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：:Seed size and germination requirements of eight (of nine) Sarracenia species, and 13 populations of S. purpurea were studied. All species except for S. purpurea are restricted to the southeastern United States, whereas S. purpurea ranges across Canada, southward along the eastern United States into Maryland and Virgin...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-03-01 00:00:00
abstract：:Phylogenetic relationships were inferred using nucleotide sequence variation of the nuclear-encoded chalcone synthase gene (Chs) and the chloroplast gene matK for members of five tribes from the family Brassicaceae to analyze tribal and subtribal structures. Phylogenetic trees from individual data sets are mostly in c...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-03-01 00:00:00
abstract：:The relationship between near-infrared reflectance at 800 nm (NIRR) from leaves and characteristics of leaf structure known to affect photosynthesis was investigated in 48 species of alpine angiosperms. This wavelength was selected to discriminate the effects of leaf structure vs. chemical or water content on leaf ref...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-02-01 00:00:00
abstract：:The FAD2-1 microsomal omega-6 desaturase gene contains a large intron ( approximately 1133 bp [base pairs]) in the 5' untranslated region that may participate in gene regulation and, in GOSSYPIUM:, is evolving at an evolutionary rate useful for elucidating recently diverged lineages. FAD2-1 is single copy in diploid G...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-01-01 00:00:00
abstract：:Fluorescence in situ hybridization (FISH) of a large-insert genomic clone, BAC 22B2, previously suggested that Sorghum bicolor (2n = 20) has the tetraploid architecture A(b)A(b)B(b)B(b). Here, we report on BAC 22B2 subclone pCEN38 (1047-bp insert) as related to sorghum and sugarcane. Mitotic FISH of six different subc...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-12-01 00:00:00
abstract：:The interaction between simulated cotyledon herbivory and interspecific competition was studied in a greenhouse experiment using two species of trees, Acer rubrum and Quercus palustris, which commonly invade abandoned agricultural fields. Herbivory treatments were applied as a gradient of cotyledon removal for A. rubr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-12-01 00:00:00
abstract：:The desert moss Syntrichia caninervis exhibits one of the most skewed sex ratios in the plant kingdom, with female individuals far outnumbering male individuals (exceeding 14♀:1♂). The "cost of sex hypothesis" derives from allocational theory and predicts that the sex which is most expensive should be the rarer sex. T...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-11-01 00:00:00
abstract：:Herbivore damage is known to cause the premature loss of mature leaves. However, the effects of herbivory on abscission during the early stages of leaf development remain unexplored, even though herbivores frequently prefer unlignified, immature leaves. In a field experiment, we removed 50% of the tissue from leaves a...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-11-01 00:00:00
abstract：:The mode of chloroplast DNA (cpDNA) inheritance was investigated in the genus Larrea (Zygophyllaceae) by polymerase chain reaction (PCR) amplification of cpDNA fragments using three pairs of chloroplast universal primers. A total of 20 F(1)s from interspecific crosses among five different taxa in the section Bifolium ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-10-01 00:00:00
abstract：:We studied 15 riparian and upland Sonoran desert species to evaluate how the limitation of xylem pressure (Ψ(x)) by cavitation corresponded with plant distribution along a moisture gradient. Riparian species were obligate riparian trees (Fraxinus velutina, Populus fremontii, and Salix gooddingii), native shrubs (Bacch...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-09-01 00:00:00
abstract：:The possible pathways of origin of two recently arisen introgressant forms of Senecio vulgaris (i.e., var. hibernicus and York radiate groundsel) were investigated in experimental crosses between tetraploid S. vulgaris var. vulgaris and the normally diploid S. squalidus. Comparison of the morphology of synthesized hyb...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-08-01 00:00:00
abstract：:Cleistogamous capitula formed by Centaurea melitensis display a number of morphological and functional changes with respect to chasmogamous capitula that ensure self-fertilization. Because no studies have hitherto addressed the evolution of cleistogamy in Asteraceae, it was considered useful to ascertain whether these...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-07-01 00:00:00
abstract：:Phylogenetic relationships of 38 species of the Alibertia group (Rubiaceae) and two outgroup species were investigated using the nuclear ribosomal 5S nontranscribed spacer (5S-NTS) and the internal transcribed spacers (ITS). Analysis of the data sets separately and in combination resulted in several well-supported and...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-07-01 00:00:00
