全文获取类型
收费全文 | 2436篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 44篇 |
废物处理 | 87篇 |
环保管理 | 143篇 |
综合类 | 759篇 |
基础理论 | 430篇 |
环境理论 | 7篇 |
污染及防治 | 735篇 |
评价与监测 | 137篇 |
社会与环境 | 104篇 |
灾害及防治 | 6篇 |
出版年
2022年 | 36篇 |
2021年 | 31篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 55篇 |
2017年 | 57篇 |
2016年 | 77篇 |
2015年 | 44篇 |
2014年 | 89篇 |
2013年 | 145篇 |
2012年 | 66篇 |
2011年 | 125篇 |
2010年 | 77篇 |
2009年 | 84篇 |
2008年 | 119篇 |
2007年 | 110篇 |
2006年 | 92篇 |
2005年 | 87篇 |
2004年 | 63篇 |
2003年 | 58篇 |
2002年 | 61篇 |
2001年 | 64篇 |
2000年 | 40篇 |
1999年 | 32篇 |
1998年 | 20篇 |
1997年 | 21篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 35篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1989年 | 13篇 |
1984年 | 14篇 |
1981年 | 17篇 |
1969年 | 14篇 |
1968年 | 13篇 |
1967年 | 16篇 |
1966年 | 24篇 |
1965年 | 29篇 |
1964年 | 18篇 |
1963年 | 26篇 |
1962年 | 23篇 |
1961年 | 31篇 |
1960年 | 21篇 |
1959年 | 21篇 |
1958年 | 14篇 |
1957年 | 25篇 |
1956年 | 16篇 |
1955年 | 16篇 |
排序方式: 共有2452条查询结果,搜索用时 437 毫秒
981.
The concentration of dissolved reactive phosphorus (DRP) in rivers can change intermittently within minutes depending on the weather and water discharge (Q), or activities in the watershed. Accordingly, accurate estimation of the annual DRP load requires frequent sampling or even continuous monitoring, which is laborious and cost-intensive. We present the design and laboratory evaluation of a new, robust, low-cost, low-tech device based on passive samplers (P-traps). The traps use Fe-(oxy)hydroxide coated quartz sand as an adsorbent enclosed in a vertical grid of individual cells separated from the river water by filter membranes. They are inexpensive, easy to handle, resistant to repeated desiccation and immersion and exposable for several months. They permit estimation of discharge dependent time weighted average DRP concentrations (C-Q relationships) and annual P loads of rivers characterized by highly variable DRP concentrations with a relative accuracy of +/- 3%. 相似文献
982.
Gilles Durrieu Quang-Khoai Pham Anne-Sophie Foltête Valérie Maxime Ion Grama Véronique Le Tilly Hélène Duval Jean-Marie Tricot Chiraz Ben Naceur Olivier Sire 《Environmental monitoring and assessment》2016,188(7):401
Water quality can be evaluated using biomarkers such as tissular enzymatic activities of endemic species. Measurement of molluscs bivalves activity at high frequency (e.g., valvometry) during a long time period is another way to record the animal behavior and to evaluate perturbations of the water quality in real time. As the pollution affects the activity of oysters, we consider the valves opening and closing velocities to monitor the water quality assessment. We propose to model the huge volume of velocity data collected in the framework of valvometry using a new nonparametric extreme values statistical model. The objective is to estimate the tail probabilities and the extreme quantiles of the distribution of valve closing velocity. The tail of the distribution function of valve closing velocity is modeled by a Pareto distribution with parameter ??t,τ, beyond a threshold τ according to the time t of the experiment. Our modeling approach reveals the dependence between the specific activity of two enzymatic biomarkers (Glutathione-S-transferase and acetylcholinesterase) and the continuous recording of oyster valve velocity, proving the suitability of this tool for water quality assessment. Thus, valvometry allows in real-time in situ analysis of the bivalves behavior and appears as an effective early warning tool in ecological risk assessment and marine environment monitoring. 相似文献
983.
984.
985.
