全文获取类型
收费全文 | 32411篇 |
免费 | 229篇 |
国内免费 | 296篇 |
专业分类
化学 | 12640篇 |
晶体学 | 267篇 |
力学 | 1457篇 |
综合类 | 12篇 |
数学 | 9630篇 |
物理学 | 8930篇 |
出版年
2021年 | 91篇 |
2020年 | 141篇 |
2019年 | 114篇 |
2018年 | 1213篇 |
2017年 | 1499篇 |
2016年 | 820篇 |
2015年 | 633篇 |
2014年 | 554篇 |
2013年 | 757篇 |
2012年 | 3283篇 |
2011年 | 2473篇 |
2010年 | 1885篇 |
2009年 | 1593篇 |
2008年 | 694篇 |
2007年 | 713篇 |
2006年 | 716篇 |
2005年 | 4530篇 |
2004年 | 3994篇 |
2003年 | 2365篇 |
2002年 | 560篇 |
2001年 | 347篇 |
2000年 | 148篇 |
1999年 | 208篇 |
1998年 | 143篇 |
1997年 | 103篇 |
1996年 | 79篇 |
1995年 | 75篇 |
1994年 | 83篇 |
1993年 | 67篇 |
1992年 | 219篇 |
1991年 | 195篇 |
1990年 | 182篇 |
1989年 | 159篇 |
1988年 | 138篇 |
1987年 | 92篇 |
1986年 | 94篇 |
1985年 | 93篇 |
1984年 | 72篇 |
1983年 | 67篇 |
1982年 | 63篇 |
1979年 | 74篇 |
1978年 | 69篇 |
1977年 | 70篇 |
1976年 | 119篇 |
1975年 | 77篇 |
1974年 | 79篇 |
1973年 | 89篇 |
1972年 | 71篇 |
1970年 | 67篇 |
1967年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 31 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.
Julia K Pruns Jens-Peter Vietzke Manfred Strassner Claudius Rapp Ulrich Hintze Wilfried A K?nig 《Rapid communications in mass spectrometry : RCM》2002,16(3):208-211
A new solvent-free sample preparation method using silver trifluoroacetate (AgTFA) was developed for the analysis of low molecular weight paraffins and microcrystalline waxes by laser desorption/ionization time-of-flight mass spectrometry (LDI-TOFMS). Experiments show that spectral quality can be enhanced by dispersing AgTFA directly in liquid paraffins without the use of additional solvents. This preparation mixture is applied directly to the MALDI probe. Solid waxes could be examined by melting prior to analysis. The method also provides sufficiently reproducible spectra that peak area ratios between mono- and bicyclic alkane peaks indicated variations in the cycloalkane content of paraffin samples. Dehydrogenation of hydrocarbons observed during the desorption/ionization process was studied by analysis of alkane standards. 相似文献
7.
The versatile behavior of a trihydrazidophosphoradamantane allowing the synthesis of a variety of neutral, mono- or di-cationic water-soluble molecules of potential interest for biphasic catalysis is reported. 相似文献
8.
In this paper we construct an example of a word metric on an infinite cyclic subgroup. This example shows that subexponential
distortion does not obstruct non-trivial growth of connected radii. This answers a question of Gromov [6]. The constructed
metric has other pathological properies. Specifically, its asymptotic cone depends on the choice of ultrafilter and scaling
sequence.
The work has been partially supported by the Swiss National Science Foundation. 相似文献
9.
We build a metric space which is homeomorphic to a Cantor set but cannot be realized as the attractor of an iterated function system. We give also an example of a Cantor set K in R3 such that every homeomorphism f of R3 which preserves K coincides with the identity on K. 相似文献
10.
Milan Medved? 《Journal of Mathematical Analysis and Applications》2002,267(2):643-650
A criterion for the nonexplosion of solutions to semilinear evolution equations on Banach spaces is proved. The result is obtained by applying a modification of the Bihari type inequality to the case of a weakly singular nonlinear integral inequality. 相似文献