全文获取类型
收费全文 | 2259篇 |
免费 | 18篇 |
国内免费 | 92篇 |
专业分类
安全科学 | 109篇 |
废物处理 | 213篇 |
环保管理 | 283篇 |
综合类 | 295篇 |
基础理论 | 392篇 |
环境理论 | 1篇 |
污染及防治 | 792篇 |
评价与监测 | 194篇 |
社会与环境 | 75篇 |
灾害及防治 | 15篇 |
出版年
2023年 | 11篇 |
2022年 | 34篇 |
2021年 | 36篇 |
2020年 | 12篇 |
2019年 | 41篇 |
2018年 | 73篇 |
2017年 | 58篇 |
2016年 | 78篇 |
2015年 | 54篇 |
2014年 | 67篇 |
2013年 | 184篇 |
2012年 | 124篇 |
2011年 | 145篇 |
2010年 | 96篇 |
2009年 | 130篇 |
2008年 | 135篇 |
2007年 | 147篇 |
2006年 | 128篇 |
2005年 | 115篇 |
2004年 | 106篇 |
2003年 | 97篇 |
2002年 | 88篇 |
2001年 | 62篇 |
2000年 | 37篇 |
1999年 | 24篇 |
1998年 | 20篇 |
1997年 | 23篇 |
1996年 | 16篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 19篇 |
1992年 | 10篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1978年 | 6篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1969年 | 5篇 |
排序方式: 共有2369条查询结果,搜索用时 15 毫秒
201.
202.
Ecological and physiological controls of species composition in green macroalgal blooms 总被引:9,自引:0,他引:9
Nelson TA Haberlin K Nelson AV Ribarich H Hotchkiss R Van Alstyne KL Buckingham L Simunds DJ Fredrickson K 《Ecology》2008,89(5):1287-1298
Green macroalgal blooms have substantially altered marine community structure and function, specifically by smothering seagrasses and other primary producers that are critical to commercial fisheries and by creating anoxic conditions in enclosed embayments. Bottom-up factors are viewed as the primary drivers of these blooms, but increasing attention has been paid to biotic controls of species composition. In Washington State, USA, blooms are often dominated by Ulva spp. intertidally and Ulvaria obscura subtidally. Factors that could cause this spatial difference were examined, including competition, grazer preferences, salinity, photoacclimation, nutrient requirements, and responses to nutrient enrichment. Ulva specimens grew faster than Ulvaria in intertidal chambers but not significantly faster in subtidal chambers. Ulva was better able to acclimate to a high-light environment and was more tolerant of low salinity than Ulvaria. Ulvaria had higher tissue N content, chlorophyll, chlorophyll b: chlorophyll a, and protein content than Ulva. These differences suggest that nitrogen availability could affect species composition. A suite of five grazers preferred Ulva to Ulvaria in choice experiments. Thus, bottom-up factors allow Ulva to dominate the intertidal zone while resistance to grazers appears to allow Ulvaria to dominate the subtidal zone. While ulvoid algae are in the same functional-form group, they are not functionally redundant. 相似文献
203.
Tae Won Lee Michael J. Miller Hak Bin Hwang Sam Wouthuyzen Katsumi Tsukamoto 《Marine Biology》2008,153(3):285-295
Leptocephali of the widely distributed tropical marine eels of the genus Kaupichthys (family Chlopsidae) were collected around Sulawesi Island during a sampling survey in the Indonesian Seas in late September
and early October 2002, and the otolith microstructure of 24 of the 59 specimens captured was examined to learn about the
larval growth rates and spawning times of these small sized eels. Leptocephali ranging in size from 25 to 60 mm were collected
in Makassar Strait and the Celebes Sea, but they were most abundant in the semi-enclosed Tomini Bay of northeast Sulawesi
Island. The Kaupichthys leptocephali examined had 39–161 otolith growth increments. Their back-calculated hatching dates indicated that five age
groups were present and each group appeared to have been spawned around the full moon of previous months. Average growth rate
estimates of the first two age groups were 0.65 and 0.54 mm/day for the 27.4–30.4 and 37.6–45.6 mm age classes. The growth
rates of the oldest three age groups (52.0–60.8 mm) appeared to have slowed down after they reached their approximate maximum
size. An increase in increment widths at the outer margin of the otoliths of those larger than 53 mm suggested that the process
of metamorphosis had begun even though there were few external morphological changes indicating metamorphosis. It is hypothesized
that chlopsid leptocephali have an unusually short gut that may not need to move forward during early metamorphosis. The presence
of four age classes in Tomini Bay suggests that the Togian Islands region may be productive habitats for Kaupichthys juveniles and adults. 相似文献
204.