An analysis of seismic risk from a tourism point of view 总被引:1,自引:0,他引:1
Mäntyniemi P 《Disasters》2012,36(3):465-476
Global awareness of natural calamities increased after the destructive Indian Ocean tsunami of December 2004, largely because many foreigners lost their lives, especially in Thailand. This paper explores how best to communicate the seismic risk posed by different travel destinations to crisis management personnel in tourists' home countries. The analysis of seismic risk should be straightforward enough for non-specialists, yet powerful enough to identify the travel destinations that are most at risk. The output for each location is a point in 3D space composed of the natural and built-up environment and local tourism. The tourism-specific factors can be tailored according to the tourists' nationality. The necessary information can be collected from various directories and statistics, much of it available over the Internet. The output helps to illustrate the overall seismic risk conditions of different travel destinations, allows for comparison across destinations, and identifies the places that are most at risk. 相似文献
986.
Juha Keränen Heidi Ahkola Juha Knuutinen Sirpa Herve Marko Reinikainen Jaana Koistinen 《Environmental science and pollution research international》2013,20(11):8001-8012
The formation of perfluorooctanoate (PFOA) from 1H,1H,2H,2H-perfluorodecanol (8:2 FTOH) was studied for the first time in laboratory experiments with brackish water. The water samples were collected from the Baltic Sea, which is one of the largest brackish water areas in the world and is polluted with PFOA and other perfluorinated compounds. The formation of PFOA was studied in closed-bottle experiments at different water temperatures. As a reference experiment, a modified OECD 310 test was conducted with sludge from a wastewater treatment plant and with brackish water. The PFOA and 8:2 FTOH were concentrated from water samples by solid-phase extraction (SPE) and were analysed using liquid chromatography–mass spectrometry. The effect of oxygen concentration on the formation of PFOA was studied using surface water samples with high and low oxygen contents. Other experiments were performed with oxygen-rich surface water and oxygen-deficient bottom water. The formation of PFOA was observed in all experiments; it was higher in the trial performed with brackish water than in the reference test carried out with sludge. Clear temperature dependence was observed in the formation of PFOA in brackish water tests; after a 30-day test period, a sixfold increase was observed in the amount of PFOA in surface water between the temperatures of 15 and 20 °C. Microbes were suggested as the major cause of the formation of PFOA, but other environmental characteristics, such as oxygen, could also affect the formation potential of PFOA. 相似文献
987.
Tuula Pellikka Tuula Kajolinna Miia Perälä 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1122-1131
EN 14791 is a European Standard Reference method for the measurement of SO2 in emissions. This standard is based on a wet-chemical method in which SO2 present in flue gases is absorbed into an absorption solution containing hydrogen peroxide, and analyzed as sulfates after sampling. This study presents the results obtained when three portable automated measuring systems (P-AMS), based on Fourier-transform infrared (FTIR) spectroscopy, non-dispersive infrared (NDIR) and ultraviolet-fluorescence (UV) techniques, were compared to the Standard Reference Method for SO2 (EN 14791) in order to verify whether they could be used as alternative methods (AM) to EN 14791. In the case of FTIR, the measurements were performed from hot and wet gas, without any conditioning. UV-fluorescence analyzers were equipped with dilution probes and one NDIR applied a permeation dryer, whereas the other had a chiller. Tests were carried out at concentration ranges from 0 to 200 mg/m3(n) and from 0 to 800 mg/m3(n) for testing of equivalency according to CEN/TS 14793 using a test bench. Equivalency test criteria were met for all tested P-AMS except for NDIR at the lower range. The SO2 results measured with NDIR and the chiller were lower compared to the set-up with NDIR and permeation. This was most probably due to the chiller causing absorption of SO2 in the condensate. Tests were also carried out at field conditions, measuring the SO2 emissions from a boiler combusting mainly bark. The same phenomena were observed in these tests as during the test bench study, i.e. the measurement set-up with NDIR and the chiller gave the lowest results. These data demonstrated that the tested alternative methods (FTIR, UV-fluorescence, and NDIR) could be used instead of the standard reference method EN 14791, thus providing real-time calibration of automated measuring systems. It must however be emphasized that when measuring water-soluble gases, such as SO2, the choice of suitable conditioning technique is critical in order to minimize losses of the studied component in the condensate.Implications: Portable automated measuring systems (P-AMS) provide real-time information about emissions and their concentrations, thus offering significant advantages compared to wet-chemical methods. This study presents results which can be used as a validation protocol to show that the tested P-AMS techniques (FTIR, NDIR, UV-fluorescence) could be used instead of EN 14791 (CEN 2017a) as alternative methods (AM), when paying attention to the selection of an appropriate conditioning technique. 相似文献
988.
