全文获取类型
收费全文 | 3339篇 |
免费 | 32篇 |
国内免费 | 174篇 |
专业分类
安全科学 | 96篇 |
废物处理 | 198篇 |
环保管理 | 291篇 |
综合类 | 596篇 |
基础理论 | 784篇 |
环境理论 | 2篇 |
污染及防治 | 1139篇 |
评价与监测 | 242篇 |
社会与环境 | 184篇 |
灾害及防治 | 13篇 |
出版年
2023年 | 17篇 |
2022年 | 70篇 |
2021年 | 39篇 |
2020年 | 24篇 |
2019年 | 37篇 |
2018年 | 117篇 |
2017年 | 51篇 |
2016年 | 76篇 |
2015年 | 85篇 |
2014年 | 90篇 |
2013年 | 270篇 |
2012年 | 89篇 |
2011年 | 158篇 |
2010年 | 139篇 |
2009年 | 156篇 |
2008年 | 161篇 |
2007年 | 188篇 |
2006年 | 142篇 |
2005年 | 117篇 |
2004年 | 147篇 |
2003年 | 140篇 |
2002年 | 115篇 |
2001年 | 239篇 |
2000年 | 143篇 |
1999年 | 71篇 |
1998年 | 41篇 |
1997年 | 48篇 |
1996年 | 34篇 |
1995年 | 42篇 |
1994年 | 43篇 |
1993年 | 42篇 |
1992年 | 30篇 |
1991年 | 35篇 |
1990年 | 27篇 |
1989年 | 34篇 |
1988年 | 20篇 |
1987年 | 17篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 18篇 |
1983年 | 22篇 |
1982年 | 22篇 |
1981年 | 16篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1975年 | 12篇 |
1973年 | 9篇 |
1972年 | 10篇 |
排序方式: 共有3545条查询结果,搜索用时 312 毫秒
521.
Scott W. Stine Inhong Song Christopher Y. Choi Charles P. Gerba 《Food and environmental virology》2011,3(2):86-91
The purpose of this study was to quantify the transfer of viral and bacterial pathogens in water used to dilute pesticides
sprayed onto the surfaces of cantaloupe, iceberg lettuce, and bell peppers. The average percent transfer of bacteria was estimated
to range from 0.00021 to 9.4%, while average viral transfer ranged from 0.055 to 4.2%, depending on the type of produce. Based
on these values the concentrations of hepatitis A virus (HAV) and Salmonella in water necessary to achieve a 1:10,000 annual risk of infection were calculated. Under worst case scenario assumptions,
in which a pesticide is applied on the same day that the produce is harvested and when maximum transfer values are used, concentrations
of 1.5 × 10−3 CFU Salmonella or 2.7 × 10−7 MPN HAV per 100 ml of the water used for application would result in 1:10,000 annual infection risk to anyone who consumes
the fresh produce. If harvesting does not occur until at least 14 days after the application, to produce the same risk of
infection, the numbers of Salmonella in 100 ml of water used to dilute the pesticides will be greater by up to five orders of magnitude, while the HAV numbers
will have increased by up to two orders of magnitude. Based on the reported concentrations of enteric viruses in surface and
ground waters in the United States, a 1:10,000 annual risk of infection could easily be exceeded with some groundwater sources
used in the United States. To reduce the risks associated with the consumption of fresh produce, water used to prepare pesticides
in spray applications should be evaluated for its microbiological quality. 相似文献
522.
523.
524.
The potential of a chlorophenol (CP)-adapted consortium to dechlorinate polychlorinated biphenyls (PCBs) in sewage sludge was investigated. Results show that dechlorination rates differed significantly depending on sludge source and PCB congener. Higher total solid concentrations in sewage sludge and higher concentrations of chlorine in PCB resulted in slower dechlorination rates. No significant difference was found for 2,3,4,5-CB dechlorination from pH 6.0 to pH 8.0; however, dechlorination did not occur at pH 9.0 during a 41-day incubation period. Results show that at concentrations of 1 to 10 mg/L, the higher the PCB concentration, the faster the dechlorination rate. In addition, dechlorination rates were in the following order: methanogenic conditions > sulfate-reducing conditions > denitrifying conditions. The addition of acetate, lactate, pyruvate, and ferric chloride decreased lag times and enhanced dechlorination; however, the addition of manganese dioxide had an inhibitory effect. Dechlorination rates were also enhanced by the addition of PCB congeners, including 2,3,4-CB, 2,3,4,5-CB and 2,3,4,5,6-CB in mixture. Overall results show that the CP-adapted consortium has the potential to enhance PCB dechlorination. The optimal dechlorination conditions presented in this paper may be used as a reference for feasibility studies of PCB removal from sludge. 相似文献
525.
