全文获取类型
收费全文 | 2497篇 |
免费 | 159篇 |
国内免费 | 940篇 |
专业分类
安全科学 | 232篇 |
废物处理 | 135篇 |
环保管理 | 193篇 |
综合类 | 1540篇 |
基础理论 | 444篇 |
污染及防治 | 701篇 |
评价与监测 | 129篇 |
社会与环境 | 128篇 |
灾害及防治 | 94篇 |
出版年
2024年 | 13篇 |
2023年 | 73篇 |
2022年 | 142篇 |
2021年 | 149篇 |
2020年 | 124篇 |
2019年 | 106篇 |
2018年 | 122篇 |
2017年 | 137篇 |
2016年 | 100篇 |
2015年 | 155篇 |
2014年 | 201篇 |
2013年 | 207篇 |
2012年 | 219篇 |
2011年 | 218篇 |
2010年 | 157篇 |
2009年 | 153篇 |
2008年 | 192篇 |
2007年 | 137篇 |
2006年 | 147篇 |
2005年 | 86篇 |
2004年 | 60篇 |
2003年 | 84篇 |
2002年 | 88篇 |
2001年 | 86篇 |
2000年 | 63篇 |
1999年 | 55篇 |
1998年 | 51篇 |
1997年 | 43篇 |
1996年 | 51篇 |
1995年 | 36篇 |
1994年 | 38篇 |
1993年 | 21篇 |
1992年 | 20篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有3596条查询结果,搜索用时 866 毫秒
521.
Green shipping practices in the shipping industry: Conceptualization, adoption, and implications 总被引:1,自引:0,他引:1
Kee-Hung Lai Venus Y.H. LunChristina W.Y. Wong T.C.E. Cheng 《Resources, Conservation and Recycling》2011,55(6):631-638
There have been increasing concerns about the adverse impacts on the environment caused by cargo movement in international trade. Different stakeholders ranging from shippers and carriers to government bodies and international communities have expressed worries about the environmental impacts brought by shipping related activities. The pollution and waste created in the shipping processes have imposed environmental burdens and accelerated resource depletion. The situation is set to worsen in the face of intensifying trade globalization, which has contributed to sustained growth in international shipping activities. To help protect the environment, many shipping firms have taken the initiative to find ways to lessen the environmental damage of their operations while enhancing their performance. The objective of this study is to examine the environmental awareness and the environmental measures taken in the shipping industry. We propose a conceptual framework for evaluating green shipping practices and develop several propositions stating the conditions under which shipping firms would behave in an environmentally responsible manner. We conclude with managerial and policy implications of the conceptual framework to promote green shipping practices in the shipping industry. 相似文献
522.
Yi-Huey?Chen Wei-Chun?Cheng Hon-Tsen?YuEmail author Yeong-Choy?KamEmail author 《Behavioral ecology and sociobiology》2011,65(12):2329-2339
The rhacophorid frog, Kurixalus eiffingeri, is one of only a few frog species that exhibits polyandry and paternal care of eggs. Previous studies predicted that multiple
paternity within an egg clutch could influence the degree of paternal care and reproductive strategies. We used microsatellite
DNA markers to assess the prevalence of multiple paternity within egg clutches and the relationship between male paternal
care and the percent of male’s genetic contribution to the clutch, i.e., paternal share. We conducted field observations of paternal care and collected tissues from both male frogs and tadpoles
for parentage analyses. Our results showed that at least five out of 31 egg clutches had multiple paternity. Attending males
were always the genetic fathers of some, if not all of the eggs in the clutch they guarded. All egg clutches except one were
attended by one male frog but the attending male did not necessarily sire the majority of offspring. Multiple paternity in
all cases consisted of two fathers and one mother and most likely resulted from synchronous polyandry. Paternal care effort
correlated significantly with the male’s genetic contribution to the clutch, suggesting that male frogs adjust the effort
expended in care in response to paternal share. In addition, our results suggest that externally fertilizing species with
parental care and multiple paternity may develop novel reproductive and behavioral strategies to safeguard their parental
investment and overcome sperm competition. 相似文献
523.
Huei-Jen Tseng Ren-Chung Cheng Sheng-Hai Wu Sean J. Blamires I-Min Tso 《Behavioral ecology and sociobiology》2011,65(12):2351-2359
Animals may build multiple structures to provide benefits to counter the costs of building. Many orb web spiders add multiple
structures, e.g., barricading barrier webs and silk decorations, to their webs and these structures have been hypothesized
to function to deter predators or attract prey. The heavily armored spiny spiders construct barrier webs around their orb
webs and decorate them with conspicuous silk tufts. Why these organisms, already well protected by a thick cuticle and spines,
make the extra investment of building barrier webs and adding conspicuous silk decorations is not known. We predicted that
these structures function to both attract prey and deter predators. Field experiments were conducted in two consecutive years
using orb webs built by the East Asian spiny spider Thelacantha brevispina. We either (1) concealed the decoration, (2) removed the barrier webs, or (3) left the decorations and barrier webs intact.
