全文获取类型
收费全文 | 1068篇 |
免费 | 151篇 |
国内免费 | 165篇 |
专业分类
化学 | 950篇 |
晶体学 | 21篇 |
力学 | 22篇 |
综合类 | 38篇 |
数学 | 23篇 |
物理学 | 330篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 57篇 |
2021年 | 51篇 |
2020年 | 51篇 |
2019年 | 30篇 |
2018年 | 39篇 |
2017年 | 45篇 |
2016年 | 52篇 |
2015年 | 43篇 |
2014年 | 64篇 |
2013年 | 68篇 |
2012年 | 79篇 |
2011年 | 59篇 |
2010年 | 58篇 |
2009年 | 59篇 |
2008年 | 62篇 |
2007年 | 77篇 |
2006年 | 63篇 |
2005年 | 67篇 |
2004年 | 49篇 |
2003年 | 49篇 |
2002年 | 38篇 |
2001年 | 40篇 |
2000年 | 33篇 |
1999年 | 19篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有1384条查询结果,搜索用时 15 毫秒
211.
XIAO Yi CHEN Fang ZHU Xixi QIN Hongling HUANG Hongmei ZHANG Youyu YIN Dulin HE Xiaoxiao WANG Kemin 《高等学校化学研究》2015,31(6):899-903
New lanthanide metal-organic framework(MOF) nano/microrods, [C4mim]Cl-Eu-MOF, [C8mim]Cl-Eu- MOF and [C12mim]Cl-Eu-MOF, were conveniently synthesized via an ionic liquid-assisted hydrothermal method and characterized by means of powder X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), thermogravimetric analysis(TG) and transmission electron microscopy(TEM). The obtained nano/microrods with low surface areas were efficient for the removal of Congo red(CR) from aqueous solutions. Under the optimum conditions, [C4mim]Cl-Eu-MOF with a specific surface area of 5.1 m2/g exhibited an ultrahigh adsorption capacity of 2606 mg/g toward CR. Notably, the adsorption efficiency of [C4mim]Cl-Eu-MOF for CR via nano/microscale stacking can be directly demonstrated by TEM. In-depth understanding of CR removal by [C4mim]Cl-Eu-MOF nano/microrods was also supported by FTIR, Raman spectroscopy and zeta potential analyses. 相似文献
212.
Diketopyrrolo[3,4-c]pyrroles (DPP) are high-performance organic optoelectronic materials. They have applications in solar cells, fluorescent probes, bioimaging, photodynamic/photothermal therapy, and in many other areas. This article reports a convenient two-step synthesis of various DPP dyes from Pigment Red 254, an inexpensive commercial pigment. The synthesis includes a Suzuki–Miyaura cross-coupling reaction of a bis(4-chlorophenyl)DPP derivative with aryl and hetaryl boronic acids under mild reaction conditions. The new dyes show large Stokes shifts and high fluorescence quantum yields, important features for their potential use in technical and biological applications. 相似文献
213.
基于红色荧光染料3-(dicyanomethylene)-5, 5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene的高性能白色有机电致发光器件 下载免费PDF全文
研究了基于红色荧光染料3-(dicyanomethylene)-5, 5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene(DCDDC)的白色有机电致发光器件的性能,分别制备了基于DCDDC超薄层和DCDDC掺杂主体材料的两种器件结构: 1)indium-tin oxide(ITO)/N, N′-diphenyl-N, N′-bis(1-naphthyl-pheny1)-1, 1′-biphenyl-4,
关键词:
有机电致发光器件
白色发光
红色荧光染料
掺杂 相似文献
214.
