全文获取类型
收费全文 | 7380篇 |
免费 | 628篇 |
国内免费 | 2035篇 |
专业分类
安全科学 | 1518篇 |
废物处理 | 159篇 |
环保管理 | 671篇 |
综合类 | 5310篇 |
基础理论 | 810篇 |
污染及防治 | 925篇 |
评价与监测 | 259篇 |
社会与环境 | 153篇 |
灾害及防治 | 238篇 |
出版年
2024年 | 74篇 |
2023年 | 213篇 |
2022年 | 288篇 |
2021年 | 376篇 |
2020年 | 275篇 |
2019年 | 333篇 |
2018年 | 212篇 |
2017年 | 224篇 |
2016年 | 287篇 |
2015年 | 333篇 |
2014年 | 653篇 |
2013年 | 400篇 |
2012年 | 525篇 |
2011年 | 613篇 |
2010年 | 588篇 |
2009年 | 405篇 |
2008年 | 456篇 |
2007年 | 390篇 |
2006年 | 363篇 |
2005年 | 831篇 |
2004年 | 442篇 |
2003年 | 346篇 |
2002年 | 284篇 |
2001年 | 235篇 |
2000年 | 185篇 |
1999年 | 119篇 |
1998年 | 93篇 |
1997年 | 104篇 |
1996年 | 72篇 |
1995年 | 66篇 |
1994年 | 59篇 |
1993年 | 46篇 |
1992年 | 36篇 |
1991年 | 39篇 |
1990年 | 36篇 |
1989年 | 33篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 829 毫秒
431.
Biosorption of silver ions onto Bacillus cereus biomass was investigated. Overall kinetic experiments were performed for the
determination of the necessary contact time for the attainment of equilibrium. It was found that the overall biosorption process was
best described by pseudo second-order kinetic model. The crystals detected by scanning electron microscope and X-ray photoelectron
spectroscopy suggested the precipitation was a possible mechanism of biosorption. The molecular genetics of silver resistance of B.
cereus biomass was also detected and illustrated by a whole cell sensor tool. 相似文献
432.
The nitrogen (N) biological cycle of the Suaeda salsa marsh ecosystem in the Yellow River estuary was studied during 2008 to 2009.
Results showed that soil N had significant seasonal fluctuations and vertical distribution. The N/P ratio (15.73±1.77) of S. salsa was
less than 16, indicating that plant growth was limited by both N and P. The N absorption coefficient of S. salsa was very low (0.007),
while the N utilization and cycle coefficients were high (0.824 and 0.331, respectively). The N turnover among compartments of S.
salsa marsh showed that N uptake from aboveground parts and roots were 2.539 and 0.622 g/m2, respectively. The N translocation
from aboveground parts to roots and from roots to soil were 2.042 and 0.076 g/m2, respectively. The N translocation from aboveground
living bodies to litter was 0.497 g/m2, the annual N return from litter to soil was far less than 0.368 g/m2, and the net N mineralization
in topsoil during the growing season was 0.033 g/m2. N was an important limiting factor in S. salsa marsh, and the ecosystem was
classified as unstable and vulnerable. S. salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat, and the
nutrient enrichment due to N import from the Yellow River estuary would be a potential threat to the S. salsa marsh. Excessive nutrient
loading might favor invasive species and induce severe long-term degradation of the ecosystem if human intervention measures were
not taken. The N quantitative relationships determined in our study might provide a scientific basis for the establishment of effective
measures. 相似文献
433.
Tao Zhang Qiucheng Li Lili Ding Hongqiang Ren Ke Xu Yonggang Wu Dong Sheng 《环境科学学报(英文版)》2011,23(6):881-890
Chemical precipitation to form magnesium ammonium phosphate (MAP) is an effective technology for recovering ammonium
nitrogen (NH4
+-N). In the present research, we investigated the thermodynamic modeling of the PHREEQC program for NH4
+-N
recovery to evaluate the effect of reaction factors on MAP precipitation. The case study of NH4
+-N recovery from coking wastewater
was conducted to provide a comparison. Response surface methodology (RSM) was applied to assist in understanding the relative
significance of reaction factors and the interactive effects of solution conditions. Thermodynamic modeling indicated that the saturation
index (SI) of MAP followed a polynomial function of pH. The SI of MAP increased logarithmically with the Mg2+/NH4
+ molar ratio
(Mg/N) and the initial NH4
+-N concentration (CN), respectively, while it decreased with an increase in Ca2+/NH4
+ and CO3
2??/NH4
+
molar ratios (Ca/N and CO3
2??/N), respectively. The trends for NH4
+-N removal at different pH and Mg/N levels were similar to the
thermodynamic modeling predictions. The RSM analysis indicated that the factors including pH, Mg/N, CN, Ca/N, (Mg/N) (CO3
2??/N),
(pH)2, (Mg/N)2, and (CN)2 were significant. Response surface plots were useful for understanding the interaction effects on NH4
+-N
recovery. 相似文献
434.
新年伊始,安徽省怀宁县发生血铅超标事件,引起广泛关注。近几年,血铅事件一次次牵动人们的神经。2009年发生了6起较大血铅事件, 相似文献
435.
436.
437.
438.
城市作为节能管理的基本行政单元,在国家节能战略和节能政策的实施中起承上启下的作用,而中国城市节能目标的制定缺乏定量分析工具、主观性强。“十一五”期间,地方政府为了完成节能目标,甚至出现了“拉闸限电”、“中止供暖”等极端节能现象,节能的社会成本偏高。另一方面,中国城市能源效率差异巨大。2009年在有观测值的214个城市中,单位GDP能耗平均值为1.43吨标煤/万元,最大的是石嘴山市的6.75吨标煤/万元,是均值的4.7倍;最小的是汕尾市的0.528吨标煤/万元,仅是均值的36.9%。“十二五”期间,为了完成国家节能任务,探索城市节能分类管理、科学化管理新机制至关重要。 相似文献
439.
440.
2010年,韶关市紧紧围绕创建“全国生态文明示范市”目标,采取加快经济发展方式转变、维护生态屏障、创建优美宜居乡村等措施,综合整治环境,还优美环境于民。加快经济发展方式转变大力发展生态经济,加快推进以资源高效利用和循环利用为核心、以“减量化、再利用、资源化”为原则的低消耗、低排放、高效率的经济增长模式, 相似文献