全文获取类型
收费全文 | 162篇 |
免费 | 9篇 |
专业分类
化学 | 111篇 |
力学 | 7篇 |
数学 | 42篇 |
物理学 | 11篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1954年 | 1篇 |
1941年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有171条查询结果,搜索用时 15 毫秒
31.
S Ghiassian H Ismaili BD Lubbock JW Dube PJ Ragogna MS Workentin 《Langmuir : the ACS journal of surfaces and colloids》2012,28(33):12326-12333
3-Aryl-3-(trifluormethyl)diazirine functionalized highly fluorinated phosphonium salts (HFPS) were synthesized, characterized, and utilized as photoinduced carbene precursors for covalent attachment of the HFPS onto cotton/paper to impart hydrophobicity to these surfaces. Irradiation of cotton and paper, as proof of concept substrates, treated with the diazirine-HFPS leads to robust hydrophobic cotton and paper surfaces with antiwetting properties, whereas the corresponding control samples absorb water readily. The contact angles of water were determined to be 139° and 137° for cotton and paper, respectively. In contrast, water placed on the untreated or the control samples (those treated with the diazirine-HFPS but not irradiated) is simply absorbed into the surface. Additionaly, the chemically grafted hydrophobic coating showed high durability toward wash cycles and sonication in organic solvents. Because of the mode of activation to covalently tether the hydrophobic coating, it is amenable to photopatterning, which was demonstrated macroscopically. 相似文献
32.
Using the basic hydrodynamic equations governing motion in the sea, a coastal zone numerical model has been developed for the prediction of storm surges along the west coast of India. Numerical experiments were performed with the help of this model to simulate the surge generated by the devastating 1975 Porbandar cyclone. The results of the experiments were in good agreement with the reported values along the Gujarat coast. 相似文献
33.
34.
M.P. Dube R. Rasoanaivo Y. Hahn 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,33(1):13-26
The dielectronic recombination (DR) rate coefficient αDR is explicitly calculated for the Si, Ar, Fe and Mo target ions of the Mg isoelectronic sequence with twelve electrons. Both the 3s, Δn ≠ 0 and 3s, Δn = 0 transitions are considered in detail. An explicit LS coupling scheme was applied to all the dominant transitions of these ions. Results of αDR with different free electron temperatures are also discussed 相似文献
35.
36.
Ravi Patel Abhishek Dube Ravisinh Solanki Dignesh Khunt Shalin Parikh Vijayabhaskarreddy Junnuthula Sathish Dyawanapelly 《Molecules (Basel, Switzerland)》2022,27(17)
A novel stability-indicating, reversed-phase, high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination of favipiravir in an oral suspension. The effective separation of favipiravir and its degradation products was achieved on a Zorbax Eclipse Plus C18 column (5 μm particle size, 150 mm length × 4.6 mm diameter). The mobile phase was prepared by mixing 5 mM of phosphate buffer (pH 3.5) and methanol in a 75:25 v/v ratio delivered at a 1.0 mL/min flow rate. The eluents were monitored using a photodiode array detector at a wavelength of 322 nm. The stability-indicating nature of this method was evaluated by performing force degradation studies under various stress conditions, such as acidic, alkali, oxidative, thermal, and photolytic degradation. Significant degradation was observed during the alkali stress degradation condition. The degradation products generated during various stress conditions were well separated from the favipiravir peak. In addition, the major degradation product formed under alkali stress conditions was identified using UPLC-ESI-TQ-MS/MS and NMR. Method validation was performed according to the ICH Q2 (R1) guideline requirements. The developed method is simple, accurate, robust, and reliable for routine quality control analysis of favipiravir oral suspensions. 相似文献
37.
Epunctanone,a New Benzophenone,and Further Secondary Metabolites from Garcinia epunctata Stapf (Guttiferae) 下载免费PDF全文
Ghislain W. Fotso Aku N. Ntumy Eliette Ngachussi Mthandazo Dube Renameditswe Mapitse Gilbert D. W. F. Kapche Kerstin Andrae‐Marobela Bonaventure T. Ngadjui Berhanu M. Abegaz 《Helvetica chimica acta》2014,97(7):957-964
A new polyprenylated benzophenone, named epunctanone ( 1 ), was isolated from the stem bark of Garcinia epunctata Stapf , together with eight known compounds, 7‐epiisogarcinol ( 2 ), 2,6‐dimethoxy‐p‐benzoquinone ( 3 ), friedelin ( 4 ), lupeol ( 5 ), 16β‐hydroxylupeol ( 6 ), betulin ( 7 ), stigmasterol ( 8 ), and rheediaxanthone A ( 9 ). The structure of epunctanone ( 1 ) was established by detailed analysis of its spectroscopic data, especially 1D‐ and 2D‐NMR, and HR‐MS data. All these compounds were evaluated for their antimicrobial and anti‐protozoan activities. They were also assayed to determine if any of the compounds were nonpeptide agonist ligands for nematodal G‐protein‐coupled receptors, which would be an indication of potential antinematodal activity. Among the isolated compounds, 7‐epiisogarcinol ( 2 ) was the most active against Candida albicans. 相似文献
38.
Summary The dual separation mechanism exhibited by capillary electrochromatography is demonstrated by the simultaneous separation
of sulfonamides as charged and neutral species over a pH range of 2.5 to 6.9. The neutral sulfonamides were separated according
to the difference in their hydrophobicities while charged components were separated by the differences in their electrophoretic
mobilities. The limitation of capillary electrochromatography for acidic components was also examined. 相似文献
39.
Manuel Guentner Edgar Uhl Dr. Peter Mayer Dr. Henry Dube 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16433-16436
The first example of a bis‐hemithioindigo (bis‐HTI)‐based molecular receptor was realized. Its folding and selective binding affinity for aromatic guest molecules can be precisely controlled by visible light and heat. The thermodynamically stable state of the bis‐HTI is the s‐shaped planar Z,Z‐configuration. After irradiation with 420 nm light only the E,Z‐configuration is formed in a highly selective photoisomerization. The E,Z‐isomer adopts a helical conformation because of the implementation of repulsive steric interactions. The E,Z‐configured helix is able to recognize electron‐poor aromatic guests exclusively through polar aromatic interactions and also distinguishes between regioisomers. After heating, the Z,Z‐configuration is completely restored and the aromatic guest molecule is efficiently released. 相似文献
40.
Davlat Kh. Akramov Nilufar Z. Mamadalieva Andrea Porzel Hidayat Hussain Mthandazo Dube Akbar Akhmedov Ahmed E. Altyar Mohamed L. Ashour Ludger A. Wessjohann 《Molecules (Basel, Switzerland)》2021,26(6)
Phytochemical investigation of the methanolic extract obtained from the aerial parts of Lagochilus setulosus (Lamiaceae) afforded the new compound 1-methoxy-3-O-β-glucopyranosyl-α-l-oliose (1) together with five known glycosides, namely sitosterol-3-O-β-glucoside (2), stigmasterol-3-O-β-glucoside (3), pinitol (4), 6β-hydroxyl-7-epi-loganin (5), and chlorotuberoside (6). The structures of these compounds were elucidated by extensive spectroscopic analyses, especially HR-MS, 1D and 2D NMR spectroscopy. The in vitro cytotoxic activity of the methanolic extract and the isolated compounds was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and crystal violet (CV) staining assays. In addition, the antifungal activities of the components were evaluated against Botrytis cinerea, Septoria tritici, and Phytophthora infestans. The anthelmintic potential was determined against Caenorhabditis elegans nematodes. Neither the extract nor the isolated compounds showed promising activity in all the bioassays. 相似文献