全文获取类型
收费全文 | 6099篇 |
免费 | 50篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 122篇 |
废物处理 | 368篇 |
环保管理 | 491篇 |
综合类 | 732篇 |
基础理论 | 1354篇 |
环境理论 | 7篇 |
污染及防治 | 2132篇 |
评价与监测 | 540篇 |
社会与环境 | 422篇 |
灾害及防治 | 17篇 |
出版年
2023年 | 67篇 |
2022年 | 182篇 |
2021年 | 204篇 |
2020年 | 88篇 |
2019年 | 98篇 |
2018年 | 253篇 |
2017年 | 232篇 |
2016年 | 325篇 |
2015年 | 181篇 |
2014年 | 323篇 |
2013年 | 529篇 |
2012年 | 379篇 |
2011年 | 451篇 |
2010年 | 305篇 |
2009年 | 255篇 |
2008年 | 346篇 |
2007年 | 373篇 |
2006年 | 279篇 |
2005年 | 228篇 |
2004年 | 191篇 |
2003年 | 149篇 |
2002年 | 133篇 |
2001年 | 106篇 |
2000年 | 77篇 |
1999年 | 48篇 |
1998年 | 28篇 |
1997年 | 24篇 |
1996年 | 16篇 |
1995年 | 33篇 |
1994年 | 27篇 |
1993年 | 17篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 14篇 |
1985年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 4篇 |
1967年 | 5篇 |
1966年 | 7篇 |
1965年 | 7篇 |
1964年 | 12篇 |
1962年 | 7篇 |
1961年 | 5篇 |
1960年 | 5篇 |
1959年 | 8篇 |
1958年 | 18篇 |
1957年 | 8篇 |
排序方式: 共有6185条查询结果,搜索用时 15 毫秒
301.
To restore food security to a traditional African cropping system following a sudden loss of seed, genetic diversity must be re-established. This study examines the extent to which Cowpea diversity was reinstated two years after a flood disaster in Gaza Province, Mozambique. The contribution that seed from various sources made to the recovery was assessed using semi-structured interviews and morphological and molecular data. Data suggest that diversity had recovered to some extent yet there was evidence of a narrowing of the genetic base, with fewer rare alleles and differences in the distribution of allele frequencies. Although the main channels for accessing seed after the flood were seed relief and markets, these sources contributed to minimal and different diversity. It appears that diversity was regained primarily through social networking in the form of loans or gifts of seed from friends and relatives. The results of the study are discussed in relation to seed relief approaches. 相似文献
302.
Baeza A Vallejo I Guillén J Salas A Corbacho JA 《Journal of environmental radioactivity》2011,102(3):311-315
Adequate radioprotection of the environment requires the identification of biomonitors sensitive to the variation of its radionuclide content. Due to the chemical similarities between calcium and strontium, calcified tissues of mammals are considered to be good 90Sr biomonitors. This work considered Cervus elaphus antlers which, being shed annually, can give information about the importance of radiostrontium contamination in an ecosystem in the time period required for the growth of the antler. The samples were collected at various points of W and SW Spain. The mean value of their 90Sr content was (70 ± 43 (S.D.)) Bq/kg d.w., range (16-218) Bq/kg d.w., and the radionuclide was evenly distributed in the different parts of the antler. There was a good correlation between the antlers’ 90Sr content and the 90Sr deposited in the soil. The antlers’ content of 226Ra (from the natural uranium series) and the contents of some stable elements (Ca, Mg, Sr, and K) were also determined. The values for these stable elements were practically constant in the analyzed samples, and the concentrations measured decreased in the following order:Ca » Mg > K > Sr » 90Sr > 226Ra 相似文献
303.
A biomonitoring survey using the moss species Hypnum cupressiforme Hedw. was conducted in the surroundings of two steel plants located in the North of Spain. Levels of V, Cr, Ni, Cu, Zn, As, Cd, Hg, Pb and N were determined. Very high concentrations in the areas of study were detected when compared to nearby unaffected regions. Similar trends were observed for all the elements in the differently orientated transects, showing an appreciable influence of the NW prevailing winds of the region in the dispersion of pollutants, as well as a clear decreasing gradient in the concentrations of metals in mosses within a distance of 1500 meters from the facilities. A differentiation between the elements emitted by the chimney as result of the industrial activity (V, Cr, Ni, Cu and As) and those with a high presence in steel slag deposits (Zn, Cd, Hg and Pb) was observed. The range of contamination was also established by means of the Contamination Factor, indicating a category 4 out of 6 categories, which shows the high levels reported in the areas of study. A different dynamic was registered for nitrogen regarding the rest of the heavy metals analysed except for Hg, probably due to the elevated volatility and mobility of both elements, as well as their high persistence in the atmosphere. 相似文献
304.
305.
