全文获取类型
收费全文 | 1135篇 |
免费 | 18篇 |
国内免费 | 23篇 |
专业分类
安全科学 | 36篇 |
废物处理 | 40篇 |
环保管理 | 246篇 |
综合类 | 138篇 |
基础理论 | 230篇 |
环境理论 | 2篇 |
污染及防治 | 372篇 |
评价与监测 | 69篇 |
社会与环境 | 38篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 31篇 |
2016年 | 31篇 |
2015年 | 21篇 |
2014年 | 34篇 |
2013年 | 180篇 |
2012年 | 49篇 |
2011年 | 47篇 |
2010年 | 51篇 |
2009年 | 62篇 |
2008年 | 48篇 |
2007年 | 61篇 |
2006年 | 71篇 |
2005年 | 42篇 |
2004年 | 31篇 |
2003年 | 33篇 |
2002年 | 35篇 |
2001年 | 7篇 |
2000年 | 16篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 18篇 |
1996年 | 7篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1972年 | 7篇 |
1967年 | 4篇 |
排序方式: 共有1176条查询结果,搜索用时 640 毫秒
841.
Measurements from sites of the Southeastern Aerosol Research and Characterization (SEARCH) program, made from 1998 to 2001, are used with a thermodynamic equilibrium model, Simulating Composition of Atmospheric Particles at Equilbrium (SCAPE2), to extend an earlier investigation of the responses of fine particulate nitrate (NO3-) and fine particulate matter (PM2.5) mass concentrations to changes in concentrations of nitric acid (HNO3) and sulfate (SO42-). The responses were determined for a projected range of variations of SO42- and HNO3 concentrations resulting from adopted and proposed regulatory initiatives. The predicted PM2.5 mass concentration decreases averaged 1.8-3.9 microg/m3 for SO42- decreases of 46-63% from current concentrations. Combining the S042- decrease with a 40% HNO3 decrease from current concentrations (approximating expected mobile-source oxides of nitrogen [NOx] reductions by 2020) yielded additional incremental reductions of mean predicted PM2.5 mass concentration of 0.2 microg/m3 for three nonurban sites and 0.8-1 microg/m3 for one nonurban and two urban sites. Increasing the HNO3 reduction to 55% (an estimate of adding Clear Skies Phase II NOx reductions) yielded additional incremental reductions of mean predicted PM2.5 mass concentration of 0-0.4 microg/m3. Because of the well-documented losses of particulate NO3- from Federal Reference Method (FRM) filters, only a fraction of these incremental changes would be observed. 相似文献
842.
843.
Glenn E. Palomaki George J. Knight James E. Haddow Jacob A. Canick Devereux N. Saller Jr Diane S. Panizza 《黑龙江环境通报》1992,12(11):925-930
Two prenatal centres in New England, routinely using a screening protocol for fetal Down syndrome that included maternal serum alpha-fetoprotein (AFP), unconjugated oestriol (uE3), and human chorionic gonadotropin (hCG) measurements in combination with maternal age, adopted a separate screening protocol for trisomy 18. That protocol identified a pregnancy as being at high risk when AFP, uE3, and hCG measurements all fell at or below specified cut-offs (0.75, 0.60, and 0.55 multiples of the median, respectively), regardless of maternal age. Among the first 19 491 women screened, 98 (0.5 per cent) were found to have values which placed them in the high-risk category. Four of these women were subsequently found not to be pregnant. In two others, samples from non-pregnant individuals were found to have been incorrectly submitted for analysis in place of the samples from the pregnant women. All of the remaining 92 women were counselled and offered amniocentesis and fetal karyotyping. Eighty-eight (96 per cent) accepted. Karyotypes or birth outcomes were available on all 92 pregnancies. Six cases of trisomy 18 and one case of Turner syndrome were identified by karyotype. One case of trisomy 18 was identified for every 14 unaffected pregnancies offered amniocentesis. In the present prospective study, an estimated 85 per cent of the cases of trisomy 18 were identified. However, given the small number ofcases (six), the 95 per cent confidence interval for the detection rate is broad (40–95 per cent). 相似文献
844.
