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731.
Parasite faunas,testosterone and secondary sexual traits in male red-winged blackbirds 总被引:3,自引:0,他引:3
Patrick J. Weatherhead Karen J. Metz Gordon F. Bennett Rebecca E. Irwin 《Behavioral ecology and sociobiology》1993,33(1):13-23
Summary We examined associations among parasite infections, secondary sexual traits and testosterone in male red-winged blackbirds sampled at the start of the breeding season. Parasites quantified included ectoparasitic lice and mites and endoparasitic blood protozoans, nematodes, trematodes and cestodes. Secondary sexual traits that we quantified included body size, epaulet size and color, song repertoire size and song switching rate, and behavioral responses to male and female models. Overall we found few significant associations between parasites and secondary sexual traits, between secondary sexual traits and testosterone, or between parasites and testosterone. In addition, most parasite taxa appeared to infect birds independently, although the low prevalence (<50%) of many of the parasites meant that our sample sizes were too small to detect weak associations. Our most promising results were obtained for ectoparasitic mites, which tended to occur on birds uninfected with other parasites, on birds with longer epaulets, and on birds with higher levels of testosterone. Epaulet length and testosterone are both probable correlates of dominance in this species. Further research will be required to determine whether there is a causal link between the immunosuppressive effects of testosterone and the mite infections, and between testosterone, epaulet length and male mating success.
Correspondence to: P. Weatherhead 相似文献
732.
Northern shrimp Pandalus borealis (Krøyer) larvae hatch in the northern Gulf of St. Lawrence from early May to the end of June, and larval development occurs over a range of relatively cold water temperatures. Because of the long duration of the pelagic phase and the difficulty of sampling all successive larval stages at sea, we used laboratory experiments to assess the effects of water temperature on larval development and growth. In spring 2000, P. borealis larvae were reared from hatching to the first juvenile stages (i.e., stage VI and VII) at three temperatures (3, 5, and 8°C) representing conditions similar to those in spring in the northern Gulf of St. Lawrence. Larval development and growth were dependent on temperature, with longer duration and smaller size (cephalothorax length, CL, and dry mass, DM) at 3°C relative to the 5 and 8°C treatments. There were no significant differences in the morphological characters of the different stages among treatments, indicating that regular moults occurred at each temperature. The results suggest a negative impact of cold temperatures (lower intra-moult growth rates and smaller size) and, possibly, higher cumulative mortality due to longer development time that could affect the success of cohorts at sea. However, CL and DM for stage III and later larvae were smaller than those of larvae identified at the same developmental stage in field locations. It is possible that the diet offered to larvae in this experiment (Artemia nauplii, either newly hatched nauplii or live adults, depending on the developmental stage) was not optimal for growth, even though it is known to support successful P. borealis larval development. In the field, there is the possibility that phytoplankton contributes to the larval diet during the first stages and stimulates development of the digestive glands. Furthermore, the nutritional quality of the natural plankton diet (e.g., high protein content, fatty acid composition) might be superior and favourable to higher growth rates even at lower temperatures.Communicated by R.J. Thompson, St. Johns 相似文献
733.
Hélène Hégaret Gary H. Wikfors Philippe Soudant Christophe Lambert Sandra E. Shumway Jean Baptiste Bérard Patrick Lassus 《Marine Biology》2007,152(2):441-447
The possible effect of Alexandrium spp. containing paralytic shellfish poisoning (PSP) toxins on the hemocytes of oysters was tested experimentally. In one
trial, eastern oysters, Crassostrea virginica Gmelin, were exposed to bloom concentrations of the sympatric dinoflagellate, Alexandrium
fundyense Balech, alone and in a mixture with a non-toxic diatom, Thalassiosira weissflogii (Grun) Fryxell et Hasle. Subsequently, another experiment exposed Pacific oysters, Crassostrea gigas Thunberg, to a mixed suspension of the sympatric, toxic species Alexandrium catenella (Whedon et Kofoid) Balech, with T. weissflogii. Measurements of numbers of oyster hemocytes, percentages of different cell types, and functions (phagocytosis, reactive
oxygen species (ROS) production, and mortality) were made using flow-cytometry. During and after exposure, almost no significant
effects of Alexandrium spp. upon hemocyte numbers, morphology, or functions were detected, despite observations of adductor-muscle paralysis in
C. virginica and measured toxin accumulation in C. gigas. The only significant correlation found was between toxin accumulation at one temperature and higher numbers of circulating
live and dead hemocytes in C. gigas. The PSP toxins are known to interfere specifically with sodium-channel function; therefore, the finding that the toxins
had no effect on measured hemocyte functions suggests that sodium-channel physiology is not important in these hemocyte functions.
