基于传统的词典释义往往无法对某些语言使用的实例进行充分的描述,本文运用生成词库理论的相关假设,探讨英语动词pour的动态语义并对语言使用的实例进行阐释。本文考察了英语动词pour的4种句法结构以及句法组合成分的语义匹配。研究发现...基于传统的词典释义往往无法对某些语言使用的实例进行充分的描述,本文运用生成词库理论的相关假设,探讨英语动词pour的动态语义并对语言使用的实例进行阐释。本文考察了英语动词pour的4种句法结构以及句法组合成分的语义匹配。研究发现,通过论元选择生成机制,动词和介词选择与之匹配的论元;组合名词的物性结构促成动词的逻辑多义,甚至影响动词的句法表现:如动词pour的"创造"义、"物质发散"义、"发射"义等的产生,以及对[N1 V N2]结构和中动结构的影响;动词与其组合论元的语义融合性需考虑组合成分优先作用次序。展开更多
Acetylspiramycin（ASPM）,a 16-membered basic macrolide antibiotic,is the acetylated derivative of spiramycin.In addition to the four main components,more than seventy minor components could be present in ASPM.Thus,it ...Acetylspiramycin（ASPM）,a 16-membered basic macrolide antibiotic,is the acetylated derivative of spiramycin.In addition to the four main components,more than seventy minor components could be present in ASPM.Thus,it is a challenge to obtain a baseline separation of ASPM components.Meanwhile,in some cases it was found that the results obtained by different brands of C_（18） columns were significantly different,indicating the necessity of a rational column selection for the separation of ASPM components.In this paper,we attempted to facilitate column selection for the analysis of ASPM using the database of the column characterization system established by Leuven University.With the CAPCELL PAK MG C_（18）（250 mm×4.6 mm,5μm） as the reference column,three groups of columns（F2 group：similar selectivity;2F6：intermediate ranked group;F6 group： different selectivity,compared to the reference column） were selected,and their performances in the separation of ASPM components were evaluated under the chromatographic conditions described in Chinese Pharmacopoeia monograph.A good relationship was demonstrated between the ranking of columns and their selectivity in the separation of ASPM components,indicating the column classification system established by Leuven University was a helpful tool in the selection of suitable columns for the analysis of ASPM,a complex mixture of basic compounds.展开更多
A full account of the novel and flexible approach to hydroxylated 8-azabicyclo[3,2,1]octan-3-ones and 9-azabicyclo[3,3,1] nonan-3-ones is presented. Using keto-lactams as the starting materials, this two-step method c...A full account of the novel and flexible approach to hydroxylated 8-azabicyclo[3,2,1]octan-3-ones and 9-azabicyclo[3,3,1] nonan-3-ones is presented. Using keto-lactams as the starting materials, this two-step method consists of silyl enol ether for mation with TBDMSOTf, lactam activation with Tf20/DTBMP, and halide-promoted cyclization. Radical dechlorination of the resulting 1-halotropan-3-ones led to the corresponding hydroxylated tropan-3-ones, which can be hydrogenated to yield 3ct,613-dihydroxytropanes. Starting from optically active keto-lactams, the method has been applied to the enantioselective syntheses of （＋）-（1S,3S,5R,6S）-pervilleine C （6）, （＋）-（1S,3R,5S,6R）-valeroidine （3）, （＋）-（1S,3S,5R,6S）-dibenzoyloxytropane （8） and （＋）-（1S,3S,5R,6S）-merredissine （9）.展开更多
Sensory drive predicts coevolution of mate choice signals with the sensory systems detecting those sig nals. Guppies are a classic model for sensory drive as mate preferences based on coloration differ across individu...Sensory drive predicts coevolution of mate choice signals with the sensory systems detecting those sig nals. Guppies are a classic model for sensory drive as mate preferences based on coloration differ across individuals and populations. A large body of work has identified variation in color vision, yet we lack a dir ect tie between how such variation in color vision influences variation in color preference. Here we bring together studies that have investigated guppy vision over the past 40years to： （1） highlight our current understanding of where variation occurs in the guppy color vision pathway and （2） suggest future ave nues of research into sources of visual system variation that could influence guppy color preference. This will allow researchers to design careful studies that couple measures of color preference with measures of visual system variation from the same individual or population. Such studies will finally provide im portant answers as to what sets the direction and speed of mate preference evolution via sensory drive.展开更多
