共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
高分子材料在控缓释化肥中的应用与发展前景 总被引:2,自引:0,他引:2
《高分子学报》2015,(9)
化肥已经广泛应用在农牧和园艺业等领域,目前全世界每年化肥的使用量高达4×108吨.然而,现有的化肥在应用中具有明显的应用缺陷及带来环境污染等问题,例如在干旱土壤中不能完全释放,引起土壤退化;此外,自然界中的突降暴雨及不合理的灌溉也容易发生养分流失而导致河流污染.基于上述问题,控缓释化肥已经成为研究热点.本文从控缓体系的设计及机理等问题出发,介绍不同高分子材料包膜的制备技术及其特性.现有的控缓释载体多为非降解的高分子合成材料,如聚苯乙烯,聚乙烯等.寻找一种环保、廉价、可再生的控缓释化肥基材已成为本领域的研究热点.但环保型控缓释化肥,尤其是使用天然高分子材料的体系还大都停留在实验室阶段.另外,干旱缺水是制约我国农业发展和加速土地荒漠化的重要因素.因此使用高吸水聚合物,能赋予缓释载体吸水保水功能,不仅能增强缓释功能,而且对于干旱地区植物的营养和水分状况有良好的改善作用.在农业上使用吸水性聚合物对于改良土壤物理性质、促进种子发芽和出苗、提高幼苗的成活率、降低植物对灌溉的需要、提高养分利用率等多方面都很有潜力. 相似文献
3.
随着包膜肥料和包膜材料的不断发展,为满足更多农业生产环境的需求,环境响应包膜肥料引起了研究者们的广泛关注。环境响应性包膜肥料具有智能响应、缓控释的特点,能够根据施肥环境中特定的刺激信号如pH、温度、光照、磁场等作出响应,从而使包膜材料的物理或化学结构发生改变,进而控制肥料养分的释放速率。因此,环境响应性肥料的研发具有一定的现实意义。本文根据肥料的实际应用,对pH响应性包膜肥料、温度响应性包膜肥料、磁响应性包膜肥料的制备及效果进行了综述,基于环境响应性包膜肥料存在的问题及发展趋势进行了展望。 相似文献
4.
5.
6.
7.
综述扫描电子显微镜在缓释微球制剂表征中的重要应用. 采用扫描电子显微镜法对缓控释微球制剂进行表征, 采用自动颗粒粒形、粒径图像识别法对微球进行统计学分析, 对扫描电子显微镜在控释微球制剂研发过程中的4个广泛应用场景进行论证和总结. 缓控释微球制剂学是高度依赖结构学的制剂类型, 其性能和治疗功效很大程度上取决于微球的微观特性, 如结构、孔径等. 微球颗粒的尺寸及粒度分布、形状对药物释放起决定性作用. 扫描电子显微镜具有所见即所得的优势, 可以很直观的对微球颗粒的粒径、粒形以及表面粗糙情况进行快速评估. 由于微球制剂高药物载量的特点, 其批间一致性尤为重要, 科学的图像识别分析方法对批间一致性的评估具有重要应用价值. 结果表明, 扫描电子显微镜在微球的研发与生产控制中具有广泛的应用价值, 为此类型制剂的研发提供了先进的表征工具. 相似文献
8.
9.
新型功能单体分子印迹聚合物的研究进展 总被引:2,自引:0,他引:2
分子印迹聚合物是近年发展起来的新型重要分子识别材料,功能单体是其识别性能最重要的影响因素之一,因此,对新型功能单体分子印迹聚合物的研究越来越受重视.基于分子印迹聚合物在固相萃取、色谱柱分离、传感器等方面的应用,对新型功能单体分子印迹聚合物的研究进展进行了综述. 相似文献
10.
11.
Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection 总被引:2,自引:0,他引:2
Irakli MN Samanidou VF Biliaderis CG Papadoyannis IN 《Journal of separation science》2012,35(13):1603-1611
An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 μm) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples. 相似文献
12.
