全文获取类型
收费全文 | 785篇 |
免费 | 36篇 |
国内免费 | 3篇 |
专业分类
化学 | 630篇 |
力学 | 3篇 |
数学 | 28篇 |
物理学 | 163篇 |
出版年
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 27篇 |
2020年 | 23篇 |
2019年 | 17篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 42篇 |
2015年 | 28篇 |
2014年 | 21篇 |
2013年 | 56篇 |
2012年 | 51篇 |
2011年 | 63篇 |
2010年 | 42篇 |
2009年 | 22篇 |
2008年 | 40篇 |
2007年 | 31篇 |
2006年 | 30篇 |
2005年 | 23篇 |
2004年 | 25篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1992年 | 6篇 |
1990年 | 14篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1980年 | 5篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1971年 | 5篇 |
1969年 | 3篇 |
1968年 | 7篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1962年 | 4篇 |
1960年 | 6篇 |
1959年 | 3篇 |
1957年 | 8篇 |
1923年 | 3篇 |
排序方式: 共有824条查询结果,搜索用时 250 毫秒
1.
The effect of non‐thermal plasma generated by the direct current (DC) corona discharge in the mode of transition spark is studied on a yeast Saccharomyces cerevisiae. The exposure to plasma increases production of reactive oxygen species (ROS) in cells, possibly causing the induction of apoptosis. To clarify the mechanism of apoptosis, its induction is tested not only on a wild strain of S. cerevisiae, but also on mutant strains: A deletion mutant Δyca1 without yeast metacaspase proves that in S. cerevisiae the apoptosis occurs partly by the caspase‐independent pathway. A petite strains with mutation in the mitochondria do not show pronounced ROS formation, but in spite of this, apoptosis is detected. Hence, mitochondrial ROS probably do not play an important role in induction of apoptosis. 相似文献
2.
Highly Axial Magnetic Anisotropy in a N3O5 Dysprosium(III) Coordination Environment Generated by a Merocyanine Ligand 下载免费PDF全文
Pramila Selvanathan Gang Huang Thierry Guizouarn Dr. Thierry Roisnel Dr. Guglielmo Fernandez‐Garcia Dr. Federico Totti Dr. Boris Le Guennic Dr. Guillaume Calvez Dr. Kévin Bernot Dr. Lucie Norel Prof. Stéphane Rigaut 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15222-15226
A spiropyran‐based switchable ligand isomerizes upon reaction with lanthanide(III) precursors to generate complexes with an unusual N3O5 coordination sphere. The air‐stable dysprosium(III) complex shows a hysteresis loop at 2 K and a very strong axial magnetic anisotropy generated by the merocyanine phenolate donor. 相似文献
3.
Neubertov Viktorie Slepikov Kaslkov Nikola Vokat Barbora Bakov Lucie vork Vclav Kolsk Zdeka 《Cellulose (London, England)》2022,29(3):1405-1418
Cellulose - This work is devoted to the study of surface properties of cellulose before and after a surface modification. Surface modification of polymeric materials was carried out in two steps:... 相似文献
4.
Dr. Lenka Štacková Marina Russo Dr. Lucie Muchová Vojtěch Orel Prof. Libor Vítek Dr. Peter Štacko Prof. Petr Klán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13184-13190
Carbon monoxide (CO) is an endogenous signaling molecule that controls a number of physiological processes. To circumvent the inherent toxicity of CO, light-activated CO-releasing molecules (photoCORMs) have emerged as an alternative for its administration. However, their wider application requires photoactivation using biologically benign visible and near-infrared (NIR) light. In this work, a strategy to access such photoCORMs by fusing two CO-releasing flavonol moieties with a NIR-absorbing cyanine dye is presented. These hybrids liberate two molecules of CO in high chemical yields upon activation with NIR light up to 820 nm and exhibit excellent uncaging cross-sections, which surpass the state-of-the-art by two orders of magnitude. Furthermore, the biocompatibility and applicability of the system in vitro and in vivo are demonstrated, and a mechanism of CO release is proposed. It is hoped that this strategy will stimulate the discovery of new classes of photoCORMs and accelerate the translation of CO-based phototherapy into practice. 相似文献
5.
