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71.
M. Gomendio J. Cassinello P. Bateson M. W. Smith 《Behavioral ecology and sociobiology》1995,37(2):71-80
Two treatments of hooded rat (Rattus norvegicus) mothers after the birth of their pups affected the stage of development at which their pups started to take solid food and showed an increase in the expression of sucrase, an enzyme needed for digesting solid food. The pups of mothers that became pregnant in a post-partum oestrus showed the changes significantly earlier than those in the control group (Fig. 1A, B). The pups of mothers that had been mildly food-restricted after birth showed the changes significantly later than those in the control group. In brief, the pups of the pregnant mothers weaned first, the control pups next and those of food-restricted mothers weaned last. Differences in the timing of weaning between the three groups occurred in the absence of differences in pup body weight at the time of weaning. Within each experimental group, on the day in which sucrase expression showed the first detectable increase, sucrase activity was strongly predicted by the weight of the pups shortly after birth (Fig. 3). Pregnant mothers put on weight rapidly before implantation and their pups prepared for early weaning even though they did not differ in body weight from control pups (Fig. 4A, B). Food-restricted mothers were significantly lighter than control mothers and, with lighter pups before weaning started, settled for a longer period of suckling. 相似文献
72.
The pollution is increasing in the environment by different kinds of human activities, which results in the accumulation of heavy metals including cadmium in the soil and water and it causes different types of problems to living beings. As the plants are utilized by human being as food and medicine, therefore, it is mandatory to see the effect of metals on plants. In this context, efforts have been made to observe the effect of different concentration of Cadmium (Cd) on Phyllanthus amarus Schum. and Thonn., because Cd is the widespread metal and the plants response to low and high level of exposure is a complex phenomenon. P. amarus is mostly grown as weed in agricultural and waste lands. It is a reputed plant used in Indian indigenous systems of medicine with hepatoprotective, diuretic, stomachic properties and is recently being used for the treatment of hepatitis B. The study revealed that Cd causes significant decrease in fresh and dry weight, length of root and shoot, protein, chlorophyll, carotenoids and sugar and increase in starch content. It is interesting to note that the therapeutically active compounds—phyllanthin and hypophyllanthin, enhanced at certain levels of Cd due to abiotic stress. Besides, the ultramorpholical changes were also observed in stomatal opening and wax deposition on both the surfaces of leaves. 相似文献
73.
Joanna Rutkowska Tomasz Wilk Mariusz Cichoń 《Behavioral ecology and sociobiology》2007,61(8):1211-1217
There is accumulating evidence that maternal hormones may play a role in offspring sex adjustment, but little is known about
the costs of such hormone-mediated mechanisms. Recent studies have reported sex-specific effects of hormones on offspring
viability. Specifically, we previously found that elevating the plasma androgen level in mothers results in a male-biased
offspring primary sex ratio, but it affects the viability of sons negatively and daughters positively in zebra finches (Taeniopygia guttata; Rutkowska and Cichoń, Anim Behav, 71:1283–1288, 2006). In this study, we studied further fitness consequences of exposure
to elevated yolk androgen levels in zebra finches. We measured growth rate and cellular immune response of nestlings that
hatched from eggs laid by females injected with testosterone during egg laying and nestlings of unaffected control females.
We found that sons of testosterone-treated females grew slower in comparison to sons of control females. The significant interaction
between experimental group and offspring sex indicates that sons of testosterone-treated mothers suffered impaired immune
responsiveness while daughters seemed to benefit from elevated androgen level in terms of enhanced immune responsiveness.
We found no effects of androgens on offspring performance at adulthood—neither fecundity of females nor attractiveness of
males was affected. We conclude that the benefits of biasing sex ratio towards males by increasing androgen level in the yolk
may be limited due to negative effects on male offspring performance early in life. 相似文献
74.
Gabriele Gerlach Andrea Hodgins-Davis Bradley MacDonald Rebecca C. Hannah 《Behavioral ecology and sociobiology》2007,61(11):1765-1770
Zebrafish (Danio rerio) larvae prefer the olfactory cues of kin to non-kin. We examined the potential benefits of kin preference by comparing growth
rate, shoaling, and aggressive behavior in juvenile zebrafish housed in groups of either familiar kin or unfamiliar non-kin.
Over an observation period of 5 days, the animals grew 33% more in kin groups; however, neither shoaling nor the frequency
of aggressive interactions was different in groups of related versus unrelated individuals. Shoaling behavior increased with
increasing observation time and increasing age, while aggressive behavior remained the same. We conclude that associating
with kin probably creates a less stressful environment that allows for higher growth rates, which can lead to higher direct
fitness based on increased survival and earlier reproduction. Kin recognition leading to kin-structured groups may therefore
be under positive selection. 相似文献
75.
