全文获取类型
收费全文 | 280篇 |
免费 | 5篇 |
专业分类
化学 | 212篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 42篇 |
物理学 | 26篇 |
出版年
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 8篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1989年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 7篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1895年 | 1篇 |
排序方式: 共有285条查询结果,搜索用时 31 毫秒
61.
Halina D. Inerowicz 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(3-4):211-214
Novel chromogenic crown ethers having an intraannular azo and phenolic hydroxy subunits have been used as complexing reagents for alkali metal cations. The complex formation was studied by visible spectroscopy and formation constants were calculated. The most pronounced spectral changes were observed for lithium ion. 相似文献
62.
Dr. Hanna Jędrzejewska Dr. Ewelina Wielgus Dr. Sławomir Kaźmierski Halina Rogala Dr. Michał Wierzbicki Dr. Aneta Wróblewska Dr. Tomasz Pawlak Prof. Marek J. Potrzebowski Prof. Agnieszka Szumna 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1558-1566
Mechanical grinding/milling can be regarded as historically the first technology for changing the properties of matter. Mechanically activated molecular units (mechanophores) can be present in various structures: polymers, macromolecules, or small molecules. However, only polymers have been reported to effectively transduce energy to mechanophores, which induces breakage of covalent bonds. In this paper, a second possibility is presented—molecular capsules as stress-sensitive units. Mechanochemical encapsulation of fullerenes in cystine-based covalent capsules indicates that complexation takes place in the solid state, despite the fact that the capsules do not possess large enough entrance portals. By using a set of solvent-free MALDI (sf-MALDI) and solid-state NMR (ss-NMR) experiments, it has been proven that encapsulation proceeds during milling and in this process hydrazones and disulfides get activated for breakage, exchange, and re-forming. The capsules are porous and therefore prone to collapse under solvent-free conditions and their conformational rigidity promotes the collapse by the breaking of covalent bonds. 相似文献
63.
Marek Chmielewski Zbigniew KaŁuża Czesław Bełżecki Piotr SaŁanski Janusz Jurczak Halina Adamowicz 《Tetrahedron》1985,41(12):2441-2449
High-pressure (2+2)cycloaddition of toluene-4-sulphonyl isocyanate to glycals is examined. Reactions proceed regiospecifically to afford single products in case of all 3-substituted glycals. Upon heating or even after standing at room temperature adducts undergo retro-addition to give starting glycals. Various aspects of the cycloaddition are discussed, especially ret-ro-reaction and rearrangement of β-lactams to α,β-unsaturated amides. 相似文献
64.
Iga Zuba Halina Polkowska-Motrenko 《Journal of Radioanalytical and Nuclear Chemistry》2018,318(2):967-972
A radiochemical neutron activation analysis procedure was developed for the determination of trace amounts of gold in biological materials. The procedure was realized with irradiation of reference and test samples in a nuclear reactor, selective and quantitative separation of gold using inorganic MnO2 Resin and gamma-ray spectrometric measurement of 198Au. The method is characterized by a low limit of detection of gold at ng g?1 level. Results shows that the method can be applied to the determination of trace amounts of gold in tissues for medical research. 相似文献
65.
66.
We measure the point-spread function in the two main configurations of 4Pi confocal microscopy as well as in the traditional confocal arrangement and derive the optical transfer functions from the experimental data. The optical transfer functions are in good agreement with their theoretical counterparts. We find a 3.5- to 5-fold increased axial bandwidth of the 4Pi confocal microscope and hence confirm the enhanced spatial-frequency content of 4Pi images. 相似文献
67.
Warner JH Watt AR Thomsen E Heckenberg N Meredith P Rubinsztein-Dunlop H 《The journal of physical chemistry. B》2005,109(18):9001-9005
Steady-state and time-resolved photoluminescence spectroscopy are used to examine the photoluminescent properties of nanocrystal-polymer composites consisting of colloidal PbS nanocrystals blended with poly(2-methoxy-5(2-ethylhexyloxy)-p-phenylene vinylene). Quenching of the emission from the conjugated polymer due to the PbS nanocrystals is observed along with band edge emission from the ligand capped PbS nanocrystals. A decrease in the photoluminescence lifetime of MEH-PPV is also observed in the thin film nanocrystal-polymer composite materials. Photoluminescence excitation spectroscopy of the PbS nanocrystal emission from the composite shows features attributed to MEH-PPV providing evidence of a F?rster transfer process. 相似文献
68.
69.
Structural Chemistry - Stacking interactions play an important role in stabilizing DNA and RNA secondary structure. To select a computational level to study the stacking interactions, both energy... 相似文献
70.
JPC – Journal of Planar Chromatography – Modern TLC - Carbohydrates have been examined by TLC on layers modified with metal ions, in the form of salts, by dipping commercial plates in... 相似文献