全文获取类型
收费全文 | 708篇 |
免费 | 38篇 |
国内免费 | 2篇 |
专业分类
化学 | 611篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 76篇 |
物理学 | 52篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 55篇 |
2021年 | 45篇 |
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 13篇 |
2017年 | 7篇 |
2016年 | 31篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 36篇 |
2012年 | 44篇 |
2011年 | 43篇 |
2010年 | 27篇 |
2009年 | 32篇 |
2008年 | 40篇 |
2007年 | 49篇 |
2006年 | 39篇 |
2005年 | 39篇 |
2004年 | 30篇 |
2003年 | 34篇 |
2002年 | 24篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有748条查询结果,搜索用时 31 毫秒
81.
Tiribilli Chiara Sokolová Romana Giannarelli Stefania Valášek Michal 《Monatshefte für Chemie / Chemical Monthly》2015,146(5):807-812
Monatshefte für Chemie - Chemical Monthly - The electrochemical reduction of diflunisal was studied in dimethyl sulfoxide on static mercury drop electrode. Diflunisal yields one irreversible... 相似文献
82.
Colloidal Surface Active Maghemite Nanoparticles for Biologically Safe CrVI Remediation: from Core‐Shell Nanostructures to Pilot Plant Development
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Massimiliano Magro Dr. Stefania Domeneghetti Davide Baratella Dr. Petr Jakubec Prof. Dr. Gabriella Salviulo Dr. Emanuela Bonaiuto Dr. Paola Venier Ondřej Malina Dr. Jiří Tuček Dr. Václav Ranc Dr. Giorgio Zoppellaro Prof.Dr. Radek Zbořil Prof. Dr. Fabio Vianello 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14219-14226
The present study is aimed at the exploration of achievable improvements for CrVI ex situ and in situ water remediation by using novel naked colloidal maghemite (γ‐Fe2O3) nanoparticles (surface active maghemite nanoparticles, SAMNs). The reliability of SAMNs for CrVI binding and removal was demonstrated, and SAMN@CrVI complex was characterized, as well as the covalent nature of the absorption was unequivocally proved. SAMNs were structurally and magnetically well conserved after CrVI binding. Thus, in consideration of their affinity for CrVI, SAMNs were exploited in a biological model system, mimicking a real in situ application. The assay evidenced a progressive reduction of revertant colonies of Salmonella typhimurium TA100 strain, as maghemite nanoparticles concentration increased, till the complete suppression of CrVI mutagen effect. Finally, an automatic modular pilot system for continuous magnetic removal and recovery of CrVI from water is proposed. SAMNs, thanks to their colloidal, binding, and catalytic properties, represent a promising tool as a reliable nanomaterial for water remediation by CrVI. 相似文献
83.
Dr. Andrew Ballard Dr. Stefania Narduolo Dr. Hiwa O. Ahmed Nathaniel I. Keymer Dr. Nabil Asaad Dr. David A. Cosgrove Dr. Niklaas J. Buurma Dr. Andrew G. Leach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3661-3687
The two enantiomers of a compound often have profoundly different biological properties and thus their liability to racemisation in aqueous solutions is an important piece of information. The authors reviewed the available data concerning the process of racemisation in vivo, in the presence of biological molecules (e.g., racemase enzymes, serum albumin, cofactors and derivatives) and under purely chemical but aqueous conditions (acid, base and other aqueous systems). Mechanistic studies are described critically in light of reported kinetic data. The types of experimental measurement that can be used to effectively determine rate constants of racemisation in various conditions are discussed and the data they provide is summarised. The proposed origins of enzymatic racemisation are presented and suggest ways to promote the process that are different from processes taking place in bulk water. Experimental and computational studies that provide understanding and quantitative predictions of racemisation risk are also presented. 相似文献
84.
Carla Ruggiero Stefania Ramirez Eric Ramazzotti Rita Mancini Roberto Muratori Maria Augusta Raggi Matteo Conti 《Journal of separation science》2020,43(8):1440-1449
In this work, a convenient method for the therapeutic monitoring of seven common antipsychotic drugs in “dried plasma spot” samples has been developed. It is based on the liquid chromatography tandem mass spectrometry technique, operating in multiple reaction monitoring mode, and a straightforward procedure for the simultaneous extraction of all antipsychotics in a single step, with high extraction yield. The method was fully validated with proper accuracy, precision, selectivity and sensitivity, for all the drugs. Limits of quantification were 0.12, 1.09, 1.46, 1.47, 5.70, 1.32, 1.33 µg/L for haloperidol, aripiprazole, olanzapine, quetiapine, clozapine, risperidone, and paliperidone, respectively. Accuracy, intra‐ and interday precision values were <10% for all drugs at all concentration levels examined. The method was tested in the analysis of 30 plasma samples from real patients for each drug. The proposed analytical approach, by combining practical and logistical advantages of microsampling with liquid chromatography tandem mass spectrometry analytical performance, could offer an ideal strategy for accurate and timely therapeutic drug monitoring of antipsychotic drugs in most clinical settings, even in remote centers and/or in out‐patient settings, bringing so many potential improvements in psychiatric patient care. 相似文献
85.
