全文获取类型
收费全文 | 36718篇 |
免费 | 6517篇 |
国内免费 | 4264篇 |
专业分类
化学 | 25249篇 |
晶体学 | 477篇 |
力学 | 2424篇 |
综合类 | 295篇 |
数学 | 4429篇 |
物理学 | 14625篇 |
出版年
2024年 | 35篇 |
2023年 | 760篇 |
2022年 | 814篇 |
2021年 | 1102篇 |
2020年 | 1475篇 |
2019年 | 1383篇 |
2018年 | 1231篇 |
2017年 | 1139篇 |
2016年 | 1725篇 |
2015年 | 1689篇 |
2014年 | 2073篇 |
2013年 | 2617篇 |
2012年 | 3214篇 |
2011年 | 3404篇 |
2010年 | 2327篇 |
2009年 | 2294篇 |
2008年 | 2492篇 |
2007年 | 2238篇 |
2006年 | 2140篇 |
2005年 | 1657篇 |
2004年 | 1326篇 |
2003年 | 1086篇 |
2002年 | 975篇 |
2001年 | 804篇 |
2000年 | 829篇 |
1999年 | 789篇 |
1998年 | 704篇 |
1997年 | 666篇 |
1996年 | 675篇 |
1995年 | 611篇 |
1994年 | 532篇 |
1993年 | 428篇 |
1992年 | 423篇 |
1991年 | 324篇 |
1990年 | 300篇 |
1989年 | 237篇 |
1988年 | 203篇 |
1987年 | 171篇 |
1986年 | 153篇 |
1985年 | 152篇 |
1984年 | 103篇 |
1983年 | 70篇 |
1982年 | 60篇 |
1981年 | 36篇 |
1980年 | 16篇 |
1979年 | 10篇 |
1977年 | 2篇 |
1971年 | 1篇 |
1959年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Hierarchically Designed Three‐Dimensional Macro/Mesoporous Carbon Frameworks for Advanced Electrochemical Capacitance Storage 下载免费PDF全文
Yanbing Yang Dr. Peixu Li Shiting Wu Xinyang Li Enzheng Shi Qicang Shen Prof. Dehai Wu Wenjing Xu Prof. Anyuan Cao Prof. Quan Yuan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(16):6157-6164
Mesoporous carbon (m‐C) has potential applications as porous electrodes for electrochemical energy storage, but its applications have been severely limited by the inherent fragility and low electrical conductivity. A rational strategy is presented to construct m‐C into hierarchical porous structures with high flexibility by using a carbon nanotube (CNT) sponge as a three‐dimensional template, and grafting Pt nanoparticles at the m‐C surface. This method involves several controllable steps including solution deposition of a mesoporous silica (m‐SiO2) layer onto CNTs, chemical vapor deposition of acetylene, and etching of m‐SiO2, resulting in a CNT@m‐C core–shell or a CNT@m‐C@Pt core–shell hybrid structure after Pt adsorption. The underlying CNT network provides a robust yet flexible support and a high electrical conductivity, whereas the m‐C provides large surface area, and the Pt nanoparticles improves interfacial electron and ion diffusion. Consequently, specific capacitances of 203 and 311 F g?1 have been achieved in these CNT@m‐C and CNT@m‐C@Pt sponges as supercapacitor electrodes, respectively, which can retain 96 % of original capacitance under large degree compression. 相似文献
82.
83.
Preparation and characterization of covalently bonded PVA/Laponite/HAPI nanocomposite multilayer freestanding films by layer‐by‐layer assembly 下载免费PDF全文
Wenchen Ren Ronglan Wu Pingping Guo Jinlong Zhu Huili Li Shimei Xu Jide Wang 《Journal of Polymer Science.Polymer Physics》2015,53(8):545-551
The layer‐by‐layer (LBL) assembly technique is an attractive method to make functional multilayer thin films and has been applied to fabricate a wide range of materials. LBL materials could improve optical transmittance and mechanical properties if the film components were covalently bonded. Covalently bonded nanocomposite multilayer films were prepared by employing hydrophilic aliphatic polyisocyanate (HAPI) as the reactive component, to react with Laponite and polyvinyl alcohol (PVA). FT‐IR spectra suggested that HAPI reacted with Laponite and PVA at ambient temperature rapidly. Ellipsometry measurement showed that the film thickness was in linear growth. The influences of HAPI on the optical, mechanical and thermal properties of the films were investigated by UV‐Vis spectroscopy, tensile stress measurement, DSC and TGA. The obtained results showed that the optical transmittance and mechanical strength were enhanced when the film components were covalently bonded by HAPI. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 545–551 相似文献
84.
85.
86.
87.
88.
89.
Determination of corilagin in rat plasma using a liquid chromatography–electrospray ionization tandem mass spectrometric method 下载免费PDF全文
Qian Qian Chen Jianru Guo Hongyan Fan Caiyun Wang Fengguo Xu Wei Zhang 《Biomedical chromatography : BMC》2015,29(10):1553-1558
A sensitive and simple liquid chromatography–tandem mass spectrometric (HPLC‐MS/MS) method for the determination of corilagin in rat plasma has been developed. Samples were prepared with protein precipitation method and analyzed with a triple quadrupole tandem mass spectrometer. We employed negative electrospray ionization as the ionization source and the analytes were detected in multiple reaction monitoring mode. Separation was achieved on a C8 column eluted with mobile phase consisting of methanol–0.1% formic acid in a gradient mode at the flow rate of 0.3 mL/min. The total run time was 7.0 min.This method was proved to have good linearity in the concentration range of 2.5–1000.0 ng/mL. The lower limit of quantification of corilagin was 2.5 ng/mL. The intra‐ and inter‐day relative standard deviationa across three validation runs for four concentration levels were both <9.8%. The relative error was within ±6.0%. This assay offers advantages in terms of expediency and suitability for the analysis of corilagin in rat plasma. The practical utility of this new HPLC‐MS/MS method was confirmed in pilot plasma concentration studies in rats following oral administration. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
90.