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611.
P. R. Teske F. R. G. Forget P. D. Cowley S. von der Heyden L. B. Beheregaray 《Marine Biology》2010,157(9):2029-2042
‘No-take’ marine protected areas (MPAs) are successful in protecting populations of many exploited fish species, but it is
often unclear whether networks of MPAs are adequately spaced to ensure connectivity among reserves, and whether there is spillover
into adjacent exploited areas. Such issues are particularly important in species with low dispersal potential, many of which
exist as genetically distinct regional stocks. The roman, Chrysoblephus laticeps, is an overexploited, commercially important sparid endemic to South Africa. Post-recruits display resident behavior and
occupy small home ranges, making C. laticeps a suitable model species to study genetic structure in marine teleosts with potentially low dispersal ability. We used multilocus
data from two types of highly variable genetic markers (mitochondrial DNA control region and seven microsatellite markers)
to clarify patterns of genetic connectivity and population structure in C. laticeps using samples from two MPAs and several moderately or severely exploited regions. Despite using analytical tools that are
sensitive to detect even subtle genetic structure, we found that this species exists as a single, well-mixed stock throughout
its core distribution. The high levels of connectivity identified among sites support the findings of previous studies that
have indicated that inshore MPAs are an adequate tool for managing overexploited temperate reef fishes. Even though dispersal
of adult C. laticeps out of MPAs is limited, the fact that the large adults in these reserves produce exponentially more offspring than their
smaller counterparts in exploited areas makes MPAs a rich source of recruits. We nonetheless caution against concluding that
the lack of structure identified in C. laticeps and several other southern African teleosts can be considered to be representative of marine teleosts in this region in general.
Many such species are represented in more than one marine biogeographic province and may be comprised of regionally adapted
stocks that require individual management. 相似文献
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After having been emitted at maximum rates in the 1960s and 1970s, lead has become less ubiquitous in industrialized countries as a result of increasingly stringent policies to limit the use of this heavy metal as an anti-knock additive in gasoline. Using a detailed reconstruction of lead emissions in Europe (PbE), of the air concentration of lead in Europe (PbC) and repeated measurements of lead concentrations in human blood (PbB) in Germany since about 1980, we have constructed an empirical model that estimates PbB given PbE. This model is used for 2 purposes: i)To estimate PbB levels for the 1960s and 1970s in Germany, when emissions were maximum and monitoring blood levels had not yet begun. It turns out that PbB peak emissions were reaching a mean level, which health officials considered potentially harmful for fetuses and small children. ii) To estimate how PbB levels may have developed if regulations of the use of lead in gasoline had been implemented differently. In case of no or delayed regulations, the model estimates that PbB levels well beyond the critical level would have emerged. Thus, the regulation instituted in Germany since the 1970s has reduced significant health hazards. 相似文献
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Deductive reasoning in pigeons 总被引:2,自引:0,他引:2
L. von Fersen C. D. L. Wynne J. D. Delius J. E. R. Staddon 《Die Naturwissenschaften》1990,77(11):548-549
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Summary Wheel-running activity was recorded in male golden hamsters (Mesocricetus auratus) that had been blinded by bilateral enucleation and then kept singly in cages in a continuously darkened cabinet (room 1). In an adjacent cabinet (room 2), sighted male and female hamsters were kept in a 12:12-h light-dark cycle. For time spans varying from 15 to 45 days, two females within their cages were transferred for 3 h each day from room 2 to room 1 at the same time of light-off in room 2. Afterwards, two sighted male hamsters were transferred to room 1 for 3 h each day for 28 days. For the last 70 days of the experiment, all blinded males were transferred permanently to room 2. There were three main results: (1) bilateral enucleation of the males in room 1 had no effect on phase or period of the free-running rhythm; (2) the rhythms of the blinded males were entrained neither by the 3-h daily presence of two females nor after the transfer into room 2; (3) the presence of females usually released activity in the males depending on the circadian phase at which the exposure to females occurred. The masking responses were maximal at the beginning of the activity time, and reached a minor second maximum approximately 9 to 12 h later. 相似文献
620.
Two experiments were carried out in order to investigate nicotine intake through passive smoking. In the first study, carboxyhemoglobin (COHb) and serum cotinine were found to increase to a similar extent in seven subjects breathing through the nose only and in another seven subjects breathing through the mouth only during exposure to environmental tobacco smoke. Similarly, no significant difference was found in urinary excretion of nicotine and cotinine over a period of 72 hours, although nicotine and cotinine excretion tended to be slightly higher after inhalation through the nose only. In the second study, nicotine was measured in four subjects who held mainstream or sidestream smoke in the mouth without inhaling. Cotinine levels in serum and amounts of nicotine and cotinine excreted in the urine were low compared with those measured in the breathing study. Nicotine from sidestream smoke, however, is more effectively absorbed by the oral mucosa than nicotine from mainstream smoke. The data suggest that nicotine intake from passive smoking largely takes place in the bronchial tree and that nicotine absorption via the nasal or the oral mucosa is only of minor significance. 相似文献