Unconjugated oestriol (uE3) and human chorionic gonadotropin (hCG) levels were determined in second-trimester maternal serum (MS) samples from 21 pregnancies associated with fetal anencephaly and 15 pregnancies associated with fetal open spina bifida. Each measurement was expressed as a multiple of the median (MoM) for unaffected pregnancies for each completed week of gestation. In pregnancies associated with anencephaly, the median value for MSuE3 was very low (0–17 MoM, range <0·12–0·33 MoM), suggesting a functional defect in the fetal adrenal prior to 20 weeks' gestation; the median value for MShCG was also low (0–73 MoM), although not to the same extent as for MSuE3. A biological explanation for the hCG result is not apparent. In pregnancies associated with open spina bifida, the MSuE3 and MShCG values were unremarkable, consistent with a lack of involvement of these open fetal defects in the synthesis and secretion of uE3 and hCG. 相似文献
845.
Papadopoulos Aristotelis Parissopoulos George Papadopoulos Frantzis Papagianopoulou Areti Karteris Apostolos 《Water, Air, & Soil Pollution: Focus》2004,4(4-5):157-167
This paper presents a test case for the effects of recirculation on stabilization pond performance. The BOD5, COD, SS and Total Coliform removal at the intermediate treatment stages and the outlet of a stabilization pond treatment line, over a 2-year operational period (January 2000-December 2001), is described in detail and the effluent at different stages of treatment is compared to that of a conventional stabilization pond treatment line operating under similar conditions. The system consisted of four ponds in line—an anaerobic pond, followed by three individual ponds (Pond 1, Pond 2 and Pond 3). The effluent of the last pond (Pond 3) was recirculated back to the inlet of the first pond (Pond 1) at a discharge ratio 2:1 (recirculation:inflow). The overall BOD5, COD, SS and Total Coliforms total reduction was 89%, 81%, 85% and 99.7%, respectively. The anaerobic pond proved to be the most efficient in removing COD and SS (57% and 68%, respectively) whereas Pond 1 achieved the most significant reduction in BOD5 and Total Coliforms (69% and 86%, respectively). Although BOD5 and COD were adequately reduced by the recirculating pond line, the SS concentration was high due to algae presence in the final effluent. Moreover, the Total Coliforms were insufficiently removed due to the reduced hydraulic retention time involved in this type of recirculation. 相似文献
846.
Evan A. Howell Peter H. Dutton Jeffrey J. Polovina Helen Bailey Denise M. Parker George H. Balazs 《Marine Biology》2010,157(5):1011-1026
Satellite telemetry data from 17 juvenile loggerhead turtles (43.5–66.5 cm straight carapace length) were used in conjunction with oceanographic data to analyze the influence of regional and seasonal oceanography on dive behavior in the North Pacific Ocean. Combined dive behavior for all individuals showed that turtles spent more than 80% of their time at depths <5 m, and more than 90% of their time at depths <15 m. Multivariate classifications of dive data revealed four major dive types, three representing deeper, longer dives, and one representing shallower dives shorter in duration. Turtles exhibited variability in these dive types across oceanographic regions, with deeper, longer dives in the Hawaii longline swordfish fishing grounds during the first quarter of the year, as well as in the Kuroshio Extension Bifurcation Region and the region near the Baja California Peninsula, Mexico. Turtles in the Kuroshio Extension Bifurcation Region also exhibited dive variability associated with mesoscale eddy features, with turtles making deeper, longer dives while associated with the strongest total kinetic energy. Turtles in the central North Pacific exhibited seasonality in dive behavior that appeared to reflect synchronous latitudinal movements with the North Pacific Subtropical Front and the associated seasonal, large-scale oceanography. Turtles made deeper, longer dives during the first quarter of the year within this region, the reported time and area where the highest loggerhead bycatch occurs by the longline fishery. These results represent the first comprehensive study of dive data for this species in this region. The increased understanding of juvenile loggerhead dive behavior and the influences of oceanography on dive variability should provide further insight into why interactions with longline fisheries occur and suggest methods for reducing the bycatch of this threatened species. 相似文献
847.
