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591.
Steven M. Lipson Fatma S. Ozen Laina Karthikeyan Ronald E. Gordon 《Food and environmental virology》2012,4(4):168-178
Cranberry (Vaccinium macrocarpon) and grape (Vitis labrusca) juices, and these species?? secondary plant metabolites [i.e., proanthocyanidins (PACs)] possess antiviral activity. An understanding of the mechanism(s) responsible for these juices and their polyphenolic constituents?? direct effect on enteric virus integrity, however, remains poorly defined. Using the rotavirus (RTV) as a model enteric virus system, the direct effect of manufacturer-supplied and commercially purchased juices [Ocean Spray Pure Cranberry 100?% Unsweetened Juice (CJ), Welch??s 100?% Grape Juice (GJ), 100?% Concord (PG) and 100?% Niagara juices (NG)] and these species?? cranberry (C-PACs) and grape PACs (G-PACs) was investigated. Loss of viral capsid integrity in cell-free suspension by juices and their PACs, and as a factor of pH, was identified by an antigen (RTV) capture enzyme-linked immunosorbent assay. At native and an artificially increased suspension at or near pH 7, loss of viral infectivity occurred after 5?min, in the order CJ?>?NG?=?GJ?>?PG, and PG?>?GJ?=?NG?=?CJ, respectively. Antiviral activity of CJ was inversely related to pH. Grape, but not cranberry PACs, displayed a comparatively greater anti-RTV activity at a suspension pH of 6.7. Anti-RTV activity of C-PACs was regained upon reduction of RTV-cranberry PAC suspensions to pH 4. An alteration or modification of Type A PAC (of V. macrocarpon) structural integrity at or near physiologic pH is suggested to have impacted on this molecule??s antivirus activity. Type B PACs (of V. labrusca) were refractive to alternations of pH. Significantly, findings from pure system RTV?CPAC testing paralleled and in turn, supported those RTV-juice antiviral studies. Electron microscopy showed an enshroudment by PACs of RTV particles, suggesting a blockage of viral antigenic binding determinants. The implications of our work are significant, especially in the interpretation of PAC (and PAC-containing food)?CRTV interactions in the differing [pH] conditions of the gastrointestinal tract. 相似文献
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David D. Hope David B. Lank Ronald C. Ydenberg 《Behavioral ecology and sociobiology》2014,68(5):827-838
Ecological theory for long-distance avian migration considers time-, energy-, and mortality-minimizing tactics, but predictions about the latter have proven elusive. Migrants must make behavioral decisions that can favor either migratory speed or safety from predators, but often not both. We compare the behavior of adult and juvenile western sandpipers Calidris mauri during the course of their temporally segregated passages at a major stopover site. Here, the passage and winter arrival of an important predator, the peregrine falcon Falco peregrinus begins near the end of the adult sandpiper passage (July) and increases rapidly through the juvenile passage (August). The mortality-minimizing hypothesis predicts that as the falcon front is distant but approaching, sandpipers should initially increase the fuel-loading rate (lowered vigilance and predator apprehension) to increase migration speed and so maintain their head start. As the falcon front gains proximity to and passes over the stopover site, sandpipers should become increasingly cautious. Our measurements show that adults decreased vigilance during the period prior to falcon arrival, and had lower vigilance overall than juveniles. Juveniles were more apprehensive, flying further and longer in response to disturbance by a falcon silhouette. This trend was reversed in response to a human approach. Both groups were more vigilant and more apprehensive in a study year with earlier falcon arrival. These results suggest that late (juvenile) and early (adult) migrants minimize mortality on migration in different ways, adults by increased migratory speed at the expense of caution on stopover sites, and juveniles by increased caution at the expense of speed. 相似文献
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595.
Yonggang?Nie Ronald?R.?Swaisgood Zejun?Zhang Xiaobin?Liu Fuwen?WeiEmail author 《Behavioral ecology and sociobiology》2012,66(5):721-730
The giant panda (Ailuropoda melanoleuca) is notoriously difficult to study in the wild, but its interesting reproductive ecology makes the effort worthwhile. Perhaps
more than most species, the panda is energy-limited, which alters the cost/benefit analysis of its reproductive ecology. Using
global positioning system/very high frequency radiocollars to locate mating aggregations, we used behavioral observations
and fecal testosterone assays to gain insight into male panda reproductive effort and strategies, and test theories relating
to reproductive competition. Male pandas initially competed fiercely for access to females that were about to be fertile,
but once male competitive status was determined, aggression rates declined. Contact aggression was only observed during the
first 2 days of mating aggregations; thereafter, it was replaced with noncontact aggression and avoidance. Agonistic interactions
were highly asymmetrical, with contest losers (subordinates) showing less aggression and more avoidance than contest winners
(dominants), both before and after contest outcome was established. The competitively superior male displayed mate-guarding
tactics and secured all observed copulations. Contrary to theoretical predictions, testosterone levels did not predict aggression
levels or contest winners and also were not affected by winning or losing a contest. Body size appeared to be the primary
determinant of contest outcome. We discuss our findings in light of theoretical predictions, such as those arising from the
“challenge hypothesis,” in the context of the giant panda’s foraging and nutritional ecology. 相似文献
596.