When hybridization results in reduced fitness, natural selection is expected to favor the evolution of traits that minimize the likelihood of hybridizing in the first place. This process, termed reinforcement （or, mo...When hybridization results in reduced fitness, natural selection is expected to favor the evolution of traits that minimize the likelihood of hybridizing in the first place. This process, termed reinforcement （or, more generally, reproductive character displacement）, thereby contributes to the evolution of enhanced reproductive isolation between hybridizing groups. By enhancing reproductive isolation in this way, reinforcement plays an important role in the final stages of speciation. However, reinforcement can also contribute to the early stages of speciation. Specifically, because selection to avoid hybridization occurs only in sympatric populations, the unfolding of reinforcement can lead to the evolution of traits in sympatric populations that reduce reproduction between conspecifics in sympatry versus those in allopatry. Thus, reinforcement between species can lead to reproductive isolation--and possibly speciation-between populations in sympatry versus those in allopatry or among different sympatric populations. Here, I describe how this process can occur, the conditions under which it is most likely to occur, and the empirical data needed to evaluate the hypothesis that reinforcement can initiate speciation.展开更多
Speciation research during the last several decades has confirmed that natural selection frequently drives the genera- tion of new species. But how does this process generally unfold in nature？ We argue that answerin...Speciation research during the last several decades has confirmed that natural selection frequently drives the genera- tion of new species. But how does this process generally unfold in nature？ We argue that answering this question requires a clearer conceptual framework for understanding selection＇s role in speciation. We present a unified framework of speciation, pro- viding mechanistic descriptions of fundamentally distinct routes to speciation, and how these may interact during lineage splitting Two major categories are recognized： reproductive isolation resulting from （1） responses to selection, ＂speciation by selection,＂ or （2） non-selective processes, ＂speciation without selection.＂ Speciation by selection can occur via three mechanisms： （1） similar selection, （2） divergent selection, and （3） reinforcement selection. Understanding ecology＇s role in speciation requires uncovering how these three mechanisms contribute to reproductive isolation, and their relative importance compared to non-selective proce- sses, because all three mechanisms can occur side-by-side during speciation. To accomplish this, we highlight examination of groups of organisms inhabiting replicated environmental gradients. This scenario is common in nature, and a large literature illus- trates that both parallel and non-parallel responses to similar environments are widespread, and each can result in speciation. This recognition reveals four general pathways of speciation by similar or divergent selection--parallel and nonparallel responses to similar and divergent selection. Altogether, we present a more precise framework for speciation research, draw attention to some under-recognized features of speciation, emphasize the multidimensionality of speciation, reveal limitations of some previous tests and descriptions of speciation mechanisms, and point to a number of directions for future investigation [Current Zoology 59 （1）： 31-52, 2013].展开更多
文摘基于传统的词典释义往往无法对某些语言使用的实例进行充分的描述,本文运用生成词库理论的相关假设,探讨英语动词pour的动态语义并对语言使用的实例进行阐释。本文考察了英语动词pour的4种句法结构以及句法组合成分的语义匹配。研究发现,通过论元选择生成机制,动词和介词选择与之匹配的论元;组合名词的物性结构促成动词的逻辑多义,甚至影响动词的句法表现:如动词pour的"创造"义、"物质发散"义、"发射"义等的产生,以及对[N1 V N2]结构和中动结构的影响;动词与其组合论元的语义融合性需考虑组合成分优先作用次序。
文摘Acetylspiramycin（ASPM）,a 16-membered basic macrolide antibiotic,is the acetylated derivative of spiramycin.In addition to the four main components,more than seventy minor components could be present in ASPM.Thus,it is a challenge to obtain a baseline separation of ASPM components.Meanwhile,in some cases it was found that the results obtained by different brands of C_（18） columns were significantly different,indicating the necessity of a rational column selection for the separation of ASPM components.In this paper,we attempted to facilitate column selection for the analysis of ASPM using the database of the column characterization system established by Leuven University.With the CAPCELL PAK MG C_（18）（250 mm×4.6 mm,5μm） as the reference column,three groups of columns（F2 group：similar selectivity;2F6：intermediate ranked group;F6 group： different selectivity,compared to the reference column） were selected,and their performances in the separation of ASPM components were evaluated under the chromatographic conditions described in Chinese Pharmacopoeia monograph.A good relationship was demonstrated between the ranking of columns and their selectivity in the separation of ASPM components,indicating the column classification system established by Leuven University was a helpful tool in the selection of suitable columns for the analysis of ASPM,a complex mixture of basic compounds.
