全文获取类型
收费全文 | 2349篇 |
免费 | 18篇 |
国内免费 | 20篇 |
专业分类
安全科学 | 64篇 |
废物处理 | 100篇 |
环保管理 | 253篇 |
综合类 | 890篇 |
基础理论 | 370篇 |
环境理论 | 2篇 |
污染及防治 | 473篇 |
评价与监测 | 136篇 |
社会与环境 | 92篇 |
灾害及防治 | 7篇 |
出版年
2022年 | 27篇 |
2021年 | 32篇 |
2020年 | 21篇 |
2019年 | 23篇 |
2018年 | 41篇 |
2017年 | 42篇 |
2016年 | 35篇 |
2015年 | 39篇 |
2014年 | 52篇 |
2013年 | 98篇 |
2012年 | 93篇 |
2011年 | 104篇 |
2010年 | 70篇 |
2009年 | 91篇 |
2008年 | 79篇 |
2007年 | 102篇 |
2006年 | 76篇 |
2005年 | 83篇 |
2004年 | 90篇 |
2003年 | 73篇 |
2002年 | 69篇 |
2001年 | 42篇 |
2000年 | 28篇 |
1999年 | 21篇 |
1998年 | 33篇 |
1997年 | 17篇 |
1996年 | 22篇 |
1995年 | 32篇 |
1994年 | 24篇 |
1993年 | 16篇 |
1992年 | 20篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1965年 | 17篇 |
1964年 | 15篇 |
1963年 | 25篇 |
1962年 | 18篇 |
1961年 | 14篇 |
1960年 | 23篇 |
1959年 | 24篇 |
1958年 | 16篇 |
1957年 | 16篇 |
1956年 | 14篇 |
1955年 | 28篇 |
1954年 | 33篇 |
1953年 | 19篇 |
1952年 | 14篇 |
1951年 | 24篇 |
排序方式: 共有2387条查询结果,搜索用时 31 毫秒
971.
Thomas K. Rudel Birthe Paul Douglas White I. M. Rao Rein Van Der Hoek Aracely Castro Maryline Boval Amy Lerner Laura Schneider Michael Peters 《Ambio》2015,44(7):685-693
The increased use of grain-based feed for livestock during the last two decades has contributed, along with other factors, to a rise in grain prices that has reduced human food security. This circumstance argues for feeding more forages to livestock, particularly in the tropics where many livestock are reared on small farms. Efforts to accomplish this end, referred to as the ‘LivestockPlus’ approach, intensify in sustainable ways the management of grasses, shrubs, trees, and animals. By decoupling the human food and livestock feed systems, these efforts would increase the resilience of the global food system. Effective LivestockPlus approaches take one of two forms: (1) simple improvements such as new forage varieties and animal management practices that spread from farmer to farmer by word of mouth, or (2) complex sets of new practices that integrate forage production more closely into farms’ other agricultural activities and agro-ecologies. 相似文献
972.
A. D. Pokarzhevskii N. M. Van Straalen Zh. V. Filimonova A. S. Zaitsev R. O. Butovskii 《Russian Journal of Ecology》2000,31(3):190-197
Studies on the ecotoxicology of soil organisms have led to the revision of views on the trophic structure of ecosystems. It
was found that the microbial link is obligatory and controls the migration of toxicants and their effects in the food chain.
Differences in effects are accounted for by both the physiological stability of organisms and their affliation with relatively
independent and biogeochemically closed ecosystems differing in their spatiotemporal scales. The latter form a hierarchical
three-level structure: ecosystems of unicellular organisms—ecosystems of small multicellular organisms—the ecosystem of large
multicellular organisms, or of biogeocenosis. Trophic networks within the structure are united by ecosystemophagy as the type
of feeding of large multicellular organisms, and this accounts for the importance of the latter as indicators of long-term
changes in a biogeocenosis. 相似文献
973.
