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31.
To determine whether the appearance of a reproductively parasitic tactic varies, and how this variation affects territorial
males of the Lake Tanganyika cichlid fish Telmatochromis vittatus, we examined the reproductive ecology of territorial males in Mtondwe and compared it with that of a neighboring Wonzye population,
where nest density differs from that at Mtondwe. In Wonzye, with high nest density, male tactics change with their body size
from a territorial to a non-territorial parasitic tactic called piracy in which they conquer several nests defended by territorial
males and take over the nests while females are spawning. These “pirate” males could decrease the costs incurred by travelling
among nests by exclusively targeting aggregations of nests in close proximity while avoiding separate nests. Territorial males
in Wonzye sacrifice the potential higher attractiveness offered by large nests and instead compete for nests farther from
neighbors on which pirates less frequently intrude. In contrast, the Mtondwe population had lower nest density and piracy
was absent. Given that the success of piracy depends on the close proximity of nests, nest density is likely responsible for
the observed variation in the occurrence of piracy between the two populations. Furthermore, in Mtondwe, territorial males
competed for larger nests and were smaller than the territorial males in Wonzye. Thus, this lower nest density may free territorial
males from the selection pressures for increased size caused by both defense against nest piracy and the need to develop into
pirates as they grow. 相似文献
32.
33.
Mamoru Nishioka Nakamichi Yamasaki Hiroshi Amano Masanori Higuchi 《Waste management (New York, N.Y.)》1992,12(4)
Tritium is generally disposed of as an oxide form, and immobilization of tritium oxide with Portland cement is the most popular disposal method. However, the cement solidified body is rather leachable for tritium and is poor in some physical properties. A silicate powder, such as borosilicate glass powder, forms a synthetic rock by the hydrothermal hot-pressing (HHP) technique, making it a technique for immobilization of tritium oxide. Tritium oxide with borosilicate glass powder was solidified by the HHP technique. Leachability of tritium from the produced solidified bodies and the behavior of fixed tritium oxide during the heating were studied and discussed. The amount of tritium oxide fixed by the present procedure was almost the same as that fixed by the ordinary cement solidifying procedure. The diffusivity of tritium from the body by this procedure was much lower than that from the cement body and the compressive strength of the body was higher than that of the cement body. 相似文献
34.
A sample of commercial BADGE was fractioned by HPLC and eight impurities including novel propyl derivatives (2), (5) and (6) were identified by NMR spectrometry, FAB-MS and GC-MS. The estrogenicity, both agonist and antagonist, of fractions containing these impurities was measured with a yeast two-hybrid assay incorporating the human (hER alpha) and a competitive binding assay for hER alpha (ELISA). In the yeast two-hybrid assay, estrogenic antagonist activity was found in two fractions, while estrogenic agonist activity was not found in any. In the ELISA method, the binding affinity to hER alpha was found in three fractions. It is probable that a comprehensive assessment of the estrogenic properties of commercial BADGE, and their implications for human health, will require examination of all its components as described here. 相似文献
35.
Inoue M Tanaka K Watanabe S Kofuji H Yamamoto M Komura K 《Journal of environmental radioactivity》2006,89(2):138-149
In this study, low-background gamma-spectrometry was used to determine the (228)Ra/(226)Ra ratio of 131 coastal water samples from various environments around Honshu Island, Japan (mainly around Noto Peninsula) at 1-3 month intervals from April 2003 until September 2005. Spatial variation in (228)Ra/(226)Ra ratios was also assessed by analyzing 34 coastal water samples from five areas within the Sea of Japan during May and June 2004. The (228)Ra/(226)Ra ratio of coastal water from all sites around Noto Peninsula shows seasonal variation, with minimum values during summer ((228)Ra/(226)Ra=0.7) and maximum values during autumn-winter ((228)Ra/(226)Ra=1.7-2). This seasonal variation is similar to that recorded for coastal water between Tsushima Strait and Noto Peninsula. The measured lateral variation in (228)Ra/(226)Ra ratios within coastal water between Tsushima Strait and Noto Peninsula is only minor (0.5-0.7; May-June 2004). Coastal waters from two other sites (Pacific shore and Tsugaru Strait, north Honshu) show no clear seasonal variation in (228)Ra/(226)Ra ratio. These measured variations in (228)Ra/(226)Ra ratio, especially the temporal variations, have important implications for seasonal changes in patterns of coastal water circulation within the Sea of Japan. 相似文献
36.