Martin Röösli Charlotte Braun-Fährlander Nino Künzli Lucy Oglesby Gaston Theis Markus Camenzind 《Journal of the Air & Waste Management Association (1995)》2013,63(7):1115-1124
ABSTRACT The spatial variability of different fractions of particulate matter (PM) was investigated in the city of Basel, Switzerland, based on measurements performed throughout 1997 with a mobile monitoring station at six sites and permanently recorded measurements from a fixed site. Additionally, PM10 measurements from the following year, which were concurrently recorded at two urban and two rural sites, were compared. Generally, the spatial variability of PM4, PM10, and total suspended particulates (TSP) within this Swiss urban environment (area = 36 km2) was rather limited. With the exception of one site in a street canyon next to a traffic light, traffic density had only a weak tendency to increase the levels of PM. Mean PM10 concentration at six sites with different traffic densities was in the range of less than ±10% of the mean urban PM10 level. However, comparing the mean PM levels on workdays to that on weekends indicated that the impact of human activities, including traffic, on ambient PM levels may be considerable. Differences in the daily PM10 concentrations between urban and more elevated rural sites were strongly influenced by the stability of the atmosphere. In summer, when no persistent surface inversions exist, differences between urban and rural sites were rather small. It can therefore be concluded that spatial variability of annual mean PM concentration between urban and rural sites in the Basel area may more likely be caused by varying altitude than by distance to the city center. 相似文献
989.
Abstract Female mice were given 100 mg HCB/kg body weight i.p. and fed diets containing 0, 2.5, 5.0, and 7.5% of squalane. After 3 weeks samples of livar, blood and abdominal fat ware analysed for HCB as well as for squalane. HCB concentrations were significantly lowered as comoared to controls in all tissues and at all dietary concentrations of squalane to a maximum of about 36% in fat, 44% in liver and 47% in blood. The effect of squalane upon HCB concentrations was strongly dose depedent in abdominal fat. In contrast, no significant differences were seen with liver and blood between animals fed 5.0 or 7.5% of squalane. Squalane was detected in considerable amounts in the livers (50–100 ppm) but r.ct in abdominal fat (<1 ppm) of mice fed squalane. 相似文献
990.
Amanda Ode Lars Rylander Christian H. Lindh Karin Källén Bo A. G. Jönsson Peik Gustafsson Per Olofsson Sten A. Ivarsson Anna Rignell-Hydbom 《Environmental science and pollution research international》2013,20(11):7970-7978
In recent years, some perfluorinated compounds (PFCs) have been identified as potentially hazardous substances which are harmful to the environment and human health. According to limited data, PFC levels in humans could be influenced by several determinants. However, the findings are inconsistent. In the present study, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were measured in paired maternal and cord serum samples (N?=?237) collected between 1978 and 2001 in Southern Sweden to study the relationship between these and to investigate several potential determinants of maternal and fetal exposure to PFCs. Time trends of PFCs in Swedish women were also evaluated. The study is a part of the Fetal Environment and Neurodevelopment Disorders in Epidemiological Research project. PFOS, PFOA, and PFNA levels (median) were higher in maternal serum (15, 2.1, and 0.24 ng/ml, respectively) than in cord serum (6.5, 1.7, and 0.20 ng/ml, respectively). PFC levels were among the highest in women originating from the Nordic countries and the lowest in women from the Middle East, North Africa, and sub-Saharan Africa. Multiparous women had lower serum PFOA levels (1.7 ng/ml) than primiparous women (2.4 ng/ml). Maternal age, body mass index, cotinine levels, and whether women carried male or female fetuses did not affect serum PFC concentrations. Umbilical cord serum PFC concentrations showed roughly similar patterns as the maternal except for the gestational age where PFC levels increased with advancing gestational age. PFOS levels increased during the study period in native Swedish women. In summary, PFOS levels tend to increase while PFOA and PFNA levels were unchanged between 1978 and 2001 in our study population. Our results demonstrate that maternal country of origin, parity, and gestational age might be associated with PFC exposure. 相似文献