全文获取类型
收费全文 | 707篇 |
免费 | 5篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 51篇 |
环保管理 | 48篇 |
综合类 | 82篇 |
基础理论 | 149篇 |
污染及防治 | 258篇 |
评价与监测 | 69篇 |
社会与环境 | 48篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 8篇 |
2022年 | 42篇 |
2021年 | 38篇 |
2020年 | 16篇 |
2019年 | 13篇 |
2018年 | 43篇 |
2017年 | 31篇 |
2016年 | 47篇 |
2015年 | 21篇 |
2014年 | 39篇 |
2013年 | 64篇 |
2012年 | 48篇 |
2011年 | 64篇 |
2010年 | 29篇 |
2009年 | 21篇 |
2008年 | 42篇 |
2007年 | 45篇 |
2006年 | 27篇 |
2005年 | 25篇 |
2004年 | 14篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 9篇 |
1999年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1979年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有717条查询结果,搜索用时 312 毫秒
681.
682.
Eva Landová Jitka Jančúchová-Lásková Veronika Musilová Štěpánka Kadochová Daniel Frynta 《Behavioral ecology and sociobiology》2013,67(7):1113-1122
Ontogenetic changes in antipredator behavior optimize survival of growing animals. Leopard geckos (Eublepharis macularius) respond to a simulated predator either by postural and vocal threats, sometimes followed by biting, or alternatively by a rapid escape. The former “confrontational” and the latter “avoidance” behavior rarely occurs in a sequence; in fact, they represent mutually exclusive defensive strategies. We examined 552 individuals of a leopard gecko (E. macularius) of various ages, from hatching up to adulthood (31 months). Each experimental animal was exposed to a sequence of five “water-spraying” and ten “stick” (stick poking on base of the tail) stimuli, and the emitted behavior was recorded. We analyzed the effects of age, body size, body condition, adult–juvenile coloration, and sex on observed behavioral traits. The results showed that in the case of water-spraying stimulus, the usage of deterrent vocalization or escape tactic was affected by age and condition. In addition to that, using deterrent vocalization was influenced by the coloration of the animal. Stick stimulus evokes antipredator strategies that correspond with age and coloration (deterrent vocalization) and also with standardized body size (escape). Thus, leopard geckos exhibit clear ontogenetic change of defensive strategies, from threat–vocalization–bite strategy prevailing in juveniles to an escape strategy typical for adults. This behavioral change is accompanied by the ontogenetic switch of coloration from presumably warning contrasting light–dark banded pattern of juveniles to a cryptic spotted coloration of the adults. 相似文献
683.
684.
Araceli Loredo-Treviño Gerardo Gutiérrez-Sánchez Raúl Rodríguez-Herrera Cristóbal N. Aguilar 《Journal of Polymers and the Environment》2012,20(1):258-265
Plastics are present in a lot of aspects of everyday life. They are very versatile and resistant to microbial attack. Polyurethanes
are used in several industries and are divided in polyester and polyether polyurethanes and there are different types among
them. Despite their microbial resistance, they are susceptible to the attack of fungi and bacteria but the mechanism to elucidate
its biodegradation are unknown. There are reports from bacteria and fungi that are capable of degrading polyurethane but the
studies about the enzymes that attack the plastic are focused on bacterial enzymes only. The enzymes reported are of type
esterase and protease mainly since these enzymes are very unspecific and can recognize some regions in the polyurethane molecule
and hydrolyze it. Fungal enzymes have been studied prior the 1990s decade but recently, some authors report the use of filamentous
fungi to degrade polyurethane and also report some characteristics of the enzymes involved in it. This review approaches polyurethane
biodegradation by focusing on the enzymes reported to date. 相似文献
685.
Penny A. Spiering Michael J. Somers Jesús E. Maldonado David E. Wildt Micaela Szykman Gunther 《Behavioral ecology and sociobiology》2010,64(4):583-592
Although dominant African wild dogs (Lycaon pictus) are generally believed to be the sole breeders within a pack, earlier behavioral and endocrine data suggest that reproduction
could be shared with subordinates. We performed an extensive behavioral, demographic, and genetic evaluation of a wild dog
population in South Africa to examine the level of such sharing and the proximate mechanisms influencing reproductive contributions
of each sex. While a majority of pups were born to dominants because of a lack of subordinate potential breeders, we discovered
a substantial portion of reproductive sharing between dominants and subordinates. Compared with alpha females that mated annually,
subordinate beta females bred in 54.5% of years whereas thetas never bred. The three top-ranking males all sired pups (56.0%,
32.0%, and 12.0%, respectively) when three or more adult males were present. With only two pack males, alpha and beta individuals
shared reproduction nearly equally (55.2% and 44.8%, respectively), and litters of mixed paternity were discovered on eight
of 15 (53.3%) occasions. A skewed adult sex-ratio and frequent alpha mortalities for females and behavioral aggression in
males allowed most individuals to attain dominant status in their lifetime, creating a constantly shifting social hierarchy.
Genetic parentage results corresponded to reported hormone profiles, suggesting physiological suppression in some lower-ranked
individuals of both sexes. Thus, a combination of demographic, behavioral, and hormonal proximate factors mediates reproductive
partitioning in wild dogs. We conclude that reproductive sharing can be significant in this species, especially for males
that have less robust suppressive mechanisms than females. 相似文献
686.
