全文获取类型
收费全文 | 153篇 |
免费 | 2篇 |
专业分类
化学 | 58篇 |
力学 | 21篇 |
数学 | 37篇 |
物理学 | 39篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2009年 | 3篇 |
2008年 | 10篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 12篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1948年 | 1篇 |
1947年 | 1篇 |
1942年 | 1篇 |
1937年 | 2篇 |
1936年 | 2篇 |
1917年 | 1篇 |
1893年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 78 毫秒
1.
G. Giardina G. Fazio A. Lamberto A. I. Muminov A. K. Nasirov U. T. Yakhshiev R. Palamara R. Ruggeri 《Acta Physica Hungarica A》2004,19(1-2):101-108
We study the effect of the entrance channel and the shell structure of reacting massive nuclei on the fusion mechanism and the formation of evaporation residues of heavy and superheavy nuclei. In the framework of the combined dinuclear system concept and advanced statistical model, we analyze the reactions 32S+182W, 48Ti+166Er and 60Ni+154Sm leading to 214Th*, and the reactions 48Ca+248Cm and the 48Ca+249Cf leading to the 296116 and 297118 compound nuclei, respectively. 相似文献
2.
A study has been made of the cationic electropolymerization of trans-anethole initiated by a direct electron transfer mechanism at a Pt anode in 1,2-dichloroethane solution with tetrabutylammonium perchlorate as supporting electrolyte. The electrochemical behaviour of the system has been preliminarily investigated by voltammetry at rotating and stationary Pt electrode and also by chronoamperometry. The results are consistent with an ECE oxidation process of anethole with formation first of a radical cation and finally of a dication. Polymerization experiments by electrolysis at the oxidation potential of the monomer have been also carried out both under continuous electrolysis and with short initial pulses of current. The results have been analysed and some kinetic parameters of the system have been evaluated. 相似文献
3.
After our article, Physica A 391 (2012) 107–112, had been published online, T. Hillen told us about a theorem by Osaki, relevant for our numerical simulations. 相似文献
4.
Assessment of pharmacokinetic interaction between piracetam and l‐carnitine in healthy subjects
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Gustavo D. Mendes Gabriela Traldi Zaffalon Antonio Sérgio Silveira Juliana Cama Ramacciato Rogério Heládio Lopes Motta Thiago Gagliano‐Jucá Anibal Gil Lopes José Cássio de Almeida Magalhães Gilberto De Nucci 《Biomedical chromatography : BMC》2016,30(4):536-542
A rapid, sensitive and specific method for quantifying piracetam in human plasma using Piracetam d‐8 as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by one‐step precipitation of protein using an acetonitrile (100%). The extracts were analyzed by high‐performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC‐MS/MS). The method had a chromatographic run time of 3.8 min and a linear calibration curve over the range 0.5–50 µg/mL (r > 0.99). This LC‐MS‐MS procedure was used to assess the bioavailability of two piracetam formulations: piracetam + l‐carnitine (Piracar®; 270/330 mg tablet) and piracetam (Nootropil®; 800 mg tablet) in healthy volunteers of both sexes. The geometric means with corresponding 90% confidence interval (CI) for test/reference percentage ratios were 88.49% (90% CI = 81.19 – 96.46) for peak concentration/dose and 102.55% (90% CI = 100.62 – 104.51) for AUCinf/dose. The limit of quantitation of 0.5 µg/mL is well suited for pharmacokinetic studies in healthy volunteers. It was concluded that piracetam (Piracar®; 270/330 mg tablet) has a bioavailability equivalent to the piracetam (Nootropil®; 800 mg tablet) formulation with regard to both the rate and the extent of absorption. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
Prof. Gianlorenzo Bussetti Claudia Filoni Prof. Andrea Li Bassi Dr. Alberto Bossi Prof. Marcello Campione Prof. Alessio Orbelli Biroli Prof. Chiara Castiglioni Dr. Silvia Trabattoni Dr. Stefania De Rosa Prof. Luca Tortora Prof. Franco Ciccacci Prof. Lamberto Duò 《ChemistryOpen》2021,10(8):748-755
We have recently discussed how organic nanocrystal dissolution appears in different morphologies and the role of the solution pH in the crystal detriment process. We also highlighted the role of the local molecular chemistry in porphyrin nanocrystals having comparable structures: in water-based acid solutions, protonation of free-base porphyrin molecules is the driving force for crystal dissolution, whereas metal (ZnII) porphyrin nanocrystals remain unperturbed. However, all porphyrin types, having an electron rich π-structure, can be electrochemically oxidized. In this scenario, a key question is: does electrochemistry represent a viable strategy to drive the dissolution of both free-base and metal porphyrin nanocrystals? In this work, by exploiting electrochemical atomic force microscopy (EC-AFM), we monitor in situ and in real time the dissolution of both free-base and metal porphyrin nanocrystals, as soon as molecules reach the oxidation potential, showing different regimes according to the applied EC potential. 相似文献
6.
