全文获取类型
收费全文 | 12824篇 |
免费 | 1010篇 |
国内免费 | 4276篇 |
专业分类
安全科学 | 820篇 |
废物处理 | 798篇 |
环保管理 | 967篇 |
综合类 | 6900篇 |
基础理论 | 2392篇 |
环境理论 | 6篇 |
污染及防治 | 4756篇 |
评价与监测 | 473篇 |
社会与环境 | 433篇 |
灾害及防治 | 565篇 |
出版年
2024年 | 102篇 |
2023年 | 310篇 |
2022年 | 655篇 |
2021年 | 497篇 |
2020年 | 401篇 |
2019年 | 388篇 |
2018年 | 486篇 |
2017年 | 565篇 |
2016年 | 691篇 |
2015年 | 879篇 |
2014年 | 973篇 |
2013年 | 1272篇 |
2012年 | 1019篇 |
2011年 | 1192篇 |
2010年 | 855篇 |
2009年 | 847篇 |
2008年 | 888篇 |
2007年 | 695篇 |
2006年 | 656篇 |
2005年 | 483篇 |
2004年 | 351篇 |
2003年 | 438篇 |
2002年 | 383篇 |
2001年 | 313篇 |
2000年 | 342篇 |
1999年 | 400篇 |
1998年 | 328篇 |
1997年 | 311篇 |
1996年 | 296篇 |
1995年 | 260篇 |
1994年 | 177篇 |
1993年 | 156篇 |
1992年 | 113篇 |
1991年 | 98篇 |
1990年 | 68篇 |
1989年 | 60篇 |
1988年 | 52篇 |
1987年 | 31篇 |
1986年 | 35篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
631.
You think you are big fish in a small pond? Perceived overqualification,goal orientations,and proactivity at work 下载免费PDF全文
Overqualification denotes situations in which job incumbents have higher qualifications than those required for the job. Drawing on the self‐regulatory perspective, we proposed that employees' perception of overqualification positively affects their proactive behavior through the mechanism of role‐breadth self‐efficacy and that this indirect effect is moderated by employees' goal orientations. We tested our hypotheses through two studies. In Study 1, we found that perceived overqualification had a positive indirect effect on employees' proactive behavior through role‐breadth self‐efficacy using a sample of 323 salespeople with a cross‐lagged panel design. In Study 2, the multi‐wave and multi‐source data from 302 teachers confirmed the indirect effect and indicated that performance goal orientation and learning goal orientation moderated the indirect relationship. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
632.
为有效去除发电厂烟气中产生的NOx,利用介质阻挡放电(DBD)产生低温等离子体并结合催化剂Ag/Al2O3进行烟气脱硝实验,研究了在加入乙烯的条件下,平均负载量、催化温度和装置的布置方式对NOx脱除的影响。结果表明,随着负载的增多,NO脱除率呈现先增大后减小的趋势,5种负载量中最佳为1.76%;随着催化温度的升高,NO脱除率同样呈现先增大后减小的趋势,最佳的催化温度为150℃左右;3种不同布置方式对NO和NOx脱除有明显差别,单独催化剂在NO和NOx的脱除率都比较低;单独介质阻挡放电NO脱除率很高,但是NOx很却很低;而两者结合在NO和NOx都达到了很好的效果。 相似文献
633.
介绍了一种已申请国家专利的铝螺母的加工方法。并就冷挤压时零件的变形、模具机构的设计等作了较为详细的论述。 相似文献
634.
提出用微波加热一二氧化碳活化法再生乙酸乙烯合成用触媒载体废活性炭工艺。采用条件实验法研究了活化时间、二氧化碳流量和微波功率对活性炭碘吸附值,亚甲基蓝吸附值和再生得率的影响,得到微波辐射加热二氧化碳活化再生乙酸乙烯用触媒载体废活性炭的最佳工艺条件为活化时间25min,二氧化碳流量0.2L/min,微波功率700w。在此条件下制得的活性炭碘吸附值为1158.02mg/g、亚甲基蓝吸附值为240mv,/g、得率为74.19%。并对活性炭进行了比表面积的测定和孔结构的分析,活性炭的比表面积为1308.13m^2/g,总孔容为0.76mL/g。 相似文献
635.
