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The uptake and metabolism of 14C-L-leucine by Cystoclonium purpureum (Huds) Batt. (Rhodophyllidaceae) at concentrations of 0.5–50 μM were studied. Leucine was taken up from seawater at rates of 10–160 nmol·g-1 fresh weight·h-1. At low leucine levels ( 5 μM) the amino acid was preferably incorporated into cellular protein; amine formation was less than 5%. However at leucine concentrations of 50 μM, more than 30% of the total leucine taken up was decarboxylated to 3-methylbutylamine. This effect is expressed even more in Dumontia increassata (O. F. Müll) Lamour. (Dumontiaceae). In both species some of the amine occurred as a non-volatile derivative (bound amine) from which free amine could quantitatively be released by acid hydrolysis. Leucine and amine uptake were inhibited by CCCP. However, from cells preloaded with both leucine and amine, only free amine is released in the presence of CCCP. The results indicate that decarboxylase activity will be switched on at increased levels of amino acids in seawater which may be expected frequently in habitats of littoral algae (tidal zone). A possible function of amine formation and release within the scope of chemical defence of benthic algae is discussed. 相似文献
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The Science of Nature - 相似文献
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Martine Rowell-Rahier Ludger Witte Adelheid Ehmke Thomas Hartmann Jacques M. Pasteels 《Chemoecology》1991,2(1):41-48
Summary
Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima. 相似文献
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Laturnus F Fahimi I Gryndler M Hartmann A Heal MR Matucha M Schöler HF Schroll R Svensson T 《Environmental science and pollution research international》2005,12(4):233-244
- DOI: http:/dx.doi.org/10.1065/espr2005.06.262
Goal, Scope and Background The anthropogenic environmental emissions of chloroacetic acids and volatile organochlorines have been under scrutiny in
recent years because the two compound groups are suspected to contribute to forest dieback and stratospheric ozone destruction,
respectively. The two organochlorine groups are linked because the atmospheric photochemical oxidation of some volatile organochlorine
compounds is one source of phytotoxic chloroacetic acids in the environment. Moreover, both groups are produced in higher
amounts by natural chlorination of organic matter, e.g. by soil microorganisms, marine macroalgae and salt lake bacteria,
and show similar metabolism pathways. Elucidating the origin and fate of these organohalogens is necessary to implement actions
to counteract environmental problems caused by these compounds.
Main Features While the anthropogenic sources of chloroacetic acids and volatile organochlorines are relatively well-known and within human
control, knowledge of relevant natural processes is scarce and fragmented. This article reviews current knowledge on natural
formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soils, with particular emphasis
on processes in the rhizosphere, and discusses future studies necessary to understand the role of forest soils in the formation
and degradation of these compounds.
Results and Discussion Reviewing the present knowledge of the natural formation and degradation processes of chloroacetic acids and volatile organochlorines
in forest soil has revealed gaps in knowledge regarding the actual mechanisms behind these processes. In particular, there
remains insufficient quantification of reliable budgets and rates of formation and degradation of chloroacetic acids and volatile
organochlorines in forest soil (both biotic and abiotic processes) to evaluate the strength of forest ecosystems regarding
the emission and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale.
Conclusion It is concluded that the overall role of forest soil as a source and/or sink for chloroacetic acids and volatile organochlorines
is still unclear; the available laboratory and field data reveal only bits of the puzzle. Detailed knowledge of the natural
degradation and formation processes in forest soil is important to evaluate the strength of forest ecosystems for the emission
and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale.
Recommendation and Perspective As the natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soil can
be influenced by human activities, evaluation of the extent of this influence will help to identify what future actions are
needed to reduce human influences and thus prevent further damage to the environment and to human health caused by these compounds. 相似文献