The reproductive cycles and abundance of the sympatric colonial ascidians Pycnoclavella brava, Pycnoclavella aurilucens and Pycnoclavella communis from two Northwestern Mediterranean sites over a period of 2.5 years are reported. The species showed some differences in
their biological patterns. Gonad maturation and larval brooding took place during autumn and early winter for P. communis, during spring for P. aurilucens and during late winter and spring for P. brava. Summer was found to be the unfavorable season for all species, and an aestivation period occurred in P. communis and P. brava. Maximum abundance for the three species was observed during winter. Growth rates of the most abundant species, P. communis, were also monitored and found to peak during the initial phases of reactivation after aestivation. Growth rates decreased
afterwards, becoming negative as water temperature started to increase after the winter minima. Reproductive activity and
growth rates for P. communis displayed a temporal lag that suggested partitioning of resources to either reproduction or growth in this species. 相似文献
76.
稀土金属离子对梨形四膜虫的24小时生长影响 总被引:1,自引:0,他引:1
应用4种方法(细胞直计计数法、中性红试验、重蛋白及核酸含量测定)研究不同浓度稀土金属离子La^2+、Sm^3+、Y^3+、Gd^3+处理24h后,对梨形四膜虫的生长影响,结果表明,在低浓度时La^3+、Sm^3+、Y^3+,对四膜虫具有刺激生长的作用。随着浓度的升高,4种稀土金属离子均表现出毒性效应;高浓度时,抑制生长艇特别明显。计算La^3+、Sm^3+、Y^3+、Gd^3+的半数抑制浓度(IC 相似文献
77.
Michelle Voyer Genevieve Quirk Alistair McIlgorm Kamal Azmi 《Journal of Environmental Policy & Planning》2018,20(5):595-616
The ‘Blue Economy’ is an increasingly popular term in modern marine and ocean governance. The concept seeks to marry ocean-based development opportunities with environmental stewardship and protection. Yet different actors are co-opting this term in competing, and often conflicting ways. Four conceptual interpretations of the Blue Economy are identified, through examination of dominant discourses within international Blue Economy policy documents and key ‘grey’ literature. The way the Blue Economy is enacted is also examined, through an analysis of the Blue Economy ‘in practice’, and the actors involved. Finally, the scope of the Blue Economy is explored, with a particular focus on which particular marine industries are included or excluded from different conceptualizations. This analysis reveals areas of both consensus and conflict. Areas of consensus reflect the growing trend towards commodification and valuation of nature, the designation and delimitation of spatial boundaries in the oceans and increasing securitization of the world's oceans. Areas of conflict exist most notably around a divergence in opinions over the legitimacy of individual sectors as components of the ‘Blue Economy’, in particular, carbon-intensive industries like oil and gas, and the emerging industry of deep seabed mining. 相似文献
78.
The luminescent bacteria test according to EN ISO 11348 is frequently applied in (eco) toxicity testing and is applicable for a huge variety of environmental and industrial samples. A big disadvantage of this method is the very short exposure time, which is expressed in a low sensitivity in regard to substances with a delayed effect. Chronic effects, i.e. interference with cell growth, cannot be assessed with this conventional standard method. The goal of this research was to develop an automated testing system for long term toxicity towards the luminescent bacteria Vibrio fischeri by implementing microtitration-based instrumentation. The optimized method, hereinafter referred to as “kinetic luminescent bacteria test”, can be described as a miniaturized combination of the conventional short-term luminescence inhibition test according to EN ISO 11348 and the Photobacterium phosphoreum growth inhibition test (DIN 38412-37). The validation procedure included the evaluation of six reference compounds (3,4-Dichloroaniline, 3,5-Dichlorophenol, Chloramphenicol, Streptomycin sulfate, Potassium dichromate, Zinc sulfate heptahydrate) and three different endpoints that are acute luminescence inhibition (acute LI) after 30 min, chronic luminescence inhibition (chronic LI) after 24 h and growth inhibition (GI) after 14 h. The optimized method allows the assessment of acute and chronic effects within one test, by what a misinterpretation of the toxicity of substances with delayed bacterial toxicity can be prevented, without abandoning most of the advantages of the conventional short-term test. Therefore, the kinetic luminescent bacteria test is exceptional as an initial screening test for environmental samples or substances with unknown (eco) toxicological characteristics. 相似文献
79.
本文以个体生活资源基本需求为计算单位,探讨四川省主要生态资源能承载多少人口,预测四川省人口发展与生态资源的关系.根据本文给出的计算结果,四川省耕地费源已经饱和,其复耕事较高尚能满足人口需求;牧草场资源超载,面临荒漠化威胁;森林资源较为丰富,能够满足人口发展需求;水资源与人口关系富足有余,但工业污水排放和上游水源保护仍需给予关注.面对这一现实,四川省要进一步推行控制人口增长的生育政策;保护现有耕地资源,发展生态农业;合理规划草场资源,科学发展畜牧业;合理开发森林蕴藏资源,坚持合理采伐;加强水利设施建设,防治水污染,确保水资源可持续利用. 相似文献
80.
Zuyin Chen Lihua Li Lichong Hao Yu Hong Wencai Wang 《Frontiers of Environmental Science & Engineering》2022,16(1):2