全文获取类型
收费全文 | 2733篇 |
免费 | 129篇 |
国内免费 | 15篇 |
专业分类
化学 | 1981篇 |
晶体学 | 13篇 |
力学 | 80篇 |
数学 | 407篇 |
物理学 | 396篇 |
出版年
2023年 | 24篇 |
2022年 | 49篇 |
2021年 | 61篇 |
2020年 | 70篇 |
2019年 | 56篇 |
2018年 | 66篇 |
2017年 | 59篇 |
2016年 | 111篇 |
2015年 | 97篇 |
2014年 | 117篇 |
2013年 | 204篇 |
2012年 | 226篇 |
2011年 | 224篇 |
2010年 | 142篇 |
2009年 | 116篇 |
2008年 | 184篇 |
2007年 | 175篇 |
2006年 | 127篇 |
2005年 | 121篇 |
2004年 | 132篇 |
2003年 | 89篇 |
2002年 | 68篇 |
2001年 | 27篇 |
2000年 | 25篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 22篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 15篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1973年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有2877条查询结果,搜索用时 15 毫秒
151.
Young-Hun Cho Jae-Gyoung Seong Jae-Hyun Noh Da-Young Kim Yong-Sik Chung Tae Hoon Ko Byoung-Suhk Kim 《Molecules (Basel, Switzerland)》2020,25(24)
In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO2-coated and Fe2O3-coated carbon fibers were used as the cathode and the anode materials, respectively. Herein, the nanostructured CoMnO2 were directly deposited onto carbon fibers by a chemical oxidation route without high temperature treatment in presence of ammonium persulfate (APS) as an oxidizing agent. FE-SEM analysis confirmed that the CoMnO2-coated carbon fiber electrode exhibited the porous hierarchical interconnected nanosheet structures, depending on the added amount of APS, and Fe2O3-coated carbon fiber electrode showed a uniform distribution of porous Fe2O3 nanorods over the surface of carbon fibers. The electrochemical properties of the CoMnO2-coated carbon fiber with the concentration of 6 mmol APS presented the enhanced electrochemical activity, probably due to its porous morphologies and good conductivity. Further, to reduce the interfacial contact resistance as well as improve the adhesion between transition metal nanostructures and carbon fibers, the carbon fibers were pre-coated with the Ni layer as a seed layer using an electrochemical deposition method. The fabricated ASC device delivered a specific capacitance of 221 F g−1 at 0.7 A g−1 and good rate capability of 34.8% at 4.9 A g−1. Moreover, the wire-type device displayed the superior energy density of 60.2 Wh kg−1 at a power density of 490 W kg−1 and excellent capacitance retention of 95% up to 3000 charge/discharge cycles. 相似文献
152.
Siqueira Iolanda Scheibe de Dweck Jo Toledo Filho Romildo Dias 《Journal of Thermal Analysis and Calorimetry》2020,142(4):1413-1428
Journal of Thermal Analysis and Calorimetry - The interest in the use of cellulose fibers of increasingly smaller sizes in cementitious materials has increased in recent years. This paper brings... 相似文献
153.
Xinglong Chen Hongil Jo Kang Min Ok 《Angewandte Chemie (International ed. in English)》2020,59(19):7514-7520
To design high‐performance mid‐infrared (mid‐IR) nonlinear optical (NLO) materials, we have focused on the combination of a heavy metal lone pair cation, Pb2+ and mixed oxyhalides. A systematic investigation in PbO‐PbCl2‐PbBr2 system led us to discover the first examples of NLO lead mixed oxyhalides, namely, Pb13O6Cl4Br10, Pb13O6Cl7Br7, and Pb13O6Cl9Br5. All the reported materials have remarkably comprehensive properties including broad IR transparency (up to 14.0 μm), qualified second harmonic generation (SHG) responses (0.6–0.9×AgGaS2), wide band gaps (3.05–3.21 eV), and ease of crystal growth. Interestingly, a centimeter‐sized single crystal (2.9×1.3×0.5 cm3) of Pb13O6Cl9Br5 revealing a wide transparent range (0.384–14.0 μm) and high laser damage threshold (LDT) (14.6×AgGaS2) has been successfully grown in an open system. The study suggests that all the reported mixed oxyhalides are outstanding candidates for mid‐IR NLO materials. 相似文献
154.
155.
Jo?o-Paulo DIAS 《数学年刊B辑(英文版)》2021,42(2):163-172
In this paper, the author studies the local existence of strong solutions and their possible blow-up in time for a quasilinear system describing the interaction of a short wave induced by an electron field with a long wave representing an extension of the motion of the director field in a nematic liquid crystal’s asymptotic model introduced in [Saxton, R. A., Dynamic instability of the liquid crystal director. In: Current Progress in Hyperbolic Systems (Lindquist, W. B., ed.), Contemp. Math., Vol.100, Amer. Math.Soc., Providence, RI, 1989, pp.325–330] and [Hunter, J. K. and Saxton, R. A., Dynamics of director fields, SIAM J. Appl. Math., 51, 1991, 1498–1521] and studied in [Hunter, J. K. and Zheng, Y., On a nonlinear hyperbolic variational equation I, Arch. Rat. Mech. Anal.,129, 1995, 305–353], [Hunter, J. K. and Zheng, Y., On a nonlinear hyperbolic variational equation II, Arch. Rat. Mech. Anal., 129, 1995, 355–383] and in [Zhang, P. and Zheng,Y., On oscillation of an asymptotic equation of a nonlinear variational wave equation,Asymptotic Anal., 18, 1998, 307–327] and, more recently, in [Bressan, A., Zhang, P. and Zheng, Y., Asymptotic variational wave equations, Arch. Rat. Mech. Anal., 183, 2007,163–185]. 相似文献
156.
