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   132篇
  免费   12篇
  国内免费   10篇
安全科学   5篇
废物处理   1篇
环保管理   48篇
综合类   34篇
基础理论   48篇
污染及防治   8篇
评价与监测   2篇
社会与环境   5篇
灾害及防治   3篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2020年   4篇
  2019年   4篇
  2018年   3篇
  2017年   5篇
  2016年   5篇
  2015年   2篇
  2014年   5篇
  2013年   13篇
  2012年   5篇
  2011年   8篇
  2010年   7篇
  2009年   9篇
  2008年   2篇
  2007年   7篇
  2006年   7篇
  2005年   10篇
  2004年   7篇
  2003年   4篇
  2002年   3篇
  2001年   4篇
  2000年   2篇
  1999年   9篇
  1998年   5篇
  1997年   5篇
  1996年   3篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1986年   1篇
  1979年   1篇
  1975年   1篇
排序方式: 共有154条查询结果,搜索用时 31 毫秒
111.
峨眉山野生观赏蕨类资源及其开发利用   总被引:2,自引:0,他引:2  
峨眉山野生蕨类植物资源十分丰富,有540余种,其中具有较高观赏价值的有104种,分别隶属于36科60属。对峨眉山的野生观赏蕨类植物资源的生长类型、观赏价值及其分布作了介绍,并对峨眉山观赏蕨类资源的开发利用提出了建议。  相似文献   
112.
为深入了解盐胁迫下外源硅(Si)对水稻种子萌发的作用,采用溶液培养法研究了外源Si对盐胁迫下野生型和硅突变体水稻(不能正常吸收Si)种子萌发各指标的影响.结果表明,随着NaCl浓度的提高(0~150mmol·L-1),两种水稻的芽长、发芽势、发芽率均不断降低.在150mmol·L-1NaCl胁迫下,野生型和硅突变体水稻的芽长分别为0.33cm和0.55cm,仅为对照的8.0%和11.1%;发芽率仅为对照的29.7%和53.7%;发芽势则分别降低至0%和2%.外源Si可以提高盐胁迫下两种水稻的发芽指标,且对硅突变体水稻的影响显著大于野生型水稻.2mmol·L-1Si浸种+2mmol·L-1Si处理可使野生型水稻芽长、芽重和发芽率分别比对照增加127.27%、169.23%和55.17%,发芽势则由对照时的0%提高至23.33%;硅突变体水稻芽长、芽重和发芽率分别比对照增加307.27%、285.71%和80.29%,发芽势则由对照时的2%提高至82.22%.  相似文献   
113.
云南省野生禾本科干燥花资源   总被引:4,自引:0,他引:4  
调查研究了产于云南的野生禾本科干燥花资源,共筛选出60种干燥花,并对数种重要干燥花资源进行了简要评述。  相似文献   
114.
新冠肺炎疫情的发生暴露了我国野生动物保护立法在禁止食用野生动物源头制度设计上的不足,引发了社会舆论对“全面禁止食用野生动物”的强烈呼吁。审视我国《野生动物保护法》,立法目的理念中并没有体现保障公众健康的内容;对捕食野生动物没有采取完全禁止的态度,而是根据野生动物的珍稀、濒危程度,生态、科学、社会价值,以及是否为人工繁育等多重标准,分别采取了禁止食用、限制食用、特别许可、支持利用等不同的措施,存在失之过宽的问题;野生动物保护范围不周延,一些可能引发疫病传播的野生动物没有纳入保护范围。回应社会关切,对立法中存在的问题进行理性分析,应当尽快修改《野生动物保护法》,矫正立法目的理念,体现对公众健康安全的保障;扩大野生动物的保护范围,并制定相应的管制规范;实现相关立法的衔接,建立以“全面禁止食用为原则,分类限制禁止食用为补充”的野生动物风险防范制度。从源头上防范野生动物病毒传播引发重大公共卫生风险,实现保护野生动物与保障公众健康安全的有机统一。  相似文献   
115.
为合理开发利用九阜山省级自然保护区野生兰科植物资源,对该区野生兰科植物资源进行了调查。结果表明,该区共有野生兰科植物12属16种,列出了该区每种野生兰科植物的属名、学名、生活型、主要用途、生境及其分布海拔,对其种类组成、属的分布区类型、生活型、生态环境、开发利用价值、资源分布与贮量进行了分析,提出了保护与开发利用措施。  相似文献   
116.
