Graphene, a well-known two-dimensional(2 D) material, has sparked broad enthusiasm in both scientific and industrial communities in these years, due to its exceptional electrical, thermal, mechanical, and versatile pr...Graphene, a well-known two-dimensional(2 D) material, has sparked broad enthusiasm in both scientific and industrial communities in these years, due to its exceptional electrical, thermal, mechanical, and versatile properties. However, many properties and applications of graphene are layer-number dependent. The preparation of high-quality graphene with controlled layer numbers is full of challenge, since the layer number varies much with the synthesis routes and relevant experimental conditions. Hence, there is an urgent need to improve the layer-number controllability of graphene preparation. Generally, graphene can be prepared by two complementary approaches: "top-down" and "bottom-up". Since they have their own advantages, the recent advances in the layer-number tunable preparation of high-quality graphene are separately studied from the two aspects in this review, especially those dedicated to single parameter. Some effective strategies are discussed in detail, mainly including 1) supercritical-CO2 assisted sonication, electrochemical exfoliation of graphite intercalation compounds, and layer-by-layer thinning with plasma or laser, for "top-down" graphene;2) chemical vapor deposition(CVD) on dual-metal substrate, ion-implantation CVD, layer-by-layer CVD, plasma-enhanced CVD, layered-double-hydroxides template-assisted CVD;and 3) graphite-enclosure assisted epitaxial growth and pulsed-magnetron-sputtering assisted physical vapor deposition for "bottom-up" graphene on various substrates. In addition, the respective advantages of graphene with different layer numbers in properties and applications are also presented. Finally, the contribution concludes with some important perspectives on the remained challenges and future perspectives.展开更多
[Objectives]This study was conducted to construct high-yielding,high-quality,and high-light-efficiency population structures of different types of rice varieties.[Methods]The effects of plant spacing,row spacing and s...[Objectives]This study was conducted to construct high-yielding,high-quality,and high-light-efficiency population structures of different types of rice varieties.[Methods]The effects of plant spacing,row spacing and seedling number allocation on stems and tillers,leaf area and dynamic traits of high-yielding rice populations(more than 9750 kg/hm^(2))and low-yielding populations(less than 9750 kg/hm^(2))were studied by two kinds of representative rice varieties with different tiller ability and panicle sizes in cold regions.[Results]Decreasing the plant and row spacing and increasing the number of planted seedlings per hole advanced the heading date and made the number of stems and tillers in the population increase.The impact on the super rice variety with fewer tillers and heavier panicles was greater than that of conventional variety with more tillers and lighter panicles.The stems and tillers of the high-yielding high-quality populations grew steadily in the early stage of development,until an appropriate number of panicles was reached at the critical leaf age for productive tillers(June 25),and the peak seedlings should appear in the jointing stage(July 9)with a small number(that value of Longjing 21,the super rice variety with fewer tillers and heavier panicles,was about 1.2 times the expected panicle number,and that of the conventional variety with more tillers and lighter panicles,Kongyu 131,was about 1.1 times the expected panicle number).The populations gradually declined since then,until reaching an appropriate number of panicles at the heading stage.The high-yielding high-quality populations had a higher leaf area index at the heading stage.The value of Longjing 21,the super rice variety with fewer tiller and heavier panicles,reached about 6.0,and that of Kongyu 131,the conventional variety with more tillers and lighter panicles,reached about 4.5.The values decreased thereafter.At the maturation stage,the leaf area index of Longjing 21 remained above 2.5,and that of Kongyu 131 remained above 2.0.[Conclusions]This study has an important guiding role and significance for their high-yielding and high-quality supporting cultivation in cold regions.展开更多
目的探讨中医(补肾健脾)预培其损序贯疗法对胚胎反复移植失败(repeated implantation fail-ure,RIF)患者新鲜周期相关指标的影响。方法将既往行体外受精-胚胎移植(in virto fertilization and em-bryo transfer,IVF-ET)或卵母细胞单精...目的探讨中医(补肾健脾)预培其损序贯疗法对胚胎反复移植失败(repeated implantation fail-ure,RIF)患者新鲜周期相关指标的影响。方法将既往行体外受精-胚胎移植(in virto fertilization and em-bryo transfer,IVF-ET)或卵母细胞单精子显微注射(intracytoplasmic sperm injection,ICSI)失败3次及以上的患者,行新鲜取卵/移植周期共60例,分为治疗组(中药结合IVF/ICSI)与对照组(单纯IVF/ICSI),每组30例,比较两组外源性促性腺激素(gonadotropin,Gn)用量、超排卵(controlled ovarian hyperstimulation,COH)时间、移植日子宫内膜厚度、获得卵数、受精数、胚胎数、优质胚胎数、妊娠率及种植率等各项指标的差异。结果治疗组单周期人均获得胚胎(7.5±4.9)个,优质胚胎(5.1±3.8)个,两者较对照组(5.1±3.2,3.2±1.8)均明显升高,差异均有统计学意义(P<0.05)。两组在Gn用量、COH天数、移植日子宫内膜厚度、获得卵数、受精数、妊娠率及种植率方面比较,差异均无统计学意义(P>0.05)。结论中医预培其损序贯疗法结合超排卵有利于胚胎数量和质量的双重提高,有望增加RIF患者的累计妊娠率。展开更多