37.
Rosales-Hurtado Miyanou Duvauchelle Valentin Bénimélis David Ogawa-Okada Maya Yamamoto Naofumi Meffre Patrick Szurmant Hendrik Benfodda Zohra 《Environmental Chemistry Letters》2023,21(1):47-53
Environmental Chemistry Letters - The rise of bacterial resistance to common clinical antibiotics is calling for alternative techniques to synthesize antibacterial drugs with high biodegradability.... 相似文献
38.
39.
Early development was examined, under various salinities, for two sympatric nereidid polychaetes, Hediste japonica and H. diadroma, which participated in a simultaneous reproductive swarming in an estuary of the Omuta-gawa River in Ariake Sea, Japan. The
eggs of both species were isotonic to the medium of 27.5–30 psu salinity. The egg diameter in the isotonic salinity was 180–205 μm
in H. japonica, and 130–160 μm in H. diadroma. Successful development of most embryos was observed in a salinity range of 22.5–30 psu in both species, while successful
fertilization occurred in wider ranges of salinity, i.e., 10–34 psu in H. japonica and 10 to 30 psu in H. diadroma. In both species, free-swimming larval life started from the indistinct hatching of trochophores out of a jelly layer capsule.
The lecithotrophic development appeared to run to the 4-setiger nectochaetes in H. japonica, while to 3-setiger nectochaetes in H. diadroma, resulting in a shorter pelagic larval life in H. japonica. In a comparison of larval morphology among Hediste species, we found a definite negative correlation between the prostomium width, which represents the larval size and depends
on egg size, and relative length of chaetae to the prostomium width: the relative length of chaetae was the longest in H. diadroma (with the smallest egg size and long pelagic life), intermediate in H. japonica (intermediate egg size, short pelagic life), and the shortest in H. atoka (largest egg size, no true pelagic life). We also examined the possibility of hybridization between H. japonica and H. diadroma through cross-insemination experiments. The gametes of the two species were reciprocally compatible, and viable hybrid offspring
were produced by the laboratory crosses. The hybrid larvae expressed intermediate phenotypes, but with a greater maternal
influence in characteristics such as the relative length of chaetae and the lecithotrophic larval duration. 相似文献
40.
S. Kojima S. Ohta T. Yamamoto T. Yamaguchi T. Miura Y. Fujiwara K. Fujikura J. Hashimoto 《Marine Biology》2003,142(4):625-635
The phylogenetic status of Alaysia-like vestimentiferans, which were collected at eight sites in the western Pacific, was analyzed on the basis of the nucleotide sequence of part of a mitochondrial gene for cytochrome oxidase I. The 123 individuals analyzed were tentatively classified into four species, which inhabit, respectively, seep areas off the central part of the Japanese mainland, hydrothermal vent fields in the Mid-Okinawa Trough, hydrothermal vent fields in the southern Okinawa Trough, and both seep and vent sites in the Bismarck Sea. From six additional lamellibrachiid specimens from two sites in the Bismarck Sea, two new tentative species were recognized, namely, one from a seep area off Papua New Guinea and another from the hydrothermal vent field at the DESMOS site in the Manus Basin. Phylogenetic analysis using all available sequences of six vestimentiferan families and Alaysia-like vestimentiferans revealed that vestimentiferans could be divided into three groups, namely, lamellibrachiids, escarpiids, and others, even though the monophyly of the third group was supported by only low bootstrap probabilities. Within the first group, the earliest divergence of a tentative lamellibrachiid species from the DESMOS site was apparent. All Alaysia-like vestimentiferans formed a monophyletic group with Arcovestia ivanovi from the Manus Basin, and it is suggested that this group might be derived from vestimentiferans that are endemic to the hydrothermal sites in the Eastern Pacific Rise. 相似文献