全文获取类型
收费全文 | 3876篇 |
免费 | 177篇 |
国内免费 | 15篇 |
专业分类
化学 | 2568篇 |
晶体学 | 41篇 |
力学 | 63篇 |
综合类 | 1篇 |
数学 | 440篇 |
物理学 | 955篇 |
出版年
2023年 | 40篇 |
2022年 | 85篇 |
2021年 | 113篇 |
2020年 | 101篇 |
2019年 | 116篇 |
2018年 | 89篇 |
2017年 | 97篇 |
2016年 | 161篇 |
2015年 | 119篇 |
2014年 | 125篇 |
2013年 | 229篇 |
2012年 | 254篇 |
2011年 | 315篇 |
2010年 | 193篇 |
2009年 | 201篇 |
2008年 | 278篇 |
2007年 | 249篇 |
2006年 | 205篇 |
2005年 | 180篇 |
2004年 | 169篇 |
2003年 | 115篇 |
2002年 | 89篇 |
2001年 | 63篇 |
2000年 | 72篇 |
1999年 | 47篇 |
1998年 | 28篇 |
1997年 | 29篇 |
1996年 | 32篇 |
1995年 | 30篇 |
1994年 | 23篇 |
1993年 | 29篇 |
1992年 | 32篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1972年 | 4篇 |
1968年 | 3篇 |
排序方式: 共有4068条查询结果,搜索用时 31 毫秒
961.
Interfacial properties and thermal stability of modified poly(m‐phenylene isophthalamide) thin films
Sandra Cruz dos Santos Lara Fernandes Loguercio Diogo Silva Corrêa Michael Ramos Nunes Marcos Antônio Villetti Irene Teresinha Santos Garcia 《Surface and interface analysis : SIA》2013,45(4):837-843
Poly(m‐phenylene isophthalamide) (PMIA) is a resistant to high temperatures and chemically stable engineering material. The application as coatings and membranes, however, is limited by its poor interaction with other materials. In this report, we describe the molecular modification of PMIA through reaction with dimsyl sodium and 2‐iodine‐1‐ethanol. The substitution of 58% of amide hydrogen by ethanol (etOH) groups produces a material (MPMIA) able to develop regularly structured films on silicon substrate. The morphology of the films is dependent on the ionic strength of the precursory solution. MPMIA starts a degradation process by losing the etOH group. MPMIA has a better affinity with poly(p‐cresolformaldehyde) than with a pristine one, increasing the range of composition in which thermal stability and miscibility are observed. Thin films of these blends have different morphologies that vary from nanometric porous to two‐phase microstructured grains, according to the composition. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
962.
Ana Sánchez-Grande Dr. José I. Urgel Aleš Cahlík Dr. José Santos Shayan Edalatmanesh Eider Rodríguez-Sánchez Dr. Koen Lauwaet Dr. Pingo Mutombo Prof. Dana Nachtigallová Reed Nieman Prof. Hans Lischka Dr. Bruno de la Torre Prof. Rodolfo Miranda Dr. Oliver Gröning Prof. Nazario Martín Prof. Pavel Jelínek Prof. David Écija 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(40):17747-17752
We report on the synthesis and characterization of atomically precise one-dimensional diradical peripentacene polymers on a Au(111) surface. By means of high-resolution scanning probe microscopy complemented by theoretical simulations, we provide evidence of their magnetic properties, which arise from the presence of two unpaired spins at their termini. Additionally, we probe a transition of their magnetic properties related to the length of the polymer. Peripentacene dimers exhibit an antiferromagnetic (S=0) singlet ground state. They are characterized by singlet–triplet spin-flip inelastic excitations with an effective exchange coupling (Jeff) of 2.5 meV, whereas trimers and longer peripentacene polymers reveal a paramagnetic nature and feature Kondo fingerprints at each terminus due to the unpaired spin. Our work provides access to the precise fabrication of polymers featuring diradical character which are potentially useful in carbon-based optoelectronics and spintronics. 相似文献
963.
Santos Lidya B. Striebeck Maria V. Crespi Marisa S. Ribeiro Clovis A. De Julio Marcelo 《Journal of Thermal Analysis and Calorimetry》2015,122(1):21-32
Journal of Thermal Analysis and Calorimetry - Recently, biochar was introduced as a bioadsorbent material to remove various contaminants in effluents, such as pigments, dyes, heavy metals,... 相似文献
964.