Anamarija Kovač Peić Martina Šrajer Gajdošik Kate Brilliant Helen Callanan Douglas C. Hixson Marija Begić Djuro Josić 《Electrophoresis》2021,42(12-13):1388-1398
To identify changes in extracellular vesicles (EVs) secreted by the liver following drug-induced liver injury (DILI), rats were treated with a subtoxic dose (500 mg/kg) of the analgesic drug, acetaminophen (APAP). EVs were collected by liver perfusion of sham and APAP-treated rats. Changes in EVs morphology were examined by transmission electron microscopic analysis of negatively stained vesicles. Results from morphometric analysis of EVs revealed striking differences in their size and distribution. Proteome composition of EVs collected by liver perfusion was determined by mass spectrometry using methods of sample preparation that enabled better detection of both highly hydrophobic proteins and proteins with complex post-translational modifications. The collection of EVs after liver perfusion is an approach that enables the isolation of EVs shed not only by isolated hepatocytes, but also by the entire complement of hepatic cells. EVs derived after DILI had a lower content of alpha-1-macroglobulin, ferritin, and members of cytochrome 450 family. Fibronectin, aminopeptidase N, metalloreductase STEAP4, integrin beta, and members of the annexin family were detected only in APAP-treated samples of EVs. These results show that the present approach can provide valuable insights into the response of the liver following drug-induced liver injury. 相似文献
13.
N. M. Popova L. A. Sokolova E. A. Marchenko L. N. Bobrova 《Reaction Kinetics and Catalysis Letters》1998,65(2):371-379
The effect of temperature on the adsorption/desorption of ammonia from the air mixture on the surface of commercial binary
V/Al and ternary Pd/V/Al, V(0.65 wt.%) /W(6.73 wt.%) /Ti and V(1.8 wt.%) /W(7.3 wt.%) /Ti de-NOx catalysts has been investigated by temperature-programmed desorption (TPD) method. The ability of the commercial catalysts
to adsorb ammonia in the most stable surface species was shown to correlate well with their suppression of the NH3 oxidation. 相似文献
14.
Ni(OAc)2结合吡啶和叔丁基过氧化氢(TBHP)实现了苄基C-H与苄基醇类化合物在温和条件下(80~90℃,O21 atm)的选择性催化分子氧氧化反应.研究了过氧化物添加剂,配体,溶剂和温度的影响,得到了优化的反应条件.在苄基C-H的氧化中显示了很高的酮/醇选择性.用ESR法进行了Ni(III)的检测,证实了反应机理.竞争实验说明羰基化合物的生成不是因为醇继续氧化.酮可被解释为过氧化氢中间体受金属催化分解的产物. 相似文献
15.
乳腺癌代谢物组模式特征发现方法及HPLC/M S/M S分析 总被引:11,自引:0,他引:11
提出一种基于单独最优特征组合和BP神经网络的代谢物组模式特征发现方法,并用其寻找到尿样中与乳腺癌最为相关的4种核苷,组成一组特异性检测参数.经HPLC/MS/MS联用法鉴定,它们是乳清酸核苷、1-甲酰化腺苷、S-腺苷-L-蛋氨酸及N2-甲酰化鸟苷.将这4种核苷作为输入变量,用BP神经分类网络建立乳腺癌诊断模型.留一法交叉验证和独立验证结果表明,该模型预测准确率达到90%以上. 相似文献
16.
Elucidation of the absolute configuration of rhizopine by chiral supercritical fluid chromatography and vibrational circular dichroism 下载免费PDF全文
Alain Krief Melissa Dunkle Masoud Bahar Patrick Bultinck Wouter Herrebout Pat Sandra 《Journal of separation science》2015,38(14):2545-2550
The absolute configuration of rhizopine, an opine‐like natural product present in nitrogen‐fixing nodules of alfalfa infected by rhizobia, is elucidated using a combination of state‐of‐the‐art analytical and semi‐preparative supercritical fluid chromatography and vibrational circular dichroism spectroscopy. A synthetic peracetylated racemate was fractionated into its enantiomers and subjected to absolute configuration analysis revealing that natural rhizopine exists as a single enantiomer. The stereochemistry of non‐derivatized natural rhizopine corresponds to (1R,2S,3R,4R,5S,6R)‐4‐amino‐6‐methoxycyclohexane‐1,2,3,5‐tetraol. 相似文献
17.
