全文获取类型
收费全文 | 1127篇 |
免费 | 52篇 |
国内免费 | 5篇 |
专业分类
化学 | 913篇 |
力学 | 19篇 |
数学 | 104篇 |
物理学 | 148篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 58篇 |
2021年 | 82篇 |
2020年 | 31篇 |
2019年 | 38篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 42篇 |
2015年 | 40篇 |
2014年 | 41篇 |
2013年 | 53篇 |
2012年 | 79篇 |
2011年 | 93篇 |
2010年 | 58篇 |
2009年 | 53篇 |
2008年 | 78篇 |
2007年 | 83篇 |
2006年 | 47篇 |
2005年 | 61篇 |
2004年 | 49篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 15篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有1184条查询结果,搜索用时 31 毫秒
941.
Chiara Lambruschini Ilaria Demori Zeinab El Rashed Leila Rovegno Elena Canessa Katia Cortese Elena Grasselli Lisa Moni 《Molecules (Basel, Switzerland)》2021,26(1)
The Ugi four-component reaction employing naturally occurred ferulic acid (FA) is proposed as a convenient method to synthesize feruloyl tertiary amides. Applying this strategy, a peptoid-like derivative of ferulic acid (FEF77) containing 2 additional hydroxy-substituted aryl groups, has been synthesized. The influence of the configuration of the double bond of ferulic acid and feruloyl amide on the antioxidant activity has been investigated thanks to light-mediated isomerization studies. At the cellular level, both FA, trans and cis isomers of FEF77 were able to protect human endothelial cord vein (HECV) cells from the oxidative damage induced by exposure to hydrogen peroxide, as measured by cell viability and ROS production assays. Moreover, in steatotic FaO rat hepatoma cells, an in vitro model resembling non-alcoholic fatty liver disease (NAFLD), the molecules exhibited a lipid-lowering effect, which, along with the antioxidant properties, points to consider feruloyl amides for further investigations in a therapeutic perspective. 相似文献
942.
Giuliana Ferrante Rossana Rossi Giovanna Cilluffo Dario Di Silvestre Andrea Brambilla Antonella De Palma Chiara Villa Velia Malizia Rosalia Gagliardo Yvan Torrente Giovanni Corsello Giovanni Viegi Pierluigi Mauri Stefania La Grutta 《Molecules (Basel, Switzerland)》2021,26(5)
Urine proteomic applications in children suggested their potential in discriminating between healthy subjects from those with respiratory diseases. The aim of the current study was to combine protein fractionation, by urinary extracellular vesicle isolation, and proteomics analysis in order to establish whether different patterns of respiratory impedance in healthy preschoolers can be characterized from a protein fingerprint. Twenty-one 3–5-yr-old healthy children, representative of 66 recruited subjects, were selected: 12 late preterm (LP) and 9 full-term (T) born. Children underwent measurement of respiratory impedance through Forced Oscillation Technique (FOT) and no significant differences between LP and T were found. Unbiased clustering, based on proteomic signatures, stratified three groups of children (A, B, C) with significantly different patterns of respiratory impedance, which was slightly worse in group A than in groups B and C. Six proteins (Tripeptidyl peptidase I (TPP1), Cubilin (CUBN), SerpinA4, SerpinF1, Thy-1 membrane glycoprotein (THY1) and Angiopoietin-related protein 2 (ANGPTL2)) were identified in order to type the membership of subjects to the three groups. The differential levels of the six proteins in groups A, B and C suggest that proteomic-based profiles of urinary fractionated exosomes could represent a link between respiratory impedance and underlying biological profiles in healthy preschool children. 相似文献
943.
944.
Anna Maria Ranieri Chiara Caporale Valentina Fiorini Alysia Hubbard Paul Rigby Stefano Stagni Elizabeth Watkin Mark I. Ogden Mark J. Hackett Massimiliano Massi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10566-10570
A family of three neutral iridium(III) tetrazolato complexes are investigated as bacterial imaging agents. The complexes offer a facile tuning of the emission colour from green (520 nm) to red (600 nm) in aqueous media, while keeping the excitation wavelength unchanged. The three complexes do not inhibit the bacterial growth of Bacillus Cereus, used as a model in this study, and exhibit extremely fast cellular uptake. After a minute incubation time, the nontoxic complexes show subcellular localisation in spherical structures identified as lipid vacuoles. Confocal Raman imaging has been exploited for the first time on live bacteria, to provide direct and label-free mapping of the lipid-enriched organelles within B. cereus, complementing the use of luminescent probes. Examination of the Raman spectra not only confirmed the presence of lipophilic inclusions in B. cereus but offered additional information about their chemical composition, suggesting that the lipid vacuoles may contain polyhydroxybutyrate (PHB). 相似文献
945.
