甜高粱在青海高原种植的初步研究；Preliminary study on sweet sorghum growing on Qinghai Plateau

为探讨甜高粱(Sorghum bicolor)在青海作为饲料作物种植的可能性,在青海高原上做了初步试验,结果显示:密度对茎秆高度、茎粗、产量有显著影响,对生育期、单株质量影响不显著,株行距为0.40 m×0.20m时,产量最高;浇水次数对甜高粱的生育期、茎秆高度、茎粗、单株质量、产量没有显著影响,表明甜高粱对水分依赖不高,具有很强的耐旱和抗旱性;地膜对甜高粱有极显著影响,使其生育期提前,茎秆高度增高,单株质量增加、产量提高;糖分含量在开花-收获期为15.93%~16.67%,比不盖地膜增加了29.19%~47.98%;大田示范密度0.50 m×0.20 m,开花-收获期666.7 m2产量达4 890.8 kg,投入产出比为1∶1.78,效益显著。研究表明,在青海高原东部农业区盖地膜种植饲用甜高粱,用作饲料是完全可行的。

Two-stage photo-biological production of hydrogen by marine green alga Platymonas subcordiformis

A marine green alga, Platymonas subcordiformis, was demonstrated to photobiologically evolve hydrogen (H-2) after the first stage of photosynthesis, when subjected to a two-phase incubation protocol in a second stage of H2 production: anaerobic incubation in the dark followed by the exposure to light illumination. The anaerobic incubation induced hydrogenase activity to catalyse H? evolution in the following phase of light illumination. H,) evolution strongly depended upon the duration of anaerobic incubation, deprivation of sulphur (S) from the medium and the medium pH. An optimal anaerobic incubation period of 32 h gave the maximum H2 evolution in the second phase in the absence of sulphur. Evolution of H,) was greatly enhanced by 13 times when S was deprived from the medium. This result suggests that S plays a critical role in the mediation of H-2 evolution from R subcordiformis. A 14-fold increase in H-2 production was obtained when the medium pH increased from 5 to 8; with a sharp decline at pH above eight. H-2 evolution was enhanced by 30-50% when supplementing the optimal concentrations of 25 mM acetate and 37.5 mM glucose. (C) 2003 Elsevier B.V. All rights reserved.

大气CO_2增加对土壤脲酶、磷酸酶活性的影响

The response of soil urease and phosphatase activities at different rice growth stages to free air CO 2 enrichment (FACE) was studied. The results showed that comparing with the ambient atmospheric CO 2 concentration (370μmol·mol~ -1), FACE (570μmol·mol~ -1) significantly increased the urease activity of 0～5cm soil layer at the vigorous growth stage of rice, whole that of 5～10cm layer had no significant change during the whole growing season. Phosphatase activity of 0～5cm and 5～10cm soil layers significantly increased, and the peak increment was at the vigorous growth stage of rice.

黄土丘陵区几种林木茎干径向生长的日变化及其对环境因素的响应

利用树木径向生长仪研究了黄土丘陵区6年生油松(Pinus tabulaef ormis)、山杨(Populus davidiana)和辽东栎(Quercus liaotungensis)及林下灌木胡颓子(Elaegnus umbellata)4种林木整个生长季茎干的径向变化,发现4种林木的径向变化表现为膨胀收缩旋回增长的模式。在整个生长季中,山杨从5月到10月径向持续增长,增长时间最长;而油松和胡颓子的径向生长主要发生在7月份,从8月份开始其增长速率变缓;辽东栎在整个生长季节的径向生长最小。在整个生长季内,山杨径向增长了2.63 mm,胡颓子为0.64 mm,油松和辽东栎则分别为0.40 mm和0.26 mm。辽东栎日收缩量与膨胀量明显大于其他树种。通过对影响林木径向生长的15种环境因子进行主成分分析后,将主要环境因子归结为温度影响因子、湿度影响因子和降水影响因子3个主成分,并提取了影响该区几种林木生长的主要环境因子:日大于0℃的积温、最低6 h相对湿度和日降雨量。采用线性逐步回归方法,建立了日膨胀量与日收缩量与3个主要环境因子之间的关系。发现日收缩量与日大于0℃的积温成正相关,而与最低6 h相对湿度和日降雨...

地下滴灌埋管深度对冬小麦根冠生长及水分利用效率的影响

在试验室内 ,进行了地下滴灌埋管深度对不同生育时期冬小麦根系生长和地上部分生长影响的试验研究。结果表明 :2 0 cm和 4 0 cm埋管深度的水分分布特征 ,在生育早期抑制地上部分营养生长 ,促进冬小麦蹲苗 ;而中后期则促进生殖生长 ,产量和水分利用效率较高。不考虑犁底层影响时 ,在重壤土上 4 0 cm是冬小麦进行地下滴灌的较好埋深

Structural characterization and identification of dibenzocyclooctadiene lignans in Fructus Schisandrae using electrospray ionization ion trap multiple-stage tandem mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance multiple-stage tandem mass spectrometry

The electrospray ionization ion trap multiple-stage tandem mass spectrometry (ESI-MSn) and electrospray ionization Fourier transform ion cyclotron resonance multiple-stage tandem mass spectrometry (ESI-FT-ICR-MSn) have been applied successfully to the direct investigation of a number of dibenzocyclooctadiene lignan constituents from the methanol extracts of the Fructus Schisandrae in the positive ion mode. The detailed structural characterization of the same skeleton and different peripheral substituents had been studied and the precise elemental compositions of ions at high mass resolution had been obtained. So the fragmentation mechanisms could be clarified.