野生食用菌资源是云南省山区农村重要的非木材林产品资源,加强对当地野生食用菌资源的管理、实现可持续利用已成为一个重要课题。对云南省小哨生态村承包山林拾菌这种可持续资源利用管理模式进行了深入分析和探讨,目的在于通过典型案例的研究,为云南省丰富的野生食用菌资源的管理和可持续利用提供思路。  相似文献   
117.
Summary. We characterized the induction of hydroxamic acids (Hx) by aphid infestation in the wild wheat Triticum uniaristatum by addressing the following questions: i) Do different leaves have similar responses to aphid damage?, ii) Is the Hx induction localized or systemic?, iii) How long does the induction last?, and iv) Is the degree of damage related to the magnitude of induced Hx? Based on earlier results on this wheat/aphid system (lack of costs of Hx induction) we expected to find the plant exhibiting cost-saving patterns of response to herbivory. Aphid infestation in the primary leaf led to induced levels of Hx, but no differences in Hx levels were found after infestation of the secondary leaf. Induction of Hx was restricted to the infested leaf (primary leaf). Induced Hx levels exhibited by the primary leaf at the end of aphid infestation were not observed 2 days later. Finally, different aphid densities (between 10 and 40 aphids per leaf) did not produce significant differences in Hx levels in infested primary leaves. Characteristics of Hx induction by aphid infestation in T. uniaristatum partially support the expected cost-saving patterns in the allocation of induced defenses. Received 15 January 1997; accepted 7 July 1997.  相似文献   
118.
Baltic salmons were caught from two Latvian rivers during the spawning seasons of 2010 and 2011 for the determination of seventeen 2,3,7,8-chlorine-substituted dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (PCBs). A partially automated clean-up procedure was used for sample preparation, followed by capillary gas chromatography hyphenated to high-resolution mass spectrometry. The concentrations of PCDD/F&;PCB-TEQ ranged from 6.6 to 18.2?ng?kg?1 fresh weight and this confirms the previous reports of relatively high concentrations of PCDD/Fs, and especially of dioxin-like PCBs in Baltic wild salmon, in most samples exceeding maximum recommended levels (MRLs) in toxicity equivalency quotients (PCDD/F-PCB-TEQ) of the World Health Organization (WHO 1998) according to EC COMMISSION REGULATION No 1881/2006. The results suggest that high consumption of Baltic wild salmon could entail the risk of exceeding the TDI for adults and teenagers. Extra care must be taken when Baltic wild salmon is included in childrens's diet to avoid exceedance of the recommended TDI of 4?pg?kg?1 body weight for this group.  相似文献   
119.
Essential and toxic elements were determined by Energy Dispersive Polarized X-Rays Fluorescence Spectrometry (EDPXRF) in the meat of 145 wild and bred animals to provide the baseline data regarding meat of wild and bred animals consumed in central Italy. As far as K, Fe, Ni, Zn, and Cu are concerned, no significant differences resulted between young and adults and between males and females for farmed and wild animals. No marked differences were found between hunted and non-hunted animals groups. In all samples analyzed, Mn, Cr, and Mo were below the detection limit. As far as the non-essential or toxic elements are concerned, As, Cd, V, and Hg concentrations in muscle from wild and bred animals were low and always below the detection limits. Among the wild animals killed with lead (Pb) bullets, elevated Pb concentrations in tissues were detected. This finding may result in elevated Pb levels in meat ingested by humans.  相似文献   
120.
The objective of the present study was to investigate the levels of Cd, Pb, Co, and Cu, in A. chukar, A. griseogularis, and Columba livia, in order to (1) examine the age- and gender-related variation in trace metal accumulation and (2) to determine the significance between metal concentrations in the kidney, liver, and pectoral muscle. Mean concentrations of Cd and Pb in the kidney of A. chukar, A. griseogularis, and C. livia were 3.7, 4.1, and 3.9?µg/g and 15.9, 13.6, and 15.5?µg/g, respectively. In the liver, they were 4.8, 4.3, and 3.9?µg/g and 21.4, 21.3, and 21.1?µg/g, and in the pectoral muscle, 2.3, 2.3, and 2.2?µg/g and 7.1, 7.1, and 7.8?µg/g, respectively. Metal concentrations in three bird species were decreased in the sequence of liver?>?kidney?>?pectoral muscle. Trace metal concentrations in the three species were higher in females than in males. The mean concentrations of Cd in the kidney and liver were higher than the background levels, as well as Pb concentrations in the liver were higher than the toxic level.  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