首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   548篇
  免费   62篇
  国内免费   402篇
安全科学   20篇
废物处理   8篇
环保管理   36篇
综合类   523篇
基础理论   322篇
污染及防治   49篇
评价与监测   8篇
社会与环境   28篇
灾害及防治   18篇
  2024年   4篇
  2023年   15篇
  2022年   29篇
  2021年   49篇
  2020年   32篇
  2019年   28篇
  2018年   37篇
  2017年   49篇
  2016年   38篇
  2015年   50篇
  2014年   46篇
  2013年   73篇
  2012年   54篇
  2011年   50篇
  2010年   39篇
  2009年   46篇
  2008年   25篇
  2007年   40篇
  2006年   39篇
  2005年   39篇
  2004年   25篇
  2003年   25篇
  2002年   24篇
  2001年   19篇
  2000年   24篇
  1999年   17篇
  1998年   11篇
  1997年   12篇
  1996年   11篇
  1995年   10篇
  1994年   10篇
  1993年   20篇
  1992年   8篇
  1991年   3篇
  1990年   5篇
  1989年   3篇
  1988年   2篇
  1987年   1篇
排序方式: 共有1012条查询结果,搜索用时 15 毫秒
101.
镧对酸雨胁迫下水稻种子可溶性蛋白和脯氨酸含量的影响   总被引:1,自引:0,他引:1  
分别采用pH值为2.0,2.5,3.0,3.5,4.0,4.5和5.0的模拟酸雨和La(浓度为1mg·l-1)处理水稻种子,测定不同酸雨胁迫下La对水稻种子可溶性蛋白和脯氨酸含量的影响,结果表明,当酸雨胁迫7d时,随胁迫强度的增加(pH5.0-2.0),可溶性蛋白含量逐渐降低,而脯氨酸含量逐渐升高.La可缓解pH5.0-3.0胁迫的伤害;但对pH2.5-2.0无明显防御作用.pH4.0时,解除酸雨胁迫(t=5d,3d)后可溶性蛋白含量即时提升(第6天和第4天),La处理亦可提高可溶性蛋白含量,对脯氨酸含量均无明显影响,pH2.5处理过长时(t≥5d),对水稻种子造成不可逆伤害,可溶性蛋白含量小于对照,而脯氨酸含量大于对照,La处理无明显效应;当酸雨处理3d时,可溶性蛋白与脯氨酸含量均显著大于对照,经La处理后均有所提高,表明La丑对酸雨胁迫下水稻种子萌发有一定防御作用.  相似文献   
102.
不同有机物料对水稻根表铁膜及砷镉吸收转运的影响   总被引:1,自引:0,他引:1  
李开叶  赵婷婷  陈佳  赵秀兰 《环境科学》2021,42(4):2047-2055
通过盆栽试验研究了油菜秸秆、蚕豆秸秆、泥炭、猪粪堆肥和生物炭这5种有机物料对贵州石灰岩黄壤区某砷(As)和镉(Cd)复合污染稻田土壤As/Cd有效性、水稻根表铁膜及As/Cd吸收转运的影响.结果表明,施用有机物料显著提高了有机质和水稻生物量;除油菜秸秆对土壤pH值影响不明显外,施用有机物料显著提高土壤pH值,使土壤有效Cd含量降低34.77%~82.69%;猪粪堆肥和生物炭使土壤有效As含量显著提高,油菜秸秆和泥炭处理使土壤有效As含量显著降低;施用有机物料有助于水稻根表铁膜的形成,并使其中Cd、As含量分别提高17.73%~151.03%和28.49%~94.86%,使水稻糙米Cd含量降低15.87%~79.45%,As含量降低27.04%~82.51%,降幅以生物炭处理最大;有机物料还显著降低Cd在根-茎-叶-籽粒的转运系数及As从茎向籽粒转运系数.相关分析表明,土壤pH、有效Cd和铁膜Cd含量是影响籽粒Cd累积的主要因素,土壤pH、有机质和铁膜As含量是影响籽粒As累积的主要因素.有机物料通过改变土壤pH、有机质含量及铁膜中As和Cd含量,影响水稻对As和Cd的吸收和转运.  相似文献   
103.
