全文获取类型
收费全文 | 993篇 |
免费 | 76篇 |
国内免费 | 328篇 |
专业分类
安全科学 | 80篇 |
废物处理 | 25篇 |
环保管理 | 259篇 |
综合类 | 548篇 |
基础理论 | 236篇 |
污染及防治 | 116篇 |
评价与监测 | 90篇 |
社会与环境 | 41篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 29篇 |
2020年 | 29篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 30篇 |
2016年 | 40篇 |
2015年 | 62篇 |
2014年 | 50篇 |
2013年 | 74篇 |
2012年 | 55篇 |
2011年 | 71篇 |
2010年 | 55篇 |
2009年 | 55篇 |
2008年 | 47篇 |
2007年 | 86篇 |
2006年 | 76篇 |
2005年 | 62篇 |
2004年 | 48篇 |
2003年 | 60篇 |
2002年 | 52篇 |
2001年 | 39篇 |
2000年 | 40篇 |
1999年 | 36篇 |
1998年 | 41篇 |
1997年 | 29篇 |
1996年 | 21篇 |
1995年 | 22篇 |
1994年 | 15篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有1397条查询结果,搜索用时 31 毫秒
881.
经C60、N-甲基甘氨酸和间硝基苯甲醛反应得到N-甲基-2-(3-硝基苯基)吡咯烷[3′,4′∶1,2][60]富勒烯(MNPF)反应液,旋转蒸发干燥得质量分数为23%的MNPF粗品,采用柱色谱法批量分离其中的MNPF。确定了柱色谱法批量分离MNPF的最佳工艺条件:二硫化碳为流动相,柱层析用硅胶(37~48μm)为固定相,色谱柱直径5cm,高径比为6∶1,最大上样量为23 g。此时分离所得MNPF纯度达99%,回收率为92.3%。 相似文献
882.
三亚市水体中PPCPs的污染水平、分布特征及生态风险评价 总被引:4,自引:4,他引:0
环境中药物和个人护理用品(PPCPs)污染已引起全球性的关注,为了解热带滨海旅游城市三亚市的河流及主要海湾中PPCPs的污染水平、空间分布特征及其潜在环境风险,采用固相萃取和高效液相色谱串联质谱测定了三亚市主要河流和海湾中的11种典型PPCPs类物质.结果表明,由于三亚市在冬季和夏季接待旅游人数和降雨量的季节性变化,以及在冬季大量涌入以老年人为主的"候鸟"人口,使得三亚市主要河流中PPCPs浓度的季节性差异显著.冬季11种PPCPs检出率为100%,咖啡因(CFI)检出浓度最高为1449.10 ng·L-1,其次为美托洛尔(MTP)检出浓度最高为427.06 ng·L-1和罗红霉素(RTM)检出浓度最高为311.59 ng·L-1;夏季除磺胺甲唑(SMX)、磺胺噻唑(STZ)、泰乐菌素(TYL)、MTP和卡马西平(CBZ)的检出率在87.5%~93.75%,其余检出率为100%,CFI、MTP、RTM、红霉素(ETM)和氧氟沙星(OFL)浓度较高.主要海湾近岸海水中11种PPCPs均有检出,其中SMX、MTP和CBZ的检出率分别为85.7%、57.1%和71.4%,其余PPCPs检出率均为100%.CFI检出浓度最高,最大浓度为220.78 ng·L-1.运用风险商值模型(RQ)评价11种PPCPs在三亚市河流生态环境中的潜在风险,发现冬季STZ在月川桥采样点和RTM在凤凰路采样点,由于附近的医院以及污水处理厂出水排入,RQ值均>l,对水体的生态环境存在高风险.在夏季STZ在三亚大桥采样点、RTM在红沙码头采样点的RQ值介于0.1~1之间,对水体的生态环境具有潜在的中风险. 相似文献
883.
884.
漆酶(p-苯二醇:分子氧氧化还原酶;EC 1.10.3.2)是自然界中普遍存在的一类胞外含铜多酚氧化还原酶.漆酶能够以环境中氧分子作为电子接受体,催化4个底物分子的单电子氧化形成4个相应的反应活性自由基或醌类中间体,随后这些活性中间体在酶促位点外发生步进式偶联反应,生成多种具有复杂结构的大分子C—C、C—O—C或C—N—C共价聚合产物.该反应过程中仅生成唯一副产物水,具有反应温和、底物广谱、催化效率高、操作可控和经济环保等优点.目前,真菌漆酶介导低分子有机物和高分子化合物的自由基偶联和接枝反应已经被应用于生物技术领域,该技术克服了传统物理化学方法存在的弊端,在保护人群健康和生态安全等方面具有广泛地应用前景和商业价值.本文详细地概述了真菌漆酶催化不同底物分子的自由基偶联和接枝反应在环境修复、生物监测、食品加工、纤维改性、纺织染色、制药行业和有机合成等绿色化学中的最新研究进展,旨在为开发和拓展真菌漆酶在绿色化学技术领域中的多功能应用提供科学的理论依据和技术指导. 相似文献
885.
886.
