全文获取类型
收费全文 | 30629篇 |
免费 | 307篇 |
国内免费 | 266篇 |
专业分类
安全科学 | 843篇 |
废物处理 | 1280篇 |
环保管理 | 3995篇 |
综合类 | 4542篇 |
基础理论 | 8279篇 |
环境理论 | 8篇 |
污染及防治 | 8390篇 |
评价与监测 | 2026篇 |
社会与环境 | 1636篇 |
灾害及防治 | 203篇 |
出版年
2022年 | 258篇 |
2021年 | 273篇 |
2020年 | 194篇 |
2019年 | 237篇 |
2018年 | 419篇 |
2017年 | 458篇 |
2016年 | 673篇 |
2015年 | 551篇 |
2014年 | 878篇 |
2013年 | 2536篇 |
2012年 | 1003篇 |
2011年 | 1329篇 |
2010年 | 1096篇 |
2009年 | 1163篇 |
2008年 | 1320篇 |
2007年 | 1435篇 |
2006年 | 1229篇 |
2005年 | 1038篇 |
2004年 | 1055篇 |
2003年 | 999篇 |
2002年 | 992篇 |
2001年 | 1238篇 |
2000年 | 894篇 |
1999年 | 509篇 |
1998年 | 371篇 |
1997年 | 391篇 |
1996年 | 434篇 |
1995年 | 460篇 |
1994年 | 434篇 |
1993年 | 366篇 |
1992年 | 359篇 |
1991年 | 339篇 |
1990年 | 369篇 |
1989年 | 345篇 |
1988年 | 303篇 |
1987年 | 302篇 |
1986年 | 275篇 |
1985年 | 280篇 |
1984年 | 294篇 |
1983年 | 284篇 |
1982年 | 269篇 |
1981年 | 267篇 |
1980年 | 231篇 |
1979年 | 249篇 |
1978年 | 198篇 |
1977年 | 198篇 |
1976年 | 153篇 |
1975年 | 170篇 |
1973年 | 180篇 |
1972年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
251.
A simple method of time series analysis, based upon linear least squares curve fitting, is developed. The method's advantages and disadvantages are discussed, and an example is presented using the Vostok Core methane record. 相似文献
252.
Aston C.Chipanshi 《Ambio-人类环境杂志》2002,31(1):30-34
本文分析了在博茨瓦纳有效执行<蒙特利尔议定书>中遇到的困难;并就在发展中国家执行国际协定问题时如何向决策者提出建议提供了一个总的认识.对臭氧耗损物质(ODSs)的正式和非正式用户进行的问卷调查表明:所散发的有关ODSs的信息,对于用户们选择制冷气体几乎没有什么影响,而且这个信息偏向有利于ODSs的正式用户.因此,ODS使用数量的年统计资料可能估计偏低.困难在于,要在短期内从老技术转向新技术,成本较高.回收废气和处理废旧硬件设备的基础设施缺乏或不足.这些问题的解决需要一个全面的政策,它能满足所有ODSs用户的要求;还需要把经济发展与环境保护结合起来进行考虑. 相似文献
253.
J. Altenburger Th. Dielacher P. Eder H. Ferner M. Fegerl J. Fresner O. Gelinek A. Kogler J. Jantschgi M. Nussbaumer B. Russegger H. Schnitzer K. Schauer B. Sebesta J. Seiler F. Sprenger H. Widenmeyer 《Journal of Cleaner Production》1994,2(3-4)
The paper focuses upon the organization of a federal state-funded pollution prevention project in the Styrian industry. The project includes 13 companies from the textile, pulp and paper, machine building, wood working and printed circuit board manufacturing industries, covering most of the sectors and sizes in the Styrian industry. It started in January 1994 and will last for one year. It will demonstrate the possibilities of pollution prevention and the need for further research work. This project will make use of the methods and tools that were refined in the Austrian Prepare project. As a first step, a systematic balance of all the inputs and outputs of a company is made, after which the weak points and inefficiencies of material and energy use are identified and the options for improvements, both economical and ecological, are defined. Consequently, modifications in products and production lead to a situation with less waste and emissions. The preliminary lessons from these projects are presented: as a rule, the utilities (consumption of process materials and water, cleaning, energy, preparatory and finishing steps) are treated as black boxes and usually represent a considerable optimization potential. In these areas especially there is usually a lack of information and coordination as well as a need for a systematic and comprehensive approach. Leadership in the company and creative consultants are needed for starting lasting successful pollution prevention projects. 相似文献
254.