以稻秆为固体碳源处理分散养猪冲洗水的试验研究   总被引:1,自引:0,他引:1  
针对分散养猪废水经厌氧和人工湿地处理后存在C/N低的问题,以廉价的稻秆作为固体碳源和生物膜载体,研究反应器启动阶段运行性能、水力负荷的影响以及污染物沿程去除特性.结果表明NO3--N主要在反应器上部稻秆填充层被去除,去除率超过95%,且无明显NO2--N积累,反硝化速率为0.052mg/(g·h).稻秆本身会浸出释放有机物和氮(主要为NH4+-N),导致运行前期出水COD和NH4+-N高于进水,但仍远低于《畜禽养殖业污染物排放标准》(GB18596-2001)的排放限值,40d后COD逐步降至40mg/L左右.COD和NO3--N可在反应器下部的砖渣填充层被进一步去除.  相似文献   
104.
The current study investigated the effects of nano-silicon (Si) and common Si on lead (Pb) toxicity, uptake, translocation, and accumulation in the rice cultivars Yangdao 6 and Yu 44 grown in soil containing two different Pb levels (500 mg·kg−1 and 1000 mg·kg−1). The results showed that Si application alleviated the toxic effects of Pb on rice growth. Under soil Pb treatments of 500 and 1000 mg·kg−1, the biomasses of plants supplied with common Si and nano-Si were 1.8%–5.2% and 3.3%–11.8% higher, respectively, than those of plants with no Si supply (control). Compared to the control, Pb concentrations in rice shoots supplied with common Si and nano-Si were reduced by 14.3%–31.4% and 27.6%–54.0%, respectively. Pb concentrations in rice grains treated with common Si and nano-Si decreased by 21.3%–40.9% and 38.6%–64.8%, respectively. Pb translocation factors (TFs) from roots to shoots decreased by 15.0%–29.3% and 25.6%–50.8%, respectively. The TFs from shoots to grains reduced by 8.3%–13.7% and 15.3%–21.1%, respectively, after Si application. The magnitudes of the effects observed on plants decreased in the following order: nano-Si treatment>common Si treatment and high-grain-Pb-accumulating cultivar (Yangdao 6)>low-grain-Pb-accumulating cultivar (Yu 44) and heavy Pb stress (1000 mg·kg−1)>moderate Pb stress (500 mg·kg−1)>no Pb treatment. The results of the study indicate that nano-Si is more efficient than common Si in ameliorating the toxic effects of Pb on rice growth, preventing Pb transfer from rice roots to aboveground parts, and blocking Pb accumulation in rice grains, especially in high-Pb-accumulating rice cultivars and in heavily Pb-polluted soils.  相似文献   
105.
Cd胁迫下杂交水稻对Cd的吸收及其动态变化   总被引:2,自引:0,他引:2  
镉(Cd)是非必需的有毒元素,是农业环境和农产品的重要污染物,易被水稻吸收并在籽粒中积累。不同水稻品种拥有不同的独特基因,导致水稻籽粒吸收积累Cd的能力存在一定的差异。因此,开展不同水稻品种耐Cd特性及其不同生育期的吸收转运效率研究具有重要意义。本文采用水培试验,研究了两个水稻(Oryza sativa L.)品种:D83A/R527(低吸收累积Cd)和辐优838(高吸收累积Cd)在不同质量浓度Cd胁迫下籽粒Cd质量分数及不同生育时期水稻根、茎、叶内Cd的吸收积累量及其动态变化特点。结果表明,两种水稻品种在Cd胁迫下籽粒Cd积累量差异显著,辐优838在1.0 mg·L^-1 Cd质量浓度胁迫下籽粒Cd质量分数就已超过国家食品卫生标准;在1.0~3.0 mg·L^-1 Cd质量浓度胁迫下,D83A/R527籽粒内Cd质量分数仅为辐优838的50~60%。随着Cd处理浓度增加和生育时期推进,两种水稻各部位Cd吸收量均表现为逐渐增加,其增加幅度总体表现为:辐优838〉D83A/R527;不同部位中,根的积累效应最强,叶片吸收积累能力最低,辐优838茎、叶吸收积累效率分别是D83A/R527的1.5~2.0倍左右。在1.0~3.0mg·L^-1 Cd胁迫下,水稻Cd积累差异较为显著的时期为灌浆期,辐优838的根系向茎、叶的转移效率大于D83A/R527,且D83A/R527主要表现为由根系向茎Cd转移效率较高,叶片Cd积累相对较少。灌浆期是水稻籽粒干物质积累的重要时期,也是吸收累积Cd的重要时期,这为筛选低吸收积累水稻品种和调控Cd在水稻籽粒中的吸收累积奠定了重要理论基础。  相似文献   
106.
