全文获取类型
收费全文 | 4056篇 |
免费 | 69篇 |
国内免费 | 41篇 |
专业分类
安全科学 | 187篇 |
废物处理 | 155篇 |
环保管理 | 706篇 |
综合类 | 688篇 |
基础理论 | 932篇 |
环境理论 | 3篇 |
污染及防治 | 1020篇 |
评价与监测 | 240篇 |
社会与环境 | 189篇 |
灾害及防治 | 46篇 |
出版年
2023年 | 33篇 |
2022年 | 41篇 |
2021年 | 51篇 |
2020年 | 50篇 |
2019年 | 50篇 |
2018年 | 98篇 |
2017年 | 118篇 |
2016年 | 133篇 |
2015年 | 136篇 |
2014年 | 142篇 |
2013年 | 226篇 |
2012年 | 175篇 |
2011年 | 296篇 |
2010年 | 221篇 |
2009年 | 228篇 |
2008年 | 235篇 |
2007年 | 243篇 |
2006年 | 209篇 |
2005年 | 137篇 |
2004年 | 164篇 |
2003年 | 133篇 |
2002年 | 134篇 |
2001年 | 113篇 |
2000年 | 68篇 |
1999年 | 48篇 |
1998年 | 49篇 |
1997年 | 43篇 |
1996年 | 48篇 |
1995年 | 50篇 |
1994年 | 45篇 |
1993年 | 25篇 |
1992年 | 36篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 24篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 23篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1970年 | 11篇 |
1969年 | 7篇 |
1967年 | 7篇 |
1965年 | 9篇 |
1960年 | 6篇 |
排序方式: 共有4166条查询结果,搜索用时 218 毫秒
971.
Eve?McDonald-MaddenEmail author Mark?A.?Elgar Kathrine?A.?Handasyde 《Behavioral ecology and sociobiology》2004,56(4):322-327
The costs of reproduction are widely recognised as a major selective force in the evolution of various behavioural and life-history characteristics. In particular, the behaviour of reproductively active animals is likely to change when breeding increases risk of predation. We investigated the effect of an experimentally derived threat on the vigilance and escape behaviour of female Trichosurus caninus with and without dependent offspring and at different stages of offspring development. Females with offspring showed a heightened response to the threat in comparison to females without offspring. In addition, females with offspring displayed a stronger response at earlier stages of their offsprings development.Communicated by P. Bednekoff 相似文献
972.
M. Matucha M. Gryndler S. T. Forczek H. Uhlířová K. Fuksová P. Schröder 《Environmental Chemistry Letters》2003,1(2):127-130
The fate of chloroacetic acids (CAA) in forest soils was studied using radio-indicator methods. We showed that chloroacetic acids are both microbially degraded and simultaneously formed by chloroperoxidase-mediated chlorination of acetic and humic acids. The degree of biodegradation of chloroacetic acids in soil depends on their concentration. Dichloroacetic acid (DCA) is degraded faster than trichloroacetic acid (TCA). Chlorination of acetic acid led to a fast formation of dichloroacetic acid, whereas chlorination of humic acids gave rise to trichloroacetic acid. Both processes lead to a steady state in soil, participate in the chlorine cycle and possibly also in decomposition of organic matter in forest ecosystems. 相似文献
973.
974.
Indirect Effects of Feral Horses on Estuarine Communities 总被引:1,自引:1,他引:1
Phillip S. Levin ‡ Julie Ellis Rachel Petrik Mark E. Hay† 《Conservation biology》2002,16(5):1364-1371
975.
976.
Diet induced differences in carbon isotope fractionation between sirenians and terrestrial ungulates
Carbon isotope differences (Δ13C) between bioapatite and diet, collagen and diet, and bioapatite and collagen were calculated for four species of sirenians,
Dugong dugon (Müller), Trichechus manatus (Linnaeus), Trichechus inunguis (Natterer), and the extinct Hydrodamalis gigas (Zimmerman). Bone and tooth samples were taken from archived materials collected from populations during the mid eighteenth
century (H. gigas), between 1978 and 1984 (T. manatus, T. inunguis), and between 1997 and 1999 (D. dugon). Mean Δ13C values were compared with those for terrestrial ungulates, carnivores, and six species of carnivorous marine mammals (cetaceans = 1;
pinnipeds = 4; mustelids = 1). Significant differences in mean δ13C values among species for all tissue types were detected that separated species or populations foraging on freshwater plants
or attached marine macroalgae (δ13C values < −6‰; Δ13Cbioapatite–diet ∼14‰) from those feeding on marine seagrasses (δ13C values > −4‰; Δ13Cbioapatite–diet ∼11‰). Likewise, Δ13Cbioapatite–collagen values for freshwater and algal-foraging species (∼7‰) were greater than those for seagrass-foraging species (∼5‰). Variation
in Δ13C values calculated between tissues and between tissues and diet among species may relate to the nutritional composition of
a species’ diet and the extent and type of microbial fermentation that occurs during digestion of different types of plants.
