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排序方式: 共有248条查询结果,搜索用时 46 毫秒
1.
0IntroductionRareearthsarenowappliedwidelyinChina,whichcanimprovecropsyieldsandthetheirqualit-ies犤1犦.Thebeneficialeffectsmaybeduetothestimu-latoryeffectsoftheseelementsonthenutrientuptakebyplantsorontheincreasingofchlorophyllsynthesisintheplants犤2犦.Whilealotofresearcheshavebeendoneontheimprovednutritionofcropsafterapplica-tionofrareearths,muchlessattentionhasbeenpaidtothedeteriorationofsoilqualityduetotheapplicationofrareearthsforyears犤3犦.Scientistshavediscoveredthataccumula… 相似文献
2.
The review considers problems related to the formation, in the living organism, of nitric oxide, a versatile and vitally important regulator of cell metabolism. The pathways of formation of endogenous nitric oxide from L-arginine are discussed and the main approaches to increasing the NO concentration by introducing various types of exogenous nitric oxide donors into the organism and chemical and biological characteristics of these donors are considered. Primary attention is devoted to the known drugs that were shown to release NO under hydrolytic, oxidative, or reductive conditions. The solution of problems related to the elucidation of the mechanisms of drug action requires that the formation of nitric oxide be taken into account. 相似文献
3.
2型糖尿病患者血清钙镁与甲状腺激素含量变化及临床意义 总被引:1,自引:0,他引:1
为了监测 2型糖尿病人血清钙、镁和甲状腺激素含量 ,分析其临床意义及相关性 ,应用放射免疫分析法测定了 1 1 5例 2型糖尿病及 1 5 0例健康人血清甲状腺激素含量。同时用美国杜邦RXL自动生化仪测定了其血清钙、镁含量。结果表明 ,在 2型糖尿病伴有明显并发症者血镁、FT3水平明显降低 (P <0 0 5 ) ,钙镁两种元素与甲状腺激素水平无明显相关性。 2型糖尿病患者适当补镁对预防其并发症是有益的 ,测定FT3 等可作为判断 2型糖尿病严重程度和估计预后的参考指标。 相似文献
4.
Thermodynamics of the interaction between Ni2+ and human growth hormone (hGH) were determined at 27 °C in Nail solution by isothermal titration calorimetry. A new method to predict protein penetration and the effect of metal ions on the stability of proteins is introduced. The new solvation model was used to reproduce the enthalpies of Ni2+-hGH interaction over the whole range of Ni2+ concentrations. The solvation parameters recovered from the new equation, attributed to the structural change of hGH and its biological activity. 相似文献
5.
E. Wünsch G. Wendlberger W. Göhring G. Hübener B. Traving 《Monatshefte für Chemie / Chemical Monthly》1993,124(5):577-586
Summary The synthesis of the heptacosapeptide amide with the primary structure of Human-secretin is described. For this purpose 7 fragments were designed, i.e. H-Gly-Leu-Val-NH2 25–27b,Z-Arg(Z
2)-Leu-Leu-Gln-OH 21–24,Z-Arg(Z
2)-Leu-Gln-OH 18–20,Z-Arg(Z
2)-Glu(OtBu)-Gly-Ala-OH 14–17,Z-Arg(Z
2)-Leu-OH 12–13,Z-Thr(tBu)-Ser(tBu)-Glu(OtBu)-Leu-Ser(tBu)-OH 7–11,Adoc-His(Adoc)-Ser(tBu)-Asp(OtBu)-Gly-Thr(tBu)-Phe-OH 1–6 these fragments were consequently assembled to the overall protected total sequence using the Wünsch/Weygand-method with dicyclohexylcarbodiimide. After deprotection by exposure to trifluoroacetic acid in presence of 1,2-ethanedithiol and water as scavenger, the isolated crude product was purified by column chromatography on CM-Sepharose, fast flow. This synthetized Human-secretin showed the full biological activity in comparison to Porcine-secretin.
Herrn Prof. Dr. E. Bayer zum 65. Geburtstag gewidmet. 相似文献
6.
