全文获取类型
收费全文 | 5497篇 |
免费 | 252篇 |
国内免费 | 9篇 |
专业分类
化学 | 3599篇 |
晶体学 | 27篇 |
力学 | 109篇 |
数学 | 1080篇 |
物理学 | 943篇 |
出版年
2023年 | 44篇 |
2022年 | 49篇 |
2021年 | 76篇 |
2020年 | 99篇 |
2019年 | 109篇 |
2018年 | 120篇 |
2017年 | 97篇 |
2016年 | 165篇 |
2015年 | 176篇 |
2014年 | 196篇 |
2013年 | 371篇 |
2012年 | 415篇 |
2011年 | 449篇 |
2010年 | 244篇 |
2009年 | 210篇 |
2008年 | 355篇 |
2007年 | 332篇 |
2006年 | 278篇 |
2005年 | 277篇 |
2004年 | 235篇 |
2003年 | 181篇 |
2002年 | 169篇 |
2001年 | 63篇 |
2000年 | 54篇 |
1999年 | 50篇 |
1998年 | 42篇 |
1997年 | 38篇 |
1996年 | 45篇 |
1995年 | 34篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 27篇 |
1990年 | 27篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 25篇 |
1985年 | 39篇 |
1984年 | 41篇 |
1983年 | 22篇 |
1982年 | 36篇 |
1981年 | 32篇 |
1980年 | 44篇 |
1979年 | 34篇 |
1978年 | 36篇 |
1977年 | 36篇 |
1976年 | 35篇 |
1975年 | 31篇 |
1974年 | 19篇 |
1973年 | 20篇 |
排序方式: 共有5758条查询结果,搜索用时 359 毫秒
1.
Peralta Cecilia Mariana Acosta Gimena Henestrosa Cecilia Gil Raúl Andrés Fernández Liliana Patricia 《Journal of Analytical Chemistry》2022,77(3):308-317
Journal of Analytical Chemistry - The present development involved a flow injection strategy using a mini-column of multiwalled carbon nanotubes and fluorescent detection (λex of 283 nm,... 相似文献
2.
Mathieu Boiret Anna de Juan Nathalie Gorretta Yves-Michel Ginot Jean-Michel Roger 《Analytica chimica acta》2015
Raman chemical imaging provides chemical and spatial information about pharmaceutical drug product. By using resolution methods on acquired spectra, the objective is to calculate pure spectra and distribution maps of image compounds. With multivariate curve resolution-alternating least squares, constraints are used to improve the performance of the resolution and to decrease the ambiguity linked to the final solution. Non negativity and spatial local rank constraints have been identified as the most powerful constraints to be used. 相似文献
3.
Lithium Insertion Mechanism in Iron-Based Oxyfluorides with Anionic Vacancies Probed by PDF Analysis
Dr. Damien Dambournet Dr. Karena W Chapman Dr. Mathieu Duttine Dr. Olaf Borkiewicz Dr. Peter J Chupas Dr. Henri Groult 《ChemistryOpen》2015,4(4):443-447
The mechanism of lithium insertion that occurs in an iron oxyfluoride sample with a hexagonal–tungsten–bronze (HTB)-type structure was investigated by the pair distribution function. This study reveals that upon lithiation, the HTB framework collapses to yield disordered rutile and rock salt phases followed by a conversion reaction of the fluoride phase toward lithium fluoride and nanometer-sized metallic iron. The occurrence of anionic vacancies in the pristine framework was shown to strongly impact the electrochemical activity, that is, the reversible capacity scales with the content of anionic vacancies. Similar to FeOF-type electrodes, upon de-lithiation, a disordered rutile phase forms, showing that the anionic chemistry dictates the atomic arrangement of the re-oxidized phase. Finally, it was shown that the nanoscaling and structural rearrangement induced by the conversion reaction allow the in situ formation of new electrode materials with enhanced electrochemical properties. 相似文献
4.
5.
András Gy. Németh Renáta Szabó Dr. Attila Domján Prof. György M. Keserű Dr. Péter Ábrányi-Balogh 《ChemistryOpen》2021,10(1):16-27
The development of a new three-component chromatography-free reaction of isocyanides, amines and elemental sulfur allowed us the straightforward synthesis of thioureas in water. Considering a large pool of organic and inorganic bases, we first optimized the preparation of aqueous polysulfide solution from elemental sulfur. Using polysulfide solution, we were able to omit the otherwise mandatory chromatography, and to isolate the crystalline products directly from the reaction mixture by a simple filtration, retaining the sulfur in the solution phase. A wide range of thioureas synthesized in this way confirmed the reasonable substrate and functional group tolerance of our protocol. 相似文献
6.
7.
Thermodynamic study of transthyretin association (wild‐type and senile forms) with heparan sulfate proteoglycan: pH effect and implication of the reactive histidine residue
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ambre Geneste Claire André Nadine Magy‐Bertrand Lydie Lethier Gharbi Tijani Yves Claude Guillaume 《Biomedical chromatography : BMC》2015,29(4):514-522
The tetramer destabilization of transthyretin into monomers and its fibrillation are phenomena leading to amyloid deposition. Heparan sulfate proteoglycan (HSPG) has been found in all amyloid deposits. A chromatographic approach was developed to compare binding parameters between wild‐type transthyretin (wtTTR) and an amyloidogenic transthyretin (sTTR). Results showed a greater affinity of sTTR for HSPG at pH 7.4 compared with wtTTR owing to the monomeric form of sTTR. Analysis of the thermodynamic parameters showed that van der Waals interactions were involved at the complex interface for both transthyretin forms. For sTTR, results from the plot representing the number of protons exchanged vs pH showed that the binding mechanism was pH‐dependent with a critical value at a pH 6.5. This observation was due to the protonation of a histidine residue as an imidazolium cation, which was not accessible when TTR was in its tetrameric structure. At pH >6.5, dehydration at the binding interface and several contacts between nonpolar groups of sTTR and HSPG were also coupled to binding for an optimal hydrogen‐bond network. At pH <6.5, the protonation of the His residue from sTTR monomer when pH decreased broke the hydrogen‐bond network, leading to its destabilization and thus producing slight conformational changes in the sTTR monomer structure. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
9.
Andr Voet 《Colloid and polymer science》1937,78(2):201-204
Zusammenfassung Es wird eine Methode angegeben, welche auf Grund von Flockungsversuchen lyophober Sole die numerische Festlegung der lyotropen
Reihe erm?glicht.
Vorl?ufige Mitteilung: Büchner, Voet und Bruins, Proc. Acad. Sci. Amsterdam35, 563 (1932). 相似文献
10.
André Markoff 《Mathematische Annalen》1886,27(2):177-182
Sans résumé 相似文献