基金the National Basic Research Program of China(973 Program,2010CB833200)the National Natural Science Foundation of China(21072160,21332007)the Program for Changjiang Scholars and Innovative Research Team at the University of the MOE for financial support
文摘A full account of the novel and flexible approach to hydroxylated 8-azabicyclo[3,2,1]octan-3-ones and 9-azabicyclo[3,3,1] nonan-3-ones is presented. Using keto-lactams as the starting materials, this two-step method consists of silyl enol ether for mation with TBDMSOTf, lactam activation with Tf20/DTBMP, and halide-promoted cyclization. Radical dechlorination of the resulting 1-halotropan-3-ones led to the corresponding hydroxylated tropan-3-ones, which can be hydrogenated to yield 3ct,613-dihydroxytropanes. Starting from optically active keto-lactams, the method has been applied to the enantioselective syntheses of （＋）-（1S,3S,5R,6S）-pervilleine C （6）, （＋）-（1S,3R,5S,6R）-valeroidine （3）, （＋）-（1S,3S,5R,6S）-dibenzoyloxytropane （8） and （＋）-（1S,3S,5R,6S）-merredissine （9）.
文摘Sensory drive predicts coevolution of mate choice signals with the sensory systems detecting those sig nals. Guppies are a classic model for sensory drive as mate preferences based on coloration differ across individuals and populations. A large body of work has identified variation in color vision, yet we lack a dir ect tie between how such variation in color vision influences variation in color preference. Here we bring together studies that have investigated guppy vision over the past 40years to： （1） highlight our current understanding of where variation occurs in the guppy color vision pathway and （2） suggest future ave nues of research into sources of visual system variation that could influence guppy color preference. This will allow researchers to design careful studies that couple measures of color preference with measures of visual system variation from the same individual or population. Such studies will finally provide im portant answers as to what sets the direction and speed of mate preference evolution via sensory drive.
文摘When hybridization results in reduced fitness, natural selection is expected to favor the evolution of traits that minimize the likelihood of hybridizing in the first place. This process, termed reinforcement （or, more generally, reproductive character displacement）, thereby contributes to the evolution of enhanced reproductive isolation between hybridizing groups. By enhancing reproductive isolation in this way, reinforcement plays an important role in the final stages of speciation. However, reinforcement can also contribute to the early stages of speciation. Specifically, because selection to avoid hybridization occurs only in sympatric populations, the unfolding of reinforcement can lead to the evolution of traits in sympatric populations that reduce reproduction between conspecifics in sympatry versus those in allopatry. Thus, reinforcement between species can lead to reproductive isolation--and possibly speciation-between populations in sympatry versus those in allopatry or among different sympatric populations. Here, I describe how this process can occur, the conditions under which it is most likely to occur, and the empirical data needed to evaluate the hypothesis that reinforcement can initiate speciation.
文摘Speciation research during the last several decades has confirmed that natural selection frequently drives the genera- tion of new species. But how does this process generally unfold in nature？ We argue that answering this question requires a clearer conceptual framework for understanding selection＇s role in speciation. We present a unified framework of speciation, pro- viding mechanistic descriptions of fundamentally distinct routes to speciation, and how these may interact during lineage splitting Two major categories are recognized： reproductive isolation resulting from （1） responses to selection, ＂speciation by selection,＂ or （2） non-selective processes, ＂speciation without selection.＂ Speciation by selection can occur via three mechanisms： （1） similar selection, （2） divergent selection, and （3） reinforcement selection. Understanding ecology＇s role in speciation requires uncovering how these three mechanisms contribute to reproductive isolation, and their relative importance compared to non-selective proce- sses, because all three mechanisms can occur side-by-side during speciation. To accomplish this, we highlight examination of groups of organisms inhabiting replicated environmental gradients. This scenario is common in nature, and a large literature illus- trates that both parallel and non-parallel responses to similar environments are widespread, and each can result in speciation. This recognition reveals four general pathways of speciation by similar or divergent selection--parallel and nonparallel responses to similar and divergent selection. Altogether, we present a more precise framework for speciation research, draw attention to some under-recognized features of speciation, emphasize the multidimensionality of speciation, reveal limitations of some previous tests and descriptions of speciation mechanisms, and point to a number of directions for future investigation [Current Zoology 59 （1）： 31-52, 2013].
