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251.
Self-organization theories and environmental management: The case of South Moresby,Canada 总被引:1,自引:0,他引:1
This article presents a new approach to the analysis and management of large-scale societal problems with complex ecological, economic, and social dimensions. The approach is based on the theory of self-organizing systems—complex, open, far-from-equilibrium systems with nonlinear dynamics. A brief overview and comparison of different self-organization theories (synergetics, self-organization theory, hypercycles, and autopoiesis) is presented in order to isolate the key characteristics of such systems.The approach is used to develop an analysis of the landuse controversy in the South Moresby area of the Queen Charlotte Islands, British Columbia, Canada. Critical variables are identified for each subsystem and classified by spatial and temporal scale, and discussed in terms of information content and internal/external origin. Eradication of sea otters, introduction of black-tailed deer, impacts of large-scale clearcut logging, sustainability of the coastal forest industry, and changing relations between native peoples and governments are discussed in detail to illustrate the system dynamics of the South Moresby sociobiophysical system. Finally, implications of the self-organizing sociobiophysical system view for regional analysis and management are identified. 相似文献
252.
253.
Dr. D. F. Callen G. Korban G. Dawson L. Gugasyan E. J. M. Krumins S. Eichenbaum J. Petrass S. Purvis-Smith A. Smith G. Den Dulk N. Martin 《黑龙江环境通报》1988,8(6):453-460
From a total of 1312 diagnostic chorionic villus samplings (CVS) there were 22 which showed discordance between the karyotype of the chorionic villi and that of the fetus. This frequency was some 20-fold higher than that reported at amniocentesis. In the majority of discordant cases, the fetal karyotype was normal while the placenta! karyotype was mosaic. In four cases, the placenta! karyotype was non-mosaic (a trisomy 16, a monosomy X, and two tetraploids) while the fetal karyotype was normal. In one case, the placenta was trisomy 18 while the fetus was mosaic. There were two ‘false-negative’ results where short-term methods showed only normal cells while both long-term cultures of chorionic villi and fetal cells were mosaic, in one 46,XY/47.XXY and in the other 46,X Y/47.X Y, + 21. 相似文献
254.
Kerry?L.?HowellEmail author Alex?D.?Rogers Paul?A.?Tyler David?S.?M.?Billett 《Marine Biology》2004,144(5):977-984
Zoroaster fulgens is a slope-dwelling seastar species that is distributed throughout the Atlantic Ocean. Studies into the population structure and systematics of marine animals have increasingly found that species with a reported cosmopolitan distribution are, in fact, collections of closely related cryptic or sibling species. In the Porcupine Seabight, three morphotypes of Z. fulgens can be found that have a distribution that is stratified by depth. This study investigates the genetic divergence between these morphotypes using sections of the cytochrome oxidase 1 (COI) and 16S regions of the mitochondrial genome. Bathymetrically separated morphotypes of Z. fulgens are reproductively isolated over distances of approximately 1 km while gene flow occurs among morphotypes, along isobaths, over distances of approximately 900 km. Reproductive isolation on the continental slope may have occurred as a result of selection exerted by gradients of depth-correlated physical factors, such as pressure and temperature. However, allopatric speciation with subsequent range expansion may also explain the observed patterns of genetic divergence. Further investigation of radiation within this group may provide important information on the evolution of slope species. Taxonomic revision of the genus is required.Communicated by J.P. Thorpe, Port Erin 相似文献
255.
Dr. R. L. Anderson M. S. Golbus C. J. R. Curry P. W. Callen W. H. Hastrup 《黑龙江环境通报》1990,10(8):513-518
Four cases of multiple gestation with second trimester death of one fetus and subsequent damage to a survivor are reported. Monochorionic placentation was documented in three of the cases. Central nervous system lesions occurred in all cases, and bowel injury was noted in two of the damaged fetuses. Although rare maternal clotting problems have been reported in similar situations, none was noted in any of these four cases. Prior reports have indicated that losses in the first half of gestation were of no consequence to the surviving fetuses. These four cases contradict this suggestion, and indicate that close sonographic observation of the survivors is important in any multiple gestation where one fetus has died. 相似文献
256.
Summary During their first 1–2 years of life, juvenile coho salmon (Oncorhynchus kisutch) are stream-dwelling, and feed upon drifting invertebrates. They move upstream from a holding position to intercept individual prey items; the distance moved (attack distance) is an increasing, but decelerating, function of prey size. Since the fish are presumably more visible to predators during such feeding excursions, prey size and risk are associated variables.The effect on attack distance of the presentation of a model predator (a photograph of a rainbow trout) was examined in the laboratory. Attack distances are shortened following presentation of a predator; this is particularly true when the prey are large (Fig. 1). The extent of the reduction of attack distance is directly related to predator presentation frequency, although there appears to be a minimum level to which it will decline (Fig. 2). Hungry fish and fish in the presence of a competitor (simulated by a mirror) are less responsive to the predator, suggesting a trade-off of energetic requirements and risk (Fig. 3 and Table 3). The effect of predation risk should be to reduce the relative proportion of large prey in a juvenile coho's diet, and its net rate of energy intake. 相似文献
257.
Summary The effect of kinship on incompatibility between colonies of the acacia-ant Pseudomyrmex ferruginea was examined. Colonies were reared on a clone of Acacia hindsii in a standard environment. A slight but significant reduction in intercolony incompatibility was obtained within two inbred lineages, compared with the observed frequency of rejection for unrelated colonies. These results indicate that the relevant odor differences between colonies are probably not determined at a single gene locus. The gestalt model for recognition pheromones does not apply to P. ferrugnea, since nestmates are often treated differently upon introduction to a second colony. However, the resulting intermediate rejection frequencies (30–100%) fail to converge on the 50% level predicted by single locus models for recognition pheromones. 相似文献
258.
Heikens A Widianarko B Dewi IC de Boer JL Seinen W van Leeuwen K 《Environmental geochemistry and health》2005,27(5-6):475-483
In Asembagus (East Java, Indonesia), surface water is contaminated with effluent from the hyperacid Ijen Crater Lake. In a
previous study, we reported that food crops irrigated with this water had increased concentrations of various elements. Here,
we present a total diet study for adults and 6-year-old children to determine if the mean daily intake of a broad range of
elements is safe and adequate. For children, the intake of B, Mg, Mn and V is high with Hazard Quotients (HQ) of 1.1 (B),
1.4 (Mn) and 1.4 (V), respectively (no TDI is available for Mg). For Mn, the daily intake is high due to the consumption of
locally produced rice. Drinking water is the main source of B, Mg and V. For adults, the intake of Mg, Mn and V is also high
but HQ values are ≤0.7. For both children and adults, the intake of Ca, Zn and particularly Fe is below the RNI (Fe intake
is 90% below the RNI for women). It is concluded the mean intake of elements is unbalanced and Fe deficiency is probably the
most serious health problem. Toxic effects cannot be fully excluded since deficiency of essential elements such as Ca, Fe
and Zn can increase the absorption and retention of various elements. 相似文献
259.