解剖学和形态学
麻醉学
听力与言语-语言病理学
行为科学
心脏和心血管系统
细胞和组织工程学
临床神经病学
危重症监护医学
牙科,口腔外科和医学
皮肤病学
急诊医学
内分泌学和新陈代谢
肠胃学和肝脏学
老人病学和老年医学
卫生保健科学和服务
血液学
免疫学
传染病
综合和补充性医学
医学伦理学
医学信息学
医学实验室技术
医学,全科和内科
医学,法律
医学,研究和试验
神经系统科学
护理
营养学和饮食学
产科医学和妇科医学
肿瘤学
眼科学
整形外科学
耳鼻喉科学
病理学
儿科学
周围血管疾病
药理学和药剂学
生理学
基本医疗保健
精神病学
公共、环境和职业卫生
放射学,核医学和医学成像
康复学
生殖生物学
呼吸系统
风湿病学
运动科学
外科学
毒理学
热带医学
泌尿学和肾脏学
病毒学
老年医学
健康政策和服务
心理学,临床
abstract:PREMISE OF THE STUDY:Climate change models for California predict a warmer, drier future, potentially resulting in shorter growing seasons. If phenotypic differences between closely related species currently distributed across a moisture and temperature gradient represent adaptations to their abiotic environment, then ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500108
更新日期:2016-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Although our awareness of ploidy diversity has expanded with the application of flow cytometry, we still know little about the extent to which cytotypes within mixed-ploidy populations are genetically differentiated across environmental gradients. METHODS:To address this issue, we reared 14 popula...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500146
更新日期:2016-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Geographic patterns of biodiversity have long inspired interest in processes that shape the assembly, diversity, and dynamics of communities at different spatial scales. To study mechanisms of community assembly, ecologists often compare spatial variation in community composition (beta-diversity) a...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500079
更新日期:2016-01-01 00:00:00
abstract::In an age of rapid global change, it is imperative that we continue to improve our understanding of factors that govern genetic differentiation in plants to inform biologically reasonable predictions for the future and enlighten conservation and restoration practices. In this special issue, we have assembled a set of ...
journal_title:American journal of botany
pub_type:
doi:10.3732/ajb.1500515
更新日期:2016-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Herbivory affects pollination success and reproductive output in plants. However, the different stages in the process from pollination to seed maturation have hardly been investigated within the context of herbivory. Herbivory might affect these stages via its effect on geitonogamous pollination an...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500291
更新日期:2015-12-01 00:00:00
abstract:PREMISE OF THE STUDY:The evolutionary shift from radial to bilateral symmetry in flowers is generally associated with the evolution of low flower-size variation. This phenomenon supports the hypothesis that the lower size variation in bilateral flowers can be attributed to low pollinator diversity. In this study, we pr...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500371
更新日期:2015-12-01 00:00:00
abstract:PREMISE OF THE STUDY:Subtribe Hakeinae (526 spp.) represents a large Australian plant radiation central to our understanding of that flora's evolution and ecology. It contains Grevillea-the third largest plant genus in Australia and a group inferred to have among the highest diversification rates in the angiosperms. Ho...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500195
更新日期:2015-10-01 00:00:00
abstract:PREMISE OF THE STUDY:A knowledge of pollen characters in early-diverging angiosperm lineages is essential for understanding pollen evolution and the role of pollen in angiosperm diversification. In this paper, we report and synthesize data on mature pollen and pollen ontogeny from all genera of Nymphaeales within a com...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500249
更新日期:2015-10-01 00:00:00
abstract:PREMISE OF THE STUDY:To enhance our knowledge of the diversity of microalgae, a phycological survey of the Canary Islands (Spain) was undertaken. Here we report the discovery of a (semi)terrestrial green filamentous alga isolated from a steep volcanic canyon on La Palma. This alga is continually exposed to changing wea...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500199
更新日期:2015-09-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Mountainous regions support high plant productivity, diversity, and endemism, yet are highly vulnerable to climate change. Historical records and model predictions show increasing temperatures across high elevation regions including the Southern Rocky Mountains, which can have a stron...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500156
更新日期:2015-08-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Contact zones between diploids and their autopolyploid descendants represent a unique evolutionary venue for studying polyploid establishment, cytotype coexistence, and interactions. Here, we examine cytotype coexistence in a diploid-tetraploid contact zone of a perennial herb, Cardam...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500052
