全文获取类型
收费全文 | 425篇 |
免费 | 45篇 |
国内免费 | 211篇 |
专业分类
安全科学 | 13篇 |
废物处理 | 34篇 |
环保管理 | 19篇 |
综合类 | 353篇 |
基础理论 | 164篇 |
污染及防治 | 71篇 |
评价与监测 | 22篇 |
社会与环境 | 4篇 |
灾害及防治 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 8篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 21篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 27篇 |
2014年 | 33篇 |
2013年 | 52篇 |
2012年 | 45篇 |
2011年 | 46篇 |
2010年 | 29篇 |
2009年 | 34篇 |
2008年 | 34篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 31篇 |
2004年 | 23篇 |
2003年 | 11篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 22篇 |
1999年 | 12篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有681条查询结果,搜索用时 15 毫秒
161.
K.M.S. Sundaram 《Journal of environmental science and health. Part. B》2013,48(2):295-312
Abstract Effects of azadirachtin (isomer A, AZ‐A) and tebufenozide (TF) on freshwater algae were investigated using indoor aquatic microcosms. AZ‐A and TF were dosed at different concentrations to 10‐L microcosms. Chlorophyll and protein contents of the algae, and the concentrations of the insecticides in water and algae were monitored at intervals of time up to 20 d. Chlorophyll and protein contents in algae were inhibited at treatment levels of 3.0 and 4.5 μg AZ‐A/mL, whereas at 1.5 μg/mL, the chemical stimulated the chlorophyll production. The partition of AZ‐A between water and algae was reversible, and the bioconcentration factor (BCF) was low. In contrast, TF dosed at 0.25 to 0.75 μg/mL stimulated algal growth, probably due to its utilization of carbonaceous and nitrogenous intermediates and other breakdown products of TF as nutrients. The BCF was high and the organism functioned as a sink for the chemical. Extension of the laboratory findings to complex outdoor systems are discussed. 相似文献
162.
A.H. El‐Sebae M.E. Abdel‐Ghanv D. Shalloway M.M. Abou Zeid J. Blancato M.A. Saleh 《Journal of environmental science and health. Part. B》2013,48(6):763-777
Abstract Phosphorylation is an indispensable process for energy and signal transduction in biological systems. AlCl3 at 10 nM to 10 uM range activated in‐vitro [γ‐32P)ATP phosphorylation of the brain (tau) T protein in both normal human or E.coli expressed T forms; in the presence of the kinases P34, PKP, and PKC. However, higher concentrations of ALCl3 inhibited the T phosphorylation with P34, PKP, and PKC to a maximum at 1 mM level. AlCl3 at 100 uM to 500 uM range induced non‐enzymatic phosphorylation of T with γ‐ATP, γ‐GTP, and α‐GTP. AlCl3 activated histone phosphorylation by P34 in a similar pattern. The hyperphosphorylation of T by Al3+ was accompanied by molecular shift and mobility retardation in SDS‐PAGE. This may demonstrate the mechanism of the longterm neurological effect of Al3+ in human brain leading to the formation of the neurofibrillary tangles related to Alzeheimer's disease. 相似文献
163.
好氧污泥颗粒化中胞外聚合物(EPS)的动态变化 总被引:1,自引:0,他引:1
在SBR中分别运行普通活性污泥和好氧颗粒污泥工艺,考察普通絮体污泥颗粒化过程中EPS的组分变化和分布情况.结果表明,通过减少沉淀时间可以获得质量高的颗粒污泥,污泥系统中的EPS可划分为紧密结合型、松散结合型和溶解性3种;普通污泥期、颗粒污泥初期和颗粒污泥稳定期的EPS含量均以紧密结合型EPS为主,颗粒污泥中总EPS和溶解性EPS含量均高于普通污泥,且颗粒形成初期溶解性EPS增长明显;颗粒污泥中紧密结合型EPS含量相对稳定,松散结合型EPS在不同污泥中含量很低,一个典型反应周期中蛋白质和多糖的变化趋势普遍是先降低后上升,普通污泥和颗粒污泥EPS中蛋白质含量均高于多糖,颗粒形成初期EPS中蛋白质含量有明显上升;普通絮体污泥中EPS和细菌分布均匀,颗粒污泥的表层聚集大量的细菌、内部主要成分是EPS. 相似文献
164.
165.
This article presents a method to determine the carbon content of biomass, which is formed when degrading biodegradable polymers in an aerobic aqueous test system. Existing methods for determining the carbon content of biomass (e.g., fumigazation, protein assays, dry solids) have several disadvantages when applied for polymer degradation tests. In this work a protein assay based on the Lowry method was used. It was shown that the ratio between protein and carbon content is not constant but depends on the composition of the microbial population, the growth phase, and the substrate supply. This effect was used for the method presented in this article. For determining the carbon content of biomass the absorbance obtained by the Lowry test is correlated directly with the carbon content of biomass in dependence on the duration of the degradation test. The calibration curves are obtained by a mixed population of microorganisms during the course of a degradation test. 相似文献
166.
