全文获取类型
收费全文 | 1104篇 |
免费 | 87篇 |
国内免费 | 246篇 |
专业分类
安全科学 | 325篇 |
废物处理 | 22篇 |
环保管理 | 153篇 |
综合类 | 521篇 |
基础理论 | 227篇 |
污染及防治 | 104篇 |
评价与监测 | 15篇 |
社会与环境 | 43篇 |
灾害及防治 | 27篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 16篇 |
2021年 | 22篇 |
2020年 | 37篇 |
2019年 | 26篇 |
2018年 | 19篇 |
2017年 | 41篇 |
2016年 | 35篇 |
2015年 | 37篇 |
2014年 | 47篇 |
2013年 | 93篇 |
2012年 | 92篇 |
2011年 | 100篇 |
2010年 | 73篇 |
2009年 | 70篇 |
2008年 | 51篇 |
2007年 | 97篇 |
2006年 | 113篇 |
2005年 | 79篇 |
2004年 | 61篇 |
2003年 | 55篇 |
2002年 | 32篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 30篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 31篇 |
1995年 | 19篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1437条查询结果,搜索用时 78 毫秒
941.
Stefan Van Dongen 《Environmental and Ecological Statistics》2006,13(2):213-228
Plant–herbivore interactions are complex and affect herbivore fitness components and life history traits in many different
ways. In this paper, we present results from an experiment studying the effects of leaf quality on pupal survival and duration
of pupation (as measured by time-to-emergence) in the winter moth. Because only surviving pupae are at risk of emerging, analysis
of time-to-emergence should exclude the dead pupae. However, due to right censoring, the survival status could not be determined
for each individual. This failure to determine the group of moths at risk of emerging a priori motivated the development of
a joint model of both survival probability and time-to-emergence. We formulate the model in a Bayesian framework and apply
Monte Carlo Markov Chain (MCMC) to obtain posterior distributions. Time-to-emergence is modeled by a Cox Proportional Hazards
(CPH) model where only the surviving pupae are at risk of emergence. Probability of pupal survival was modeled by a Generalized
Linear Mixed Model (GLMM). The censored individuals were included in the analysis as a missing value in the GLMM. The GLMM
then generated prior distributions of survival probabilties—and thus of the probability of being at risk of emergence—for
these 19 individuals, conditional on the model parameters. The CPH model was formulated as a count process and the binary
frailty was incorporated as a zero-inflated Poisson model. Zeros in this model represent the non-survivors. Leaf quality did
not appear to influence time-to-emergence. Pupal survival was affected in a complex and unexpected way showing opposite effects
in males and females. We also explored the robustness of our model against increased levels of censoring. While the degree
of censoring was low in our study (< 1%), we artificially increased it to 67%. Although further study is required to study
the generality of these results in a theoretical framework, our explorations suggest that the newly proposed technique may
be widely applicable in a variety of situations where the identification of the at risk population cannot be done in a straightforward
way.
Received: January 2005 / Revised: June 2005 相似文献
942.
Effects of the Interactions Between Selenium and Phosphorus on the Growth and Selenium Accumulation in Rice (Oryza Sativa) 总被引:2,自引:0,他引:2
The solution culture, paddy soil culture and the simulation experiments in the laboratory were conducted to clarify the interactions between selenium and phosphorus, and its effects on the growth and selenium accumulation in rice. Results revealed that a suitable supply of selenium could promote rice growth and excessive selenium could injure rice plant, causing lower biomass, especially in the roots. The supply of selenite could enhance the selenium contents of rice shoots and roots in solution culture and in soil culture. The selenium concentrations in roots were much higher than those in shoots supplied with the same rates of selenium and phosphorus. The interaction between selenium and phosphorus was evident. When the phosphorus supply increased to meet the needs of plant growth, phosphorus could promote absorption and accumulation of selenium in the shoots. If the phosphorus supply was excessive, phosphorus could inhibit the accumulation of selenium in the shoots at the lower selenite level (2 mol l–1), but could not at the higher selenite level (10 mol l–1). With the supply of phosphate increased, the selenium concentrations in the roots decreased significantly at both selenite levels. The presence of phosphate could decrease Se sorption on the soil surface and increase the selenium concentration in the soil solution. The concentrations of selenium in shoots and roots supplied with 0.08 g kg–1 phosphorus were lower than those with no phosphorus supplied. With the increase of phosphorus added to 0.4 g kg–1, the selenium concentration in shoots and roots increased. The effect of phosphorus on the concentration was statistically significant at all three selenium levels. 相似文献
943.
944.
利用醋糟开发植物栽培基质的发酵技术 总被引:16,自引:0,他引:16
对利用酿造工业废弃物醋糟开发有机栽培基质的发酵技术进行了试验研究。结果表明:通过加入鸡粪、粉煤灰、石灰水和尿素等碱性物质调节酸度后,能促进醋糟正常发酵,发酵后的产物理化性状均适合于作植物栽培基质。 相似文献
945.
