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1.
不同基质对一品红生长势的影响   总被引:2,自引:0,他引:2  
一品红是具有很强的观赏价值的花卉,它在圣诞前夕开花.花期可以覆盖圣诞、元旦、春节、情人节很受人们的喜爱。以草炭、珍珠岩、蛭石为主要栽培的基质。按不同成分和比例配制作无土配方,以园土作对照,进行一品红的盆栽试验。试验结果:不同处理对植株叶片数、株高、冠径、茎粗具有不同效应,差异显著;无土栽培优于园土栽培。4种无土基质配方中以草炭:珍珠=4:1的配比栽培效果最好。  相似文献   

2.
Measurement from Christmas Island (2 degrees N, 157 degrees W) of long-term mean vertical motions in the tropical atmosphere using very-high-frequency wind-profiling Doppler radar show that there is a transition from downward motion in the free troposphere to upward motion in the upper troposphere and lower stratosphere. The observations in the free troposphere are consistent with a balance between adiabatic and diabatic heating and cooling rates in a clear atmosphere. Comparison of the results at Christmas Island during El Ni?o and non-El Ni?o conditions with earlier results obtained for stratiform rain conditions over Pohnpei, Federated States of Micronesia, show that cirrus clouds in the vicinity of the tropopause likely play an important role in determining the sense and magnitude of vertical motions in this region. These results have implications for the exchange of mass between the troposphere and stratosphere over the tropics.  相似文献   

3.
Cardiac atria of BIO 14.6 hamsters are deficient in natriuretic factor   总被引:7,自引:0,他引:7  
The hearts of 220-day-old hamsters of the BIO 14.6 strain are deficient in atrial natriuretic factor; saline extracts of atria produce one-third the natriuretic and diuretic effects of extracts of atria from age-matched normal hamsters. BIO 14.6 hamsters are known to develop congestive heart failure with edema when they are about 200 days old, and the venous congestion and edema are preventable by parabiosis with normal hamsters. The humoral mediator, the deficiency of which causes venous congestion and edema in BIO 14.6 hamsters, may be atrial natriuretic factor.  相似文献   

4.
Hemophilia A: polymorphism detectable by a factor 8 antibody   总被引:7,自引:0,他引:7  
Plasma from 54 patients with hemophilia A was tested for neutralizing activity with a human antibody to factor VIII. The plasma from 52 patients had no demonstrable neutralizing activity. Two plasma samples had neutralizing activity equivalent to that of normal plasma despite the lack of factor VIII clotting activity. Apparently, most patients with hemophilia A do not synthesize factor VIII, whereas a few synthesize an inactive molecule with a presumed genetic structural mutation of the active site but with antigenic determinants in common with normal factor VIII. Thus, hemophilia A is a disease caused by more than a single genetic mechanism.  相似文献   

5.
Dopamine synthesis: stimulation by a hypothalamic factor   总被引:2,自引:0,他引:2  
The effect of treatment with the factor that inhibits the release of melanocyte stimulating hormone (MSH) identified as 1-prolyl-1-leucylglycinamide (MIF) on brain catecholamine synthesis was examined in normal and hypophysectomized rats. The tripeptide induced a dose-related increase in striatal dopamine synthesis in slices obtained from treated normal animals but not in hypophysectomized animals. Hypothalamic norepinephrine synthesis was unaltered by MIF treatment in normal as well as in hypophysectomized rats. In addition, dopamine and norepinephrine syntheses were depressed in untreated hypophysectomized animals, as compared to normal controls. These results constitute the first direct demonstration of a central neurochemical effect of a hypothalamic factor.  相似文献   

6.
将一些统计量的不同估计利用加权平均构造一个新的估计法,能提高估计量的渐近效率。本文仅对服从正态分布的标准差利用这一新法,有效地改进了平均一阶连续差及平均二阶连续差的估计效率,前者的相对效率提高了28.45%,后者提高了41.85%。  相似文献   

