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1.
L A Grigor'eva 《Parazitologiia》1992,26(5):430-435
In order to estimate the absolute number of Stomoxys calcitrans subpopulation in housings of a dairy farm the capture-mark-recapture method has been used. It has been established that the absolute number of S. calcitrans subpopulation can be as high as 100,000 specimens per a farmyard. The possibilities of using indices of the relative number of flies (caught on fly-paper) for estimation of the absolute number of these insects in the housings of farms have been found out. 相似文献
2.
Combinatory mathematical model of equilibrium binding of recognising proteins to DNA has been considered. The expression for the ratio of specific and unspecific complex as the function of a number of nucleotides in DNA, a number of centers of recognition, concentration of recognising molecules and a code number have been obtained. The analysis of obtained expression for the repressor--operator system showed that binary code would preferable than quartic one. The specificity of binding corresponding to experimental results have been observed by the number of centers more than twenty, in the narrow interval of the energy value and by high limitation on the number of combinations of error centers. 相似文献
3.
R I Valitskaia G S Shishkin T V Voevoda 《Biulleten' eksperimental'no? biologii i meditsiny》1988,106(7):122-124
The structure of the bronchial tree in the lung lobules has been studied and the number of lobules and acini in different lobes and in the entire lung has been determined in polar foxes and dogs. Branching pattern and the number of generations of interlobular and intralobular bronchioli have been defined. It has been found that the number of lung lobules in polar foxes was twice as high as in dogs, the lobule volume being smaller almost by half. A smaller number of acini in polar fox lobules enables the central regulation mechanisms to intensify the control of local ventilation. It broadens the possibilities for physiological responses to the influence of climatic factors of the Extreme North. 相似文献
4.
Derivation of unstirred-layer transport number equations from the Nernst-Planck flux equations.
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P H Barry 《Biophysical journal》1998,74(6):2903-2905
Since the late 1960s it has been known that the passage of current across a membrane can give rise to local changes in salt concentration in unstirred layers or regions adjacent to that membrane, which in turn give rise to the development of slow transient diffusion potentials and osmotic flows across those membranes. These effects have been successfully explained in terms of transport number discontinuities at the membrane-solution interface, the transport number of an ion reflecting the proportion of current carried by that ion. Using the standard definitions for transport numbers and the regular diffusion equations, these polarization or transport number effects have been analyzed and modeled in a number of papers. Recently, the validity of these equations has been questioned. This paper has demonstrated that, by going back to the Nernst-Planck flux equations, exactly the same resultant equations can be derived and therefore that the equations derived directly from the transport number definitions and standard diffusion equations are indeed valid. 相似文献
5.
Jaglarz M 《Tissue & cell》1992,24(3):397-409
The ovaries of 31 species of the coleopteran familyCarabidae have been studied by light and electron microscopy. Ovarioles of all the examined insects are of the polytrophic type. In the majority of the species a constant number of nurse cells per egg chamber has been observed. However, several species do not obey the 2(n) rule and the number of nurse cells varies considerably even in the consecutive egg chambers of the same ovariole. In spite of the differences, the number of intercellular bridges connecting nurse cells to the oocyte is fixed and species specific. InCarabidae seven types of egg chambers have been characterized regarding the number of divisions, the number of nurse cells and the way the nurse cells are bridged to the oocyte. Some phylogenetic implications are considered. 相似文献
6.
Eric H. Roalson 《The Botanical review》2008,74(2):209-393
The Cyperaceae are well known for having a large amount of variation in chromosome numbers both within and among genera. Most
of this variation has been previously attributed to agmatoploid or qualitative aneuploid chromosome number change. To date
there have been 4,231 reported chromosome number counts in the family. Despite the large number of counts made, they only
represent approximately 16% of the species currently recognized. These counts are here presented in an indexed list with standardized
nomenclature following a draft copy of the World Checklist of Cyperaceae. Additionally, I explore variation within genera
where a significant number of counts have been made. Given the distributions of counts within genera there is evidence for
both agmatoploid and polyploid chromosome number changes. 相似文献
7.
M Radkowski T Laskus E Kopicz-Kamińska L Babiuch J Slusarczyk 《Polski tygodnik lekarski (Warsaw, Poland : 1960)》1992,47(36-37):787-789
Lymphocytes CD8+ have been assayed prospectively in 245 individuals infected with HIV. Percentage and number of CD8+ have been nearly two-fold higher in asymptomatic patients or patients with lymphadenopathy than those in the control group. The number of CD8+ lymphocytes has been rapidly decreasing parallel to the progression of HIV (ARC and AIDS), while their percentage has increased--however insignificantly. There has been a positive correlation between the number of CD4+ and CD8+ cells and all clinical stages of HIV infection. 相似文献
8.
