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991.
Egyptian coastlines comprise more than 3000 km along the Mediterranean and the Red Sea. The coastal area of Egypt is under
severe and increasing pressure. After passing the law on the Environment (Law 4) in 1994, the Egyptian Environmental Affairs
Agency (EEAA) was designated as the responsible agency to implement this law. In this respect, the EEAA formulates the general
policy and prepares the necessary plans for the protection and promotion of the environment. Also, it follows up the implementation
of such plans in coordination with competent administrative authorities. Integrated Coastal Zone Management (ICZM) is one
of the items regulated and addressed by Law 4/94. A framework programme for ICZM in Egypt was issued in 1996. This paper presents
the results of a pilot project financed by the Mediterranean Action Programme Coastal Area Management (CAMP), namely ‘Fuka-Matrouh-Egypt’
project, and implemented by the Priority Action Plan/Regional Activity Centre. It also presents the methodology followed in
the study and the experience gained nationally that would lead to the sustainable development of the northwest Egyptian Coast. 相似文献
992.
Using Age Structure to Detect Impacts on Threatened Populations: a Case Study with Steller Sea Lions 总被引:3,自引:0,他引:3
Abstract: A delayed response to change is often a characteristic of long-lived species and presents a major challenge to monitoring their status. However, rapid shifts in age structure can occur even while population size remains relatively static. We used time-varying matrix models to study age-structure information as a tool for improving detection of survivorship and fecundity change and status. We applied the methods to Steller sea lions ( Eumetopias jubatus ), a long-lived endangered marine mammal found throughout the North Pacific Rim. Population and newborn counts were supplemented with information on the fraction of the population that was juvenile, obtained by measuring animals in aerial photographs taken during range-wide censuses. By fitting the model to 1976–1998 data, we obtained maximum-likelihood estimates and 95% confidence intervals for juvenile survivorship, adult survivorship, and adult fecundity in the mid-1980s, late 1980s, and 1990s. We used a series of nested models to test whether the data were best fit by a model with one, two, or three temporal changes in demographic rates, and we fit the models to different lengths of data to test the number of years of data needed to detect a demographic change. The declines in the early 1980s were associated with severely low juvenile survivorship, whereas declines in the 1990s were associated with disproportionately low fecundity. We repeated these analyses, fitting only to the count data without the juvenile-fraction information, to determine whether the age-structure information changed the conclusions and/or changed the certainty and speed with which demographic-rate changes could be detected. The juvenile-fraction data substantially improved the degree to which estimates from the model were consistent with field data and significantly improved the speed and certainty with which changes in demographic rates were detected. 相似文献
993.
Designing Effective Marine Protected Areas in Seaflower Biosphere Reserve, Colombia, Based on Biological and Sociological Information 总被引:3,自引:0,他引:3
A. FRIEDLANDER† J. SLADEK NOWLIS‡§ J. A. SANCHEZ†† R. APPELDOORN‡‡ P. USSEGLIO§§ C. McCORMICK §§ S. BEJARANO††† A. MITCHELL-CHUI§§ 《Conservation biology》2003,17(6):1769-1784
Abstract: Ecologists have paid increasing attention to the design of marine protected areas (MPAs), and their design advice consistently recommends representing all habitat types within MPAs or MPA networks as a means to provide protection to all parts of the natural ocean system. Recent developments of new habitat-mapping techniques make this advice more achievable, but the success of such an approach depends largely on our ability to define habitat types in a way that is ecologically relevant. We devised and tested the ecological relevance of a set of habitat-type definitions through our participation in a stakeholder-driven process to design a network of MPAs, focusing on no-take marine reserves in the Seaflower Biosphere Reserve, San Andrés Archipelago, Colombia. A priori definitions of habitat types were ecologically relevant, in that our habitat-type definitions corresponded to identifiable and unique characteristics in the ecological communities found there. The identification of ecological pathways and connectivity among habitats also helped in designing ecologically relevant reserve boundaries. Our findings contributed to the overall design process, along with our summary of other general principles of marine reserve design. Extensive stakeholder input provided information concerning the resources and their patterns of use. These inputs also contributed to the reserve design process. We anticipate success for the Seaflower Biosphere Reserve at achieving conservation and social goals because its zoning process includes detailed yet flexible scientific advice and the participation of stakeholders at every step . 相似文献
994.
