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991.
目前,我国生态补偿机制依旧存在法规不健全、体系不科学的问题,无法满足当下水土保持工作的整体要求。本文主要针对当下生态补偿机制存在的问题,阐明建立健全生态补偿机制的必要性,并进一步提出相应的机制完善措施,以望为未来水土保持工作提供参考。 相似文献
992.
Arctic ecosystems have experienced and are projected to experience continued large increases in temperature and declines in
sea ice cover. It has been hypothesized that small changes in ecosystem drivers can fundamentally alter ecosystem functioning,
and that this might be particularly pronounced for Arctic ecosystems. We present a suite of simple statistical analyses to
identify changes in the statistical properties of data, emphasizing that changes in the standard error should be considered
in addition to changes in mean properties. The methods are exemplified using sea ice extent, and suggest that the loss rate
of sea ice accelerated by factor of ~5 in 1996, as reported in other studies, but increases in random fluctuations, as an
early warning signal, were observed already in 1990. We recommend to employ the proposed methods more systematically for analyzing
tipping points to document effects of climate change in the Arctic. 相似文献
993.
Fates and transport of 9 commonly found PPCPs of the reclaimed water were simulated based on the HYDRUS-1D software that was validated with data generated from field experiments. Under the default scenario in which the model parameters and input data represented the typical conditions of turf grass irrigation in southern California, the adsorption, degradation, and volatilization of clofibric acid, ibuprofen, 4-tert-octylphenol, 4-n-nonylphenol, naproxen, triclosan, diclofenac sodium, bisphenol A and estrone in the receiving soils were tracked for 10 years. At the end, their accumulations in the 90 cm soil profile varied from less than 1 ng g−1 to about 140 ng g−1 and their concentrations in the drainage water in the 90 cm soil depth varied from nil to μg L−1 levels. The adsorption and microbial degradation processes interacted to contain the PPCPs entirely within surface 40 cm of the soil profiles. Leaching and volatilization were not significant processes governing the PPCPs in the soils. The extent of accumulations in the soils did not appear to produce undue ecological risks to the soil biota. PPCPs did not represent any potential environmental harm in reclaimed water irrigation. 相似文献
994.
Based on the theory of ecological footprint this paper analyzed the ecological economic system in Funing County in the view
of demands of economic system to natural resource and supply of ecosystem for natural resources. It was proposed that the
concept of ecological deficit (ecological remainder) per ten thousands yuan GDP be used to evaluate development of ecological
economic system. With a synthesis appraisement to the ecological economic system using entire-array-polygon method combined
with Ulanowicz development ability and with ecological deficit (ecological remainder) per ten thousands yuan GDP, it provids
a theoretical base for reconstructing and managing of demonstration eco-region. 相似文献
995.
Zhang W 《Environmental monitoring and assessment》2007,124(1-3):253-261
Both direct and indirect ecological interactions may occur in an ecosystem with large numbers of taxa. Traditional food web
technique is a popular tool to measure the quality and health of the environment. Much of works must be done before constructing
a food web for an ecosystem especially with many taxa. This food web is generally specific for some ecological interactions
and fixed for a set of given species. It is therefore not an effective method for dynamic and prompt assessment of environment.
Ecological interactions and their interactive intensity may be detected by sampling biological taxa in the field and by detecting
various between-taxa distances or similarities. Network may clearly exhibit the complex interactions among biological taxa.
Statistic tests on various distance or similarity measures and computer designs are required to infer the {network. We develop
an algorithm and software to infer the network of direct or indirect ecological interactions in ecosystem. It is a prompt
and effective tool in monitoring and assessment of the environment. A redundant network may be inferred and drawn by computer
based on the statistic tests on sampling data or the pathway information given in HTML file. Dominant taxa may be found in
the network. In total of 16 distance and similarity measures, including Euclidean distance, Manhattan distance, Pearson correlation,
partial correlation, point correlation, linkage coefficients, Jaccard coefficient etc., are provided to detect taxa pairs
with significant parametric or nonparametric similarities, based on randomization tests and ordinary statistic tests. Criteria
to use distance and similarity measures are discussed. 相似文献
996.
The aim of this study is to determine the total metal (aluminum, copper, manganese, nickel, lead, zinc, cadmium, iron, mercury) contents of dominant shrimp species and sediments present at 1–50 m depths of the Northern Inner Shelf of the Sea of Marmara. Shrimp and sediment samples were collected from four regions (Büyükçekmece, Silivri, Tekirda?, ?arköy) and from different depths (1, 5, 10, 20, 30, 50 m) at each region in September and November of 2003. Three shrimp species [Palaemon adspersus (Rathke, 1937), Palaemon serratus (Pennant, 1777), Parapenaeus longirostris (H. Lucas, 1846)] were identified to be dominant as a result of the examination on the obtained samples. Heavy metal contents of these three species were determined and the results were compared with the acceptable treshold values of the Seafood Standards and also with available literatures. The Cu contents were found to be higher than the treshold limits in all samples except P. longirostris from Silivri, also the Cd contents in all samples except P. adspersus from Büyükçekmece, the Zn contents only in P. adspersus and P. longirostris from Tekirda?, and the Pb contents in all species from all regions. These high values are the indicator of industrial pollution. There is not any data in the Seafood Standards about Mn, Ni, Fe and Al contents in shrimp species. The values of these metal contents were given in the present study. The examination of total metal distributions in bottom surface sediment samples in the Northern Inner Shelf of the Sea of Marmara showed that the determined values were higher than the shale average at some depths of examined stations. 相似文献
997.
