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281.
This study aimed to gain insight on patterns of spatial variability of seagrass epiphytes of both leaves and of rhizomes in
three different habitats, continental coasts, offshore banks and islands. Moreover, we tried to discriminate between habitat-dependant
variability and scale-dependant variability of Posidonia oceanica epiphytic assemblages. Results showed the absence of significant differences in the structure of assemblages of epiphytes
both on leaves and on rhizomes among continental coasts, offshore banks and islands, even if the patterns of spatial variability
changed among habitats. In fact, although a high variability at small scales appeared a constant pattern in epiphytic assemblages,
large-scale variability resulted higher in continental coasts and offshore banks than in islands. In conclusion, epiphytic
assemblages of Posidonia oceanica appear homogeneous among habitats, showing a similar structure and species composition in the same geographic area. On the
contrary, differences between meadows appeared linked to local differences in environmental factors that are more evident
in habitats influenced by human disturbance.
An erratum to this article can be found at 相似文献
282.
Screening of POP pollution by AChE and EROD activities in Zebra mussels from the Italian Great Lakes
The increase of ethoxyresorufin dealkylation (EROD) and the inhibition of acetylcholinesterase (AChE) as biomarkers have been commonly used in vertebrates for the persistent organic pollutants (POPs) biomonitoring of aquatic environments, but very few studies have been performed for invertebrates. Previous researches demonstrated the interference due to some chemicals on EROD and AChE activities of the freshwater bivalve Zebra mussel (Dreissena polymorpha) in laboratory and field studies, showing its possible use for the screening of POP effects. We investigated the contamination of the Italian sub-alpine great lakes (Maggiore, Lugano, Como, Iseo, Garda) by the biomarker approach on Zebra mussel specimens collected at 17 sampling sites with different morphometric characteristics and anthropization levels. Results showed a homogeneous contamination of AChE inhibitors in Lake Garda, Maggiore, Como and Iseo with values ranging from 0.5 to 3 nmol/min/mg proteins and with an average inhibition of about 66% to controls. The planar compounds pollution, able to activate the EROD activity, seems higher in some sampling stations of Lake Garda, Como and Iseo (2-4 pmol/min/mg proteins) than that measured in Lake Lugano (1.5-3 pmol/min/mg proteins). On the contrary, the enzyme activity in Lake Maggiore showed an interesting opposite effect of AhR-binding compounds and trace metals. Finally, the possible use of Zebra mussel specimens maintained at laboratory conditions as controls against the selection of the less polluted sampling site is discussed. 相似文献
283.
Stefano Goffredo Erik Caroselli Elettra Pignotti Guido Mattioli Francesco Zaccanti 《Marine Biology》2007,152(2):351-361
The correlation between two environmental factors (solar radiation and sea surface temperature), biometry, and population
density was assessed along a latitudinal gradient in the zooxanthellate coral Balanophyllia europaea and in the azooxanthellate coral Leptopsammia pruvoti. With increasing polyp size, the oral disc of B. europaea assumed an oval shape, while that of L. pruvoti retained a circular shape. In both species, biometric parameters varied more with temperature than with solar radiation.
In the zooxanthellate species, temperature explained a higher percentage of biometric parameter variance than in the azooxanthellate
species. While environmental factors did not co-vary with demographic characteristics in L. pruvoti, temperature was negatively related to the population density of B. europaea. It is hypothesized that the negative effect of temperature on biometry and population density of B. europaea depends on photosynthesis inhibition of symbiotic zooxanthellae at high temperatures, which would lower the calcification
rate and availability of energetic resources. 相似文献
284.
Humans show intra- and intersexual variation in second (2D) relative to fourth (4D) finger length, men having smaller 2D:4D ratio, possibly because of differential exposure to sex hormones during fetal life. The relations between 2D:4D and phenotypic traits including fitness components reported by several studies may originate from the organizational effects that sex hormones have on diverse organs and their concomitant effect on 2D:4D. Evolutionary theory posits that sexual preferences are adaptations whereby choosy individuals obtain direct or genetic indirect benefits by choosing a particular mate. Since sex hormones influence both fitness and 2D:4D, hand sexual attractiveness should depend on 2D:4D, a hypothesis tested only in one correlational study so far. We first presented hand computer images to undergraduates and found that opposite-sex hands with long 2D and 4D were considered more sexually attractive. When we experimentally manipulated hand images by increasing or decreasing 2D and/or 4D length, women preferred opposite-sex hands that had been masculinized by elongating 4D, whereas men avoided masculinized opposite-sex right hands with shortened 2D. Hence, consensus exists about which hands are attractive among different opposite-sex judges. Finger length may signal desirable sex hormone-dependent traits or genetic quality of potential mates. Psychological mechanisms mediating hand attractiveness judgments may thus reflect adaptations functioning to provide direct or indirect benefits to choosy individuals. Because the genetic mechanisms that link digit development to sex hormones may be mediated by Hox genes which are conserved in vertebrates, present results have broad implications for sexual selection studies also in nonhuman taxa. 相似文献
285.