These results highlight the complications that can arise when making dietary interpretations without having first determined
species-specific Δ13Ctissue–diet values.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
977.
Jonathan Mark Wilson Alexandre Leitão Ana Filipa Gonçalves Catarina Ferreira Patrick Reis-Santos Ana-Violeta Fonseca Joana Moreira da Silva José Carlos Antunes Cristina Pereira-Wilson João Coimbra 《Marine Biology》2007,151(5):1633-1645
The Anguillid juvenile glass eel must deal with the osmoregulatory consequences of highly variable environmental salinities
on its recruitment migration from coastal to fresh waters. Changes in ionoregulatory parameters and branchial ion transport
protein [Na+/K+-ATPase, Na+:K+:2Cl− cotransporter (NKCC), cystic fibrosis transmembrane regulator (CFTR) anion channel, V-type proton ATPase] expression (activities,
protein and/or mRNA level expression and/or cellular localization) in response to acclimation to a broad range of ionic strengths
[distilled water (DW) to hypersaline water (HSW; 150%) sea water (SW 32‰)] was studied. The estuarine glass eels were very
euryhaline and successfully acclimated to acute changes in environmental ionic strength from 50% SW, with high mortality only
observed in HSW (51%) and sublethal osmoregulatory indicators (whole body water content and sodium levels) disturbed at the
extremes (DW and HSW). Central to a high salinity acclimation were elevated branchial Na+/K+-ATPase, NKCC and CFTR expression. At lower salinity, Na+/K+-ATPase expression was maintained and NKCC and CFTR expressions were reduced. Branchial chloride cells increased in size up
to SW but decreased in HSW. During hypotonic disturbance (DW), no compensatory elevation in V-ATPase or Na+/K+-ATPase expression was observed. 相似文献
978.
Charlotte K. Hemelrijk Gerard J. van Laere Jan A.R.A.M. van Hooff 《Behavioral ecology and sociobiology》1992,30(3-4):269-275
Summary In a group of captive chimpanzees (Pan troglodytes), we studied whether females received more social benefits from males when they were in oestrus than at other times and whether males distributed their beneficial acts especially to females with whom they mated more frequently. When in oestrus, females were groomed more frequently by males than at other times. There was an indication that females were groomed especially by those males with whom they mated more often. From the male point of view, the relationship between active grooming and copulation frequency held only in interactions with oestrous females. No difference was found in the male's tendency to share food with females in oestrous or anoestrous condition. Further, clear disadvantages were associated with being in oestrus: females received support from males less frequently and were more often involved in conflicts with males than in their anoestrous period. Higher ranking males did not mate more often. No relationship was found between the frequency with which a male copulated with a given female and her dominance rank, age or parity, nor did he support her or share food more often with her. 相似文献
979.
980.
Historical sea level fluctuations have influenced the genetic structure and evolutionary history of marine species and examining widespread species across their species ranges may elucidate some of these effects. Chlorurus sordidus is a common and widespread parrotfish found on coral reefs throughout the Indo-central Pacific. We used phylogenetic, phylogeographic, and cladistic analyses to examine the genetic composition and population structure of this species across most of its latitudinal range limits. We sequenced 354 bp of the mitochondrial control region I in 185 individuals from nine populations. Populations of C. sordidus displayed high levels of genetic diversity, similar to those recorded for widespread pelagic fish species, but much greater nucleotide diversity values than those previously recorded for other demersal reef fishes. Both phylogenetic and phylogeographic analyses detected strong genetic subdivision at the largest spatial scale (i.e. among oceans). The Pacific Ocean was characterised by weak population genetic structure. Separation of the Hawaiian location from other Pacific and West Indian Ocean sites was evident in phylogenetic analyses, but not from analysis of molecular variance. NCA and isolation-by-distance tests suggested that the genetic structure of this species was the result of multiple contemporary and historical processes, including long-distance colonisation and range expansion arising from fluctuating sea levels, limited current gene flow, and isolation by distance. This pattern is to be expected when historically fragmented populations come into secondary contact. We suggest the patterns of population genetic structure recorded in C. sordidus are caused by large local population sizes, high gene flow, and a recent history of repeated fragmentation and remixing of populations resulting from fluctuating sea levels.Communicated by M.S. Johnson, Crawley 相似文献