陕西省长武县土地利用变化的生态环境效应评价

通过对1988年9月15日的TM遥感影像、2000年5月19日的ETM遥感影像和2006年7月7日的ETM遥感影像解译,获取了长武县的土地利用图,根据中国陆地生态系统单位面积生态服务价值,求算出长武县的生态系统服务价值。结果表明:30年来,长武县的耕地面积随着"退耕还林"工程的推进有显著下降,林地面积则随着三北防护林建设工程的实施显著增加,未利用土地、水域和草地面积变化不大;长武县总体生态系统服务价值总量在逐年递增,从1988年的5.67×108元上升到2006年的5.72×108元,生态系统总体向健康方向发展。

施肥进步在粮食增产中的贡献及其地理分异

根据三个地点中长期田间试验联网研究发现 ,施肥在作物产量形成中的贡献受施肥制度和气候的热量因子所影响 ,在最佳施肥条件下 ,施肥在产量中的贡献率分别为海伦 (温带 ) 0 .31,沈阳 (暖温带 )0 .39和桃源 (亚热带 ) 0 .4 2 ,存在明显的地理分异现象 .由此可以得出 ,当其他技术条件不变时 ,施肥在产量中的贡献率最高可达 30 %～ 4 5 % ,随所在地区气候的热量条件而不同 .通过对施肥与气候热量之间的交互影响研究还发现 ,沈阳与桃源间的交互影响远大于海伦与沈阳之间 ,有机肥与气候热量之间的交互影响大于化肥与热量之间的交互影响

影响油脂茴香胺值和过氧化值的因素

<正>油脂氧化的最初产物是氢过氧化物,其数量可用测定碘化钾与它作用放出的游离碘多少而定量,每千克油脂所产生的碘的毫克当量数即该油的过氧化值,它是测量油脂最初氧化程度的指标。

中国革菌一新记录种——哈氏杯革菌

<正>2005年8月,作者对北京市的松山自然保护区的木材腐朽菌进行了考察,采集了大型真菌100余号,并对这些标本进行了鉴定。研究发现一种生长在阔叶林下的革菌为哈氏杯革菌Cotylidia harmandii (Lloyd)D．A．Reid。杯革菌属(Cotylidia P．Karst)

中国纤孔菌属两新记录种

本文报道了中国纤孔菌属两个新记录种,分别为芮克纤孔菌Inonotus rickii (Pat.) D.A.Reid和杨生纤孔菌Inonotus plorans (Pat.) Bondartsev & Singer。芮克纤孔菌采于海南省保亭县热带植物园,生长在橡胶树上,杨生纤孔菌Inonotus plorans发现于中国西北地区的新疆,生长在杨树上,本文根据中国的材料对这两个种进行了详细描述和显微结构绘图。

Studies on charge transfer across the micro-liquid/liquid interface supported at a double-barrel micropipette

In this paper, the charge transfer across the micro-liquid/liquid interface supported at the orifice of a double-barrel micropipette, namely, a theta-pipette, is reported. Simple ion transfer(TMA(+)), facilitated ion transfer (potassium ion transfer facilitated by DB18C6), and electron transfer (ferrocene and ferri/ferrocyanide system) have been investigated by cyclic voltammetry. The experimental results show that a very thin aqueous film, linking both barrels filled with the aqueous solution and the organic solution respectively, can spontaneously be formed on the outer glass surface of such a double-barrel micropipette to construct a micro-liquid/liquid interface, which provides the asymmetry of diffusion field. Such device is demonstrated experimentally which can be employed as one of the simplest electrochemical cells to investigate the charge transfer across the liquid/liquid interface.

Morphology, structure, and properties of in situ compatibilized linear low-density polyethylene/polystyrene and linear low-density polyethylene/high-impact polystyrene blends

Blends of linear low-density polyethylene (LLDPE) with polystyrene (PS) and blends of LLDPE with high-impact polystyrene (HIPS) were prepared through a reactive extrusion method. For increased compatibility of the two blending components, a Lewis acid catalyst, aluminum chloride (AlCl3), was adopted to initiate the Friedel-Crafts alkylation reaction between the blending components. Spectra data from Raman spectra of the LLDPE/PS/AlCl3 blends extracted with tetrahydrofuran verified that LLDPE segments were grafted to the para position of the benzene rings of PS, and this confirmed the graft structure of the Friedel-Crafts reaction between the polyolefin and PS. Because the in situ generated LLDPE-g-PS and LLDPE-g-HIPS copolymers acted as compatibilizers in the relative blending systems, the mechanical properties of the LLDPE/PS and LLDPE/HIPS blending systems were greatly improved. For example, after compatibilization, the Izod impact strength of an LLDPE/PS blend (80/20 w/w) was increased from 88.5 to 401.6 J/m, and its elongation at break increased from 370 to 790%. For an LLDPE/HIPS (60/40 w/w) blend, its Charpy impact strength was increased from 284.2 to 495.8 kJ/m(2). Scanning electron microscopy micrographs showed that the size of the domains decreased from 4-5 to less than 1 mum, depending on the content of added AlCl3.

