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71.
72.
Kaushik Ghosh Pramod KumarNidhi Tyagi Udai P. SinghNidhi Goel Ajanta ChakrabortyPartha Roy Maria Camilla Baratto 《Polyhedron》2011,30(16):2667-2677
The copper complexes [Cu(Pyimpy)(H2O)](ClO4)2 (1), [Cu(Pyimpy)2](ClO4)2 (2), [Cu(Pyimpy)(Cl)2]·2H2O (3·2H2O), [Cu(Pyimpy)(N3)(ClO4)]2 (4) and [Cu(Pyimpy)(SCN)(ClO4)]2 (5) were synthesized and characterized by spectroscopic techniques, crystal structures and electrochemical studies (Pyimpy: (2-((2-phenyl-2-(pyridin-2-l)hydrazono)methyl)pyridine)). The superoxide scavenging activity of the two water soluble complexes 1 and 3 was examined. DNA interaction studies by UV-Vis absorption spectral changes during a titration experiment indicated the generation of new species. These small molecule SOD mimics exhibited excellent DNA cleavage activity in the presence of H2O2 as well as 2-mercaptoethanol. Complexes 1-5 exhibited better cytotoxicity compared to CuCl2·2H2O and the ligand Pyimpy, and showed more potency than cisplatin for MCF-7, PC-3 and HEK-293 cells. Complex 3 exhibited the highest potency for MCF-7, PC-3 and HEK-293 cells compared to the other complexes. 相似文献
73.
《Journal of Coordination Chemistry》2012,65(4):586-599
Three new copper(II) complexes [Cu(PSBP)2](NO3)(BF4) (1), [Cu(DAPBMA)2](BF4)2 (2), and [Cu(ImH)4(NO3)2] (3), where PSBP = 4-phenylsemicarbazide-2-benzoylpyridine, DAPBMA = 2,6-diacetylpyridine-bis-4-methoxyaniline, and ImH = Imidazole, have been synthesized and characterized by elemental analysis, FAB mass spectrometry, magnetic susceptibility, X-band electron paramagnetic resonance (EPR), electronic spectroscopy, and cyclic voltammetry. Frozen solution EPR spectra of the complexes have axial features with g ∥ > g ⊥ > 2.003 suggesting the presence of a d x 2? y 2 ground state. Single crystal X-ray analyses of 1–3 reveal the presence of distorted octahedral geometry. All complexes exhibit significant superoxide dismutase activity. 相似文献
74.
《Analytical letters》2012,45(13):2424-2436
Abstract A new spectrofluorimetric method was developed for determining superoxide dismutase. The interactions between prulifloxacin (PUFX) –Tb3+ complex and superoxide dismutase had been studied by using UV-Vis absorption and fluorescence spectra. Using prulifloxacin–Tb3+ as a fluorescence probe, under optimum conditions, superoxide dismutase could remarkably enhance the fluorescence intensity of the prulifloxacin–Tb3+ complex at λ = 545 nm, and the enhanced fluorescence intensity was in proportion to the concentration of superoxide dismutase. Optimum conditions for the determination of superoxide dismutase were also investigated. The dynamic range for the determination of superoxide dismutase was 0.032 to 22.56 µg mL?1, and the detection limit (S/N = 3) was 1.5 ng 4 mL?1. This method was simple, practical, and relatively free of interference from coexisting substances and could be successfully used to determine superoxide dismutase in the plant and blood samples. The mechanism of fluorescence enhancement of prulifloxacin–Tb3+ complex by superoxide dismutase was also discussed. 相似文献
75.
Likhtenshtein GI 《Applied biochemistry and biotechnology》2009,152(1):135-155
We proposed and developed a series of fluorescent methods for analysis and investigation of biological systems with a view
of future biotechnological and biomedical applications. The methods we describe have been built upon several photochemical
and photophysical phenomena including fluorescent quenching, photochrome photoisomerization, and energy transfer. Three new
types of molecular probes have been developed and employed for such studies: (1) dual fluorophore–nitroxide compounds, (2)
fluorescence–photochrome molecules, and (3) super molecules containing both fluorescence and fluorescent quenching segments.
The fluorescent properties of the new probes were intensively exploited for several practical applications including a real-time
analysis of antioxidants, nitric oxide, superoxide, reactive radicals, trinitrotoluene, and metal ions, investigation of molecular
dynamics of biomembranes in a wide range characteristic times, detection of protein conformational transition, and characterization
of surface system. Owning high sensitivity, simplicity, and availability of fluorescent techniques, these methods can be widely
employed and are adaptable to fibrooptic sensoring. A general survey of the physical principles and application of the new
fluorescent methods has been provided. 相似文献
76.
