痛苦与困惑的呐喊——浅谈《一叶》思想内容与艺术表现的特点

作品在思想内容上 ,着重两个方面的分析 :一方面揭露和控诉了封建主义的“吃人”罪恶 ,体现出了“五四”反封建的时代精神 ;另一方面也表现出了作者在探索“人生究竟是什么”时的困惑和痛苦。在艺术表现中强调了这部作品在景物描写上的多样性、生动性、简洁性 。

一叶情

又是落叶的季节了。还有什么季节，比这个时候更适合叙说叶子的故事？红尘十里，不知几世几劫。一片片叶子的生生灭灭，正如人之一生扰攘来去的不断，还有起起落落的无常。

一叶随风忽报秋

当清凉的秋风裹挟着沁人的秋雨，原本翩然飞舞的秋叶铿然落地，我知道这个美丽的季节如约而至了……虽然向往江南秋色的脉脉含情，“明月如霜，好风如水，清景无限”和“落霞与孤鹜齐飞，秋水共长天一色”的美景让我心中也泛起涟漪，如痴如醉。但我更欣赏北方之秋的那种豪迈深沉萧索，那种“千林落叶随风走，万里长江贴地流”的气魄!南方的秋天只能是浅尝，而北方的秋则让人深醉。

一叶白菜卷春来

淡恋爱时，第一次去拜见准岳父，老人家为我张罗了一桌好酒菜，让我感兴趣的是白菜卷。白菜卷，简单易做，说白了，就是用白菜叶卷上肉馅，然后上锅蒸熟，出锅即食.

Different Understory Cultivation Techniques of Paris polyphylla Smith

This study was conducted for the purposes of reducing consumption of wild resources of Paris polyphylla Smith, satisfying the market demand, saving the production cost, improving utilization rate of forest land, increasing income of foresters and protecting ecological environment. Three types of fores{ land, i.e., the evergreen forest land （China fir forest）, deciduous forest land （walnut forest） and shrub land （honey suckle forest.） were selected, and seeds and cut rhizomes of Paris polyphylla Smith produced in Bamian Mountain, Hunan, were used in the study on understory seedling raising and cultivation techniques. The results showed that： when using different propagation materials, seed propagation could be adopted to reduce the consumption of wild resources and provide a large number of seedlings, and was beneficial to large-scale planting; and when conducing seedling and plantlet raising followed by transplanting and direct seeding and planting using different propagation materials in large-scale understory cultivation, direct seeding/ planting was appropriate for saving save production cost with the advantage of early production. Among the 3 different types of forest land, the best choice was broad- leaved forest land, which could achieve better economic benefit because of con- forming with the ecological habit and growth and development law of Paris poly- phylla Smith.

Regulation of Nitric Oxide on the Aging Process of Wheat Leaves

When the first fully expanded leaf of wheat ( Triticum aestivum L.) seedlings with two leaves were treated with different concentrations (0.05, 0.10, 0.20 and 0.50 mmol/L) of nitric oxide donor, sodium nitroprusside (SNP), the contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA) were reduced by the lower concentrations (0.05, 0.10 and 0.20 mmol/L), but enhanced by the higher concentration of SNP (0.50 mmol/L). The protective effect of 0.10 mmol/L SNP was the most obvious. Furthermore, the treatment with 0.10 mmol/L SNP on the above seedlings until the fourth leaves were fully expanded attenuated the accumulation of H2O2, superoxide anion radical (O-2(-)) and MDA, also counteracted the degradation of chlorophyll and soluble proteins, especally Rubisco, both leading to the effective delay of aging process in wheat leaves. The effects of different SNP concentrations (0.05, 0.10, 0.20, 0.50, 1.00 and 5.00 mmol/L) also displayed a dual role in an aging experiment of chloroplasts in vitro, one of which, 0.2 mmol/L SNP treatment, protected the membrane structure and attenuated the degradation of Rubisco effectively. Based on the present results, it was inferred that lower concentrations of nitric oxide (NO) might play a role in delaying aging process in wheat leaves, i.e., might attribute to decrease the level of reactive oxygen species (ROS) and the alleviation of further oxidative damage caused by ROS.

Effect of Nitrogen, Phosphorus and Potassium on the Content and Yield of DNJ of Mulberry Leaves in Spring

[Objective] This study aimed to scientifically improve the 1-deoxynojimycin （DNJ） yield of mulberry leaves in spring. [Method] ＂3414＂ experimental design was adopted to investigate the effects of different fertilizer application rates of nitrogen, phosphorus and potassium on the DNJ content in mulberry leaves. The regression relationship was further simulated with DNJ yield as the objective function and fertil- izer application rates of nitrogen, phosphorus and potassium as the regulatory factors. [Result] The results showed that nitrogen, phosphorus and potassium all have great effects on the DNJ content in mulberry leaves at different parts of mulberry tree （Morus alba）; the DNJ content in mulberry leaves increases with the increasing single-factor fertilizer application rate and reaches the maximum under N2P2K2 level; different fertilizer application rates and combinations of nitrogen, phosphorus and potassium can significantly affect the DNJ content in mulberry leaves; according to the simulated fertilizer effect function, the optimal economic yield of total DNJ in mul- berry leaves was 23.23 kg/hm^2, the recommended fertilization indicators were 286.11 kg/hm^2 N, 95.22 kg/hm^2 P2O5 and 159.62 kg/hm^2 K20. [Conclusion] After confirmation in productive practice, this optimal fertilization program can provide reference for the construction of mulberry plantation with high yield and high quality of DNJ.

