全文获取类型
收费全文 | 5066篇 |
免费 | 39篇 |
国内免费 | 14篇 |
专业分类
安全科学 | 74篇 |
废物处理 | 277篇 |
环保管理 | 295篇 |
综合类 | 1190篇 |
基础理论 | 902篇 |
环境理论 | 4篇 |
污染及防治 | 1550篇 |
评价与监测 | 448篇 |
社会与环境 | 256篇 |
灾害及防治 | 123篇 |
出版年
2023年 | 47篇 |
2022年 | 139篇 |
2021年 | 173篇 |
2020年 | 97篇 |
2019年 | 60篇 |
2018年 | 179篇 |
2017年 | 123篇 |
2016年 | 229篇 |
2015年 | 119篇 |
2014年 | 279篇 |
2013年 | 447篇 |
2012年 | 318篇 |
2011年 | 281篇 |
2010年 | 213篇 |
2009年 | 160篇 |
2008年 | 258篇 |
2007年 | 386篇 |
2006年 | 355篇 |
2005年 | 197篇 |
2004年 | 126篇 |
2003年 | 160篇 |
2002年 | 117篇 |
2001年 | 77篇 |
2000年 | 53篇 |
1999年 | 37篇 |
1998年 | 16篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 25篇 |
1994年 | 21篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1982年 | 11篇 |
1970年 | 8篇 |
1967年 | 8篇 |
1966年 | 11篇 |
1965年 | 16篇 |
1964年 | 29篇 |
1963年 | 13篇 |
1962年 | 17篇 |
1961年 | 14篇 |
1960年 | 14篇 |
1959年 | 31篇 |
1958年 | 33篇 |
1957年 | 21篇 |
1956年 | 19篇 |
1955年 | 18篇 |
1954年 | 9篇 |
排序方式: 共有5119条查询结果,搜索用时 15 毫秒
901.
Alex Ibáñez Alfonso Marzal Pilar López José Martín 《Behavioral ecology and sociobiology》2013,67(4):541-548
Recognition and avoidance of conspecifics based on chemical cues could reduce the risk of aggressive interactions between males. Success in agonistics encounters with unfamiliar males should be lower than with previously known familiar males. Then, males should avoid the chemicals from unfamiliar males with respect to those from familiar males. However, boldness and size could affect the outcome of encounters between males and, consequently, the response to chemical cues of conspecific males. We compared the time spent by male turtles Mauremys leprosa in water pools with chemical stimuli from unfamiliar or familiar males or with their own chemical stimuli. We also performed a behavioral test to estimate boldness of turtles in an antipredatory situation. Turtles avoided the chemicals from unfamiliar males respect to familiar ones and their own odors, but their responses depended on boldness and size of the tested turtle. Bold turtles avoided water with chemicals of unfamiliar males, but not with chemicals of familiar males, whereas shy turtles avoided chemicals of both familiar and unfamiliar males. On the other hand, large males avoided the odor from unfamiliar males, but small males did not avoid water with the odor from other males. Results suggest that male M. leprosa can detect chemicals released to water from conspecific males and discriminate between familiar and unfamiliar males. However, responses to these chemicals depended on boldness and body size of the responding turtle because these factors may affect intrasexual competition. 相似文献
902.
903.
Ana Širović Lauren N. Williams Sara M. Kerosky Sean M. Wiggins John A. Hildebrand 《Marine Biology》2013,160(1):47-57
Fin whales (Balaenoptera physalus) produce a variety of low-frequency, short-duration, frequency-modulated calls. The differences in temporal patterns between two fin whale call types are described from long-term passive acoustic data collected intermittently between 2005 and 2011 at three locations across the eastern North Pacific: the Bering Sea, off Southern California, and in Canal de Ballenas in the northern Gulf of California. Fin whale calls were detected at all sites year-round, during all periods with recordings. At all three locations, 40-Hz calls peaked in June, preceding a peak in 20-Hz calls by 3–5 months. Monitoring both call types may provide a more accurate insight into the seasonal presence of fin whales across the eastern North Pacific than can be obtained from a single call type. The 40-Hz call may be associated with a foraging function, and temporal separation between 40- and 20-Hz calls may indicate the separation between predominately feeding behavior and other social interactions. 相似文献
904.
