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81.
Emregül E 《Analytical and bioanalytical chemistry》2005,383(6):947-954
A superoxide dismutase (SOD) biosensor for determination of superoxide radicals has been developed by immobilization of superoxide
dismutase within gelatin (G) on a Pt electrode surface. The properties of the biosensor have been investigated and optimum
conditions–enzyme concentration, glutaraldehyde concentration, and pH–were determined. The response of the G-SOD biosensor
was proportional to concentration and the detection limit was 0.01 mmol L−1 at a signal-to-noise ratio of 3. The biosensor retained 89% and 60% of its sensitivity after use for three and four weeks,
respectively. Immobilization of SOD on gelatin provides a biocompatible microenvironment around the enzyme and stabilizes
the activity of the enzyme very efficiently. The superoxide dismutase biosensor was used to determine the antioxidant properties
of acetylsalicylic acid-based drugs and the anti-radical activity of healthy and cancerous human brain tissues. 相似文献
82.
含铜(Ⅱ)、铁(Ⅲ)、锰(Ⅱ)双核模型化合物的超氧化物歧化酶活性 总被引:3,自引:0,他引:3
用邻苯三酚自氧化法测定自合成的N,N,N,N’,N’-四(2’-苯并咪唑甲基)-1,4-二乙氨基乙二醚(EGTB)的双核铜(Ⅱ)、铁(Ⅲ)、锰(Ⅱ)配合物的超氧化物歧化酶活性,它们均在10~(-6)~10~(-7)mol/L的浓度范围内具有50%以上的抑制率。 相似文献
83.
本文以大肠杆菌内毒素攻击介导的感染性多系统脏器功能衰竭家兔为模型,探讨了血清的特异荧光。应用发光理论讨论了模型血清的分子光谱,以及感染性多脏衰竭进程与特异荧光的关系。同时,还制定了血液、心、肝、肺、肾各组织器官中脂过氧化物代谢产物丙二醛和超氧化物歧化酶变化情况,结果具有明显的相关性和一致性。荧光法可作为感染性多脏器衰竭的早期诊断预示的一种方法。 相似文献
84.
85.
《Analytical letters》2012,45(4):601-611
Abstract Metallothionein-II (MT-II) and Cu, Zn-superoxide dismutase (Cu, Zn-SOD) interacted with mercury were detected by a new method utilizing isoelectric focusing-agarose or -polyacrylamide gel electrophoresis (IEF-AGE or IEF-PAGE) and nondestructive one-dimensional synchrotron radiation X-ray fluorescence (SR-XRF) analysis. When MT-II reacted with mercuric chloride, an obvious change of isoelectric point (pI = 3.7 - 4.7) for the intact form to alkaline pI (9.4) was observed. This marked migration of MT-II by the metal was blocked by addition of glutathione, suggesting that sulfhydryl functions participate in the pI variation. In contrast, interaction of Cu, Zn-SOD with mercury did not cause any changes of its pI although the metal bound tightly to Cu, Zn-SOD after electrophoresis; however, the enzyme activity was drastically suppressed. These observations indicate that combination of electrophoresis with SR-XRF analysis is an useful technique for detecting structural or functional alteration of protein attributable to the binding of the mercury. 相似文献
86.
Catalysis of the electrochemical oxygen reduction reaction (ORR) on a pyrolytic graphite electrode (PGE) by iron-containing
superoxide dismutase (Fe-SOD) is investigated for the first time using cyclic voltammetry and electrochemical impedance spectroscopy.
The study is carried out in three room-temperature ionic liquids (RTILs), namely, 1-ethyl-3-methylimidazolium tetrafluoroborate
(EMIBF4), 1-propyl-3-methylimidazolium tetrafluoroborate (PMIBF4), and 1-butyl-3-methylimidazolium tetrafluoroborate (EMIBF4). The results demonstrate that in EMIBF4, Fe-SOD exhibits the most satisfactory catalysis for ORR, with the standard rate constant of ORR on bare PGE, k
s, increasing from 3.9 to 5.1 times 10−3 cm s−1, while in PMIBF4 and BMIBF4 containing Fe-SOD k
s increases from 2.6 to 3.6 and from 1.4 to 2.2 times 10−3 cm s−1, respectively. In addition to the increased k
s, adding Fe-SOD renders the formal potential of ORR more positive. To accelerate the electron transfer, multi-walled carbon
nanotubes (MWCNTs) are employed to modify PGE, consequently, yielding the dramatically increased peak current and k
s. For MWCNTs-modified PGE in EMIBF4 free of Fe-SOD, k
s increases from 3.9 to ∼7.1 times 10−3 cm s−1. The ORR catalysis by Fe-SOD in the presence of Fe-SOD is also evidenced by the formal-potential shift in the positive direction.