Arsenic (As) contamination has become a serious environmental problem in many countries. We have performed batch-type leaching
experiments on mine tailing soils collected from three abandoned mine areas in South Korea with the objective of evaluating
the effect of indigenous bacterial activity on As mobilization. The analysis of physicochemical properties and mineralogical
compositions of the samples indicated that the secondary minerals or phases formed as a result of the oxidation or alteration
of primary minerals were associated with the labile and bioleachable fractions of As. Compared to simulated abiotic processes
using sterilization, the indigenous bacteria activated using a carbon source were able to enhance the dissolution of As under
both aerobic and anaerobic conditions. The bacterial dissolution of iron (Fe) and manganese (Mn) was found to occur simultaneously
with the dissolution of As, suggesting that the main bacterial mechanism was via the dissimilatory reduction of Fe(III),
Mn(IV), and As(V). An anaerobic environment was more favorable for the prominent dissolution of As in the tailing soils. These
results indicate that the mobilization of As can be enhanced in the oxygen-depleted part of the tailing dump, particularly
with the infiltration of organic substrates. The difference in the degree of As lixiviation between the three tailing soils
was found to be related to the bioavailability of As as well as the original biomass in the tailing soils. 相似文献
205.
Synchronous and intermittent reproduction in long-lived plants, known as mast seeding, is induced by climatic cues, but the mechanism explaining variation in masting among neighboring but edaphically segregated species is unknown. Soil nutrients can enhance flowering, and thus, populations on nutrient-rich soils may require less-favorable growing temperatures to flower. We tested this hypothesis by predicting the probability of flowering in response to air temperature for five species of alpine Chionochloa grasses in South Island, New Zealand, over 37 years and relating our predictions to soil N supply (NH4(+) + NO3(-)). Summer air temperatures better predicted flowering than spring air temperatures, which were correlated with soil N mineralization. Species on N-rich soils required lower mean temperatures to induce flowering and/or responded more consistently across a gradient of air temperatures, contributing to the higher probability of their tillers and tussocks flowering at low summer temperatures. Our results suggest that flowering primarily occurs in response to warm summer temperatures, but species on N-rich soils require less favorable growing conditions because they invest relatively less N in seeds. Thus, predicting masting requires a consideration of the interactions among climate, the internal resources of plants, and mineral nutrient uptake. 相似文献
206.
Kyung Min Lee Eun Chan Yang James A. Coyer Giuseppe C. Zuccarello Wei-Lui Wang Chang Geun Choi Sung Min Boo 《Marine Biology》2012,159(5):1021-1028
Although benthic marine algae are essential components of marine coastal systems that have been influenced profoundly by past and present climate change, our knowledge of seaweed phylogeography is limited. The brown alga Ishige okamurae Yendo occurs in the northwest Pacific, where it occupies a characteristic belt in the exposed intertidal zone. To understand the patterns of genetic diversity and the evolutionary history of this species, we analyzed mitochondrial cox3 from 14 populations (221 individuals) throughout its range. The 17 haplotypes found in this study formed five distinct clades, indicating significant genetic structure. The high differentiation and number of unique (private) haplotypes may result from the recolonization of the species from glacial refugia. Three putative refugia, each with high genetic diversity, were identified: southern Korea (including Jeju Island), northern Taiwan, and central Pacific Japan. Recolonization of I. okamurae was probably determined by ocean currents and changes in sea level during the last glacial period. 相似文献
207.