Paula Méndez-Fernandez Graham J. Pierce Paco Bustamante Tiphaine Chouvelon Marisa Ferreira Angel F. González Alfredo López Fiona L. Read M. Begoña Santos Jérôme Spitz José V. Vingada Florence Caurant 《Marine Biology》2013,160(11):2825-2840
This study aims to assess niche segregation among the five main toothed whales that frequent the NW Iberian Peninsula waters: the common dolphin, the harbour porpoise, the bottlenose dolphin, the striped dolphin and the long-finned pilot whale. We used cadmium (Cd) and stable isotope ratios (δ13C and δ15N) as ecological tracers to assess degree of segregation in diet/trophic level and in foraging habitat, over various time-scales. δ13C values highlighted different habitats, while Cd concentrations highlighted feeding differences between oceanic and neritic species. Moreover, δ15N values suggest different trophic levels of prey targeted within oceanic and neritic species. Hence, results revealed long-term ecological segregation among five toothed whales that coexist in the NWIP and demonstrated the ability of ecological tracers to discriminate ecological niches among closely related species. 相似文献
905.
Nikola M. Pavlović Vuk Maksimović Jelena Dragišić Maksimović William H. Orem Calin A. Tatu Harry E. Lerch Joseph E. Bunnell Emina N. Kostić Diana N. Szilagyi Virgil Paunescu 《Environmental geochemistry and health》2013,35(2):215-226
Aristolochic acids (AAs) are nephrotoxic and carcinogenic derivatives found in several Aristolochia species. To date, the toxicity of AAs has been inferred only from the effects observed in patients suffering from a kidney disease called “aristolochic acid nephropathy” (AAN, formerly known as “Chinese herbs nephropathy”). More recently, the chronic poisoning with Aristolochia seeds has been considered to be the main cause of Balkan endemic nephropathy, another form of chronic renal failure resembling AAN. So far, it was assumed that AAs can enter the human food chain only through ethnobotanical use (intentional or accidental) of herbs containing self-produced AAs. We hypothesized that the roots of some crops growing in fields where Aristolochia species grew over several seasons may take up certain amounts of AAs from the soil, and thus become a secondary source of food poisoning. To verify this possibility, maize plant (Zea mays) and cucumber (Cucumis sativus) were used as a model to substantiate the possible significance of naturally occurring AAs’ root uptake in food chain contamination. This study showed that the roots of maize plant and cucumber are capable of absorbing AAs from nutrient solution, consequently producing strong peaks on ultraviolet HPLC chromatograms of plant extracts. This uptake resulted in even higher concentrations of AAs in the roots compared to the nutrient solutions. To further validate the measurement of AA content in the root material, we also measured their concentrations in nutrient solutions before and after the plant treatment. Decreased concentrations of both AAI and AAII were found in nutrient solutions after plant growth. During this short-term experiment, there were much lower concentrations of AAs in the leaves than in the roots. The question is whether these plants are capable of transferring significant amounts of AAs from the roots into edible parts of the plant during prolonged experiments. 相似文献
906.
Aquatic macrophytes can be used in the studies of quality of water ecosystems and in monitoring of metals and other pollutants. The aim of this study was to assess concentration levels, accumulation and distribution of seven metals in selected plant parts of Typha angustifolia L. and Iris pseudacorus L., in comparison with sediment and water samples of a reservoir. Metal content in the samples was determined by optical emission spectrometry (ICP-OES iCAP 6500). The concentrations of all examined metals were higher in the sediment than in the water samples. In plants, metal concentrations depended on plant species and organs. The roots/rhizomes were primary organs for metal concentration and accumulation. T. angustifolia L. accumulated Mn and Cu, and I. pseudacorus L. accumulated Cd and Cu in the fruits. T. angustifolia L. hyperaccumulated As. The values of enrichment coefficients and translocation factors were: 0 to 3.31 and 0 to 2.39, respectively. The plant species investigated absorb, translocate and accumulate metals in their organs differently, which provides advantages in combining them for remediation of wasted aquatic ecosystems. 相似文献
907.