With MWCNTs accounting for the larger k
s and Fe-SOD being responsible for the formal-potential shift, the catalysis of ORR is satisfactory. Chronocoulmetry experiments
proved that some Fe-SOD could be adsorbed on PGE. After analyzing the results, dismutation of superoxide anion O
2
−
by Fe-SOD is thought to be the main reason for the formal-potential shift. The different polarity of RTILs is probably partly
responsible for different k
s obtained in different RTILs. Basing on an earlier proposition, the catalysis of ORR by MWCNTs in RTILs is discussed.
Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 9, pp. 1137–1146.
The text was submitted by the authors in English. 相似文献
87.
Debojyoti Lahiri Tuhin Bhowmick Bhabatosh Banik Reema Railkar Suryanarayanarao Ramakumar Rajan R. Dighe Akhil R. Chakravarty 《Polyhedron》2010
Dicobalt(II) complexes [{(B)CoII}2(μ-dtdp)2] (1–3) of 3,3′-dithiodipropionic acid (dtdp) and phenanthroline bases (B), viz. 1,10-phenanthroline (phen in 1), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq in 2) and dipyrido[3,2-a:2′,3′-c]phenazine (dppz in 3), have been prepared, characterized and their photo-induced anaerobic DNA cleavage activity studied. The elemental analysis and mass spectral data suggest binuclear formulation of the complexes. The redox inactive complexes have magnetically non-interacting dicobalt(II) core showing magnetic moment of ∼3.9 μB per cobalt(II) center. The complexes show good binding propensity to calf thymus DNA giving Kb values within 4.3 × 105–4.0 × 106 M−1. Thermal melting and viscosity data predict DNA groove binding and/or partial intercalative nature of the complexes. The complexes show significant anaerobic DNA cleavage activity in green light under argon atmosphere possibly involving radical species generated from the disulfide moiety in a type-I pathway. The DNA cleavage reaction under aerobic medium in green light is found to involve hydroxyl radical species. The dppz complex 3 exhibits significant photocytotoxicity in HeLa cervical cancer cells with an IC50 value of 2.3 μM in UV-A light of 365 nm, while it is essentially non-toxic in dark giving an IC50 value of >200 μM. A significant reduction of the dark toxicity of the organic dppz base (IC50 = 8.3 μM in dark) is observed on binding to the cobalt(II) center while essentially retaining its photocytotoxicity in UV-A light (IC50 = 0.4 μM). 相似文献
88.
Cuirong Sun Jindi Fu Juanjuan Chen Liyan Jiang Yuanjiang Pan 《Journal of separation science》2010,33(8):1018-1023
A practical approach for rapidly screening antioxidants against superoxide anion radicals from complex mixtures was developed based on the quantitative difference in active compounds before and after their reaction. To test the effectiveness of the approach, seven flavonoids with antioxidative properties were investigated both individually and in a mixture. Using the approach, antioxidants could be rapidly separated and screened with a ranked order of activities in the meantime. The radical scavenging activities were in the following order: quercetin > kaempferol > fisetin > puerarin > luteolin > rutin > baicalein. The order of activity was conducted by comparing the scavenging ratio of the antioxidant, which was completely consistent with the results obtained from the traditional electronic spin resonance. Then, the method was successfully applied to black tea extracts. This approach is fast and convenient for screening, isolating, and analyzing potential antioxidants from a mixture with good quantitative and reproducible ability. 相似文献
89.
Hanane Zejli Jose Luis Hidalgo-Hidalgo de Cisneros Khalid Riffi Temsamani 《Talanta》2010,80(5):1805-1808
The Sonogel electrode was immersed in hemin solution to obtain the hemin-Sonogel-modified electrode by cyclic voltammetry (CV). It was applied to detect superoxide radicals produced by xanthine oxidase catalyzed hypoxanthine oxidation. The characterization of hemin-Sonogel was modified by impedance and CV. 相似文献
90.