Sampling studies in North Dakota conducted from 1994 to 2003 showed that variable-rate N application could be practically directed with zone soil sampling. Results from variable-rate N studies using zone soil sampling...Sampling studies in North Dakota conducted from 1994 to 2003 showed that variable-rate N application could be practically directed with zone soil sampling. Results from variable-rate N studies using zone soil sampling were often less than rewarding due in part to the use of a whole-field predicted yield-based formula for developing the N recommendation in each zone. Nitrogen rate studies on spring wheat and durum were established in 2005 through 2009 with the objective to reexamine N recommendations and construct a new system if necessary. The results of the study and archived wheat N response data showed that the state should be divided into three separate N response regions. Within each region historic yields from low to high productivity were defined. The gross N rate was determined using the return-to-N concept developed in the US corn-belt states but with additional consideration for wheat protein value The gross N rate is then modified by credits for previous crop, soil test N from zone soil sampling, tillage systems, excessive straw from the previous year, relative susceptibility to nitrate leaching or denitrification. Finally, the user is encouraged to use common sense and consider whether particular fields have characteristics that require more or less N fertilizer than suggested by the recommendation formulas.展开更多
The theory of evolution was advanced by Darwin in 1859, prior to Mendel’s experiments demonstrating the particulate nature of inheritance. The modern synthesis was formulated in the early 1940s, well before the conce...The theory of evolution was advanced by Darwin in 1859, prior to Mendel’s experiments demonstrating the particulate nature of inheritance. The modern synthesis was formulated in the early 1940s, well before the concept of coded information was understood. This paper outlines four mathematical challenges to the modern synthesis, which are based on current understanding of the proposed mechanisms of evolutionary change within the constraints of experimental molecular biology.展开更多
Spectroscopic studies have revealed that the amount of polyureas formed and the kinetics of their formation in soy based polyurethane systems are considerably different from traditional systems employing ethylene oxid...Spectroscopic studies have revealed that the amount of polyureas formed and the kinetics of their formation in soy based polyurethane systems are considerably different from traditional systems employing ethylene oxide-propylene oxide (EO-PO) based polyols.The aggregation of polyureas was characterized by the hydrogen bonds formed utilizing FTIR spectroscopy.This study offered the opportunity to assign the previously undefined infrared features.The structural transformation is reflected in the segmental rel...展开更多
The purpose of this study was to investigate whether exposing middle school students to content above their ability level produced significant differences in students’confidence in their Chinese as a foreign language...The purpose of this study was to investigate whether exposing middle school students to content above their ability level produced significant differences in students’confidence in their Chinese as a foreign language competence in each of the following four areas:reading,listening,speaking,and learning vocabulary.Participants(N=30)were sixth and seventh graders.Results of paired t-test analyses indicated that there was no significant difference in student confidence in Chinese reading competence,t(30)=0.78,p=0.22;in Chinese speaking competence,t(30)=-0.50,p=0.31;or to learn Chinese vocabulary,t(30)=-0.80,p=0.21.However,there was a significant difference in student confidence in ability to learn Chinese listening,t(30)=-1.78,p<0.05.It is suggested that exposing students to content well above their ability level can increase their confidence in ability to learn Chinese listening.展开更多
In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including trans...In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including transformation temperature, pH, and concentration were optimized by the single-factor method as 90 C, pH 1, and 0.01 mmol/L [Na3Au（SO3）2], respectively. The resultant colloidal transmission electron microscopy images （TEM） and UV-vis absorption spectrophotometer spectra were acquired to check their properties, and the results show this kind of colloidal gold is controlled to 6 nm in sizes and has good stability in solution.展开更多
文摘Sampling studies in North Dakota conducted from 1994 to 2003 showed that variable-rate N application could be practically directed with zone soil sampling. Results from variable-rate N studies using zone soil sampling were often less than rewarding due in part to the use of a whole-field predicted yield-based formula for developing the N recommendation in each zone. Nitrogen rate studies on spring wheat and durum were established in 2005 through 2009 with the objective to reexamine N recommendations and construct a new system if necessary. The results of the study and archived wheat N response data showed that the state should be divided into three separate N response regions. Within each region historic yields from low to high productivity were defined. The gross N rate was determined using the return-to-N concept developed in the US corn-belt states but with additional consideration for wheat protein value The gross N rate is then modified by credits for previous crop, soil test N from zone soil sampling, tillage systems, excessive straw from the previous year, relative susceptibility to nitrate leaching or denitrification. Finally, the user is encouraged to use common sense and consider whether particular fields have characteristics that require more or less N fertilizer than suggested by the recommendation formulas.
文摘The theory of evolution was advanced by Darwin in 1859, prior to Mendel’s experiments demonstrating the particulate nature of inheritance. The modern synthesis was formulated in the early 1940s, well before the concept of coded information was understood. This paper outlines four mathematical challenges to the modern synthesis, which are based on current understanding of the proposed mechanisms of evolutionary change within the constraints of experimental molecular biology.
文摘Spectroscopic studies have revealed that the amount of polyureas formed and the kinetics of their formation in soy based polyurethane systems are considerably different from traditional systems employing ethylene oxide-propylene oxide (EO-PO) based polyols.The aggregation of polyureas was characterized by the hydrogen bonds formed utilizing FTIR spectroscopy.This study offered the opportunity to assign the previously undefined infrared features.The structural transformation is reflected in the segmental rel...
文摘The purpose of this study was to investigate whether exposing middle school students to content above their ability level produced significant differences in students’confidence in their Chinese as a foreign language competence in each of the following four areas:reading,listening,speaking,and learning vocabulary.Participants(N=30)were sixth and seventh graders.Results of paired t-test analyses indicated that there was no significant difference in student confidence in Chinese reading competence,t(30)=0.78,p=0.22;in Chinese speaking competence,t(30)=-0.50,p=0.31;or to learn Chinese vocabulary,t(30)=-0.80,p=0.21.However,there was a significant difference in student confidence in ability to learn Chinese listening,t(30)=-1.78,p<0.05.It is suggested that exposing students to content well above their ability level can increase their confidence in ability to learn Chinese listening.
基金financially supported by the National Natural Science Foundation of China(No.20976201)the Graduate's Scientific Research Foundation of Central South University of Forestry and Technology(No.CX2012B04)
文摘In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including transformation temperature, pH, and concentration were optimized by the single-factor method as 90 C, pH 1, and 0.01 mmol/L [Na3Au（SO3）2], respectively. The resultant colloidal transmission electron microscopy images （TEM） and UV-vis absorption spectrophotometer spectra were acquired to check their properties, and the results show this kind of colloidal gold is controlled to 6 nm in sizes and has good stability in solution.