Feng Song Mengyuan Song Haibo Luo Mingkun Xie Xindi Wang Hao Dai Yiping Hou 《Electrophoresis》2021,42(19):1892-1899
Kyrgyz ethnic group is one of the nomads in China, with the majority in Xinjiang and a small part of them living in Heilongjiang province. Historically, they have went through five migrations westward due to the wars. The name “Kyrgyz” means 40 tribes, originating from the primary groups of Kyrgyz. However, it is a largely understudied population, especially from the Y chromosome. In this study, we used a previously validated high-resolution Y-chromosome single nucleotide polymorphisms (Y-SNPs) and short tandem repeats (Y-STRs) system to study Kyrgyz ethnic group. A total of 314 male samples of Kyrgyz ethnic group were genotyped by 173 Y-SNPs and 27 Y-STRs. After data analysis, the results unveiled that Kyrgyz ethnic group was a population with high percentage of both haplogroup C2a1a3a1d∼-F10091 (91/134) and R1a1a1b2a2-Z2124 (109/134), which has never been reported. This implied that Kyrgyz ethnic group might have gone through bottleneck effects twice, with these two main lineages left. Mismatch analysis indicated that the biggest mismatch number in haplogroup C2a1a3a1d∼-F10091 was 10, while that of haplogroup R1a1a1b2a2-Z2124 was 20. This huge difference reflected the different substructure in two lineages, suggesting that haplogroup C2a1a3a1d∼-F10091 might have the least admixture compared to the other two lineages. After admixture modelling with other datasets, the conclusion could be drawn that Kyrgyz ethnic group had great genetic affinity with Punjabi from Lahore, Pakistan, which supported that Kyrgyz ethnic group in China was close to central Asian. 相似文献
18.
A simple, rapid and sensitive CE-fluorescence (FL) detection method for the analysis of alendronate (ALEN), a bisphosphonate drug, has been developed. Using a buffer solution of 20 mM sodium phosphate (pH 10.0) and a voltage of 24 kV, separation of ALEN in a 55-cm length (35-cm effective length) capillary was achieved in 5 min. FL detection of ALEN was performed via pre-column derivatization with 2,3-naphthalene dicarbox-yaldehyde (NDA). Linear correlation (r=0.9981, n=6) between FL intensity and analyte concentration was obtained in the range of 7-200 ng/mL ALEN. The developed CE-FL method was applied to the analysis of ALEN in human urine and plasma samples. In order to eliminate the interfering matrix components, SPE using magnetic Fe(3) O(4) @Al(2) O(3) nanoparticles as solid sorbents was employed to clean the biological fluids before CE-FL analysis. The linear ranges of ALEN in urine and plasma were 5-100 ng/mL (r = 0.9982, n = 7) and 5-70 ng/mL (r = 0.9954, n = 7), respectively. The LOD and LOQ in both urine and plasma samples were 1.5 and 5 ng/mL ALEN, respectively. Total analysis time including sample pre-treatment and CE separation was less than 1.5 h. 相似文献
19.
2,6-Di-tert-butyl-p-cresol (DBPC), dibenzyl disulfide (DBDS), and 1,2,3-benzotriazole (BTA) are additives that may be found concomitantly in the oil matrix of power transformer. DBPC and DBDS act as antioxidants while, BTA is a corrosion inhibitor that protects copper conductors inside the transformer unit from corrosion. A powerful analytical method is, therefore, required to determine these additives at trace levels in the transformer oil. This work describes a unique single liquid-liquid extraction pretreatment step prior to the determination of the components by gas chromatography (GC) and high-performance liquid chromatography (HPLC) techniques. The optimum volume ratio used in the pretreatment step was determined as 5:2:5 for mineral oil/n-hexane/acetonitrile, respectively. Relatively, the method is simple and quick with a minimal use of solvents. Analytical results indicate that the method is relatively sensitive, accurate, and precise for each of the three components in fresh and used mineral oil. The calibration curves for the three components demonstrate a significant increase in sensitivities. Detection limits found were, 100 mg L(-1) (0.01% w/v), 0.80 mg L(-1) , and 2.04 mg L(-1) for DBPC, DBDS, and BTA, respectively. The Student's t values determined at 95% confidence level indicate that there is no significant difference between the experimental means obtained by this method and the standard method for each component. 相似文献