Manuela Simonato Francesca Ricci Chiara Catozzi Matteo Storti Sonia Giambelluca Alessio Correani Fabrizio Salomone Paola Cogo Virgilio Carnielli 《Journal of mass spectrometry : JMS》2022,57(2):e4808
Stable isotope tracing can be safely used for metabolic studies in animals and humans. The endogenous biosynthesis of lipids (lipogenesis) is a key process throughout the entire life but especially during brain and lung growth. Adequate synthesis of pulmonary surfactant lipids is indispensable for life. With this study, we report the use of deuterium-depleted water (DDW), suitable for human consumption, as metabolic precursor for lipogenesis. We studied 13 adult rabbits for 5 days. Four rabbits drank tap water (TW) and served as controls; in four animals, DDW was substituted to drinking water, whereas five drank deuterium-enriched water (DEW). After 5 days, a blood sample and a bronchoalveolar lavage (BAL) sample were collected. The 2H/1H (δ2H) of BAL palmitic acid (PA) desaturated phosphatidylcholine (DSPC), the major phospholipid of pulmonary surfactant, and of plasma water was determined by high-resolution mass spectrometry. We found that the δ2H values of DDW, DEW and TW were −984 ± 2‰, +757 ± 2‰ and −58 ± 1‰, respectively. After 5 days, plasma water values were −467 ± 87‰, +377 ± 56‰ and −53 ± 6‰, and BAL DSPC-PA was −401 ± 27‰, −96 ± 38‰ and −249 ± 9‰ in the DDW, DEW and TW, respectively. With this preliminary study, we demonstrated the feasibility of using DDW to label pulmonary surfactant lipids. This novel approach can be used in animals and in humans, and we speculate that it could be associated with more favourable study compliance than DEW in human studies. 相似文献
946.
Samuel Boissière Chiara Camere Alessandra Sarti 《Journal of Pure and Applied Algebra》2019,223(3):1123-1138
We describe periods of irreducible holomorphic symplectic manifolds of -type with a non-symplectic automorphism of prime order . These turn out to lie on complex ball quotients and we are able to give a precise characterization of when the period map is bijective by introducing the notion of -generality. 相似文献
947.
948.
Qian Xu Sigen A Manon Venet Yongsheng Gao Dezhong Zhou Wei Wang Ming Zeng Chiara Rotella Xiaolin Li Xi Wang Jing Lyu Brian J. Rodriguez Wenxin Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10726-10730
Further to conventional linear, branched, crosslinked, and dendritic polymers, single chain cyclized/knotted polymers (SCKPs) have emerged as a new class of polymer structure with unique properties. Herein, the development of bacteria‐resistant SCKPs is reported and the effect of this structure on the resistance of polymer materials to bacteria is investigated. Four SCKPs were synthesized by reversible addition fragmentation chain transfer (RAFT) homopolymerization of multivinyl monomers (MVMs) and then crosslinked by UV light to form SCKP films. Regardless of MVM type used, the resulting SCKP films showed much higher resistance to bacteria, and up to 75 % less bacterial attachment and biofilm formation, in comparison with the corresponding non‐SCKP films. This is due to the altered surface morphology and hydrophobicity of the SCKP films. These results highlight the critical role of the SCKP structure in enhancing the resistance of polymeric materials to bacteria. 相似文献
949.
Dr. Francesca Nerattini Dr. Matteo Figliuzzi Dr. Chiara Cardelli Dr. Luca Tubiana Dr. Valentino Bianco Prof. Christoph Dellago Dr. Ivan Coluzza 《Chemphyschem》2020,21(4):335-347
Protein sequence stores the information relative to both functionality and stability, thus making it difficult to disentangle the two contributions. However, the identification of critical residues for function and stability has important implications for the mapping of the proteome interactions, as well as for many pharmaceutical applications, e. g. the identification of ligand binding regions for targeted pharmaceutical protein design. In this work, we propose a computational method to identify critical residues for protein functionality and stability and to further categorise them in strictly functional, structural and intermediate. We evaluate single site conservation and use Direct Coupling Analysis (DCA) to identify co-evolved residues both in natural and artificial evolution processes. We reproduce artificial evolution using protein design and base our approach on the hypothesis that artificial evolution in the absence of any functional constraint would exclusively lead to site conservation and co-evolution events of the structural type. Conversely, natural evolution intrinsically embeds both functional and structural information. By comparing the lists of conserved and co-evolved residues, outcomes of the analysis on natural and artificial evolution, we identify the functional residues without the need of any a priori knowledge of the biological role of the analysed protein. 相似文献
950.
Marine Cotte Victor Gonzalez Frederik Vanmeert Letizia Monico Catherine Dejoie Manfred Burghammer Loïc Huder Wout de Nolf Stuart Fisher Ida Fazlic Christelle Chauffeton Gilles Wallez Núria Jimnez Francesc Albert-Tortosa Nati Salvad Elena Possenti Chiara Colombo Marta Ghirardello Daniela Comelli Ermanno Avranovich Clerici Riccardo Vivani Aldo Romani Claudio Costantino Koen Janssens Yoko Taniguchi Joanne McCarthy Harald Reichert Jean Susini 《Molecules (Basel, Switzerland)》2022,27(6)
The European Synchrotron Radiation Facility (ESRF) has recently commissioned the new Extremely Brilliant Source (EBS). The gain in brightness as well as the continuous development of beamline instruments boosts the beamline performances, in particular in terms of accelerated data acquisition. This has motivated the development of new access modes as an alternative to standard proposals for access to beamtime, in particular via the “block allocation group” (BAG) mode. Here, we present the recently implemented “historical materials BAG”: a community proposal giving to 10 European institutes the opportunity for guaranteed beamtime at two X-ray powder diffraction (XRPD) beamlines—ID13, for 2D high lateral resolution XRPD mapping, and ID22 for high angular resolution XRPD bulk analyses—with a particular focus on applications to cultural heritage. The capabilities offered by these instruments, the specific hardware and software developments to facilitate and speed-up data acquisition and data processing are detailed, and the first results from this new access are illustrated with recent applications to pigments, paintings, ceramics and wood. 相似文献