全文获取类型
收费全文 | 2843篇 |
免费 | 510篇 |
国内免费 | 575篇 |
专业分类
化学 | 3462篇 |
晶体学 | 19篇 |
力学 | 32篇 |
综合类 | 11篇 |
数学 | 4篇 |
物理学 | 400篇 |
出版年
2024年 | 33篇 |
2023年 | 53篇 |
2022年 | 141篇 |
2021年 | 211篇 |
2020年 | 380篇 |
2019年 | 178篇 |
2018年 | 149篇 |
2017年 | 103篇 |
2016年 | 215篇 |
2015年 | 175篇 |
2014年 | 175篇 |
2013年 | 262篇 |
2012年 | 133篇 |
2011年 | 114篇 |
2010年 | 84篇 |
2009年 | 109篇 |
2008年 | 131篇 |
2007年 | 123篇 |
2006年 | 137篇 |
2005年 | 117篇 |
2004年 | 97篇 |
2003年 | 99篇 |
2002年 | 76篇 |
2001年 | 51篇 |
2000年 | 49篇 |
1999年 | 38篇 |
1998年 | 48篇 |
1997年 | 37篇 |
1996年 | 39篇 |
1995年 | 20篇 |
1994年 | 23篇 |
1993年 | 25篇 |
1992年 | 26篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 22篇 |
1988年 | 22篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 9篇 |
1982年 | 20篇 |
1981年 | 20篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1973年 | 8篇 |
排序方式: 共有3928条查询结果,搜索用时 15 毫秒
931.
Gel polymer composites electrolytes containing nano LiAlO2 as filler were prepared using a solution cast technique and characterized using different techniques such as X-ray diffraction (XRD), thermal analysis (TG, DSC), Fourier transform infra – red spectroscopy (FT-IR) and scanning electron microscope (SEM). X-ray diffraction analysis showed the effect of lithium tri fluoro methane sulphonate (LiCF3SO3), poly vinyl acetate (PVAc) and nano lithium aluminate (LiAlO2) on the crystalline structure of the poly vinylidene fluoride –co– hexa fluoro propylene (PVDF-co-HFP) matrix containing ethylene carbonate (EC) and diethyl carbonate (DEC) as plasticizers. FT-IR analysis confirmed both the good dissolution of the LiCF3SO3 salt and the good interaction of the nano LiAlO2 filler with the polymer matrix. TG analysis showed the good thermal stability of the LiAlO2 samples compared to the free one. Also, addition of nano LiAlO2 filler enhanced the conductivity value of the polymer composites electrolytes. The sample containing 2 wt% of LiAlO2 showed the highest conductivity value, 4.98 × 10−3 Ω −1 cm−1 at room temperature, with good thermal stability behavior (Td = 362 °C). This good conductive and thermally stable polymer nano composite electrolyte was evaluated as a promising membrane for lithium ion batteries application. 相似文献
932.
《Green Chemistry Letters and Reviews》2013,6(3-4):13-16
ABSTRACTA small amount of ferric hydroxide was found to catalyze KI-activated coupling of aromatic aldehydes and acetophenone to give the corresponding pinacols in high yields. The ratio of meso to dl isomer was approximately 1:1. Most aliphatic aldehydes and ketones were unreactive under the same conditions. 相似文献
933.
Qi Pan Hui Chen Zhenguo Wu Yuan Wang Benhe Zhong Li Xia Prof. Hai-Ying Wang Prof. Guanwei Cui Prof. Xiaodong Guo Prof. Xuping Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(4):971-975
The design and development of electrode materials with high specific capacity and long cycling life for sodium-ion batteries (SIBs) is still a critical challenge. In this communication, we report the development of tungsten phosphide (WP) nanowire on carbon cloth (WP/CC) as an anode for SIBs. The WP/CC exhibits superior sodium storage capability with 502 mA h g−1 at 0.1 A g−1. Moreover, this anode is capable of delivering a long lifespan at 2 A g−1 with an excellent capacity retention of 99 % after 1000 cycles. 相似文献
934.
《中国化学会会志》2017,64(5):539-546
Porous Co3O4 nanosheets were designed and fabricated from common Co(NO3 )2 solution without any surfactants or templates under microwave radiation conditions. After the microstructures and morphologies were characterized by scanning electron microscope (SEM ), X‐ray powder diffraction (XRD ), transmission electron microscopy (TEM ), and N2 absorption/desorption isotherms techniques, the obtained Co3O4 nanosheets were applied for reversible Li‐storage, displaying larger capacity, better cycling performance and rate capability, i.e., a reversible specific capacity of ca. 800 mAh /g during initial 30 cycles and a reversible capacity of 450 mAh /g at 2C for Co3O4 nanosheets, which were almost twice higher than those for Co3O4 nanoparticles. The improved cycling stability could be attributed to the remarkable synergistic effects between porous structures and nanosheet‐like morphologies. 相似文献
935.
AbstractThe aim of the study was to evaluate the effect of leaf extracts of four plants against some isolated fungal species from deteriorated books. Aqueous, methanol and chloroform extracts of selected plant species were screened in vitro for their antifungal activity against some book deteriorating fungal species. Fifteen species belonging to 09 genera were isolated and identified from infested books in library. Aqueous and solvent extracts of leaves of Azadiracta indica, Callistemon citrinus, Eucalyptus lanceolatus and Pongamia pinnata were tested against some dominant fungal species viz. Chaetomium spiralis, Alternaria alternata, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus and Rhizopus stolonifer. Solvent extracts exhibited potent inhibitory activity than aqueous extracts. However, these plant extracts exhibited moderate activity against A. flavus, C. spiralis, R. stolonifer and A. alternata. 相似文献
936.
Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) test, smoke toxicity analysis and mouse biological toxicity test were carried out on the second use lithium-ion battery separator and electrolyte. It was found that the types of cracked products of separator and electrolyte under different state of health (SOH) were basically the same, mainly phosphoryl fluoride (POF3) and long-chain F-containing alkanes, alcohols and esters. The content of POF3 in the cracked product increases as the SOH increases. The toxic gas components released after the separator and the electrolyte are completely burned mainly include CO, CO2, and HF. The HF content decreased as the battery SOH decreased, from 101.6 mg/g of the 100% SOH battery to 44.1 mg/g of the 65% SOH battery. In the biological toxicity test, all the mice were found to stop running, close eyes, shed tears, and have shortness of breath. After the test, only 65% SOH and 100% SOH mice recovered their body weight to the pre-experimental average state and gained weight. 相似文献
937.
938.
Xingyu Yu Guoping Liu Assoc. Prof. Tao Wang Assoc. Prof. Hao Gong Hongjiao Qu Prof. Xianguang Meng Prof. Jianping He Prof. Jinhua Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(66):e202202104
The application of solar energy is crucial for alleviating the energy crisis and achieving sustainable development. In recent years, photo-assisted rechargeable batteries have attracted researchers because they can directly convert and store solar energy in the batteries. And it also can be used like a normal battery without light illumination. Photo-assisted lithium-based batteries have received more attention than other energy storage systems due to their higher energy density and relatively mature development. This Review focuses on the design of various photo-assisted lithium-based batteries including Li-ion, Li-S, Li-O2, Li-CO2 and Li-I batteries, as well as the working mechanism of photoelectrodes in these battery systems. The basic understanding and challenge of photo-assisted lithium-based batteries are also discussed. At last, perspectives for the photoelectrode development are provided in the summary to advance photo-assisted energy storage systems. 相似文献
939.
940.