High‐throughput workflow for identification of phosphorylated peptides by LC‐MALDI‐TOF/TOF‐MS coupled to in situ enrichment on MALDI plates functionalized by ion landing 下载免费PDF全文
Lukáš Krásný Petr Pompach Marcela Strnadová Radovan Hynek Karel Vališ Vladimír Havlíček Petr Novák Michael Volný 《Journal of mass spectrometry : JMS》2015,50(6):802-811
We report an MS‐based workflow for identification of phosphorylated peptides from trypsinized protein mixtures and cell lysates that is suitable for high‐throughput sample analysis. The workflow is based on an in situ enrichment on matrix‐assisted laser desorption/ionization (MALDI) plates that were functionalized by TiO2 using automated ion landing apparatus that can operate unsupervised. The MALDI plate can be functionalized by TiO2 into any array of predefined geometry (here, 96 positions for samples and 24 for mass calibration standards) made compatible with a standard MALDI spotter and coupled with high‐performance liquid chromatography. The in situ MALDI plate enrichment was compared with a standard precolumn‐based separation and achieved comparable or better results than the standard method. The performance of this new workflow was demonstrated on a model mixture of proteins as well as on Jurkat cells lysates. The method showed improved signal‐to‐noise ratio in a single MS spectrum, which resulted in better identification by MS/MS and a subsequent database search. Using the workflow, we also found specific phosphorylations in Jurkat cells that were nonspecifically activated by phorbol 12‐myristate 13‐acetate. These phosphorylations concerned the mitogen‐activated protein kinase/extracellular signal‐regulated kinase signaling pathway and its targets and were in agreement with the current knowledge of this signaling cascade. Control sample of non‐activated cells was devoid of these phosphorylations. Overall, the presented analytical workflow is able to detect dynamic phosphorylation events in minimally processed mammalian cells while using only a short high‐performance liquid chromatography gradient. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Zsombor Gonda Dr. Zoltán Novák 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16801-16806
A new synthetic method was developed for the N‐arylation of pyrazoles using diaryliodonium salts. The transformation does not require any transition‐metal catalyst and provides the desired N‐arylpyrazoles rapidly under mild reaction condition in the presence of aqueous ammonia solution as a mild base without the use of inert atmosphere. The chemoselectivity of unsymmetric diaryliodonium salts was also explored with large number of examples. 相似文献
7.
High Performance Liquid Chromatography/Electrochemistry/High Resolution Electrospray Ionization‐Mass Spectrometry (HPLC/EC/HR ESI‐MS) Characterization of Selected Cytokinins Oxidation Products 下载免费PDF全文
Michal Karady Ondřej Novák Aleš Horna Miroslav Strnad Karel Doležal 《Electroanalysis》2015,27(2):406-414
Electrochemistry combined with mass spectrometry represents an emerging analytical technique used to study the oxidation pathway of various drugs and in vivo occurring compounds, continuously showing a capability to generate many known metabolites or new oxidation products. An on‐line HPLC/EC/HR ESI‐MS method had been used to investigate the oxidation of selected cytokinin compounds. This setup allowed rapid identification and general structure elucidation of the obtained products. An electrochemical oxidation of isopentenyladenine resulted in five products, including hydroxylated and dehydrogenated products, which correlates very well with its in vivo metabolism. Electrochemical conversion of trans‐zeatin revealed six products, with two dehydrogenation products corresponding to its in vivo occurring metabolites. cis‐Zeatin oxidation in the electrochemical cell gave rise to eight products, resembling similarity to trans‐zeatin oxidation. All three compounds underwent a complete turnover mainly through two oxidation reactions occurring in the electrochemical cell? dehydrogenation and a less typical aliphatic hydroxylation. The resulting products are in correlation with their known in vivo metabolism. 相似文献
8.
Fashina Bidemi Novák František Kučerík Jiří 《Journal of Thermal Analysis and Calorimetry》2021,145(6):3031-3039
Journal of Thermal Analysis and Calorimetry - In arid soils, humic acids (HAs) are used as amendments to improve water uptake from the atmosphere. This method of harvesting water involves several... 相似文献
9.
Pavlína Peikertová Lenka Kulhánková Lucie Neuwirthová Jonáš Tokarský 《Chemical Papers》2017,71(2):379-385
Conducting polymer polyaniline which is nowadays in forefront of the interest was in our study prepared in a form of thin films from anilinium sulfate by its chemical oxidation using ammonium peroxydisulfate. During the oxidation process, the polyaniline was deposited on glass slides and immersed into reaction mixture. Two sets of polyaniline thin films were prepared with different oxidation times (10, 20, 30, and 40 min). The first set was kept dry in desiccator and the second one was freely exposed to air moisture. Raman spectroscopy, nondestructive technique which is very sensitive to changes in structure of polymers, was used for the characterization of the protonation state of prepared polyaniline thin films. It was found that storage conditions affect the protonation state which in case of samples kept in desiccator is maintained without significant changes for longer time. Raman spectroscopy also revealed the dependence of protonation state on the oxidation time and 10 min proved as not sufficient for the creation of the protonation form of polyaniline. 相似文献
10.
Ms. Orsolya Tischler Mr. Balázs Tóth Dr. Zoltán Novák 《Chemical record (New York, N.Y.)》2017,17(2):184-199
This account collects the developments and transformations which avoid the utilization of harsh reaction conditions in the field of palladium catalyzed, ortho‐directed C?H activation of aniline derivatives from the first attempts to up‐to‐date results, including the results of our research laboratory. The discussed functionalizations performed under mild conditions include acylation, olefination, arylation, alkylation, alkoxylation reactions. Beside the optimization studies and the synthetic applications mechanistic investigations are also presented. 相似文献