Smoke and salinity are environmental hazards. Smoke produced DNA damage, inflammatory, and oxidative stress in humans while salinity reduced plant yield. However, smoke from plants is beneficial towards plant growth. In this study, smoke of two plants, Buhania varegata (1:1000 and 1:5000 dilutions (v/v)) and Cymbopogon jwarancusa (1:500 and 1:1000), were used to determine effects on different physiological and biochemical parameters in rice Basmati-385 (B-385) and Shaheen Basmati under different saline concentrations (control: 50, 100, and 150 mM). With increasing salinity, germination%, seedling growth, K+, Ca+, cell membrane stability, and total nitrogen and protein contents were decreased while Na+ content increased. However, seeds primed with different dilution of smoke significantly diminished the adverse effects of salinity and shown to produce positive responses in all of the above parameters. The most effective dilutions were 1:5000 for Buhania varegata and C-500 for Cymbopogon jwarancusa. It seems that priming with plant smoke solution is a potent stimulant for plant growth exerting a significant role in physiology and biochemistry of rice plants under saline condition.  相似文献   
107.
A study was performed in a Protected Area (Natural Reserve of Sado Estuary) in 1996, to evaluate the acute toxicity for aquatic life of surface water from rice fields treated with pesticides, particularly with molinate and quinclorac. As a preliminary assessment, the following rapid toxicity tests were used: “Rotoxkit F”;, “Thamnotoxkit F”; and the recently introduced “Daphtoxkit F magna”; and “Algaltoxkit F”;. Water samples were collected from: a water source for irrigating the rice fields, two rice plots, a drainage channel and from Sado river in which the water is discharged. The results showed that samples from the rice plot treated with molinate were more toxic than those obtained from rice plot treated with quinclorac. Water samples from the river were the most toxic, causing 100% of immobility in all organisms and a substantial inhibition in the algal growth. Water collected from the drainage channel in late July, was also found to be quite toxic. The results obtained until now indicate that some characteristics of these microbiotests, like their rapidity, simplicity and relatively low cost, make them a practical tool to evaluate acute effects of pesticides in freshwater ecosystems. They may also contribute to suggest some changes in pesticides use to promote agricultural practices with lower impact to aquatic life.  相似文献   
108.
刘刚  李久海  徐慧  吴丹 《中国环境科学》2013,33(12):2140-2147
在明火燃烧和闷烧条件下对6种稻草和5种玉米秸秆进行了燃烧试验,并对烟尘中的正构烯烃进行了分析.结果表明,在稻草明火烟尘中,正构烯烃由C15~C29组成,其平均总含量为918.7mg/kg,低碳数与高碳数正构烯烃含量比(L/H)的平均值为0.6,碳优势指数(CPI)的平均值为1.2.正构烯烃呈双峰式分布,两个峰碳数主要是C24和C28.在稻草闷烧烟尘中,正构烯烃由C17~C29组成,其总含量、L/H、CPI等的平均值分别是517.0mg/kg、0.7和0.9.正构烯烃同样呈双峰型分布,两个峰碳数主要是C23和C28.在玉米秸秆的明火烟尘中,正构烯烃由C19~C29组成.其总含量、L/H、CPI等的平均值分别为126.0mg/kg、0.7和1.3.正构烯烃呈单峰型分布,主峰碳数主要是C24和C23.在玉米秸秆的闷烧烟尘中,正构烯烃由C17~C29组成,其总含量、L/H、CPI等的平均值分别是198.9mg/kg、1.8和 0.9.正构烯烃呈双峰式分布,其主峰碳数均为C23,次峰碳数主要是C29.在两类秸秆燃烧产生的烟尘之间,正构烯烃的组成存在明显差别.这有助于识别气溶胶中稻草或玉米秆燃烧来源的此类污染物.  相似文献   
109.