Study on the Mechanism of Innovative Montmorillonite for Diarrhea Treatment

[Objective] This study aimed to investigate the mechanism of innovative montmorillonite for diarrhea treatment. [Method] Thirty healthy weanling piglets （Duroc x Landrace x Yorkshire） were randomly divided into five groups and fed with basal diet, basal diet ＋ 1 g/kg innovative montmorillonite, basal diet ＋ 3 g/kg innovative montmorillonite, basal diet ＋ 5 g/kg innovative montmorillonite and basal diet ＋ 3 g/kg Bacillus subtilis microecologic agent, respectively. After four weeks, blood samples were collected via precaval vein, to detect the content of TFF3, NO and SOD in serum by ELISA kits. [Result] Compared with blank control group, the content of TFF3, NO and SOD in high-dose innovative montmorillonite group was extremely significantly increased, extremely significantly reduced and significantly in- creased, respectively; the content of TFF3 and NO in middle-dose innovative mont- morillonite group was significantly increased and significantly reduced, respectively. [Conclusion] Innovative montmorillonite may exert beneficial therapeutic actions on diarrhea by increasing TFF3 and SOD levels and decreasing NO level.

Dissociation Dynamics of Nitrous Oxide from Jet-cooling Absorption Spectrum in 142.5-147.5 nm

The absorption spectrum of the C1Ⅱ state of N2O molecule in the wavelength range of 142.5-147.5 nm has been measured under the jet-cooled condition, and the clear spectral features are displayed. A vibrational progression is observed with a frequency interval of about 500 cm-1. With the aid of potential energy surfaces （PES） of the low-lying electronic states of N2O, the vibrational progression is assigned as the bending mode of the repulsive C1Ⅱ state. From the Fourier transformation analysis, the recurrence period of the periodic orbit near the transition state region is derived to be 65 fs. Through the least-square Lorentzian fitting, the lifetimes of the resonance levels are estimated from their profile widths to be about 20 fs, which is shorter than the recurrence period. Therefore, a new explanation is suggested for the observed diffuse spectral structure, based on the behavior of dissociating N20 on PES of the C1Ⅱ state in the present excitation energy range.

Combining Principal Component Regression and Artificial Neural Network to Predict Chlorophyll-a Concentration of Yuqiao Reservoir’s Outflow

In order to investigate the eutrophication degree of Yuqiao Reservoir, a hybrid method, combining principal component regression (PCR) and artificial neural network (ANN), was adopted to predict chlorophyll-a concentration of Yuqiao Reservoir’s outflow. The data were obtained from two sampling sites, site 1 in the reservoir, and site 2 near the dam. Seven water variables, namely chlorophyll-a concentration of site 2 at time t and that of both sites 10 days before t, total phosphorus(TP), total nitrogen(TN),...

Effect of Spraying Nutritional Solution ＂PRO.SOL＂ and Chelated Iron on Growth and Flowering of Gazania Plant Gazania splenden L,

The aim of this research was to study the effect of spraying nutritional solution ＂PRO.SOL＂ and chelated iron on vegetative and floral growth characteristics on Gazania plant. Randomized Complete Block Design （R.C.B.D） was adopted utilizing two applications in three replicates. Three concentration levels of nutritional solution PRO.SOL （10.00, 5.00 and 0.00 mg/L） and four concentration levels of chelated iron （90.00, 60.00, 30.00 and 0.00 mg/L） were applied in this experiment. The interaction between the two factors was also measured. The mean values were compared using L.S.D test at probability level 0.05. Spraying PRO.SOL at concentration 10.00 mg/L or chelated iron concentration level 90.00 mg/L improved growth parameters. There was significant increase in： number of total leaves per plant, shoot dry weight, leaves total chlorophyll content, number of off-shoots, number and length of primary roots, length of the peduncle, number of flowers, number of petals and flower dry weight. Meanwhile leaf carbohydrate contents, phosphorus percentage and leaf iron content were increased significantly compared with the （unsprayed plants）. The interaction treatment, spraying nutritional solution PRO.SOL at concentration level 10.00 mg/L with 90 mg Lt chelated iron had a significant increase in all studied growth parameters, i.e., the number of flowers and petals gave 8.33 flowers and 18.67 petals compared with the control treatment which gave 3.33 flowers and 13.00 petals. Meanwhile leaf carbohydrate contents, phosphorus percentage and leaf iron content increased significantly in comparison with the unsprayed plants which gave the least values.

