全文获取类型
收费全文 | 539篇 |
免费 | 64篇 |
国内免费 | 185篇 |
专业分类
安全科学 | 69篇 |
废物处理 | 9篇 |
环保管理 | 81篇 |
综合类 | 380篇 |
基础理论 | 69篇 |
污染及防治 | 71篇 |
评价与监测 | 45篇 |
社会与环境 | 50篇 |
灾害及防治 | 14篇 |
出版年
2023年 | 14篇 |
2022年 | 18篇 |
2021年 | 34篇 |
2020年 | 31篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 37篇 |
2016年 | 33篇 |
2015年 | 27篇 |
2014年 | 35篇 |
2013年 | 52篇 |
2012年 | 39篇 |
2011年 | 60篇 |
2010年 | 40篇 |
2009年 | 44篇 |
2008年 | 35篇 |
2007年 | 60篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 8篇 |
2000年 | 14篇 |
1999年 | 15篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有788条查询结果,搜索用时 296 毫秒
31.
近年来,中俄双方开展了对等联合监测,但由于国域差别,两个国家在一个项目上采取了不同的实验方法,常出现同一个样品中俄双方出现不同的实验结果,为避免分歧,我国在少数几个站进行了中俄双方实验方法的对比实验,现就水质中总磷的测定将两国的实验方法和实验结果进行了分析。 相似文献
32.
通过对燃煤量的调查结果和呼和浩特CO浓度值监测结果分析了CO排放源的分布特征和CO浓度的变化特征,得出高燃煤地区和采暖期CO浓度值较高但低于标准值。对CO中毒事件案例与气象条件关系进行了分析得出逆温、高湿、小风和低气压时不利于一氧化碳浓度扩散,容易引起一氧化碳中毒事件的发生。 相似文献
33.
Does safety climate moderate the influence of staffing adequacy and work conditions on nurse injuries? 总被引:1,自引:0,他引:1
Mark BA Hughes LC Belyea M Chang Y Hofmann D Jones CB Bacon CT 《Journal of Safety Research》2007,38(4):431-446
PROBLEM: Hospital nurses have one of the highest work-related injury rates in the United States. Yet, approaches to improving employee safety have generally focused on attempts to modify individual behavior through enforced compliance with safety rules and mandatory participation in safety training. We examined a theoretical model that investigated the impact on nurse injuries (back injuries and needlesticks) of critical structural variables (staffing adequacy, work engagement, and work conditions) and further tested whether safety climate moderated these effects. METHOD: A longitudinal, non-experimental, organizational study, conducted in 281 medical-surgical units in 143 general acute care hospitals in the United States. RESULTS: Work engagement and work conditions were positively related to safety climate, but not directly to nurse back injuries or needlesticks. Safety climate moderated the relationship between work engagement and needlesticks, while safety climate moderated the effect of work conditions on both needlesticks and back injuries, although in unexpected ways. DISCUSSION AND IMPACT ON INDUSTRY: Our findings suggest that positive work engagement and work conditions contribute to enhanced safety climate and can reduce nurse injuries. 相似文献
34.
XIE Jian-jun YANG Xue-min ZHANG Lei DING Tong-li SONG Wen-li LIN Wei-gang 《环境科学学报(英文版)》2007,19(1):109-116
This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed. 相似文献
35.
Characterizing ionic species in PM2:5 and PM10 in four Pearl River Delta cities,
South China 总被引:8,自引:0,他引:8
PM_(2.5)and PM_(10)samples were collected at four major cities in the Pearl River Delta(PRD),South China,during winter and summer in 2002.Six water-soluble ions,Na~ ,NH_4~ ,K~ ,Cl~-,NO_3~- and SO_4~(2-)were measured using ion chromatography.On average,ionic species accounted for 53.3% and 40.5% for PM_(2.5)and PM_(10),respectively in winter and 39.4% and 35.2%,respectively in summer. Secondary ions such as sulfate,nitrate and ammonium accounted for the major part of the total ionic species.Sulfate was the most abundant species followed by nitrate.Overall,a regional pollution tendency was shown that there were higher concentrations of sulfate, nitrate and ammonium in Guangzhou City than those in the other PRD cities.Significant seasonal variations were also observed with higher levels of species in winter but lower in summer.The Asian monsoon system was favorable for removal and diffusion of air pollutants in PRD in summer while highly loading of local industrial emissions tended to deteriorate the air quality as well.NO_3~-/SO_4~(2-) ratio indicated that mobile sources have considerably contribution to the urban aerosol,and stationary sources should not be neglected. Besides the primary emissions,complex atmospheric reactions under favorable weather conditions should be paid more attention for the control of primary emission in the PRD region. 相似文献
36.
