年 | 114篇 |
2001年 | 69篇 |
2000年 | 70篇 |
1999年 | 51篇 |
1998年 | 38篇 |
1997年 | 48篇 |
1996年 | 53篇 |
1995年 | 40篇 |
1994年 | 38篇 |
1993年 | 32篇 |
1992年 | 38篇 |
1991年 | 24篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 18篇 |
1987年 | 22篇 |
1986年 | 33篇 |
1985年 | 30篇 |
1983年 | 24篇 |
1982年 | 28篇 |
1981年 | 23篇 |
1980年 | 25篇 |
1979年 | 27篇 |
1978年 | 18篇 |
1977年 | 36篇 |
1976年 | 23篇 |
1975年 | 27篇 |
1934年 | 16篇 |
1933年 | 14篇 |
排序方式: 共有4785条查询结果,搜索用时 15 毫秒
1.
Danilov Felix I. Bogdanov Dmytro A. Smyrnova Olena V. Korniy Sergiy A. Protsenko Vyacheslav S. 《Journal of Solid State Electrochemistry》2022,26(4):939-957
Journal of Solid State Electrochemistry - The electrochemical deposition of a nickel–iron alloy from a plating solution based on a deep eutectic solvent (a eutectic mixture of ethylene glycol... 相似文献
2.
Herein, we report an addition to the toolbox for the monitoring and quantification of the hydrolytic decay of pentose-1-phosphates, which are known to be elusive and difficult to quantify. This communication describes how apparent equilibrium shifts of a nucleoside phosphorolysis reaction can be employed to calculate hydrolytic loss of pentose-1-phosphates based on the measurement of post-hydrolysis equilibrium concentrations of a nucleoside and a nucleobase. To demonstrate this approach, we assessed the stability of the relatively stable ribose-1-phosphate at 98 °C and found half-lives of 1.8–11.7 h depending on the medium pH. This approach can be extended to other sugar phosphates and related reaction systems to quantify the stability of UV-inactive and hard-to-detect reaction products and intermediates. 相似文献
3.
4.
5.
Pan Huang Dawen Xu Robert M. Reich Felix Kaiser Boping Liu Fritz E. Kühn 《Tetrahedron letters》2019,60(24):1574-1577
A first example of an Et2Zn mediated silylation of 1-aklynes is reported. A series of functional groups are tolerated in this reaction. Mechanistic studies support Zn alkynilides as intermediates in the reaction. This reaction protocol provides a practical method for the preparation of alkynylsilanes and expands the application of organometallic zinc in organic synthesis. 相似文献
6.
用分子动力学方法对5%负失配条件下面心立方晶体铝薄膜的原子沉积外延生长进行了三维模拟.铝原子间的相互作用采用嵌入原子法(EAM)多体势计算.模拟结果再现了失配位错的形成现象.分析表明,失配位错在形成之初即呈现为Shockley扩展位错,即由两个伯格斯矢量为〈211〉/6的部分位错和其间的堆垛层错组成,两个部分位错的间距、即层错宽度为1.8 nm,与理论计算结果一致;外延晶体薄膜沉积生长中,位错对会发生滑移,但其间距保持稳定.进一步观察发现,该扩展位错产生于一种类似于“局部熔融-重结晶”的表层局部无序紊乱-
关键词:
失配位错
外延生长
薄膜
分子动力学
铝 相似文献
7.
8.
Felix Klein 《Mathematische Annalen》1870,2(2):198-226
Ohne Zusammenfassung 相似文献
9.
In this article we use classical formulas involving the K–Bessel function in two variables to express the Poisson kernel on a Riemannian manifold in terms of the heat kernel. We then use the small time asymptotics of the heat kernel on certain Riemannian manifolds to obtain a meromorphic continuation of the associated Poisson kernel to all values of complex time with identifiable singularities. This result reproves in a different setting by different means a well–known theorem due to Duistermaat and Guillemin [DG 75]. Also, we develop analytic expressions for the heat kernel beyond asymptotic expansions. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
M. Ferro-Luzzi Z.-L. Zhou J.F.J. van den Brand H.J. Bulten J. Lang H.R. Poolman 《Hyperfine Interactions》1997,110(3-4):239-257
We present data showing hyperfine transitions in an atomic deuterium beam induced by the (476 MHz) radio-frequency field of
a 704 MeV electron beam in a storage ring. A polarized deuterium beam, produced in an atomic beam source, was crossed with
a stored electron beam and analyzed with a Breit--Rabi polarimeter. Electron-beam induced transitions were singled out by
injecting different combinations of hyperfine states. Transition probabilities as high as 70% were measured at large currents
(~ 100 mA). All possible deuterium transitions for a radio-frequency of 476 MHz were observed. In addition, a 1--6 transition
resulting from the first harmonic (952 MHz) was observed.
The effects of these transitions are of general importance for the polarized internal target technique applied in nuclear
and particle physics experiments. The data are reasonably described by numerical estimates. The observed mechanism can be
exploited to create nuclear polarized atoms when injecting electron polarized atoms with no net nuclear polarization into
a storage cell. However, when nuclear polarized atoms are injected, care should be taken to avoid this mechanism, since it
would result in depolarization of the atoms. The studies enabled us to choose the magnetic guide field during our spin-dependent
electron--deuteron scattering experiments, such that electron-beam induced depolarizing effects were avoided.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献