首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
For generations scholars have explained the marked difference in the ruins of Chichén Itzá by attributing the southern buildings to indigenous Yucatecan Maya and then telling of central Mexican Toltec invaders who built (or forced the Maya to build) the Tula-like plaza to the north. But evidence now suggests that the infamous "Toltec conquest of the Maya" never happened. The story may actually be the manifestation of a Western tendency to express ambivalent attitudes toward Native Americans in terms of polar opposites, in this case, "gentle Maya priests" versus "brutal Mexican warriors." In the end, the story may reveal more about the Western politics of knowledge than about pre-Columbian Mesoamerican history.  相似文献   

2.
3.
Ochtodes searlesii Mendoza‐González, Mateo‐Cid et Sentíes sp. nov. is described from Michoacán, tropical Mexican Pacific, on the basis of comparative morphology and rbcL sequence analysis. It is distinguished from other Ochtodes species by its erect axes arising from an encrusting base, its small terete fronds, regularly dichotomously branched axes, and obliquely divided zonate tetrasporangia. Phylogenetic analyses showed that three Pacific Mexican samples, from Caletilla, Zapote and La Majahuita (Michoacán), were identical and formed a distinctive and well supported Clade segregated from other species of Ochtodes from Brazil, Cuba, Ecuador, Guadeloupe and Mexico. The Mexican entity is morphologically distinct from other Ochtodes species as well. On this basis we propose a new Ochtodes species.  相似文献   

4.
IntroducciónLos accidentes causados por animales venenosos ocurren con mucha frecuencia en comunidades pobres con acceso limitado a los servicios de salud. Se les consideran enfermedades desatendidas y son una de las causas importantes de morbimortalidad en varias naciones del mundo, incluida Venezuela.ObjetivoEvaluar la mortalidad por contacto traumático con animales venenosos (serie X20-X29) en Venezuela en el periodo de 2000 a 2009.Materiales y métodosLos datos se obtuvieron de los anuarios de mortalidad del Ministerio de Salud.ResultadosSe registraron 759 decesos, la mayoría de ellos en el 2009. La primera causa fue la mordedura de serpientes (n=323; 42,6%), seguida por la picadura de himenópteros (n=170; 22,4%), la mordedura de centípedos (n=106; 14,0%) y la picadura de escorpiones (n=76; 10,0%). La mediana de la tasa de mortalidad general para el periodo fue de 0,285 fallecidos por 100.000 habitantes, en tanto que, por grupo específico, fue de 0,120 para ofidios, de 0,065 para himenópteros, de 0,035 para centípedos y de 0,025 para escorpiones.ConclusiónAl comparar estos datos con los antecedentes históricos, se evidenció la modificación del patrón de mortalidad en el país caracterizada por un aumento significativo de los decesos por centípedos, tercera causa de muerte, lo que reubica la picadura de escorpiones como la cuarta causa de mortalidad.Palabras clave: serpientes, himenópteros, escorpiones, mortalidad, epidemiología  相似文献   

5.
Searching for the Secrets of Nature: The Life and Works of Dr. Francisco Hernández. Simon Varey. Rafael Chabrán. and Dora B. Weiner. eds. Stanford: Stanford University Press, 2000. xvi. 229 pp.
The Mexican Treasury: The Writings of Dr. Francisco Hernández. Simon Varey. ed. Rafael Chabrán. Cynthia L. Chamberlin. and Simon Varey. trans. Stanford: Stanford University Press, 2000. xix. 281 pp.  相似文献   

6.
An incomplete skeleton from Puesto Morales (Neuquén Province, Argentina) is described as a new species of sauropod, Zapalasaurus bonapartei. The unit that yielded the holotype of this dinosaur is the Piedra Parada Member of the La Amarga Formation, whose age is regarded as Barremian-lower Aptian. Several characters are interpreted as autapomorphies of Zapalasaurus bonapartei: cervical vertebrae with a lamina uniting the prezygapophysis and the zygapophyseal portion of the postzygodiapophyseal lamina, cervical vertebrae with the diapophyseal portion of the postzygodiapophyseal lamina reduced, cervical vertebrae with poorly developed spinoprezygapophyseal laminae, mid and posterior caudal vertebrae with anteroposteriorly elongated neural spines, whose anterodorsal corners are higher than their posterodorsal ones, and caudal centrum length doubles over first 20 vertebrae. Zapalasaurus bonapartei is considered as the sister group of the other diplodocoids (excluding Haplocanthosaurus). Diplodocoids were abundant in the Early Cretaceous, becoming extinct by the early Late Cretaceous. The record of Zapalasaurus bonapartei shows that, at least in the Neuquina Basin, basal diplodocoids were more diverse than previously thought.  相似文献   

