全文获取类型
收费全文 | 17187篇 |
免费 | 106篇 |
国内免费 | 114篇 |
专业分类
安全科学 | 356篇 |
废物处理 | 668篇 |
环保管理 | 1988篇 |
综合类 | 4100篇 |
基础理论 | 3875篇 |
环境理论 | 6篇 |
污染及防治 | 4243篇 |
评价与监测 | 1064篇 |
社会与环境 | 1055篇 |
灾害及防治 | 52篇 |
出版年
2022年 | 118篇 |
2021年 | 140篇 |
2019年 | 144篇 |
2018年 | 229篇 |
2017年 | 217篇 |
2016年 | 331篇 |
2015年 | 267篇 |
2014年 | 383篇 |
2013年 | 1116篇 |
2012年 | 438篇 |
2011年 | 663篇 |
2010年 | 514篇 |
2009年 | 610篇 |
2008年 | 687篇 |
2007年 | 717篇 |
2006年 | 627篇 |
2005年 | 517篇 |
2004年 | 563篇 |
2003年 | 544篇 |
2002年 | 523篇 |
2001年 | 651篇 |
2000年 | 411篇 |
1999年 | 311篇 |
1998年 | 194篇 |
1997年 | 219篇 |
1996年 | 235篇 |
1995年 | 245篇 |
1994年 | 237篇 |
1993年 | 218篇 |
1992年 | 203篇 |
1991年 | 216篇 |
1990年 | 205篇 |
1989年 | 176篇 |
1988年 | 172篇 |
1987年 | 156篇 |
1986年 | 157篇 |
1985年 | 150篇 |
1984年 | 174篇 |
1983年 | 170篇 |
1982年 | 183篇 |
1981年 | 149篇 |
1980年 | 136篇 |
1979年 | 132篇 |
1978年 | 138篇 |
1977年 | 115篇 |
1976年 | 107篇 |
1975年 | 109篇 |
1974年 | 120篇 |
1971年 | 101篇 |
1967年 | 107篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Kuselah Mae M. Tayaban Katherine L. Pintor Pierangeli G. Vital 《Environment, Development and Sustainability》2018,20(3):1311-1328
Prawn aquaculture industry is one of the developing economic activities in the Philippines. Generally, a wide range of microalgae typically grow and proliferate in many aquaculture ponds. However, certain species of microalgae have the ability to form harmful algal blooms (HABs) which often bring damaging consequences to the aquaculture industry, food safety, and the environment. The study aims to identify and characterize the composition of microalgae (particularly Cyanophyta) that are capable of forming HABs in selected freshwater prawn culture ponds in Central Luzon, Philippines, using morphological, ultrastructural, and molecular characterizations. From water samples collected in ten selected ponds across Central Luzon (Bulacan, Nueva Ecija, Pampanga, Tarlac, and Zambales), potential HAB formers such as Oscillatoria agardhii, O. princeps, Microcystis aeruginosa, and M. wesenbergii were observed to have occurred mostly, while Anabaena circinalis was only observed in one site. Both morphological and ultrastructural methods brought upon some challenges and limitations while molecular methods using 16S rRNA gene and phylogenetic analysis which were optimized in this study offered better and more efficient ways of identification and were helpful in resolving genus-level and species-level relationships. The influence of physicochemical properties of pond water, especially nutrient levels (nitrate, nitrite, and orthophosphate) on the occurrence of these cyanobacteria was also analyzed. As a pioneering study on freshwater HABs in aquaculture ponds in the country, results of the study can provide information to improve the knowledge in bloom occurrence and prediction, and to develop freshwater HAB prevention and control methods. 相似文献
162.
G. Venkatesh Åsa Nyflött Chris Bonnerup Magnus Lestelius 《Environment, Development and Sustainability》2018,20(4):1483-1497
The purpose of a barrier coating in food packaging is primarily to increase the shelf life of the foodstuff contained within the packaging, preserve its colour, odour, taste and quality, and thereby reduce food wastage (both at retail outlets and households). While most publications hitherto have compared packaging and barrier-coating materials on the basis of their environmental impacts alone, this paper adopts a more holistic approach by factoring in the economic aspect as well. Four barrier material alternatives—starch, polyethylene, EVOH + kaolin and latex + kaolin are analysed. Two well-defined end-of-life handling scenarios, relevant to Sweden, are: one in which everything except starch is recycled, with starch being composted, and the other in which everything is incinerated. Among the several environmental impact categories which can be analysed, this paper considers only global warming. Two approaches are tested to combine the economic and environmental aspects—normalisation, weighting and aggregating on the one hand, and using the carbon tax to internalise the externality caused by GHG emissions on the other. For the set of weighting factors obtained thanks to a survey conducted by the authors (40.6% for environmental and 59.4% for economic), starch emerges as the most sustainable alternative, followed by polyethylene for both the end-of-life handling scenarios. This tallies with the result obtained by using the carbon tax for internalisation of the externality. The case study, methodology and results presented in this paper, will hopefully be a springboard for more detailed studies of this nature, under the umbrella of sustainability. 相似文献
163.
