收费全文 | 15776篇 |
免费 | 600篇 |
国内免费 | 6137篇 |
安全科学 | 992篇 |
废物处理 | 986篇 |
环保管理 | 1285篇 |
综合类 | 8676篇 |
基础理论 | 2764篇 |
环境理论 | 2篇 |
污染及防治 | 5986篇 |
评价与监测 | 611篇 |
社会与环境 | 541篇 |
灾害及防治 | 670篇 |
2024年 | 8篇 |
2023年 | 241篇 |
2022年 | 727篇 |
2021年 | 587篇 |
2020年 | 451篇 |
2019年 | 463篇 |
2018年 | 575篇 |
2017年 | 711篇 |
2016年 | 854篇 |
2015年 | 1070篇 |
2014年 | 1226篇 |
2013年 | 1711篇 |
2012年 | 1341篇 |
2011年 | 1449篇 |
2010年 | 1039篇 |
2009年 | 1021篇 |
2008年 | 1078篇 |
2007年 | 975篇 |
2006年 | 883篇 |
2005年 | 653篇 |
2004年 | 451篇 |
2003年 | 570篇 |
2002年 | 524篇 |
2001年 | 439篇 |
2000年 | 468篇 |
1999年 | 504篇 |
1998年 | 438篇 |
1997年 | 375篇 |
1996年 | 346篇 |
1995年 | 298篇 |
1994年 | 244篇 |
1993年 | 206篇 |
1992年 | 161篇 |
1991年 | 97篇 |
1990年 | 73篇 |
1989年 | 57篇 |
1988年 | 49篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1966年 | 1篇 |
Nanoplastics are widely distributed in freshwater environments, but few studies have addressed their effects on freshwater algae, especially on harmful algae. In this study, the effects of polystyrene (PS) nanoplastics on Microcystis aeruginosa (M. aeruginosa) growth, as well as microcystin (MC) production and release, were investigated over the whole growth period. The results show that PS nanoplastics caused a dose-dependent inhibitory effect on M. aeruginosa growth and a dose-dependent increase in the aggregation rate peaking at 60.16% and 46.34%, respectively, when the PS nanoplastic concentration was 100 mg/L. This caused significant growth of M. aeruginosa with a specific growth rate up to 0.41 d?1 (50 mg/L PS nanoplastics). After a brief period of rapid growth, the tested algal cells steadily grew. In addition, the increase in PS nanoplastics concentration promoted the production and release of MC. When the PS nanoplastic concentration was 100 mg/L, the content of the intracellular (intra-) and extracellular (extra-) MC increased to 199.1 and 166.5 μg/L, respectively, on day 26, which was 31.4% and 31.1% higher, respectively, than the control. Our results provide insights into the action mechanism of nanoplastics on harmful algae and the potential risks to freshwater environments.
相似文献Animal manure is an important source of antibiotics and antibiotic resistance genes (ARGs) in the environment. However, the difference of antibiotic residues and ARG profiles in layer and broiler manure as well as their compost remains unexplored. In this study, we investigated the profiles of twelve antibiotics, seventeen ARGs, and class 1 integrase gene (intI1) in layer and broiler manure, and the corresponding compost at large-scale. Compared with layer manure, broiler manure exhibited approximately six times more residual tetracyclines, especially chlortetracycline. The relative abundances of qnrS and ermA genes in broiler manure were significantly higher than those in layer manure. The concentration of tetracyclines not only had a significantly positive correlation with tetracycline resistance genes (tetA and tetC) but was also positively correlated with quinolone resistance (qepA, qnrB, and qnrS) and macrolide resistance (ermA and ermT). Most ARGs in manure were reduced after composting. However, the relative abundance of sulfonamide resistance gene sul1 increased up to 2.41% after composting, which was significantly higher than that of broiler (0.41%) and layer (0.62%) manure. The associated bacterial community was characterized by high-throughput 16S rRNA gene sequencing. The relative abundances of thermophilic bacteria had significant positive correlations with the abundance of sul1 in compost. The composting has a significant impact on the ARG-associated gut microbes in poultry manure. Variation partitioning analysis indicated that the change of bacterial community compositions and antibiotics contributed partially to the shift in ARG profiles. The results indicate that at industry-scale production broiler manure had more antibiotics and ARGs than layer manure did, and composting decreased most ARG abundances in poultry manure except for sulfonamide resistance genes.
相似文献To examine pesticide mixture toxicity to aqueous organisms, we assessed the single and combined toxicities of thiamethoxam and other four pesticides (chlorpyrifos, beta-cypermethrin, tetraconazole, and azoxystrobin) to the rare minnow (Gobiocypris rarus). Data from 96-h semi-static toxicity assays of various developmental phases (embryonic, larval, juvenile, and adult phases) showed that beta-cypermethrin, chlorpyrifos, and azoxystrobin had the highest toxicities to G. rarus, and their LC50 values ranged from 0.0031 to 0.86 mg a.i. L?1, from 0.016 to 6.38 mg a.i. L?1, and from 0.39 to 1.08 mg a.i. L?1, respectively. Tetraconazole displayed a comparatively high toxicity, and its LC50 values ranged from 3.48 to 16.73 mg a.i. L?1. By contrast, thiamethoxam exhibited the lowest toxic effect with LC50 values ranging from 37.85 to 351.9 mg a.i. L?1. Rare minnow larvae were more sensitive than embryos to all the pesticides tested. Our data showed that a pesticide mixture of thiamethoxam–tetraconazole elicited synergetic toxicity to G. rarus. Moreover, pesticide mixtures containing beta-cypermethrin in combination with chlorpyrifos or tetraconazole also had synergetic toxicities to fish. The majority of pesticides are presumed to have additive toxicity, while our data emphasized that the concurrent existence of some chemicals in the aqueous circumstance could cause synergetic toxic effect, leading to severe loss to the aqueous environments in comparison with their single toxicities. Thence, the synergetic impacts of chemical mixtures should be considered when assessing the ecological risk of chemicals.
相似文献