全文获取类型
收费全文 | 3575篇 |
免费 | 366篇 |
国内免费 | 1290篇 |
专业分类
安全科学 | 539篇 |
废物处理 | 95篇 |
环保管理 | 392篇 |
综合类 | 2371篇 |
基础理论 | 819篇 |
环境理论 | 1篇 |
污染及防治 | 527篇 |
评价与监测 | 111篇 |
社会与环境 | 296篇 |
灾害及防治 | 80篇 |
出版年
2024年 | 5篇 |
2023年 | 46篇 |
2022年 | 98篇 |
2021年 | 136篇 |
2020年 | 131篇 |
2019年 | 145篇 |
2018年 | 145篇 |
2017年 | 183篇 |
2016年 | 203篇 |
2015年 | 217篇 |
2014年 | 223篇 |
2013年 | 371篇 |
2012年 | 359篇 |
2011年 | 405篇 |
2010年 | 284篇 |
2009年 | 243篇 |
2008年 | 223篇 |
2007年 | 312篇 |
2006年 | 247篇 |
2005年 | 181篇 |
2004年 | 157篇 |
2003年 | 144篇 |
2002年 | 114篇 |
2001年 | 89篇 |
2000年 | 78篇 |
1999年 | 76篇 |
1998年 | 63篇 |
1997年 | 55篇 |
1996年 | 44篇 |
1995年 | 56篇 |
1994年 | 43篇 |
1993年 | 37篇 |
1992年 | 16篇 |
1991年 | 23篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有5231条查询结果,搜索用时 218 毫秒
471.
Kirk Hamilton 《Environment, Development and Sustainability》2003,5(3-4):419-436
Genuine saving measures the real change in0 total wealth, factoring in the depreciation of produced assets, depletion of natural resources, pollution damages, and expenditures on education. This paper presents a theoretical framework for measuring changes in wealth in total and per capita terms, establishes the link between savings measures and prospects for social welfare, and provides summary empirical estimates of the savings measures. China excepted, the majority of countries below median income are distinguished by apparent declines in total wealth per capita. 相似文献
472.
A computerized system which simultaneously acquires and quantifies several ultrasonically detected fetal activities, including gross body movements, breathing movements, and eye movements, was developed in order to obtain additional quantitative data on fetal behaviour. Movements were automatically related to fetal heart rate allowing computation of their mean incidence, duration, lag time and percentage time spent moving during different heart rate patterns. The incidence of various behavioural states was also calculated. The study of 15 healthy fetuses near term revealed the existence of statistically significant differences in these parameters between low and high variability patterns of fetal heart rate suggesting a quantitative modulation of fetal movements by behavioural states. 相似文献
473.
The variations of the biochemical composition of Tetraselmis suecica and Isochrysis galbana during growth and decay were determined. the content of chlorophyll a (Chl-a) of the cultures, as expected, slowly degraded into phaeopigments during decay, confirming that chlorophyll measurements do not always provide an accurate estimate of phytoplanktonic biomass and, consequently, may fail if used to measure the food availability of particulate matter for consumers. Measurements of total amounts of proteins, carbohydrates and lipids, related to the nutritional value of particles in terms of caloric content, are shown to provide information on the readily available food for consumers, particularly during the blooms. the protein/carbohydrate, C/N and POC/Chl-a ratios were used to evaluate the differences between these two species during the growth and the decomposition processes. A comparison between experimental and field conditions was undertaken to implement our understanding of the growth and degradation processes of particulate organic matter of phytoplanktonic origin in the sea and its role on natural systems, during and after phytoplankton blooms. 相似文献
474.
475.
Mak KS Griebler C Meckenstock RU Liedl R Peter A 《Journal of contaminant hydrology》2006,88(3-4):306-320
In recent years, compound specific isotope analyses (CSIA) have developed into one of the most powerful tools for the quantification of in situ biodegradation of organic contaminants. In this approach, the calculation of the extent of biodegradation of organic contaminants in aquifers is usually based on the Rayleigh equation, and thus neglects physical transport processes such as dispersion that contribute to contaminant dilution in aquifers. Here we combine compound specific isotope analyses with a conservative transport model to study the attenuation of aromatic hydrocarbons at a former gasworks site. The conservative transport model was first used to simulate concentration reductions caused by dilution at wells downgradient of a BTEX source. In a second step, the diluted concentrations, together with the available stable carbon isotope ratios and carbon fractionation factors for benzene, toluene and o-xylene were applied in the Rayleigh equation to quantify the degree of biodegradation at each of those wells. At the investigated site, where other attenuation processes such as sorption and volatilisation were proven to be negligible, the combined approach is recommended for benzene, which represents a compound for which the effect of biodegradation is comparable to or less than the effect of dilution. As demonstrated for toluene and o-xylene, the application of the Rayleigh equation alone is sufficient if dilution can be proved to be insignificant in comparison to biodegradation. The analysis also suggests that the source width and the position of the observation wells relative to the plume center line are significantly related to the degree of dilution. 相似文献
476.