A data-driven early micro-leakage detection and localization approach of hydraulic systems

Leakage is one of the most important reasons for failure of hydraulic systems.The accurate positioning of leakage is of great significance to ensure the safe and reliable operation of hydraulic systems.For early stage of leakage,the pressure of the hydraulic circuit does not change obviously and therefore cannot be monitored by pressure sensors.Meanwhile,the pressure of the hydraulic circuit changes frequently due to the influence of load and state of the switch,which further reduces the accuracy of leakage localization.In the work,a novel Bayesian networks(BNs)-based data-driven early leakage localization approach for multi-valve systems is proposed.Wavelet transform is used for signal noise reduction and BNs-based leak localization model is used to identify the location of leakage.A normalization model is developed to improve the robustness of the leakage localization model.A hydraulic system with eight valves is used to demonstrate the application of the proposed early micro-leakage detection and localization approach.

Influence of Planting Date on the Growth and Yield of Different Maturity Group of Soybeans in the Southeastern Coastal Plains of USA

Planting date is a critical component of soybean [Glycine max （L.） Merr.] production, under dry land conditions in the Southeastern Coastal Plain. The objectives of this study were to 1. Evaluate the effect of planting date on plant leaf area index （LAI） and normalized difference vegetation index （NDVI） at 60 and 90 days after planting （DAP）, plant height and grain yield, and 2. Determine the optimum planting period by integrating the responses from vegetation growth to yield for soybean maturity group （MG） IV-VIII under dry land conditions in the Southeastern Coastal Plain. Planting dates were scheduled about 14-days intervals from late April to mid-July （2008） or late July （2009）. Greatest grain yield for MG IV was obtained from planting in around mid-May in both years. The yield was greater for MG V planted in May and greater for MG VI-VIII planted in late April and May, but started to decline for planting in early June. Plant LAI and NDVI at 60 DAP were affected by both planting date and precipitation, but were poorly correlated with grain yield. However, plant LAI and NDVI were well correlated with yield and were greater for May planting dates at 90 DAP. These indiccs declined for soybean planted after May. Mature plant height decreased more rapidly with delayed planting. These results indicate that plant growth and yield decreased after May planting. Optimum planting period for all MGs was early to mid-May.

Vegetation Dynamics and Its Relationship with Climatic Factors in the Changbai Mountain Natural Reserve

This study examined the temporal variation of the Normalized Difference Vegetation Index （NDVI） and its relationship with climatic factors in the Changbai Mountain Natural Reserve （CMNR） during 2000 - 2009. The results showed as follows. The average NDVI values increased at a rate of 0.0024 year-1. The increase rate differed with vegetation types, such as 0.0034 year-1 for forest and 0.0017 year-1 for tundra. Trend analyses revealed a consistent NDVI increase at the start and end of the growing season but little variation or decrease observed in July during the study period. The NDVI in CMNR showed a stronger correlation with temperature than with precipitation, especially in spring and autumn. A stronger correlation was observed between NDVI and temperature in the tundra zone （2,000-2,600m） than in the coniferous forest （1,100-1,700m） and Korean pine-broadleaved mixed forest （7oo-1,1oom） zones. The results indicate that vegetation at higher elevations is more sensitive to temperature change. NDVI variation had a strong correlation with temperature change （r=0.7311, p〈0.01） but less significant correlation with precipitation change. The result indicates that temperature can serve as a main indicator of vegetation sensitivity in the CMNR.

Coordinated Urban and Rural Development in Yiling

YILING,the largest district in Yichang City,Hubei Province,is noted for its non-metallic mines,tea planting,citrus fruit cultivation,and folk art.In recent years,Yiling＇s focus has been on urban-rural integration.Human Development The strategies of Yiling District include inheriting traditional culture and ensuring sustained development.

一叶之心

那是一个冷清的星期日，路上的行人寥寥无几。 上完奥数课后，我和妈妈一起坐车回家，快到车站时，妈妈突然问：“听你同学说，其中试卷已经发下来了，你考得如何？”

一叶孤舟的追求

一个宁静的夜晚,大海上有一叶孤舟,正迎着晶莹圆润的月亮漂流着……

一叶茶的人生

在寂寥的下午．听着最爱的音乐．忽然记起家中还有一盘上好的绿茶．于是，为自己煮起了一个人的下午茶。

Chemical synthesis and biological activities of Securinega alkaloids

The Securinega alkaloids are a group of compounds isolated from the plants of Securinega,Phyllanthus and Flueggea genera belonging to the Euphorbiaceae family.Most of these compounds exhibit a wide range of biological activities,such as GAB A receptor antagonist,antimalarial and antibacterial activity.Due to the special structural features of Securinega alkaloids, the synthesis strategies for their different structural skeletons are challenging for organic and medicinal chemists.In the review, we will provide an overview of the total synthesis of several Securinega alkaloids and their biological activities.