The lead isotopic composition of various sections (crown, crown base, root) of teeth was determined in specimens collected from 19th century skulls preserved in museum collections and, upon extraction or exfoliation, from humans of known ages residing in Scotland in the 1990s. For most 20th century samples, calculation of accurate crown-complete or root-complete dates of tooth formation ranging from the 1920s to the 1990s enabled comparison of 206Pb/207Pb ratios for teeth sections (crown base root) with corresponding decadally averaged data for archival herbarium Sphagnum moss samples. This showed that the teeth sections had been significantly influenced by incorporation of non-contemporaneous (more recent) lead subsequent to the time of tooth formation, most probably via continuous uptake by dentine. This finding confirmed that separation of enamel from dentine is necessary for the potential of teeth sections as historical biomonitors of environmental (and dietary) lead exposure at the time of tooth formation to be realised. Nevertheless, the mean 19th century value of 1.172±0.007 for the 206Pb/207Pb ratio in teeth was very similar to the corresponding mean value of 1.173±0.004 for 19th century archival moss, although relative contributions from environmental sources – whether direct, by inhalation/ingestion of dust contaminated by local lead smelting (206Pb/207Pb~1.17) and coal combustion (206Pb/207Pb~1.18) emissions, or indirect, through ingestion of similarly contaminated food – and drinking/cooking water contaminated by lead pipes of local origin, cannot readily be determined. In the 20th century, however, the much lower values of the 206Pb/207Pb ratio (range 1.100–1.166, mean 1.126±0.013, median 1.124) for the teeth collected from various age groups in the 1990s reflect the significant influence of imported Australian lead of lower 206Pb/207Pb ratio (~1.04) and released to the environment most notably through car-exhaust emissions arising from the use of alkyl lead additives (206Pb/207Pb~1.06–1.09) in petrol in the U.K. from ca. 1930 until the end of the 20th century. 相似文献
995.
Dissolved Organic Matter in Forest Soils: Sources, Complexing Properties and Action On Herbaceous Plants 总被引:2,自引:0,他引:2
A. T. Kuiters 《Chemistry and Ecology》1993,8(3):171-184
Dissolved organic matter (DOM) is an important component of plant-soil systems. Its essential role in soil solution chemistry, soil-forming processes and its effects on biota, including soil fauna, bacteria, fungi and plants, is extensively documented in literature. in this contribution several forest leaf litter types are compared as sources of DOM and the released organics are subjected to gel permeation chromatography to reveal their molecular-size distribution. Moreover, complexing properties, as an indication for the podzolization potential of the litter leachates, were established. the occurrence and properties of DOM in different soil horizons were monitored beneath a stand of Scots pine. the effects of the different groups of soluble organics including phenolic, fulvic and humic acids, and of water-extractable humic substances on the performance of herbaceous plants of the forest floor are briefly reviewed. 相似文献
996.
The larval development of Clibanarius albidigitus Nobili is described and illustrated from laboratory-reared specimens. At 30°C, this species passes through four zoeal stages before molting to the megalopa. Of the 120 individual larvae reared, survival was high, with 88% reaching the megalopal stage. Zoeal stage durations varied from 3 to 18 d. Rearing was terminated after 45 d, and at that time no megalopae had molted to the firstcrab stage. Among known larvae of Clibanarius species, C. albidigitus is immediately distinguished by the presence of dorsomedial and dorsolateral carapace keels. 相似文献
997.
Phaeocystis blooms and eutrophication of the continental coastal zones of the North Sea 总被引:7,自引:0,他引:7
It is suggested that novel nuisance algal blooms can result from major shifts in N/P or NH4
+/NO3
- ratios. Inland hydraulic engineering caused a shift from P-limitation (before 1977) towards N-limitation (after 1977) in the Marsdiep area (Dutch coastal waters). Following this shift the colonial flagellate Phaeocystis sp. became more abundant and started to bloom during the nutrient-controlled period (later spring to autumn). Competition experiments showed that the N/P ratio can influence the species composition of marine phytoplankton. In addition, the natural distribution of some species like Rhodomonas sp. and Emiliania huxleyi may be affected by the frequency of nutrient pulses in the system. Phaeocystis was a poor competitor under P-limitation and a good competitor under N-limitation. Colony formation was absent under P- and NH4
+-limitation. Colonies were formed under NO3
--limitation. These preliminary results suggest that colony-forming Phaeocystic blooms may be restricted (besides light-controlled environments) to those N-controlled environments where nitrate is consumed by Phaeocystis. The distribution of Phaeocystis along the European continental coast is evaluated on the basis of its ability to compete for nutrients and to form colonies when nitrate is the major N-source. 相似文献
998.