7.
8.
As a Spanish-language broadcast programme based on a sympathetic Mexican character who also happens to be a drug kingpin, La Reina del Sur negotiates the perilous terrain of the European drug trade and an omnipresent hostility directed at Mexicans. As cable programmes with the industrial freedom to venture into spaces in between prosocial and antisocial, Weeds and Breaking Bad attempt to incorporate a more nuanced and culturally informed characterization of the Mexican drug dealer – one that notably impacts the relationship of the white protagonists to their new occupations as producers and dealers of illegal substances. These three series – produced independently of one another and distributed on three different networks – have crossed paths in a manner that can be revealed through the intricacies of a controversial and complex cultural artifact: the narcocorrido.  相似文献   

9.
Summary The occurrence of 2n pollen-producing plants was investigated in 187 plant introductions (PIs) of 38 wild species of tuber-bearing Solanum. These 2x, 4x, and 6x species are from Mexico, and Central and South America. The determination of 2n pollen-producing plants was conducted using acetocarmine glycerol. Plants with more than 1% large-size pollen were regarded as 2n pollen-producing plants. 2n pollen-producing plants were identified in the following species: 10 out of 12 Mexican 2x species, seven of nine South American 2x species, seven of seven Mexican and Central American 4x species, five of five South American 4x species, and five of five Mexican 6x species. The frequency of 2n pollen-producing plants varied among species at the same ploidy level, but the range of frequency, generally between 2 and 10% among species, was similar over different ploidy levels. The general occurrence of 2n pollen in both 2x and polyploid species, which are evolutionarily related, is evidence that the mode of polyploidization in tuber-bearing Solanums is sexual polyploidization. Furthermore, the frequencies of 2n pollen-producing plants in autogamous disomic polyploid species were not markably different from those of their related diploid species. It is thought that the frequent occurrence of 2n gametes with autogamy tends to disturb the fertility and consequently reduce fitness of polyploids. Thus, we propose that the breeding behavior of polyploids and the occurrence of 2n gametes may be genetically balanced in order to conserve high fitness in polyploid species in tuberbearing Solanum.Paper No. 3114 from the Laboratory of Genetics. Research supported by the College of Agriculture and Life Sciences; International Potato Center; USDA, SEA, CGRO 84-CRCR-1-1389; and Frito Lay, Inc.  相似文献   

10.
Politics and Privilege in a Mexican City. Richard R. Fagen and William S. Tuohy
Being Indian in Hueyapan: A Study of Forced Identity in Contemporary Mexico. Judith Friedlander .
Panajachel: A Guatemalan Town in Thirty-Year Perspective. Robert E. Hinshaw .
Población y sociedad: Cuatro comunidades del Acolhuacan. Marisol Pérez Lizaur .
Princes of the Earth: Subcultural Diversity in a Mexican Municipality. Barbara Luise Margolies .
Servants of the Saints: The Social and Cultural Identity of a Tarascan Community in Mexico.  相似文献   

11.
ABSTRACT.   Worthen's Sparrows ( Spizella wortheni ) are endemic to the Mexican Plateau and have been listed as globally endangered. The breeding biology of these sparrows is poorly understood, and nesting is only known to occur at three locations (Las Esperanzas, Nuevo León, and La India and Tanque de Emergencia, Coahuila). In June and July 2006, we searched for nests of  Worthen's Sparrows and located three new breeding localities: La Carbonera and San Rafael in the state of Nuevo León, and San José del Alamito in the state of Coahuila. We subsequently sampled vegetation where nests were located and, on 26 August 2006, conducted surveys along 1-km transects at the three new breeding locations as well as at El Erial-La Casita, Nuevo León. We recorded the most Worthen's Sparrows at El Erial-La Casita ( N = 33), followed by San José del Alamito ( N = 9), San Rafael ( N = 6), and La Carbonera ( N = 3). No nests were located at El Erial-La Casita, but small groups of sparrows that included juveniles were observed. At the three breeding locations, shrub strata were dominated by tarbush ( Flourensia cernua ; San José del Alamito and La Carbonera) and Berlandier's wolfberry ( Lycium berlandieri ; San Rafael). Most (68%) recently recorded nests for this species have been found in tarbush. Historical and recent data (including our study) suggest that Worthen's Sparrows typically breed in grassland habitat where shrubs of some type are also present. Because conversion of land to agriculture continues to be a major threat to grasslands in northeastern Mexico, we recommend that conservation efforts be implemented to protect the known breeding areas of Worthen's Sparrow.  相似文献   

