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481.
土壤动物群落生态学与土壤微生态环境的关系   总被引:3,自引:0,他引:3  
主要综述了国内外蚯蚓种群、捕食性线虫、蚂蚁、跳虫、螨类等土壤动物与土壤理化性质的关系,以及蚯蚓、白蚁、蜗牛、线虫等土壤动物与土壤酶活性的相关性研究;提出了该学科今后的研究趋势。该学科未来要融合土壤动物和整个农林生态系统的研究为一体,把农林的土壤动物群落生态学及其与土壤微生态环境关系结合起来,耦合土壤动物与植物根系-根际微生态环境,链接农林土壤动物与土壤健康及其害虫生态调控,分析探究它们内在的联系和机制,加强立地调控措施,为森林健康和土壤健康提供科学基础资料。  相似文献   
482.
关于蔬菜施有机肥和它与无机肥的合理配施比例,对蔬菜的产量和品质有重要影响,对土壤有机质和重金属含量也有影响。为控制施禽畜粪类有机肥对蔬菜的负面影响,探讨蔬菜的合理施用量和有机/无机肥配施比例,在不同质地的土壤上进行田间试验。结果表明,(1)施过量禽畜粪类有机肥对试验蔬菜产量和品质都会产生不良影响,小白菜(Brassica chinensis)和茄子(Eggplant)施禽畜粪超过22500kg/hm2、马铃薯(Solanum tuberosum L.)超过24000kg/hm2时,其产量不再增加,成活率下降,维生素C含量下降,多个试验均表现出有机肥用量增加而小白菜硝酸盐随之增加的典型特征;同时不论土壤的质地轻重,蔬菜重金属Pb有随禽畜粪用量增加而提高的趋势;在质地较轻的土壤上,蔬菜重金属Cd、As有随禽畜粪用量增加而提高的趋势;小白菜施禽畜粪肥超过7500kg/hm2、茄子和冬种马铃薯施禽畜粪肥超过75000kg/hm2,收获后土壤重金属含量高于对照和施无机肥的总Cr和As。(2)蔬菜单独施用有机肥的合适施用量,小白菜在较粘重的土壤上可施到22500kg/hm2,但有机肥与无机肥配合施用时有机肥用量可减量;茄子合适施用量应在22500kg/hm2左右;冬种马铃薯合适施用量应在24000kg/hm2左右。(3)蔬菜的有机/无机肥合理配比,小白菜、茄子、和冬种马铃薯施肥的有机氮与无机氮之比均为0.25∶1至0.5∶1时其产量和品质水平较佳。  相似文献   
483.
调查了宁夏青铜峡贺兰山东麓冲积、洪积的干旱荒漠草原约200km2的水氟、表层土壤水溶氟、牧草氟、大气含氟量和在当地放牧的牧羊业受氟害的情况。结果表明.这里的水氟、土壤水溶氟、牧草含氟量等均比氟安全区偏高,属自然高氟地区。自然高氟地区对牧羊业的危害-主要使母羊寿命比氟安全区约减少一半而造成经济损失,经估算每平方千米约损失380元。  相似文献   
484.
A couple of experiments were conducted to estimate the optimal temperature effect on growth of Chinese shrimp (Penaeus chinensis). The equation describing growth-temperature relationship derived from the first experiment with temperature ranging from 16° to 31°C was found linear as the following:
G = -0.005667 + 0.001103 T
,where G and T are daily growth rate and temperature, respectively.The second experiment indicated that the daily growth rate was a quadratic function of temperature at the limits of 27° and 35°C. The equation was
G = -0.339587 + 0.023476 T − 0.000375 T2
.The optimal temperature in terms of maximum growth was 31.26°C.  相似文献   
485.
草原生态保护补助奖励政策在阿勒泰地区的实施,标志着该地区草原生态保护进入兼顾民生的发展时期。该地区的政策实施取得了一定的成效,但是还存在补偿标准低、草畜平衡难度大、基本规章制度尚未完善、配套设施及项目资金滞后、农牧民缺乏现代科学技术等问题。造成这些问题的原因有:草地牧草总产量和实际放牧量难以掌控;法律机制不完善;草原产权不清晰;草原生态建设的投融资机制不完善;生态保护观念尚未建立;农业转型困难等。  相似文献   
486.
动物伦理学研究   总被引:1,自引:0,他引:1  
为了构建动物伦理学,笔者考察并概括了西方动物伦理研究的本质和关键问题,认为:动物伦理学是关于人与动物关系的伦理信念、道德态度和行为规范的理论体系,是一门尊重动物的价值和权利的新的伦理学说。它的产生具有坚实的科学基础、伦理基础和现实迫切性。  相似文献   
487.
After satisfying their quantitative and qualitative needs as regards nutrition, consumers in developed countries are becoming more involved in the ethical aspects of food production, especially when it relates to animal products. Social demands for respecting animal welfare in housing systems are increasing rapidly, as is social awareness of human responsibility towards farm animals. Many studies have been conducted on animal welfare measurement in different production systems, but the available information for small ruminants remains insufficient. In this study, a 75 criteria-evaluation tool has been set up on the basis of the five freedoms concept. Animal welfare considerations have been analyzed in 25 documents, including labeling schemes, regulations, and recommendations from different European countries. The results show many differences between regular and organic small ruminant farming standards. Emergency measures are generally lacking. A weak representation of psychological aspects of animal welfare, especially by the current European legislation, is highlighted.  相似文献   
488.