Tadesse Getahun Mulat Gebrehiwot Argaw Ambelu Tom Van Gerven Bart Van der Bruggen 《Environmental monitoring and assessment》2014,186(7):4637-4646
The objective of this study was to estimate the potential of organic municipal solid waste generated in an urban setting in a tropical climate to produce biogas. Five different categories of wastes were considered: fruit waste, food waste, yard waste, paper waste, and mixed waste. These fractions were assessed for their efficiency for biogas production in a laboratory-scale batch digester for a total period of 8 weeks at a temperature of 15–30 °C. During this period, fruit waste, food waste, yard waste, paper waste, and mixed waste were observed to produce 0.15, 0.17, 0.10, 0.08, and 0.15 m3 of biogas per kilogram of volatile solids, respectively. The biogas produced and caloric value of each feedstock was in the range of 1.25?×?10?3 m3 (17 kWh)/cap/day (paper waste) to 15?×?10?3 m3 (170 kWh)/cap/day (mixed waste). Paper waste produced the least (<1×10?3(<17.8 kWh)/cap/day), and mixed waste produced the highest methane yield (10?×?10?3 m3 (178 kWh)/cap/day). Thus, mixed waste was found to be more efficient than other feedstocks for biogas and methane production; this was mainly related to the better C/N ratio in mixed waste. Taking the total waste production in Jimma into account, the total mixed organic solid waste could produce 865?×?103 m3 (5.4 m3/capita) of biogas or 537?×?103 m3 (3.4 m3/capita) of methane per year. The total caloric value of methane production potential from mixed organic municipal solid waste was many times higher than the total energy requirement of the area. 相似文献
974.
Patrik Fauser Hans Sanderson Rikke V. Hedegaard Jens J. Sloth Martin M. Larsen Teddy Krongaard Rossana Bossi Jørn B. Larsen 《Environmental monitoring and assessment》2013,185(6):4679-4691
The content of total arsenic, the inorganic forms: arsenite (As(III)) and arsenate (As(V)), the methylated forms: monomethylarsonic acid and dimethylarsinic acid (DMA), trimethylarsenic oxide, tetramethylarsenonium ion and arsenobetaine was measured in 95 sediment samples and 11 pore water samples from the Baltic Sea near the island of Bornholm at depths of up to 100 m. As(III+V) and DMA were detected in the sediment and As(III+V) was detected in the sediment pore water. Average total As concentration of 10.6?±?7.4 mg/kg dry matter (DM) in the sediment corresponds to previously reported values in the Baltic Sea and other parts of the world. Existing data for on-site measurements of sorption coefficients (Kd) of arsenicals in marine and freshwater sediments show large variability from <1 to >1,000 L/kg. In this work, calculated sorption coefficients (Kd and Koc) for As(III+V) showed significant correlation with depth, dissolved oxygen (DO), salinity and sediment classification; for depths <70 m, salinity <11 %, DO >9 mg/L and sand/silt/clay sediments the Kd was 118?±?76 L/kg DM and for depths >70 m, salinity >11 %, DO?<?9 mg/L and muddy sediments the Kd was 513?±?233 L/kg DM. The authors recommend using the found Kd value for arsenic in marine sediments when conditions are similar to the Baltic Sea. At locations with significant anthropogenic point sources or where the local geology contains volcanic rock and sulphide mineral deposits, there may be significantly elevated arsenic concentrations, and it is recommended to determine on-site Kd values. 相似文献
975.
Nguyen Van Hop Hoang Thi Quynh Dieu Nguyen Hai Phong 《Environmental monitoring and assessment》2017,189(6):299
The concentrations of seven toxic metals (cadmium (Cd), nickel (Ni), chromium (Cr), arsenic (As), lead (Pb), copper (Cu), and zinc (Zn)) were determined in sediments and the soft tissues of a bivalve species (Meretrix lyrata) collected from the Tien Estuary in Tien Giang Province, South Vietnam. The total metal concentrations in sediments (mg/kg dry weight) increased as Cd (0.06) < Cu (5.0) < Pb (13.9) < As (16.3) < Ni (24) < Cr (50) < Zn (62). Speciation analysis revealed that these metals existed mainly in the residual fraction (43–94%), followed by the Fe-Mn oxide-bound (5–35%) and organic/sulfide-bound (0.6–9.2%) fractions. The metal concentrations in M. lyrata (mg/kg dry weight) were in the ranges of 1.3–1.9 (Cd), 1.5–2.8 (Ni), 1.8–3.4 (Cr), 11–16 (As), 0.3–0.6 (Pb), 6.9–8.7 (Cu), and 95–128 (Zn), which are safe for human consumption. The order of the mean biota-sediment accumulation factor (BSAF) of the metals in the non-residual fractions of the sediment for M. lyrata was Cd > Cu > As > Zn > Cr > Ni > Pb. The Risk Assessment Codes (RACs) suggest that the highest mobility of Cd (with RAC = 37%) poses greater environmental risk to aquatic biota. Correlation analysis results show that M. lyrata can be used as a biomonitor of Cd and Cu pollution in the exchangeable, acid-soluble, and non-residual sediment fractions. 相似文献
976.
