不同释放期控释肥和水氮用量对冬小麦产量的综合影响

为揭示不同释放期控释肥及其水肥用量对冬小麦产量的影响，优化冬小麦水氮管理措施，采用裂区设计进行田间试验，以灌水量为主处理，施氮量和控释肥类型分别为副处理和次副处理，其中，灌水量设30、60和90 mm；施氮量设0、75、150和225 kg/hm2的施肥梯度；控释肥类型包括释放期分别为60、120 d的聚氨酯包膜尿素（PCU60，PCU120），以普通尿素作为对照（U）。结果表明：灌水量、施氮量、控释肥类型单一因素均对冬小麦有效穗数、千粒质量、干物质质量、籽粒产量有显著影响。各因素两两之间的交互作用对籽粒产量有显著影响。相较于U处理，增加灌水使PCU60产量平均提高308 kg/hm2，PCU120产量平均下降270 kg/hm2；增施氮肥刚好相反，使PCU60产量平均下降289 kg/hm2，PCU120产量平均提高118 kg/hm2。根据所构建3种肥料的水氮生产函数可知，在U处理取得最高理论产量6 823 kg/hm2时的水氮用量下，2种释放期的控释肥PCU120和PCU60可分别获得14.31%和12.08%的增产效果。利用水氮生产函数和频率分析法得到不同控释肥类型获得较高产量的水氮用量区间，以PCU120产量最高、所需灌水量最低，分别为7 744～7 826 kg/hm2、47.72～52.28 mm；PCU60所需施氮量最低，为145.42～187.91 kg/hm2。综合考虑增产节肥节水效果，推荐PCU120为冬小麦季适宜的控释肥类型，其适宜水氮用量区间分别为47.72～52.28 mm、159.23～199.47 kg/hm2。     

Effect of Jieyuwan on depression-like behaviors and expression of BDNF in hippocampus and prefrontal cortex of WKY rats

AIM:To investigate the mechanism of depression and its development, and to study the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus and prefrontal cortex of Wistar-Kyoto (WKY) rats treated with Jieyuwan. METHODS:Adult male WKY rats were used as an animal model of endogenous depression. Wistar rats of the same strain were selected as control group. WKY rats were randomly divided into model group, citalopram group and Jieyuwan group. After intragastric administration for 21 d, the changes of depression-like behaviors were observed by sucrose preference test and forced swimming test. Immunofluorescence and Western blot were used to detect the expression of BDNF in the hippocampus and prefrontal cortex. RESULTS:WKY rats showed significant depression-like behaviors, and the expression of BDNF was significantly decreased in the hippocampus and prefrontal cortex (P<0.01). The reduction of neuronal axons in hippocampus was also observed. After drug treatment, the depression-like behaviors of WKY rats were significantly attenuated, and the expression of BDNF and the number of axons were increased (P<0.01). CONCLUSION:Jieyuwan effectively attenuates the depression-like behaviors of WKY rats, and BDNF is a key factor in its antidepressant effect. Our findings further confirm the involvement of BDNF in the development of depression.     

Shikonin reverses HGF-induced resistance to gefitinib in lung cancer cells HCC827

AIM: To investigate the effect of shikonin on reversing hepatocyte growth factor(HGF)-induced resistance to gefitinib in lung cancer HCC827 cells, and to explore its possible mechanisms.METHODS: The gefitinib-resistant HCC827 cells induced by HGF were treated with shikonin and gefitinibthe alone or in combination. The inhibition rates of cell viability were determined by MTT assay. The invasive ability of HCC827 cells with HGF-induced resistance to gefitinib was determined by Transwell assay. The protein levels of epithelial-mesenchymal transition (EMT) and related signaling pathway in the HCC827 cells were detected by Western blot.RESULTS: The results of MTT assay showed that the cell activity of HCC827 cells was significantly inhibited by shikonin in a dose dependent manner. The IC₅₀ of shikonin in HCC827 cells was 3.06 μmol/L. And the IC₅₀ of gefitinib in HCC827 cells was 0.51 μmol/L. Under the condition of combined treatment with shikonin and gefitinib in the presence of HGF (20 μg/L), the IC₅₀ of gefitinib was 7.36 μmol/L, significantly lower than that treated with gefitinib alone (P<0.01), so did the result of the cell migration (P<0.01). HGF induced EMT, while shikonin reversed this effect. The protein expression level of p-AKT was significantly up-regulated by HGF, while markedly down-regulated treatment with shikonin and gefitinib compared with gefitinib alone (P<0.01).CONCLUSION: Shikonin reverses HGF-induced resistance to gefitinib in lung cancer HCC827 cells, and the mechanism may be likely related to the preventon of EMT and the inhibition of HGF-induced activation of p-AKT signaling pathway.     