CHENG Peng YAN Shi-Ping LIAO Dai-Zheng BAI Ling-Jun JIANG Zong-Hui WANG Geng-LinDepartment of Chemistry Nankai Uviversity Tianjin China 《中国化学》1994,12(4):314-320
The syntheses and magnetic properties are reported for a series of copper(Ⅱ) complexes prepared from a pentadentate binucleating ligand 2,6-diformyl-4-methylphenol di(benzoyl-hydrazone) (H3L). These complexes incorporate different exogenous ions (X-) into a bridging position to form copper(Ⅱ) binuclear complexes of the formula [Cu2(H2L)X]2+, where X-= Br-(1), Cl-(2), HO-(3), C2H5O-(4) and C3H3N2- (5). The complexes have been characterized with variable temperature magnetic susceptibility (4.2-300 K) and the observed data were fit to those from a modified Bleaney-Bowers equation by least-squares method, giving the exchange integral 2J = -6.2 cm-1 for 1, -76.4 cm-1 for 2, -241.9 cm-1 for 3, -231.1 cm-1 for 4 and -343.8 cm-1 for 5. This suggested that there is an antiferromagnetic interaction between the Cu(Ⅱ) ions and the sequence of the effect of some exogenous bridging ligands on magnetic coupling is corresponding to that in spectrochemical series. 相似文献
7.
Bustamante JJ Garcia M Gonzalez L Garcia J Flores R Aguilar RM Trevino A Benavides L Martinez AO Haro LS 《Electrophoresis》2005,26(23):4389-4395
A method for separating proteins with a molecular mass difference of 2 kDa using SDS-PAGE under nonreducing conditions is presented. A sample mixture containing several human growth hormone (hGH) isoforms was initially separated on a weak anion-exchange column. Fractions rich in 24 kDa hGH as determined by analytical SDS-PAGE were pooled and further separated by cation-exchange chromatography. The fractions pooled from the cation-exchange chromatography contained two hGH isoforms with a 2 kDa molecular mass difference according to SDS-PAGE analysis, 22 and 24 kDa hGH. The 22 and 24 kDa hGH were separated using continuous-elution preparative double-inverted gradient PAGE (PDG-PAGE) under nonreducing conditions. The preparative electrophoresis gel was composed of three stacked tubular polyacrylamide matrices, a 4% stacking gel, a 13-18% linear gradient gel, and a 15-10% linear inverted gradient gel. Fractions containing purified 24 kDa hGH were pooled and Western blot analysis displayed immunoreactivity to antihGH antibodies. PDG-PAGE provides researchers with an electrophoretic technique to preparatively purify proteins under nonreducing conditions with molecular mass differences of 2 kDa. 相似文献
8.
9.
Hermann Singer 《The Journal of mathematical sociology》2013,37(1):39-49
In a recent paper it was shown that the aliasing phenomenon, which leads to a severe identification problem in the estimation of stochastic differential equations, can be overcome by using a polygonal (or higher) approximation for the time paths of the exogenous variables. This work attempts to visualize the problem and presents several simulated trajectories of a continuous time AR(2)‐process (Ornstein‐Uhlenbeck‐process) together with the observationally equivalent structures. Furthermore it is shown that aliasing can even change the analytical properties of the time paths of the system: whereas the first component of the Ornstein‐Uhlenbeck‐process is differentiable, the trajectories of the aliasing structures are continuous, but not differentiable any more. 相似文献
10.
Amy Gravitte Timothy Archibald Allison Cobble Benjamin Kennard Stacy Brown 《Biomedical chromatography : BMC》2021,35(1)
Liquid chromatography, coupled with tandem mass spectrometry, presents a powerful tool for the quantification of the sex steroid hormones 17‐β estradiol, progesterone and testosterone from biological matrices. The importance of accurate quantification with these hormones, even at endogenous levels, has evolved with our understanding of the role these regulators play in human development, fertility and disease risk and manifestation. Routine monitoring of these analytes can be accomplished by immunoassay techniques, which face limitations on specificity and sensitivity, or using gas chromatography–mass spectrometry. LC–MS/MS is growing in capability and acceptance for clinically relevant quantification of sex steroid hormones in biological matrices and is able to overcome many of the limitations of immunoassays. Analyte specificity has improved through the use of novel derivatizing agents, and sensitivity has been refined through the use of high‐resolution chromatography and mass spectrometric technology. This review highlights these innovations, among others, in LC–MS/MS steroid hormone analysis captured in the literature over the last decade. 相似文献