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271.
Synthesis of [n]Cyclo‐5,15‐porphyrinylene‐4,4′‐biphenylenes Displaying Size‐Dependent Excitation‐Energy Hopping 下载免费PDF全文
Dr. Hua‐Wei Jiang Dr. Takayuki Tanaka Taeyeon Kim Young Mo Sung Hirotaka Mori Prof. Dr. Dongho Kim Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(50):15197-15201
A set of 5,15‐biphenylene‐bridged porphyrin wheels, namely, [n]cyclo‐5,15‐porphyrinylene‐4,4′‐biphenylenes [n]CPB , have been synthesized through the platination of 5,15‐bis(4‐(pinacolboranyl)phenyl) nickel(II) porphyrin and subsequent reductive elimination of PtII(cod)‐bridged cyclic porphyrin intermediates. The calculated strain energies for [3]CPB , [4]CPB , [5]CPB , and [6]CPB are 49.3, 32.9, 23.5, and 16.0 kcal mol?1, respectively. UV/Vis absorption spectra and cyclic voltammetry indicated characteristic ring‐size‐dependent absorption‐peak shifts and redox‐potential shifts, which presumably reflect the degree of strain in the π‐systems. Excitation‐energy hopping (EEH) times were determined to be 5.1, 8.0, 8.0, and 9.6 ps for [3]CPB , [4]CPB , [5]CPB , and [6]CPB , respectively, in a pump‐power‐dependent TA experiment. 相似文献
272.
邻菲哕啉光度法常用于Fe(Ⅱ)测定,但受到试样中Fe(Ⅲ)对测定的影响,因此不能直接用于生物浸出样品中Fe(Ⅱ)和Fe(Ⅲ)的同时测定.为此,基于Fe(Ⅱ)邻菲哕啉特征吸收曲线以及混合铁中Fe(Ⅲ)对Fe(Ⅱ)测定的线性影响关系,建立了基于Fe(Ⅱ)和全铁同时测定Fe(Ⅱ)和Fe(Ⅲ)的计算光度法,并研究了生物浸出样品中典型金属离子(Cu^2+、Ni^2+、Cd^2+、Co^2+)以及试样溶解与储放对测定的影响.方法可准确地测定含铁次生矿物和生物浸出液中铁价态组成,应用于生物浸出矿渣、细胞表面中常量或微量的Fe(Ⅱ)和Fe(Ⅲ)组成分析,具有简便快速的特点. 相似文献
273.
向Fe(Ⅲ)—柠檬酸水溶液体系中加入无水乙醇,并经放置处理等,体系中(?)_(Fe)Ⅲ(Fe(Ⅲ)各种形式平均克磁化率)比水体系及未经放置的加醇体系有所增加,pH滴定曲线终点前移,紫外、可见光度揭示有新物种生成,我们认为体系中可能生成了含醇的多元配合物,机理有待进一步探讨。 相似文献
274.
275.
胜利褐煤燃烧中未反应残留物结构特性及铁的添加效应 《燃料化学学报》2016,44(12):1447-1456
利用TGA确定胜利褐煤盐酸脱灰煤和添加铁组分脱灰煤的着火温度,在着火温度进行燃烧反应,收集燃烧反应一定时间后的未反应残留物,利用FT-IR、XPS、XRD和Raman等对其进行表征,研究了胜利褐煤燃烧过程中铁的影响规律。结果表明,铁的加入降低脱灰胜利褐煤的着火温度,当添加量为3.50%时,着火温度降低的幅度最大。在着火温度燃烧反应一定时间后未反应残留物的FT-IR表明,其有机官能团结构无显著变化,说明铁的添加并不影响其有机官能团结构特性,有机官能团不会对燃烧性能产生太大的影响。添加铁使SL+在燃烧过程中未反应残留物结构芳香度下降,晶面间距增大,晶体结构中缺陷位相对增加,石墨化程度降低,烷基侧链增多,碳氧结构迅速减少,说明铁组分的加入改变了其燃烧过程中碳氧结构转化特性,抑制了石墨化转化速率与程度,即在燃烧反应过程中改变了其未反应残留物的微结构,从而改变了其反应历程,加速燃烧反应速率。 相似文献
276.
