全文获取类型
收费全文 | 424篇 |
免费 | 8篇 |
专业分类
化学 | 343篇 |
晶体学 | 8篇 |
力学 | 11篇 |
数学 | 22篇 |
物理学 | 48篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 36篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 10篇 |
2013年 | 30篇 |
2012年 | 26篇 |
2011年 | 28篇 |
2010年 | 20篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 25篇 |
2006年 | 25篇 |
2005年 | 22篇 |
2004年 | 17篇 |
2003年 | 13篇 |
2002年 | 20篇 |
2001年 | 17篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有432条查询结果,搜索用时 861 毫秒
51.
Piotr Kowalski Jolanta Jaśkowska Andrzej J. Bojarski Beata Duszyńska Adam Bucki Marcin Kołaczkowski 《Journal of heterocyclic chemistry》2011,48(1):192-198
The synthesis and evaluation as 5‐HT1A and 5‐HT7 serotonin receptor ligands of the two sets of O‐substituted hydroxybenzamides, structurally related to 2‐{3‐[4‐(2‐methoxyphenyl)piperazin‐1‐yl]propoxy}benzamide ( 1 ), (Ki 5‐HT1A = 21 nM, 5‐HT7 = 234 nM) are reported. To affect the affinity for 5‐HT1A and 5‐HT7 receptors, an amide moiety ( 2 , 3 , 4 , 5 , 6 ) and a hydrocarbon chain length ( 7 , 8 , 9 , 10 ) were modified. The serotonergic activity of compounds 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 was generally higher in the case of 5‐HT1A receptors compared with 5‐HT7 ones; the most active 5‐HT1A ligands being meta‐isomer 2 (Ki = 7 nM) and both analogs of 1 with the longest spacer, i.e., penta‐ and hexa‐methylene derivatives 9 and 10 (Ki = 4 and 3 nM, respectively). The observed biological properties of compounds 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 were elucidated using molecular modeling procedures. J. Heterocyclic Chem., (2010). 相似文献
52.
Titania layers obtained by a sol-gel technique doped with redox mediator, Meldola’s Blue, were employed for construction of
a new NADH senor. Optimization of preparation process as well as experimental conditions affecting the response of the sensor
were examined. Under optimal conditions NADH could be determined in the wide linear range from 90 to 2300 μM with detection
limit 12 μM and a high sensitivity 12.5 nA μM−1. The usefulness of developed sensor was preliminarily checked in determination of NADH forming during enzymatic oxidation
of ethanol catalyzed by alcohol dehydrogenase (ADH).
相似文献
53.
JPC – Journal of Planar Chromatography – Modern TLC - The lipophilicity of twenty-one N-benzyl-2-azaspiro[4.4]nonaneand [4.5]decane-1,3-dione derivatives, fifteen of which (1–15)... 相似文献
54.
Jolanta Galazka-Friedman 《Hyperfine Interactions》2008,182(1-3):31-44
In this review the properties of iron in various human brain structures (e.g. Substantia nigra, globus pallidus, hippocampus) were analyzed to assess the possibility of initiation of oxidative stress leading to such diseases as Parkinson’s and Alzheimer’s disease, and progressive supranuclear palsy. Our own studies with the use of Mössbauer spectroscopy, electron microscopy and enzyme-linked immuno-absorbent assay (ELISA) were confronted with other methods used in other laboratories. Our results suggest that hippocampus is the most fragile for oxidative stress structure in human brain (the death of nervous cells in hippocampus leads to Alzheimer’s disease). Changes in iron metabolism were also found in substantia nigra (the death of nervous cells of this structure produces Parkinson’s disease) and in globus pallidus (neurodegeneration of this structure causes progressive supranuclear palsy). 相似文献
55.
Infrared spectra of perchlorate, halide and nitrate solutions in acetone are studied. The CO and CCC band frequency changes are discussed in terms of the electronic structure of acetone molecules complexed with cation and anion. The correlation between the shift of the CO and CCC bands and the reactivity of acetone molecules in aldolic condensation reaction is given. An explanation of the anion effect in aldolic condensation is proposed. 相似文献
56.
Microchimica Acta - An accurate and simple indirect method of flame-emission spectrometric determination of small quantities of elemental sulphur and many sulphur compounds, without their prior... 相似文献
57.
It is commonly taken for granted that long-time solutions of Cattaneo's hyperbolic heat conduction equation tend to overlap
the related parabolic solutions. Usually, for small times considerable qualitative as well as quantitative differences between
the hyperbolic and parabolic solutions are observed which vanish completely for large times. However, in the case of a heat
conducting body with the temperature dependent inner heat generation, the quantitative differences may grow with time. This
arises from the feedback between the temperature and the source capacity. To illustrate this effect, Cattaneo's hyperbolic
equation for the semi-infinite body, with the heat source which capacity is linearly dependent on temperature, is solved analytically
by the Laplace transforms method.
Received on 1 July 1997 相似文献
58.
59.
60.
Straksys Antanas Kavleiskaja Tatjana Gruskiene Ruta Badokas Kazimieras Sereikaite Jolanta 《Cellulose (London, England)》2022,29(16):8705-8718
Cellulose - The study aimed to propose a new system based on xylan for β-carotene delivery into aqueous environments. The xylan fraction of low molecular weight of... 相似文献