abstract：:Hybridization and introgression play important roles in plant evolution, and their occurrence on the oceanic islands provides good examples of plant speciation and diversification. Restriction fragment length polymorphisms (RFLPs) and trnL (UAA) 3'exon-trnF (GAA) intergenic spacer (IGS) sequences of chloroplast DNA (c...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-06-01 00:00:00
abstract：:Nuphar comprises 13 species of aquatic perennials distributed in the temperate Northern Hemisphere. The European species N. lutea and N. pumila in Norway, the Netherlands, and Germany are pollinated by bees and flies, including apparent Nuphar specialists. This contrasts with reports of predominant beetle pollination ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-06-01 00:00:00
abstract：:The selective maintenance of gynodioecy depends on the relative fitness of the male-sterile (female) and hermaphroditic morphs. Females may compensate for their loss of male fitness by reallocating resources from male function (pollen production and pollinator attraction) to female function (seeds and fruits), thus in...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-05-01 00:00:00
abstract：:Microscopic structures (petrofilaments) may develop during palynological laboratory processing procedures that are superficially similar to secondary wall thickenings and elaters. These filaments form from angular bodies that resemble fungal spores and resin bodies. The angular bodies are a type of hydrocarbon called ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-05-01 00:00:00
abstract：:We investigated patterns of fruit and seed production on inflorescences of a population of Pancratium maritimum in northwest Spain over a 2-yr period. Initial findings showed that the earliest opening flowers on an inflorescence are more likely to set fruit and produce more seeds than later opening flowers and that th...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-04-01 00:00:00
abstract：:Several alpine species have outlying populations in the lowlands and lower mountains north of the Alps. These small, isolated populations are usually described as either (1) glacial relics, (2) descendants from populations living on forelands and moraines during the ice ages, or (3) populations founded by long-distanc...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-04-01 00:00:00
abstract：:Iris cristata and I. lacustris differ markedly in geographic distribution, glacial history of current ranges, and ecology. We hypothesized that I. cristata, a widespread species of unglaciated regions of eastern North America, would exhibit genetic diversity typical of other widespread plant species, whereas the threa...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-03-01 00:00:00
abstract：:In a wet oligotrophic meadow located in the Czech Republic, a factorial experiment with treatments consisting of fertilization, mowing, and removal of the dominant species (Molinia caerulea) was established in 1994. In 1997 Holcus lanatus, Molinia caerulea, Potentilla erecta, Prunella vulgaris, and Ranunculus auricomu...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-03-01 00:00:00
abstract：:Yucca glauca is a C(3) evergreen rosette species locally common in the C(4)-dominated grasslands of the central Great Plains. Most congeners of Y. glauca are found in deserts, and Y. glauca's morphological similarities to desert species (steeply angled leaves, evergreen habit) may be critical to its success in grassla...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-02-01 00:00:00
abstract：:Seed mass is considered to be the least plastic component of reproductive yield. Yet, in invasive populations of garlic mustard, Alliaria petiolata, seed mass was highly variable (eightfold among populations, 2.5-7.5 fold within populations, two-threefold within individuals, and 1.4-1.8 fold within fruits). Variation ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-01-01 00:00:00
abstract：:During the crown-building phase, the mechanical architecture of the trunk of Aralia spinosa exhibits considerable ontogenetic variation. All trunks were tapered along their length, and taper was dependent on both ramet size and age; older, larger trunks were more tapered than younger, smaller trunks. Trunk specific gr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-12-01 00:00:00
abstract：:Reproductive traits of tropical tree species vary predictably in relation to successional stage, but this variation may be due to the species' phylogenetic histories rather than selective pressures imposed by regeneration requirements. Reproductive phenology, tree size at the onset of reproduction, and fecundity of 11...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-12-01 00:00:00
abstract：:In the southern Appalachian mountains a subcanopy species, Rhododendron maximum, inhibits the establishment and survival of canopy tree seedlings. One of the mechanisms by which seedlings could be inhibited is an allelopathic effect of decomposing litter or leachate from the canopy of R. maximum (R.m.) on seed germina...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-11-01 00:00:00
abstract：:The pitchers of the tropical carnivorous plant Nepenthes alata are highly specialized organs for the attraction and capture of insects and absorption of nutrients from them. This study examined the structure and development of these pitchers, with particular focus on the nectaries and digestive glands. Immature pitche...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-10-01 00:00:00