277.
A graph G is called T-unique if any other graph having the same Tutte polynomial as G is isomorphic to G. Recently, there has been much interest in determining T-unique graphs and matroids. For example, de Mier and Noy [A. de Mier, M. Noy, On graphs determined by their Tutte polynomials, Graphs Combin. 20 (2004) 105-119; A. de Mier, M. Noy, Tutte uniqueness of line graphs, Discrete Math. 301 (2005) 57-65] showed that wheels, ladders, Möbius ladders, square of cycles, hypercubes, and certain class of line graphs are all T-unique. In this paper, we prove that the twisted wheels are also T-unique. 相似文献
278.
Transition-metal-salt-mediated radical reactions of fullerenes have attracted extensive attention as a new and important method for fullerene functionalization. The application of relatively cheap and easily available ferric perchlorate (Fe(ClO 4 ) 3 ) to the synthesis of [60]fullerene (C 60 ) has demonstrated remarkable advantages and afforded a series of novel fullerene derivatives. In this review we present our recent progress in this area and summarize the reactions of C 60 with malonate esters, β-keto esters, nitriles, aldehydes/ketones, and arylboronic acids in the presence of Fe(ClO 4 ) 3 to afford the C 60-fused disubstituted lactones, C 60-fused hemiketal, C 60-fused dihydrofuran, C 60-fused oxazoles, C 60-fused 1,3-dioxolanes, and fullerenyl boronic esters. The possible reaction mechanisms for the above-mentioned reactions are also described in detail. 相似文献
279.
Formation of free radical intermediates in a NaOH/H(2)O(2)/Fe(III) system has been studied by ESR spectroscopy in the presence of the spin trap 5,5-dimethy-1-pyrroline N-oxide (DMPO). DMPO/O(2(*) ) (-) and DMPO/(*)OH signals were simultaneously detected in this system, but only the DMPO/(*)OH signal could be observed in the absence of Fe(III). Effects of pH values and Fe(III) concentrations on the ESR signal intensities were investigated in detail. Formation of DMPO/O(2(*) ) (-) adduct was inhibited by the addition of superoxide dismutase (SOD), catalase or nitro blue tetrazolium (NBT), and by chelating the Fe(III) with some chelators, including ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and desferrioxamine (DFO). Deoxygenation from the NaOH/H(2)O(2)/Fe(III) mixture had a slight effect on the formation of DMPO/O(2(*) ) (-). DMPO/O(2(*) ) (-) signal was also detected from the NaOH/H(2)O(2)/Fe(II) mixture, but it can be totally suppressed under anaerobic conditions. Considering the hydrolysis of Fe(III) into polymerization iron species with oxide phases in the alkaline medium, Fe(2)O(3) was directly suspended into a mixture of NaOH/H(2)O(2) for comparison. Fortunately, the presence of Fe(2)O(3) suspension was found to be of benefit to the production of DMPO/O(2(*) ) (-). Influence of aging time of hydrolytic iron species on the superoxide anion radical generation was also studied. These results suggest that the generation of O(2(*) ) (-) from the NaOH/H(2)O(2)/Fe(III) system was probably caused by the heterogeneous surface catalysis initiated by hydrolytic iron species. 相似文献
280.
Chen Ling Yixuan Zhao Zixi Ren Jiangang Han Changqing Zhu Fu-Qiang Liu 《中国化学快报》1990,30(12):2196-2200
A novel Fe/amine modified chitosan composite (Fe/N-CS) was facilely synthesized and showed great potential in the efficient co-removal of heavy metal ions and antibiotics from wastewater. 相似文献