E. T. Romero-Guzmán L. R. Reyes-Gutiérrez M. J. Marín-Allende Z. I. González-Acevedo M. T. Olguín-Gutiérrez 《Chemistry and Ecology》2013,29(5):459-475
Eichhornia crassipes (Ec) and Lemna minor (Lm) are aquatic plants. They are considered as weeds of the water and approach being a scourge in many parts of the world, choking waterways and hindering transport upon them. At the same time they are known to readily remove heavy metal ions from water. This paper considers the use of non-living plants as novel and inexpensive biosorbent for the removal of As(V) from watersheds. In the first place they were conditioned and characterised to determine their physicochemical and surface properties and in the second place their adsorption properties for As(V) from aqueous solution were evaluated considering the toxicity of this metalloid in the environment. It describes the methodology to prepare the non-living biomasses; the physicochemical characterisation by SEM, XRD, FTIR, TGA analyses and surface characterisation of Ec and Lm by specific surface, hydration kinetic, point of zero charge determination by mass titration, active site density and XPS analysis are described. Both studied biomasses were found to be potential bio-sorbents for arsenic ions from aqueous solution. According to their efficiency to remove arsenic, they can be used in a very low cost metalloid ions removal system. 相似文献
908.
Danilo López-Hernández 《Chemistry and Ecology》2013,29(5):389-401
In 1970, a programme of land recuperation started in Venezuelan savannas, strongly affected by the seasonality of precipitation; therefore, a network of dykes has been built to alleviate the floods and retain water throughout the dry period. Under the dyked system, the environment has been altered, allowing a change in the herbaceous vegetation towards aquatic species and an increase in primary production. It is assumed that a considerable quantity of nutrients is lost from the ecosystem through the floodgates, a situation that could be worsened with the climate change. This contribution describes the atmospheric input and total output in stream run-off of phosphorous (P) in a flooded savanna. Internal pools of the biogeochemical cycle of P associated with terrestrial compartments are described. In the flooded savanna, a large amount of P is immobilised (29.6?kg?ha?1) in their above ground biomass by grasses, and in soil microbial biomass. The P budget was nearly balanced, as measured losses were cancelled out by the inputs in rainfall. Soils act as a sink, retaining P coming either from precipitation or from desorption/mineralisation processes. That interruption can be maximised, and losses of P and other nutrients can be minimised with an adequate management of the floodgate. 相似文献
909.
José L. Mateos Paloma Fernández Del Pino Francisco J. Gutiérrez Mañero María Ruiz Palomino Juan J. Colon José A. Lucas García 《Chemistry and Ecology》2013,29(2):125-152
Microbial communities (phospholipid fatty acid pattern, bacterial growing strategies, eco-physiological index (EPI) and total bacteria counts, as a number of heterotrophic cuhurable bacteria), substrate-induced respiration (SIR), and nitrogen mineralization were studied in three Mediterranean soils at three different depth levels (A, B and C). Soils were experimentally treated with a final concentration of 1000 ppm of trace metals (Cu2+, Zn2+, Al3+, Fe2+, Pb2+, Ni2+, Mn2+, Cr3+ and Cd2+). Soils were stored in 571 plastic containers for one year, and watered with 1001 during this period. Leachate was recovered through a bottom tap. Samples of the three depths were studied. Soil microbial communities showed different effects to other studies presented in the literature, but carried out on non-Mediterranean soils. Dramatic differences were found between treated soils and untreated ones, but not between soils or horizons. the treated soil displayed a decrease in CFUs, SIR N-mineralization and EPI together with a dominance of r-growing strategists. the relative moles percent of several PLFAs, especially 15:0, 16: 1ω7, cy17: 0, br18:0 and 18: 1ω7 decreased because of the pollution of soils, whereas 10Me16, 18:2ω6, cy19:0, i16:0 and br17:0 showed higher values than in untreated soils. 相似文献
910.
Copper, iron, lead, manganese, and zinc contents were determined in various phyla of macroalgae typical of the rocky mesolittoral zone of Cuba and widely distributed in the Caribbean Region. the samples were collected in different zones along the shores of Havana City which are more or less influenced by anthropogenic activities. Differences in metal contents were observed due to seasonal variations and differences between sampling sites. of the analyzed species, only one brown alga, Padina vickersiae is considered as a suitable candidate for the monitoring of metal contamination. 相似文献