Günter Gunkel Florian Selge Jonas Keitel Debora Lima Silvana Calado Maria Sobral Maricela Rodriguez Elena Matta Reinhard Hinkelmann Peter Casper Michael Hupfer 《Regional Environmental Change》2018,18(7):1913-1925
Reservoirs have a wide variety of uses that have led to frequent conflicts over ecological conservation and contamination, especially as land management has intensified. Oligotrophication must be implemented in numerous tropical reservoirs that experience advanced eutrophication to maintain aquatic ecosystem functions. To quantify impacts on ecosystem functions and to develop an adaptive management policy, multiple studies have been conducted on the Itaparica Reservoir, São Francisco River, in the semi-arid north-eastern region of Brazil. Here, we add to that existing body of knowledge through investigating how nutrient accumulation is affected by water exchange between the main river flow and Icó-Mandantes Bay. Operational water-level fluctuations in the reservoir create large desiccated littoral areas that release high amounts of nutrients when they are rewetted. In particular, water-level variation promotes proliferation of Egeria densa, a noxious weed, thus elevating trophic levels of the Itaparica Reservoir and Icó-Mandantes Bay. Analysis with a P efficiency model determined 25 μg P L?1 to be the critical concentration and further indicated that the critical load in both bodies of water have been exceeded. Moreover, intensive fish aquaculture using net cages has led to further overtaxing of the reservoir. We conclude that an effective ecological reservoir management policy must involve oligotrophication, harvesting of noxious water weeds for use as soil amendment in agriculture or biogas production, “blue” aquaculture, and limiting hydroelectric power production based on current water availability. 相似文献
164.
Hans J. M. van Grinsven Jan D. van Dam Jan Peter Lesschen Marloes H. G. Timmers Gerard L. Velthof Luis Lassaletta 《Regional Environmental Change》2018,18(8):2403-2415
This paper tests the hypothesis that relocation of pig production within the EU27 can reduce the external costs of nitrogen (N) pollution. The external cost of pollution by ammonia and nitrate from agriculture in the European Union (EU27) in 2008 was estimated at 61–215 billion € (0.5 to 1.8% of the GDP). Per capita it ranged from more than 1000 € in north-west EU27 to 50 € in Romania. The average contribution of pig production was 15%. Using provincial data (224 NUTS2 regions in EU27), the potential reduction of external N cost by relocation of pig production was estimated at 14 billion € (10% of the total). Regions most eligible for decreasing the pig stock were in western Germany, Flemish region, Denmark, the Netherlands and Bretagne, while Romania is most eligible for increasing pig production. Relocating 20 million pigs (13% of the total EU stock) decreased average external costs per capita from 900 to 785 € in the 13 NUTS2 regions where pigs were removed and increased from 69 to 107 € in 11 regions receiving pigs. A second alternative configuration of pig production was targeted at reducing exceedance of critical N deposition and closing regional nutrient cycles. This configuration relocates pigs within Germany and France, for example from Bretagne to Northern France and from Weser-Ems to Oberbayern. However, total external cost increases due to an increase of health impacts, unless when combined with implementation of best N management practices. Relocation of the pig industry in the EU27 will meet many socio-economic barriers and realisation requires new policy incentives. 相似文献
165.
E. Yu. Novenko N. G. Mazei D. A. Kupriyanov E. M. Volkova A. N. Tsyganov 《Russian Journal of Ecology》2018,49(3):218-225
Changes in the vegetation and fire regimes in the central East European Plain during the second half of the Holocene have been reconstructed based on the results of paleobotanical analysis and radiocarbon dating of material from a section of peat deposit in the Mordovia State Nature Reserve. It has been shown that birch–pine forests were widespread in the region between 7000 and 5000 yr BP, with the frequency of fires in that period being high (the fire return interval ranged from 10–20 to 100 years). Beginning from 5000 yr BP and to the early 20th century, broadleaf forests were dominant, with the fire return interval increasing to 300–500 years or longer. 相似文献
166.
