全文获取类型
收费全文 | 452篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 30篇 |
废物处理 | 16篇 |
环保管理 | 125篇 |
综合类 | 53篇 |
基础理论 | 87篇 |
环境理论 | 2篇 |
污染及防治 | 92篇 |
评价与监测 | 37篇 |
社会与环境 | 14篇 |
灾害及防治 | 2篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2019年 | 3篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 40篇 |
2012年 | 14篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 19篇 |
2007年 | 19篇 |
2006年 | 8篇 |
2005年 | 17篇 |
2004年 | 7篇 |
2003年 | 14篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1967年 | 2篇 |
1963年 | 2篇 |
1962年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有458条查询结果,搜索用时 156 毫秒
101.
102.
Neely Law Lawrence Band Morgan Grove 《Journal of Environmental Planning and Management》2004,47(5):737-755
A residential lawn care survey was conducted as part of the Baltimore Ecosystem Study, a Long-term Ecological Research project funded by the National Science Foundation and collaborating agencies, to estimate the nitrogen input to urban watersheds from lawn care practices. The variability in the fertilizer N application rates and the factors affecting the application rates were examined. Results indicated that the annual input of nitrogen from fertilizer is a major component of the urban watershed nitrogen budget and it is both spatially and temporally variable. There is a wide range in the application rate of fertilizer N to residential lawns applied by homeowners and by professional lawn care companies. Survey data estimated a mean fertilizer application rate of 97.6 kg N/ha/yr with a standard deviation of 88.3 kg N/ha/yr. Analyses suggested that the fertilizer application rate is affected by social economic factors and soil characteristics to include the market value of the house, age of development, soil bulk density and soil nitrogen content. 相似文献
103.
104.
A. Ann Sorensen Tana M. Busch S. Bradleigh Vinson 《Behavioral ecology and sociobiology》1985,17(3):191-198
Summary Temporal subcastes in the fire ant, Solenopsis invicta Buren were selectively starved to determine if foragers could assess the nutritional status of their nestmates and respond accordingly. We found that starved foragers increase the honey entering the colony (Fig. 1). When nurses are starved more oil and liquid egg yolk enters the colony (Figs. 2, 3) and when both reserves and nurses are starved, more egg yolk powder is brought in by the foragers (Fig. 4). When queens are starved, more liquid egg yolk and oil enters the colony (Figs. 2, 3). Starved larvae increase the oil in the colony (Fig. 2) and when held with nurses for 24h before feeding, increase the egg yolk powder brought in and receive significantly more of it than other subcaste members (Fig. 5). We conclude that foragers can respond to the nutritional needs of their nestmates. Based on our behavioural observations, the quantity of food brought in by the foragers is regulated via discriminatory solicitation by reserves in response to the nutritional needs of the nurses. 相似文献
105.
Social insect colonies respond to challenges set by a variable environment by reallocating work among colony members. In many social insects, such colony-level task allocation strategies are achieved through individual decisions that produce a self-organized adapting group. We investigated colony responses to parasitoids and native ant competitors in the red imported fire ant (Solenopsis invicta). Parasitoid flies affected fire ants by decreasing the proportion of workers engaged in foraging. Competitors also altered colony-level behaviours by reducing the proportion of foraging ants and by increasing the proportion of roaming majors, whose role is colony defence. Interestingly, the presence of both parasitism and competition almost always had similar effects on task allocation in comparison to each of the biotic factors on its own. Thus, our study uniquely demonstrates that the interactive effect of both parasitism and competition is not necessarily additive, implying that these biotic factors alter colony behaviour in distinct ways. More generally, our work demonstrates the importance of studying the dynamics of species interactions in a broader context. 相似文献
106.
107.
Lillian Y. F. Hsu MD Sara Kaffe Edmund C. Jenkins Lita Alonso Peter A. Benn Karen David Kurt Hirschhorn Ernest Lieber Alan Shanske Lawrence R. Shapiro Edward Schutta Dorothy Warburton 《黑龙江环境通报》1992,12(7):555-573
Currently, accepted protocol which has been developed at the Prenatal Diagnosis Laboratory of New York City (PDL) requires that when a chromosome abnormality is found in one or more cells in one flask, another 20–40 cells must be examined from one or two additional flasks. Chromosome mosaicism is diagnosed only when an identical abnormality is detected in cells from two or more flasks. In a recent PDL series of 12 000 cases studied according to this protocol, we diagnosed 801 cases (6.68 per cent) of single-cell pseudomosaicism (SCPM), 126 cases (1.05 per cent) of multiple-cell pseudomosaicism (MCPM), and 24 cases (0.2 per cent) of true mosaicism. Pseudomosaicism (PM) involving a structural abnormality was a frequent finding (2/3 of SCPM and 3/5 of MCPM), with an unbalanced structural abnormality in 55 per cent of SCPM and 24 per cent of MCPM. We also reviewed all true mosaic cases (a total of 50) diagnosed in the first 22000 PDL cases. Of these 50 cases, 23 were sex chromosome mosaics and 27 had autosomal mosaicism; 48 cases had numerical abnormalities and two had structural abnormalities. Twenty-five cases of mosaicism were diagnosed in the first 20 cells from two flasks, i.e., without additional work-up, whereas the other 25 cases required extensive work-up to establish a diagnosis (12 needed additional cell counts from the initial two culture flasks; 13 required harvesting a third flask for cell analysis). Our data plus review of other available data led us to conclude that rigorous efforts to diagnose true mosaicism have little impact in many instances, and therefore are not cost-effective. On the basis of all available data, a work-up for potential mosaicism involving a sex chromosome aneuploidy or structural abnormality should have less priority than a work-up for a common viable autosomal trisomy. We recommend revised guidelines for dealing with (1) a numerical versus a structural abnormality and (2) an autosomal versus a sex chromosome numerical aneuploidy. Emphasis should be placed on autosomes known to be associated with phenotypic abnormalities. These new guidelines, which cover both flask and in situ methods, should result in more effective prenatal cytogenetic diagnosis and reduced patient anxiety. 相似文献
108.