枯草芽孢杆菌对微污染水体的净化作用 总被引:5,自引:0,他引:5
采用投加枯草芽孢杆菌的水质净化方法,系统考察了在典型南方夏季气温下,封闭的模拟微污染水枯草芽孢杆菌净化体系中,投菌浓度、主要环境条件(pH和溶解氧)及其冲击对净化效果的影响.结果表明,枯草芽孢杆菌的最佳投菌浓度为3.2×105cfu·mL-1,适宜的环境条件为:pH5~7,溶解氧4~6mg·L-1.投菌9d后,CODM... 相似文献
37.
38.
The toxicity of naphthalene to a freshwater microalga, Chlorella pyrenoidosa, and the subsequent recovery of algae from the damage
were investigated under two nutrient conditions, either enriched with nitrogen (N) and phosphorus (P), or starved of N and P. Results
showed that C. pyrenoidosa was more sensitive to naphthalene under N,P-enriched condition, and the inhibitory rate generally increased
at first and then decreased gradually with the evaporation of naphthalene under both nutrient conditions. Enriched N, P reduced the
inhibitory rate at initial naphthalene concentration of 5 and 10 mg/L, but enhanced it at 100 mg/L, at which more severe ultrastructure
damages were found than those under N,P-starved condition. Observed damages included partly or totally disappearance of nucleolus,
nuclear, and plasma membranes. According to the chlorophyll content and cell density measurements, C. pyrenoidosa could recover
from naphthalene damage with initial concentrations 6 50 mg/L in 7 days under both nutrient conditions, while they could not recover
if the initial concentration of naphthalene was at 100 mg/L. Under the N,P-starved condition, the inability of C. pyrenoidosa to recover
from the naphthalene damage was consistent with the results of high inhibitory rate, low value of specific growth rate (SGR, 0.05
day??1), and the severe destruction of cell structure. However, under the N,P-enriched conditions, the observed lower inhibitory rate,
higher value of SGR (0.55 day??1), and the intact cell structure of most cells suggested that algae could potentially recover from the
naphthalene damage. 相似文献
39.
We assessed the ability of the MM5/CMAQ model to predict ozone (O3) air quality over the Kanto area and to investigate the factors
that a ect simulation of O3. We find that the coupled MM5/CMAQ model is a useful tool for the analysis of urban environmental
problems. The simulation results were compared with observational data and were found to accurately replicate most of the important
observed characteristics. The initial and boundary conditions were found to have a significant e ect on simulated O3 concentrations.
The results show that on hot and dry days with high O3 concentration, the CMAQ model provides a poor simulation of O3 maxima when
using initial and boundary conditions derived from the CMAQ default data. The simulation of peak O3 concentrations is improved with
the JCAP initial and boundary conditions. On mild days, the default CMAQ initial and boundary conditions provide a more realistic
simulation. Meteorological conditions also have a strong impact on the simulated distribution and accumulation of O3 concentrations
in this area. Low O3 concentrations are simulated during mild weather conditions, and high concentrations are predicted during hot
and dry weather. By investigating the e ects of di erent meteorological conditions on each model process, we find that advection and
di usion di er the most between the two meteorological regimes. Thus, di erences in the winds that govern the transport of O3 and its
precursors are likely the most important meteorological drivers of ozone concentration over the central Kanto area. 相似文献
40.