Bernd P. Maier 《Die Naturwissenschaften》1977,64(2):59-68
The 57-MW high-flux reactor of the Institute Max von Laue-Paul Langevin at Grenoble serves as a central neutron-beam facility for laboratories and research institutes in the three member countries, the United Kingdom, France, and the Federal Republic of Germany. The heavy-water-moderated and -cooled reactor is equipped with hot, thermal, and cold moderators, providing neutrons with high intensity over an unusual wide range of energies (wavelengths) extending from some 0.1 meV (30 Å) up to some 500 meV (0.4 Å). An extensive system of neutron guides with different curvatures permits the transport of neutrons over distances ranging up to 140 m with minimal intensity losses for neutrons in the useful wavelength band. The transmitted beams, in addition, exhibit very low background contamination by fast and epithermal neutrons, and γ-radiation. A large variety of high-resolution neutron spectrometers provide unique opportunities in fields such as nuclear physics, crystallography, solid-state physics, chemistry, metallurgy, and biology. 相似文献
255.
C. K. Jørgensen 《Die Naturwissenschaften》1980,67(4):188-189
256.
Distribution of actinomycetes in oil contaminated ultisols of the Niger Delta (Nigeria) 总被引:1,自引:0,他引:1
J.P.Essien 《环境科学学报》2000,12(3):296-302
The distribution of actinomycetes in oil contaminated sandy loam ultisols of the Niger Delta region of Nigeria was studied to aid in understanding the effect of hydrocarbons on indigenous microbial population in tropical soils. The average total counts of actinomycetes in all the oil samples analysed was 103 cfu/g. Higher counts of actinomycetes were observed during the dry season than during the wet season. The counts of hydrocarbonoclastic actinomycetes correlated positively with the total count of actinomycetes.The actinomycetes were generally restricted to the top soil(0-10 cm soil depth) although a seemingly deeper(down to 40 cm soil depth) distribution was noticed in the dry season. The isolates included oil degrading species of Actinoplanes, Norcadia,Streptomyces and Streptosporangium. Their high oil utilization ability indicates their positive potential and role in the bioremediation of oil-spilled soils. 相似文献
257.
258.
Mendel Z Dunkelblum E Branco M Franco JC Kurosawa S Mori K 《Die Naturwissenschaften》2003,90(7):313-317
The biological activity of the Matsucoccus spp. sex pheromones and diene modified analogs has been tested in forests of Israel and Portugal in order to explore the structure-activity relationship of the pine bast scale pheromone/kairomone system. The response of the adult predatory bugs, Elatophilus hebraicus and E. crassicornis and of the brown lacewing, Hemerobius stigma is more selective than that of the conspecific Matsucoccus males. The removal of the terminal methyl group from the diene terminus of both pheromones 1 and 2 eliminates all kairomonal activity but retains moderate pheromonal activity. Addition of a methyl group to the diene terminus of pheromones 1 and 2 sustains full pheromonal and kairomonal activities of the Elatophilus spp. but eliminates entirely the kairomonal activity of H. stigma. Subtle designed alterations in the structure of the diene group, typical of all Matsucoccus pheromones, change the mode of the kairomonal activity markedly. 相似文献
259.
260.
E. Lamla F. Boschke G. Traving G. Pfotzer H. Wolter W. Walcher H. D. Dahmen H. J. Queisser W. W. Klingbeil K. Beyermann O. Müller R. R. Ernst D. Reinen H. Muth W. Becker G. Wunsch G. I. Distler L. Jaenicke H. G. v. Schnering H. Werner F. Reiff H. Schimassek W. Höll H. K. Vasil W. F. Angermeier W. Ruppel J. C. Eccles G. Spiteller H. Oettel W. Vogell P. Brosche K. J. Hsü H. -U. Schmincke 《Die Naturwissenschaften》1975,62(3):143-143