We found year and treatment to interactively influence prey interception rates. In 2010, but not in 2009, we found prey interception
with T. brevispina webs to be greater when the decorations were conspicuous than when they were concealed suggesting that the decorations may
lure prey. Prey interception was lower when the barrier webs were present without decorations compared to when they were absent
without decorations. The prey-attracting function of the decorations thus may counter the reduction in prey interception incurred
by adding a barrier web. Predatory wasp interactions were not influenced by any of our treatments, probably because the spiders’
thick cuticle is the primary means of protection from wasps. Bird predation events, while rare, occurred only when decorations
were concealed or the barrier webs were removed. It is therefore plausible that the tuft decorations both lure prey and deter
birds. 相似文献
524.
北京建成区道路绿化空间结构和行道树健康状况 总被引:2,自引:0,他引:2
采用实地普查测量方法,定量研究了北京建成区188条道路行道树的树种结构、径级分布、立木层次和健康状况。结果表明,国槐(Sophora japonica)、毛白杨(Populus alba)、银杏(Ginkgo biloba)是建成区主要行道树种,使用量分别占研究区树木总株数的54.7%、13.7%和7.4%。建成区树木... 相似文献
525.
贵州浓香型白酒大曲中霉菌的18S rDNA系统发育分析 总被引:4,自引:0,他引:4
从贵州某名酒厂大曲中分离到104株丝状真菌(霉菌),通过形态特征和生理特性检测等传统鉴定方法,初步把形态和生理生化特征一致的霉菌归类为14个大类群;并采用18S rDNA序列分析,进一步把菌株归类为MJ-I至MJ-V五个类群,随后构建系统发育树.结果表明,样品中的霉菌以曲霉属(Aspergillus)为主,占总分离菌数... 相似文献
526.
527.
Xiang Yang Sun Cheng Da Gao Lin Zhang Su Yan Li Yong Qiao 《Environmental monitoring and assessment》2011,175(1-4):193-200
CO2 release from forest soil is a key driver of carbon cycling between the soil and atmosphere ecosystem. The rate of CO2 released from soil was measured in three forest stands (in the mountainous region near Beijing, China) by the alkaline absorption method from 2004 to 2006. The rate of CO2 released did not differ among the three stands. The CO2 release rate ranged from ??341 to 1,193 mg m???2 h???1, and the mean value over all three forests and sampling times was 286 mg m???2 h???1. CO2 release was positively correlated with soil water content and the soil temperature. Diurnally, CO2 release was higher in the day than at night. Seasonally, CO2 release was highest in early autumn and lowest in winter; in winter, negative values of CO2 release suggested that CO2 was absorbed by soil. 相似文献
528.
Shou-Qing Liu Shi Cheng Li Luo Hong-Ying Cheng Song-Jun Wang Shuai Lou 《Environmental Chemistry Letters》2011,9(1):31-35
Rhodamine B can be degraded using Prussian blue as a photo-Fenton like reagent under λ > 420 nm visible irradiation. Kinetic
studies show ln(C
o/C
t
) is linearly proportional to the reaction time during the photo-degradation process; thus, the degradation reaction obeys
a pseudo-first order kinetic law. It is very interesting that the presence of salinity such as 0.1 M KCl can speed up greatly
the degradation rate: the time to achieve 90.0% degradation ratio is shortened from 120.0 to 40.0 min under comparable conditions,
which is very useful in the treatment of wastewaters with high content of salinity. 相似文献
529.
顶板瓦斯高抽巷合理抽放负压数值模拟研究 总被引:1,自引:0,他引:1
顶板瓦斯高抽巷的抽采效果与抽放负压直接相关.结合阳煤三矿K8206大采长综放 面顶板瓦斯高抽巷实际抽采效果,通过数值模拟与现场实测数据分析,得出顶板瓦斯高抽巷 抽采正常期最优抽放负压,以期对高瓦斯矿区顶板瓦斯高抽巷的合理抽放参数确定提供科学依据,实现矿井的煤与瓦斯安全高效共采. 相似文献
530.
Ming-Lang Tseng Lawrence W. Lan Ray Wang Anthony Chiu Hui-Ping Cheng 《Environmental monitoring and assessment》2011,175(1-4):367-385
Green performance measure is vital for enterprises in making continuous improvements to maintain sustainable competitive advantages. Evaluation of green performance, however, is a challenging task due to the dependence complexity of the aspects, criteria, and the linguistic vagueness of some qualitative information and quantitative data together. To deal with this issue, this study proposes a novel approach to evaluate the dependence aspects and criteria of firm??s green performance. The rationale of the proposed approach, namely green network balanced scorecard, is using balanced scorecard to combine fuzzy set theory with analytical network process (ANP) and importance-performance analysis (IPA) methods, wherein fuzzy set theory accounts for the linguistic vagueness of qualitative criteria and ANP converts the relations among the dependence aspects and criteria into an intelligible structural modeling used IPA. For the empirical case study, four dependence aspects and 34 green performance criteria for PCB firms in Taiwan were evaluated. The managerial implications are discussed. 相似文献