全文获取类型
收费全文 | 2844篇 |
免费 | 2篇 |
国内免费 | 34篇 |
专业分类
安全科学 | 56篇 |
废物处理 | 140篇 |
环保管理 | 290篇 |
综合类 | 389篇 |
基础理论 | 1088篇 |
污染及防治 | 559篇 |
评价与监测 | 186篇 |
社会与环境 | 172篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 110篇 |
2017年 | 116篇 |
2016年 | 179篇 |
2015年 | 50篇 |
2014年 | 12篇 |
2013年 | 20篇 |
2012年 | 423篇 |
2011年 | 209篇 |
2010年 | 25篇 |
2009年 | 29篇 |
2008年 | 46篇 |
2007年 | 63篇 |
2006年 | 65篇 |
2005年 | 393篇 |
2004年 | 528篇 |
2003年 | 404篇 |
2002年 | 42篇 |
2001年 | 39篇 |
2000年 | 18篇 |
1999年 | 30篇 |
1998年 | 4篇 |
1997年 | 9篇 |
1996年 | 3篇 |
1995年 | 11篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有2880条查询结果,搜索用时 0 毫秒
221.
Alan?Rubelrstreiffer@wisc.edu" title="arubel@wisc.edu rstreiffer@wisc.edu" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Robert?Streiffer 《Journal of Agricultural and Environmental Ethics》2005,18(1):75-84
In her recent article, “Does autonomy count in favor of labeling genetically modified food?,” Kirsten Hansen argues that in Europe, voluntary negative labeling of non-GM foods respects consumer autonomy just as well as mandatory positive labeling of foods with GM content. She also argues that because negative labeling places labeling costs upon those consumers that want to know whether food is GM, negative labeling is better policy than positive labeling. In this paper, we argue that Hansen’s arguments are mistaken in several respects. Most importantly, she underestimates the demands of respecting autonomy and overestimates the cost of positive labeling. Moreover, she mistakenly implies that only a small minority of people desire information about GM content. We also explore the extent to which her arguments would apply to the US context, and argue that any discussion of the relationship between autonomy and labeling should include not just considerations of consumer autonomy but also considerations of what we call citizen autonomy. 相似文献
222.
Corinna?ThomEmail author David?C.?Gilley Jürgen?Tautz 《Behavioral ecology and sociobiology》2003,53(4):199-205
This study investigates the brief piping signals ("stop signals") of honey bee workers by exploring the context in which worker piping occurs and the identity and behavior of piping workers. Piping was stimulated reliably by promoting a colony's nectar foraging activity, demonstrating a causal connection between worker piping and nectar foraging. Comparison of the behavior of piping versus non-piping nectar foragers revealed many differences, e.g., piping nectar foragers spent more time in the hive, started to dance earlier, spent more time dancing, and spent less time on the dance floor. Most piping signals (approximately 99%) were produced by tremble dancers, yet not all (approximately 48%) tremble dancers piped, suggesting that the short piping signal and the tremble dance have related, but not identical, functions in the nectar foraging communication system. Our observations of the location and behavior of piping tremble dancers suggest that the brief piping signal may (1) retard recruitment to a low-quality food source, and (2) help to enhance the recruitment success of the tremble dance. 相似文献
223.
A method to estimate the impact of clear-cutting on nutrient concentrations in boreal headwater streams 总被引:1,自引:0,他引:1
Large-scale forestry operations, like clear-cutting, may impair surface water quality if not done with environmental considerations in mind. Catchment and country level estimates of nutrient loads from forestry are generally based on specific export values, i.e., changes in annual exports due to the implemented forestry operations expressed in kg ha−1. We introduce here a specific concentration approach as a method to estimate the impact of clear-cutting on nutrient concentrations and export in headwater streams. This new method is potentially a more dynamic and flexible tool to estimate nutrient loads caused by forestry, because variation in annual runoff can be taken into account in load assessments. We combined water quality data from eight boreal headwater catchment pairs located in Finland and Sweden, where the effect of clear-cutting on stream water quality has been studied experimentally. Statistically significant specific concentration values could be produced for total nitrogen, nitrate, ammonium, and phosphate. The significant increases in the concentrations of these nutrients occurred between 2 and 6 years after clear-cutting. Significant specific concentration values could not be produced for total phosphorus and total organic carbon with the whole dataset, although in some single studies significant increases in their concentrations after clear-cutting were observed. The presented method enables taking into account variation in runoff, temporal dynamics of effects, and the proportional size of the treated area in load calculations. The number of existing studies considering large site-specific variation in responses to clear-cutting is small, and therefore further empirical studies are needed to improve predictive capabilities of the specific concentration values. 相似文献
224.