The high frequency of extra-pair paternity in tree swallows is not an artifact of nestboxes 总被引:6,自引:0,他引:6
C. A. Barber Raleigh J. Robertson Peter T. Boag 《Behavioral ecology and sociobiology》1996,38(6):425-430
A common criticism of nestbox studies is one of creating artificial nesting conditions and breeding behavior different from
what would be seen under natural conditions. We assessed the frequency of extra-pair paternity (percentage of broods with
at least one extra-pair young) in 25 families of tree swallows (Tachycineta bicolor) nesting in natural cavities and compared it to that in a nestbox population. We found that 84% of females nesting in natural
cavities obtained fertilizations from extra-pair males. These extra-pair males fathered 69% of all nestlings. Studies of tree
swallows breeding in nestboxes have shown that 50–87% of broods contained extra-pair young, with extra-pair males fathering
38–53% of all the young. In broods with extra-pair paternity, natural cavities contained a significantly greater proportion
of extra-pair young than did nestboxes. Despite differences in nesting habitat and female age structure, the frequency of
extra-pair paternity did not differ significantly between the natural-cavity and nestbox populations. Therefore, the presence
of extra-pair paternity in tree swallows is not an artifact of nestboxes or of artificial nesting conditions.
Received: 2 May 1995/Accepted after revision: 14 January 1996 相似文献
999.
Lineus ruber and L. viridis are common intertidal heteronemerteans found on the coasts of northern Europe and the east coast of North America. The two species resemble each other morphologically and were synonymised for many years prior to being separated on the basis of larval development. In this study, specimens of L. ruber and L. viridis were collected from sites along the west and southwest coast of Britain, northern France and the east coast of North America. The external morphology and allele frequencies of isozymes of the two species were compared from all sites. The external morphology of L. ruber and L. viridis was similar but they could generally be separated by colour. Allele frequencies for up to 13 enzyme loci between sympatric populations of L. ruber and L. viridis indicated that these two species are genetically very different (Nei's genetic identity=0.090 to 0.083). Allele-frequency data also indicated the presence of a third genetic type occurring sympatrically with populations of both L. ruber and L. viridis on the coasts of Britain and France but not on the coast of North America. Fixed differences in allele frequencies between populations of the third genetic type and sympatric populations of L. ruber and L. viridis were observed across multiple loci. Genetic identity between the third genetic type and sympatric populations of L. ruber and L. viridis were extremely low (Nei's genetic identity =<0.078). Such large genetic differences between populations indicate a barrier to gene flow and reproductive isolation. The aberrant type, which exhibits sufficient morphological variation to prevent individuals being distinguished from those of both L. ruber and L. viridis, therefore represents a separate species. The low genetic identities found in intrageneric comparisons of species found in this study have been found in other studies on nemerteans. They may indicate systematic problems within these groups or other phenomena such as morphological stasis. 相似文献
1000.
Three recently emerging genotype classes of the genus Menippe (M. mercenaria, M. adina, and their hybrids) were examined for potential physiological correlates of gene mixing over a salinity range of 5 to 35‰.
Resting metabolic rate (RMR), as measured by oxygen uptake (V˙
O2), was highest in the hybrids. Differences in V˙
O2 could not be accounted for by differences in systemic adaptations (e.g. heart rate or scaphognathite frequency); therefore
it was concluded that they were based on potential underlying differences in carbohydrate metabolism. The higher RMR in the
hybrids was attributed to a higher metabolic cost of maintenance, resulting from the breakup of coadapted gene complexes as
a result of introgressive hybridization.
Received: 22 July 1996 / Accepted: 17 October 1996 相似文献