7.
利用因子分析法对河南省各地市工业企业经济效益综合得分进行排序,从而得出各地市工业企业发展情况,结合各地特色,为各地市工业企业良性发展提供合理化指导。  相似文献   

8.
A portal blood factor as the humoral agent in liver regeneration   总被引:9,自引:0,他引:9  
It was demonstrated, by use of extracorporeal cross-circulation, that a humoral factor responsible for liver regeneration does not arise from the liver remnant. While intact livers of normal rats incorporated [methyl-(3)H]- thymidine in proportion to the amount of liver removed in the partner, the greatest response occurred after a total hepatectomy. Evidence from portacaval-shunted,partially hepatectomized animals connected to normal members indicates that the factor is in portal blood and that the onset of regeneration is the result of a quantitative imbalance between the available portal blood factor and the number of liver cells present.  相似文献   

9.
Overexpression of transforming growth factor alpha in psoriatic epidermis   总被引:40,自引:0,他引:40  
Transforming growth factor alpha (TGF-alpha) is produced by and required for the growth of epithelial cells and is angiogenic in vivo. Since epidermal hyperplasia and angiogenesis are hallmarks of psoriasis, TGF-alpha gene expression was analyzed in epidermal biopsies of normal and psoriatic skin. TGF-alpha messenger RNA and protein are much more abundant in lesional psoriatic epidermis than in normal-appearing skin of psoriatic patients or in normal epidermis. In contrast, messenger RNA levels of transforming growth factor beta 1 (TGF-beta 1), which inhibits epithelial cell growth, are not significantly different in normal, uninvolved, and lesional psoriatic epidermis. Thus, psoriatic epidermal hyperplasia may involve increased expression of a keratinocyte mitogen (TGF-alpha) rather than deficient expression of a growth inhibitor (TGF-beta 1).  相似文献   

10.
Because infant rats learn about odors that elicit suckling, and because certain chemosensory cues that help elicit mating behavior in adults are similar to those that elicit suckling, an experiment was undertaken to assess the influence of suckling-associated odors experienced during infancy on adult sexual behavior. Rat pups lived with and suckled dams whose nipple and vaginal odors were altered with citral, a lemon scent. The rats were weaned and never exposed again, until testing, to citral or females. At about 100 days of age, the males were paired in mating tests with a normal sexually receptive female or with a sexually receptive female that had been treated perivaginally with citral immediately before testing. The males ejaculated readily when paired with citral-treated females but were slow to achieve ejaculation when paired with normal females. These findings implicate an infantile experience as a determinant of adult sexual behavior in a mammal.  相似文献   

11.
Hageman factor: alterations in physical properties during activation   总被引:10,自引:0,他引:10  
Highly purified preparations of Hageman factor, a potent clotpromoting agent in normal mammalian plasma, had a sedimentation coefficient of approximately 5S before activation. After activation, the Hageman factor behaved as a much less soluble or larger molecule during ultracentrifugation and gel filtration. No significant change in sedimentation behavior was noted when the Hageman factor in plasma deficient in plasma thromboplastin antecedent was activated. The altered sedimentation behavior of purified activated Hageman factor probably reflects its decreased solubility in aqueous media.  相似文献   

12.
A tumor-derived growth factor that stimulates the proliferation of capillary endothelial cells has a very strong affinity for heparin. This heparin affinity makes it possible to purify the growth factor to a single-band preparation in a rapid two-step procedure. The purified growth factor is a cationic polypeptide, has a molecular weight of about 18,000, and stimulates capillary endothelial cell proliferation at a concentration of about 1 nanogram per milliliter.  相似文献   

13.
东风水库是玉溪市重要水源地,是生态建设和水源保护的重点区域。为探究该区域森林水源还养功能,选取枯落物最大持水率、蓄积量、有效拦蓄量以及土壤总孔隙度、非毛管孔隙度、土层厚度、土壤最大蓄水量为评价指标,构建森林水源涵养功能的综合评价方法,通过对东风水库流域范围内的5种主要森林类型的水源涵养功能进行综合评价。结果表明:5种主要森林类型的水源涵养功能都不是很好。水源涵养功能由大到小为板栗林、圣诞树林、冈栎林、混交林、杉木林。其中圣诞树林、冈栎林、板栗林的水源涵养功能较好,杉木林、混交林的水源涵养功能较差。  相似文献   