Alyssa B. Sanders Jacob T. Zangaro Nakoa K. Webber Ryan P. Calhoun Elizabeth A. Richards Samuel L. Ricci Hannah M. Work Daniel D. Yang Kaitlyn R. Casey Joseph C. Iovine Gabriela Baker Taylor V. Douglas Sierra B. Dutko Thomas J. Fasano Sarah A. Lofland Ashley A. Rajan Mihaela A. Vasile Benjamin R. Carone Nathaniel V. Nucci 《Molecules (Basel, Switzerland)》2022,27(5)
Despite considerable advances in recent years, challenges in delivery and storage of biological drugs persist and may delay or prohibit their clinical application. Though nanoparticle-based approaches for small molecule drug encapsulation are mature, encapsulation of proteins remains problematic due to destabilization of the protein. Reverse micelles composed of decylmonoacyl glycerol (10MAG) and lauryldimethylamino-N-oxide (LDAO) in low-viscosity alkanes have been shown to preserve the structure and stability of a wide range of biological macromolecules. Here, we present a first step on developing this system as a future platform for storage and delivery of biological drugs by replacing the non-biocompatible alkane solvent with solvents currently used in small molecule delivery systems. Using a novel screening approach, we performed a comprehensive evaluation of the 10MAG/LDAO system using two preparation methods across seven biocompatible solvents with analysis of toxicity and encapsulation efficiency for each solvent. By using an inexpensive hydrophilic small molecule to test a wide range of conditions, we identify optimal solvent properties for further development. We validate the predictions from this screen with preliminary protein encapsulation tests. The insight provided lays the foundation for further development of this system toward long-term room-temperature storage of biologics or toward water-in-oil-in-water biologic delivery systems. 相似文献
7.
The phytochemical study of aerial parts of Viburnum sargenti Koehne, a species spontaneous in Mongolia and Northern China, led to the isolation of three iridoid glucosides of Valeriana-type: the novel 7,10,2'-triacetylsuspensolide F, 1, and the known viburtinoside IV and V. In addition, (+)-epicatechin was also isolated. 相似文献
8.
Bianco A Guiso M Ballero M Foddai S Nicoletti M Piccin A Serafini M Tomassini L 《Natural product research》2004,18(3):241-246
During our systematic study on the species of genus Linaria (Scrophulariaceae) present in Italy, we examined the glycosidic fraction of Linaria capraria Moris et De Not., a species endemic of Tuscany archipelago. This fraction is particularly complex and we considered in this article only the medium polarity components. In accordance with previous studies, L. capraria shows acyl derivatives of antirrhinoside 1 as specific chemotaxonomic iridoidic markers. L. capraria exhibits a complex composition, with regard to iridoidic constituents, with several chromatographic problems to be resolved. We then isolated, besides the known antirrhinoside 1, two acyl derivatives of antirrhinoside, the 6'-O-senecioyl derivative, 2, and the 6'-O-angeloyl derivative, 3. In addition a glucoside of an acyclic monoterpene, 4, was also isolated, which may be correlated to the other monoterpenic glycosides isolated from other species of Scrophulariaceae. 相似文献
9.
10.
The nature of water's interaction with biomolecules such as proteins has been difficult to examine in detail at atomic resolution. Solution NMR spectroscopy is potentially a powerful method for characterizing both the structural and temporal aspects of protein hydration but has been plagued by artifacts. Encapsulation of the protein of interest within the aqueous core of a reverse micelle particle results in a general slowing of water dynamics, significant reduction in hydrogen exchange chemistry and elimination of contributions from bulk water thereby enabling the use of nuclear Overhauser effects to quantify interactions between the protein surface and hydration water. Here we extend this approach to allow use of dipolar interactions between hydration water and hydrogens bonded to protein carbon atoms. By manipulating the molecular reorientation time of the reverse micelle particle through use of low viscosity liquid propane, the T(1ρ) relaxation time constants of (1)H bonded to (13)C were sufficiently lengthened to allow high quality rotating frame nuclear Overhauser effects to be obtained. These data supplement previous results obtained from dipolar interactions between the protein and hydrogens bonded to nitrogen and in aggregate cover the majority of the molecular surface of the protein. A wide range of hydration dynamics is observed. Clustering of hydration dynamics on the molecular surface is also seen. Regions of long-lived hydration water correspond with regions of the protein that participate in molecular recognition of binding partners suggesting that the contribution of the solvent entropy to the entropy of binding has been maximized through evolution. 相似文献