Lata Chouhan Sushant Ghimire Vasudevanpillai Biju 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):4929-4933
Moisture‐ or oxidation‐induced degradation is a major challenge in the advancement of perovskites‐based technology. The oxidation is caused by electron transfer from a photo‐excited perovskite nanocrystal to oxygen and the formation of superoxide that disintegrates the perovskite structure. In air, the emission intensity of a methylammonium lead iodide (MAPbI3) perovskite nanocrystal continuously decreases, whereas a nanocrystal in argon or a polymer shows exceptionally stable emission intensity. Surprisingly, in air, the emission intensity of a nanocrystal with long‐lived OFF states completely recovers after the OFF state. This property, along with the rate of non‐radiative relaxation that exceeds the rate of electron transfer suggest that the perovskite nanocrystals produce and react with superoxide in the excited neutral state, but not in the ionized state. In other words, the ultrafast non‐radiative relaxation in the ionized state hinders electron transfer to oxygen and prevents oxidation of perovskites. 相似文献
77.
On account of excellent thermal physical properties, molten nitrates/nitrites salt has been widely employed in heat transfer and thermal storage industry, especially in concentrated solar power system. The thermal stability study of molten nitrate/nitrite salt is of great importance for this system, and the decomposition mechanism is the most complicated part of it. The oxide species O22- and O2- were considered as intermediates in molten KNO3-NaNO3 while hard to been detected in high temperature molten salt due to their trace concentration and low stability. In this work, the homemade in situ high temperature UVVis instrument and a commercial electron paramagnetic resonance were utilized to supply evidence for the formation of superoxide during a slow decomposition process of heat transfer salt (HTS, 53 wt% KNO3/40 wt% NaNO2/7 wt% NaNO3). It is found that the superoxide is more easily generated from molten NaNO2 compared to NaNO3, and it has an absorption band at 420-440 nm in HTS which red shifts as temperature increases. The band is assigned to charge-transfer transition in NaO2 or KO2, responsible for the yellow color of the molten nitrate/nitrite salt. Furthermore, the UV absorption bands of molten NaNO2 and NaNO3 are also obtained and compared with that of HTS. 相似文献
78.
用清除超氧阴离子自由基法评价竹叶提取物抗氧化能力 总被引:28,自引:1,他引:27
通过对邻苯三酚反应体系的吸收光谱,对自氧化速率及邻苯三酚浓度和缓冲液pH值对反应体系产生的超氧阴离子自由基清除率的影响进行了研究.分光光度法测定邻苯三酚反应体系的检测波长为319.5眦,反应体系体积10 mL,反应时间为9 min,3 mmol·L-1邻苯三酚加入量为0.3 mL,Tris-HCl缓冲液pH值为8.2,自氧化速率为0.035;用上述方法研究合成抗氧化剂叔丁基对苯二酚(TBHQ)和竹叶提取物样品浓度和清除率的关系,以IC50值(清除率为50%时的浓度值)作为评价指标,测得TBHQ和效果最好样品的IC50值分别为TBHQ(95.01 mg·L-1)和M40(298.69 mg·L-1),M40等竹叶提取物可以作为天然抗氧化剂进行开发. 相似文献
79.
新型兼具GPX,SOD, CAT活性的水杨醛Schiff碱衍生物的合成 总被引:1,自引:0,他引:1
以5-磺基水杨醛为母体, 经氯甲基化和硒化反应引入催化基团-SeH, 此化合物经空气氧化、Schiff碱反应以及锰螯合反应, 最终得到一种新型的水杨醛Schiff碱类谷胱甘肽过氧化物酶(GPX)模拟物. 测定了该模拟物的红外光谱、核磁共振谱、质谱和抗氧化能力. 此模拟物同时兼具超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性, 水溶性好, 保护线粒体免遭氧化损伤能力强, 具有作为药物前体的潜力. 相似文献
80.
采样极谱法测定SOD模型化合物催化超氧离子歧化反应速率常数 总被引:3,自引:0,他引:3
用采样极谱法研究了非质子溶剂中SOD模型化合物催化O2-的歧化反应,用简化的函数关系代替动力学微分方程的准确解.通过测定极限催化电流与极限扩散电流比随SOD模型化学物浓度及滴汞电极滴下时间的变化,确定催化O2-歧化反应速率常数K1. 相似文献