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   497篇
  免费   3篇
  国内免费   25篇
安全科学   83篇
废物处理   23篇
环保管理   63篇
综合类   143篇
基础理论   133篇
环境理论   7篇
污染及防治   35篇
评价与监测   9篇
社会与环境   27篇
灾害及防治   2篇
  2023年   18篇
  2022年   11篇
  2021年   25篇
  2020年   28篇
  2019年   16篇
  2018年   24篇
  2017年   37篇
  2016年   37篇
  2015年   35篇
  2014年   48篇
  2013年   89篇
  2012年   6篇
  2011年   17篇
  2010年   10篇
  2009年   13篇
  2008年   9篇
  2007年   9篇
  2006年   8篇
  2005年   12篇
  2004年   15篇
  2003年   13篇
  2002年   9篇
  2001年   6篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1997年   3篇
  1995年   9篇
  1992年   1篇
  1989年   3篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
排序方式: 共有525条查询结果,搜索用时 15 毫秒
101.
Remediation measures for hexavalent chromium [Cr(VI)] are required for a safe environment. As a recent development in microbiology, bacterial biofilms are being studied as effective bioremediation agents. When bacteria are in fungal surface-attached biofilm mode, they are called fungal–bacterial biofilms (FBBs). They have not been tested for bioremediation so far. Hence, this study was conducted to develop FBBs and glass-wool-attached bacterial biofilms (BBs), and to evaluate Cr(VI) tolerability and removal of bacterial monocultures, BBs and FBBs. FBBs showed a significantly high level of Cr(VI) tolerance and resistance compared with its BBs or monocultures. After 10 days, up to 90% of Cr(VI) had been removed, which was significantly higher than that of BBs or its monocultures. Thus, it is clear that FBBs can be used as a novel tool to decontaminate Cr(VI) both in situ and ex situ.  相似文献   
102.
Aim. The purpose of this study was to examine the associations between various health and fitness measures and Functional Movement Screen? (FMS?) scores among 78 firefighter recruits. Methods. Relationships between FMS? scores and age, body mass index (BMI), sit and reach (S&R) distance, estimated maximal aerobic capacity (O2max), estimated one-repetition maximum squat (1RM-Squatmax), and plank endurance (%Plankmax) were examined. Results. Total FMS? scores were significantly correlated with BMI (r?=??0.231, p?=?0.042), estimated 1RM-Squatmax (r?=?0.302, p?=?0.007), and %Plankmax (r?=?0.320, p?=?0.004). Multiple regression analyses indicated that this combination of predictors significantly predicted (F(3, 74)?=?5.043, p?=?0.003) Total FMS? score outcomes and accounted for 17% of the total variance (R2?=?0.170). In addition, logistic regression analyses indicated that estimated 1RM-Squatmax also significantly predicted (χ2?=?6.662, df?=?1, p?=?0.010) FMS? group membership (≤14 or ≥15). Conclusion. These results suggest that the health and fitness measures of obesity (BMI), bilateral lower extremity strength (estimated 1RM-Squatmax), and core muscular endurance (%Plankmax) are significantly associated with functional movement patterns among firefighter recruits. Consequently, injury prevention programs implemented among firefighter recruits should target these aspects of health and fitness.  相似文献   
103.
Meckel–Gruber syndrome is a rare autosomal recessive disorder often resulting in neonatal death within a few hours of life. The condition is usually diagnosed ultrasonographically in the second trimester and earlier diagnosis has been mainly confined to high recurrence risk pregnancies. We describe the earliest non-invasive diagnosis of this condition at 12+2 weeks' gestation in a patient with no previous history using transabdominal ultrasound. Pregnancy termination was declined. Subsequent development of anhydramnios in the mid-trimester resulted in poor fetal visualization. We propose that first-trimester diagnosis of this condition is not only possible but preferable, as normal liquor volume facilitates visualization of fetal anatomy.  相似文献   
104.
试图提出了一种以环境损失作为评价污染源布局判据的观点,给出了大气环境损失系数的计算方法及污染源合理布局优化计算模型,并结合实例作了进一步的分析。  相似文献   
105.
Darwin predicted that scramble competition for access to reproductive females would result in sexual dimorphism of locomotory structures, but direct evidence for this is extremely rare. I examined the relationship between variation in tailfin size and mating success in a field and laboratory study of red-spotted newts, Notophthalmus viridescens. Over three breeding seasons, male tailfin size was positively correlated with variation in male amplexus frequency, and indirectly correlated with male insemination frequency. In a laboratory study, I confirmed that males' ability to capture females is affected by variation in tailfin size. This is the first study to show that naturally occurring variation in male locomotory structures affects male mating success. It corroborates the prediction that scramble competition leads to sexual selection on locomotory structures and, potentially, to dimorphism in these structures. Received: 16 April 1999 / Received in revised form: 16 May 1999 / Accepted: 12 June 1999  相似文献   
106.