更新日期:2015-08-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Flower color is one of the best-studied floral traits in terms of its genetic basis and ecological significance, yet few studies have examined the processes that shape its evolution across deep timescales. Advances in comparative methods along with larger phylogenies for floral radiat...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500163
更新日期:2015-07-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Accurate assessments of biodiversity are paramount for understanding ecosystem processes and adaptation to change. Invasive species often contribute substantially to local biodiversity; correctly identifying and distinguishing invaders is thus necessary to assess their potential impac...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400466
更新日期:2015-07-01 00:00:00
abstract:PREMISE OF THE STUDY:Phylogenetic and morphological studies have helped clarify the systematics of large and complex groups such as the tribe Crotoneae (Euphorbiaceae). However, very little is known about the diversity, structure, and function of anatomical features in this tribe. Crotoneae comprises the species-rich p...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500017
更新日期:2015-06-01 00:00:00
abstract:PREMISE OF THE STUDY:One explanation for the evolution of selfing, the drought escape hypothesis, proposes that self-fertilization may evolve under conditions of intensifying seasonal drought as part of a suite of traits that enable plants to accelerate the completion of their life cycle, thereby escaping late-season d...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400557
更新日期:2015-06-01 00:00:00
abstract:PREMISE OF THE STUDY:Herbivory can affect a plant's fitness in a variety of ways, including modifying the biotic interactions of the plant. In particular, when herbivory influences floral display, we hypothesize that pollinator visitation will be altered accordingly. Here we studied the indirect effects of feeding by t...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500043
更新日期:2015-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Generic boundaries and infrageneric relationships among the charismatic temperate magnoliid Asarum sensu lato (Aristolochiaceae) have long been uncertain. Previous molecular phylogenetic analyses used either plastid or nuclear loci alone and varied greatly in their taxonomic implications for the ge...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400316
更新日期:2015-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Phylogenetic incongruence between "gene trees" and "species trees" has been widely acknowledged in phylogenetic research. Conflicts may emerge from several processes including paralogy, hybridization, and incomplete lineage sorting. Although phylogenetic incongruence appears common, its impact on m...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400527
更新日期:2015-04-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:The question why leaf dimensions vary so much between species has long puzzled ecologists. Presumably, variation arises from selective forces acting on leaf function but which selective forces and which leaf functions? This investigation assesses the consistency of divergence in plant...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400379
更新日期:2015-03-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Island plants are over-exploited and "under-explored." Understanding the reproductive biology of plants, especially rare species, is fundamental to clarifying their evolution, estimating potential for change, and for creating effective conservation plans. Clarification of sexual syste...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400486
更新日期:2015-03-01 00:00:00
abstract:PREMISE OF THE STUDY:Documented fossil floras in the neotropics are sparse, yet their records provide evidence on the spatial and temporal occurrence of taxa, allowing for testing of biogeographical and diversification scenarios on individual lineages. A new fossil Piper from the Late Cretaceous of Colombia is describe...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400427
更新日期:2015-02-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:The ability to respond to environmental change via phenotypic plasticity may be important for plants experiencing disturbances such as climate change and plant invasion. Responding to belowground competition through root plasticity may allow native plants to persist in highly invaded ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400234
更新日期:2015-01-01 00:00:00
abstract::There have been three periods of significant discovery in the exploration of fern and lycophyte genetics. First, during the 1930s, Andersson-Kottö conducted crossing studies on ferns. The publication of Manton's magnum opus on fern chromosomes in 1950 stimulated the second. The third emerged from Klekowski's 1973 Amer...
