全文获取类型
收费全文 | 19806篇 |
免费 | 1523篇 |
国内免费 | 3244篇 |
专业分类
安全科学 | 3342篇 |
废物处理 | 545篇 |
环保管理 | 3215篇 |
综合类 | 11369篇 |
基础理论 | 1675篇 |
环境理论 | 10篇 |
污染及防治 | 1465篇 |
评价与监测 | 844篇 |
社会与环境 | 1195篇 |
灾害及防治 | 913篇 |
出版年
2024年 | 69篇 |
2023年 | 287篇 |
2022年 | 541篇 |
2021年 | 749篇 |
2020年 | 745篇 |
2019年 | 588篇 |
2018年 | 490篇 |
2017年 | 663篇 |
2016年 | 777篇 |
2015年 | 818篇 |
2014年 | 960篇 |
2013年 | 1170篇 |
2012年 | 1416篇 |
2011年 | 1546篇 |
2010年 | 1083篇 |
2009年 | 1188篇 |
2008年 | 873篇 |
2007年 | 1380篇 |
2006年 | 1350篇 |
2005年 | 1139篇 |
2004年 | 1019篇 |
2003年 | 925篇 |
2002年 | 826篇 |
2001年 | 702篇 |
2000年 | 648篇 |
1999年 | 598篇 |
1998年 | 412篇 |
1997年 | 338篇 |
1996年 | 225篇 |
1995年 | 216篇 |
1994年 | 177篇 |
1993年 | 162篇 |
1992年 | 126篇 |
1991年 | 64篇 |
1990年 | 44篇 |
1989年 | 24篇 |
1988年 | 33篇 |
1987年 | 21篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 21篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 17篇 |
1979年 | 17篇 |
1978年 | 7篇 |
1974年 | 11篇 |
1973年 | 8篇 |
1971年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
应用氢化物原子荧光法,测定鲤鱼肝脏中痕量Hg和As,该法具有原子吸收和原子发射光谱两种技术优势,同时它具有分析灵敏度高,干扰少,线性范围宽,可多元素同时测定等优点;在KBH4-酸还原体系中同时测定鱼肝中Hg和As,方法检出限分别为Hg:0.33ng/ml和As0.36ng/ml,线性范围分别为:0.1-2.0ng/ml和1.0-20.0ng/ml。加标回收率分别为Hg:96.0%和As:100.6%。分析结果可靠,方法令人满意,并适合大批量样品的分析。 相似文献
983.
为了解决高温高盐矿井水对碳钢管道和设备腐蚀问题,进行了缓蚀挂片试验,研究适应该类水质的缓蚀剂种类和最佳投加量。试验结果表明:软化剂氢氧化钙和碳酸钠对碳钢均有一定缓蚀效果.其平均缓蚀率分别为17.33%、57.46%。因此药剂软化过程同时达到防腐效果有限:单独投加缓蚀剂HEDP的缓蚀效果明显,其静态缓蚀率82.46%以上,动态缓蚀率76.45%:复合配方缓蚀剂的缓蚀效果最好,最佳配方为“有机膦酸一聚环氧琥珀酸一锌盐”或“有机膦酸一磺酸基团多元共聚物一锌盐”,在投加量80mg/L时动态缓蚀率接近90%。 相似文献
984.
以《量和单位》(GB3100—3102-1993)为依据,列举了各种常见的错误使用量和单位的名称和符号、量和单位非标准化的例子,对其进行了分析和探讨,提出标准化对策。 相似文献
985.
986.
鄂尔多斯作为典型资源型城市,资源性产业在国民经济中长期占据主导地位,因此节能减排任务十分艰巨。本文分析总结了“十一五”以来鄂尔多斯市节能减排取得的成效及采取的主要措施,并在此基础上提出了几点建议。 相似文献
987.
生态保护的重点是保护自然资源及由其组成的各类生态系统,预防环境污染和生态破坏,改善和恢复生态系统的环境功能,维护生态平衡。我县工业发展迅速,生态环境面临的压力不断加大,为改善其生态环境现状及存在问题,提出对策与建议,以实现全县经济社会的可持续发展。 相似文献
988.
989.
Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis (FO) membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic (alginate) fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter- current flow operation of FO membrane process. 相似文献
990.
A novel method based on the selective pressure of particle size (particle-size cultivation method, PSCM) was developed for the cultivation and operation of aerobic granular sludge in a continuous-flow reactor, and compared with the conventional method based on the selective pressure of settling velocity (settling-velocity cultivation method, SVCM). Results indicated that aerobic granules could be cultivated in continuous operation mode by this developed method within 14 days. Although in the granulation process, under particle-size selective pressure, mixed liquor suspended solids (MLSS) in the reactor fluctuated greatly and filamentous bacteria dominated the sludge system during the initial operation days, no obvious difference in profile was found between the aerobic granules cultivated by PSCM and SVCM. Moreover, aerobic granules cultivated by PSCM presented larger diameter, lower water content and higher specific rates of nitrification, denitrifieation and phosphorus removal, but lower settling velocity. Under long term operation of more than 30 days, aerobic granules in the continuous-flow reactor could remain stable and obtain good chemical oxygen demand (COD), NH4^+-N, total nitrogen (TN) and total phosphorus (TP) removal. The results indicate that PSCM was dependent on the cultivation and maintenance of the stability of aerobic granules in continuous-flow bioreactors. 相似文献