三峡水库蓄水初期水生态环境特征分析 总被引:15,自引:4,他引:11
以2003年10月和2004年4月的两次现场调查数据为基础,分析三峡水库蓄水初期的水生态环境特征。结果表明,蓄水初期水库水体交换能力减弱,水库有机污染甚微,但水体TN、TP浓度偏高,水库整体处于中营养状态;根据水生态环境特征的差异性,水库水域可划分为3种类型区,即坝前水域、库区干流水域以及库区支流洄水河段。对主要影响因素进行分析,发现流速、营养盐含量及水温是影响水生态环境特征的主要因素,而由于各类型区的TP、TN等营养盐含量均较高,水温及流速已成为三峡水库水生态环境特征的控制性因子。探讨3类不同水域的富营养化敏感性,表明坝前水域及库区支流洄水河段是库区未来富营养化的敏感水域。 相似文献
887.
Brydges T 《Environmental monitoring and assessment》2001,67(1-2):89-95
Anthropogenic activities are changing the chemical composition of the global atmosphere. This results in changes to the physical properties as well, such as the radiation balance. These properties are important input variables for biospheric processes. This paper discusses a number of documented ecological changes that have occurred in response to the changing atmosphere. Much of the information has been derived from data collected at integrated monitoring sites. The changing atmosphere is expected to result in many more ecological changes to resources of economic as well as environmental value. Defining and understanding these changes will be necessary for managing sustainable development and poses major challenges for monitoring programs in general and for integrated sites in particular. 相似文献
888.
Mark B. Green Christian H. Fritsen 《Journal of the American Water Resources Association》2006,42(3):659-674
ABSTRACT: Because the Truckee River connects two lakes along the Eastern Sierra Nevada Mountains with different limiting nutrients, this research addresses whether the nitrogen:phosphorus (N:P) balance of the river ecosystem changes longitudinally. Historical (1990 to 2000) total nitro‐gen:total phosphorus (TN:TP) ratios in river water exhibited the expected gradient from high N:P ratios upstream to low N:P ratios downstream, with the major gradient of the N:P balance occurring within the transition between montane and high desert terrain. During 2001, the river contained anomalously low total nitrogen concentrations in the far upper reaches and dissolved inorganic nitrogen concentrations in the lower reaches, resulting in a less apparent longitudinal gradient of N:P ratios. Measurements of periphyton growth and physiology (nutrient bioassays and ectoenzyme activities) and stoichiometry during the summer of 2001 also exhibited a complex picture of the spatial variation of N:P balance that was not entirely consistent with a strong N:P gradient. However, the compendium of the indicators did support the overall picture of an overarching longitudinal gradient from high to low N:P ratios. The results suggest that periphyton management efforts in the Truckee River should consider the overall spatial gradient as well as the small‐scale dynamics of the stream ecosystem structure. 相似文献
889.
李红 《中国环境管理干部学院学报》2005,15(1):121-122
工科有机化学是面向工科专业开设的一门基础课,以往的教学只是按章节顺序详细介绍各类反应,内容多,难以记忆,而且各专业间差别不大.随着教改的不断发展,规定的教学时数愈来愈少,如何解决内容多与时间少的矛盾,如何体现专业特点成为我们急待解决的问题.我们主要从教学目标、教学内容、教学手段方面进行了一些尝试,取得了较好的效果. 相似文献
890.
Perthen-Palmisano B Jakl T 《Environmental science and pollution research international》2005,12(1):49-53
- Sustainable chemistry - Section editors:
Klaus Günter Steinhäuser, Steffi Richter, Petra Greiner, Jutta Penning, Michael AngrickBackground, Aim and Scope Chemicals play a vital role in the day-to-day life of industrialised societies. Their use is not restricted to the chemical enterprises per se, but is a crucial part of production processes in a lot of industrial sectors. Traditional instruments of environmental policy (such as bans, restrictions) can only deal with the most hazardous substances. The Johannesburg Implementation Plan of 2002 calls for more sustainable patterns of production and consumption, and sets the year of 2020 as a goal to use chemicals in a way that human health and the environment are not endangered. Political instruments should not only gather more knowledge about the properties of chemicals, but should also stimulate the environmentally sound use of chemicals. Existing business models should therefore be reviewed in relation to this strategic approach to encourage marketing options with respect to the environmental focus.Main Features Business models were examined for their effects on the consumption of chemicals and amount of waste emissions in relation to their economic potential. Different possibilities for cooperation of supplier, user and disposal companies were elaborated and examined with a view to the specific situation in Austria.Results and Discussion A range of cooperative models summarised under the term ‘chemical leasing’ - was identified, which can contribute to a more efficient use of resources. 12 main possible application areas (cleaning, lubrication, paint stripping and others) have been identified in Austria. If chemical leasing models were applied in these areas, the amounts of chemicals currently used could be reduced by one third (53,000 tonnes per year). Cost reductions of up to 15 % can be expected.Conclusion The application of chemical leasing models can contribute considerably to achieving more sustainable and resource-efficient patterns of production. The Austrian Ministry for Environment has therefore decided to subsidise the further practical implementation of these new service-oriented business models. Pilot projects in 4 enterprises, which are supervised by consulting companies, are currently being carried out. Recommendation and Outlook The experiences of the pilot projects will serve as valuable building blocks for the wider use of chemical leasing models. Furthermore, the UNIDO Cleaner Production Centres have expressed their clear interest and will examine the possibility to use chemical leasing as a part of their Cleaner Production Programmes. 相似文献