Finally, because oysters were exposed to the living algae, not purified toxins, there was no evidence of bioactive compounds
other than PSP toxins affecting hemocytes in the two species of Alexandrium studied. 相似文献
734.
Post-socialist forest disturbance in the Carpathian border region of Poland, Slovakia, and Ukraine. 总被引:3,自引:0,他引:3
Tobias Kuemmerle Patrick Hostert Volker C Radeloff Kajetan Perzanowski Ivan Kruhlov 《Ecological applications》2007,17(5):1279-1295
Forests provide important ecosystem services, and protected areas around the world are intended to reduce human disturbance on forests. The question is how forest cover is changing in different parts of the world, why some areas are more frequently disturbed, and if protected areas are effective in limiting anthropogenic forest disturbance. The Carpathians are Eastern Europe's largest contiguous forest ecosystem and are a hotspot of biodiversity. Eastern Europe has undergone dramatic changes in political and socioeconomic structures since 1990, when socialistic state economies transitioned toward market economies. However, the effects of the political and economic transition on Carpathian forests remain largely unknown. Our goals were to compare post-socialist forest disturbance and to assess the effectiveness of protected areas in the border triangle of Poland, Slovakia, and Ukraine, to better understand the role of broadscale political and socioeconomic factors. Forest disturbances were assessed using the forest disturbance index derived from Landsat MSS/TM/ETM+ images from 1978 to 2000. Our results showed increased harvesting in all three countries (up to 1.8 times) in 1988-1994, right after the system change. Forest disturbance rates differed markedly among countries (disturbance rates in Ukraine were 4.5 times higher than in Poland, and those in Slovakia were 4.3 times higher than in Poland), and in Ukraine, harvests tended to occur at higher elevations. Forest fragmentation increased in all three countries but experienced a stronger increase in Slovakia and Ukraine (approximately 5% decrease in core forest) than in Poland. Protected areas were most effective in Poland and in Slovakia, where harvesting rates dropped markedly (by nearly an order of magnitude in Slovakia) after protected areas were designated. In Ukraine, harvesting rates inside and outside protected areas did not differ appreciably, and harvests were widespread immediately before the designation of protected areas. In summary, the socioeconomic changes in Eastern Europe that occurred since 1990 had strong effects on forest disturbance. Differences in disturbance rates among countries appear to be most closely related to broadscale socioeconomic conditions, forest management practices, forest policies, and the strength of institutions. We suggest that such factors may be equally important in other regions of the world. 相似文献
735.
The diet of white-chinned petrels Procellaria aequinoctialis breeding at the Crozet Archipelago (southern Indian Ocean) was studied using two complementary methods: lipid analysis of
stomach oils as trophic markers together with the conventional dietary approach (i.e., stomach content analysis). Objectives
were (1) to investigate the adult diet when they feed for themselves by analyzing stomach oil lipids, and (2) to compare the
lipid signature of chick and adult oils. Stomach oils mainly consisted of triacylglycerols (TAG), diacylglycerol-ethers (DAGE)
and wax esters (WE) (66, 14 and 11%, respectively). The dietary origin of TAG and WE was evaluated by linear discriminant
analyses with fatty acid and fatty alcohol fractions. Analyses evidenced that stomach oils did not originate from Antarctic
krill, but instead from myctophid fish, thus demonstrating the importance of mesopelagic fish in the nutrition of adult petrels.