Influence of Plasticizers on the Electromechanical Behavior of a P(VDF‐TrFE‐CTFE) Terpolymer: Toward a High Performance of Electrostrictive Blends
下载免费PDF全文
![点击此处可从《Journal of Polymer Science.Polymer Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nellie Della Schiava Minh‐Quyen Le Jeremy Galineau Fabrice Domingues Dos Santos Pierre‐Jean Cottinet Jean‐Fabien Capsal 《Journal of Polymer Science.Polymer Physics》2017,55(4):355-369
This work aims at providing a complete analysis of the effect of plasticizers on the electrostrictive terpolymer performance. To achieve this, several plasticizing agents such as 2‐ethylhexyl phtalate (DEHP), diisononyl phtalate (DINP), and palamoll 652 have been incorporated in the polymer matrix. Experimental results demonstrate that the proposed novel materials exhibited excellent electromechanical enhancement in terms of transverse strain and mechanical energy density under a moderate electric field, which is definitively critical in recent microscale actuation. Another objective of this article was to explore material characteristics as a function of the DINP content, and it was found that the plasticizer weigh fraction was the key parameter determining performance of the modified fluorinate terpolymer blends. Accordingly, it was revealed that high performance flexible actuators can be achieved merely by employing a simple and cheap plasticizer, thus making it possible to overcome the current technological barrier of conventional electroactive polymers that suffer from the high applied electric field usually required to reach sufficient strain. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 355–369 相似文献
965.
Anne Sophie Voisin-Chiret Grégory Burzicki Serge Perato Marcella De Giorgi Carlo Franchini Jana Sopková-de Oliveira Santos Sylvain Rault 《Tetrahedron》2012,68(23):4381-4389
Proteins modulate the majority of all biological functions and are composed of highly organized secondary structural elements such as helices, turns, and sheets. Many of these functions are affected by a small number of key structural element, protein–protein interactions. Their mimicry by peptide and non-peptide scaffolds has become a major focus of contemporary research. This paper examines oligomeric system as new foldamers, which either reproduce the local topography of the helix, or project appropriately functionality in a similar manner to residues of an alpha-helix. 相似文献
966.
967.
Dr. Fábio M. F. Santos Zoe Domínguez João P. L. Fernandes Dr. Cátia Parente Carvalho Dr. Daniel Collado Prof. Dr. Ezequiel Pérez-Inestrosa Maria V. Pinto Dr. Adelaide Fernandes Dr. Jesús F. Arteaga Dr. Uwe Pischel Dr. Pedro M. P. Gois 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(62):14064-14069
Boronic acid-derived salicylidenehydrazone complex (BASHY) dyes with a polymethine backbone were designed to yield efficient red-emitting and two-photon absorbing fluorophores that can be used as markers for astrocytes. The dyes are chemically stable in aqueous solution and do not undergo photodecomposition. Their photophysical properties can be electronically fine-tuned and thereby adapted to potentially different imaging situations and requirements. 相似文献
968.
Jos Luis Malvar Juan Luis Santos Julia Martín Irene Aparicio Esteban Alonso 《Molecules (Basel, Switzerland)》2020,25(22)
The release of pharmaceutically active compounds to the soils through the application of sewage sludge and the irrigation with wastewater, or even with surface water, is constant. The adsorption of these compounds onto the soil is one of the key factors affecting their fate in the environment and their potential environmental risks. In this work, the adsorption of carbamazepine (CBZ) and its metabolites, 3-hydroxy-carbamazepine (3OH-CBZ), carbamazepine-10,11-dihydro-10,11-epoxide (EP-CBZ), and 10,11-dihydro-10-hydroxycarbamazepine (10OH-CBZ), in three Mediterranean soils was evaluated using single-solute and four-solute experiments. The highest adsorptions were measured for 3OH-CBZ, followed by CBZ, EP-CBZ, and 10OH-CBZ, in that order. A high influence of the physicochemical characteristics of the compounds, pH, and soil characteristics in the adsorption of the studied compounds was observed and corroborated by the statistical analysis of the results. Moreover, a good fit was observed in the three isotherm models evaluated (linear, Freundlich, and Langmuir) in single-solute experiments (R2 > 0.90). However, a decrease of the measured adsorptions and a worse fit to the isotherm models were observed in the case of multiple-solute experiments. This could be mainly due to the competition established between the studied compounds for the active sites of the soils. 相似文献
969.
970.
Lemos Paulo Vitor França Barbosa Leandro Santos Ramos Ingrid Graça Coelho Rodrigo Estevam Druzian Janice Izabel 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2555-2567
Journal of Thermal Analysis and Calorimetry - The thermal features of potato, banana, corn and cassava starches were correlated with structural properties. These starches were characterized by SEM,... 相似文献