土壤微生物ATP、脱氢酶和尿素酶活性的ED50值评价外源镧的生物毒性

０IntroductionRareearthsarenowappliedwidelyinChina，whichcanimprovecropsyieldsandthetheirqualit－ies犤１犦．Thebeneficialeffectsmaybeduetothestimu－latoryeffectsoftheseelementsonthenutrientuptakebyplantsorontheincreasingofchlorophyllsynthesisintheplants犤２犦．Whilealotofresearcheshavebeendoneontheimprovednutritionofcropsafterapplica－tionofrareearths，muchlessattentionhasbeenpaidtothedeteriorationofsoilqualityduetotheapplicationofrareearthsforyears犤３犦．Scientistshavediscoveredthataccumula…     

Tm3+/Yb3+共掺铋碲酸盐玻璃中的高效蓝色上转换荧光

制备了高折射率Tm3+/Yb3+共掺杂铋碲酸盐玻璃,利用棱镜耦合法测量出玻璃在632.8和1550 nm波长处的折射率分别为2.0365和1.9795. 对玻璃的吸收、荧光和红外透过光谱展开了测试与分析,根据Judd-Ofelt理论对吸收光谱进行拟合,求得Tm3+的振子强度参数Ωt(t=2,4,6)分别为3.90×10-20, 2.03×10-20和9.03×10-21 cm2,并进一步计算了Tm3+在玻璃中各能级跃迁的振子强度、自发辐射跃迁概率、辐射寿命和荧光分支比等光谱参数. 在980 nm激光激发下测得强的蓝色三光子上转换和近红外双光子上转换荧光. 宽的红外透过窗口、高的折射率和强的蓝色上转换荧光表明,Tm3+/Yb3+共掺铋碲酸盐玻璃有希望成为高效的上转换发光和激光材料.     

MONTE CARLO CALCULATION OF THE EFFICIENCIES OF THE LEAD GLASS DETECTORS FOR HIGH-ENERGY GAMMA RAYS

In this paper, the electromagnetic shower processes occured in the lead glass detector are simulated by the Monte Carlo method, the light collection effects being taken into account. The primary energy of gamma ray is from 8 to 30 MeV. The detected efficiency function, the energy resolution curve and photoelectron number distribution (the pulse-height spectra) are presented for the lead glass detector. The calculated results are satisfactory.     

A Study of Impacts of Global Sea Level Rise on Salt Water Intrusion Into the Changjiang Estuary

Using the methods of empirical correlation and numerical analogue computation of the longitudinal distribution of two-dimensional chlorinity and combined with the actual situation of water supply in the Changjiang Estuary, a calculation and analysis have been made in this paper of the impacts of sea level rise of 0.5—1.0 m in the Changjiang Estuary in the next century on the probabilities of hourly chlorinity of more than 100×10~(-6), 200×10~(-6) and 250×10~(-6) during the dry season st Wusong station and on the intrusion distance of the isohalines of 1×10~(-3) and 5×10~(-3) during the ebb tide stand of the dry season in the South Branch as well as on the longitudinal distribution of the chlorinity of the South Branch in the most unfavorable situation with the minimum monthly mean discharge during the special dry year.     

垫状卷柏的化学成分研究

从垫状卷柏分离纯化得到4个化合物;经波谱方法分别鉴定化合物结构为:β-谷甾醇(1),穗花杉双黄酮(2),24-乙基-胆甾-4-烯-3,6-二酮(3)[垫状卷柏胆甾酮(Pulvinatadione)]和5,5″,4″-三羟基-7,7″-二甲氧基-[4′-O-6″]双黄酮(4)[垫状卷柏双黄酮(Pulvinatabiflavone)],其中化合物3和4为新化合物.     

Synthesis,antifungal activity and 3D-QSAR study of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring

Molecular Diversity - A series of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring were designed and synthesized by multi-step reactions in search of novel antifungal...     