Wolfgang Schaaf Michael Elmer Anton Fischer Werner Gerwin Rossen Nenov Hans Pretzsch Stefan Seifert Susanne Winter Markus Klemens Zaplata 《Environmental monitoring and assessment》2013,185(7):5965-5986
The objective of this paper is to present observations, results from monitoring measurements, and preliminary conclusions about the development of patterns and structures during the first 5 years of development of an artificial catchment starting from point zero. We discuss the high relevance of initial system traits and external events for the system development and draw conclusions for further research. These investigations as part of a Collaborative Research Center, aim to disentangle and understand the feedback mechanisms and interrelationships of processes and their co-development with spatial and temporal structures and patterns by studying an initial, probably less complex ecosystem. Therefore, intensive measurements were carried out in the catchment with regard to the development of surface structures, hydrological patterns, vegetation dynamics, water chemistry, and element budgets. During the first 5 years, considerable changes within the catchment were observed. Both internal and external factors could be identified as driving forces for the formation of structures and patterns in the artificial catchment. Initial structures formed by the construction process and initial substrate characteristics were decisive for the distribution and flow of water. External factors like episodic events triggered erosion and dissection during this initial phase, promoted by the low vegetation cover, and the unconsolidated sandy substrate. The transformation of the initial geosystem into areas with evolving terrestrial or aquatic characteristics and from a very episodic to a more permanent stream network and discharge, together with the observed vegetation dynamics increased site diversity and heterogeneity with respect to water and nutrient availability and transformation processes compared with the more homogenous conditions at point zero. The processes and feedback mechanisms in the initial development of a new landscape may deviate in rates, intensity, and dominance from those known from mature ecosystems. It is therefore crucial to understand these early phases of ecosystem development and to disentangle the increasingly complex interactions between the evolving terrestrial and aquatic, biotic, and abiotic compartments of the system. Long-term monitoring of initial ecosystems may provide important data and parameters on processes and the crucial role of spatial and temporal structures and patterns to solve these problems. Artificially created catchments could be a suitable tool to study these initial developments at the landscape scale under known, designed, and defined boundary conditions. 相似文献
977.
M. M. Lyons P. Aas J. D. Pakulski L. Van Waasbergen R. V. Miller D. L. Mitchell W. H. Jeffrey 《Marine Biology》1998,130(3):537-543
Ultraviolet radiation (UVR) has been implicated in coral-bleaching processes and UVR may create stress to marine organisms
by damage to DNA. Absorption of energy from UVB (280 to 320 nm) induces direct damage to DNA via cyclobutane pyrimidine dimer
photoproduct-formation. We examined the extent of DNA damage created by UVR in coral reef microbial communities and whether
the coral-surface microlayer (CSM) provides protection from UVR to the microorganisms found there. Diel patterns and depth
profiles of UVR effects were examined in coral mucus (coral-surface microlayer, CSM) from Montastraea faveolata and Colpophyllia natans, and water-column samples of similar depths. UV-induced photodamage was determined using a radioimmunoassay specific for
cyclobutane pyrimidine dimers (thymine dimers). Significant photodamage was detected in water-column and CSM samples, although
the level of damage in CSM samples was consistently lower than in water-column samples collected from the same depth, suggesting
the presence of photoprotective mechanisms within the CSM. Diel patterns of photodamage were detected in both water-column
and CSM samples, but peak damage occurred earlier in the day for the CSM samples, suggesting differences in damage and repair
kinetics between the water column and CSM. The results suggest that microorganisms within the CSM are afforded some protection
from UVR stress and that changes in the amount of DNA damage in these organisms may be an indicator of changing UVR stress
to corals.
Received: 10 January 1997 / Accepted: 15 September 1997 相似文献
978.
