全文获取类型
收费全文 | 242篇 |
免费 | 12篇 |
专业分类
化学 | 105篇 |
晶体学 | 5篇 |
力学 | 18篇 |
数学 | 62篇 |
物理学 | 64篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 17篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 21篇 |
2012年 | 15篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1921年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有254条查询结果,搜索用时 15 毫秒
1.
Bayer Arend Lahoz Martí Macrì Emanuele Nuer Howard Perry Alexander Stellari Paolo 《Publications Mathématiques de L'IHéS》2021,133(1):157-325
Publications mathématiques de l'IHÉS - We develop a theory of Bridgeland stability conditions and moduli spaces of semistable objects for a family of varieties. Our approach is based... 相似文献
2.
Dr. Lara Martinez-Fernandez Dr. Krishna Gavvala Dr. Rajans Sharma Prof. Pascal Didier Dr. Ludovic Richert Dr. Javier Segarra Martì Dr. Mattia Mori Prof. Yves Mely Dr. Roberto Improta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(30):7375-7386
Thienoguanosine (thG) is an isomorphic analogue of guanosine with promising potentialities as fluorescent DNA label. As a free probe in protic solvents, thG exists in two tautomeric forms, identified as the H1, being the only one observed in nonprotic solvents, and H3 keto–amino tautomers. We herein investigate the photophysics of thG in solvents of different polarity, from water to dioxane, by combining time-resolved fluorescence with PCM/TD-DFT and CASSCF calculations. Fluorescence lifetimes of 14.5–20.5 and 7–13 ns were observed for the H1 and H3 tautomers, respectively, in the tested solvents. In methanol and ethanol, an additional fluorescent decay lifetime (≈3 ns) at the blue emission side (λ≈430 nm) as well as a 0.5 ns component with negative amplitude at the red edge of the spectrum, typical of an excited-state reaction, were observed. Our computational analysis explains the solvent effects observed on the tautomeric equilibrium. The main radiative and nonradiative deactivation routes have been mapped by PCM/TD-DFT calculations in solution and CASSCF in the gas phase. The most easily accessible conical intersection, involving an out-of plane motion of the sulfur atom in the five-membered ring of thG, is separated by a sizeable energy barrier (≥0.4 eV) from the minimum of the spectroscopic state, which explains the large experimental fluorescence quantum yield. 相似文献
3.
4.
5.
Andrea Liscio Massimo Bonini Emanuele Treossi Emanuele Orgiu Marcel Kastler Florian Dötz Vincenzo Palermo Paolo Samorì 《Journal of Polymer Science.Polymer Physics》2012,50(9):642-649
A prototypical semiconducting bicomponent system consisting of a conjugated polymer, that is, poly(3‐hexylthiophene) (P3HT), blended with a small thiophene containing conjugated molecule, that is, an alkyl‐substituted bisphenyl‐bithiophene [phenylene–thiophene–thiophene–phenylene (PTTP)], has been used as an electroactive active layer in field‐effect transistors (FETs). The self‐assembly of this bicomponent system at surfaces has been studied at different length scales, from the nanoscale to the macroscale, and compared with the behavior of monocomponent films of PTTP and P3HT. The correlation between morphology and electric properties of the semiconducting material is explored by fabricating prototypes of FETs varying the relative concentrations of the two‐component blend. The maximum charge carrier mobility value, achieved with a few percent of PTTP component, is not simply due to a uniform dispersion of the molecules in the polymer matrix, but rather to the generation of very long percolation paths, whose composition and electrical properties can be tuned with the PTTP concentration. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
6.
Marcello Bernardara Emanuele Macrì Sukhendu Mehrotra Paolo Stellari 《Advances in Mathematics》2012,229(2):770-803
We prove a categorical version of the Torelli theorem for cubic threefolds. More precisely, we show that the non-trivial part of a semi-orthogonal decomposition of the derived category of a cubic threefold characterizes its isomorphism class. 相似文献
7.
Sheng Yang Antonio Gaetano Ricciardulli Dr. Shaohua Liu Dr. Renhao Dong Dr. Martin R. Lohe Alfons Becker Marco A. Squillaci Prof. Paolo Samorì Prof. Klaus Müllen Prof. Xinliang Feng 《Angewandte Chemie (International ed. in English)》2017,56(23):6669-6675
To bridge the gap between laboratory-scale studies and commercial applications, mass production of high quality graphene is essential. A scalable exfoliation strategy towards the production of graphene sheets is presented that has excellent yield (ca. 75 %, 1–3 layers), low defect density (a C/O ratio of 21.2), great solution-processability, and outstanding electronic properties (a hole mobility of 430 cm2 V−1 s−1). By applying alternating currents, dual exfoliation at both graphite electrodes enables a high production rate exceeding 20 g h−1 in laboratory tests. As a cathode material for lithium storage, graphene-wrapped LiFePO4 particles deliver a high capacity of 167 mAh g−1 at 1 C rate after 500 cycles. 相似文献
8.
Anise Akhundi Elisa I. García-López Giuseppe Marcì Aziz Habibi-Yangjeh Leonardo Palmisano 《Research on Chemical Intermediates》2017,43(9):5153-5168
Carbon nitride photocatalysts have been prepared by different methodologies, such as chemical ultrasonic irradiation (sonochemical treatment), hydrothermal and ball milling and thermoexfoliation, and have been used for the selective oxidation of 5-hydroxymethyl-2-furaldehyde (HMF) to form 2,5-furandicarboxyaldehyde (FDC) in water suspension both under UV and natural solar irradiation. The physico-chemical features of the photocatalysts have been studied by X-ray diffraction, infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, and specific surface area measurements. The results indicate that exfoliation of carbon nitrides can increase the conversion of HMF and the selectivity to FDC. In particular, samples exfoliated by both thermal and acidic ultrasonic irradiation treatments showed the best photocatalytic performance. 相似文献
9.
Angela Giorgia Potortì Alessia Tropea Vito Pellizzeri Asma Belfita Giacomo Dugo 《Natural product research》2020,34(1):167-171
AbstractSpices and aromatic herbs can be contaminated with mycotoxins, since of their preharvest, postharvest, and storage conditions. In this study, 112 samples of different spices and aromatic herbs were evaluated for their mycotoxins content by HPLC-MS/MS in order to highlight their possible risk linked with human use. The results showed that mycotoxins were occasionally detected only in samples of coriander, laurel, mint, rosemary, and verbena. In both geographical origins a different contamination was detected. Among the investigated mycotoxins, AFB2, AFG1, AFG2, T2 and HT2 were detected, whereas none of the samples contained AFB1 and FB1. The co-occurrence of two toxins were observed for some samples of rosemary and verbena. This study indicates that it is essential minimize the toxins in agriculture, industry, and food-product manufacturing for the consumer health protection. 相似文献