Michael T. Abel Burton Suedel Steven M. Presley Thomas R. Rainwater Galen P. Austin Stephen B. Cox Les N. McDaniel Richard Rigdon Timothy Goebel Richard Zartman Blair D. Leftwich Todd A. Anderson Ronald J. Kendall George P. Cobb 《Environmental geochemistry and health》2010,32(5):379-389
Immediately following hurricane Katrina concern was raised over the environmental impact of floodwaters on the city of New Orleans, especially in regard to human health. Several studies were conducted to determine the actual contaminant distribution throughout the city and surrounding wetlands by analyzing soil, sediment, and water for a variety of contaminants including organics, inorganics, and biologics. Preliminary investigations by The Institute of Environmental and Human Health at Texas Tech University concluded that soils and sediments contained pesticides, semi-volatiles, and metals, specifically arsenic, iron, and lead, at concentrations that could pose a significant risk to human health. Additional studies on New Orleans floodwaters revealed similar constituents as well as compounds commonly found in gasoline. More recently, it has been revealed that lead (Pb), arsenic, and vanadium are found intermittently throughout the city at concentrations greater than the human health soil screening levels (HHSSLs) of 400, 22 (non-cancer endpoint) and 390 μg/g, respectively. Of these, Pb appears to present the greatest exposure hazard to humans as a result of its extensive distribution in city soils. In this study, we spatially evaluated Pb concentrations across greater New Orleans surface soils. We established 128 sampling sites throughout New Orleans at approximately half-mile intervals. A soil sample was collected at each site and analyzed for Pb by ICP-AES. Soils from 19 (15%) of the sites had Pb concentrations exceeding the HHSSL threshold of 400 μg/g. It was determined that the highest concentrations of Pb were found in the south and west portions of the city. Pb concentrations found throughout New Orleans in this study were then incorporated into a geographic information system to create a spatial distribution model that can be further used to predict Pb exposure to humans in the city. 相似文献
848.
Nongrum Ridaphun Kharkongor Mattilang Nongthombam Geetmani Singh Rani Jims World Star Rahman Noimur Kharmawlong George Kupar Nongkhlaw Rishanlang 《Environmental Chemistry Letters》2019,17(3):1325-1331
Environmental Chemistry Letters - The demand for a cleaner environment has led chemists to develop greener protocols, notably by using catalysts. Encapsulation of an active substance on a solid... 相似文献
849.
Tools for comprehensive estimate of coastal region marine economy potential and its use for coastal planning 总被引:1,自引:0,他引:1
George Gogoberidze 《Journal of Coastal Conservation》2012,16(3):251-260
For elaboration of strategy and spatial planning of sustainable coastal regions development it??s very important to know a real potential of development of the region. As parameter, which is comprehensively characterized marine economic, political and military power of the coastal region, it is possible to use the marine economy potential with comprehensive estimations of socio-economic, political, environment and military profits (damages) from coastal planning decisions. Some results, including the European and Russian coastal regions are presented. 相似文献
850.
Patrícia C. Lopes James Adelman John C. Wingfield George E. Bentley 《Behavioral ecology and sociobiology》2012,66(10):1421-1428
Sickness behaviors constitute an array of symptoms exhibited by an animal during the course of an infection, including reduced activity, reduced food and water intake, and reduced social interactions. It is hypothesized that these symptoms enable reallocation of finite energy resources to fight infection. In this way, by focusing energy on healing, available resources are being removed from other activities, potentially reducing adaptive opportunities, such as mating. Hence, to achieve increased reproductive success, animals might be able to adjust the expression of sickness behaviors to their environmental circumstances. While abiotic conditions such as temperature and season can modulate sickness behaviors, no studies in passerines have linked modulation of sickness behaviors to social settings. Here, it is demonstrated that social surroundings affect the extent to which animals exhibit symptoms of sickness. After an immune challenge, zebra finches kept in isolation markedly reduced activity, but those kept in a colony setting did not. The same trend is verified when looking at the time they spent resting. Additionally, a proinflammatory cytokine (interleukin-6) was quantified in plasma samples and all animals that had been immune challenged showed increased levels of this marker, showing that the physiological response was similar. Hence, birds in a social context were able to overcome the behavioral, but not physiological, symptoms usually associated with an inflammatory response. These findings suggest a trade-off between allowing the body to respond to an infection and taking advantage of being in a social situation. 相似文献