Arabinogalactan as a carrier for contrast agent in magnetic resonance imaging

Arabinogalactan-Gd-DTPA was synthesized by the reaction of diethylenetriaminepenta-acetic acid (DTPA) bisanhydride with polysaccharide in dry DMSO and characterized by FTIR, elemental analysis and ICP-AES. Its stability was investigated by competition with Ca2+, EDTA, DTPA. The t(1)-relaxivity is 8.06 mmol(-1) . L . s(-1) in D2O, 8.48 mmol(-1) . L . s(-1) in 0.725 mmol . L-1 BSA, respectively. t(1)-weighted MR imaging of rat kidney and liver showed a remarkable enhancement post injection of Arabinogalactan-Gd-DTPA. The results indicate that the arabinogalactan-Gd-DTPA is a potential contrast agent for MRI.

以阿拉伯半乳聚糖为载体的磁共振成像造影剂的研究

合成了阿拉伯半乳聚糖修饰的 DTPA钆配合物 ,用红外光谱、元素分析、 ICP-AES等手段进行了表征 ,用竞争性方法研究了其在水溶液中的稳定性 ,测试了其在水中及 BSA溶液中的弛豫性能 ,并进行了体内成像实验 .结果表明 ,其弛豫效率是目前临床所用造影剂 Gd-DTPA的 1 .5～ 2 .0倍 ,对肝脏和肾脏 MRI信号具有良好的增强效果 ,是比较好的潜在磁共振成像造影剂

P-6(7/2)-excited-state decay mechanism and energy-transfer processes in KMgF3 : Eu2+ and KMgF3 : EuX (X = Gd, Ce, Cr)

A four-level decay model in KMgF3:Eu2+ is proposed. The decay profiles of the P-6(7/2) excited state of Eu2+ are biexponential, and the physical implication of each term in the fit equation responsible for the model is interpreted. The evidence obtained spectroscopically for supporting the model is presented. A new method to study energy transfer between Eu2+ and X3+ in KMgF3:Eu-X (X = Gd, Ce, Cr) is established on the basis of the proposed model.

Study of energy transfer in KMgF3 : Eu-X (X = Gd, Cr, Ce) by the decay model of P-6(7/2) exited state of Eu2+

Energy transfer processes between Eu2+ and Gd3+, Cr3+, Ce3+ ions in KMgF3, which are difficult to study spectroscopically, have been investigated by using the proposed four-level decay model of the P-6(7/2) excited state of the Eu2+ ion. Gd3+ and Ce3+ transfer its energy to the vibronic transition of the P-6(7/2) --> S-8(7/2) transition of Eu2+, whereas Cr3+ receive energy from Eu2+ via the d-d interaction. The energy transfer from the Eu2+ 4f(6)5d level to the Ce3+ 4f5d state is observed spectroscopically, and the energy transfer mechanism is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Luminescence of RE2+ (RE = Sm, Yb) in barium octoborate

The reduction process from trivalent to divalent state for Sm3+ and Yb3+ ions in barium berates (BaB8O13) prepared in air was observed. The luminescence properties of these divalent rare-earth ions were studied. Yb2+ shows an f-d broad emission band, due to the 4f(14) --> 4f(13)5d transition, while the Sm2+ ion shows an f --> f transition. From the spectra of Yb2+, and using the D-5(0) --> F-7(0) transition of Sm2+ as a structural probe, two crystallographic sites were found to be available for the cations in the host. Vibronic transitions of Sm2+ were observed at low temperature. BaB8O13 was found to be a good host for reducing the trivalent rare-earth ions to divalent state and to exhibit interesting spectroscopic properties,

Interaction of scopolamine and cholesterol with sphingomyelin bilayers by FT-Raman spectroscopy

The interaction of scopolamine and cholesterol with sphingomyelin bilayers has been investigated by FT-Raman spectroscopy in head-group region (600-1000 cm(-1)), the C-C stretching (1000-1200 cm(-1)), CH2 deformation (1400-1500 cm(-1)) and the C-H stretching (2800-3000 cm(-1)) mode regions. The results indicate that scopolamine and cholesterol do not change the conformation of O-C-C-N+ backbone in the choline group of sphingomyelin bilayers, the polar headgroup is still extending parallel to the bilayer surface and O-C-C-N+ group is still in its gauche conformer. Scopolamine and cholesterol lower the order of the interface, the interchain, CH2 crystal lattices and the lateral chain-chain packing, and increase their fluidity.

Two-step-method extraction of endohedral metallofullerenes

A new and efficient extraction method of endohedral metallofullerenes, especially of rare-earth elements encapsulated metallofullerenes, has been reported in this paper. Soxhlet-extraction of raw soot with toluene was used in the first step to wash away most accompanying C-60, C-70. Then pyridine was chosen as solvent to obtain high-temperature and high pressure extract. Two kinds of extract were analysed by DEI-MS and LDI-MS, the results indicate that this two-step method can provide the extract which has the highest fraction of endohedral metallofullerenes. So it will greatly simplify the following separation and purification processes of metallofullerenes.

两步法提取笼内金属富勒烯

两步法提取笼内金属富勒烯郝春雁，刘子阳，徐文国，郭兴华，刘淑莹（中国科学院长春应用化学研究所，吉林大学化学系，长春，１３００２２）关键词金属富勒烯，索氏提取，ＤＥＩ－ＭＳ，ＬＤＩ－ＭＳ目前笼内包含金属的富勒烯化合物以其新颖独特的结构和性质而格外引人注...