Estimation of Nitrous Oxide Emissions from US Grasslands   总被引:2,自引:0,他引:2  
2 O) emissions from temperate grasslands are poorly quantified and may be an important part of the atmospheric N2O budget. In this study N2O emissions were simulated for 1052 grassland sites in the United States using the NGAS model of Parton and others (1996) coupled with an organic matter decomposition model. N2O flux was calculated for each site using soil and land use data obtained from the National Resource Inventory (NRI) database and weather data obtained from NASA. The estimates were regionalized based upon temperature and moisture isotherms. Annual N2O emissions for each region were based on the grassland area of each region and the mean estimated annual N2O flux from NRI grassland sites in the region. The regional fluxes ranged from 0.18 to 1.02 kg N2O N/ha/yr with the mean flux for all regions being 0.28 kg N2O N/ha/yr. Even though fluxes from the western regions were relatively low, these regions made the largest contribution to total emissions due to their large grassland area. Total US grassland N2O emissions were estimated to be about 67 Gg N2O N/yr. Emissions from the Great Plains states, which contain the largest expanse of natural grassland in the United States, were estimated to average 0.24 kg N2O N/ha/yr. Using the annual flux estimate for the temperate Great Plains, we estimate that temperate grasslands worldwide may potentially produce 0.27 Tg N2O N/yr. Even though our estimate for global temperate grassland N2O emissions is less than published estimates for other major temperate and tropical biomes, our results indicate that temperate grasslands are a significant part of both United States and global atmospheric N2O budgets. This study demonstrates the utility of models for regional N2O flux estimation although additional data from carefully designed field studies is needed to further validate model results.  相似文献   
489.
ABSTRACT: Application of fertilizer can degrade quality of runoff, particularly during the first post-application, runoff-producing storm. This experiment assessed and compared runoff quality impacts of organic and inorganic fertilizer application for a single simulated storm occurring seven days following application. The organic fertilizers used were poultry (Gallus gallus domesticus) litter, poultry manure, and swine (Sus scrofa domesticus) manure. All fertilizers were applied at an application rate of 217.6 kg N/ha. Simulated rainfall was applied at 50 mm/h for an average duration of 0.8 h. Runoff samples were collected, composited, and analyzed for nitrate N (NO3-N), ammonia N (NH3-N), total Kjeldahl N (TKN), ortho-P (PO4-P), total P (TP), chemical oxygen demand (COD), total suspended solids (TSS), fecal coliforms (FC), and fecal streptococci (FS). Application of the fertilizers did not alter the hydrologic characteristics of the receiving plots relative to the control plots. Concentrations of fertilizer constituents were almost always greater from treated than from control plots and were usually much greater. Flow-weighted mean concentrations of NH3-N, PO4-P, and TP were highest for the inorganic fertilizer treatment (42.0, 26.6, and 27.9 mg/L, respectively). Runoff COD and TSS concentrations were greatest for the poultry litter treatment. Concentrations of FC and FS were greater for fertilized than for control plots with no differences among fertilized plots, but FC concentrations for all treatments were in excess of Arkansas' primary and secondary contact standards. Mass losses of fertilizer constituents were low (≤ 3 kg/ha) and were small proportions (≤ 3 percent) of amounts applied.  相似文献   
490.
近30年青海三江源西部干旱区草地退化特征的遥感分析   总被引:4,自引:2,他引:2  
使用自20世纪70年代末~2004年的3期遥感图像(70sMSS、90sTM和2004年TM/ETM),研究了近30年青海三江源西部干旱区草地退化的格局与过程,结果表明:整个研究时段内,草地退化发生面积占总草地面积的10%左右,且以草地覆盖度轻度下降为主,其退化面积占总草地退化面积的80%以上,其次是轻度沙化/盐化,相应比重占10%以上。草地退化面积呈东南向西北减少趋势,退化程度呈东南向西北降低格局,而退化类型也由复合型向单一型过渡。整个时段内,草地退化面积呈增加趋势,尤其是沙化面积增加较快。不同海拔、坡度和坡向间草地退化面积差异显著。海拔4 800~5 100m范围内为草地退化发生的主要分布区,4 500~4 800m和5 100m以上草地退化基本相当。退化率较高的坡度级别介于2~8°之间,类似于草地面积随坡度变化的基本趋势。不同坡向呈阴坡、半阴半阳坡高于阳坡的态势。脆弱的基底、极端气候年际间周期波动等限制性因子控制着草地退化的基本格局,人为扰动则决定草地退化的强度和速度。总体看来,研究区地带性自然条件决定的荒漠化草地已占据主导地位,人类活动相对较弱,草地退化程度增加趋势不明显,新的草地退化现象不十分突出。  相似文献   
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