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排序方式: 共有1102条查询结果,搜索用时 468 毫秒
1.
Donglei Wei Huili Li Chuanqing Yang Jianmin Fu Hou Chen Liangjiu Bai Wenxiang Wang Huawei Yang Lixia Yang Ying Liang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1588-1594
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst. 相似文献
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3.
傅里叶变换技术在紫外可见光谱区的应用 总被引:13,自引:3,他引:13
本文评述了傅里叶变换在紫外可见光谱区的应用,探讨了傅里叶变换在紫外可见光谱学以及信号处理两方面的内容。详细介绍了傅里叶变换在紫外可见区遇到的问题、主要优点和发展前景。 相似文献
4.
前言卟啉在生物化学、分析化学、药物化学等领域有着广泛研究和重要应用[1~3]。近年来虽然对卟啉类化合物的研究报道很多[4~6],但对卟啉在酸性介质中的研究很少。较早期的研究工作认为卟啉类化合物在酸性介质中仅以其二酸形式存在[7]。本文实验结果显示me... 相似文献
5.
Preparation and characterization of nitrogen-doped TiO2 photocatalyst in different acid environments
Ye Cong Ling Xiao Jinlong Zhang Feng Chen Masakazu Anpo 《Research on Chemical Intermediates》2006,32(8):717-724
Nitrogen-doped TiO2 powders were successfully prepared by a wet method, i.e., a micro-emulsion-hydrothermal method, in different acid environments.
Several characterization techniques, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse
reflectance spectra, were combined to determine the crystal phase, concentration and chemical states of the nitrogen doped
in TiO2. The high photocatalytic activity of the nitrogen-doped TiO2 was evaluated through the decomposition of rhodanmine B under visible light irradiation. It was suggested that the doped
nitrogen formed oxynitride (NO) and produced impurity states at higher above the valence band of TiO2. Therefore, the nitrogen doping could enhance the response of photocatalyst to the visible light and improve the photocatalytic
activity because of the narrowing of band gap of TiO2. 相似文献
6.
Norman S. Allen 《Journal of photochemistry and photobiology. A, Chemistry》1996,100(1-3):101-107
The radiation curing industry is one of the most rapidly developing fields in the entire coatings industry. The low toxicity, cheapness, speed, control and ease of formulation and operation are some of the main advantages of this growing technology. UV and/or visible light radiation is used to induce photochemical polymerization or crosslinking of a monomer, oligomer or prepolymer formulation containing a certain type of unsaturation, such as an acrylic group, and an appropriate initiator. The latter is used to absorb the light energy and transform it into active species, such as radicals or ions, capable of inducing such reactions. Applications extend to general coatings for paper, board, wood, tapes, compact discs and holograms, inks, photoresists for imaging processes and adhesives for welding and sealing in electronic circuit boards. The photoinitiator is the key to the control of these processes and, in recent years, has seen many new developments. These include the need for water-soluble, co-reactive and polymeric structures with low migration rates, as well as cheaper UV/ visible sensitizers with enhanced speed. New and effective cationic systems are also on the scene and, although expensive, are attracting significant academic and commercial interest. 相似文献
7.
Several new methyl-substituted indenyl ferrocenes were prepared by metathesis reactions of the indenide (generated from the appropriate indene with BuLi) with ferrous chloride. The indenides used to prepare new ferrocenes were: 2-methyl-, 1,2-dimethyl-, 4,7-dimethyl-, 1,4,7-trimethyl-, and 1,3,4,7-tetramethyl-indenide. These indenyl ferrocenes, along with those prepared from indenide, 1-methylindenide, and 1,3-dimethylindenide, were then characterized by 1H and 13C NMR, UV/visible spectroscopy, cyclic voltammetry and mass spectrometry. The cyclic voltammetry showed an additive relationship between oxidation potential and the number of methyl groups which is also position-dependent, whereas the UV/visible spectra showed two absorptions essentially unaffected by methyl substitution. Additionally, bis(2-methylindenyl)iron(II) and bis(4,7-dimethylindenyl)iron(II) were characterized by X-ray crystallography. 相似文献
8.
9.
Liliana N. Trevani Jenene C. Roberts Peter R. Tremaine 《Journal of solution chemistry》2001,30(7):585-622
The spectra of copper(II)–ammonia solutions in 2 mol-kg–1 NH4NO3(aq) were recorded as a function of pH with a new UV–visible flow cell, capable of operating at conditions up to 325°C and 300 bars. Equilibrium constants for the formation of copper(II)–ammonia complexes Cu(NH3)n
2+, 1 n 4, from 30 to 150°C were determined by evolving factor analysis and nonlinear least-squares regression. Measurements at higher temperatures were limited by thermal decomposition of NH4NO3(aq). The formation constants of Cu(NH3)n
2+ decrease with temperature, consistent with extrapolations of literature data from measurements below 100°C. Measurements above 150°C were carried out in 0.5 mol-kg–1 CF3SO3H (aq), at the very high ammonia concentrations required to avoid the precipitation of CuO(s). The spectra are consistent with Cu(NH3)4
2+ as the predominant species, based on extrapolations of peak maxima and molar absorptivities from lower temperatures. Shifts in the spectra of Cu2+ and the Cu(NH3)n
2+ species to higher wavelength and increases in molar absorbance with increasing temperature are discussed in terms of the structure of the complexes. 相似文献
10.
N掺杂可见光化催化剂的研究 总被引:1,自引:0,他引:1
The N-doped, yellow colored titanium oxide photocatalysts were prepared with Ti(SO4)2 and NH4HCO3 as precursors by precipitation method. The photocatalytic ability under the irradiation of UV or visible light for the catalysts prepared was studied by degradation of styphnic acid. The materials were characterized by EDS, XRD, FTIR, UV-Vis DRS, and XPS. The results indicate that the photocatalytic ability of catalysts is improved, especially the ability of visible light response. The results of UV-Vis DRS show that the response wavelength range of N-dopped nitrogen is red shifted, the absorption region is expanded to 476 nm. 相似文献