T. C. Daniel R. C. Wendt P. E. McGuire D. Stoffel 《Journal of the American Water Resources Association》1982,18(1):117-120
ABSTRACT: Loading rates derived from monitoring natural runoff from selected land uses are compared. Land uses selected for evaluation are construction sites, barnyards, and agriculture (dairying). Runoff volumes, sediment, and nutrient fractions were monitored and expressed as areal loadings for comparison purposes. Sediment yield and total phosphorus (total P) loss was directly proportional to runoff (m3/ha). In decreasing order, the loadings for sediment and total P were as follows: construction site > barnyard > general dairying. Runoff from the barnyard area was approximately 10 times higher in soluble phosphorus and ammonium nitrogen than the other land uses under investigation. Areal loss for nitrate nitrogen was highest from the construction site and was attributed to the higher volume of runoff per unit area. Results show that barnyards in a dairying watershed are potentially a major source of sediment and nutrients, especially those dissolved fractions which have the potential for immediate water quality impacts. Relative to general agricultural land, urban construction sites also appear to be a major source of sediment and nutrients. As with barnyard sites, however, the effect of such sites on water quality likely depends on proximity to surface water bodies and other watershed characteristics affecting delivery ratios of contaminants. 相似文献
167.
Malgorzata Kwiecień 《Environmental monitoring and assessment》1997,46(3):191-207
A new, direct method was developed for quantifying inorganic particulate aerosols trapped by the forest canopy, and for determining the resulting input of elements to a forest ecosystem. The method is based on direct measurements of only six parameters. Using this method, it is possible to determine the load of aerosols trapped by the forest canopy and deposited to leaves, as well as the load of aerosols falling to the forest floor by impaction on plants. It is also possible to estimate the aerosol input of soluble and insoluble elements to an ecosystem. With this new method it has been found that the load of aerosols trapped by the canopy of a mixed forest located in the Rybnik Coal Basin averaged 189.0 kg x ha-1 x growing season-1, or 39.3% of the total inorganic particles reaching the ecosystem. The trapped aerosols provided 13.4 kg x ha-1 of soluble nitrogen and 0.91 kg x ha-1 of insoluble nitrogen over the growing season. At the same time, the input of soluble nitrogen from the atmosphere with rainfall to an open area averaged 13.9 kg x ha-1, and the input of insoluble nitrogen with inorganic dusts averaged 1.4 kg x ha-1. 相似文献
168.
V. Gopal S. Parvathy P. R. Balasubramanian 《Environmental monitoring and assessment》1997,48(2):117-124
Cyprinus carpio were exposed to two non-essential (Hg and Pb)and two essential (Cu and Ni) heavy metal salts at lethal andsub-lethal concentrations. Blood serum total protein, serum globulinand serum albumin was analysed every 2 hr for 24 hrs andagain at 48 and 72 hrs. Serum protein and globulin level showedan intial sharp increase from 2 to 20 hrs, followed by decline thatextend over a period of 72 hrs. Serum albumin showed an initialimmediate decline from 2 to 4 hrs, followed by an intermittent period of recovery and decline that extend over a period of 72hrs. Both lethal and sub-lethal concentrations of metal salts elicited asimilar pattern of response varying only in magnitude. The use offish blood serum protein, albumin and globulin measurements as general indicators of pollutant stress response isdiscussed. 相似文献
169.
Processing and Physical Properties of Plastics Made from Soy Protein Polyester Blends 总被引:6,自引:0,他引:6
Blending soy protein with polyesters using a polyvinyllactam as a compatibilizer successfully made soy protein-based plastics. The polyesters used to produce blends included polycaprolactone (PCL) and Biomax (a commercial biodegradable polyester). The blends were processed by compounding extrusion and injection molding. Blends containing soy protein/Biomax-poly(vinyl alcohol) had tensile strengths ranging from 16–22 MPa, with samples containing larger percentages of the synthetic polymer exhibiting greater strengths. Blends made from soy protein, Biomax, and PCL had tensile strengths ranging from 27–33 MPa. All the blends had high Young's moduli but demonstrated brittle characteristics as evident from their low elongations at break, ranging from 1.8–3.1%. Plastics made from soy protein/polyester blends exhibited low water absorption and had good stability under ambient conditions relative to the plastics made from soy protein alone. Blends made from soy protein flour produced plastics with the lowest water absorption. 相似文献
170.
Soybean protein has been considered as a potential biodegradable polymer in the manufacture of plastics. The purpose of this investigation was to characterize the effect of storage time on thermal and mechanical properties of soybean protein isolate (SPI) plastics. SPI was separated from defatted soy flour, modified with 1M or 2M urea, or plasticized with glycerol, and compression molded into plastics. Plastic made from SPI alone was used as a control. For all SPI plastics, glass transition temperatures and dynamic storage modulus increased and loss tangent decreased during storage. Excess enthalpy of relaxation of all SPI plastics had an exponential relationship with storage time, indicating a fast aging rate at the beginning of storage. All SPI plastics tended to be stiff and brittle during storage. The plastics with glycerol had the slowest aging rate and were fairly stable after 60 days, with about 8.8 MPa tensile strength and 168% strain at break. Plastics with the 2M urea-modification SPI also had a slow aging rate and became relative stable after 60 days, with about 10 MPa tensile strength and 72% elongation. 相似文献