全文获取类型
收费全文 | 23356篇 |
免费 | 862篇 |
国内免费 | 4853篇 |
专业分类
安全科学 | 1289篇 |
废物处理 | 1515篇 |
环保管理 | 2476篇 |
综合类 | 8998篇 |
基础理论 | 5242篇 |
环境理论 | 2篇 |
污染及防治 | 5820篇 |
评价与监测 | 1652篇 |
社会与环境 | 1475篇 |
灾害及防治 | 602篇 |
出版年
2024年 | 30篇 |
2023年 | 224篇 |
2022年 | 699篇 |
2021年 | 578篇 |
2020年 | 542篇 |
2019年 | 436篇 |
2018年 | 1954篇 |
2017年 | 1960篇 |
2016年 | 1755篇 |
2015年 | 913篇 |
2014年 | 1094篇 |
2013年 | 1421篇 |
2012年 | 1724篇 |
2011年 | 2618篇 |
2010年 | 1733篇 |
2009年 | 1611篇 |
2008年 | 1926篇 |
2007年 | 2136篇 |
2006年 | 819篇 |
2005年 | 609篇 |
2004年 | 486篇 |
2003年 | 546篇 |
2002年 | 523篇 |
2001年 | 373篇 |
2000年 | 368篇 |
1999年 | 295篇 |
1998年 | 293篇 |
1997年 | 271篇 |
1996年 | 251篇 |
1995年 | 191篇 |
1994年 | 134篇 |
1993年 | 134篇 |
1992年 | 121篇 |
1991年 | 82篇 |
1990年 | 55篇 |
1989年 | 26篇 |
1988年 | 30篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 25篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
811.
This work was designed to explore the characteristics of photodegradation of herbicides in the copper-polluted water body. The
results showed that Cu(II) alone could induce a photo Fenton-like reaction to enhance the degradation of atrazine, in which hydroxyl
radical ( OH) was a main active species. Humic acids restrained atrazine degradation, nevertheless, when introducing Cu(II), the
photodegradation was accelerated, in which singlet oxygen (1O2) replaced OH acting as the prevailing species. A feasible mechanism
for the photochemical process was also proposed, which is helpful for better understanding the environmental photochemistry of
atrazine in the copper-polluted water. 相似文献
812.
The competition between submersed plants has been recognized as an important factor influencing the structure of plant communities
in shallow lakes. The ability of different species to take up and store nutrients from the surrounding ambience varies, and hence plant
community structure might be expected to affect the cycling of nutrients in lake ecosystems. In this study, the uptake of phosphorus
by Hydrilla verticillata and Vallisneria natans was studied and compared in monoculture and competitive mixed-culture plantings.
Results showed that for both studied species the phosphorus concentrations of different tissues and of whole plants was unaffected by
competition. However, the quantity of phosphorus accumulated by whole plants of H. verticillata was significantly higher in mixture
culture than in monoculture, while that of V. natans was lower in the mixed culture. The results indicated that H. verticillata has a
competitive advantage over V. natans, when the two species are grown in competition, and is able to accumulate a greater quantity of
phosphorus. 相似文献
813.
Cleaning of hollow-fibre polyvinyl chloride (PVC) membrane with di erent chemical reagents after ultrafiltration of algal-rich
water was investigated. Among the tested cleaning reagents (NaOH, HCl, EDTA, and NaClO), 100 mg/L NaClO exhibited the best
performance (88.4% 1.1%) in removing the irreversible fouling resistance. This might be attributed to the fact that NaClO could
eliminate almost all the major foulants such as carbohydrate-like and protein-like materials on the membrane surface, as confirmed by
Fourier transform infrared spectroscopy analysis. However, negligible irreversible resistance (1.5% 1.0%) was obtained when the
membrane was cleaning by 500 mg/L NaOH for 1.0 hr, although the NaOH solution could also desorb a portion of the major foulants
from the fouled PVC membrane. Scanning electronic microscopy and atomic force microscopy analyses demonstrated that 500 mg/L
NaOH could change the structure of the residual foulants on the membrane, making them more tightly attached to the membrane
surface. This phenomenon might be responsible for the negligible membrane permeability restoration after NaOH cleaning. On the
other hand, the microscopic analyses reflected that NaClO could e ectively remove the foulants accumulated on the membrane surface. 相似文献
814.
Polyaspartic acid (PASP) has been extensively studied in recent years as a green scale inhibitor. PASP was synthesized by thermal polycondensation of maleic anhydride and ammonium carbonate in this study. The optimal polycondensation reaction conditions were the raw material (maleic anhydride and ammonium carbonate) molar ratio of 1.0:1.2, the polymerization temperature of 180°C and reaction time of 2.0 hr. The results showed that PASP exhibits very good scale inhibiting performance. The inhibition rate was 95% for calcium carbonate and 90% for calcium sulfate by the application of 5 mg/L PASP. 相似文献
815.
微波酸活化粉煤灰吸附酸性大红染料废水实验研究 总被引:3,自引:0,他引:3
以微波酸活化改性后的粉煤灰为吸附剂,对酸性大红染料废水进行吸附脱色处理,考察了吸附时间、pH值、吸附剂投加量等对吸附脱色效果的影响。在酸性大红染料溶液初始浓度为100 mg/L、pH=5、活化粉煤灰投加量为10 g/L吸附1 h时,活化粉煤灰对酸性大红的脱色效果较好,去除率可达96%。对实验数据进行相关数学模型拟合,结果表明微波酸活化改性后的粉煤灰吸附去除酸性大红的等温吸附平衡符合Langmuir吸附等温式,改性前后的吸附过程动力学符合准二级吸附动力学模型,线性相关系数良好。 相似文献
816.
817.
818.
819.
820.
质量控制是贯穿环境监测全过程的技术手段和管理程序,文章通过对建设项竣工验收监测质量控制进行阐述,其目的是为了提高我们的监测水平和能力,更好的保护好我们的生态环境。 相似文献