全文获取类型
收费全文 | 673篇 |
免费 | 24篇 |
国内免费 | 5篇 |
专业分类
化学 | 536篇 |
晶体学 | 5篇 |
力学 | 10篇 |
数学 | 64篇 |
物理学 | 87篇 |
出版年
2022年 | 9篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 18篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 34篇 |
2012年 | 52篇 |
2011年 | 51篇 |
2010年 | 28篇 |
2009年 | 18篇 |
2008年 | 36篇 |
2007年 | 41篇 |
2006年 | 43篇 |
2005年 | 27篇 |
2004年 | 37篇 |
2003年 | 28篇 |
2002年 | 33篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1988年 | 3篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1967年 | 2篇 |
1944年 | 2篇 |
1935年 | 2篇 |
1919年 | 2篇 |
1909年 | 2篇 |
1901年 | 3篇 |
排序方式: 共有702条查询结果,搜索用时 15 毫秒
81.
The reduction of methionine sulfoxide residues in peptides was found to be quantitative by treatment with a low concentration of HF in dimethylsulfide (HF:dimethylsulfide, 1:3, v/v). The reduction was dependent on the acidity function of HF and was optimal with an HF concentration between 25% and 40%. The low HF concentration cleavage reagent also deprotected most of the benzyl alcohol-derived protecting groups. 相似文献
82.
A new approach to the determination of afiatoxins B1, B2, G1 and G2 is given; the method involves high-performance liquid chromatography with amperometric detection in the differential-pulse mode at the dropping mercury electrode with 1-s drop time. These aflatoxins can be determined simultaneously with good resolution but with some compromise in sensitivity. The detection limit of underivatized aflatoxin standards is around 5 ng. Average recoveries of aflatoxins from peanut butter by the Beebe method were G2 81%, G1 87%, B2 77% and B1 76%. 相似文献
83.
We present a small $
\ddot x + (\delta + \epsilon \cos t + \epsilon \cos \omega t) x=0
$
\ddot x + (\delta + \epsilon \cos t + \epsilon \cos \omega t) x=0
相似文献
84.
85.
86.
87.
Tage Christensen Bo Jakobsen Jon Papini Tina Hecksher Jeppe C. Dyre Niels Boye Olsen 《Journal of Non》2011,357(2):346-350
In order to describe relaxation the thermodynamic coefficient can be generalized into a complex frequency-dependent cross response function. We explore theoretically the possibility of measuring for a supercooled liquid near the glass transition. This is done by placing a thermistor in the middle of the liquid which itself is contained in a spherical piezoelectric shell. The piezoelectric voltage response to a thermal power generated in the thermistor is found to be proportional to but factors pertaining to heat diffusion and adiabatic compressibility κS(ω) do also intervene. We estimate a measurable piezoelectric voltage of 1 mV to be generated at 1 Hz for a heating power of 0.3 mW. Together with κS(ω) and the longitudinal specific heat cl(ω) which may also be found in the same setup a complete triple of thermoviscoelastic response functions may be determined when supplemented with shear modulus data. 相似文献
88.
Shumate WJ Mattern DL Jaiswal A Dixon DA White TR Burgess J Honciuc A Metzger RM 《The journal of physical chemistry. B》2006,110(23):11146-11159
We report spectroscopic characterization and unimolecular rectification (asymmetric electrical conduction) measurements of three donor-sigma-acceptor (D-sigma-A) compounds N-(10-nonadecyl)-N-(1-pyrenylmethyl)perylene-3,4,9,10-bis(dicarboximide) (1), N-(10-nonadecyl)-N-(4-[1-pyrenyl]butyl)perylene-3,4,9,10-bis(dicarboximide) (2), and N-(10-nonadecyl)-N-(2-ferrocenylethyl)perylene-3,4,9,10-bis(dicarboximide) (3). These molecules were arranged as one-molecule thick Langmuir-Blodgett monolayers between Au electrodes. In such an "Au | D-sigma-A | Au" sandwich, molecule 1 is a unimolecular rectifier, with rather small rectification ratios (between 2 and 3 at +/-1 V) that decrease upon cycling. Molecule 2 does not rectify. Molecule 3 rectifies, with a rectification ratio of between 14 and 28 at +/-1 V; the through-film rectification and currents persist, even with scans of +/-2 V, for up to 40 cycles of measurement. Qualitative arguments, based on a two-level rectification mechanism, are consistent with the current asymmetries observed in the monolayers of 1 and 3. 相似文献
89.
Biocatalytic deuterium- and hydrogen-transfer using over-expressed ADH-'A': enhanced stereoselectivity and 2H-labeled chiral alcohols 总被引:1,自引:0,他引:1
Edegger K Gruber CC Poessl TM Wallner SR Lavandera I Faber K Niehaus F Eck J Oehrlein R Hafner A Kroutil W 《Chemical communications (Cambridge, England)》2006,(22):2402-2404
Employing the over-expressed highly organic solvent tolerant alcohol dehydrogenase ADH-'A' from Rhodococcus ruber DSM 44541, versatile building blocks, which were not accessible by the wild type catalyst, were obtained in > 99% e.e.; furthermore, employing d8-2-propanol as deuterium source, stereoselective biocatalytic deuterium transfer was made feasible to furnish enantiopure deuterium labeled sec-alcohols on a preparative scale employing a single enzyme. 相似文献
90.
Marc‐Andr Kasper Andreas Stengl Philipp Ochtrop Marcus Gerlach Tina Stoschek Dominik Schumacher Jonas Helma Martin Penkert Eberhard Krause Heinrich Leonhardt Christian P. R. Hackenberger 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11757-11762
Requirements for novel bioconjugation reactions for the synthesis of antibody–drug conjugates (ADCs) are exceptionally high, since conjugation selectivity as well as the stability and hydrophobicity of linkers and payloads drastically influence the performance and safety profile of the final product. We report Cys‐selective ethynylphosphonamidates as new reagents for the rapid generation of efficacious ADCs from native non‐engineered monoclonal antibodies through a simple one‐pot reduction and alkylation. Ethynylphosphonamidates can be easily substituted with hydrophilic residues, giving rise to electrophilic labeling reagents with tunable solubility properties. We demonstrate that ethynylphosphonamidate‐linked ADCs have excellent properties for next‐generation antibody therapeutics in terms of serum stability and in vivo antitumor activity. 相似文献