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21.
Long-term monitoring data show that hard coral cover on the Great Barrier Reef (GBR) has reduced by >70 % over the past century. Although authorities and many marine scientists were in denial for many years, it is now widely accepted that this reduction is largely attributable to the chronic state of eutrophication that exists throughout most of the GBR. Some reefs in the far northern GBR where the annual mean chlorophyll a (Chl a) is in the lower range of the proposed Eutrophication Threshold Concentration for Chl a (~0.2–0.3 mg m−3) show little or no evidence of degradation over the past century. However, the available evidence suggests that coral diseases and the crown-of-thorns starfish will proliferate in such waters and hence the mandated eutrophication Trigger values for Chl a (~0.4–0.45 mg m−3) will need to be decreased to ~0.2 mg m−3 for sustaining coral reef communities. 相似文献
22.
The relationships between age (range: 3 to 14 yr), mandibular bone fluoride level (marker of accumulated internal dose, range: 597 to 4680 mg F- kg-1> dry wt) and intensity of dental fluorosis (reflecting fluoride exposure during enamel formation) were studied in a sample of 53 fluorosed red deer from a fluoride-polluted area in the Czech-German border region (Ore mountains and their southern foreland). Assessment of the severity of dental fluorosis was performed for the 3 permanent premolars and 3 molars of one hemimandible per animal by using an ordinal measurement scale. For statistical analysis, the maximum tooth score of fluorosis (MTS) and the dental lesion index of fluorosis (DLI, sum of the six tooth scores per individual) were used. In the sample, both MTS (rs = 0.850) and DLI (rs = 0.813) were highly significantly (p <0.00001) correlated with bone fluoride content. A weaker correlation existed between age and bone fluoride content (rs = 0.322, p <0.05). The results demonstrate that in case of regional, long-term fluoride pollution, dental fluorosis (measured as MTS or DLI) can be used as a sensitive biomarker of fluoride exposure in deer and thus as an indicator of the level of environmental contamination by fluorides. In many countries, skulls and mandibles of wild deer are regularly and continuously collected by hunters. Assessment of the prevalence and severity of dental fluorosis in this material offers the opportunity for an efficient large-scale biomonitoring of environmental pollution by fluorides at very low cost. 相似文献
23.
In situ trampling occurred under experimental conditions to quantify the differences in the responses to anthropogenic trampling
in four dominant species of Hawaiian corals, Porites compressa, Porites lobata, Montipora capitata, and Pocillopora meandrina. Trampling was simulated daily for a period of nine days at which time further breakage was minimal. Forty treatment colonies
produced 559 fragments. Trampling was followed by an 11-month recovery period.
Coral colony and fragment mortality was low. All four species were highly tolerant of inflicted damage, suggesting that some
species of corals can withstand limited pulse events that allow time for recovery.
Growth rates following trampling were significantly lower in the treatment groups for three of the four species. This study
demonstrated that very few trampling events can produce significant changes in growth even after a long recovery period.
Survivorship of fragments is clearly size- and species-dependent in M. capitata and P. compressa. Smaller fragments (<5 cm) had higher mortality than larger fragments (>5 cm). High breakage rates for M. capitata and P. compressa are consistent with the nearshore, low-energy regions they inhabit—the same environment frequented by skin divers and waders.
Mechanical tests were conducted to determine tensile and compressive strengths. Pocillopora meandrina exhibited the strongest skeletal strength, followed in decreasing order by Porites lobata, Porites compressa, and Montipora capitata. The skeletal strength obtained from the experiments correlate with the wave energy present in the environments in the regions
they inhabit, suggesting that structural strength of corals is an adaptive response to hydraulic stress. 相似文献
24.
为了探讨硒弹对山羊工业氟中毒的预防效果,把160只6—10月龄的本地山羊,分成一个对照组和三个补硒组,在氟重污染牧场上放牧18个月.同时,对一些血清酶及免疫功能进行了测定.补硒组与对照组相比,GSH-px及T-淋巴细胞转化率升高,而NAP.ALP、骨源性ALP、GOT降低.最后讨论了硒预防山羊氟中毒的机理及硒弹的应用前景. 相似文献
25.
26.
A health risk assessment for fluoride in Central Europe 总被引:4,自引:0,他引:4
Fordyce FM Vrana K Zhovinsky E Povoroznuk V Toth G Hope BC Iljinsky U Baker J 《Environmental geochemistry and health》2007,29(2):83-102
Like many elements, fluorine (which generally occurs in nature as fluoride) is beneficial to human health in trace amounts,
but can be toxic in excess. The links between low intakes of fluoride and dental protection are well known; however, fluoride
is a powerful calcium-seeking element and can interfere with the calcified structure of bones and teeth in the human body
at higher concentrations causing dental or skeletal fluorosis. One of the main exposure routes is via drinking water and the
World Health Organisation currently sets water quality guidelines for the element. In Central Europe, groundwater resources
that exceed the guideline value of 1.5 mg l−1 are widespread and effects on health of high fluoride in water have been reported. The aim of the current project was to
develop a geographic information system (GIS) to aid the identification of areas where high-fluoride waters and fluorosis
may be a problem; hence, where water treatment technologies should be targeted. The development of the GIS was based upon
the collation and digitisation of existing information relevant to fluoride risk in Ukraine, Moldova, Hungary and Slovakia
assembled for the first time in a readily accessible form. In addition, geochemistry and health studies to examine in more
detail the relationships between high-fluoride drinking waters and health effects in the population were carried out in Moldova
and Ukraine demonstrating dental fluorosis prevalence rates of 60–90% in adolescents consuming water containing 2–7 mg l−1 fluoride. 相似文献
27.