This result was consistent with the identification of digested remains of myctophids recovered from adult stomach contents
after long foraging trips. Large amounts of a rare lipid class, DAGE (up to 76% of total lipids), were identified in two stomach
oils, together with fresh remains of the squid Gonatus antarcticus (99% by mass), suggesting that DAGE could have the potential to be trophic markers of cephalopods. Moreover, six oils probably
originated from Patagonian toothfish, thus confirming strong interactions between white-chinned petrels and fisheries. Comparison
between chick and adult stomach oils indicated no major differences in their biochemical composition suggesting an identical
dietary origin of oils, mainly myctophids. Both adult and chick oils can therefore be used to determine the feeding ecology
of adult birds when they feed far away from their breeding grounds. Finally, food analysis of chick samples and adult samples
collected after short and long trips indicated different foraging grounds during the two kinds of trips, and also between
long trips performed in subtropical and Antarctic waters. 相似文献
736.
南非政府最近贯彻了一项免费向消费者,特别是贫困人口,供应基本用水的政策.通过被称之为"链式输送"的创新公私合作计划,一直在为农村提供用水基础设施.在重视合理使用政府开支、维护可持续性以及实现社会目标的同时,"链式输送"在确保提供用水和卫生设备工作快速进行中发挥了积极作用. 相似文献
737.
Summary We present the first experiment to assess band color effects in a natural bird population. 38 territorial male red-winged blackbirds (Agelaius phoeniceus) were randomly assigned to 1 of 2 banding treatments. They received either all red bands (to match their epaulets) or all black bands (controls). Over half the red-banded males lost their territories while all black-banded males retained their territories. Red and black-banded males did not differ morphologically. However, among red-banded males, those that lost their territories had larger epaulets and were in poorer condition than those retaining their territories. Red-banded males suffered much higher intrusion rates, particularly by neighbors, than black-banded males. We propose that red color bands exaggerated the males' natural aggressive signal beyond the point where the signal was reliable. Our results suggest that signal reliability is maintained by regular testing, particularly of those males most likely to be signalling dishonestly.
Offprint requests to: K.J. Metz 相似文献
738.
Mei Wang John Mata Christopher E. Price Patrick L. Iversen Maurice Godfrey 《黑龙江环境通报》1995,15(6):499-507
The Marfan syndrome (MFS) is a heritable connective tissue disorder characterized by skeletal, ocular, and cardiovascular abnormalities. Defects in fibrillin, an elastin-associated microfibrillar protein, are now known to cause MFS. Since the discovery of fibrillin as the gene responsible for MFS, requests for prenatal and presymptomatic diagnosis have become common-place. Here we report the use of the polymerase chain reaction (PCR), using fluorescence labelled primers and an automated sequencer, to establish linkage data for “molecular diagnosis”. The mistaken clinical diagnosis of MFS based on the appearance of a common cardiovascular manifestation, mitral valve prolapse, and a positive family history is also discussed. 相似文献
739.
The effect of chloroquine, quinacrine, and metronidazole on both soybean plants and soil microbiota 总被引:7,自引:0,他引:7
Jjemba PK 《Chemosphere》2002,46(7):1019-1025
Chloroquine, quinacrine, and metronidazole are used extensively for therapeutic purposes. Substantial quantities of these compounds end up in the environment. The potential effect of these compounds on soybean and on the protozoa in soil was assessed. The growth of soybean plants was affected by increasing concentrations of the chloroquine, metronidazole, and quinacrine dihydrochloride. The plants were particularly sensitive to low concentrations of metronidazole. The number of bacteria and protozoa in soil was either unchanged or increased in the presence of chloroquine and quinacrine. However, in the presence of only 0.5 mg metronidazole g(-1) soil, the density of protozoa in the rhizosphere was reduced by a 10-fold. 相似文献
740.
Goemans M Clarysse P Joannès J De Clercq P Lenaerts S Matthys K Boels K 《Chemosphere》2004,54(9):1357-1365
The engineering, construction, performance and running costs of a catalytic flue gas cleaning component in the low dust area of a municipal waste incinerator is discussed. For this purpose, the case study of a Flemish incineration plant is presented, covering the history, the design procedure of the catalyst, relevant process data and the financial aspects. A reliable PCDD/F-destruction by means of oxidation by the catalyst to typical values of 0.001 ng TEQ/Nm3 has been demonstrated. At the same time, NOx- and CO-emissions are reduced by 90% and 20% to about 50 mg/Nm3 and below 10 mg/Nm3, respectively. 相似文献