B. K. Kim K. H. Lee N. J. Jo 《Journal of polymer science. Part A, Polymer chemistry》1996,34(11):2095-2102
Effects of hard segment type, soft segment type, soft segment length, and crystallization at various levels of reactive diluent have been studied in polyurethane acrylates. PTMG–IPDI-based PU acrylates gave better soft segment-hard segment phase separation as compared with PTMG–TDI-based ones. Among PTMG–, PCL–, and PTAd–IPDI-based materials, only PTMG-based one gave clean phase separation, and PTAd-based gave the poorest phase separation. With greater phase separation, higher modulus was obtained. Crystallization of soft segment in PTAd–IPDI-based material gave a significant increase in tensile modulus and elongation at break, with a notable difference in dynamic mechanical properties. © 1996 John Wiley & Sons, Inc. 相似文献
157.
Machado J. A. Tenreiro Rocha-Neves João M. Andrade José P. 《Nonlinear dynamics》2020,101(3):1731-1750
Nonlinear Dynamics - This paper tackles the information of 133 RNA viruses available in public databases under the light of several mathematical and computational tools. First, the formal concepts... 相似文献
158.
João Miller de Melo Henrique Pablo Cañizares Cristina Saez Elisama Vieira dos Santos Manuel Andrés Rodrigo 《Current Opinion in Electrochemistry》2021
Treatment of polluted soil is one of the priorities in the search of a more sustainable planet. Electrochemically assisted soil remediation has been considered a good option for removing organic contaminants contained in soil, including the removal of volatile organic compounds, associated with gaseous streams produced during the treatment. Also, recently, electrochemical gas treatment technologies have been appointed as promising for the treatment of volatile organic compounds. In this work, we review the current opinion about the most recent studies in both areas. The first section focuses on the production of gaseous compounds during soil remediation by conventional and electrochemical systems. The second section describes the recent progress in the integration of adsorption and absorption with electrochemical processes. Finally, we discuss the holistic application of assisted electrochemical technologies in soil remediation, considering also emerging processes recently published in the literature. 相似文献
159.
Dr. Tomoya Oshikiri Haruki Jo Dr. Xu Shi Prof. Hiroaki Misawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(24):e202200288
Hot-hole injection from plasmonic metal nanoparticles to the valence band of p-type semiconductors and reduction by hot electrons should be improved for efficient and tuneable reduction to obtain beneficial chemical compounds. We employed the concept of modal strong coupling between plasmons and a Fabry-Pérot (FP) nanocavity to enhance the hot-hole injection efficiency. We fabricated a photocathode composed of gold nanoparticles (Au−NPs), p-type nickel oxide (NiO), and a platinum film (Pt film) (ANP). The ANP structure absorbs visible light over a broad wavelength range from 500 nm to 850 nm via hybrid modes based on the modal strong coupling between the plasmons of Au−NPs and the FP nanocavity of NiO on a Pt film. All wavelength regions of the hybrid modes of the modal strong coupling system promoted hot-hole injection from the Au−NPs to NiO and proton/water reduction by hot electrons. The incident photon-to-current efficiency based on H2 evolution through water/proton reduction by hot electrons reached 0.2 % at 650 nm and 0.04 % at 800 nm. 相似文献
160.
Marcus V. P. dos Santos Eduardo C. Aguiar João Bosco P. da Silva Ricardo L. Longo 《Journal of computational chemistry》2013,34(8):611-621
A new approach Procedure for Investigating Categories of Vibrations (PICVib) for estimating vibrational frequencies of selected modes using only the structure and energy calculations at a more demanding computational level is presented and explored. The PICVib has an excellent performance at only a small fraction of the computational demand required for a complete analytical calculation. The errors are smaller than ca. 0.5% when DFT functionals are combined with high level ab initio methods. The approach is general because it can use any quantum chemical program and electronic structure method. It is very robust because it was validated for a wide range of frequency values (ca. 20–4800 cm–1) and systems: XH3 (D3h) with X = B, Al, Ga, N, P, As, O, S, and Se, YH4 (D4h) with Y = C, Si, and Ge, conformers of RDX, SN2 and E2 reactions, [W(dppe)2(NNC5H10)] complex, carbon nanotubes, and hydrogen‐bonded complexes including guanine‐cytosine pair. © 2012 Wiley Periodicals, Inc. 相似文献