吖啶红-SLS体系共振瑞利散射法测定蛋白质 总被引:7,自引:0,他引:7
研究了吖啶红染料与蛋白质的结合反应。在十二烷基磺酸钠存在下及pH2.90的柠檬酸NaOH介质中,蛋白质与吖啶红形成复合物,使最大波长392nm的共振光散射光谱得到加强,根据其共振光散射的增强程度,可用于蛋白质的定量测定。十二烷基磺酸钠的加入,使灵敏度提高11倍,牛血清白蛋白、γ球蛋白的线性范围分别为0.03~0.7mg/L、0.05~1.3mg/L,检出限分别为6.4μg/L、10.8μg/L。用于人血清、牛奶、豆浆、尿液中总蛋白质的测定,结果与经典的考马斯亮蓝G 250法一致。 相似文献
215.
216.
溶剂对光致变色材料-乙基红的光学特性影响 总被引:2,自引:0,他引:2
研究了溶剂性质对光致变色材料乙基红光学性质的影响.用吸收谱测定了乙基红染料在不同溶剂中的溶剂化位移.对相同浓度多种乙基红溶液进行了Z-scan测量,测量了不同乙基红溶液的光限幅效应,并讨论了其与溶剂之间的关系.随极性增加,吸收谱蓝移,可以通过选择不同溶剂,改变非线性材料的应用窗口.实验结果表明,在连续光照射下,乙基红溶液的非线性折射主要由热效应引起,非线性折射系数n2受溶剂的热学性质影响较大.此外,Z-scan结果中的非线性吸收为饱和吸收.至于光限幅效应,主要受热效应影响,但亦可由吸收谱预测出在某波长处的动态范围.得出的结论有助于偶氮染料作为非线性材料的应用. 相似文献
217.
218.
219.
R. Maeikien K. Balskus O. Eicher-Lorka G. Niaura R. Mekys A. Malinauskas 《Vibrational Spectroscopy》2009,51(2):238-247
The redox dye Neutral red (NR), adsorbed and electropolymerized at a roughened gold electrode, has been studied by Raman spectroscopy at λex of 676.4 nm in an electrochemical cell. Spectral bands have been assigned based on density functional theory (DFT) calculations. The number and position of the bands, as well as their intensity depend on electrode potential, allowing one to discern different redox forms of NR or its polymer. The observed changes in band positions and intensities have been analyzed. Electrooxidation of hydroquinone and ascorbic acid at a gold electrode modified with adsorbed or electropolymerized layer of NR has been studied with in situ Raman spectroelectrochemical technique. During electrooxidation of solution species, NR layer contains both oxidized and reduced forms of this modifier. It has been shown that the relative content of a reduced form of NR at electrode surface increases with increasing concentration of any of oxidizable species used. It has been concluded that anodic oxidation of ascorbic acid or hydroquinone at NR or polyNR modified electrode proceeds within the modifier layer rather than at a modifier/electrolyte interface. In this respect, electrooxidation follows a redox mechanism. 相似文献
220.
The organo-attapulgite was prepared using hexadecyltrimethylammonium bromide (HTMAB) with equation equivalent ratio of HTMAB
to CEC of attapulgite added and then used as adsorbent for the removal of Congo red (CR) anionic dye from aqueous solution.
Adsorbent characterizations were investigated using infrared spectroscopy and X-ray diffraction. The effects of contact time,
temperature, pH and initial dye concentration on organo-attapulgite adsorption for CR were investigated. The results show
that the amount adsorbed of CR on the organo-attapulgite increase with increasing dye concentration, temperature, and by decreasing
pH. The adsorption kinetics was studied with the pseudo-first-order, pseudo-second-order and intraparticle diffusion models,
and the rate constants were evaluated. It was found that the adsorption mechanisms in the dye/organo-attapulgite system follow
pseudo-second-order kinetics with a significant contribution of film diffusion. Equilibrium data fitted perfectly with Langmuir
isotherm model compared to Freundlich isotherm model, and the maximum adsorption capacity was 189.39 mg g−1 for the adsorbent. Kinetic and desorption studies both suggest that chemisorption should be the major mode of CR removal
by the organo-attapulgite. The results indicate that HTMAB-modified attapulgite could be employed as low-cost material for
the removal of Congo red anionic dye from wastewater. 相似文献