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991.
992.
993.
Paul J. Pickett 《Journal of the American Water Resources Association》1997,33(2):465-480
ABSTRACT: The Black River, a tributary of the Chehalis River in western Washington State, has a history of widespread low dissolved oxygen (DO), anoxia in some locations, and fish kills. As part of a Total Maximum Daily Load (TMDL) study, environmental data were collected during two summer dry seasons and simulations were conducted with the WASP5 model to assess the effect of biochemical oxygen demand ( BOD ), ammonia, and nutrient loads on DO in the Black River. DO levels were below the State water quality regulatory criterion of 8.0 mg/L in almost all locations during the study. The slow middle reach of the river showed stratified conditions, with anoxia in some of the deepest pools. Based on model simulations, DO was found to still fall below the 8.0 mg/L criterion in the entire mainstem under “natural” conditions, and eutrophication was identified as a potential problem in the middle reach. A TMDL was proposed for BOD and ammonia that would prevent significant degradation of DO in the Black River. To prevent eutrophic conditions in the Black River, a TMDL for total phosphorus was proposed that establishes a protective criterion of 0.05 mg/L for the middle river during the dry low-flow season. 相似文献
994.
Lawrence K. Wang George G. Peery 《Journal of the American Water Resources Association》1975,11(5):919-932
ABSTRACT: The most common disinfection method is chlorination, however, it has been known that the practice of chlorination for water treatment in the Mississippi River area has caused a significant increase in mortality. The objective of this research was to search for effective disinfectants to replace chlorine. Three cationic surfactants have been tested for their bactericidal properties under various conditions. It has been found that 1 mg of cetyldimethyl-benzylammonium chloride can destroy about 4500 coliforms in one liter water within 10 minutes, under neutral pH conditions and room temperature. Cationic quaternary ammonium compound, therefore, can be a potential candidate disinfectant for replacing chlorine when necessary. 相似文献
995.
996.
硝酸及氯离子对高温硝酸铵水溶液热危险性的影响研究 总被引:3,自引:1,他引:3
国内外学者对硝酸铵的危险性进行了大量的研究,而对其水溶液的危险性至今开展不多。笔者采用差示扫描量热仪(DSC)及全自动反应量热仪(RC1e)对高温状态下的硝酸铵水溶液的热分解危险性、杂质离子对其稳定性的影响进行了研究。纯硝酸铵和90%硝酸铵水溶液的DSC实验表明,90%硝酸铵溶液和分析纯硝酸铵具有相似的热爆炸危险;90%硝酸铵水溶液在140~180℃之间的RC1e试验表明:硝酸或氯离子单独存在时,对硝酸铵分解都有不同程度的抑制作用,而同时存在时则大大降低体系的热稳定性。该结果对保障硝酸铵在生产、使用过程中的安全具有重要的参考价值。 相似文献
997.
Comparative characterization of two natural humic acids in the Pearl River
Basin, China and their environmental implications 总被引:1,自引:0,他引:1
Juan Liu Jin Wang Yongheng Chen Holger Lippol Johanna Lippmann-Pipke 《环境科学学报(英文版)》2010,22(11):1695-1702
Two humic acids (HAs) were isolated from contaminated river sediments present under comparative conditions in the Pearl River
Basin, China. YFHA (the HA extracted at an open pyrite mining area in Yunfu) exhibited a lower absorption intensity for certain bands
in the Fourier transform infrared spectra, a lower E4/E6 value (the UV absorbances at 465 nm (E4) and 665 nm (E6)), a lower apparent
molecular weight, a lower polarity and a lower oxygen functionality in comparison with GZHA (the HA isolated at an urban living area
in Guangzhou). All these differences indicated a higher degree of humification of YFHA than GZHA. Overall, the enrichment patterns
of permanent heavy metals in the studied HAs were similar to those in corresponding sediments. In particular, YFHA exhibited high
enrichment of trace element Tl, a characteristic concomitant from the mining of the pyrite minerals. The adsorption isotherms of two
HAs for goethite and pyrolusite, two representative geological materials, conformed to the Langmuir equation. Based on the qualitative
relationships between the Langmuir constants of the adsorption isotherms and the chemical characteristics of HAs, the main mechanism
of HA adsorption on these materials was suggested to be hydrophobic interaction. This study highlighted the promising use of HA as a
peculiar bio-indicator of uncommon trace metal contaminations. The HA adsorption mechanism on representative geological materials
further provided a theoretical basis for the study on the unusual metal behavior in complex environmental settings. 相似文献
998.
以磷酸钠为电解液,采用微弧氧化技术在钛片上直接制备TiO2膜,利用溶胶-凝胶法和硝酸铁掺杂方法对该膜表面进行修饰处理,以罗丹明B溶液模拟废水来评价TiO2膜光催化降解水中有机污染物的能力。利用EDX对微弧氧化膜表面成分进行分析。实验结果表明:微弧氧化TiO2膜具有一定的光催化活性。溶胶-凝胶法负载TiO2且硝酸铁掺杂处理后可以使铁离子进入微弧氧化TiO2负载膜,改善膜的光催化性能。溶胶-凝胶法负载TiO2膜对废水的光催化降解效率由13.8%提高到42.5%;铁离子掺杂1%可以使负载TiO2膜对废水的光催化效率由42.5%提高到68.9%。 相似文献
999.
1000.
The anaerobic ammonium-oxidizing (ANAMMOX) bacteria were enriched from a sequencing batch biofilm reactor (SBBR). A
quantitative competitive polymerase chain reaction (QC-PCR) system was successfully developed to detect and quantify ANAMMOX
bacteria in environmental samples. For QC-PCR system, PCR primer sets targeting 16S ribosomal RNA genes of ANAMMOX bacteria
were designed and used. The quantification range of this system was 4 orders of magnitude, from 103 to 106 copies per PCR,
corresponding to the detection limit of 300 target copies per mL. A 312-bp internal standard was constructed, which showed very
similar amplification e ciency with the target amxC fragment (349 bp) over 4 orders of magnitude (103–106). The linear regressions
were obtained with R2 of 0.9824 for 103 copies, 0.9882 for 104 copies, 0.9857 for 105 copies and 0.9899 for 106 copies, respectively.
Using this method, ANAMMOX bacteria were quantified in a shortcut nitrification/denitrification-anammox system which was set for
piggery wastewater treatment. 相似文献