Dental fluorosis associated with drinking water from hot springs in Choma district in southern province,Zambia 总被引:2,自引:0,他引:2
Shitumbanuma V Tembo F Tembo JM Chilala S Van Ranst E 《Environmental geochemistry and health》2007,29(1):51-58
This study was conducted to investigate the high incidence of mottled teeth among residents of an area with hot springs in
the Choma District of the Southern Province of Zambia. A survey involving 128 pupils was conducted at a Basic School to collect
data on pupil’s backgrounds and their main sources of drinking water between birth and age 7. A dental specialist examined
the pupils’ teeth and samples of drinking water were collected from locations where the majority of the pupils lived. It was
analysed for fluorides and other drinking water quality parameters. Results of the survey showed a highly significant (P < 0.001) association between pupils’ main sources of drinking water between birth and age 7 and the incidence of discoloured
teeth. All (100%) pupils who drank water from hot springs before age 7 had moderate to severe fluorosis, while the majority
(96.7%) of the pupils who drank water from other sources had no dental fluorosis. Fluoride concentrations ranged from 5.95
to 10.09 mg/l in water from hot springs, and from 0.03 to 0.6 mg/l in water from other sources. Fluoride levels in water from
hot spring water samples exceeded the 1.5 mg/l WHO guideline value for drinking water, while those in water from other sources
were significantly (P < 0.05) lower than this. We conclude that the high prevalence of mottled teeth among residents of the study area is a case
of endemic dental fluorosis associated with drinking water from hot springs containing high concentrations of fluoride. 相似文献
28.
Chandrajith R Abeypala U Dissanayake CB Tobschall HJ 《Environmental geochemistry and health》2007,29(5):429-434
The purpose of this study was to assess the fluoride content of Ceylon Tea, which is a popular beverage throughout the world.
The fluoride content of tea infusions prepared from different grades of tea leaves collected from different parts of the tea-growing
regions (25 samples) of Sri Lanka was measured using a fluoride-selective electrode. Fluoride leaching was found to vary from
0.32 to 1.69 mg F/l, but there were no significant differences in terms of fluoride leaching between tea from different tea-growing
regions or between tea of different grades. Dental fluorosis is widespread throughout the dry zone of Sri Lanka, and drinking
water has traditionally been considered to be the main contributory factor to the development of fluorosis. However, diet,
the consumption of tea in particular, may also contribute to the manifestation of dental diseases. 相似文献
29.
Soromon Kataoka Hideaki Sawai Hideto Yamada Nozomi Kanazawa Koji Koyama Gen Nishimura Mamoru Morikawa Noriaki Sakuragi Hisanori Minakami 《黑龙江环境通报》2004,24(1):45-49
Hypochondroplasia is an autosomal dominant skeletal dysplasia expressing postnatal onset of short stature with mild rhizomelic shortening of the limbs. This manifestation leads to restricted prenatal diagnosis of the disorder. We report here on a sporadic case of a hypochondroplastic baby, whose prenatal sonographic measurements were serially recorded from 19 weeks of gestation. Mild shortening of the limbs became manifest after 26 weeks of gestation. Biparietal diameter was within the normal range throughout gestation. Both parents were of average stature. A tentative diagnosis of a nonlethal short-limb skeletal dysplasia was made. At birth, the clinical manifestations of the neonate were not characteristic, but the radiographic features raised the possibility of hypochondroplasia. Molecular analyses revealed a C to G mutation at nucleotide 1659 of the fibroblast growth factor receptor 3 (FGFR3) gene, a common mutation in hypochondroplasia. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
30.
Albert C. F. Lam Daniel H. C. Chan Tony M. F. Tong Mary H. Y. Tang Steven Y. F. Lo Ivan F. M. Lo Stephen T. S. Lam 《黑龙江环境通报》2006,26(11):1018-1020
We present the first confirmed case by molecular analysis of a metaphyseal chondrodysplasia, McKusick type, in a 22-week fetus. Two novel compound heterozygous mutations, 64T> A and 79G > T, were found in the highly conserved regions of the RMRP gene. Twenty-two heterozygous g.1018 T> C mutations, two homozygous g.1018 T> C mutations, two heterozygous insertion mutations g.799_g.800insC and one heterozygous insertion mutation g.849_g.850insT were found among 100 normal controls. Careful radiological examination of the fetus for skeletal dysplasia allowed definitive diagnosis, proper genetic counselling and future prenatal diagnosis. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献