Alessandro Allegri Valeriia Maslova Magda Blosi Anna Luisa Costa Simona Ortelli Francesco Basile Stefania Albonetti 《Molecules (Basel, Switzerland)》2020,25(22)
The photocatalytic oxidation of biomass-derived building blocks such as 5-hydroxymethylfurfural (HMF) is a promising reaction for obtaining valuable chemicals and the efficient long-term storage of solar radiation. In this work, we developed innovative TiO2-based materials capable of base-free HMF photo-oxidation in water using simulated solar irradiation. The materials were prepared by combining microemulsion and spray-freeze drying (SFD), resulting in highly porous systems with a large surface area. The effect of titania/silica composition and the presence of gold-copper alloy nanoparticles on the properties of materials as well as photocatalytic performance were evaluated. Among the lab-synthesized photocatalysts, Ti15Si85 SFD and Au3Cu1/Ti15Si85 SFD achieved the higher conversions, while the best selectivity was observed for Au3Cu1/Ti15Si85 SFD. The tests with radical scavengers for both TiO2-m and Au3Cu1/Ti15Si85 SFD suggested that primary species responsible for the selective photo-oxidation of HMF are photo-generated electrons and/or superoxide radicals. 相似文献
86.
Corrigendum: Labeling and Selective Inactivation of Gram‐Positive Bacteria Employing Bimodal Photoprobes with Dual Readouts
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Anzhela Galstyan Dr. Desiree Block Dr. Silke Niemann Dr. Malte C. Grüner Prof.Dr. Stefania Abbruzzetti Michele Oneto Dr. Constantin G. Daniliuc Dr. Sven Hermann Prof.Dr. Cristiano Viappiani Prof.Dr. Michael Schäfers Prof.Dr. Bettina Löffler Priv.‐Doz.Dr. Cristian A. Strassert Dr. Andreas Faust 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9051-9051
87.
Stefano Federico Tuhina Khan Nicola Relitti Giulia Chemi Margherita Brindisi Simone Brogi Ettore Novellino Daniela M. Zisterer Giuseppe Campiani Sandra Gemma Stefania Butini 《Tetrahedron letters》2018,59(51):4466-4470
We developed a Jocic-type protocol for the construction of the pyrrolonaphthoxazepine (PNOX) core. After an initial investigation based on the isolation of a trichloromethyl carbinol derivative, we shifted our attention towards a multicomponent single-step protocol. Screening of a variety of bases and solvents led to the identification of the optimum conditions for the preparation of the key α-aryloxy carboxylic acids to undergo intramolecular cyclization. The novel chemical route significantly improved overall yields for the preparation of PNOX-based compounds and was successfully extended to the preparation of 1,4-benzoxazinone-based templates. 相似文献
88.
Stefania Garzoli Mijat Božović Anna Baldisserotto Manuela Sabatino Stefania Cesa Federico Pepi 《Natural product research》2018,32(11):1254-1259
A comprehensive study on essential oil samples of Foeniculum vulgare Miller from Tarquinia (Italy) is reported. A 24-h systematic steam distillation was performed on different harvested samples applying different extraction times. The GC-MS analysis of the residue outcome showed o-cymene, α-phellandrene, α-pinene and estragole as the major constituents. The predominance and continued presence of o-cymene makes this fennel oil a rather unique chemotype. An evident correlation between the antifungal activity and phenological stage is demonstrated. The most active fractions were particularly rich in estragole, as well as a significant amount of fenchone that possibly exerts some additive effect in the expression of overall antifungal potency. Pre-fruiting material produced oil particularly rich in o-cymene. With reference to the duration of the extraction, the maximum amount of oil was released within the first 3 h, whereas the reproductive phase material needed at least 6 h for the extraction. 相似文献
89.
Quantitative Prediction of Rate Constants for Aqueous Racemization To Avoid Pointless Stereoselective Syntheses
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Andrew Ballard Dr. Hiwa O. Ahmad Dr. Stefania Narduolo Lucy Rosa Nikki Chand Dr. David A. Cosgrove Dr. Peter Varkonyi Dr. Nabil Asaad Dr. Simone Tomasi Dr. Niklaas J. Buurma Dr. Andrew G. Leach 《Angewandte Chemie (International ed. in English)》2018,57(4):982-985
Racemization has a large impact upon the biological properties of molecules but the chemical scope of compounds with known rate constants for racemization in aqueous conditions was hitherto limited. To address this remarkable blind spot, we have measured the kinetics for racemization of 28 compounds using circular dichroism and 1H NMR spectroscopy. We show that rate constants for racemization (measured by ourselves and others) correlate well with deprotonation energies from quantum mechanical (QM) and group contribution calculations. Such calculations thus provide predictions of the second‐order rate constants for general‐base‐catalyzed racemization that are usefully accurate. When applied to recent publications describing the stereoselective synthesis of compounds of purported biological value, the calculations reveal that racemization would be sufficiently fast to render these expensive syntheses pointless. 相似文献
90.
Zotti M Schiavone S Tricarico F Colaianna M D'Apolito O Paglia G Corso G Trabace L 《Journal of separation science》2008,31(13):2511-2515
Nitric oxide (NO) is one of the most important mediators and neurotransmitters and its levels change under pathological conditions. NO production may be regulated by endogenous nitric oxide synthase (NOS) inhibitors, in particular asymmetric dimethylarginine (ADMA). Most of the interest is focused on ADMA, since this compound is present in plasma and urine and accumulation of ADMA has been described in many disease states but little is known about cerebrospinal fluid (CSF) concentrations of this compound and of its structural isomer symmetric dimethylarginine (SDMA). To determine the levels of methylarginines, we here present a new hydrophilic interaction chromatography (HILIC)-MS/MS method for the precise determination of these substances in CSF from microdialysis samples of rat prefrontal cortex (PFC). The method requires only minimal sample preparation and features isotope-labelled internal standards. 相似文献