全文获取类型
收费全文 | 1759篇 |
免费 | 88篇 |
国内免费 | 3篇 |
专业分类
化学 | 1461篇 |
晶体学 | 15篇 |
力学 | 21篇 |
数学 | 143篇 |
物理学 | 210篇 |
出版年
2023年 | 26篇 |
2022年 | 68篇 |
2021年 | 107篇 |
2020年 | 66篇 |
2019年 | 56篇 |
2018年 | 60篇 |
2017年 | 31篇 |
2016年 | 100篇 |
2015年 | 56篇 |
2014年 | 81篇 |
2013年 | 116篇 |
2012年 | 115篇 |
2011年 | 134篇 |
2010年 | 82篇 |
2009年 | 67篇 |
2008年 | 114篇 |
2007年 | 84篇 |
2006年 | 86篇 |
2005年 | 78篇 |
2004年 | 62篇 |
2003年 | 44篇 |
2002年 | 28篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 18篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1981年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1960年 | 2篇 |
1941年 | 2篇 |
排序方式: 共有1850条查询结果,搜索用时 250 毫秒
991.
Ivan V. Smolyaninov Natalia A. Antonova Andrey I. Poddel'sky Viktoria P. Osipova Nadezhda T. Berberova Yuri T. Pimenov 《应用有机金属化学》2012,26(6):277-283
A number of catecholates (complexes 1–3, 6) and o‐amidophenolates (complexes 4, 5) of triphenylantimony(V) was examined in the process of lipid peroxidation of liver homogenates and sperm of Russian sturgeon (Acipenser gueldenstaedti B.), and human red blood cells. It was shown that the influence of complexes 1–6 on lipid peroxidation process in model systems depends on the nature of redox‐active ligand and varies from weak anti‐ and pro‐oxidant (catecholates 1, 6) to pronounced antioxidant (catecholates and o‐amidophenolates 2–5). It was found that the complexes 2–5 are the more effective inhibitors of lipid peroxidation than standard antioxidant ionol. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
992.
Wageiha Mosslehy Natalia Voskoboynikova Alexandr Colbasevici Adrian Ricke Daniel Klose Johann P. Klare Armen Y. Mulkidjanian Heinz‐Jürgen Steinhoff 《Photochemistry and photobiology》2019,95(5):1195-1204
Styrene–maleic acid lipid particles (SMALPs) provide stable water‐soluble nanocontainers for lipid‐encased membrane proteins. Possible effects of the SMA‐stabilized lipid environment on the interaction dynamics between functionally coupled membrane proteins remain to be elucidated. The photoreceptor sensory rhodopsin II, NpSRII and its cognate transducer, NpHtrII, of Natronomonas pharaonis form a transmembrane complex, NpSRII2/NpHtrII2 that plays a key role in negative phototaxis and provides a unique model system to study the light‐induced transfer of a conformational signal between two integral membrane proteins. Photon absorption induces transient structural changes in NpSRII comprising an outward movement of helix F that cause further conformational alterations in NpHtrII. We applied site‐directed spin labeling and time‐resolved optical and EPR spectroscopy to compare the conformational dynamics of NpSRII2/NpHtrII2 reconstituted in SMALPs with that of nanolipoprotein particle and liposome preparations. NpSRII and NpSRII2/NpHtrII2 show similar photocycles in liposomes and nanolipoprotein particles. An accelerated decay of the M photointermediate found for SMALPs can be explained by a high local proton concentration provided by the carboxylic groups of the SMA polymer. Light‐induced large‐scale conformational changes of NpSRII2/NpHtrII2 observed in liposomes and nanolipoprotein particles are affected in SMALPs, indicating restrictions of the protein's conformational freedom. 相似文献
993.
Alexandra Ya. Rak Evgeny A. Protasov Alexander V. Trofimov Natalia V. Pigareva Alexander M. Ischenko 《Biomedical chromatography : BMC》2022,36(2):e5259
Anti-mullerian hormone (AMH) is one of the least studied members of transforming growth factor beta superfamily showing pro-apoptotic activity against cells positive for hormone type II receptor overexpressed by malignant cells in many cancer cases. Here, we propose an improved method for isolation of recombinant C-terminal AMH fragment (C-rAMH) to obtain homogeneous preparations of this protein with high biological activity. In contrast to our previously developed C-rAMH purification technology based on reversed-phase HPLC, the key stage of the new approach is hydrophobic interaction chromatography using Toyopearl Butyl-650S resin performed under more benign conditions. This modification of the previously developed method allowed highly purified C-rAMH to be obtained that is characterized by twice the specificity estimated as the ability to bind to the recombinant analog of AMH type II receptor and by significantly higher biological activity, that is, the ability to induce the death of target cells. Thus, we made the purification technology even more cost-effective and suitable for the production of drug forms based on C-rAMH. 相似文献
994.
