全文获取类型
收费全文 | 17579篇 |
免费 | 4899篇 |
国内免费 | 27725篇 |
专业分类
安全科学 | 1724篇 |
废物处理 | 655篇 |
环保管理 | 1490篇 |
综合类 | 32950篇 |
基础理论 | 3423篇 |
环境理论 | 1篇 |
污染及防治 | 6881篇 |
评价与监测 | 1832篇 |
社会与环境 | 711篇 |
灾害及防治 | 536篇 |
出版年
2024年 | 45篇 |
2023年 | 223篇 |
2022年 | 560篇 |
2021年 | 535篇 |
2020年 | 1093篇 |
2019年 | 2155篇 |
2018年 | 2332篇 |
2017年 | 2389篇 |
2016年 | 2124篇 |
2015年 | 2573篇 |
2014年 | 3319篇 |
2013年 | 3599篇 |
2012年 | 3434篇 |
2011年 | 2976篇 |
2010年 | 2713篇 |
2009年 | 2687篇 |
2008年 | 2369篇 |
2007年 | 2265篇 |
2006年 | 1776篇 |
2005年 | 1326篇 |
2004年 | 1143篇 |
2003年 | 964篇 |
2002年 | 795篇 |
2001年 | 805篇 |
2000年 | 921篇 |
1999年 | 745篇 |
1998年 | 581篇 |
1997年 | 523篇 |
1996年 | 548篇 |
1995年 | 473篇 |
1994年 | 322篇 |
1993年 | 255篇 |
1992年 | 321篇 |
1991年 | 279篇 |
1990年 | 244篇 |
1989年 | 204篇 |
1988年 | 151篇 |
1987年 | 70篇 |
1986年 | 78篇 |
1985年 | 54篇 |
1984年 | 59篇 |
1983年 | 44篇 |
1982年 | 52篇 |
1981年 | 35篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1971年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
The research, focused on the specific interactions among seven plant secondary compounds and aphids, was carried out and the preliminary results showed: (1) "T-typed tube method" was regarded as the best method compared with others designed to observe the interactions. (2) Cabbage aphid was able to be attracted by laurolene while it was not susceptible to α-pinene, β-pinene and diamylene. (3) Gossypol, a major secondary substance in cotton, was able to be implicated as feeding attractant to cotton aphid. (4) Rutin might be implicated repellent to cotton aphid. 相似文献
132.
分析了毛细饱水带的水动力学特性,指出在地下水污染研究中,污染物在毛细饱和水带和潜水怪具有相同的水平运动规律,并以实例分析说明该带对污染物运移的重要性。建议在研究和一非饱和条件地下水及污染物运动问题时把毛细饱水带与潜水含水层统一为饱马毛细饱水带顶面作为饱水面。 相似文献
133.
Chris J. Matthews David B. Newton Roger D. Braddock Bofu Yu 《Environmental Modeling and Assessment》2007,12(1):27-41
Recently, the New Morris Method has been presented as an effective sensitivity analysis tool for mathematical models. The
New Morris Method estimates the sensitivity of an output parameter to a given set of input parameters (first-order effects)
and the extent these parameters interact with each other (second-order effects). This method requires the specification of
two parameters (runs and resolution) that control the sampling of the output parameter to determine its sensitivity to various
inputs. The criteria for these parameters have been set on the analysis of a well-behaved analytical function (see Cropp and
Braddock, Reliab. Eng. Syst. Saf. 78:77–83, 2002), which may not be applicable to other physical models that describe complex
processes. This paper will investigate the appropriateness of the criteria from (Cropp and Braddock, 2002) and hence the effectiveness
of the New Morris Method to determine the sensitivity behaviour of two hydrologic models: the Soil Erosion and Deposition
System and Griffith University Representation of Urban Hydrology. In the first case, this paper will separately analyse the
sensitivity of an output parameter on a set of input parameters (first- and second-order effects) for each model and discuss
the physical meaning of these sensitivities. This will be followed by an investigation into the sampling criteria by exploring
the convergence of the sensitivity behaviour for each model as the sampling of the parameter space is increased. By comparing
these trends to the convergence behaviour from Cropp and Braddock (2002), we will determine how well the New Morris Method
estimates the sensitivity for each model and whether the sampling criteria are appropriate for these models. It will be shown
that the New Morris Method can provide additional insight into the functioning of these models, and that, under a different
metric, the sensitivity behaviour of these models does converge confirming the sampling criteria set by Cropp and Braddock. 相似文献
134.