journal_title:American journal of botany
pub_type: 杂志文章,评审
doi:10.3732/ajb.1400317
更新日期:2014-12-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Two ovulate conifer cones, one of which is attached terminally to a short leafy shoot, reveal the presence of a new species of Hughmillerites in the Early Cretaceous Apple Bay flora of Vancouver Island, British Columbia, Canada. This ancient conifer expands the diversity of Cupressace...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400369
更新日期:2014-12-01 00:00:00
abstract:PREMISE OF THE STUDY:The life histories of lichen fungi are not well known and cannot be readily studied in laboratory culture. This work documents in situ the complete life cycle of the widespread crustose lichen Calopadia puiggarii, which reproduces sexually and asexually on the surfaces of leaves. METHODS:Plastic c...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400272
更新日期:2014-11-01 00:00:00
abstract:PREMISE OF THE STUDY:Reintroductions may be essential to prevent extinction of many critically endangered species. Ideally, reintroduction efforts rely on adjacent source populations, but limited source material may necessitate crossing individuals from different and possibly distant populations. To determine the conse...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400271
更新日期:2014-11-01 00:00:00
abstract::The timing, geographical locations, causes, and consequences of crop domestication have long been major concerns of archaeologists, and agricultural origins and dispersals are currently more relevant than ever to scientists seeking solutions to elusive problems involving food insecurity and global health disparities. ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400145
更新日期:2014-10-01 00:00:00
abstract::Perennial crops represent important fresh and processed food sources worldwide, but advancements in breeding perennials are often impeded due to their very nature. The perennial crops we rely on most for food take several years to reach production maturity and require large spaces to grow, which make breeding new cult...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400143
更新日期:2014-10-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:The evolution of invasiveness has been extensively studied in natural ecosystems; however, far less is known about the evolution of agricultural invasiveness, despite the major economic impact of weeds on crop productivity. Examining the population structure of recently arisen weeds c...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400064
更新日期:2014-10-01 00:00:00
abstract::Phloem, as a major tissue mediating long-distance communication, has been an object of extensive research ever since its structure was first reported in 1837. Functional phloem consists of sieve elements (SEs) and companion cells (CCs). While SEs are enucleated conducting cells in the phloem, CCs are cells with intact...
journal_title:American journal of botany
pub_type: 杂志文章,评审
doi:10.3732/ajb.1400197
更新日期:2014-09-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Adansonia digitata L. is one of the most important indigenous fruit trees of mainland Africa. Despite its significance for subsistence and income generation of local communities, little is known about the genetic and morphological variability of East African populations of A. digitata...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400198
更新日期:2014-09-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Floral traits play important roles in pollinator attraction and defense against floral herbivory. However, plants may experience trade-offs between conspicuousness to pollinators and herbivore attraction. Comparative studies provide an excellent framework to examine the role of multip...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400171
更新日期:2014-08-01 00:00:00
abstract::• Premise of the study: Carpel closure is commonly considered as a key innovation in angiosperms; however, some families continue to exhibit a variety of forms of incomplete carpel closure. The carpel of Sagittaria species contains an unusual structure. In this study, we confirm the closure type of the carpel of Sagit...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400172
更新日期:2014-07-01 00:00:00
abstract::• Premise of the study: Tropical forests are the most species-rich terrestrial communities on Earth, and understory trees and shrubs comprise a large fraction of their plant species diversity, especially at high rainfalls. The mechanisms responsible for generating such high levels of diversity remain unknown. One hypo...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1300460
更新日期:2014-07-01 00:00:00
abstract::• Premise of the study: Wild populations of domesticated species constitute a genetic reservoir and are fundamental to the evolutionary potential of species. Wild papaya (Carica papaya) is a rare, short-lived, gap-colonizing, dioecious tree that persists in the forest by continuous dispersal. Theoretically, these life...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400051
更新日期:2014-07-01 00:00:00
abstract::• Premise of the study: The mechanical properties of a plant are key variables governing the interaction between the plant and its environment. Thus, measuring variables such as the flexural rigidity (bending) of a plant element is necessary to understand and predict the plant-flow interaction. However, plant elements...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400163
更新日期:2014-06-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:The growth limitation hypothesis (GLH) is the most accepted mechanistic explanation for treeline formation, although it is still uncertain whether it applies across taxa. The successful establishment of Pinus contorta--an exotic conifer species in the southern hemisphere--above the No...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400166
更新日期:2014-05-01 00:00:00
abstract::Although theory has demonstrated rather low levels of gene flow are sufficient to counteract opposing mutation, drift, and selection, widespread recognition of the evolutionary importance of gene flow has come slowly. The perceived role of gene flow as an evolutionary force has vacillated over the last century. In the...
journal_title:American journal of botany
pub_type: 杂志文章,评审
doi:10.3732/ajb.1400024
更新日期:2014-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Within the Hypnales-the most derived and species-rich order of pleurocarpous mosses - phylogenies at or below the family level often show poor resolution. In preparation for a phylogeny of the genus Plagiothecium, we wished to identify the DNA markers best suited for evolutionary reconstruction in ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1300269
更新日期:2014-04-01 00:00:00
abstract::Serpentine soils are a model system for the study of plant adaptation, speciation, and species interactions. Serpentine soil is an edaphically stressful, low productivity soil type that hosts stunted vegetation and a spectacular level of plant endemism. One of the first papers on serpentine plant endemism was by Arthu...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1300349
更新日期:2014-02-01 00:00:00