Francesco Lucarelli Paolo De Stefano Luigi G. Napolitano Pasquale Murino Rosario Vigliotti 《Environmental management》1994,18(4):597-604
After a critical analysis of the strategies for conservation of the environment in Latin America and of large-scale development
projects (agriculture and livestock raising, mining and electrical power plants) in the Amazon region of Brazil, this paper
deals with the use of high-resolution satellite imagery for environmental monitoring. Two areas were considered in the study,
Tucurui and Altamira. Spot/XS and Landsat/TM multispectral images were used, together with color aerial photographs of these
areas. A computer-assisted visual interpretation procedure was employed to analyze images, and linear multispectral transformation
was applied in selected subscenes in order to improve information extraction. The results indicate that high-resolution satellite
imagery is generally compatible with the scale of the environmental problems in Amazonia and is a very efficient source of
detailed information at a local scale on many aspects of the environment, in particular for monitoring changes over time in
selected areas. Therefore, commercial satellite imagery, processed by specialized software, can accommodate a variety of analysis
needs for decision makers and can also be an effective means of verification of international agreements on conservation of
the environment in Amazonia. 相似文献
286.
Marco Ferretti Emilia Barbolani Paolo Grossoni Romano Gellini Francesco Pantani 《Chemistry and Ecology》1993,8(1):1-10
One year old needles of both healthy and damaged silver fir and Norway spruce from the area of Trento (Northern Italy) were observed by SEM. Needles of damaged trees show quite evident structural alterations of epidermis, expecially epicuticular waxes. Roots and needles of both fir and spruce are also tested for their metal content. Evidence is reported of an increasing concentration of Fe, Mg and Ca in roots of plants grown on alkali soil. Ca, and to a lesser extent Fe, Al and Pb, appears to be more present in old needles, whereas K and Mg exhibit higher amounts in young needles. Some indications are found between damage and the content of some metals such as Mg and Mn in needles. 相似文献
287.
288.
Francesco Frangialli 《生态毒理学报》2002,24(3):4
国际生态旅游年表明联合国认识到了生态旅游在社会和经济方面的重要性 . 联合国大会希望 让政府和国际社会注意到生态旅游对自然环境、生物多样性保护以及当地的社会和文化结构 的潜在影响 ( 正面的和负面的 ) . 世界旅游组织 ( WTO) 正在和联合国环境署 ( UNEP) 、其他 国际机构和地区机构及其成员国、会员和其他团体一起协调一系列活动 - - 作为国际生态旅 游年 ( IYE) 的准备以及在国际生态旅游年期间的活动 . 相似文献
289.
The relevance of the integration of preimaginal and eclosion experiences on the subsequent habitat preferences and mate finding
by the adult has been rarely tested in holometabolous insects. In this work, the effect of larval and early adult experiences
on the behavioural responses of adult males of the aphid parasitoid, Aphidius ervi, towards volatiles from the host–plant complex (HPC) and from conspecific females were evaluated. Two experience factors
were considered: host diet (normal diet=ND; artificial diet=AD), and eclosion, i.e. extraction or non-extraction of the parasitoid
larva from the parasitised aphid (extracted=EX; non-extracted=NE). Thus, four treatments were set up: ND/NE, ND/EX, AD/NE
and AD/EX. Glass Y-tube olfactometers were used to investigate the responses of adult A. ervi males to the odour sources used. Males from the ND/NE treatment showed a shorter latency to the first choice of olfactometer
arms, displayed a marked preference towards the HPC olfactometer arm, and spent more time in the HPC arm than males from the
other treatments. Only the interaction of host diet and eclosion experiences proved to be relevant in explaining the differences
in latency to first choice, time spent in olfactometers arms, and behaviours displayed in the olfactometer arms. These results
show the importance of the integration of larval and eclosion experiences in the development of stereotyped responses of the
adults. This process may involve memory retention from the preimaginal and emergence period, but further research is needed
to disentangle the contribution of each stage. The response to conspecific females was much less affected by the treatments
in relation to first arm choice and times in olfactometer arms, suggesting a pheromone-mediated behaviour, even though a prompter
and more intense wing fanning courtship behaviour was registered in the ND/NE males compared to males from the AD/NE treatment.
These results show that sexual behaviours are less affected by early experiences than behaviours related with finding a HPC
for foraging or oviposition. Taken together, our results demonstrate for first time that larval and eclosion experiences affect
in a differential way the early responses of the adult towards environment-derived cues and mate related cues. 相似文献
290.
Ernesto Salzano Francesco Cammarota Almerinda Di Benedetto Valeria Di Sarli 《Journal of Loss Prevention in the Process Industries》2012,25(3):443-447
The effects of enriching natural gas with hydrogen on local flame extinction, combustion instabilities and power output have been widely studied for both stationary and mobile systems. On the contrary, the issues of explosion safety for hydrogen–methane mixtures are still under investigation.In this work, experimental tests were performed in a 5 L closed cylindrical vessel for explosions of hydrogen–methane mixtures in stoichiometric air. Different compositions of hydrogen–methane were tested (from pure methane to pure hydrogen) at varying initial pressures (1, 3 and 6 bar).Results have allowed the quantification of the combined effects of both mixture composition (i.e., hydrogen content in the fuel) and initial pressure on maximum pressure, maximum rate of pressure rise and burning velocity. The measured burning velocities were also correlated by means of a Le Chatelier’s Rule-like formula. Good predictions have been obtained (at any initial pressure), except for mixtures with hydrogen molar content in the fuel higher than 50%. 相似文献