167.
A. V. Ivanov M. Braun D. G. Zamolodchikov S. Yu. Loshakov O. V. Pototskii 《Russian Journal of Ecology》2018,49(4):306-311
Carbon dioxide fluxes from the surface of coarse woody debris (CWD) have been measured in Korean pine forests of the southern Sikhote-Alin mountain range. The seasonal dynamics of oxidative conversion of CWD carbon have been evaluated, and average values of the CO2 emission rate have been determined for CWD fragments of three tree species at different stages of decomposition. The degree of decomposition is an important factor of spatial variation in CO2 emission rate, and temporal variation in this parameter is adequately described by an exponential function of both CWD temperature and air temperature (R2 = 0.65–0.75). 相似文献
168.
V. G. Monakhov 《Russian Journal of Ecology》2018,49(5):434-441
The structure of commercial sable samples from the Cis-Ural region was studied taking into account hunting method (shooting or trapping). The proportion of adult animals was found to be significantly lower in samples taken during the first half of the hunting season, compared to the second half, indicating predominant harvesting of young animals. To estimate the degree of hunting selectivity (I), the ratios of demographic groups among shot and trapped animals were calculated. The results confirmed the fact of selective hunting for underyearlings both by shooting (I = 1.49–1.60 for the Cis-Ural region and I = 2.46–3.37 for the Western Sayan Mountains) and by trapping (I = 2.80–4.37), especially during the first half of winter. Samples taken during the second half of the season were characterized by prevalence of adult animals making up the reproductive core of the population (I = 1.43–2.07). It is considered that the process of reproduction in Cis-Ural sable populations in the 1960s to 1980s was stimulated by intensive commercial hunting. To maintain reproduction of sable populations at a safe level, it is necessary to reduce the period of hunting in the first quarter of the year. It is proposed to use the phenomenon of hunting selectivity for managing sable populations, regulating their exploitation, and improving the economic productivity of habitats. Commercial hunting in terms of its impact on the population can act as a factor of conscious or unconscious artificial selection. 相似文献
169.
NÁRGILA G. MOURA ALEXANDER C. LEES ALEXANDRE ALEIXO JOS BARLOW SIDNEI M. DANTAS JOICE FERREIRA MARIA DE FÁTIMA C. LIMA TOBY A. GARDNER 《Conservation biology》2014,28(5):1271-1281
Local, regional, and global extinctions caused by habitat loss, degradation, and fragmentation have been widely reported for the tropics. The patterns and drivers of this loss of species are now increasingly well known in Amazonia, but there remains a significant gap in understanding of long‐term trends in species persistence and extinction in anthropogenic landscapes. Such a historical perspective is critical for understanding the status and trends of extant biodiversity as well as for identifying priorities to halt further losses. Using extensive historical data sets of specimen records and results of contemporary surveys, we searched for evidence of local extinctions of a terra firma rainforest avifauna over 200 years in a 2500 km2 eastern Amazonian region around the Brazilian city of Belém. This region has the longest history of ornithological fieldwork in the entire Amazon basin and lies in the highly threatened Belém Centre of Endemism. We also compared our historically inferred extinction events with extensive data on species occurrences in a sample of catchments in a nearby municipality (Paragominas) that encompass a gradient of past forest loss. We found evidence for the possible extinction of 47 species (14% of the regional species pool) that were unreported from 1980 to 2013 (80% last recorded between 1900 and 1980). Seventeen species appear on the International Union for Conservation of Nature Red List, and many of these are large‐bodied. The species lost from the region immediately around Belém are similar to those which are currently restricted to well‐forested catchments in Paragominas. Although we anticipate the future rediscovery or recolonization of some species inferred to be extinct by our calculations, we also expect that there are likely to be additional local extinctions, not reported here, given the ongoing loss and degradation of remaining areas of native vegetation across eastern Amazonia. Doscientos Años de Extinciones Locales de Aves en la Amazonia Oriental 相似文献
170.
本文描述中国、印度、菲律宾和斯里兰卡能源密集和污染型工业中可以引进的一些技术变革.当选择一种新的高能效和环境无害的工业技术时需要考虑的因素中包括现行技术的状态、前期费用、运行费用、设备效率、企业内部可供利用的技能水平.为了确认一种新技术是经济上可行的,也需要考虑许多外部因素:合理能源定价的存在,是否有适用的环境法规和激励机制到位,总体金融环境,经济体系的透明度等. 相似文献