全文获取类型
收费全文 | 482篇 |
免费 | 169篇 |
国内免费 | 93篇 |
专业分类
化学 | 375篇 |
晶体学 | 26篇 |
力学 | 13篇 |
综合类 | 5篇 |
数学 | 18篇 |
物理学 | 307篇 |
出版年
2024年 | 3篇 |
2023年 | 2篇 |
2022年 | 28篇 |
2021年 | 29篇 |
2020年 | 24篇 |
2019年 | 24篇 |
2018年 | 21篇 |
2017年 | 37篇 |
2016年 | 38篇 |
2015年 | 37篇 |
2014年 | 47篇 |
2013年 | 67篇 |
2012年 | 52篇 |
2011年 | 64篇 |
2010年 | 36篇 |
2009年 | 33篇 |
2008年 | 30篇 |
2007年 | 37篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 19篇 |
2003年 | 17篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 3篇 |
排序方式: 共有744条查询结果,搜索用时 71 毫秒
51.
黄铜矿铜铟硒化合物CuInSe2及其与硫或嫁的合金CuIn(Se,S)2或CuInGa(Se,S)2,即所说的CIGS,已通过20%的实验室规模器件光电转换效率展示了其地面光伏应用的巨大潜力。为了减少初始资金成本,提高材料利用率,科研工作者们已经尝试了许多努力通过非真空制程沉积CIGS。这些制程包括电镀工艺,基于颗粒(浆或纳米颗粒)的制程和基于分子量级前趋体的制程。原则上,分子量级前趋体可以使组分元素达到充分混合,可以最大程度地实现组份在基板不同区域的均一分布。这对于一个复杂的涉及到五个主要元素的化合物系统尤为重要。从这个角度来看,分子前趋体的方法具有大面积均匀沉积铜铟镓硒的巨大潜力。这篇综述将着重讨论使用分子前趋体沉积铜铟镓硒制程的最新发展。 相似文献
52.
基于菲聂尔透镜的聚焦太阳能PV/T 系统热电性能研究 总被引:1,自引:0,他引:1
本文建立了基于菲涅尔透镜的聚焦型PV/T热电联产系统的一维稳态传热模型,对六种不同结构的PV/T系统的热、电效率和(火用)效率进行了计算,利用(火用)效率作为评价标准对六种系统进行了比较.分析表明采用聚焦型PV/T系统,在牺牲少量发电效率的基础上,可以获得具有一定温度的热能;增添玻璃盖板虽然能够减少热损失,但同时使得系统的光学效率降低,减少电池上的能量密度,反而使得系统的(火用)效率降低1%;环境恶劣的情况下,应将集热管外加保温腔体,透镜起到盖板和聚光器的双重作用,在不损失发电量的同时可以提高系统的热效率. 相似文献
53.
对于掺铁铌酸锂晶体中不同全息记录配置下的磁光折变效应做了比较系统的理论分析,给出了铌酸锂晶体所有的磁光生伏打非零张量元. 详细计算并给出了不同全息纪录配置下的所有体光生伏打、磁光生伏打电流的解析形式. 理论结果表明,由于磁光生伏打效应引起了光激发电流的变化,所以对于每种配置全息光栅的衍射效率都会受到外加磁场的影响;对于不同的全息记录配置,磁场对铌酸锂晶体光折变非线性性质的影响也不同.讨论了一种确定特定张量元的方法.
关键词:
磁光生伏打
磁光折变效应
光生伏打 相似文献
54.
55.
56.
A plasmonic multilayer structure (PMS) is proposed for photovoltaic cells with an ultrathin active layer that is 30 nm amorphous
Si (α-Si). The optical properties of the PMS are analyzed by rigorous coupled-wave analysis (RCWA) and finite-difference time-domain
(FDTD) method. Using the PMS, the incident light can be trapped into localized surface plasmon (LSP) and then the localized
surface plasmon induces the surface plasmon (SP) that propagates transversely within the α-Si layer. Compared with the indium tin oxide (ITO)/α-Si/Ag structure, the photon number absorbed by PMS increase 28.7% while a normal incident transverse magnetic (TM) polarization
wave is applied. 相似文献
57.
58.
Ming Liu Yafei Wang Zhiyong Zhang Jianming Li Yu Liu Hua Tan Meijun Ni Gangtie Lei Meixiang Zhu Weiguo Zhu 《Journal of polymer science. Part A, Polymer chemistry》2011,49(17):3874-3881
To exploit an effective way to improve polymeric photovoltaic performance, a series of dithiophene‐benzothiadiazole‐alt‐fluorene copolymers containing carbazole groups at C‐9 positions of the alternating fluorene units (PFO‐FCz‐DBT) were synthesized and characterized. The effect of the carbazole groups on the optophysical, electrochemical, and photovoltaic properties of these copolymers was investigated. By comparison, this type of copolymers with carbazole units exhibited significantly improved photovoltaic properties than poly(2,7‐(9,9‐dioctyl‐fluorene)‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole) (PFO‐DBT) in the bulk heterojunction solar cells. A maximum power‐conversion efficiency (PCE) of 2.41% and a highest short‐circuit current density (Jsc) of 9.68 mA cm?2 were obtained for the PFO‐FCz‐DBT30, which are about two times higher than the corresponding levels for the PFO‐DBT30. This work demonstrated that introducing a hole‐transporting carbazole unit into copolymer is a simple and effective method to improve the Jsc and PCE. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
59.
Qiang Peng Xiangju Liu Yuancheng Qin Dan Zhou Jun Xu 《Journal of polymer science. Part A, Polymer chemistry》2011,49(20):4458-4467
A new series of low‐bandgap copolymers based on electron‐accepting thieno[3,4‐b]pyrazine (TPZ) and different electron‐donating aza‐heteroaromatic units, such as carbazole (CZ), dithieno[3,2‐b:2′,3′‐d]pyrrole (TPR) and dithieno[3,2‐b:2′,3′‐e]pyridine (TPY), have been synthesized by Suzuki or Stille coupling polymerization. The resulting copolymers were characterized by NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. UV–vis absorption and cyclic voltammetry measurements show that TPZ‐based copolymer with TPR has the best absorption due to the strongest intramolecular charge transfer effect and smallest bandgap. The basic electronic structure of D‐A model compounds of these copolymers were also studied by density functional theory (DFT) calculations. The conclusion of calculation agreed also well with the experimental results. The polymer solar cells (PSCs) based on these copolymers were fabricated with a typical structure of ITO/PEDOT:PSS/copolymer:PC71BM/Ca/Al under the illumination of AM 1.5G, 100 mW cm?2. The performance results showed that TPZ‐based copolymer with TPR donor segments showed highest efficiency of 1.55% due to enhanced short‐circuit current density. The present results indicate that good electronic, optical, and photovoltaic properties of TPZ‐based copolymers can be achieved by just fine‐tuning the structures of aza‐heteroaromatic donor segments for their application in PSCs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
60.
Zhijie Gu Tatsuya Kanto Kousuke Tsuchiya Takeshi Shimomura Kenji Ogino 《Journal of polymer science. Part A, Polymer chemistry》2011,49(12):2645-2652
Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献