Rozhkova Alexandra K. Kuzmenkova Natalia V. Sibirtsev Alexander M. Petrov Vladimir G. Shi Keliang L. Hou Xiaolin L. Kalmykov Stepan N. 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2037-2044
Journal of Radioanalytical and Nuclear Chemistry - Monitoring of radionuclide concentration in natural samples is important for assessing environmental safety. The low concentration of long-lived... 相似文献
995.
Investigation of the resonance‐assisted hydrogen bond in model β‐diketones through localized molecular orbital analysis of the spin–spin coupling constants related to the O–H · · · O hydrogen bond
下载免费PDF全文
![点击此处可从《Magnetic resonance in chemistry : MRC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The resonance‐assisted hydrogen bond (HB) phenomenon has been studied theoretically by a localized molecular orbital (LMO) decomposition of the spin–spin coupling constants between atoms either involved or close to the O–H · · · O system of some β‐diketones and their saturated counterparts. The analysis, carried out at the level of the second‐order polarization propagator approximation, shows that the contributions in terms of LMO to the paramagnetic spin orbital and the spin dipolar Ramsey terms proof the importance of the delocalized π‐electron structure supporting the idea of the existence of the resonance‐assisted HB phenomenon phenomenon. The LMO contributions to the Fermi contact term indicate mainly the presence of the HB that may or not be linked to the π‐electrons. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
996.
Syrota Natalia А. Kemskiy Sergiy V. Bol’but Andriy V. Vovk Mikhailo V. 《Chemistry of Heterocyclic Compounds》2019,55(11):1092-1097
Chemistry of Heterocyclic Compounds - The corresponding ethyl 5-carbonylglycinates were synthesized by condensation of 4-(Boc-amino)-1,2,3-triazole-5-carboxylic acids with ethyl glycinate... 相似文献
997.
Elena M. Gmez-Sez Natalia Moratalla-Lpez Cndida Lorenzo Herminia Vergara Gonzalo L. Alonso 《Molecules (Basel, Switzerland)》2021,26(7)
At present, the development of new agri-food products, including flavored meat products presented in ready-to-eat vacuum packs, is encouraged. The addition of ingredients used as flavoring agents creates the need to be able to determine the volatile compounds responsible for their characteristic aroma. The aim of this study is to propose, develop, and validate a new method that uses headspace-stir bar sorptive extraction-gas chromatography/mass spectrometry (HS-SBSE-GC/MS) to determine the saffron aroma in cured ham flavored with this spice. Results showed that safranal was the main volatile compound that could be identified and quantified in cured ham flavored with saffron. This analytical method was adequate in terms of linearity, selectivity, sensitivity, and accuracy. To our knowledge, this is the first time that an HS-SBSE-GC/MS method for determining the saffron aroma of flavored cured ham has been developed and validated, and it is of interest to agri-food industries. 相似文献
998.
Tatyana N. Lomova Maria E. Klyueva Elena Yu. Tyulyaeva Natalia G. Bichan Svetlana V. Zaitseva Sergey A. Zdanovich 《Mendeleev Communications》2012,22(5):281-283
The H-associate as a new protonated form of metalloporphyrins in strong acid media has been obtained and a qualitative reaction for its determination has been found; the properties and structure of a protonated form have been analyzed by spectral methods and quantum-chemical calculations. 相似文献
999.
1000.
Maxim Bykov Stella Chariton Elena Bykova Saiana Khandarkhaeva Timofey Fedotenko Alena V. Ponomareva Johan Tidholm Ferenc Tasndi Igor A. Abrikosov Pavel Sedmak Vitali Prakapenka Michael Hanfland Hanns‐Peter Liermann Mohammad Mahmood Alexander F. Goncharov Natalia Dubrovinskaia Leonid Dubrovinsky 《Angewandte Chemie (International ed. in English)》2020,59(26):10666-10666