白浆土的氮素分布特征

本文以黑龙江省三江平原耕地白浆土为主要研究对象,并以复区内存在的草甸土和暗棕壤作比较,研究了土壤各种理化性质与不同形态氮素之间的相关关系:白浆土中 HA 和 FA 的主要差别,在于前者含有较多的碱性氨基酸,而后者则含有较多的酸性氨基酸;各种不同形状 N素与土壤 pH 值,质地等相关性不显著,而与土壤有机质、全 N 和 C/N 比值等的相关性极为显著。     

Direct and Residual Contributions of Symbiotic Nitrogen Fixation by Legumes to the Yield and Nitrogen Uptake of Maize (Zea mays L.) in the Nigerian Savannah

Field experiments were conducted to determine the direct and residual contributions of legumes to the yield and nitrogen (N) uptake of maize during the wet seasons of 1994 and 1995 at the University Farm, Abubakar Tafawa Balewa University, Bauchi, Nigeria, located in the Northern Guinea savannah of Nigeria. Nodulating soybean, lablab, green gram and black gram contributed to the yield and N uptake of maize either intercropped with the legumes or grown after legumes as a sole crop. Direct transfer of N from the nodulating soybean, lablab, green gram and black gram to the intercropped maize was 24.9–28.1, 23.8–29.2, 19.7–22.1 and 18.4–18.6 kg N ha^–1, respectively. However, the transfer of residual N from these legumes to the succeeding maize crop was 18.4–20.0, 19.5–29.9, 12.0–13.7 and 9.3–10.3 kg N ha^–1, respectively. Four years of continuous lablab cropping resulted in yields and N uptake of the succeeding maize crop grown without fertilizer N that were comparable to the yields and N uptake of the succeeding maize crop supplied with 40–45 kg N ha^–1 and grown after 4 years of continuous sorghum cropping. It may therefore be concluded that nodulating soybean, lablab, green gram and black gram may be either intercropped or grown in rotation with cereals in order to economize the use of fertilizer N for maize production in the Nigerian savannah.     

黄瓜耐弱光性的多元统计分析

 利用遮阳网模拟弱光条件, 调查18份黄瓜自交系苗期生长发育和生理生化指标, 采用多元统计分析方法评价黄瓜品系耐弱光性强弱。结果表明, 参试品系的13个指标在品系间存在显著差异, 利用因子分析将这些指标综合成5个主因子, 累计贡献率达85.62%。对旋转后的因子得分进行聚类分析, 供试品系可分为4类: 耐弱光材料M₂₂、M₄₃、M_a9; 较耐弱光材料M₈、M₁₁、M₃、M₄、M₃₄; 弱光中度敏感材料M₁₂、M₂₁、M₁₄、M₂、M_a1、M₂₈和弱光敏感材料M₁₀、M₄₄、M₃₂、M₃₆。经过弱光处理后耐弱光指数较大、光合速率降低幅度较小的品系耐弱光性强, 应结合耐弱光指数与光合、生长等因子综合进行黄瓜耐弱光性鉴定。     

氮吸附法分析生物质焦孔隙结构

采用氮吸附法对4种生物质焦(稻壳、树叶、玉米秆、棉花秆)的孔隙结构进行测量,结果表明,不同种类焦样的比表面积和孔径分布有明显差别,树叶的比表面积最大,为242.21 m2·g-1,玉米秆的比表面积最小,为0.81 m2·g-1.850℃时,稻壳、树叶、玉米秆焦样的孔径分布曲线在微孔和中孔范围各有一个分布峰,而棉花秆焦样的孔径分布曲线只在中孔范围内出现一个分布峰.热解温度是影响孔隙结构的一个重要因素,在高温条件下,同步热解得到的焦样的比表面积较大,微孔较多.在本研究中,600℃、850℃的稻壳焦样和850℃的树叶焦样具有较大的比表面积,比较适合做吸附剂.     

铜对生长猪肝中IGF—Ⅰ基因mRNA表达的影响

采用生长试验、免疫放射分析和定量PCR方法，观察了生长猪血液中类胰岛素生长因子（IGF—Ⅰ）及其结合蛋白（IGFBP3）数量的变化和IGF—Ⅰ基因在肝中表达量的变化。结果显示，每1kg饲料中添加125-250mg铜，能够上调IGF-Ⅰ基因的表达量，显著提高猪的平均日增重，促进生长猪循环血液中IGF—Ⅰ浓度的增加。试验结果证实，铜是通过促进生长激素一胰岛素样生长因子轴相关因子的合成和分泌来发挥促生长作用的。     

着床与生长因子的关系研究进展

论述了着床的生理机制。同时介绍了EGF、TGF、KGF和PDGF等生长因子对着床的调控作用。     

Boundary-fitted grid in landscape modeling

Landscape modeling requires the delineation of system boundaries and interior features. Quite often, these components are complex and difficult to accurately represent. A rectangular grid is used to represent the study and adjacent non-study areas in most cases. When the non-study area occupies a large portion of the grid, computer memory is wasted, and computational time increases. An elliptical grid generator for non-orthogonal curvilinear coordinates is used to generate a boundary-fitted grid for a landscape model. In a boundary-fitted grid coordinate system, one coordinate axis follows the landscape domain boundary and is non-orthogonal to the second axis. The boundary-fitted grid uses elliptic partial differential equations to distribute grid points inside the landscape domain. Although the boundary-fitted grid follows the domain boundary, the grid pattern and point allocation remain structured. Thus, a landscape model can use a boundary-fitted grid without changing the model’s data structure or the computational scheme. In this study, a boundary-fitted grid and a raster-based grid were applied to the Everglades Landscape Fire Model. Use of the boundary-fitted grid decreased model simulation time by about one fifth and computer storage by 58% relative to the raster-based grid. Also, the linear characteristics of interior geographical features such as rivers and airboat trails were preserved by the boundary-fitted grid, but not by the raster-based grid. This preservation provided a more reasonable base map for simulating ecological processes, such as fire across heterogenous landscapes.