基金Sponsored by the JSPS Invitational Fellow ship for Research in Japan (Grant No. L18516)the National Natural Science Foundation of China(Grant No. 51273148)
文摘Graphene, a well-known two-dimensional(2 D) material, has sparked broad enthusiasm in both scientific and industrial communities in these years, due to its exceptional electrical, thermal, mechanical, and versatile properties. However, many properties and applications of graphene are layer-number dependent. The preparation of high-quality graphene with controlled layer numbers is full of challenge, since the layer number varies much with the synthesis routes and relevant experimental conditions. Hence, there is an urgent need to improve the layer-number controllability of graphene preparation. Generally, graphene can be prepared by two complementary approaches: "top-down" and "bottom-up". Since they have their own advantages, the recent advances in the layer-number tunable preparation of high-quality graphene are separately studied from the two aspects in this review, especially those dedicated to single parameter. Some effective strategies are discussed in detail, mainly including 1) supercritical-CO2 assisted sonication, electrochemical exfoliation of graphite intercalation compounds, and layer-by-layer thinning with plasma or laser, for "top-down" graphene;2) chemical vapor deposition(CVD) on dual-metal substrate, ion-implantation CVD, layer-by-layer CVD, plasma-enhanced CVD, layered-double-hydroxides template-assisted CVD;and 3) graphite-enclosure assisted epitaxial growth and pulsed-magnetron-sputtering assisted physical vapor deposition for "bottom-up" graphene on various substrates. In addition, the respective advantages of graphene with different layer numbers in properties and applications are also presented. Finally, the contribution concludes with some important perspectives on the remained challenges and future perspectives.
基金Natural Science Foundation of Heilongjiang Province(LH2019C063)"Agricultural Science and Technology Innovation Project"of Heilongjiang Academy of Agriculture Sciences(HNK2019CX12-08)+1 种基金Academy-level Project of Heilongjiang Academy of Agriculture Sciences(2020YYYF021)National Key R&D Project(2017YFD0300505-4).
文摘[Objectives]This study was conducted to construct high-yielding,high-quality,and high-light-efficiency population structures of different types of rice varieties.[Methods]The effects of plant spacing,row spacing and seedling number allocation on stems and tillers,leaf area and dynamic traits of high-yielding rice populations(more than 9750 kg/hm^(2))and low-yielding populations(less than 9750 kg/hm^(2))were studied by two kinds of representative rice varieties with different tiller ability and panicle sizes in cold regions.[Results]Decreasing the plant and row spacing and increasing the number of planted seedlings per hole advanced the heading date and made the number of stems and tillers in the population increase.The impact on the super rice variety with fewer tillers and heavier panicles was greater than that of conventional variety with more tillers and lighter panicles.The stems and tillers of the high-yielding high-quality populations grew steadily in the early stage of development,until an appropriate number of panicles was reached at the critical leaf age for productive tillers(June 25),and the peak seedlings should appear in the jointing stage(July 9)with a small number(that value of Longjing 21,the super rice variety with fewer tillers and heavier panicles,was about 1.2 times the expected panicle number,and that of the conventional variety with more tillers and lighter panicles,Kongyu 131,was about 1.1 times the expected panicle number).The populations gradually declined since then,until reaching an appropriate number of panicles at the heading stage.The high-yielding high-quality populations had a higher leaf area index at the heading stage.The value of Longjing 21,the super rice variety with fewer tiller and heavier panicles,reached about 6.0,and that of Kongyu 131,the conventional variety with more tillers and lighter panicles,reached about 4.5.The values decreased thereafter.At the maturation stage,the leaf area index of Longjing 21 remained above 2.5,and that of Kongyu 131 remained above 2.0.[Conclusions]This study has an important guiding role and significance for their high-yielding and high-quality supporting cultivation in cold regions.