Eu Gene Chung Fabián A. Bombardelli S. Geoffrey Schladow 《Ecological modelling》2009,220(9-10):1251-1265
The interactions between bed sediments and the water column in shallow, eutrophic lakes have tremendous implications for the fate and transport of nutrients in those water bodies. This has resulted in the development of water quality models for lakes incorporating the processes of sediment resuspension. Reliable resuspension models are thus needed to accurately represent this phenomenon. In this paper, three different sediment-resuspension models are combined with a hydrodynamic and water quality model, dynamic lake model-water quality (DLM-WQ), and the resulting models are used to simulate nutrient distributions in the highly eutrophic Salton Sea, California, USA. One of the resuspension formulas is based upon sediment characteristics as well as the bed shear stress exerted by wind-induced waves and currents, while the other two are standard, power-law-type formulas for cohesive sediments with two different exponents. The outputs for water quality variables, such as temperature, chlorophyll a, dissolved oxygen and nutrients, obtained from the three resulting models and from an earlier DLM-WQ run with a simple empirical sediment-resuspension model are compared with measured data. The level of agreement between the simulations and the measured data is assessed by using both statistical and graphical model evaluation methods, including measures of residual errors, sample autocorrelations, t-tests, and box plots. Based on these assessments, DLM-WQ with an extended version of the García and Parker [García, M.H., Parker, G., 1993. Experiments on the entrainment of sediment into suspension by a dense bottom current. J. Geophys. Res.-Oceans 98, 4793–4807] relationship gave the best results for water quality in the Salton Sea, confirming that the use of formulas with more information on the sediment characteristics yields more accurate results. To the best of our knowledge, this is the first effort to combine water quality models for lakes and reservoirs with a sediment-resuspension model which was originally intended for open-channel flows. The simulations confirm that sediment resuspension is the most dominant process in the Salton Sea's nutrient cycling. The effect of proposed physical changes to the Salton Sea on water quality characteristics is also addressed. 相似文献
306.
Ali Jamshidparvar Faramin Javandel Alireza Seidavi Francisco Peña Blanco Andrés L. Martínez Marín Carmen Avilés Ramírez Estrella Agüera Buendía Nieves Núñez-Sánchez 《Environmental science and pollution research international》2017,24(30):23571-23577
Increasing levels of Heracleum persicum (golpar) in drinking water were studied in broilers. Two hundred and forty-one-day-old male chickens were allocated to one of six treatments: control, without added phytogenics nor probiotics in drinking water, and probiotics at recommended manufacturer’s level (P) or 1.0, 1.5, 2.0, and 2.5 ml/l of golpar extract solution (G1, G1.5, G2, and G2.5 treatments, respectively) in drinking water. As a result of this study, no linear or quadratic trends in the feed intake (FI) and feed conversion rate (FCR) due to golpar supplementation were found. Body weight gain, final body weight, and relative carcass weight showed a positive linear response with increasing levels of golpar supplementation. Neither golpar nor probiotics had effects on the percentages of edible parts of the carcass. Golpar supplementation levels caused a linear negative response of the albumin content in blood plasma, whereas both abdominal fat as percentage of carcass weight and uric acid levels in blood plasma linearly increased. The effects on Ig responses were only observed at 42 days of age and were similar in probiotics and the highest level of golpar supplementation. Based on our results, both probiotics and golpar supplementation could improve broiler performance and immune function. 相似文献
307.
308.
María del Mar Delgado Vincenzo Penteriani Vilis O. Nams Letizia Campioni 《Behavioral ecology and sociobiology》2009,64(1):35-43
Moving and spatial learning are two intertwined processes: (a) changes in movement behavior determine the learning of the
spatial environment, and (b) information plays a crucial role in several animal decision-making processes like movement decisions.
A useful way to explore the interactions between movement decisions and learning of the spatial environment is by comparing
individual behaviors during the different phases of natal dispersal (when individuals move across more or less unknown habitats)
with movements and choices of breeders (who repeatedly move within fixed home ranges), that is, by comparing behaviors between
individuals who are still acquiring information vs. individuals with a more complete knowledge of their surroundings. When
analyzing movement patterns of eagle owls, Bubo bubo, belonging to three status classes (floaters wandering across unknown environments, floaters already settled in temporary
settlement areas, and territory owners with a well-established home range), we found that: (1) wandering individuals move
faster than when established in a more stable or fixed settlement area, traveling larger and straighter paths with longer
move steps; and (2) when floaters settle in a permanent area, then they show movement behavior similar to territory owners.
Thus, movement patterns show a transition from exploratory strategies, when animals have incomplete environmental information,
to a more familiar way to exploit their activity areas as they get to know the environment better. 相似文献
309.
Germán Arana-Landin Iñaki Heras-Saizarbitoria 《Journal of Cleaner Production》2011,19(9-10):1007-1015
A Spanish ecodesign standard (the UNE 150301) is being used as a basic reference point in paving the way for the future ISO 14006 ecodesign standard which may foreseeably be passed in 2011. This article aims to analyze the experience regarding adoption of the UNE 150301 in Spain.Following an analysis of the standard’s structure, its objectives and scope, its real implementation process is then analyzed based on an exploratory qualitative study carried out in four Spanish companies that have been pioneers in adopting this environmental standard. The conclusion is drawn in the article that in all the cases analyzed, the greatest source of impact occurs in the phase in which the product is used and is related to energy consumption. Companies appear to be satisfied with the adoption of this standard and, in particular, point out that they have managed to reduce the environmental impact of their products. However, they draw attention to the fact that, to deal with certain instances of impact that increases in cost entail, administrative bodies need to establish mandatory regulations, as environmentally-friendly companies would otherwise lose competitiveness. 相似文献
310.
Teresa Moreno Marco Pandolfi Xavier Querol Javier Lavín Andrés Alastuey Mar Viana Wes Gibbons 《Environmental science and pollution research international》2011,18(2):173-183