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   1879篇
  免费   120篇
  国内免费   603篇
安全科学   139篇
废物处理   118篇
环保管理   140篇
综合类   1107篇
基础理论   312篇
污染及防治   555篇
评价与监测   99篇
社会与环境   64篇
灾害及防治   68篇
  2024年   6篇
  2023年   51篇
  2022年   141篇
  2021年   114篇
  2020年   86篇
  2019年   84篇
  2018年   78篇
  2017年   94篇
  2016年   106篇
  2015年   106篇
  2014年   125篇
  2013年   185篇
  2012年   152篇
  2011年   154篇
  2010年   117篇
  2009年   110篇
  2008年   106篇
  2007年   113篇
  2006年   76篇
  2005年   56篇
  2004年   36篇
  2003年   56篇
  2002年   63篇
  2001年   45篇
  2000年   48篇
  1999年   45篇
  1998年   39篇
  1997年   39篇
  1996年   40篇
  1995年   26篇
  1994年   13篇
  1993年   25篇
  1992年   15篇
  1991年   10篇
  1990年   11篇
  1989年   3篇
  1988年   10篇
  1987年   3篇
  1986年   3篇
  1985年   1篇
  1984年   3篇
  1982年   3篇
  1981年   2篇
  1958年   1篇
  1956年   2篇
排序方式: 共有2602条查询结果,搜索用时 265 毫秒
911.
The negative effects of overexposure to ultraviolet (UV) radiation in humans, including sunburn and light-induced cellular injury, are of increasing public concern. 4-Methylbenzylidene camphor (4-MBC), an organic chemical UV filter, is an active ingredient in sunscreen products. To date, little information is available about its neurotoxicity during early vertebrate development. Zebrafish embryos were exposed to various concentrations of 4-MBC in embryo medium for 3 days. In this study, a high concentration of 4-MBC, which is not being expected at the current environmental concentrations in the environment, was used for the purpose of phenotypic screening. Embryos exposed to 15 μM of 4-MBC displayed abnormal axial curvature and exhibited impaired motility. Exposure effects were found to be greatest during the segmentation period, when somite formation and innervation occur. Immunostaining of the muscle and axon markers F59, znp1, and zn5 revealed that 4-MBC exposure leads to a disorganized pattern of slow muscle fibers and axon pathfinding errors during the innervation of both primary and secondary motor neurons. Our results also showed reduction in AChE activity upon 4-MBC exposure both in vivo in the embryos (15 μM) and in vitro in mammalian Neuro-2A cells (0.1 μM), providing a possible mechanism for 4-MBC-induced muscular and neuronal defects. Taken together, our results have shown that 4-MBC is a teratogen and influences muscular and neuronal development, which may result in developmental defects.  相似文献   
912.
In this paper, computational modeling is created for 3 MW wind turbine blade using the software Solidworks, and the computations are carried out using Workbench for the fluid–structure interaction of blades due to both the rated and the extreme wind load. The methods developed are applied to the simulation of the NREL Phase VI wind turbine blades, and validation against published data is presented. Moreover, the static structural analysis for wind turbine rotor is performed using Mechanical APDL. The results show that the maximum values of stress reach 458 MPa and 76.9 MPa due to the rated and extreme wind load, respectively, which are lower than 78.3 MPa, the flexural strength of Swancor 2511-A epoxy resin for blade material.  相似文献   
913.
A novel on-board hydrogen generation concept using Al coil with NaOH was investigated. The reaction rate was successfully controlled by introducing a pumping system for the NaOH solution. The time for the flow to develop fully was mainly dependent on the solution temperature, and the fastest start time recorded was 60 sec at a solution temperature of 70°C. The maximum H2 generation rate was 200 L min–1 with a prototype design of the on-board hydrogen generation system 1/8 times the size of a full-size reactor. The H2 generation process coupled with the solution pumping system was simulated with three-dimensional fluid dynamic software, and the calculated H2 flow and temperature rise of the system were validated with experimental data.  相似文献   
914.
A number of literatures have documented adverse health effects of exposure to fine particulate matter (PM2.5), and secondary sulfate aerosol and black carbon may contribute to health impacts of PM2.5 exposure. We designed an exposure system to generate sulfate and traffic soot particles, and assessed the feasibility of using it for human exposure assessment in a pilot human exposure study. In the designed exposure system, average mass concentrations of generated sulfate and soot particles were 74.19μg/m3 and 11.54μg/m3 in the chamber and did not vary significantly during two-hour human exposure sessions. The size ranges of generated sulfate were largely between 20 to 200 nm, whereas those of generated soot particles were in the size ranges of 50 to 200nm. Following two-hour exposure to generated sulfate and soot particles, we observed significant increases in fractional exhaled NO (FeNO) in young and health subjects. Building on established human exposure system and health response follow-up methods, future full-scale studies focusing on the effects of mixed particulates and individual PM2.5 components would provide data in understanding the underpinning cardio-respiratory outcomes in relation to air pollution mixture exposure.

Implications: Controlled exposure is a useful design to measure the biological responses repeatedly following particulate exposures of target components and set exposure at target levels of health concerns. Our study provides rational and establishes method for future full-scale studies to focus on examining the effects of mixed particulates and individual PM2.5 components.  相似文献   

915.
