This article focuses on a few ecological and environmental problems that are occuring in the process of current urbanization,such as population growth,water shortage and environmental pollution, and evaluates the measures being taken for the protection of urban ecological environment.

Among the limited evaluation models, the one of sustainable degree lays stress on the key characteristic indices, and choos~the most critical one to construct model. It defines six factors to appraise the sustainable degree. That is economic development, development stage, energy consumption, population growth and environment quality.

The results indicated: returning cultivated land to woods and grasslands could not be accomplished, unless the rational food self-reliance percentage was determined through controlling population growth rigorously, and keeping stress of bearing capacity of population bellow zero or very little in short time.

The Cd2+ 、 Pb2+ 、 Cu2+ exhibited fairly strong inhibition to population growth of tetrahymena pyrifomis. They are the most sensitive to Cd2+ in their environment.

Study on Population Growth Processes and Interspecific Competition of Prorocentrum donghaiense and Skeletonema costatum in Semi-continuous Dilution Experiments

The influence of temperature and thermoperiod on the population growth of the leaf beetle Diorhabda rybakowi Weise was studied in the laboratory and life tables at temperatures from 19°to 35℃ and thermoperiods from 4° to 20℃ were constructed.

General situation of environtoxicological research with Tetrahymena pyriformiswas reviewed including population growth kinetics,morphology,structure,behavior and the characteristics of biophysiology and biochemistry.

The Difficulties and Puzzles in Estimation of Microbial Population Growth Parameters in Limiting Growth Environment by Logistic and Monod models

构建限制性条件下微生物群体生长模型时的问题

This paper discussed the difficulties and puzzles when describing microbial population growth characteristics in limiting environment by Logistic model and Monod model. Study discovered that Logistic model neglected two important biological parameters, namely generation time and lag phase.

A new class of competition models in which the population growth coefficients are represented by periodic delta-functions is designed.

Analysis of the available field and published data indicates a two-stage pattern of the population growth phase and a synchronous transition of wolf populations to this phase.

Selenium in concentrations of 0.01 and 0.5 mg/liter stimulated cell population growth, while the number of ultrastructural alterations was the same as in the control cells.

At a selenium concentrations of 1 mg/liter, cell population growth slightly decreased by the end of the experiment, and there was some increase in the number of cells with damaged organoids and in the number of completely destroyed cells.

salina, suppressing cell population growth and promoting extensive destructive changes.

The present paper proposes some aspects and procedures for establishing the long-term predictive equation of locust population fluctuations. Three kinds of predictive po-pulation models are introduced and discussed with respect to their practical value. Aseries of locust population data of 50 years, 1913--1962, taken from Hung-Tze Lake, a typical locust region, has been used to analyse the regularity of locust population dyna-mics, from which the effective factors have been selected to build up the predictivemodels....