225.
Virginia?Gonzalez-JimenaEmail author Patrick?S.?Fitze 《Behavioral ecology and sociobiology》2012,66(2):305-315
Glucocorticoids affect physiology and behaviour, reproduction and potentially sexual selection as well. Short-term and moderate
glucocorticoid elevations are suggested to be adaptive, and prolonged and high elevations may be extremely harmful. This suggests
that optimal reproductive strategies, and thus sexual selection, may be dose dependent. Here, we investigate effects of moderate
and high elevations of blood corticosterone levels on intra- and intersexual behaviour and mating success of male common lizards
Lacerta vivipara. Females showed less interest and more aggressive behaviour towards high corticosterone males and blood corticosterone levels
affected male reproductive strategy. Males of moderate and high corticosterone elevations, compared with Control males, showed
increased interest (i.e., higher number of chases, tongue extrusions, and approaches) towards females and high corticosterone
males initiated more copulation attempts. However, neither increased male interest nor increased copulation attempts resulted
in more copulations. This provides evidence for a best-of-a-bad-job strategy, where males with higher corticosterone levels
compensated for reduced female interest and increased aggressive female behaviour directed towards them, by showing higher
interest and by conducting more copulation attempts. Blood corticosterone levels affected intrasexual selection as well since
moderate corticosterone levels positively affected male dominance, but dominance did not affect mating success. These findings
underline the importance of female mate choice and are in line with adaptive compensatory behaviours of males. They further
show that glucocorticoid effects on behaviour are dose dependent and that they have important implications for sexual selection
and social interactions, and might potentially affect Darwinian fitness. 相似文献
226.
Marina?Della?Greca Maria?Rosaria?Iesce Lucio?PreviteraEmail author Maria?Rubino Fabio?Temussi 《Environmental Chemistry Letters》2004,2(3):155-158
The solar phototransformation of furosemide has been investigated in aqueous media. Irradiation of the drug in distilled water, in water and humic acids or nitrate ions, and in sewage sludge water affords a new dehalogenated dimer. The formation of the dimer has been explained by the formation of a cation radical intermediate. The low-measured environmental concentration of furosemide with respect to predicted environmental concentration in the Po and Lambro Rivers could be justified by its phototransformation. 相似文献
227.
Pei?Yang Zongbo?Li Yanqiong?Peng Darong?YangEmail author 《Die Naturwissenschaften》2012,99(3):199-205
In the obligate mutualism between figs (Ficus) and their specific pollinators (Chalcidoidea, Agaonidae), each species of fig wasp typically reproduces in figs of a single
host species. Host specificity is maintained largely because pollinators are attracted to tree-specific volatiles released
from their host figs, but whether the wasps can reproduce if they enter figs of non-host species is unclear. We investigated
the reproductive success of Ceratosolen emarginatus (associated with Ficus auriculata) and Ceratosolen sp. (associated with F. hainanensis) in atypical hosts by experimentally introducing foundresses into host and non-host figs. F. auriculata figs entered by Ceratosolen sp. were more likely to abort than if entered by C. emarginatus, but abortion of F. hainanensis figs was not affected by pollinator species. Single C. emarginatus foundresses produced more but smaller offspring in F. hainanensis than in their normal host. Conversely Ceratosolen sp. produced fewer but larger offspring in F. auriculata than in their normal host, probably as a result of having longer to develop. Mean style length differences, relative to the
lengths of the wasps’ ovipositors, may have dictated the number of offspring produced, with oviposition made easier by the
shorter styles in F. hainanensis figs. Our results imply that, in addition to morphological constraints and tree-specific volatiles, reduced reproductive
success in atypical hosts can be another factor maintaining host specificity, but for other species only behavioural changes
are required for host switching to occur. 相似文献
228.
