拓展城市功能促进农村发展

<正> 几年来,各地都开展农业产业结构调整,根据各自条件,努力建立适应市场需求,促进农民增收和农村经济发展的农业结构新格局。然而,农村人口占全国人口70％,约70％农村劳动力从事初级农业生产,有限的农业经济资源潜力难以从根本上改变农村经济发展缓慢和农民收入较低的局面。随着我国加入世贸组织,农业面临来自国际市场更大的压力和挑战,只对

一氧化氮是脱落酸诱导杨树叶片气孔关闭的信号分子

研究了外源NO和ABA对杨树气孔运动调节作用 .结果表明 ,外源NO和ABA都能诱导杨树离体叶片气孔关闭 ,且具有剂量效应 ,NO可加强ABA诱导气孔关闭的作用 .NO清除剂 (c PTIO)可大大减弱NO和ABA对气孔关闭的诱导作用 .证实了NO参与ABA调控气孔开闭运动过程 ,不同浓度NO供体SNP和ABA处理杨树离体叶片 ,SOD活性变化不明显 ,POD活性受到显著抑制 .杨树叶片粗酶液的体外实验表明 ,不同浓度SNP对POD活性的抑制呈明显的浓度及时间效应 ;而ABA对POD活性则几乎没有影响 .本研究证明 ,NO调节ABA诱导的树木气孔关闭作用 ,是ABA诱导树木气孔关闭的一种重要信号分子 .

Influence of the deposition energy on the composition and thermal cycling behavior of La-2(Zr0.7Ce0.3)(2)O-7 coatings

Lanthanum-zirconium-cerium composite oxide (La-2(Zr0.7Ce0.3)(2)O-7, LZ7C3) coatings were prepared under different conditions by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphologies, cyclic oxidation behavior of these coatings were studied. Elemental analysis indicates that the coating composition has partially deviated from the stoichiometry of the ingot, and the existence of excess La2O3 is also observed.

Sensitive, Label-Free Protein Assay Using 1-ethyl-3-methylimidazolium Tetrafluoroborate Supported Microchip Electrophoresis with Laser-Induced Fluorescence Detection

Based on the dimer-monomer equilibrium movement of the fluorescent dye Pyronin Y (PY), a rapid, simple, highly sensitive, label-free method for protein detection was developed by microchip electrophoresis with LIF detection. PY formed a nonfluorescent dimer induced by the premicellar aggregation of an anionic surfactant, SDS, however, the fluorescence intensity of the system increased dramatically when proteins such as BSA, bovine hemoglobin, cytochrome c, and trypsin were added to the solution due to the transition of dimer to fluorescent monomer. Furthermore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF(4)) instead of PBS was applied as running buffers in microchip electrophoresis.

Novel aliphatic poly(ester-carhonate) with pendant allyl ester groups and its folic acid functionalization

A series of novel poly(ester-carbonate)s bearing pendant allyl ester groups P(LA-co-MAC)s were prepared by ring-opening copolymerization Of L-lactide (LA) and 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) with diethyl zinc (ZnEt2) as initiator. NMR analysis investigated the microstructure of the copolymer. DSC results indicated that the copolymers displayed a single glass-transition temperature (T-g), which was indicative of a random copolymer, and the Tg decreased with increasing carbonate content in the copolymer.

Improved Melting Strength of Polypropylene by Reactive Compounding With Ultrafine Full-Vulcanized Polybutadiene Rubber (UFBR) Particles

Ultrafine full-vulcanized polybutadiene rubber (UFBR) in particle sizes of ca. 50-100 nm has been used for modifying mechanical and processing performances of polypropylene (PP), and PP-g-maleic anhydride (PP-MA) has been used as a compatibilizer for enhancing the interfacial adhesion between the two components. The results show that PP/UFBR possesses rheological behaviors such as highly branched PP when UFBR content in blends reaches 10 wt%, while in contrast, the much low content of UFBR combining small amount of PP-MA endows the material with rheological characteristics of high melt strength materials like highly branched PP.

Spontaneous formation of two-dimensional gold networks at the air-water interface and their application in surface-enhanced Raman scattering (SERS)

Two-dimensional (2-D) gold networks were spontaneously formed at the air-water interface after HAuCl4 reacted with fructose at 90 degrees C in a sealed vessel, in a reaction in which fructose acted as both a reducing and a protecting agent. Through fine-tuning of the molar ratio of HAuCl4 to fructose, the thus-formed 2-D gold networks can be changed from a coalesced pattern to an interconnected pattern. In the coalesced pattern, some well-defined single-crystalline gold plates at the micrometer-scale could be seen, while in the interconnected pattern, many sub-micrometer particles and some irregular gold plates instead of well-defined gold plates appeared. It is also found that the 2-D gold networks in the form of an interconnected pattern can be used as substrates for surface-enhanced Raman scattering (SERS) because of the strong localized electromagnetic field produced by the gaps between the neighboring particles in the 2-D gold networks.

Preparation and optical properties of trivalent europium-doped bulk and nanocrystalline SrY2O4

The nanocrystalline Sry(2)O(4):Eu3+ was prepared by a poly(vinyl alcohol) (PVA)+glycine-assist combustion method. The results of x-ray diffraction indicate that the resulting Sry(2)O(4):Eu3+ nanocrystals have much broader and less intense peaks compared with those in bulk material. The charge-transfer bands in Sry(2)O(4):Eu3+ nanocrystals shift to higher energies in contrast to those in bulk material. The spectral results revealed that in bulk SrY2O4: Eu3+ the Eu3+ ions occupied three nonequivalent sites, with one at the Sr site: one at the Y(1) site and another at the Y(2) site, while in nanocrystalline SrY2O4: Eu3+, the Eu3+ ions occupied only two nonequivalent sites; one at the Y(1) site and the other at the Y(2) site. Finally, by theoretical calculation and analysis, the analyzed results are in reasonable agreement with our experimental results.