Addition of plant residue into soils improves soil physiochemical properties and its fertility. Rapeseed residue is an emerging N source to paddy soils via rice-rape double-cropping practice. The objective of this study was to evaluate the effects of rapeseed residue and eggshell waste on chemical changes and enzyme activity in the rice paddy soil. The powdered eggshells at 0, 1, 3, and 5% were applied once to 7.0 kg paddy repacked soils in each pot treated with the rapeseed residue or the conventional N, P, and K fertilisers. Eight rice seedlings (Oriza sativa L. cv. Ilmibyeo) (40 days after sowing) were transplanted to the treated each pot. The contents of total C (TC) and N (TN), and organic matter (OM) were significantly increased in soils treated with the rapeseed residue compared to the N, P, and K fertilisers. With the addition of eggshell containing ~92% CaCO3, a considerable increase of soil pH was observed in soils treated with the rapeseed residue and the N, P, and K fertilisers, compared to the untreated soil. Activities of β-glucosidase, urease, and arylsulfatase enzymes were higher in soils treated with the rapeseed residue than soils treated with the N, P, and K fertilisers. The eggshell additions at 1, 3, and 5% into soils treated with the rapeseed residue increased enzyme activity mainly resulting from N mineralisation, whereas no change in enzyme activity was observed in the soils treated with the NPK fertiliser. The combined use of the rapeseed residue and the eggshells can be beneficial to improve soil environment.  相似文献   
110.
Thirty landraces of rice collected from various locations, across an elevational gradient (1150–2400 m asl), in Kumaun, Central Himalaya and VL-206 (a high-yielding variety recommended for rainfed mountain area) have been evaluated, both in terms of quantity and nutritional quality of straw. Data were collected to estimate the percentage share of fodder in the overall biomass produced. The total biomass harvested at maturity was taken as productivity. In view of the severe scarcity of fodder in hill regions, particularly during winter months, straw was also examined for quality-linked biochemical parameters and dry matter digestibility (DMD) of fodder. The Crude Protein (CP) values ranged from 2.21% (Nandhani) to 6.33% (Dalbadal), and in saceo DMD (nylonbag technique) was highest in Kaladur (48.84%) and lowest in Kantolia (32.25%). While the CP in VL206 was within the range recorded for various landraces (3.61%), DMD value (27.29%) was lower than that of all the landraces tested. In saceo DMD data indicate that the fodder quality of landraces is better than that of the introduced variety. The values for neutral detergent fibre (NDF) ranged from 63.64% (Sabhawati) to 78.46% (Chhotiya) among the rainfed landraces, while in the irrigated landraces, Thapchini had more NDF (87.50 %), as compared to Kantolia (73.88%) and VL206 (74.91%). Values for the acid detergent fibre (ADF) varied from 42.70% (Danbasmati) to 54.58% (Nandhani) in the rainfed group; ADF was slightly higher in Thapchini (49.41%) in comparison to Kantolia (47.19) and VL206 had the highest (56.80%) ADF content. The observed differences with respect to straw productivity, chemical composition and in saceo DMD in various landraces, even when grown under similar conditions at one place, clearly indicate the richness of the gene pool of rice being maintained, through cultivation, in the Kumaun hills. It may be mentioned that agriculture in the hills is biomass based, and livestock form an integral component of subsistence farming.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号