The agricultural non-point source pollution by nitrogen (N) and phosphorus (P) loss from typical paddy soil (whitish soil, Bai Tu in Chinese) in the Taihu Lake region was investigated through a case study. Results shown that the net load of nutrients from white soil is 34.1 kg ha(-1) for total nitrogen (TN), distributed as 19.4 kg ha(-1), in the rice season and 14.7 kg ha(-1) in the wheat season, and for total phosphorus (TP) 1.75 kg ha(-1), distributed as 1.16 kg ha(-1) in the rice season and 0.58 kg ha(-1) in the wheat season. The major chemical species of N loss is different in the two seasons. NH4-N is main the form in the rice season (53% of TN). NO3-N is the main form in wheat season (46% of TN). Particle-P is the main form in both seasons, (about 56% of TP). The nutrient loss varied with time of the year. The main loss of nutrients happened in the 10 days after planting, 64% of TN and 42% of TP loss, respectively. Rainfall and fertilizer application are the key factors which influence nitrogen and phosphorus loss from arable land, especially rainfall events shortly after fertilizer application. So it is very important to improve the field management of the nutrients and water during the early days of planting. 相似文献
526.
Perfluorooctane sulfonate(PFOS) is a persistent organic pollutant(POP) and emergent contaminant that are widespread in the environment. Understanding the mechanisms controlling the distribution of PFOS and its isomers between hydrargillite and the water phase is important in order to study their redistribution and mobility in the environment. This study investigated the effects of pH, humic acid, fulvic acid and Na2SO4 on sorption of PFOS isomers to hydrargillite. A mixture... 相似文献
527.
528.
The pattern and characteristics of diving in 14 female northern rockhopper penguins, Eudyptes chrysocome moseleyi, were studied at Amsterdam Island (37°50′S; 77°31′E) during the guard stage, using electronic time–depth recorders. Twenty-nine
foraging trips (27 daily foraging trips and two longer trips including one night) with a total of 16 572 dives of ≥3 m were
recorded. Females typically left the colony at dawn and returned in the late afternoon, spending an average of 12 h at sea,
during which they performed ∼550 dives. They were essentially inshore foragers (mean estimated foraging range 6 km), and mainly
preyed upon the pelagic euphausiid Thysanoessa gregaria, fishes and squid being only minor components of the diet. Mean dive depth, dive duration, and post-dive intervals were 18.4 m
(max. depth 109 m), 57 s (max. dive duration 168 s), and 21 s (37% of dive duration), respectively. Descent and ascent rates
averaged 1.2 and 1.0 ms−1 and were, together with dive duration, significantly correlated with dive depth. Birds spent 18% of their total diving time
in dives reaching 15 to 20 m, and the mean maximum diving efficiency (bottom time:dive cycle duration) occurred for dives
reaching 15 to 35 m. The most remarkable feature of diving behaviour in northern rockhopper penguins was the high percentage
of time spent diving during daily foraging trips (on average, 69% of their time at sea); this was mainly due to a high dive
frequency (∼44 dives per hour), which explained the high total vertical distance travelled during one trip (18 km on average).
Diving activity at night was greatly reduced, suggesting that, as other penguins, E. chrysocome moseleyi are essentially diurnal, and locate prey using visual cues.
Received: 9 December 1998 / Accepted: 3 March 1999 相似文献
529.
530.
基于2013—2018年哈尔滨市气象数据、大气污染物数据和细颗粒物(PM2.5)中金属成分数据,采用机器学习方法探索大气PM2.5中金属浓度预测模型,并选择最优模型进行污染物浓度预测。结果表明,多元线性回归(MLR)、人工神经网络(BP-ANN)、支持向量机(SVM)和随机森林(RF)4种模型中,RF对大气PM2.5中5种金属[锑(Sb)、砷(As)、铅(Pb)、镉(Cd)、铊(Tl)]的浓度预测效果最佳,在训练集和测试集中表现均较稳定,其中相关系数(r)均>0.7, 平均绝对误差(MAE)和均方根误差(RMSE)数值较小。RF在大气PM2.5中金属浓度预测上具有较好的表现,可在缺乏监测和实验数据的情况下,实现对大气颗粒物中金属浓度的快速预测,为全面了解颗粒物中金属污染特征提供数据基础。 相似文献