SMBBR预处理发酵类制药废水   总被引:1,自引:0,他引:1       下载免费PDF全文
采用高活性反硝化菌DNF409作为菌种,以SDC-03型生物载体作为填料,通过特异性移动床生物膜反应器预处理发酵类制药废水。实验结果表明:在反应温度为22~26℃、DO为2~4 mg/L、污泥质量浓度为2 000 mg/L、水力停留时间为16 h的条件下,COD,NH3-N,TN,TP的平均去除率分别为72.45%,27.72%,18.54%,84.58%,BOD5/COD由0.17提高到0.38,废水的可生化性得到提高;出水经后续生化处理达到GB 21903—2008《发酵类制药工业水污染物排放标准》的排放要求。  相似文献   
916.
采用一维土柱装置模拟非水相液体(NAPLs)在我国两种典型土壤(北京潮土与湖南红壤)中的垂向迁移过程,以甲苯为例研究了其在两种土壤中的迁移性能;采用XRD技术测定土壤的矿物组成。实验结果表明,当潮土和红壤孔隙率均为45%时,甲苯在潮土中的迁移速率和最终迁移距离均显著高于在红壤中。甲苯在潮土中的阻滞系数(Rf=18.9)小于在红壤中(Rf=26.5),表明红壤对甲苯的吸附阻滞作用强于潮土。XRD表征结果显示,红壤中粒径小的黏粒含量较高,具有较多的黏土矿物,对甲苯具有更强的吸附阻滞能力,致使甲苯在红壤中垂向迁移速率小,最终迁移距离较短。  相似文献   
917.
Mushrooms are considered as potential bio-remediation agents in soil polluted with heavy metals, while many species which efficiently accumulate them in flesh are edible. Question is if there is any possible culinary use of edible mushrooms with high heavy metal contents? This study aimed to investigate and discuss a fate of cadmium (Cd) in common household-treated fruitbodies of common chanterelle Cantharellus cibarius. The samples of Cantharellus cibarius Fr. were collected from five spatially distanced sites in Poland in 2011–2012. We examined from 267 to 358 fruiting bodies per collection, and in total 1565 fruiting bodies were used. Cadmium in fungal materials from all treatments and processes (mushrooms dried, deep frozen, blanched and pickled) was determined using validated methods by inductively coupled plasma mass spectrometry with dynamic reaction cell. Blanching of fresh chanterelles caused decrease of Cd by around 11 ± 7 to 36 ± 7%, while blanching of deep-frozen mushrooms by around 40 ± 6%. A rate of Cd decrease in chanterelles was similar when the fruiting bodies were blanched for 5 or 15 min and when used was potable or deionized water. Pickling of blanched chanterelles with a diluted vinegar marinade had a pronounced effect on further removal of Cd. Blanched chanterelles when pickled lost an extra 37–71% of Cd. Total leaching rate of Cd from fresh or deep-frozen fruitbodies of chanterelle when blanched and further pickled was between 77 ± 7 and 91 ± 4%. Blanching and pickling highly decreased content of Cd in C. cibarius.  相似文献   
918.
赵毅  韩育宏  张玄  王涵 《化工环保》2017,37(4):383-388
非均相光催化氧化是一种催化剂易于回收利用且研究广泛的高级氧化技术。本文综述了多金属氧酸盐(POMs)非均相光催化降解废水中有机污染物的研究现状。该类非均相光催化剂主要包括负载型POMs(载体主要有半导体氧化物、离子交换树脂和分子筛)、POMs复合膜材料、不溶性盐和多元复合物。讨论了其制备方法、降解效果、反应机理和重复使用性。最后,指出了该领域未来可能的研究方向,为该领域的进一步研究提供参考。  相似文献   
919.
The important criteria in anaerobic digestion is the rate-limiting step which decides the fate of value-added products especially from waste-activated sludge (WAS). Hence, the present study investigated the effect of magnesium (Mg2+) addition on anaerobic digestion of WAS. The lab-scale experiments were conducted at 25 °C with Mg2+ doses ranging from 0.01 to 0.2 mol/L. Maximum total volatile fatty acids (VFAs) production (372.78 mg COD/L) occurred at a Mg2+ dose of 0.2 mol/L, which was about eight times higher than the control tests. Further, Mg2+ addition facilitated sludge dewaterability and phosphorus removal. The mechanism of improved VFAs generation was analyzed from the view of both chemical and biological effects. Chemical effect significantly enhanced the release of calcium and iron in WAS, resulting in the disintegration of WAS, which benefited hydrolysis and acidification processes. Illumina MiSeq sequencing analysis revealed that enrichment of functional bacteria and the increase of bacterial diversity were obtained in the 0.2 mol Mg2+/L experiment, while the influence was negative on the reactor with 0.025 mol/L Mg2+. Meanwhile, methanogens were accordantly inhibited in the experiments with Mg2+ addition.  相似文献   
920.
Electrophoresis release test (ERT) was established by our lab to observe the re-released hemoglobin (Hb) from red blood cells (RBCs) and whole blood. In this study, ERT was performed to study the effects of different plasma components including plasma, serum, albumin, globulin, fibrinogen, glucose, amino acid, vitamin, insulin, hormone, and inorganic ions on re-released Hb from RBC and whole blood samples during ERT. The results showed that plasma, serum, albumin, globulin, compound amino acid, essential amino acid, vitamin C, insulin, hormone, NaCl, KCl, CaCl2, and NaHCO3? decreased re-released RBC Hb; while glucose, vitamin B1, vitamin B2, and vitamin B12 elevated re-released RBC Hb. The differing effects of various plasma components on re-released Hb of RBC may play a significant role in blood conservation.  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