The parameters affecting the separation and quantification of triglycerides by gas-liquid chromatography have been investigated with the use of QF-1 and SE-30 as stationary phases and a flame ionization detector. The isothermal characteristics of a wide variety of triglycerides (carbon number 6 to 60) on both columns show that long retention volume is directly proportional to carbon number and inversely proportional to absolute temperature. Isothermal retention indices of some triglycerides are given, as are column efficiencies (in terms of theoretical plates and ability to separate closely related triglycerides). When various rates of programmed temperature rise are used, retention indices have been found to be less useful than absolute or relative elution temperatures. The elution temperatures of triglycerides of carbon number 6 to 54 have been determined relative to that of trilaurin. Under optimal separation conditions weight and molar correction factors can be obtained. Triolein and tristearin have been partially separated, as have certain triglycerides that have the same carbon number but widely different fatty acids. The natural triglycerides of human milk fat have been separated. 相似文献
9.
? Estimation of the proportion of undescribed fungal taxa is an issue that has remained unresolved for many decades. Several very different estimates have been published, and the relative contributions of traditional taxonomic and next-generation sequencing (NGS) techniques to species discovery have also been called into question recently. ? Here, we addressed the question of what proportion of hitherto unidentifiable molecular operational taxonomic units (MOTUs) have already been described but not sequenced, and how many of them represent truly undescribed lineages. We accomplished this by modeling the effects of increasing type strain sequencing effort on the number of identifiable MOTUs of the widespread soil fungus Mortierella. ? We found a nearly linear relationship between the number of type strains sequenced and the number of identifiable MOTUs. Using this relationship, we made predictions about the total number of Mortierella species and found that it was very close to the number of described species in Mortierella. ? These results suggest that the unusually high number of unidentifiable MOTUs in environmental sequencing projects can be, at least in some fungal groups, ascribed to a lag in type strain and specimen sequencing rather than to a high number of undescribed species. 相似文献
10.
W.Curtis Johnson 《Carbohydrate research》1977,58(1):9-20
Fragment spectra are presented that may be summed algebraically to predict the vacuum-ultraviolet, circular-dichroism spectra of certain pyranoid monosaccharides. It is shown that a limited number of these fragment spectra can be used to calculate a larger number of circular-dichroism spectra that had been measured previously. Furthermore, the circular-dichroism spectra of a number of other monosaccharides, whose spectra have not yet been measured, can be predicted. 相似文献
11.
Shixiang Wang Huimin Li Minfang Song Ziyu Tao Tao Wu Zaoke He Xiangyu Zhao Kai Wu Xue-Song Liu 《PLoS genetics》2021,17(5)
Genome alteration signatures reflect recurring patterns caused by distinct endogenous or exogenous mutational events during the evolution of cancer. Signatures of single base substitution (SBS) have been extensively studied in different types of cancer. Copy number alterations are important drivers for the progression of multiple cancer. However, practical tools for studying the signatures of copy number alterations are still lacking. Here, a user-friendly open source bioinformatics tool “sigminer” has been constructed for copy number signature extraction, analysis and visualization. This tool has been applied in prostate cancer (PC), which is particularly driven by complex genome alterations. Five copy number signatures are identified from human PC genome with this tool. The underlying mutational processes for each copy number signature have been illustrated. Sample clustering based on copy number signature exposure reveals considerable heterogeneity of PC, and copy number signatures show improved PC clinical outcome association when compared with SBS signatures. This copy number signature analysis in PC provides distinct insight into the etiology of PC, and potential biomarkers for PC stratification and prognosis. 相似文献
12.
PGF2alpha and PGE2 have been instilled in small amounts (5mug) into the uterine horns of pregnant rats at different intervals following mating. Unilateral as well as bilateral injections have been used. Three parameters have been taken into consideration at laparotomy performed on the 13th day of pregnancy: a) the number of implantation sites; b) the number of viable fetuses; and c) the number of corpora lutea present on the ovarian surface. Both PGs proved able to inhibit implantation, to affect the development of embryos and to exert some luteolytic activity when given between D-1 and D-6 of pregnancy. 相似文献
13.
