Literature review is an important component in any scientific research. In ecological and agricultural sciences, many studies have been conducted over years. With accumulation of scientific studies and published paper...Literature review is an important component in any scientific research. In ecological and agricultural sciences, many studies have been conducted over years. With accumulation of scientific studies and published papers, it is critical to summarize and evaluate these previous research findings. Different literature review methods have been applied, including traditional qualitative literature review, quantitative meta-analysis, and more recently, mega-analysis, or meta-meta-analysis. Here we briefly describe these different approaches and draw attention to the recent development of data synthesis. Several case studies were used to illustrate the application of these methods in the ecological and agricultural sciences.展开更多
O-Aryl O-ethyl N-isopropyl phosphoramidothioates (Ⅰ) have herbicidal activity. In order to study the relationship between structures and activities of these compounds, more than thirty compounds (Ⅰ) have been prepar...O-Aryl O-ethyl N-isopropyl phosphoramidothioates (Ⅰ) have herbicidal activity. In order to study the relationship between structures and activities of these compounds, more than thirty compounds (Ⅰ) have been prepared by the reaction of O-aryl O-ethyl phosphorochloridothioates with isopropylamine in the presence of 40% NaOH at 0℃. The intermediates, phosphorochloridothioates, were prepared separately from a large excess of O-ethyl Phosphorodichloridothioate and various substituted phenols in the presence of 40% NaOH and a catalyrical amount of Et_3N at 0—5℃. As a result, higher purity and good yields were obtained.It was found that the activity of these compounds was highly dependent upon the substituents attached to the benzene ring with respect to the characteristic parameters π, E_s, σ and F by using Hansch's equation.It was indicated that hydrophobic (π), steric (E_s), and electronic (σ and F) effects of the substituents on the ring in those molecules seem to be of considerable importance in determining their biological activity.By replacing π with △R_m and a and F with △δ_p, respectively, in regression analysis a better correlation was obtained. Both △R_m and △δ_p were experimental data. The former was calculated from R_f measured with reversed-phase thin-layer chromatography and the latter was obtained from the difference between the chemical shifts of the ^(31)P NMR of compounds(Ⅰ) and that of the parent compound.展开更多
文摘Literature review is an important component in any scientific research. In ecological and agricultural sciences, many studies have been conducted over years. With accumulation of scientific studies and published papers, it is critical to summarize and evaluate these previous research findings. Different literature review methods have been applied, including traditional qualitative literature review, quantitative meta-analysis, and more recently, mega-analysis, or meta-meta-analysis. Here we briefly describe these different approaches and draw attention to the recent development of data synthesis. Several case studies were used to illustrate the application of these methods in the ecological and agricultural sciences.
文摘O-Aryl O-ethyl N-isopropyl phosphoramidothioates (Ⅰ) have herbicidal activity. In order to study the relationship between structures and activities of these compounds, more than thirty compounds (Ⅰ) have been prepared by the reaction of O-aryl O-ethyl phosphorochloridothioates with isopropylamine in the presence of 40% NaOH at 0℃. The intermediates, phosphorochloridothioates, were prepared separately from a large excess of O-ethyl Phosphorodichloridothioate and various substituted phenols in the presence of 40% NaOH and a catalyrical amount of Et_3N at 0—5℃. As a result, higher purity and good yields were obtained.It was found that the activity of these compounds was highly dependent upon the substituents attached to the benzene ring with respect to the characteristic parameters π, E_s, σ and F by using Hansch's equation.It was indicated that hydrophobic (π), steric (E_s), and electronic (σ and F) effects of the substituents on the ring in those molecules seem to be of considerable importance in determining their biological activity.By replacing π with △R_m and a and F with △δ_p, respectively, in regression analysis a better correlation was obtained. Both △R_m and △δ_p were experimental data. The former was calculated from R_f measured with reversed-phase thin-layer chromatography and the latter was obtained from the difference between the chemical shifts of the ^(31)P NMR of compounds(Ⅰ) and that of the parent compound.