A new pyrrole alkaloid from Selaginella moellendorfii Hieron

One new pyrrole alkaloid,N-（2E）-3-（3,4-dihydrophenyl）prop-N₁-（4-aminoburyl）-3-pyrrole formaldehyde （1）,was isolated from the whole herbs of Selaginella moellendorfii Hieron.The structure was elucidated by spectroscopic analyses including UV,1R,1D NMR,2D NMR and MS methods.Additionally, compound 1 exhibited potent protective effect against the injury of human umbilical vein endothelial cell（HUVECs） induced by high concentrations of glucose in vitro.     

Synthesis,Antifungal Activity,and 3D-QSAR Study of Novel Nopol-Derived 1,3,4-Thiadiazole-Thiourea Compounds

A series of novel nopol derivatives bearing the 1,3,4-thiadiazole-thiourea moiety were designed and synthesized by multi-step reactions in search of potent natural product-based antifungal agents. Their structures were confirmed by FT-IR, NMR, ESI-MS, and elemental analysis. Antifungal activity of the target compounds was preliminarily evaluated by in vitro methods against Fusarium oxysporum f. sp. cucumerinum, Cercospora arachidicola, Physalospora piricola, Alternaria solani, Gibberella zeae, Rhizoeotnia solani, Bipolaris maydis, and Colleterichum orbicalare at 50 µg/mL. All the target compounds exhibited better antifungal activity against P. piricola, C. arachidicola, and A. solani. Compound 6j (R = m, p-Cl Ph) showed the best broad-spectrum antifungal activity against all the tested fungi. Compounds 6c (R = m-Me Ph), 6q (R = i-Pr), and 6i (R = p-Cl Ph) had inhibition rates of 86.1%, 86.1%, and 80.2%, respectively, against P. piricola, much better than that of the positive control chlorothalonil. Moreover, compounds 6h (R = m-Cl Ph) and 6n (R = o-CF₃ Ph) held inhibition rates of 80.6% and 79.0% against C. arachidicola and G. zeae, respectively, much better than that of the commercial fungicide chlorothalonil. In order to design more effective antifungal compounds against A. solani, analysis of the three-dimensional quantitative structure–activity relationship (3D-QSAR) was carried out using the CoMFA method, and a reasonable and effective 3D-QSAR model (r² = 0.992, q² = 0.753) has been established. Furthermore, some intriguing structure–activity relationships were found and are discussed by theoretical calculation.     

Bioactive compounds from Selaginella involven Spring that protect PC-12 cells

Two new compounds named as 3b 12 16-trihydroxy-6 8 11 13-abietatrien（1） （8R 80S）-4 40 8-trihydroxyl-3 30-dimethoxyl-90-lignanolide（2） and a new natural product 4 40-dihydroxyl-3 30 5 50-dimethoxyldiphenyl diketone（3） were isolated from the whole herbs of Selaginella involven Spring.The structures were elucidated by spectroscopic analyses including UV,IR,1D,2D NMR and MS methods.Additionally,these three compounds exhibited potent protective effect against the injury of PC-12 cells induced by hypoxia/reoxygenation.     

Tm3+/Yb3+共掺铋碲酸盐玻璃中的高效蓝色上转换荧光

制备了高折射率Tm³⁺/Yb³⁺共掺杂铋碲酸盐玻璃，利用棱镜耦合法测量出玻璃在632.8和1550nm波长处的折射率分别为2.0365和1.9795. 对玻璃的吸收、荧光和红外透过光谱展开了测试与分析，根据Judd-Ofelt理论对吸收光谱进行拟合，求得Tm³⁺的振子强度参数Ω_t(t=2，4，6)分别为3.90×10^-20, 2.03×10^-20和9.03×10^{-2 关键词： 3+}/Yb³⁺共掺')" href="#">Tm³⁺/Yb³⁺共掺 铋碲酸盐玻璃 光谱参数 上转换荧光