Sexual conflict over fertilizations: female bluethroats escape male paternity guards 总被引:5,自引:0,他引:5
Arild Johnsen Jan T. Lifjeld Percy A. Rohde Craig R. Primmer Hans Ellegren 《Behavioral ecology and sociobiology》1998,43(6):401-408
Extra-pair copulations create a potential for sexual conflict in pair-bonding birds. Here we report an experimental study
of the bluethroat, Luscinia s. svecica, in which the throat ornament of males was blackened with Nyanzol D in order to reduce their sexual attractiveness and thus
increase the sexual conflict over fertilizations. In an earlier study, we showed that males blackened before pairing had a
lower success in attracting social mates than controls, whereas males blackened after pairing guarded their mates more intensely
and sang less than controls. Here we add behavioural data from one more year on males blackened after pairing and corroborate
our previous finding that the manipulation caused males to guard their mates more intensely and advertise less for additional
mates. Blackened males did not suffer more intrusions from neighbouring males than did controls. Paternity analyses of the
combined data set, using multilocus DNA fingerprinting and microsatellite typing, revealed that blackened males lost significantly
more paternity than controls. There was also a tendency for blackened males to show a lower success in achieving extra-pair
fertilizations. These results indicate that females have the upper hand in the sexual conflict over fertilizations, as females
paired with unattractive males can achieve more extra-pair paternity despite the greater constraint posed by the intensified
mate guarding. Still, within the blackened group, there were some indications that males guarding more intensely and singing
less had higher paternity than males guarding less and singing more, suggesting a marginal positive effect of guarding for
unattractive males. Male mate guarding must nevertheless be considered a best-of-a-bad-job strategy in this species.
Received: 4 December 1997 / Accepted after revision: 14 June 1998 相似文献
979.
A.H.W. Beusen A.F. Bouwman P.S.C. Heuberger G. Van Drecht K.W. Van Der Hoek 《Atmospheric environment (Oxford, England : 1994)》2008,42(24):6067-6077
Here we present an uncertainty analysis of NH3 emissions from agricultural production systems based on a global NH3 emission inventory with a 5×5 min resolution. Of all results the mean is given with a range (10% and 90% percentile). The uncertainty range for the global NH3 emission from agricultural systems is 27–38 (with a mean of 32) Tg NH3-N yr−1, N fertilizer use contributing 10–12 (11) Tg yr−1 and livestock production 16–27 (21) Tg yr−1. Most of the emissions from livestock production come from animal houses and storage systems (31–55%); smaller contributions come from the spreading of animal manure (23–38%) and grazing animals (17–37%). This uncertainty analysis allows for identifying and improving those input parameters with a major influence on the results. The most important determinants of the uncertainty related to the global agricultural NH3 emission comprise four parameters (N excretion rates, NH3 emission rates for manure in animal houses and storage, the fraction of the time that ruminants graze and the fraction of non-agricultural use of manure) specific to mixed and landless systems, and total animal stocks. Nitrogen excretion rates and NH3 emission rates from animal houses and storage systems are shown consistently to be the most important parameters in most parts of the world. Input parameters for pastoral systems are less relevant. However, there are clear differences between world regions and individual countries, reflecting the differences in livestock production systems. 相似文献
980.
Sampling method, storage and pretreatment of sediment affect AVS concentrations with consequences for bioassay responses 总被引:1,自引:0,他引:1
De Lange HJ Van Griethuysen C Koelmans AA 《Environmental pollution (Barking, Essex : 1987)》2008,151(1):243-251
Sediment treatment and sediment storage may alter sediment toxicity, and consequently biotic response. Purpose of our study was to combine these three aspects (treatment-toxicity-biotic response) in one integrated approach. We used Acid Volatile Sulfide (AVS) concentrations as a proxy of the disturbance of the sediment. AVS and Simultaneously Extracted Metal (SEM) concentrations were compared to bioassay responses with the freshwater benthic macroinvertebrate Asellus aquaticus. Storage conditions and sediment treatment affected AVS but not SEM levels. AVS can be used as a proxy for sediment disturbance. The best way to pretreat the sediment for use in a bioassay in order to maintain initial AVS conditions was to sample the sediment with an Ekman grab, immediately store it in a jar without headspace, and freeze it as soon as possible. In a survey using seven different sediments, bioassay responses of A. aquaticus were correlated with SEM and AVS characteristics. 相似文献