Stephen?G.?PerzEmail author Carlos?Aramburú Jason?Bremner 《Environment, Development and Sustainability》2005,7(1):23-49
This paper discusses the linkages between population change, land use, and deforestation in the Amazon regions of Brazil, Bolivia, Colombia, Ecuador, Perú, and Venezuela. We begin with a brief discussion of theories of population–environment linkages, and then focus on the case of deforestation in the PanAmazon. The core of the paper reviews available data on deforestation, population growth, migration and land use in order to see how well land cover change reflects demographic and agricultural change. The data indicate that population dynamics and net migration exhibit to deforestation in some states of the basin but not others. We then discuss other explanatory factors for deforestation, and find a close correspondence between land use and deforestation, which suggests that land use is loosely tied to demographic dynamics and mediates the influence of population on deforestation. We also consider national political economic contexts of Amazon change in the six countries, and find contrasting contexts, which also helps to explain the limited demographic-deforestation correspondence. The paper closes by noting general conclusions based on the data, topics in need of further research and recent policy proposals.Readers should send their comments on this paper to:
BhaskarNath@aol.com within 3 months of publication of this issue 相似文献
687.
The structure, diversity and temporal distribution of the infaunal polychaetes associated with Cymodocea nodosa meadows were studied in Tenerife (Canary Islands). The samples were collected monthly throughout a year, to depths of 13–16 m. The sediment was extracted by means of PVC cores, in which four layers were separated (i.e. 0–5 cm, 5–10 cm, 10–20 cm and 20–30 cm). A total of 1,167 polychaete specimens, belonging to 69 taxa were collected, representing one of the most dominant groups in the benthic assemblage throughout the entire year. The most common families were Syllidae, Paraonidae and Spionidae, both in terms of abundance and species richness. The dominant species were Streptosyllis bidentata, Aricidea assimilis and Exogone parahomoseta mediterranea, representing also the only constant species throughout the year. The highest values of species richness, diversity, equitability and abundance of polychaetes occurred in September. The multifactorial analysis of abundances (i.e. cluster analysis and non-metric, multi-dimensional scaling) indicated temporal segregation of the samples from July, August and September (i.e. the warmest months) with respect to those from the rest of the year, due to structural differences in the assemblage. Polychaete species have been found to a depth of up to 30 cm in the sediment. Nevertheless, most of them (89%) occurred in the upper 5 cm of the sediment, with an increase of specimens in deeper layers in February (i.e. due to sporadic episodes of higher hydrodynamics). To compare the vertical distribution of polychaetes, additional core samples were collected in two seagrass meadows (i.e. C. nodosa and Ruppia cirrhosa) at Ebros Delta (NW Mediterranean); these were separated into five layers (i.e. 0–5 cm, 5–10 cm, 10–15 cm, 15–20 cm, 20–25 cm). The results obtained for the R. cirrhosa meadow (98% of the polychaetes within the upper 5 cm) agree with those for the Canarian C. nodosa meadow, while the polychaetes reached up to 15 cm depth in the Mediterranean C. nodosa meadow (i.e. ~39% between 0 and 5 cm, ~41% between 5 and 10 cm, ~20% between 10 and 15 cm). Our results indicated that the structural characteristics of the assemblages appeared to be more strongly controlled by the combined characteristics of the sediment (i.e. lack of oxygen, granulometry and degree of compaction) than by the seagrass species building the meadow.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
688.
Marín E Hernández E Bourhim S Rúa A 《Journal of the Air & Waste Management Association (1995)》2001,51(9):1346-1350
The annual average concentrations (1986-1997) of the major ions SO4(2-), NO3-, Cl-, NH4+, Na+, Mg2+, Ca2+, and K+ in precipitation are analyzed for selected EMEP stations. The objective is to determine the ion patterns or typologies in precipitation by principal component analysis (PCA) combined with a cluster analysis. SO4(2-) and NO3- ions are predominant in central and eastern Europe. This area corresponds to high emissions of SO2 and NO2. Sea spray ions are predominant in coastal sites. The soil components show an important contribution in southern Europe, possibly due to the soil dust transported from northern Africa. 相似文献
689.
J. Ojeda Zújar L. Borgniet A. M. Pérez Romero J. F. Loder 《Journal of Coastal Conservation》2002,8(1):69-76
This contribution deals with the use of different sources of data (field surveys with total station and GPS, air photographs
and topographic maps) as well as their integrated digital treatment in a GIS context to quantify the morphological changes
in a ridge of coastal dunes in the southwest of Spain. The results show very high and increm enting rates of foredune retreat
significant losses of foredune surface and a clear negative sedimentary balance (lowering and inland migration) in its recent
evolution (1979–1996). Two processes can explain this evolution: (1) marine erosion and (2) the reactivation of aeolian deflation.
The combined use of GPS (code/phase) and soft-copy photogrammetry seem to provide the best for monitoring future changes. 相似文献
690.
Water quality levels and loads of nutrients transported by the Agüera stream (northern Spain) were studied for a year to assess
the self-purification capacity of this system. The main villages produce an increase of nutrient concentrations and a degradation
of water quality. Nevertheless, the high retention capacity, especially for phosphate, allows the stream to recover its previous
levels of quality after a short reach. The retention of nutrients depends on a complex combination of the flow level, hydrologic
stability and the development of periphytic communities. 相似文献