两亲性线性-超支化多臂共聚物在水溶液中自组装为阳离子囊泡的研究

利用两亲性线性-超支化多臂共聚物聚乙二醇-聚乙烯亚胺-聚谷氨酸苄酯(PEG-PEI-PBLG)在水溶液中自组装为阳离子囊泡.利用透射电镜、动态光散射、静态光散射和zeta电位仪对囊泡结构进行了表征.PEG-PEI-PBLG囊泡具有双分子层结构,壁厚5~10nm,直径在100nm左右.由于PEI在水溶液中的质子化作用,囊泡表面携带有正电荷,其表面电势为+25.2mV,因此PEG-PEI-PBLG阳离子囊泡具有担载负电性蛋白的能力.

The involvement of HSP22 from bay scallop Argopecten irradians in response to heavy metal stress

Heat shock protein 22 (HSP22) is an important member of small heat shock protein (sHSP) subfamily which plays a key role in the process of protecting cells, facilitating the folding of nascent peptides, and responding to stress. In the present study, the cDNA of HSP22 was cloned from Argopecten irradians (designated as AiHSP22) by rapid amplification cDNA end (RACE) based on the expressed sequence tags (ESTs). The full-length cDNA of AiHSP22 was of 1,112 bp, with an open reading frame of 588 bp encoding a polypeptide of 195 amino acids. The deduced amino acid sequence of AiHSP22 showed high similarity to previously identified HSP22s. The expression patterns of AiHSP22 mRNA in different tissues and in haemocytes of scallops exposed to Cd2+, Pb2+ or Cu2+ were investigated by real-time quantitative RT-PCR. The mRNA of AiHSP22 was constitutively expressed in all examined tissues, including haemocyte, muscle, kidney, gonad, gill and heart. The expression level in heart and muscle was higher than that in other tissues. The mRNA level of AiHSP22 in haemocytes was up-regulated after a 10 days exposure of scallops to Cu2+, Pb2+ and Cd2+. However, the expression of AiHSP22 did not increase linearly along with the rise of heavy metal concentration. Different concentrations of the same metal resulted in different effects on AiHSP22 expression. The sensitive response of AiHSP22 to Cu2+, Pb2+ and Cd2+ stress indicated that it could be developed as an indicator of exposure to heavy metals for the pollution monitoring programs in aquatic environment.

A simple and low-cost airlift photobioreactor for microalgal mass culture

A simple, low-cost, and efficient airlift photobioreactor for microalgal mass culture was designed and developed. The reactor was made of Plexiglas, and composed of three major parts: outer tube, draft tube and air duct. The fluid-dynamic characteristics of the airlift reactor were studied. The system proved to be well suited to the mass cultivation of a marine microalga, Chlorella sp. In batch culture, the biomass volumetric output rate of 0.21 g l(-1) d(-1) was obtained at the superficial gas velocity of 4 mm s(-1) in the draft tube.

Some palaemonid shrimps (Crustacea : Decapoda) from northern South China Sea, with descripitions of two new species

Thirty-four palaemonid species from the northern area of South China Sea are reported in the present paper, including two new species, Paranchistus lini, new species, and Periclimenes chacei, new species, and eight other species are reported for the first time from South China Sea: Leander tenuicornis (Say, 1818), Leandrites stenopus Holthuis, 1950, Palaemon debilis Dana, 1852, Urocaridella antonbrurnii (Bruce, 1967), Kemponia platycheles (Holthuis, 1952), Paraclimenes franklini (Bruce, 1990b), Paranchistus spondylis Suzuki, 1971, Periclimenes hirsutus Bruce, 1971.

The pontoniine shrimps (Crustacea : Decapoda : Palaemonidae) from Anambas and Natuna Islands, Indonesia, collected by Anambas Expedition, 2002

The present paper reports 8 pontoniine shrimp species, from Anambas and Natuna, Indonesia, i. e., Anchistus miersi (De Man, 1888), Conchodytes meleagrinae Peters, 1852, Hamodacotylus boschmai Holthuis, 1952, Jocaste japonica (Ortmann, 1890), Palaemonella pottsi (Borradaile, 1915), Periclimenes andamanensis Kemp, 1922, Periclimenes attenuatus Bruce, 1971, and Periclimenes grandis (Stimpson, 1860).

牦牛暖季放牧对牧草消化率的影响

通过垂穗披碱草-星星草混播草地连续3个放牧季的牦牛放牧试验,对不同放牧强度下牧草的消化率进行了研究.结果表明:放牧强度对牦牛所食牧草中酸性洗涤纤维消化率的影响极显著(P＜0.01),对粗纤维消化率的影响显著(P＜0.05),而对所食牧草中的总能、粗蛋白、粗灰分和中性洗涤纤维的影响不显著(P＞0.05);放牧时间对中性和酸性洗涤纤维的影响极显著(P＜0.01),而对牧草总能、粗蛋白、粗纤维和粗灰分的影响不显著(P＞0.05).尽管牦牛的采食量均随放牧强度的增加而减小,但牦牛对采食牧草各营养成分的消化率并未出现规律性变化.