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981.
A F Tarantal 《Journal of medical primatology》1990,19(1):47-58
Similarities in developmental biology between human and nonhuman primates have resulted in the use of macaque species as models in perinatal research. Studies have frequently included invasive surgical procedures or may have required "blind" injections. Several techniques have been established in human subjects using ultrasound as a guide such as cordocentesis and fetal therapy. These techniques have been applied to the nonhuman primate laboratory setting, which significantly decreases the risk of pregnancy loss due to experimental intervention. 相似文献
982.
A. A. Aleem 《Hydrobiologia》1990,208(1-2):7-15
Transgression on marine habitats (seagrass beds, coral reefs and mangrove stands) along the Jeddah coast and adjacent lagoons, owing to increased human activity, resulted in regression, degeneration or substitution of plant and animal communities.The effect of organic and thermal pollution on benthic life is examined. A need for baseline studies on such habitats is stressed for the identification and conservation of endangered biota. 相似文献
983.
Summary The effect of Alternaria solani culture filtrate on adventitious shoot regeneration from tuber discs was evaluated using five potato cultivars, which were selected based on their field reaction to Alternaria solani and which represented a range of disease reactions. The culture filtrate stimulated regeneration, a response that could prove to be very useful in the wider utilization of transformation and in vitro selection technology.Research conducted at the Scottish Crop Research Institute during a transfer of work of the senior author 相似文献
984.
T Suzuki 《American journal of physical anthropology》1987,74(3):309-318
This report concerns a probable case of osteosarcoma found in a precontact Hawaiian skeleton from the east coast of Oahu Island, Hawaii. A young adult female showed a tumorous bone proliferation with a coarse, corallike appearance at the distal metaphyseal area of the left femur. In gross observation, a profusion of coalescing bone was extended to the surrounding space and also invaded the marrow space. X-ray films revealed spotted and ringed shadows in the shaft and a "sunburst appearance" in the lesion. Histological examination of the tumor bone fragment showed a great deal of primitive bone tissue formation without any systemic Haversian structure. The diagnosis of osteogenic osteosarcoma is much more compatible than other primary malignant bone tumors such as Ewing's sarcoma, fibrosarcoma, and chondrosarcoma or osteoplastic metastatic carcinoma of the bone when the location and morphology of the tumor are considered along with the age of the decedent. 相似文献
985.
986.
商平 《Acta Botanica Sinica》1987,(2)
本文报道了阜新盆地含煤地层中的植物化石和植物群特征,对植物化石在垂直方向上的变化规律进行了讨论。 相似文献
987.
云南省迪庆州更新世早期哺乳类化石的发现 总被引:7,自引:2,他引:5
本文简述横断山脉中段中甸尼西的哺乳类化石九种,能鉴定到种一级的只有1/3,其中(亻莫)鼠是新种. 相似文献
988.
本文记述了湖北南漳走马岭组上段的古鳖属—新种——沐浴古鳖 (Aspideretes muyuensis, sp. nov.),并对其分类位置和时代作了探讨.新种的主要特征是:背甲前、后缘平切;前椎板前部超出在第一对肋板内缘之前;第一对肋板与颈板之间有一对大的孔洞;椎板7块;肋板8对,最后两对在中线处左、右相遇;背甲纹饰较细小,腹甲表面光滑. 相似文献
989.
A fragmentary hominid cranium with teeth, specimen L.894-1, dating from 1.84 m.y. BP in the Shungura Formation at Omo, is described. From its dental and cranial morphology and because of similarities to Olduvai Hominids 24 and 13 and Sangiran 4, among others, it is concluded that the specimen represents a member of an early species of the genus Homo (Homo habilis or Homo modjokertensis). The specimen shows approximal grooving on the premolars, pre-mortem chipping of the molar enamel, foramina ovale and spinosum divided by the sphenosquamosal suture, limited pneumatization of the mastoid region, and a possible interparietal bone. Sedimentological, ostracod, pollen, macrofloral, and taphonomic data indicate that the paleo-environmental context was a savanna/grassland or savanna woodland on the margin of a saline lake. 相似文献
990.
Morphologic changes occurring during pollen grain activation and ultrastructural features of Lycopersicum peruvianum Mill. pollen tube during the first stages of growth in vitro have been studied. The more evident morphologic changes during activation, in comparison to those already described for mature inactive pollen, concern dictyosomes, rough endoplasmic reticulum (RER), and ribosomes. The dictyosomes are very abundant and produce large and small vesicles. Near the germinative pores both types of vesicles are present, while all along the remaining cell wall only the large type is observed. These latter react weakly to Thiéry's test and probably contain a callose precursor necessary for the deposition of a callosic layer lining at first only the inner side of the functioning pore and occasionally the other two pores, and subsequently the entire inner surface of the cell wall. The small vesicles, highly positive to Thiéry's test, are present only near the pores and could be involved in the formation of the pectocellulosic layer of the tube wall. The setting free of RER cisterns, which in the mature inactive pollen were aggregated in stacks, coinciding with polysome formation and resumption of protein synthesis, is in accord with the hypothesized role of RER cistern stacks as a reserve of synthesizing machinery. The pollen tube reaches a definitive spatial arrangement soon after the generative cell and vegetative nucleus have moved into it. At this stage four different zones that reflect a functional specialization are present. In the apical and subapical zone two types of dictysosome-originated vesicles, similar to those found in the activated pollen grain, are present. Their role in the formation of the callosic and pectocellulosic wall layers seems to be the same as in the activated pollen grain.Abbreviations ER
endoplasmic reticulum
- RER
rough endoplasmic reticulum
Research performed under CNR program Biology of Reproduction 相似文献