14.
A factor inhibitory to sodium transport exists in the sweat of patients with cystic fibrosis of the pancreas. When the duct system of the rat parotid was perfused with sweat from patients, marked inhibition of sodium reabsorption was observed. Perfusion with sweat from normal subjects caused no change in sodium reabsorption. The factor thus demonstrated may be responsible for the increased sodium concentrations in the sweat of patients with cystic fibrosis.  相似文献   

15.
Psychologists have repeatedly shown that a single statistical factor--often called "general intelligence"--emerges from the correlations among people's performance on a wide variety of cognitive tasks. But no one has systematically examined whether a similar kind of "collective intelligence" exists for groups of people. In two studies with 699 people, working in groups of two to five, we find converging evidence of a general collective intelligence factor that explains a group's performance on a wide variety of tasks. This "c factor" is not strongly correlated with the average or maximum individual intelligence of group members but is correlated with the average social sensitivity of group members, the equality in distribution of conversational turn-taking, and the proportion of females in the group.  相似文献   

16.
T-cell growth factor (TCGF) or interleukin-2 (IL-2), an immunoregulatory lymphokine, is produced by lectin- or antigen-activated mature T lymphocytes and in a constitutive manner by certain T-cell lymphoma cell lines. By means of a molecular clone of human TCGF and DNA extracted from a panel of somatic cell hybrids (rodent cells X normal human lymphocytes), the TCGF structural gene was identified on human chromosome 4. In situ hybridization of the TCGF clone to human chromosomes resulted in significant labeling of the midportion of the long arm of chromosome 4, indicating that the TCGF gene was located at band q26-28. Genomic DNA from a panel of hybrids prepared with HUT-102 B2 cells was examined with the same molecular clone. In this clone of cells, which produces human T-cell leukemia virus, the TCGF gene was also located on chromosome 4 and was apparently not rearranged. The homologous TCGF locus in the domestic cat was assigned to chromosome B1 by using a somatic cell hybrid panel that segregates cat chromosomes. Linkage studies as well as high-resolution G-trypsin banding indicate that this feline chromosome is partially homologous to human chromosome 4.  相似文献   

17.
在马尾松年生长周期中,定位逐月采样,比较解剖形成层活动的数量和产生木质部的结构与旬均温和旬雨量的关系.纺锤状原始细胞的分裂次数明显受温度控制,在月均温13.5~29.3℃的活动期中,以17.1~27.8℃分裂较快,并有一定抗旱性;在连续旬雨量10mm以下,仍能形成纺锤状细胞.管胞分化的下限温度约11℃,雨量是调节管胞腔径及壁、腔比值变化的主要因素.木射线细胞的生长受管胞结构的影响,其长和宽的扩大分别随管胞腔径和壁、腔比值提高而增加,在正常温度范围内,间隔性干旱有促进树脂道的形成.  相似文献   

18.
Wilcox RS 《Science (New York, N.Y.)》1979,206(4424):1325-1327
Even when blinded with masks, adult male water striders (Gerris remigis) accurately ascertain the sex of other adult water striders in the laboratory. Freely moving females that were artificially made to play back computer-generated male surface wave and body-contact signals of about 90 waves per second were treated as males by the masked males and as females when no such playbacks were made. Thus, the males can use presence or absence of the male signal as the sole means for sex discrimination.  相似文献   

19.
Total time required for larval and pupal development in Ephestia kühniella Z. was significantly modified when habitable space of the food mass was increased by dilution with a nontoxic sawdust. Doubling the living space resulted in an increased developmental rate, presumably due to a reduction in the number of larval interactions. Tripling the living space, however, produced a somewhat unexpected delay in development, accompanied by a marked increase in variance about the means for both males and females.  相似文献   

20.
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