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81.
Summary Prospective models are developed for analysing sperm competition data so as to predict the underlying mechanisms determining paternity in multiply mated females. The models require: 1) estimations of proportion of offspring sired by the last male to mate (P
2), 2) knowledge of the number of sperm transferred by each male, and 3) knowledge of the sperm storage capacity of the female, should this be limited. They will distinguish between raffles (sperm mixing without displacement) and sperm displacement mechanisms. The sensitivity of the techniques can be increased by manipulating the number of sperm transferred by each male. Typically, this can be done by manipulating copula duration or number of ejaculations, given a knowledge of the rate of sperm transfer. Data from two contrasting insect species are fitted to the models to demonstrate the techniques. These models are prospective only, and their limitations are discussed. The principal limitation is that we assume that sperm used for fertilization mix randomly in a fertilization set immediately prior to fertilization; in reality this may be difficult to identify. When sperm mixing is very rapid, the fertilization set will often be equivalent to the sperm stores, but with slow mixing, the fertilization set may be equivalent to a much more restricted zone and may change with time.
Offprint requests to: G.A. Parker 相似文献
82.
Simmons RW Noble AD Pongsakul P Sukreeyapongse O Chinabut N 《Environmental geochemistry and health》2009,31(1):71-79
Research undertaken over the last 40 years has identified the irrefutable relationship between the long-term consumption of
cadmium (Cd)-contaminated rice and human Cd disease. In order to protect public health and livelihood security, the ability
to accurately and rapidly determine spatial Cd contamination is of high priority. During 2001–2004, a General Linear Regression
Model Irr-Cad was developed to predict the spatial distribution of soil Cd in a Cd/Zn co-contaminated cascading irrigated
rice-based system in Mae Sot District, Tak Province, Thailand (Longitude E 98°59′–E 98°63′ and Latitude N 16°67′–16°66′).
The results indicate that Irr-Cad accounted for 98% of the variance in mean Field Order total soil Cd. Preliminary validation
indicated that Irr-Cad ‘predicted’ mean Field Order total soil Cd, was significantly (p < 0.001) correlated (R
2 = 0.92) with ‘observed’ mean Field Order total soil Cd values. Field Order is determined by a given field's proximity to
primary outlets from in-field irrigation channels and subsequent inter-field irrigation flows. This in turn determines Field
Order in Irrigation Sequence (Field OrderIS). Mean Field Order total soil Cd represents the mean total soil Cd (aqua regia-digested) for a given Field OrderIS. In 2004–2005, Irr-Cad was utilized to evaluate the spatial distribution of total soil Cd in a ‘high-risk’ area of Mae Sot
District. Secondary validation on six randomly selected field groups verified that Irr-Cad predicted mean Field Order total
soil Cd and was significantly (p < 0.001) correlated with the observed mean Field Order total soil Cd with R
2 values ranging from 0.89 to 0.97. The practical applicability of Irr-Cad is in its minimal input requirements, namely the
classification of fields in terms of Field OrderIS, strategic sampling of all primary fields and laboratory based determination of total soil Cd (T-CdP) and the use of a weighed coefficient for Cd (CoeffW). The use of primary fields as the basis for Irr-Cad is also an important practical consideration due to their inherent ease
of identification and vital role in the classification of fields in terms of Field OrderIS. The inclusion of mean field order soil pH (1:5water) to the Irr-Cad model accounted for over 79% of the variation in mean Field Order bio-available (DTPA (diethylenetriaminepentaacetic
acid)-extractable) soil Cd. Rice is the staple food of countries of the Greater Mekong Sub-region (includes Vietnam, Myanmar,
Lao PDR, Thailand and Yunnan Province, China). These countries also have actively and historically mined Zn, Pb, and Cu deposits
where Cd is likely to be a potential hazard if un-controlled discharge/runoff enters areas of rice cultivation. As such, it
is envisaged that the Irr-Cad model could be applied for Cd hazard assessment and effectively form the basis of intervention
options and policy decisions to protect public health, livelihoods, and export security. 相似文献
83.
Footprinting UK households: How big is your ecological garden? 总被引:1,自引:0,他引:1
84.
In the distributed signal detection theoretic (DSDT) model, the human operator and the warning mechanism are independent decision makers who work together as a team. The DSDT demonstrates that the optimal warning threshold, in general, differs from the signal detection theoretic (SDT) threshold, which assumes a single decision maker. This prediction was tested in an experiment where drivers received monetary rewards for making safe passing decisions on a driving simulator. The experiment focused on evaluating the quality of the decision making of the drivers, and not on perceptual issues. A collision avoidance system provided a warning when the probability of an inadequate overtaking gap exceeded a threshold. Three thresholds were tested. The control threshold resulted in no detections or false alarms. The DSDT threshold resulted in some misses but no false alarms. The SDT threshold resulted in no misses but frequent false alarms. As predicted, (1) drivers performed the best when the warning system used the DSDT threshold, and (2) use of the SDT threshold improved performance over the control threshold, even though four of the 10 drivers occasionally ignored the warning and made risky passing attempts in the SDT conditions, possibly because of earlier false alarms. These findings support the conclusion that the DSDT model is a useful, quantitative tool that should be used by warning designers. 相似文献