全文获取类型
收费全文 | 357篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 9篇 |
废物处理 | 19篇 |
环保管理 | 61篇 |
综合类 | 61篇 |
基础理论 | 91篇 |
污染及防治 | 79篇 |
评价与监测 | 31篇 |
社会与环境 | 13篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 20篇 |
2015年 | 10篇 |
2014年 | 9篇 |
2013年 | 43篇 |
2012年 | 14篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1967年 | 4篇 |
1924年 | 1篇 |
排序方式: 共有369条查询结果,搜索用时 15 毫秒
51.
P. Hill C. Marshall H. Harmens D. L. Jones J. Farrar 《Water, Air, & Soil Pollution: Focus》2005,4(6):177-186
Soil respiration is a large C flux which is of primary importance in determining C sequestration. Here we ask how it is altered by atmospheric CO2 concentration and N additions. Swards of Lolium perenne L. were grown in a Eutric cambisol under controlled conditions with and without the addition of 200 kg NO? 3 ?N ha?1, at either 350 ppm or 700 ppm CO2, for 3 months. Soil respiration and net canopy photosynthesis were both increased by added N and elevated CO2, but soil respiration increased proportionately less than fixation by photosynthesis. Thus, both elevated CO2 and N appeared to increase potential C sequestration, although adding N at elevated CO2 reduced the C sequestered as a proportion of that fixed relative to elevated CO2 alone. Across all treatments below-ground respiratory C losses were predicted by root biomass, but not by soil solution C and N concentrations. Specific root-dependent respiration was increased by elevated CO2, such that below-ground respiration per unit biomass and per unit plant N was increased. 相似文献
52.
53.
54.
Vegetation: a sink for atmospheric pollutants 总被引:14,自引:0,他引:14
A C Hill 《Journal of the Air Pollution Control Association》1971,21(6):341-346
55.
56.
B. J. Hill 《Marine Biology》1976,34(2):109-116
The natural diet, rate of foregut clearance and diurnal activity of the crab Scylla serrata were determined. The gut volume is related to size of crab as gut volume (ml)=0.07e0.033x
, where x=carapace width in millimetres. Fifty per cent of crabs collected in Australia and South Africa contained molluscan remains and about 21% contained crustacean remains — chiefly grapsid crabs. Fish remains were rarely found, and it was concluded that S. serrata does not normally catch mobile forms such as fish and penaeid prawns. Gut clearance of organic tissue was rapid and almost complete after 12 h. Fish bone was retained for a mean time of 2 to 3 days, and shell for 5 to 6 days. Time-lapse photography, using infra-red light, was used to record activity. Visible light flashes reduced activity. S. serrata remained buried during the day, emerging at sunset to spend the night feeding, which occurred intermittently even when unlimited food was available. If no food was present the amount of time spent on the substrate surface was halved. 相似文献
57.
B. J. Hill 《Marine Biology》1975,32(2):119-126
Populations of the crab Scylla serrata (Forskal) were studied in two South African estuaries from 1971 until 1974. One estuary was open to the sea, the other was closed by a sandbar. Population density in the closed estuary was estimated by means of mark-release-recapture data from tagged crabs. The population of S. serrata was estimated as 1 crab/124m2 and the production at 3.4 g/m2/annum. Catch per unit effort data from the closed estuary indicated a natural mortality of 41% in the crabs' second year and 60% in the third. Growth was studied in both estuaries by means of size-frequency analysis and from tagging returns. Growth was rapid in the first 12 to 15 months, when the crabs attained a carapace width of 80 to 160 mm. Thereafter growth slowed, and after 3 years crabs were between 140 and 180 mm in carapace width. Females mated in summer at a carapace width of 103 to 148 mm, males at 141 to 166 mm. After mating, females migrated out of both estuaries into the sea. 相似文献
58.
Sexual selection and cuckoldry in a monogamous songbird: implications for sexual selection theory 总被引:11,自引:0,他引:11
Geoffrey E. Hill Robert Montgomerie Christina Roeder Peter Boag 《Behavioral ecology and sociobiology》1994,35(3):193-199
Sexual selection is generally assumed to be weaker in monogamous than in polygynous animals. Recently, though, extra-pair fertilizations have been hailed as an important force in generating variance in reproductive success among males in socially monogamous species, thereby increasing the intensity of sexual selection. To see if extra-pair copulations contribute to variance in male reproductive success in the house finch (Carpodacus mexicanus), we used DNA fingerprinting to determine the paternity of chicks from 35 nests. This species is a socially monogamous passerine in which plumage brightness serves as a sexually selected indicator of male quality. Out of 119, nestlings 10 (8.3%) were fathered by a male other than the attending male, but cuckoldry occurred randomly with respect to the plumage colouration, size, or age of the attending male. Thus extra-pair fertilizations do not generate variance in male reproductive success with respect to plumage colour. On the other hand, a strongly male-biased sex ratio and asynchronous breeding by females may generate substantial variance in male reproductive success and could explain the evolution of ornamental colouration. 相似文献
59.
A field and laboratory study in 1984–1985 using the foregut contents of crabs caught in Moreton Bay, Queensland, when trawling was underway, showed that animals discarded from trawls constituted about 33% of the diet. Portunus pelagicus can fill its foregut in about 8 min and clear it completely of tissues in about 6 h, except for fish bone which requires about 24 h. P. pelagicus used a zigzag search pattern to find food and moved towards it at a mean point-to-point speed of 290 m h-1 (8 cm s-1). Underwater still photography on the trawl grounds showed that P. pelagicus was the most common scavenger attracted to a bait that simulated trawl-discards, and that it was most active at dusk. Trawler-discards at periods of high food demand in summer may allow larger populations of P. pelagicus to exist than would otherwise occur. 相似文献
60.
Very low maternal serum alpha-fetoprotein (MSAFP) levels (<10 ng/mL) are known to be associated with non-viable pregnancies, including conditions such as fetal death, molar pregnancies, and non-pregnancies. There has not been agreement, however, as to whether very low MSAFP levels indicate already existing fetal deaths or are actually predictive. We analysed 230 pregnancies with MSAFP levels <10 ng/mL from among 15 807 women (1.5 per cent) screened consecutively during a three-year period and identified 26 non-viable pregnancies, 22 of which were diagnosed sonographically as part of the screening process (17 missed abortions, 3 blighted ova, 2 non-pregnancies). Furthermore, 20 of these 22 pregnancies were associated with essentially undetectable MSAFP levels (<5 ng/mL). Our data indicate that pregnancies with MSAFP values <5 ng/mL are the group most strongly associated with fetal non-viability and that very low MSAFP values are not strongly predictive for fetal death. 相似文献