全文获取类型
收费全文 | 1332篇 |
免费 | 156篇 |
国内免费 | 125篇 |
专业分类
安全科学 | 62篇 |
废物处理 | 61篇 |
环保管理 | 108篇 |
综合类 | 581篇 |
基础理论 | 281篇 |
污染及防治 | 362篇 |
评价与监测 | 38篇 |
社会与环境 | 42篇 |
灾害及防治 | 78篇 |
出版年
2024年 | 9篇 |
2023年 | 40篇 |
2022年 | 64篇 |
2021年 | 44篇 |
2020年 | 32篇 |
2019年 | 33篇 |
2018年 | 57篇 |
2017年 | 63篇 |
2016年 | 68篇 |
2015年 | 88篇 |
2014年 | 95篇 |
2013年 | 116篇 |
2012年 | 110篇 |
2011年 | 119篇 |
2010年 | 71篇 |
2009年 | 67篇 |
2008年 | 78篇 |
2007年 | 62篇 |
2006年 | 47篇 |
2005年 | 44篇 |
2004年 | 22篇 |
2003年 | 33篇 |
2002年 | 31篇 |
2001年 | 27篇 |
2000年 | 24篇 |
1999年 | 26篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
排序方式: 共有1613条查询结果,搜索用时 28 毫秒
971.
972.
Erica S. Nielsen Maria Beger Romina Henriques Kimberly A. Selkoe Sophie von der Heyden 《Conservation biology》2017,31(4):872-882
Growing threats to biodiversity and global alteration of habitats and species distributions make it increasingly necessary to consider evolutionary patterns in conservation decision making. Yet, there is no clear‐cut guidance on how genetic features can be incorporated into conservation‐planning processes, despite multiple molecular markers and several genetic metrics for each marker type to choose from. Genetic patterns differ between species, but the potential tradeoffs among genetic objectives for multiple species in conservation planning are currently understudied. We compared spatial conservation prioritizations derived from 2 metrics of genetic diversity (nucleotide and haplotype diversity) and 2 metrics of genetic isolation (private haplotypes and local genetic differentiation) in mitochondrial DNA of 5 marine species. We compared outcomes of conservation plans based only on habitat representation with plans based on genetic data and habitat representation. Fewer priority areas were selected for conservation plans based solely on habitat representation than on plans that included habitat and genetic data. All 4 genetic metrics selected approximately similar conservation‐priority areas, which is likely a result of prioritizing genetic patterns across a genetically diverse array of species. Largely, our results suggest that multispecies genetic conservation objectives are vital to creating protected‐area networks that appropriately preserve community‐level evolutionary patterns. 相似文献
973.
采用Ti/SnO2电极间接阳极氧化法处理直接深棕M和活性艳蓝KNR模拟染料废水,研究电解质种类、pH、电压、NaCl投加量及电解时间对其降解效果的影响;在最佳组合条件下,通过分析UV-Vis光谱以及降解过程中氮元素的存在形式,研究上述2种染料的降解规律。结果表明,在pH为3,电压20 V,NaCl投加量为2.5 g/L的条件下,电解30 min后,直接深棕M和活性艳蓝KNR的脱色率分别达到80%和95%,60 min后直接深棕M的COD去除率可达75%,活性艳蓝KNR的COD去除率达到90%;电解60 min后,直接深棕M的偶氮双键完全破坏,萘环和苯环结构被逐步降解,活性艳蓝KNR溶液电解2 min,其分子结构中的蒽醌共轭体系被破坏,随反应的进行,蒽醌结构逐渐被破坏,染料逐步降解。 相似文献
974.
Patrick Gautier Marco Barroca Sophie Bertrand Cyril Eraud Maria Gaillard Michael Hamman Sébastien Motreuil Gabriele Sorci Bruno Faivre 《Behavioral ecology and sociobiology》2008,62(7):1159-1166
Several environmental factors have been shown to shape the pattern of investment of carotenoids into the expression of sexual
signals. Surprisingly, the impact of the social environment has been neglected. If a carotenoid-based sexual trait is used
by females to choose a mate or by males to assess the quality of potential competitors for mates, males, in the presence of
females, should upregulate expression of the trait. We tested this hypothesis in male zebra finches that were housed either
with females or in a male-only social environment. Additionally, to investigate whether the social modulation of the expression
of a sexual trait depends on the physiological need of carotenoids, we challenged half of the males with Escherichia coli lipopolysaccharide (LPS). We found that the social environment modulated the expression of bill color, with males kept in
the presence of females harboring a redder bill at the end of the 3 weeks that the experiment lasted. Males injected with
LPS showed duller bill color regardless of the presence of females, and social interactions with females result in upregulated
bill color similarly for phosphate-buffered saline (PBS) and LPS males. Thus, social environment and immune activation had
an additive effect on the expression of bill color. The effect of social environment on plasma carotenoids was less clear.
