全文获取类型
收费全文 | 9867篇 |
免费 | 113篇 |
国内免费 | 93篇 |
专业分类
安全科学 | 284篇 |
废物处理 | 459篇 |
环保管理 | 1245篇 |
综合类 | 1207篇 |
基础理论 | 2673篇 |
环境理论 | 2篇 |
污染及防治 | 2777篇 |
评价与监测 | 708篇 |
社会与环境 | 669篇 |
灾害及防治 | 49篇 |
出版年
2022年 | 100篇 |
2021年 | 76篇 |
2020年 | 66篇 |
2019年 | 72篇 |
2018年 | 145篇 |
2017年 | 139篇 |
2016年 | 230篇 |
2015年 | 164篇 |
2014年 | 241篇 |
2013年 | 745篇 |
2012年 | 298篇 |
2011年 | 440篇 |
2010年 | 364篇 |
2009年 | 395篇 |
2008年 | 470篇 |
2007年 | 476篇 |
2006年 | 425篇 |
2005年 | 366篇 |
2004年 | 324篇 |
2003年 | 376篇 |
2002年 | 325篇 |
2001年 | 503篇 |
2000年 | 333篇 |
1999年 | 192篇 |
1998年 | 137篇 |
1997年 | 133篇 |
1996年 | 138篇 |
1995年 | 163篇 |
1994年 | 126篇 |
1993年 | 102篇 |
1992年 | 124篇 |
1991年 | 120篇 |
1990年 | 131篇 |
1989年 | 130篇 |
1988年 | 94篇 |
1987年 | 87篇 |
1986年 | 65篇 |
1985年 | 90篇 |
1984年 | 90篇 |
1983年 | 86篇 |
1982年 | 83篇 |
1981年 | 74篇 |
1980年 | 62篇 |
1979年 | 68篇 |
1977年 | 53篇 |
1976年 | 48篇 |
1975年 | 53篇 |
1974年 | 51篇 |
1973年 | 53篇 |
1970年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
771.
Two fundamental aspects of invasion dynamics are population growth and population spread. These quantities have been subject of study in biological invasions and can be used to study management and control of organisms. In this paper we derive formulae to calculate wave speed and rates of spread for coupled map lattices. Coupled map lattice models are dynamical models where space and time are discrete. We also show how wave speed and rate of spread can be calculated for structured population coupled map lattices in deterministic, stochastic environments and heterogeneous landscapes. Coupled map lattices are simple mathematical models that can be easily linked to landscape data to study invading organisms control strategies. 相似文献
772.
Many species of sedentary marine invertebrates exhibit large spatial variation in their morphology, which allow them to occupy
a broad geographic distribution and range of environmental conditions. However, the detection of differences in morphology
amongst variable environments cannot determine whether these differences represent a plastic response to the local environment,
or whether morphology is genetically fixed. We used a reciprocal transplant experiment to test whether ‘stunted’ blacklip
abalone (Haliotis rubra) are the result of a plastic response to the environment or fixed genetic trait. Furthermore, we related environmental factors,
that affect food availability (density of abalone, water movement, algal cover and reef topography), to differences in growth
and morphology. Morphological plasticity was confirmed as the mechanism causing morphological variation in H. rubra. Individuals transplanted to sites with ‘non-stunted’ H. rubra grew significantly faster when compared to stunted controls, whilst individuals transplanted to stunted sites grew significantly
slower compared to non-stunted controls. The growth response was greater for individuals transplanted from ‘non-stunted’ to
‘stunted’ sites, suggesting that the environmental stressors in morphologically ‘stunted’ habitat are stronger compared to
locations of faster growing morphology. We propose that these differences are related to resource availability whereby low
algal cover and topographic simplicity results in stunted populations, whereas high algal abundance and topographic complexity
results in non-stunted populations. 相似文献
773.
774.
Polypropylene (PP) meltblown fibers were coated with titanium dioxide (TiO2) nanoparticles using layer-by-layer (LbL) deposition technique. The fibers were first modified with 3 layers of poly(4-styrenesulfonic acid) (PSS) and poly(diallyl-dimethylammonium chloride) (PDADMAC) to improve the anchoring of the TiO2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic TiO2 nanoparticles to construct TiO2/PDADMAC bilayer in the LbL fashion. The number of deposited TiO2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust TiO2 loading. The LbL technique showed higher TiO2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue (MB). Results showed that the TiO2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of TiO2 powder dispersed in solution. The deposition of TiO2 3 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr. TiO2-LbL constructions also preserved TiO2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of TiO2 particles from the substrate outer surface. However, even in the third cycle, the TiO2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment. 相似文献
775.
Shuyan Wang Lin Du Narcisse T.Tsona Xiaotong Jiang Bo You Li Xu Zhaomin Yang Wenxing Wang 《环境科学学报(英文版)》2020,32(6):151-162
Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3) K,atmospheric pressure,(18±2)% relative humidity,and under different NOx and SO2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS) and the results showed that the ad... 相似文献
776.
777.
Compounds in the atmosphere contaminate samples of groundwater. An inexpensive and simple method for collecting groundwater samples is developed to prevent contamination when the background concentration of contaminants is high. This new design of groundwater sampling device involves a glass sampling bottle with a Teflon-lined valve at each end. A cleaned and dried sampling bottle was connected to a low flow-rate peristaltic pump with Teflon tubing and was filled with water. No headspace volume was remained in the sampling bottle. The sample bottle was then packed in a PVC bag to prevent the target component from infiltrating into the water sample through the valves. In this study, groundwater was sampled at six wells using both the conventional method and the improved method. The analysis of trichlorofluoromethane( CFC-11 ) concentrations at these six wells indicates that all the groundwater samples obtained by the conventional sampling method were contaminated by CFC-11 from the atmosphere. The improved sampling method greatly eliminated the problems of contamination, preservation and quantitative analysis of natural water. 相似文献
778.
779.
T. Tønnesen A.-M. Gerdes E. Damsgaard P. Miny W. Holzgreve F. Søndergaard N. Horn 《黑龙江环境通报》1989,9(3):159-165
Chorionic villus samples with copper contents of 1·91, 4·2, 5·6, and 6·3 ng/mg were observed in four cases with male karyotypes. These values were outside the range for unaffected males (0·30–0·85 ng/mg), and three of them were outside the control range (0·20–2·39 ng/mg). But these three values were below the values previously observed for affected Menkes fetuses (12·0–24·8 ng/mg). Follow-up by 64Cu uptake studies on the amniotic fluid cells was performed in three of these cases. A combination of 64Cu uptake and chase experiments on the amniotic fluid cells showed more convincingly than 64Cu uptake per se the direct copper values of 4·2 and 5·6 ng/mg to correspond to affected fetuses. Amniotic fluid cells from the male fetus with the CV copper value of 1·9 ng/mg showed normal results. The CV copper value of 6·3 ng/mg was considered pathognomonic for Menkes disease. The pregnancy was terminated, and the diagnosis was confirmed on fetal fibroblasts. Maternal deciduum prepared from the placentae showed in one of the cases with an affected fetus copper values ranging from 1·5 to 5·7 ng/mg. In six additional diagnostic cases, the copper content was determined in both CV samples and maternal deciduum. In three of these cases with normal CV sample copper, maternal decidua values of 4·85–7·8 ng/mg copper were observed. These results show that maternal deciduum contamination of a CV sample could cause a false-positive diagnosis. 相似文献
780.