We used interdemic variation in the tendency to form mixed-species groups to examine the costs and benefits of association
among the primates of Kibale National Park, Uganda. A year-long survey of six sites revealed that the amount of time that
the five common diurnal primates [red colobus (Procolobus
tephrosceles), black-and-white colobus (Colobus
guereza), redtail monkeys (Cercopithecus
ascanius), blue monkeys (Cercopithecus
mitis), and grey-cheeked mangabeys (Lophocebus
albigena)] spent in mixed-species groups varied dramatically among sites. In many cases, the proportion of time that species associated
was positively related to their densities. By using detailed behavioral observations of redtail monkeys and red colobus made
over 4 years (2660 h) at four sites, we were able to reject the null hypothesis that associations occur by chance for only
one of four sites. However, a correlative approach exploring the costs and benefits of association suggests that ecological
variables do influence association patterns. We found that redtail monkeys and red colobus overlapped in diet (19.2% of their
foraging effort) and traveled further when in mixed-species groups than when alone. Having demonstrated this, we examined
the applicability of the ecological constraints model for predicting the proportion of the time spent in mixed-species groups
based on food availability. For this analysis we concentrated on red colobus from the site with 35 months of observation and
demonstrated that their tendency to be in mixed- species groups was related to food availability. We used two methods to examine
if mixed-species associations function to decrease predation risk. First, chimpanzees are known to prey heavily on red colobus,
but rarely kill other primates. The time red colobus spent in mixed-species groups was correlated to chimpanzee density, but
it was not for the other monkey species, suggesting that mixed-species groups serve to decrease predation risk. Second, when
red colobus groups contain more infants and are presumably at the greatest risk of predation, they form mixed-species groups
most often. These results demonstrate that the costs and benefits of mixed-species associations vary dramatically over small
spatial and temporal scales. If such variation is generally the case, then studies conducted at different locations or different
times could easily highlight the importance of difference selective agents in favoring mixed-species associations.
Received: 10 February 1999 / Received in revised form: 16 September 1999 / Accepted: 2 October 1999 相似文献
998.
本溪县农业面源污染现状及防治对策 总被引:4,自引:1,他引:3
通过科学的调研数据,重点分析了本溪县农药、化肥和农膜造成的环境污染。调查结果表明,本溪县农药、化肥和农膜的大量施用,虽然可以提高农作物的产量,但也会对人、土地、水体和生物等产生诸多不利的影响,从而提出相应的治理对策。建议发展生态农业,加强监督管理,研究制定相应的污染控制政策与措施。 相似文献
999.
景观水体富营养化模拟过程中藻类演替及多样性指数研究 总被引:2,自引:0,他引:2
采用微宇宙培养法,模拟微污染景观水体富营养化过程,研究其浮游藻类演替状况及生物多样性指数结果表明,最终优势藻种为黄藻门.通过计算9种生物多样性指数(Margalef's、PIE(种间相遇几率)、Menhinick's、Shannon-wiener、Simpson's、McNaughton's dominance index、Species、OD(多样性测度指数)、Monk)对景观水体富营养化过程中浮游植物演替趋势进行评价,发现其中仅2种多样性指数适于静态景观水体富营养化研究,分别为Monk多样性指数及Menhinick's多样性指数,而其它指数都不够准确. 相似文献
1000.
Marine protected areas (MPAs) have become a key component of conservation and fisheries management to alleviate anthropogenic pressures. For MPA networks to efficiently promote persistence and recovery of populations, ecological connectivity, i.e. dispersal and movement of organisms and material across ecosystems, needs to be taken into account. To improve the ecological coherence of MPA networks, there is hence a need to evaluate the connectivity of species spreading through active migration and passive dispersal. We reviewed knowledge on ecological connectivity in the Baltic Sea, Kattegat and Skagerrak in the northeast Atlantic and present available information on species-specific dispersal and migration distances. Studies on genetic connectivity are summarised and discussed in relation to dispersal-based analyses. Threats to ecological connectivity, limiting dispersal of populations and lowering the resilience to environmental change, were examined. Additionally, a review of studies evaluating the ecological coherence of MPA networks in the Baltic Sea, Kattegat and Skagerrak was performed, and suggestions for future evaluations to meet management needs are presented.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01684-x. 相似文献