Analysis of Saponins from Leaves of Aralia elata by Liquid Chromatography and Multi-stage Tandem Mass Spectrometry

Four saponins were isolated from the leaves of Aralia elata, and established using NMR and other spectroscopic methods, as well as data reported in the literature. Three Aralia saponins from the leaves of Aralia elata sharing the same structures as those isolated from the root bark suggested that the leaves would be a good substitute for the root bark of Aralia elata. These four Aralia saponins were then extensively investigated using complementarily positive and negative electrospray ionization multistage tandem mass spectrometry (ESI-MSn). Two isomers of saponins with different sugar linkages were then successfully differentiated by positive ESI-MSn and verified with different retention times and the collision-induced dissociation (CID) spectra by LC-MS. A simple and effective LC-MS method was thus developed for the rapid identification and screening of these saponins in plant extracts from leaves of Aralia elata.

Studies on principal components and antioxidant activity of different Radix Astragali samples using high-performance liquid chromatography/electrospray ionization multiple-stage tandem mass spectrometry

The principal components, isoflavonoids and astragalosides, in the extract of Radix Astragali were detected by a high-performance liquid chromatography Couple to electrospray ionization ion trap multiple-stage tandem mass spectrometry (HPLC-ESI-IT-MSn) method. By comparing the retention time (t(R)) of HPLC, the ESI-MSn data and the structures of analyzed Compounds with the data of reference compounds and in the literature, 17 isoflavonoids and 12 astragalosides have been identified or tentatively deduced. By Virtue of the extracted ion chromatogram (EIC) mode, simultaneous determination of isoflavonoids and astragalosides could be achieved when the different components formed overlapped peaks. And this method has been utilized to analyze the constituents in extracts of Radix Astragali from Helong City and of different growth years. Then the antioxidant activity of different samples has been Successfully investigated by HPLC-ESI-MS method in multiple selected ion monitoring(MIM) mode, applying the spin trapping technology, and the Ferric Reducing Antioxidant Power (FRAP) assay was applied to support the result.

Studies on lignan constituents from Schisandra chinensis (Turcz.) Baill. fruits using high-performance liquid chromatography/electrospray ionization multiple-stage tandem mass spectrometry

A reversed-phase high-performance liquid chromatography-diode array detector-electrospray ionization multiple-stage tandem mass spectrometry (RP-HPLC-DAD-ESl-MSn) method has been developed for the detection and analysis of lignan constituents in the methanol extract from the fruits of Schisandra chinensis (Turcz.) Baill. RP-HPLC-DAD-ESI-MSn and electrospray ionization Fourier transform ion cyclotron resonance multiple-stage tandem mass spectrometry (ESI-FT-TCR-MSn) have been applied to investigate the characteristic product ions of four lignan reference compounds. Then, the logical fragmentation pathways of the lignans have been proposed. By comparing the retention time (t(R)) of HPLC, the ESI-MSn data and the structures of analyzed compounds with the data of reference compounds and in the literature, 11 peaks in HPLC have been unambiguously identified and another 5 peaks have been tentatively identified or deduced. Also, in the present paper, the extracted ion chromatograms (EIC) have been used to analyze the lignan isomers. The experimental results demonstrate that RP-HPLC-DAD-ESI-MSn is a specific and useful method for the identification of the lignan constituents and their isomers.

Hole nucleation and growth induced by crystallization and microphase separation of thin semicrystalline diblock copolymer films

We have investigated the hole nucleation and growth induced by crystallization of thin crystalline-coil diblock copolymer films. Semicrystalline rodlike assemblies from neutral/selective binary solvent are used as seeds to nucleate crystallization at temperatures above the glass transition temperature (T-g) but below melting point (T-m). The crystallization of nanorods drives neighboring copolymer chains to diffuse into the growing nanorods. Depletion of copolymer chains yields hole nucleation and growth at the edge of the nanorods. Simultaneously, the polymer chains unassociated into the nanorods were oriented by induction from the free surface and the substrate, leading to limitation of the hole depth to the lamellar spacing, similar to20 nm. The holes, as well as the nanorods, grow as t(alpha), where t is the annealing time and a crossover in the exponent a. is found. The orientation and stretching of the copolymer chains by the surface and interface are believed to accelerate the crystallization, and in turn, the latter accelerates the growth rate of the holes. At T > T-m, the grains melt and the copolymer chains relax and flow into the first layer of the film.

Multiple-stage tandem mass spectrometry for differentiation of isomeric saponins

Four isomers of steroidal saponins were differentiated using multiple-stage tandem mass spectrometry combined with electrospray ionization (ESI-MSn). With the addition of lithium salt, the [M+Li](+) ions of saponins were observed in the ESI spectra. MSn spectra of these [M+Li](+) ions provided detailed structural information and allowed differentiation of the four isomeric saponins. The cross-ring cleavage ions from the saccharide chains of the saponins could be used as diagnostic ions for information concerning the linkage of the sugar moieties of the saponins. The masses of the X, A, Y and C type fragment ions formed from [M+Li](+) ions of the isomeric saponins provided information defining the methyl group locations.