12.
RÉSUMÉ. Une nouvelle microsporidie, Ormieresia carcini gen. n., sp. n., est trouvée dans Carcinus mediterraneus Czerniavsky, 1884. Son évolution et ses ultrastructures sont étudiees.
Le cycle débute par un méronte limité par une membrane unitaire et possédant un diplocaryon. Toute la sporogonie se déroule dans la musculature de l'höte. Les stades sporogoniaux sont enveloppés dans une membrane pansporoblastique persistante. Dans chaque pansporoblaste, la sporoblastogenése (donnant naissance à 8 sporoblastes) est particulière; un plasmode sporogonial octonucléé manque. Au cours des divisions schizogoniques et sporogoniques, chaque centre cinétique est formé de 2 plaques, une incluse dans l'enveloppe nucléaire, l'autre occupant une position extranucléaire. Les sporontes en division et les sporoblastes sécrètent des substances métaboliques (granules, tubes) qui sont déposées dans l'espace pansporoblastique.
La spore uninucléée est longue et cylindrique (19,1 × 2,4 μm). Un manubrium rectiligne traverse la spore. Son extrémité postérieure se rétrécit brusquement en un filament polaire décrlvant 4 ou 5 tours de spire. L'extrémité antérieure du manubrium est attachée au capuchon polaire lui-même comprimé par un double anneau. La partie antérieure du manubrium est entourée par un polaroplaste formé d'une zone spongieuse et d'une zone lamellaire.  相似文献   

13.
Naiadocystis phykoterion n. gen., n. sp. (Apicomplexa: Eugregarinida: Hirmocystidae), is described from the Mexican pygmy grasshopper, Paratettix mexicanus (Orthoptera: Tetrigidae), collected from sandbars along Harmon Creek, Walker County, Texas, in the western edge of the Texas Big Thicket. Naiadocystis n. gen. is distinguished by the form of the epimerite complex, a simple cordoid or toroid epimerite with an interior obconoid structure resembling a funnel that tapers to a distinct axial canal bisecting the protomerite, which is conspicuous in all stages of development, and a satellite protomerite reduced to a linearly crateriform cup or sucker that receives and enfolds posterior end of primite deutomerite. Association is precocious, caudofrontal, and biassociative. Gametocysts are spherical. Sporoducts are present but vestigial and irregular in number. Oocysts are broadly elliptoid with 4 small spherical polar knobs, 1 each at 30 degrees, 150 degrees, 210 degrees, and 330 degrees, and dehisce en masse. The species described herein are differentiated by their overall size and relative proportion of cellular structures. Naiadocystis acantholobae (Hoshide, 1952) n. comb., Naiadocystis acrydiinarum (Semans, 1939) n. comb., and Naiadocystis tetrigis (Corbel, 1968) n. comb. are recognized as members of Naiadocystis previously placed within Gregarina (Apicomplexa: Eugregarinida: Gregarinidae).  相似文献   

14.
In the Museum of Maya Culture: Touring Chichén Itzá. Quetzil E. Castañeda. Minneapolis: University of Minnesota Press, 1996.341 pp.  相似文献   