● Environmental parameters affected functional bacteria and network associations. ● The structure and interactions of AS networks changed greatly within tanks. ● Anoxic co-occurrence network was more unstable and easily influenced. ● Composition of functional bacteria had a seasonal succession pattern. Tetrasphaera was the major PAO in spring and winter leading a better P removal. Understanding the structures and dynamics of bacterial communities in activated sludge (AS) in full-scale wastewater treatment plants (WWTPs) is of both engineering and ecological significance. Previous investigations have mainly focused on the AS communities of WWTP aeration tanks, and the differences and interactions between the communities in anaerobic and anoxic tanks of the AS system remain poorly understood. Here, we investigated the structures of bacterial communities and their inter-connections in three tanks (anaerobic, anoxic, and aerobic) and influent from a full-scale WWTP with conventional anaerobic/anoxic/aerobic (A/A/O) process over a year to explore their functionality and network differentiation. High-throughput sequencing showed that community compositions did not differ appreciably between the different tanks, likely due to the continuous sludge community interchange between tanks. However, network analysis showed significant differences in inter-species relationships, OTU topological roles, and keystone populations in the different AS communities. Moreover, the anoxic network is expected to be more unstable and easily affected by environmental disturbance. Tank-associated environmental factors, including dissolved oxygen, pH, and nutrients, were found to affect the relative abundance of functional genera (i.e., AOB, NOB, PAOs, and denitrifiers), suggesting that these groups were more susceptible to environmental variables than other bacteria. Therefore, this work could assist in improving our understanding of tank-associated microbial ecology, particularly the response of functional bacteria to seasonal variations in WWTPs employing A/A/O process.  相似文献   
107.
108.
The long-term impact of fulvic acid (FA) on partial nitritation (PN) system was initially examined in this study. The obtained results revealed that the FA lower than 50 mg/L had negligible effect on the nitrite accumulation rate (NAR nearly 100%) and ammonium removal rate (ARR 56.85%), while FA over 50 mg/L decreased ARR from 56.85% to 0.7%. Sludge characteristics analysis found that appropriate FA (<50 mg/L) exposure promoted the settling performance and granulation of PN sludge by removing Bacteroidetes and accumulating Chloroflexi. The analysis of metagenomics suggested that the presence of limited FA (0-50 mg/L) stimulated the generation of NADH, which favors the denitrification and nitrite reduction. The negative impact of FA on the PN system could be divided into two stages. Initially, limited FA (50-120 mg/L) was decomposed by Anaerolineae to stimulate the growth and propagation of heterotrophic bacteria (Thauera). Increasing heterotrophs competed with AOB (Nitrosomonas) for dissolved oxygen, causing AOB to be eliminated and ARR to declined. Subsequently, when FA dosage was over 120 mg/L, Anaerolineae were inhibited and heterotrophic bacteria reduced, resulting in the abundance of AOB recovered. Nevertheless, the ammonium transformation pathway was suppressed because genes amoABC and hao were obviously reduced, leading to the deterioration of reactor performance. Overall, these results provide theoretical guidance for the practical application of PN for the treatment of FA-containing sewage.  相似文献   
109.
In global climate change politics, China and India have worked closely with each other, representing two big emitters from the developing world. This article reviews Sino-Indian cooperation during four UN climate change negotiations from 2009 to 2012. Their collaboration echoed the perception of neorealism in international relations (IR) studies that states will seek “external balancing” for maximizing national “relative gains”. China and India are expected to continue their cooperation on climate change issues when sharing the same structural position as big economies and big emitters, the same pressure in carbon emission reductions, and the same goal of improving living standards for their citizens. Encountering the devastating impacts of climate change and the deadlock in responsibility division in current global climate change governance, this work seeks to shed light on the evolving multilateral governance environment and its complex implications for Sino-Indian relations from an IR perspective.  相似文献   
110.
An Erratum has been published for this article in Prenatal Diagnosis 23(9) 2003, 771 Antenatal detection of an isolated abdominal cyst was found to be a pancreatoblastoma in a female fetus with Beckwith–Wiedemann syndrome. Prenatal and post-natal features and management of this very rare tumour are discussed. Molecular investigation disclosed a mosaic paternal 11p15 uniparental disomy in the tumoral cells. The prognosis of a congenital pancreatoblastoma is good if complete surgical excision is achieved. However, the association with Beckwith–Wiedemann syndrome requires a prolonged follow-up because of the increased risk of developing malignant tumours. Copyright © 2003 John Wiley & Sons, Ltd.  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