Yuchi Lee Shanglien Lo Jeff Kuo Chinghong Hsieh 《Frontiers of Environmental Science & Engineering》2012,6(1):17-25
Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate (S2O 8 2? ) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate the effects of pH (pH = 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01?C0.15 mol·L?1), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA degradation. When chloride concentrations were less than 0.04 mol·L?1 at 90°C and 0.06 mol·L?1 at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels, PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature. 相似文献
208.
Hea-Youn?Lee Hyo-Taek?ChonEmail author Manfred?Sager Laszlo?Marton 《Environmental geochemistry and health》2012,34(1):5-12
This study presents the level of platinum in urban environment in and around Seoul, the capital city of Korea. Road dust, roadside soil, and tree bark samples were collected from the sites of various traffic volumes and from control sites in the suburbs. The above samples were analyzed for Pt by ICP-MS and other heavy metals by ICP-OES. Platinum levels in road dusts and roadside soils from Seoul were in the range of 3.8–444 ng/g (av. 115.0 ng/g) and 0.7–221 ng/g (av. 49.7 ng/g), respectively, whereas those in the suburbs were in the range of 2.3–5.2 ng/g (av. 3.9 ng/g) in road dusts and 0.4–5.1 ng/g (av. 2.4 ng/g) in roadside soils. The highest Pt levels in road dusts were found from major roads with high traffic volume. The remarkable difference in average Pt level between heavy traffic roads (av. 132.2 ng/g) and light traffic roads (av. 22.8 ng/g) reflects that an important source of Pt in roadside environment is automobile catalytic converter. High Pt level in road dust was found from the site of erratic stop–start driving condition, for example, 178 ng/g Pt in road dust around a vehicle crossing gate. Platinum level in tree barks ranged from 0.9 to 4.5 ng/g, which indicates the existence of Pt-containing particulate matter in the atmosphere. Road dusts with high Pt level were enriched in traffic-related heavy metals. 相似文献
209.
Larisa Lee Cruz Rona A. R. McGill Simon J. Goodman Keith C. Hamer 《Marine Biology》2012,159(4):873-880
Stable isotope analysis of carbon and nitrogen is frequently used to study the diets and foraging ecology of marine predators.
However, isotopic values may also be affected by an individual’s nutritional status and associated physiological processes.
Here, we use C and N stable isotopes in blood and feathers of blue-footed booby chicks at the Galápagos Islands to examine
how isotopic values are related to body condition and growth rate, and to assess the consistency in the isotope ratios of
individuals during growth. Size dimorphism in blue-footed boobies provided an additional opportunity to examine how isotope
ratios differ between sexes in relation to body size and growth rate. There was no significant difference between sexes but
both C and N stable isotopes were significantly negatively related to the body condition of chicks. These data were consistent
with individual variation in physiological processes affecting fractionation, although we cannot rule out the possibility
that they were also influenced to some extent by population-level variation in the stable isotope ratios of prey fed to chicks,
for instance related to prey size, depth or lipid content. Our results highlight the need for methods that take proper account
of confounding physiological factors in isotopic studies of foraging ecology and diet. 相似文献
210.
The toxic effects of the composites of Fe~0 and Cu~0 with different percentages of CNTs were examined based on the activity of bacterial bioluminescence and seed germination. In terms of the EC_50 values, the toxic effects of Cu~0 on bacterial bioluminescence and seed germination were approximately 2 and 180 times greater than that of Fe~0, respectively. The toxicity increased with increasing CNT content in the Cu-CNT mixtures for both organisms,whereas opposite results were observed with Fe-CNT mixtures. The mean toxic effects of Cu-CNT(6%) were approximately 1.3–1.4 times greater than that of Cu-CNT(0%), whereas the toxic effects of Fe-CNT(6%) were approximately 2.1–2.5 times lower than that of Fe-CNT(0%) for both the bioluminescence activity and seed germination. The causes of this phenomenon are unclear at this point. More research will be needed to elucidate the mechanism of the toxicity of nano-mixture materials and the causes of the different patterns of toxicity with Cu-and Fe-CNT mixtures. 相似文献