全文获取类型
收费全文 | 1196篇 |
免费 | 52篇 |
国内免费 | 4篇 |
专业分类
化学 | 743篇 |
晶体学 | 5篇 |
力学 | 47篇 |
数学 | 226篇 |
物理学 | 231篇 |
出版年
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 18篇 |
2020年 | 27篇 |
2019年 | 13篇 |
2018年 | 21篇 |
2017年 | 21篇 |
2016年 | 32篇 |
2015年 | 34篇 |
2014年 | 41篇 |
2013年 | 65篇 |
2012年 | 110篇 |
2011年 | 93篇 |
2010年 | 62篇 |
2009年 | 51篇 |
2008年 | 92篇 |
2007年 | 66篇 |
2006年 | 71篇 |
2005年 | 59篇 |
2004年 | 49篇 |
2003年 | 41篇 |
2002年 | 46篇 |
2001年 | 18篇 |
2000年 | 22篇 |
1999年 | 7篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1989年 | 3篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 12篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1947年 | 5篇 |
1938年 | 2篇 |
1931年 | 2篇 |
1886年 | 2篇 |
排序方式: 共有1252条查询结果,搜索用时 15 毫秒
91.
92.
S. Andrieu F. Ferrieu F. Arnaud d'Avitaya 《Applied Physics A: Materials Science & Processing》1989,49(6):719-722
In this paper, we present an analysis of antinomy deposition on silicon in the range of 0.1 to 1 monolayer by in situ spectroscopic ellipsometry. After a careful choice of viewpoint material, ellipsometric measurements are found to be sensitive to small surface perturbations, especially with antimony. In fact, less than a 0.1 monolayer of antimony on silicon at room temperature is detectable. Moreover, a linear dependence of the ellipsometric signal on Sb coverage is observed in the monolayer range. Consequently, the signal versus time variation directly gives the Sb adsorption kinetics on silicon. The saturation to one monolayer of compact antimony on silicon surface is used in order to calibrate the spectra. 相似文献
93.
94.
96.
Regis D. Gougeon Dr. Marianna Lucio Arnaud De Boel Moritz Frommberger Dr. Norbert Hertkorn Dr. Dominique Peyron Dr. David Chassagne Dr. François Feuillat Dr. Philippe Cayot Prof. Andrée Voilley Prof. Istvan Gebefügi Dr. Philippe Schmitt‐Kopplin Priv.‐Doz. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):600-611
A non‐targeted, ultra‐high‐resolution mass spectrometric, direct analysis of oak‐wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra‐high‐resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated by both FTMS and NMR data. For the first time, it is shown that oak woods can also be discriminated on the basis of hundreds of forest‐related compounds, and particular emphasis is put on sessile oaks from the Tronçais forest, for which sugars are significantly discriminant. Despite the higher complexity and diversity of wine metabolites, forest‐related compounds can also be detected in wines aged in related barrels. It is only by using these non‐targeted analyses that such innovative results, which reveal specific chemodiversities of natural materials, can be obtained. 相似文献
97.
A regio- and stereoselective iodination has been performed on vicinal diols located on ketopyranose templates using the controlled- Garegg conditions. 3-O-Benzyl-1,2-O-isopropylidene-β-d-fructo- or psicopyranoses (1 or 4) were selectively iodinated, respectively, at C-5 or C-4 of the ketoses to afford the l-sorbo or d-sorbo iodohydrins. 相似文献
98.
Heterogeneous photocatalysis is a recent discipline particularly well adapted to environmental problems since it operates
at room temperature by replacing catalyst’s thermo-activation by photo-activation (or replacing phonons by photons). In fine
chemistry, high initial selectivities (100%) are obtained in dry organic media in selective mild oxidation of gaseous or liquid
hydrocarbons. Similarly, 100% selectivities were obtained in sulfur-involving photocatalytic reactions, noted as “thio-photocatalysis”.
Environmental photocatalysis is active in water and air decontamination and can advantageously use the UV-A solar spectrum
for outside applications. 相似文献
99.
Mei Wang Nathalie Simon Gaelle Charrier Muriel Bouttemy Arnaud Etcheberry Musen Li Rabah Boukherroub Sabine Szunerits 《Electrochemistry communications》2010,12(3):351-354
While it is clearly established that oxidation of as-grown boron-doped diamond (BDD) interfaces results in the introduction of different surface oxygen functions such as ether, carbonyl and hydroxyl groups, there is no reported approach which can clearly distinguish between the different surface functions. For further surface functionalization, it is important to quantify the presence of each group on the diamond surface. In this paper, the presence and amount of surface hydroxyl groups is identified using esterification of the COH groups with trifluoroacetic acid. The presence of CF3 group in the acid allowed the identification and estimation of the amount of surface hydroxyl groups using X-ray photoelectron spectroscopy (XPS). 相似文献
100.
Jalal Ghilane Pascal Martin Hyacinthe Randriamahazaka Jean-Christophe Lacroix 《Electrochemistry communications》2010,12(2):246-249
Electrochemical oxidation of primary amine in ionic liquid media has been investigated. The ionic liquid chosen for this study was 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Two primary amine compounds are used for this study; 4-nitrobenzylamine and 2-aminoethylferrocenylmethylether. The oxidation of the amino compounds in ionic liquid conduces to the modification of the electrode surface. The modified electrodes were characterized by cyclic voltammetry and XPS analysis. Both techniques support the presence of an organic layer strongly attached onto the electrode surface. The surface concentration of the attached group obtained in this media was found to be around 1 to 3 × 10?10 mol cm?2. The use of ionic liquid as media for the grafting leads to decrease of the surface concentration of the grafted layer; and the formation of less dense layer compared with classical solvent such as acetonitrile. 相似文献