Indeed, a first replicate of the entire experiment showed that both immune challenge and social context affected bill color,
with a negative effect of immune challenge and a positive effect of the presence of females on circulating carotenoids. However,
a second replicate of the experiment showed only a negative effect of the immune challenge. These results, therefore, suggest
that the social environment can affect the expression of carotenoid-based sexual traits under both benign and carotenoid-demanding
conditions. Whatever the signaling function of bill color (female mate choice or male–male competition for mates), the observed
flexibility may be adaptive because the expression of the signal can be modulated depending on the expected rewards or costs
associated with the presence or absence of females. Nevertheless, the mechanisms underlying such an effect are still unknown. 相似文献
975.
Jinhui Liang Yuchen Luo Benhang Li Shiqi Liu Liansheng Yang Peng Gao Li Feng Yongze Liu Ziwen Du Liqiu Zhang 《Frontiers of Environmental Science & Engineering》2022,16(10):126
976.
为了明确不同接种量的微生物秸秆腐熟剂对蔬菜副产物堆肥效果的影响,以玉米秸秆为调理剂,在调节初始物料含水率为63%和 C/N 为 28 的条件下,设置了 B1(堆肥混合物+1%秸秆腐熟剂)、B2(堆肥混合物+3%秸秆腐熟剂)、B3(堆肥混合物+5%秸秆腐熟剂) 和 CK(堆肥混合物+3%灭菌惰性载体)4个处理,测定不同堆肥处理对温度、含水率、碳氮比(C/N)、半纤维素、纤维素、木质素、总养分含量、发芽指数等指标的影响.结果表明,蔬菜副产物堆肥接种微生物秸秆腐熟剂均能够使堆肥周期缩短,有效降低堆肥含水率,提高有机质的降解幅度,并且使堆肥中半纤维素、纤维素、木质素降解率分别提高1.03%、1.16%和1.47%;氮磷钾养分含量也比不接种处理平均提高0.48%.4 个处理的总体堆肥效果表现为:B2> B1> B3> CK. 相似文献
977.
连云港市水环境整治规划研究 总被引:3,自引:0,他引:3
本文在“控源导流”思想的指导下,根据连云港市水环境污染现状,提出了连云港市水环境整治规划方案,它包括蔷薇河水源保护工程、新沂河污水资源化生态工程、市区(新海地区)污水治理工程、石梁河水库水源保护工程和四县城区污水治理工程五大工程,试图根治连云港市水污染。 相似文献
978.
979.
We estimated the population sizes of the three species of columnar cacti that grow on the island of Curaçao using ground and aerial transects, and we examined the island's carrying capacity for two species of nectar-feeding bats that depend on nectar from the flowers of these cacti. We calculated carrying capacity based on the daily availability of mature flowers between January and December 1993 and the field energy requirements of bats as estimated from an equation for eutherian mammals (low estimate) and one for passerine birds (high estimate) based on body mass. Additional energy requirements of pregnancy and lactation were taken into account. We estimated that 461,172 columnar cacti were present on Curaçao (38% Subpilocereus repandus , 51% Stenocereus griseus , and 11% Pilosocereus lanuginosus ). May through September are the critical months when bats rely most heavily on cactus for food. July 1993 was a bottleneck with the smallest number of mature flowers per day. July and August were months of greatest energy demand because females were lactating. We estimate that the carrying capacity for Glossophaga longirostris in July, when the bat ( Leptonycteris curasoae ) population was 900, was near 1200, an estimate that fits the observed population size of nectar-feeding bats on the island. We suggest that the extensive removal of native vegetation occurring on Curaçao be strictly regulated because further destruction of the cacti will result in a decrease and potential loss of the already low populations of nectar-feeding bats. 相似文献
980.
Du Xiaohan Hou Yongjiang 《Environmental science and pollution research international》2023,30(5):11141-11174
Environmental Science and Pollution Research - Prussian blue analogs (PBAs), a type of metal–organic frameworks (MOFs), have attracted much attention because of their large specific surface... 相似文献