全文获取类型
收费全文 | 4882篇 |
免费 | 656篇 |
国内免费 | 2886篇 |
专业分类
安全科学 | 342篇 |
废物处理 | 255篇 |
环保管理 | 417篇 |
综合类 | 4747篇 |
基础理论 | 1110篇 |
环境理论 | 1篇 |
污染及防治 | 1154篇 |
评价与监测 | 263篇 |
社会与环境 | 115篇 |
灾害及防治 | 20篇 |
出版年
2024年 | 10篇 |
2023年 | 98篇 |
2022年 | 192篇 |
2021年 | 263篇 |
2020年 | 204篇 |
2019年 | 268篇 |
2018年 | 272篇 |
2017年 | 256篇 |
2016年 | 316篇 |
2015年 | 357篇 |
2014年 | 413篇 |
2013年 | 481篇 |
2012年 | 577篇 |
2011年 | 575篇 |
2010年 | 452篇 |
2009年 | 545篇 |
2008年 | 365篇 |
2007年 | 391篇 |
2006年 | 440篇 |
2005年 | 312篇 |
2004年 | 248篇 |
2003年 | 247篇 |
2002年 | 202篇 |
2001年 | 179篇 |
2000年 | 156篇 |
1999年 | 118篇 |
1998年 | 92篇 |
1997年 | 77篇 |
1996年 | 78篇 |
1995年 | 63篇 |
1994年 | 42篇 |
1993年 | 37篇 |
1992年 | 32篇 |
1991年 | 21篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有8424条查询结果,搜索用时 46 毫秒
751.
本文主要介绍了美国海军现用的工作服装种类、服装构成及穿着场合,并与我国海军07式作训服进行了对比分析。 相似文献
752.
753.
产酸脱硫反应器中碳硫比对群落生态特征的影响 总被引:10,自引:1,他引:9
通过产酸脱硫反应器处理高浓度含硫酸盐废水的连续流试验,从群落动态的角度研究碳硫比(COD/SO42-)从4.2降低到2.0的过程中,pH值、氧化还原电位(ORP)、碱度(ALK)和末端产物(VFAs)组成、优势种群分布等群落生态特征的变化规律试验证明,在此过程中ORP和ALK提高,而pH值和VFAs中乙酸的分布比例降低,群落类型由高碳硫比稳定型转化为低碳硫比亚稳定型,但仍未改变乙酸型顶极群落的典型特征. 相似文献
754.
755.
This paper documents the effect of primary forest cover loss on increased incidence of malaria. The evidence is consistent with an ecological response. I show that land use change, anti-malarial programs or migration cannot explain the effect of primary forest cover loss on increased malarial incidence. Falsification tests reveal that the effect is specific to malaria, with forest cover having no discernible effect on other diseases with a disease ecology different from that of malaria. Back-of-the-envelope calculations indicate that the morbidity-related malaria-reducing local benefits of primary forests are at least $1-$2 per hectare. 相似文献
756.
磷系阻燃剂对人体的潜在毒性作用引起了国内外研究者的广泛关注。肾脏是机体重要的排毒器官,若肾脏细胞受损,可能影响肾脏功能的正常发挥。本研究以人胚肾细胞HEK293为研究对象,结合传统毒理学实验,筛选出磷酸三苯酯(TPP)及磷酸三(2-氯异丙基)酯(TCPP)诱导人胚肾细胞HEK293凋亡的关键靶标基因p53。在此基础上采用分子对接模拟和光谱法分析发现,TPP和TCPP分别以嵌插方式和沟槽方式结合p53-DNA,改变基因片段的框架结构,启动分子起始事件,通过影响相关基因(Bax、Hrk、Bcl-2和Bad)的表达量,导致线粒体途径释放cyt c,最终激活Caspase 7实现细胞凋亡。研究结果阐明了此类污染物诱导凋亡的作用机制,为毒害化学品的污染防控提供理论依据。 相似文献
757.
Dian Ding Jia Xing Shuxiao Wang Xing Chang Jiming Hao 《Frontiers of Environmental Science & Engineering》2019,13(5):76
758.
The present paper addresses two policy objectives: to implement a market for pollution permits and to make regulation acceptable for businesses. Profit-neutral permit allocations are defined as the number of permits that the regulator should give for free so that post-regulation profits (i.e. a firm's profits in the products market plus the value of the allowances granted for free) are equal to pre-regulation profits. The proposed model is developed by assuming that firms use polluting technologies and compete “à la Cournot”. The paper demonstrates that a low number of free allowances is sufficient to meet these two goals. Moreover, the regulator can fully offset losses, even when the reduction in emissions is high, provided that the sectors concerned are not monopolies, both for isoelastic and linear demand functions. 相似文献
759.
This paper analyzes the energy price-employment nexus and contributes to the literature by showing that it is important to decompose the regulatory effect into demand, cost, and factor-shift effects. This is done by means of a cross-country multi-sectoral dataset. The results show that both rising energy prices and shadow prices of energy have no significant effect on net employment when the manufacturing sectors only are analyzed. While finding significant variations across countries, the average employment effects become significantly positive once jobs in the economy as a whole are considered. This change is driven mainly by larger positive cost effects, which more than offset the negative demand effects and reductions in the positive factor-shift effects. Moreover, the paper reveals that the often implemented approach of using a simple regulation regressor, instead of decomposing the employment effect, can result in biased estimates. 相似文献
760.
Economic growth,international trade,and the depletion or conservation of renewable natural resources
Conservation of renewable natural resources and promotion of economic growth are both sustainable development goals. Here, we study the interdependency between economic growth, international trade, and the use of renewable natural resources—under alternative institutional settings of either open access or full property rights—in an endogenous growth model. We find that if the resource is depleted over time, consumption growth is reduced. Economic growth and international trade only impact resource use when the resource is harvested under full property rights. Then, widening international trade can lead countries to shift from conservation to depletion. Changes in the institutional setting of resource use in one country may have repercussions on trading partners. Our results indicate potential trade-offs between the sustainable development goals and imply that policies focusing on resource use or trade (e.g., international trade bans or certified trade) are not sufficient to prevent resource depletion. 相似文献