The present paper proposes some aspects and procedures for establishing the long-term predictive equation of locust population fluctuations. Three kinds of predictive po-pulation models are introduced and discussed with respect to their practical value. Aseries of locust population data of 50 years, 1913--1962, taken from Hung-Tze Lake, a typical locust region, has been used to analyse the regularity of locust population dyna-mics, from which the effective factors have been selected to build up the predictivemodels. 1. Analysis of Outbreak Regularity 1) The running equation, E=(k--2npq)/(npq(1--3pq)~(1/2)) is employed to test the indepen-dence on outbreaks of one another. It is found that some connections are present be-tween two neighbouring outbreaks. This means that each outbreak would be consideredas a continuous part of the population fluctuation sequence which is influenced by theresultant effect of both locust bionomics and environmental factors. 2) Results obtained about the influence of climatic factors, by the analyticalmethods of contingence table and conditional probability, show that a dry climatic year ismore suitable to the locust population growth than wet years, and a dry summer is par-ticularly favorable as compared with spring. Such climatic condition may be expressed bythe climatic index shown as follows: Precipitation saturation deficit<3 andpopulation fluctuation or more useful for establishing thepredictive equations, such as the monthly mean temperature of January, lake water leveland the mortality of overwintering eggs for the summer generation, the flooding area oflower lands and lake water level for the fall generation. 3) In analyses made on periodicity of locust population dynamics, three periodicintervals are evident, and these are 2--3 years, 5--6 years and approximately 25 years.In addition, with the aid of the analysis of integral curve method, a periodicity of 25-year has also been revealed, and it is proved in accordance with the periodicity of drymonths from May to August. 4) The influence of crowding is another biological factor which has to be con-sidered in locust population fluctuation as exhibited by diminution of ovariole number andthe amount of eggs. The interrelationship between them has been calculated based on aseries experiments by using the transcendental equation which gives a well fit. 2. Prediction equations The predictive models are established by the following three methods: 1. By direct extrapolation method on the basis of 1) the analysis of population dynamics of the fluctuation form: First is to analysethe 50-year data by using the method of transition probability matrix of Markov Chain,then it gives two matrices in which we may find the higher transition probabilities oc-curing among the series of population abundances as follows: 2→3, 4→3, or 4→7,→8. 2) the characteristics of population fluctuation sequence: It is indicated that if thevalue of population abundance deviating from the mean level (y = 4.141) is plusor minus 2, the fluctuation tendency will reverse, for example, when x_ix_(i+1)>x_(i+2) then x_(i+3)>x_(i+2), generally x_(i+3)<4.1. 2. By the methods of random sequence and periodical equations based on environ-mental factors and population bionomics: the followng model is used y_t=f(t)+ξ(t)+g(t)(y(t)…predicted value of population abundance, f(t)…tendency factor, ξ(t)…random factor, g(t)…periodical factor) The estimation of these three factors dissolved are f~*(t)=4.475--0.0084t+0.38 sin (π/(12)t) ξ~*(t)=--0.1186ξ(t--1)--0.1452ξ(t--2) g~*(t)=g_7(t)+g_8(t)+…+g_(12)(t) 3. By stepwise multiple regression method: Equations are established based onnumerous variates, many of which have been sifted under given confidence levels (F=1.5,2.5) before they are taken in the predictive models. 1) Linear regression equa

Adults of Tetrastichus hagenowii and Tetrastichodes sp. emerged from the oothe-cae of Periplaneta fuliginosa collected from four places in Zunyi and the parasitism rates of the 'former species were 71.9%, 93.1%. 6.6% and O respectively. The sex ratio of the wasps emerged from fourteen oothecae was 1:0.4 in favous of the female. The maximum mumber of wasps emerged from a single ootheca was 202. Mating took place almost immediately after emergence of the wasps from the oothecae and egg laying soon fallwo-ed. They...

Adults of Tetrastichus hagenowii and Tetrastichodes sp. emerged from the oothe-cae of Periplaneta fuliginosa collected from four places in Zunyi and the parasitism rates of the 'former species were 71.9%, 93.1%. 6.6% and O respectively. The sex ratio of the wasps emerged from fourteen oothecae was 1:0.4 in favous of the female. The maximum mumber of wasps emerged from a single ootheca was 202. Mating took place almost immediately after emergence of the wasps from the oothecae and egg laying soon fallwo-ed. They were very active during the first 2 to 3 days.The wasps began to emerge in early April and the peak of population growth was from May to August. The life span of the females was from 3 to 47 days and that of the males from 2 to 40 days. Development of the immature stages ranged from 29 to 62 days in May and June, but might last 'for months in the winter. The oviposition period was rather long.Based on our results, we consider this species has potential value in biological control of the cockroach.

The inhibitory effect of selenium (as sodium selenite) on the population growth of Tetrahymena pyriformis S1 was investigated. Cells were grown either in inorganic salt medium with living Aerobacter aerogenes or yeast cells as particulate food or in liquid proteose peptone-yeast extract medium. The latter was found to be more adequate for the experiments. When the concentration of selenium in the medium was 1.4 ppm, inhibition of population growth began to appear and when it was raised to 140 ppm,...

The inhibitory effect of selenium (as sodium selenite) on the population growth of Tetrahymena pyriformis S1 was investigated. Cells were grown either in inorganic salt medium with living Aerobacter aerogenes or yeast cells as particulate food or in liquid proteose peptone-yeast extract medium. The latter was found to be more adequate for the experiments. When the concentration of selenium in the medium was 1.4 ppm, inhibition of population growth began to appear and when it was raised to 140 ppm, population growth stopped completely. The generation time prolonged with the increase of the selenium concentration. The entrance of selenium into the cells were evidenced by both radioactive 75Se tracer experiment and x-ray fluorescence analysis. Cells inhibited by selenite ion restored growth in the normal medium.