Eric Deleersnijder Jean-Marie Beckers Eric J. M. Delhez 《Environmental Fluid Mechanics》2006,6(1):25-42
The transport from the upper mixed layer into the pycnocline of particles with negative buoyancy is considered. Assuming the
hydrodynamic parameters to be time- independent, an adjoint model is resorted to that provides a general expression of the
residence time in the mixed layer of the constituent under study. It is seen that the residence time decreases as the settling
velocity increases or the diffusivity decreases. Furthermore, it is demonstrated that the residence time must be larger than
z/w and smaller than h/w, where z, h and w denote the distance to the pycnocline, the thickness of the mixed layer and the sinking velocity. In the vicinity of the
pycnocline, the residence time is not necessarily zero; its behaviour critically depends on the eddy diffusivity profile in
this region. Closed-form solutions are obtained for constant and quadratic diffusivity profiles, which allows for an analysis
of the sensitivity of the residence time to the Peclet number. Finally, an approximate value is suggested of the depth-averaged
value of the residence time. 相似文献
946.
马尾松低产林套种木荷的林地与根际土壤养分特性的研究 总被引:1,自引:0,他引:1
傅循晶 《湖南环境生物职业技术学院学报》2003,9(3):189-192
马尾松低产林套种木荷的混交林林地与根际土壤养分特性研究表明,木荷根际对土壤养分的活化能力大于马尾松,这利于混交林中马尾松的生长.套种后所形成的混交林根际微区对土壤养分活化程度的提高改善了两树种的养分利用状况,这可能是低产林改造后林地土壤养分高于纯林地且林分生产力提高的主要原因之一. 相似文献
947.
Ayşe N. Kiraççakali 《Chemistry and Ecology》2020,36(7):651-662
ABSTRACT Deltamethrin is a widely used pyrethroits worldwide. Although the chemical is used to combat insects, it has effects on other non-target organisms. Deltamethrin is extensively used in agriculture, animal husbandry, and domestic areas in the Lake Van basin. The aim of this study was to determine the cytotoxic, genotoxic, and oxidative damage from deltamethrin on the primary hepatocyte culture of Lake Van fish (Alburnus tarichi). In this study, the toxic effects of different concentrations (0.01, 0.1, 1, and 10?µM) of deltamethrin in the primary hepatocyte culture of Lake Van fish were investigated via liver enzymes aspartase aminotransferase (AST) and alanine aminotransferase (ALT), and the total antioxidant status (TAS), total oxidant status (TOS), lipid peroxidation (MDA), and DNA damage (8-OHdG). Deltamethrin caused an increase in the AST and ALT levels dependent on the dosage and time. The TAS and TOS levels increased at the end of 24?h and there was no difference at the end of 48?h. Deltamethrin did not affect the MDA level, but increased the 8-OHdG (P?<?0.05). In conclusion, it can be said that high doses of deltamethrin (1 and 10?µM) have a toxic effect on the primary hepatocyte culture of Lake Van fish. 相似文献
948.
为解决硫糖铝片难于崩解或崩解时限较长的问题.选择混合粘合剂制备硫糖铝片,并考察崩解时限、硬度、脆碎率.结果发现:利用混合剂能明显缩短崩解的时限;利用混合粘合剂制备硫糖铝片达到了预期目的,并为其他片剂在使用粘合剂方面提供参考. 相似文献
949.
以儒家文化为核心内涵的传统主流价值观与中国现代文学的发生、发展有着非常微妙而复杂的联系.一方面,传统主流价值观启示着现代作家在其审美活动中高张“人”的个性,从而实现对传统主流价值的反拨;另一方面又导引着作家以启蒙和救亡为主题担负起对社会的责任与义务,由此而实现对主流价值的归属. 相似文献
950.
注意力经济--文化产业的策略选择 总被引:2,自引:0,他引:2
屈中正 《湖南环境生物职业技术学院学报》2006,12(1):111-113
随着信息技术的无限进展,信息的丰富造成了注意力的贫乏,这是现代社会人民遇到的一个矛盾.作为从计划经济步入市场经济的我国文化产业,已经完全进入市场化的运作,文化产品可经选择的多样性决定了受众的主体地位,大众不再是商家和媒体教育的对象,而是他们的服务对象.我国文化产业要得以长足发展,其首要任务是吸引最大多数人的关注,赢得他们的关心.文化产业的发展需要为大众的注意力买单,要寻找与发掘大众注意力兴奋点,实行吸引受众注意力的产业营销策略.这就是遵从大众认知心理,强化娱乐功能;认同受众的好奇心理,提升品牌形象;紧扣受众的表现心理,倡导时尚消费;认同受众遵从心理,因势利导;巧借受众移情心理,打造个性品牌. 相似文献