The genetic control of the traits "plant height", "the number of lateral shoots" and "the number of lateral stems" has been studied in 3 pure lines and 1 variety of linseed according to the model 1 of Hayman method. It has been shown that the traits under investigation are inherited according to the additive-dominant model of genetic control in the absence of any interloci interactions. The higher plant height and numerous lateral shoots are recessive traits controlled by 2 blocks of polymeric genes, whereas the trait of numerous lateral stems is a dominant trait influenced by 1 to 3 blocks of genes. The linseed lines have been ranked according to the number of dominant alleles they have. Suggestions for selection using these parental genotypes have been made. 相似文献
14.
L A Piruzian E M Mikha?lovski? V A Dement'ev 《Izvestiia Akademii nauk SSSR. Seriia biologicheskaia》1989,(6):838-842
On the basis of analysis of a number of documents concerning the molecular mechanisms of actions of well-known drugs the first attempt has been made to subdivide their activities into traditional and nontraditional ones. The possibility of application of a number of well-known drugs to nontraditional fields of pharmacology has been demonstrated. 相似文献
15.
A A Zamiatnin 《Zhurnal obshche? biologii》1990,51(2):147-162
A number of problems connected with the study of several hundreds of known endogenous peptide molecules have been considered on the basis of data obtained from EROP-Moscow database. A large number of peptide structures can be reduced to a relatively small number of peptide families formed on the basis of homology of amino acid sequence. The ability of most peptides to participate in different regulatory systems of an organism has been demonstrated and the physical and chemical basis for specificity and ambiguity has been discussed. Most problems of structure, function, and localization of endogenous regulatory peptides are similar both in higher and in lower organisms. 相似文献
16.
Z Janczewski L Bablok S Fracki A Smith 《Polski tygodnik lekarski (Warsaw, Poland : 1960)》1992,47(24-26):530-532
A structure of the convoluted tubuli, spermatogenesis and number of Leydig's cells in the andropause have been analysed in dependence on the degree of symptoms intensity. A control group included otherwise healthy men with ++post-inflammatory azoospermia. A percentage of the convoluted tubuli with normal tissue (p < .002) and spermatogenesis (p < .001) has been significantly decreased in andropause. The number of Leydig's cells has not differed in andropause and in a control group (p < .05). No difference of significance have been noted in the structure of convoluted tubuli, spermatogenesis, and Leydig's cells number depending on the intensity of symptoms. FSH and LH levels have been significantly increased in andropause (p < .001). No relationship between FSH and LH levels and percentage of the abnormal convoluted tubuli has been observed. However there have been a relationship between FSH and LH levels and the number of abnormal convoluted tubuli with spermatogenesis inhibition and intensified clinical symptoms. There has also been a relationship between FSH and LH levels and Leydig's cells number in patients with marked symptoms of andropause. 相似文献
17.
Thomas K. Bauer Stefan Bender Jörg Heining Christoph M. Schmidt 《Economics & Human Biology》2013,11(4):545-550
Based on multivariate linear regression models, we analyze the effect of the lunar cycle and the number of sunspots occurring on a particular day on the number of births using social security data and controlling for a number of other potential confounders. The daily numbers of births between 1920 and 1989 have been calculated from the full sample of individuals who have been registered at least once in the German social security system. While the lunar cycle does not affect the number of births, the number of sunspots is positively correlated to the number of births. The empirical results may be explained by medical technological progress making natural influences on births less important over time. This interpretation is supported by the results on the intertemporal influence of weekends and holidays on the frequency of daily births. 相似文献
18.
Site-directed mutagenesis reveals the importance of conserved charged residues for the transport activity of the PheP permease of Escherichia coli. 总被引:2,自引:2,他引:0
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Site-directed mutagenesis has been used to identify a number of charged residues essential for the transport activity of the PheP protein. These residues are highly conserved in the cluster of amino acid transporters. However, some other conserved residues and a number of aromatic residues have been shown not to be essential for transport activity. 相似文献
19.
PGF2 and PGE2 have been instilled in small amounts (5 μg) into the uterine horns of pregnant rats at different intervals following mating. Unilateral as well as bilateral injections have been used. Three parameters have been taken into consideration at laparotomy performed on the 13th day of pregnancy: a) the number of implantation sites; b) the number of viable fetuses; and c) the number of corpora lutea present on the ovarian surface. Both PGs proved able to inhibit implantation, to affect the development of embryos and to exert some luteolytic activity when given between D-1 and D-6 of pregnancy. 相似文献
20.
Mikhalevskaia OB 《Ontogenez》2002,33(4):258-263
Length of elementary shoot is and the number of metamers in them have been compared in a number of ligneous plants. The shoot length varies to greater extent as compared to the number of metamers. The number of metamers with bud scales is the most constant and species-specific. This indicates relative independence of the intrabud stage of the shoot development. 相似文献