Du?ica Ili? Ivan S. Risti? Ljubi?a Nikoli? Mihajlo Stankovi? Goran Nikoli? Ljiljana Stanojevi? Vesna Nikoli? 《Journal of Polymers and the Environment》2012,20(1):80-87
In this work was described poly(d,l-lactide) microwave synthesis using tin(II) 2-ethylhexanoate initiated ring-opening polymerization. Polymerization was performed
at 100 °C with monomer to initiator molar ratio ([M]/[I]) of 5,000 in 30 min. The achieved number average molar mass of obtained
polymers (determined by gel permeation chromatography) was 102,320 g/mol, with the polydispersion index, Q, 2.80. Structural characterization was performed by FT-IR spectroscopy followed characteristic bands. For applicative purposes
the obtained polymer was purified during the procedure of microsphere preparation. Biodegradable microspheres prepared from
poly(d,l-lactide) have been widely studied in recent years and have become well established controlled drug delivery systems. In this
work microspheres were loaded with allyl thiosulfinate (allicin) and its transforments products (ajoene and vinyldithiine),
as pharmacological active substances. The morphology of the microspheres was analyzed using a scanning electron microscope.
Allicin was synthesized by acid oxidation of allyl disufide and purification of obtained products by liquid–liquid extraction
with diethyl ether. Obtained allicin, purity 73%, was transformed using microwave in acetone solution, at solvent boiling
temperature, for 5 min. For the quality and quantity analysis of allicin and its transformation process was used LC/MS chromatography.
(E)- and (Z)-ajoene were detected at retention time 3.1 and 3.3 min, respectively, whence 3-vynil-4H-1,2-dithiine and 2-vynil-4H-1,3-dithiine
were detected at 4.3 and 4.8 min, respectively. Retention time of allicin was 2.93 min, according to liquid chromatography
results. HPLC method was used for assessment of pharmaceutical substances (alicine and alicine transforments) releasing from
microspheres at room temperature in solutions with different pH (pH = 3 and pH = 8) for 24 h. 相似文献
229.
The chemical signals of solitary and territorial felid species are essential for their intraspecific communication. We studied the selection of plant substrates during the fecal marking behavior of the European wildcat Felis silvestris from September 2008 to June 2009 in a protected area in Northwest Spain. The aim of the study was to examine the selection of plants as signal posts with respect to their physical characteristics. We hypothesized that wildcats deposit their fecal marks on plants with physical characteristics (e.g., size, species, and visual conspicuousness) that enhance the olfactory and visual effectiveness of the signal. Our results indicate that diameter, plant group, visual conspicuousness, and interaction between the diameter and plant group influence the decision of wildcats to deposit their fecal marks on plants. The wildcats chose plants with greater diameters and greater visual conspicuousness as scent-marking posts. Moreover, the wildcats chose woody and herbaceous plants, and certain plant species were marked more frequently than expected at random. Indeed, our results indicate that the fecal marks were not randomly distributed on the plants: the wildcats chose to place their marks on plants with certain physical characteristics that maximized the detectability of the signal by intruders and potential mates, thus facilitating the spatial distribution of the species. 相似文献
230.
Jeanger P Juanga Chettiyappen Visvanathan Josef Tr?nkler 《Waste management & research》2007,25(1):30-38
The optimization of anaerobic digestion aims to maximize organic waste stabilization after a short digestion period. This paper presents the optimization performance of the combined anaerobic digestion and sequential staging concept in a thermophilic, solid-state batch system as a treatment technology prior to landfill. The former involves enhanced pre-stage flushing with the addition of microaeration and inoculum in the methane phase. The latter involves leachate cross-recirculation between the mature and fresh waste reactors without conducting a pre-stage operation. The optimized process for combined anaerobic digestion showed that reducing the pre-stage operation with the maximum removal of organics from the waste bed is beneficial. Moreover, the sequential staging concept offers an improved process over the combined anaerobic digestion wherein the specific methane yield of 11.9 and 7.2 L CH4 kg(-1) volatile solids (VS) per day was achieved, respectively. After 28 days of operation, the sequential staging process showed an improved waste stabilization with 86 and 79% mass and volume reduction, respectively. A higher methane yield of 334 L CH4 kg(-1) VS with 86% VS reduction, which is equivalent to 84% process efficiency was obtained. 相似文献