The coke-slag mixture discharged from water-air generators not only causes a serious environmental problem, but also is a potential resource. In order to obtain a high economic return, separation of fine binary mixtures in a vibrating fluidized bed with dense media was experimentally investigated. The effects of volume ratio (mono-component volume to dense medium volume or binary mixture volume to dense medium volume), the fluidization velocity and vibration parameters on separation efficiency are discussed. The experimental results show that vibration can prevent the coalescence and growth of bubbles and improve fluidization properties of particles and the stability of bed density. The major factors associated with separating efficiency are discussed. Based on the experiments, the ratio of the volume of particles to bed volume and the vibration conditions are also reported. It was found that the separation efficiency for a fine coke-slag mixture was greater than 70% and close to 80% under optimal conditions. 相似文献
636.
Hongyu Liu Hu Zhang Shan Chen Dongbo Liu Hongmei Xia 《Journal of Polymers and the Environment》2006,14(4):419-426
An extracellular poly (β-hydroxybutyrate) (PHB) depolymerase was purified from a Penicillium sp. DS9701-09a by centrifugation, ultrafiltration, precipitation and gel filtration chromatography. The specific activity of the purified enzyme was 37.9-folds higher than that of the culture supernatant and the recovery yield was 11.8%. The PHB deploymerase molecular mass was 44.8 kDa from analysis of both Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Matrix-assisted laser desorption-time-of-flight (MALDI-TOF) mass spectrometer. The isoelectric point of 6.7 for the enzyme was determined by a two-dimensional electrophoresis. The optimum enzyme activity was observed at a temperature of 50 °C and pH 5.0. The apparent K
m of the enzyme was found to be 1.35 mg/mL. The PHB depolymerase consisted of 16 kinds of normal amino acids. The secondary structure of the enzyme was determined by CD spectrum. α-helix and β-turn were found to be 66% and 34% for the enzyme without ammonium sulphite. Chemical inhibition on the PHB depolymerase activity was examined and EDTA was found to have a significantly inhibitory effect. 相似文献
637.
Peng X Zhang K Tang C Huang Q Yu Y Cui J 《Journal of environmental monitoring : JEM》2011,13(2):446-454
Occurrence, behavior and fate of several groups of antibacterials were investigated in municipal wastewater, sewage sludge, and urban river water in China. Fluoroquinolones (e.g., ciprofloxacin, norfloxacin, and ofloxacin), macrolides (dehydroerythromycin, roxithromycin, and clarithromycin), sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim were ubiquitously detected in the wastewater in China. Fluoroquinolones were generally the most abundant in the raw sewage, with a maximum concentration of up to 6415 ng L(-1) observed for norfloxacin. Sulfonamides and macrolides transported predominantly in the aqueous phase. A median percentage of 67% of sulfonamides and 86% of macrolides remained in the final effluent after treatment in sewage treatment plants. On the contrary, sorption played a significant role in transport of fluoroquinolones and approximately half of the fluoroquinolones finally ended up and persisted in the dewatered sludge. In the urban section of the Pearl River at Guangzhou, sulfonamides, trimethoprim, and macrolides were widely present at median concentrations of 22-735 ng L(-1), whereas fluoroquinolones were only occasionally detected at 2-152 ng L(-1), probably due to their strong tendency of partition to sediment and/or photodegradability. The result of principal components analysis suggests input of non-sewage derived sulfamethazine in the Pearl River. Seasonal variations of the antibacterials distribution in the wastewater are mainly ascribed to different consumption. Dilution effect by precipitation, however, also plays an important role in seasonal distribution of the antibacterials in the Pearl River. 相似文献
638.
油品储运对环境的影响及其防治措施 总被引:5,自引:0,他引:5
油品在储运过程中产生一定的损耗,造成对大气环境污染,从而影响人类健康,着重分析装油、卸油等过程中的损耗,并且给出了常压油罐油品储存、液体石化产品装车挥发损耗量,还提出了科学的油品储存管理,改进储运操作;将拱顶罐改造成内浮顶式油储罐和采用密闭化装车等防治污染措施,以保护环境,提高经济效益。 相似文献
639.
应用D412螯合树脂治理含镍电镀废水的研究 总被引:1,自引:0,他引:1
本文研究了D412螯合树脂对Ni(Ⅱ)离子静态和动态的吸收性能,并且研究了使用D412树脂除去和回收电镀废水中镍的最佳条件。 相似文献
640.
以廉价的铝土矿为原料,辅以适当添加剂,经简单处理,在700℃-800℃的温度下灼烧3h,即可制成能够去除水中高浓度SO^2-4的高效净水剂。将该净水剂加到适量的高浓度SO^2-4水中,处理30min,就能达到国家饮用水标准。 相似文献