连续采样与五日法采样效果及费用的对比分析 总被引:2,自引:0,他引:2
通过对连续采样与五日法采样五种方法监测结果及所需费用的比较,得出连续采样方法监测结果更具有代表性,合理性,一次性投资大,但运行费用并不高的结论。 相似文献
135.
Yu. A. Anokhin 《Environmental monitoring and assessment》1988,11(3):315-325
The global cycles of man-produced pollutants entering the natural environment are reflected in changes of pollutant cycles, even in background regions.The system of mathematical balance simulation models of inorganic pollutant distribution and circulation (some heavy metals and pesticides included in the priority list for integrated background monitoring) has been developed for the Lake Baikal drainage basin. The system consists of the following units: (1) inventory and classification of regional sources of pollutants entering the atmosphere, natural waters and soils; (2) computation of the global atmospheric transfer and depositions; (3) regional spreading with atmospheric fluxes and deposition onto the underlying surfaces; (4) transport with waterflows feeding Lake Baikal; (5) transport with the lake currents and balance in the lake.The models developed have enabled improvement of existing programmes and systems of observations, in particular to substantiate the large-scale snow sampling and analysis network, and to develop the programme of integrated surveys of the state of Lake Baikal. Since 1981 these actions have been included in the operational network observations within the Lake Baikal Monitoring System. 相似文献
136.
Faculty position announcement 相似文献
137.
A membrane extraction-gas chromatography method was developed fordetermination of organophosphorus pesticides and related compounds including methamidophos, DDVP, dimethoate, methyl parathion, parathion, thiophosphoric acid trimethyl ester, and thiophosphoramidic acid dimethyl ester in water samples. In thismethod, surface-modified acetic cellulose membranes were used to extract the target analytes in water samples, the extracted analytes were back-extracted into a small amount of methanol, andgas chromatography with pulsed flame photometric detector (GC-PFPD) was used to determine the concentrations of targetanalytes in the extracts. The recoveries obtained for thetarget analytes spiked into the water samples ranged from 66to 94%. The method detection limit for each target analyte was 0.05 g L-1. The method developed in this study had shown the advantages of being cheap, simple, fast, and reliable. It had been used successfully to determine the concentrations of target analytes in river water samples. 相似文献
138.
Yu.M. Svirezhev W. von Bloh H.-J. Schellnhuber 《Environmental Modeling and Assessment》1999,4(4):287-294
A novel approach to the problem of estimating climate impact on social systems is suggested. This approach is based on a risk concept, where the notion of critical events is introduced and the probability of such events is estimated. The estimation considers both the inherent stochasticity of climatic processes and the artificial stochasticity of climate predictions due to scientific uncertainties. The method is worked out in some detail for the regional problem of crop production and the risks associated with global climate change, and illustrated by a case study (Kursk region of the FSU). In order to get local climatic characteristics (weather), a so-called statistical weather generator is used. One interesting finding is that the 3% risk level remains constant up to 1.0–1.1°C rise of mean seasonal temperature, if the variance does not change. On the other hand, the risk grows rapidly with increasing variance (even if the mean temperature rises very slowly). The risk approach is able to separate two problems: (i) assessment of global change impact, and (ii) decision making. The main task for the scientific community is to provide the politicians with different options; the choice of admissible (from the social point of view) critical events and the corresponding risk levels is the business of decision makers. 相似文献
139.
通过实验与实际工程相结合,定量描述了大气采样系统中金属氧化物的存在对SO2测定值的影响,并阐述了其反应机理,提出了相应措施。 相似文献
140.
用密切值法评价沙湾荒漠区生态环境质量 总被引:3,自引:0,他引:3
利用多目标决策中的密切值法进行沙湾荒漠区生态环境综合评价。该方法简便、适用、且分辨率较高,对各监测点群的定量描述符合实际状况。 相似文献