15.
La encefalopatía hipóxico-isquémica es una causa frecuente e importante de daño neurológico en recién nacidos a término y prematuros. Un evento centinela de esta condición es la vasa previa, específicamente cuando existe anormalidad de la placenta como la inserción “velamentosa” del cordón umbilical. Algunos reportes evidencian la asociación entre estas dos condiciones, pero son escasos los que dan cuenta del proceso de recuperación y del pronóstico neurológico de los niños afectados por ellas.Se presenta el caso de un paciente, con antecedentes de inserción “velamentosa” del cordón umbilical y encefalopatía hipóxico-isquémica, que recibió hipotermia terapéutica (cool cap). Se describe su proceso de rehabilitación neurológica y se calculó el porcentaje de probabilidad de presentar esta condición frente a la población sin estos factores. El niño tenía cinco años y el puntaje en su prueba de Apgar fue de 0 al minuto y de 2 a los 15 minutos. Desarrolló encefalopatía hipóxico-isquémica grave secundaria a una inserción “velamentosa” del cordón umbilical sin diagnóstico prenatal, con gran compromiso neurológico y multisistémico inicial. El proceso de recuperación incluyó el manejo inicial multidisciplinario en la unidad de cuidados intensivos neonatales y el inicio temprano de habilitación neurológica.Hoy el niño está escolarizado y en terapia integral, no presenta deficiencias motoras ni sensoriales en el examen físico, aunque la prueba neuropsicológica sugiere un riesgo de trastorno por déficit de atención e hiperactividad. Habitualmente, los niños con encefalopatía hipóxico-isquémica grave presentan discapacidad por deficiencias motoras, cognitivas o conductuales. El haber recibido hipotermia terapéutica y un manejo estructurado de rehabilitación redujo en gran medida las deficiencias esperadas y ha promovido un satisfactorio desarrollo físico y neurológico.Palabras clave: cordón umbilical, hipoxia-isquemia encefálica, hipotermia inducida, rehabilitación neurológica  相似文献   

16.
This article discusses the change among Yucatec Maya farmers from traditional shifting milpa agriculture to intensive horticultural production for the Mexican market. The process of agricultural intensification among this group of peasant farmers has involved movement toward an increasingly sedentary form of production which has heightened reliance on the use of chemicals with negative consequences for the environment. The research, which focuses on the pressure on producers to abandon more sustainable forms of cultural controls against crop loss in favor of modern chemical controls, raises the issue of the transferability of sustainable traditional technology to small commercial farmers in the tropics. More specifically, the article draws attention to the sometimes overlooked issue of economic, as well as environmental, sustainability in discussions on agricultural development and resource management.Parts of this article were presented at the 89th Annual Meeting of the American Anthropological Association in New Orleans in November 1990, as well as at a conference in Mérida in Yucatan entitled La modernización de la milpa en Yucatán: utopía o realidad in May 1991.  相似文献   

17.
The Other Struggle for Equal Schools: Mexican Americans during the Civil Rights Era. Rubén Donate. Albany: State University of New York Press, 1997. 210 pp.  相似文献   

18.
19.
Two species of nematodes, Angiostoma coloaense n. sp. and Aulacnema monodelphis n. g., n. sp. (Angiostomatidae: Rhabditida) are described from terrestrial molluscs of Vietnam. Both species are characterised by a long bowl-shaped buccal cavity and typically angiostomatid male bursal alae, spicules and gubernaculum. The new genus, Aulacnema n. g., is erected for the first reported monodelphic angiostomatid. Angiostoma coloaense n. sp. can be distinguished from other species of Angiostoma Dujardin, 1845 by having a buccal cavity length greater than its width and the absence of tail spikes on both males and females.  相似文献   

20.
Mexico has the largest number of leporid species in the world but most have been little studied. The endemic Mexican cottontailSylvilagus cunicularius (Waterhouse, 1848) is the largest Mexican rabbit, and although not in danger of extinction, it is increasingly threatened. Since little is known about its annual pattern of reproduction, we studied this species in La Malinche National Park, central Mexico, whereS. cunicularius is still common. For 7 years we trapped and marked 157 different individuals (plus 59, sometimes multiple, re-captures), determining across the year the percent of adult females that were reproductively active, the number of juveniles as a percent of total captures, and the percent of males with scrotal testes. Reproductively active females were present throughout the year but with a notable peak from March to October, juveniles were present throughout the year but with a peak from September to December, and adult males had scrotal testes throughout the year with no seasonal change in testis length. Onset of the breeding season coincided with increasing day length and temperature, and births with high rainfall. Thus, in central MexicoS. cunicularius breeds throughout the year but particularly during the warmer, wetter summer months. We therefore recommend that hunting only be permitted from November to February.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号