PCDDs, PCDFs, and coplanar PCBs in wild terrestrial mammals from Japan: congener specific accumulation and hepatic sequestration 总被引:1,自引:0,他引:1
Kunisue T Watanabe MX Iwata H Tsubota T Yamada F Yasuda M Tanabe S 《Environmental pollution (Barking, Essex : 1987)》2006,140(3):525-535
The present study determined the contamination levels and congener-specific accumulation features of dioxins and related compounds (DRCs) in wild terrestrial mammals such as large Japanese field mice (LJFM), lesser Japanese moles (LJMs), and raccoon dogs (RDs) collected from Kanto region in Japan during 2001. The toxic equivalent quantity (TEQ) levels in the carcasses or adipose tissues were in the order of RDs > or = LJMs > LJFM. Comparison of DRC congener profiles in the three species and principal component analysis (PCA) demonstrated a higher contribution of OCDD, T4CB77, and P5CB118 in LJMs. Analysis of liver-adipose distribution of DRC congeners in RDs showed that livers contained significantly higher TEQs than adipose tissues, indicating that liver is a depository organ and critical for determining the toxicokinetics of DRCs. As for most T4, P5, H6CDD/DFs and for P5CB126, H6CB169 and mono-ortho PCB congeners, their liver/adipose concentration ratios in RDs revealed a tendency to increase with hepatic TEQ levels, suggesting TEQ-dependent hepatic sequestration. 相似文献
477.
中国经济增长对碳排放的影响分析 总被引:44,自引:1,他引:43
通过相关分析探讨了中国国内生产总值(GDP)的增长与碳排放量的关系.结果表明,二者有明显的相关性(R2=0.958 1).进一步研究认为,由于中国投资率在35%~40%以上,且工业增加值占GDP的比重超过50%,因此中国过分依赖投资的经济增长方式和以第二产业(工业)为主的经济结构在很大程度上是导致温室气体排放量增加的主要原因.未来在全球化背景下,经济增长可转变为更多地依靠科技创新、技术进步和制度的改进,因此,调整经济增长方式和产业结构,可以在保持发展经济的同时,使碳排放强度呈逐渐下降的趋势. 相似文献
478.
E. Vartiainen M. Kulmala T.M. Ruuskanen R. Taipale J. Rinne H. Vehkamki 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):7882-7892
Oxidation of d-limonene, which is a common monoterpene, can lead to new aerosol particle formation in indoor environments. Thus, products containing d-limonene, such as citrus fruits, air refresheners, household cleaning agents, and waxes, can act as indoor air aerosol particle sources. We released d-limonene into the room air by peeling oranges and measured the concentration of aerosol particles of three different size ranges. In addition, we measured the concentration of d-limonene, the oxidant, and the concentration of ozone, the oxidizing gas. Based on the measurements we calculated the growth rate of the small aerosol particles, which were 3–10 nm in diameter, to be about , and the losses of the aerosol particles that were due to the coagulation and condensation processes. From these, we further approximated the concentration of the condensable vapour and its source rate and then calculated the formation rate of the small aerosol particles. For the final result, we calculated the nucleation rate and the maximum number of molecules in a critical cluster. The nucleation rate was in the order of and the number of molecules in a critical-sized cluster became 1.2. The results were in agreement with the activation theory. 相似文献
479.
Leakage diagnosis of hydrocarbon pipelines can prevent environmental and financial losses. This work proposes a novel method that not only detects the occurrence of a leakage fault, but also suggests its location and severity. The OLGA software is employed to provide the pipeline inlet pressure and outlet flow rates as the training data for the Fault Detection and Isolation (FDI) system. The FDI system is comprised of a Multi-Layer Perceptron Neural Network (MLPNN) classifier with various feature extraction methods including the statistical techniques, wavelet transform, and a fusion of both methods. Once different leakage scenarios are considered and the preprocessing methods are done, the proposed FDI system is applied to a 20-km pipeline in southern Iran (Goldkari-Binak pipeline) and a promising severity and location detectability (a correct classification rate of 92%) and a low False Alarm Rate (FAR) were achieved. 相似文献
480.
曹靓 《城市环境与城市生态》2004,17(2):33-34
物化法是处理混合电镀废水的一种有效方法,对COD、Pb离子、Ni离子尤其是Pb离子、Ni离子的处理效果非常理想。COD的去除率达到80.1%,Pb离子的去除率达到97.2%,Ni离子的去除率达到98.1%,中间产出的污泥也可得到较好处理。 相似文献