全文获取类型
收费全文 | 109201篇 |
免费 | 7841篇 |
国内免费 | 9489篇 |
专业分类
化学 | 64434篇 |
晶体学 | 1826篇 |
力学 | 6359篇 |
综合类 | 720篇 |
数学 | 13654篇 |
物理学 | 39538篇 |
出版年
2023年 | 814篇 |
2022年 | 1609篇 |
2021年 | 2301篇 |
2020年 | 2676篇 |
2019年 | 2876篇 |
2018年 | 3191篇 |
2017年 | 3353篇 |
2016年 | 3813篇 |
2015年 | 2896篇 |
2014年 | 4141篇 |
2013年 | 5869篇 |
2012年 | 5948篇 |
2011年 | 6420篇 |
2010年 | 5369篇 |
2009年 | 5425篇 |
2008年 | 5710篇 |
2007年 | 5339篇 |
2006年 | 4955篇 |
2005年 | 4296篇 |
2004年 | 3776篇 |
2003年 | 3256篇 |
2002年 | 3375篇 |
2001年 | 3096篇 |
2000年 | 2637篇 |
1999年 | 1932篇 |
1998年 | 1716篇 |
1997年 | 1460篇 |
1996年 | 1394篇 |
1995年 | 1174篇 |
1994年 | 1270篇 |
1993年 | 1215篇 |
1992年 | 1144篇 |
1991年 | 1178篇 |
1990年 | 1188篇 |
1989年 | 1104篇 |
1988年 | 970篇 |
1987年 | 963篇 |
1986年 | 908篇 |
1985年 | 931篇 |
1984年 | 929篇 |
1983年 | 835篇 |
1982年 | 814篇 |
1979年 | 803篇 |
1978年 | 815篇 |
1977年 | 806篇 |
1976年 | 919篇 |
1975年 | 812篇 |
1974年 | 841篇 |
1973年 | 846篇 |
1972年 | 751篇 |
排序方式: 共有10000条查询结果,搜索用时 227 毫秒
51.
Du Yongbo Yu Pengfei Wang Junxiong Zhang Jinping Wang Chang’an Che Defu 《Journal of Thermal Analysis and Calorimetry》2021,143(1):327-334
Journal of Thermal Analysis and Calorimetry - Coal O2/CO2 combustion is a promising carbon capture and storage technology for coal-fired power plant. Char consumption rate prediction is essential... 相似文献
52.
Applied Magnetic Resonance - The suggested approach allowed us to derive analytical expressions for modeling the shape of solid-echo signal and its time evolution for a system of three-spin groups... 相似文献
53.
54.
随着能源紧缺与环境污染问题的日益严重,太阳能的开发利用越来越受到重视,其中非晶硅薄膜太阳能电池由于其制备工艺简单、价格低廉等优点被广泛地研究.为了使非晶硅薄膜太阳能电池得到更好地利用,提高其转换效率和稳定性显得尤为重要.引入复合背电极是提高非晶硅太阳能电池性能的有效手段,其中对GZO/Al复合背电极的研究还未见报道.在该工作中,利用磁控溅射法在非晶硅电池上制备了GZO/Al复合背电极,研究了复合背电极的制备条件及其对非晶硅太阳能电池性能的影响.结果显示,当GZO层的溅射功率为90 W、Al层的溅射功率为90 W时,具有复合背电极的太阳能电池表现出较好的光电转换性能,其短路电流(ISC)、开路电压(VOC)、填充因子(FF)和电池的光电转换效率(η)分别为8.92 mA、1.55 V、54.48;和7.53;.相较于单层Al背电极的太阳能电池,其光电转换效率大幅提高了47.6;(相对效率). 相似文献
55.
Inside Cover: Photoinduced Formation of an Azobenzene‐Based CD‐Active Supramolecular Cyclic Dimer (Chem. Eur. J. 18/2015) 下载免费PDF全文
56.
57.
CongZhan Liu YiFei Zhang XuFang Li XueFeng Lu Zhi Chang ZhengWei Li AiMei Zhang YongJie Jin HuiMing Yu Zhao Zhang MinXue Fu YiBao Chen JianFeng Ji YuPeng Xu JingKang Deng RenCheng Shang GuoQing Liu FangJun Lu ShuangNan Zhang YongWei Dong TiPei Li Mei Wu YanGuo Li HuanYu Wang BoBing Wu YongJie Zhang Zhi Zhang ShaoLin Xiong Yuan Liu Shu Zhang HongWei Liu YiJung Yang Fan Zhang 《中国科学:物理学 力学 天文学(英文版)》2020,(4):20-34
The Insight-Hard X-ray Modulation Telescope(Insight-HXMT) is a broadband X-ray and γ-ray(1-3000 ke V) astronomy satellite. One of its three main telescopes is the High Energy X-ray telescope(HE). The main detector plane of HE comprises 18 Na I(Tl)/Cs I(Na) phoswich detectors, where Na I(Tl) is used as the primary detector to measure ~ 20-250 ke V photons incident from the field of view(FOV) defined by collimators, and Cs I(Na) is used as the active shielding detector to Na I(Tl) by pulse shape discrimination. Additionally, Cs I(Na) is used as an omnidirectional γ-ray monitor. The HE collimators have a diverse FOV,i.e. 1.1°×5.7°(15 units), 5.7°×5.7°(2 units), and blocked(1 unit). Therefore, the combined FOV of HE is approximately5.7°×5.7°. Each HE detector has a diameter of 190 mm resulting in a total geometrical area of approximately 5100 cm2, and the energy resolution is ~15% at 60 ke V. For each recorded X-ray event by HE, the timing accuracy is less than 10 μs and the deadtime is less than 10 μs. HE is used for observing spectra and temporal variability of X-ray sources in the 20-250 ke V band either by pointing observations for known sources or scanning observations to unveil new sources. Additionally, HE is used for monitoring the γ-ray burst in 0.2-3 Me V band. This paper not only presents the design and performance of HE instruments but also reports results of the on-ground calibration experiments. 相似文献
58.
As a new type of quantum dots (QDs), hexagonal boron nitride quantum dots (BNQDs) exhibit promising potential in the applications of disease diagnosis, fluorescence imaging, biosensing, metal ion detection, and so on, because of their remarkable chemical stability, excellent biocompatibility, low cytotoxicity, and outstanding photoluminescence properties. However, the large-scale fabrication of homogeneous BNQDs still remains challenging. In this article, the properties and common fabrication methods of BNQDs are summarized based on the recent research progress. Then, the corresponding yields, morphologies, and fabrication mechanisms of these as-obtained BNQDs are discussed in detail. Moreover, the applications of these as-obtained BNQDs in different fields are also discussed. This article is expected to inspire new methods and improvements to achieve large-scale fabrication of homogeneous BNQDs, which will enable their practical applications in future. 相似文献
59.
Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors 下载免费PDF全文
Gao‐Feng Chen Yu‐Zhi Su Pan‐Yong Kuang Zhao‐Qing Liu Dao‐Yi Chen Xu Wu Nan Li Prof. Shi‐Zhang Qiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4614-4621
Three‐dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high‐performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D‐Ni‐core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as‐prepared material exhibits a high specific capacitance (726 F g?1 at a charge/discharge rate of 1 A g?1), good rate capability (a decay of 33 % in Csp with charge/discharge rates increasing from 1 to 20 A g?1), and high cycle stability (only a small decrease of 4.2 % in Csp after 1000 cycles at a scan rate of 100 mV s?1). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as‐prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg?1) and superior long‐term cycle ability (only 4.4 % and 18.6 % loss in Csp after 2000 and 5000 cycles, respectively). 相似文献
60.