Simulation of information propagation in real-life primate networks: longevity, fecundity, fidelity 总被引:1,自引:1,他引:0
In many vertebrate species, we find temporally stable traditions of socially learned behaviors. The social structure of animal
populations is highly diverse and it has been proposed that differences in the social organization influence the patterns
of information propagation. Here, we provide results of a simulation study of information propagation on real-life social
networks of 70 primate groups comprising 30 different species. We found that models that include the social structure of a
group differ significantly from those that assume random associations of individuals. Information spreads slower in the structured
groups than in the well-mixed groups. While we found only a minor effect on the path lengths of the transmission chains, robustness
against information extinction was strongly influenced by the group structure. Interestingly, robustness against information
loss was not correlated with propagation speed but could be predicted reasonably well by relative strength assortativity—a
structural network metric. In those groups where highly pro-social individuals preferentially interact with other pro-social
individuals, information was more likely to be lost. Our results show that incorporating group structure in any social propagation
model significantly alters predictions for spreading patterns, speed, and robustness of information. 相似文献
597.
Characterizing the Florida Keys National Marine Sanctuary (FKNMS), USA, has gained much attention over the past several decades
because of apparent changes in the benthic community structure over space and time representative of patterns occurring in
the Caribbean region. We used a 5-year dataset (1996–2000) of macroalgal and sponge cover and water quality measurements as
predictor variables of hard coral community structure in the FKNMS. The 16 water quality variables were summarized into 4
groups by principal component analysis (PCA). Hierarchical agglomerative cluster analysis of the mean and standard deviation
(SD) of the principal component scores of water quality variables separated the reef sites into two main groups (and five
sub-groups), referred to as reefs of similar influence (RSI). The main groups corresponded with their geographical locations
within the Florida Keys: the reefs in the Upper and Middle Keys being homogeneous and collectively, having lower water quality
scores relative to reefs in the Lower Keys. Canonical correspondence analysis (CCA) between hard coral cover and key predictor
variables (i.e., water quality, macroalgal cover and sponge cover) also separated the reefs in the Lower Keys from reefs in
the Upper–Middle Keys, consistent with results of the cluster analysis, which categorized reefs based on RSI. These results
suggest that the prevailing gradient of predictor variables may have influenced the structuring of coral reef communities
at a spatial scale larger than the individual reef. Furthermore, it is conceivable that these predictor variables exerted
influence for a long time rather than being a recent event. Results also revealed a pattern showing reduction in hard coral
cover and species richness, and subsequent proliferation of macroalgae and sponges during the study period. Our analyses of
the Florida Keys present a pattern that is consistent with the characteristics of a reef that has undergone a “phase-shift,”
a phenomenon that is widely reported in the Caribbean region. 相似文献
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600.
Determining the appropriate criteria and designs for hazardous waste landfill covers has spawned much discussion within the environmental remediation arena. Very little reliable comparison of various technologies exists. Researchers at Los Alamos National Laboratory studied the relative hydrologic performance of four landfill cover designs—two capillary barrier designs, one modified EPA RCRA design, and one control cover. Monitoring the fate of natural precipitation for nearly four years showed that the covers with barrier layers more effectively reduced deep percolation than the control cover. Although none entirely eliminated deep percolation, the RCRA cover, incorporating a clay hydraulic barrier, most effectively controlled it. The two capillary barriers reduced deep percolation, but significant amounts were still produced. Over 90 percent of all percolation through the covers, and lateral flow within the covers, occurred during February through May each year, primarily as a result of snowmelt, early spring rains, and low evapotranspiration. The study also showed that gravel mulch surface treatments (70- to 80-percent ground cover) reduced runoff and erosion. Despite additional shrubs planted on one, the two plots receiving the gravel mulch treatments exhibited equally enhanced amounts of evapotranspiration. 相似文献