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排序方式: 共有262条查询结果,搜索用时 125 毫秒
241.
Françoise Muller Marc Dommergues Yves Ville Fanny Lewin Nicole Delvalez-Morichon Claire Nihoul-Fekete Fréderic Bargy Yves Dumez André Boue 《黑龙江环境通报》1994,14(10):973-979
The diagnostic value of amniotic fluid gamma-glutamyl-transpeptidase (GGTP) and intestinal alkaline phos-phatase (iALP) was evaluated in 55 patients who underwent amniocentesis for karyotyping because fetal gastric or small bowel dilatation had been detected by ultrasound. Gastrointestinal malformation was confirmed in 46 cases and there was no gastrointestinal anomaly in nine cases. Prenatal ultrasound was suggestive of gastroduodenal dilatation in 34 cases (group I) and small bowel dilatation in 21 cases (group II). In group I, amniotic fluid GGTP above the 99th percentile was 71 per cent sensitive and 100 per cent specific for a true anatomical defect of the digestive tract (mainly duodenal atresia). In group II, high levels of GGTP and/or iALP were 69 per cent sensitive and 83 per cent specific for a fetal digestive tract anomaly. In other words, when digestive tract dilatations were diagnosed by prenatal sonography, abnormal amniotic fluid enzyme activities were strongly suggestive of such an anomaly, the possibility of which was not precluded by normal amniotic fluid iALP and GGTP activities. But amniotic fluid digestive enzyme activities do not help in defining the prognosis. 相似文献
242.
The zoeal larvae of brachyuran crabs must feed soon after hatching on a diet that includes large micro- and mesozooplankton
in order to satisfy nutritional requirements. However, newly hatched larvae have been shown to ingest a variety of dinoflagellates,
perhaps using microbial carbon sources to sustain them until they encounter more favored prey. Ingestion of dinoflagellates
by larval crabs has been documented previously under conditions in which the larvae were exposed to algae provided in monoculture
or in defined mixtures of cells. We report here on experiments conducted on the hatching stage of five crab species to determine
if ingestion of dinoflagellates occurred when they were provided in combination with Artemia sp. nauplii or after a period of feeding on mesozooplankton. Quantitative measurements of chl a in the larval guts provided evidence of ingestion of algal cells. Active ingestion of the dinoflagellate Prorocentrum micans at specified intervals during an extended feeding period was determined on larvae of two crab species using fluorescently
labeled cells provided for brief periods at prescribed time intervals. Stage 1 larvae of four of the five crab species ingested
dinoflagellates when they were provided in combination with nauplii and larvae of all five species ingested cells after feeding
solely on nauplii for 24 h. Ingestion of algal cells was first evident in the larval guts after 6 h of feeding at both low
(200 cell ml−1) and high (1,000 cells ml−1) prey densities. Higher prey densities resulted in higher gut chl a. Larvae continuously exposed to dinoflagellates actively ingested cells at every 3 h interval tested over a 36 h period.
Results confirm previous studies that larvae will ingest dinoflagellates even when they are encountered in a mixed prey field
or when having previously fed. Ingestion of cells may occur on a continual basis over time. 相似文献
243.
Robert J. Paxton Nicole Weißschuh Wolf Engels Klaus Hartfelder J. Javier G. Quezada-Euan 《Die Naturwissenschaften》1999,86(3):143-146
Queens of the large, pantropical and fully eusocial taxon Meliponinae (stingless bees) are generally considered to be singly
mated. We indirectly estimated queen mating frequency in two meliponids, Melipona beecheii and Scaptotrigona postica, by examining genotypes of workers at microsatellite DNA loci. Microsatellites were highly variable, providing suitable markers
with which to assign patrilinial origin of workers within colonies headed by single queens. Queen mating frequency varied
between 1 and 3 (M. beecheii) and 1 and 6 (S. postica), representing the first clear documentation of polyandry in the Meliponinae. Effective paternity frequency, m
e
, was lower, although above 2 for S. postica. Stingless bees may provide suitable subjects for the testing of recent inclusive fitness arguments describing intracolony
kin conflict in social Hymenoptera.
Received: 26 August 1998 / Accepted in revised form: 18 November 1998 相似文献
244.
Urs Baumann Caroline Brunner Ernst Pletscher Nicole Tobler 《Environmental Sciences Europe》2003,15(3):163-167
The goal of this work is to make ecotoxicologically-relevant substance bands visible on thin-layer chromatographic plates. Bacteria (Bacillus subtilis, Vibrio fischeri, Salmonella typhimurium), fungi (Aspergillus niger), algi (Pseudokirchneriella subcapitata) and pollen (Impatiens walleriana) were used as test organisms. With the aid of these organisms, it has been possible to identify bactericide, fungicide, algicide, phytotoxic and genotoxic bands. 相似文献
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249.
Borth Priscila Liane Biesdorf Perin Jessica Klarosk Helenas Torrecilhas Arthur Ribeiro Pan Nicole Caldas Kuroda Emília Kiyomi Fernandes Fernando 《Journal of Material Cycles and Waste Management》2021,23(5):1974-1983
Journal of Material Cycles and Waste Management - The objective of this study is to evaluate the influence of the addition of garden waste (GW) on the performance of food waste (FW) anaerobic... 相似文献
250.
Julie K. Desjardins Kelly A. Stiver John L. Fitzpatrick Nicole Milligan Glen J. Van Der Kraak Sigal Balshine 《Behavioral ecology and sociobiology》2008,62(5):785-794
Among taxonomically widespread cooperatively breeding vertebrates, those with non-breeding helpers-at-the-nest provide an
excellent opportunity to understand the proximate mechanisms underlying care and allocare. In this study, we examined androgen
levels in relation to care behavior in a cooperatively breeding cichlid fish, Neolamprologus pulcher, from Lake Tanganyika. We concentrated on androgens, as these hormones have been linked to the defense behavior, and the
defense of young is a common form of parental care in fishes. N. pulcher dominant female breeders performed the most care and also displayed the highest levels of plasma testosterone (T) compared
with other individuals within the social group. We also found that dominant male breeders provided a similar amount of care
as did the subordinate helpers, but breeding males had the highest levels of 11-ketotestosterone (11KT), an important androgen
in fish. Breeders had higher levels of both androgens (T and 11KT) compared to helpers. There was a weak but significant positive correlation between T levels and the frequency of
care regardless of sex and status. Our results suggest that androgens may promote defense of young and are in contrast to
the commonly reported trade-off between androgen and parental care. 相似文献