Michael R. Heithaus Aaron J. Wirsing Lawrence M. Dill Linda I. Heithaus 《Marine Biology》2007,151(4):1455-1461
Tiger sharks are important predators in the seagrass ecosystem of Shark Bay, Australia. Although sharks appear to return to
a long-term study site within the Eastern Gulf periodically, the extent of their long-term movements is not known. Five sharks
fitted with satellite transmitters showed variable movement patterns. Three sharks remained within the Shark Bay region and
another made a 500 km round-trip excursion to oceanic waters northwest of the bay. These four sharks showed relatively low
displacement rates relative to sharks tracked over shorter time periods, suggesting that sharks move through large home ranges
that include Shark Bay. Although no reliable position fixes were obtained for the fifth shark, we were able to use the timing
of satellite uplinks and the position of the satellite to determine that it had moved at least 8,000 km to the coastal waters
of southeast Africa in 99 days—the longest recorded movement by a tiger shark. This movement and previously documented trans-Atlantic
movements suggest that tiger shark populations may mix across ocean basins and that tiger sharks are subject to anthropogenic
effects at great distances from protected waters. Finally, our method for using single satellite uplinks may be useful in
estimating movements for wide-ranging species that rarely provide high quality location estimates. 相似文献
109.
The benzene and toluene levels inside three homes with attached garages were measured for 12 consecutive weeks during the winter months in Fairbanks, Alaska (Latitude 64.5 degrees N). Results for air samples collected over 12 h for the homes showed indoor benzene mixing ratios ranging from 1.6 to 20.4 parts per billion of mixing ratio volume (ppbv), and toluene air mixing ratios ranging from 7.3 to 41.6 ppbv. A correlation between benzene and toluene levels in each home and similar regression lines suggested the same major emission source, car and small equipment gasoline, present in attached garages. In one home, there was a correlation between indoor benzene mixing ratios and the urinary biomarker, trans,trans-muconic acid. Inside, air mixing ratios of benzene and toluene decreased with decreasing outside temperature in all homes studied, even though homes were relatively tight to prevent heat loss during this period of low winter outdoor temperatures. It is suggested that buildup of these pollutants indoors is prevented by the influence of an increased indoor/outdoor temperature differential and an ensuing increase in home ventilation. 相似文献
110.
Minimal transmission of zearalenone to milk of dairy cows 总被引:2,自引:0,他引:2
D B Prelusky P M Scott H L Trenholm G A Lawrence 《Journal of environmental science and health. Part. B》1990,25(1):87-103
Milk and plasma levels of zearalenone (ZEN), alpha-zearalenol (alpha-ZEL), beta-zearalenol (beta-ZEL) and conjugated metabolites were determined after feeding lactating cows with ZEN. In those instances where ZEN and alpha- and beta-ZEL were detected in milk or plasma, they occurred only as conjugates hydrolysable by treatment with a mixture of beta-glucuronidase and aryl sulfatase. With studies where 50 or 165 mg was fed daily to three cows for 21 day periods, neither dosage showed the presence of ZEN or metabolites in either milk or plasma (detection limits: milk, 0.5 ng/ml, ZEN, alpha-ZEL; 1.5 ng/ml, beta-ZEL; plasma, 2-3 times higher). A dose of 544.5 mg zearalenone per day given to a single cow for 21 days yielded maximum concentrations of only 2.5 ng ZEN/ml and 3.0 ng alpha-ZEL/ml in the milk. In plasma, up to 3 ng ZEN/ml could be detected during the initial 4 days of treatment. At a dose of 1.8 g of zearalenone given over a one day feeding period, maximum milk levels of 4.0 ng ZEN/ml, 1.5 ng alpha-ZEL/ml, and 4.1 ng beta-ZEL/ml were observed during the initial 2 days; corresponding maximum levels after a one day dose of 6.0 g zearalenone were 6.1, 4.0 and 6.6 ng/ml milk on days 2-3. In plasma, peak ZEN concentrations (9 and 13 ng/ml at the lower and higher one-day doses, respectively) occurred 12 hr after initial dosing, and declined to negligible levels by days 5-7. Neither alpha- nor beta-ZEL were detected in plasma. Since measurable levels required very high oral doses of ZEN, milk would not normally pose a human health hazard as a result of feeding rations containing ZEN to lactating dairy cows. 相似文献