abstract：:Genetic diversity at variable-number-tandem-repeat (VNTR) loci was examined in the common cattail, Typha latifolia (Typhaceae), using three synthetic DNA probes composed of tandemly repeated "core" sequences (GACA, GATA, and GCAC). The principal objectives of this investigation were to determine whether: (1) the previ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-09-01 00:00:00
abstract：:Cladistic analyses of plastid DNA sequences rbcL and trnL-F are presented separately and combined for 48 genera of Amaryllidaceae and 29 genera of related asparagalean families. The combined analysis is the most highly resolved of the three and provides good support for the monophyly of Amaryllidaceae and indicates Ag...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-09-01 00:00:00
abstract：:Individual plants of Asclepias exaltata (Asclepiadaceae) typically express an unusual self-incompatibility system under single-gene control. Hand-pollinations performed in six natural populations detected occasional self-fertile plants. The frequency of self-fertile individuals ranged from 0 to 34.0% and differed sign...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-08-01 00:00:00
abstract：:Megaspore and microspore massulae of Paleoazolla patagonica gen. et sp. nov. are described from the Upper Cretaceous of La Colonia Formation, Chubut Province, Argentina. The new fern possesses megaspore complexes with three to four glochidiate floats attached directly to the megaspore; a columella-like structure appea...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-08-01 00:00:00
abstract：:Many plant species contain populations with more than one polyploid cytotype, but little is known of the mechanisms maintaining several cytotypes in a population. Andropogon gerardii cytotypes were compared to evaluate different models of autopolyploid cytotype coexistence. The enneaploid (90 chromosome, 9x) cytotype ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-07-01 00:00:00
abstract：:A detailed study of ascomal morphology and development in Cercophora palmicola showed that ontogeny is ascohymeniaceous, giving rise to an ostiolate perithecium. Ascomal initials consist of a coiled ascogonium surrounded by several layers of hyphae whose cells become pseudoparenchymatous. The centrum of the young asco...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-06-01 00:00:00
abstract：:We present here the first molecular phylogeny of tribe Diseae (Orchidoideae: Orchidaceae). Nuclear ribosomal ITS1, 5.8S rDNA, and ITS2 sequences were compared for 30 Diseae, 20 Orchideae, and four Cranichideae and Diurideae outgroups. ITS - rDNA sequences exhibited a transition:transversion ratio of 1.3 and extensive ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-06-01 00:00:00
abstract：:Pinus rzedowskii is an endangered pine species from Michoacán (central México), which has been previously reported from only three localities. Classified within the subgenus Strobus, it exhibits intermediate morphological characters between subgenera Strobus and Pinus. We analyzed genetic aspects that could shed light...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-05-01 00:00:00
abstract：:We examined the function of floral traits associated with buzz pollination through studies of Rhexia virginica (Melastomataceae) in the Muskoka region of Ontario, Canada. Controlled pollinations demonstrated that the species is self-compatible, but dependent on insects for pollen transfer. Bumble bees made 82 and 90% ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-04-01 00:00:00
abstract：:Phylogenetic relationships among embryophytes (tracheophytes, mosses, liverworts, and hornworts) were examined using 21 newly generated mitochondrial small-subunit (19S) rDNA sequences. The "core" 19S rDNA contained more phylogenetically informative sites and lower homoplasy than either nuclear 18S or plastid 16S rDNA...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-03-01 00:00:00
abstract：:Cladistic parsimony analyses of rbcL nucleotide sequence data from 171 taxa representing nearly all tribes and subtribes of Orchidaceae are presented here. These analyses divide the family into five primary monophyletic clades: apostasioid, cypripedioid, vanilloid, orchidoid, and epidendroid orchids, arranged in that ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-02-01 00:00:00
abstract：:Intensified ultraviolet-B radiation or UV-B (wavelengths between 280 and 320 nm) can delay flowering and diminish lifetime flower production in a few plants. Here we studied the effects of enhanced UV-B on floral traits crucial to pollination and pollinator reproduction. We observed simultaneous flowering responses of...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-01-01 00:00:00
abstract：:A well-integrated plant shows extensive carbohydrate translocation through the plant body. Even in highly integrated plants, however, translocation patterns will be sectorial if vascular tissue restricts carbon movement to sectors along stems. Both integration and sectorial translocation patterns are sensitive to plan...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1998-12-01 00:00:00
