全文获取类型
收费全文 | 18582篇 |
免费 | 180篇 |
国内免费 | 141篇 |
专业分类
安全科学 | 476篇 |
废物处理 | 778篇 |
环保管理 | 2419篇 |
综合类 | 3935篇 |
基础理论 | 4269篇 |
环境理论 | 11篇 |
污染及防治 | 4637篇 |
评价与监测 | 1206篇 |
社会与环境 | 1112篇 |
灾害及防治 | 60篇 |
出版年
2022年 | 141篇 |
2021年 | 147篇 |
2019年 | 131篇 |
2018年 | 258篇 |
2017年 | 255篇 |
2016年 | 390篇 |
2015年 | 291篇 |
2014年 | 432篇 |
2013年 | 1339篇 |
2012年 | 528篇 |
2011年 | 765篇 |
2010年 | 573篇 |
2009年 | 660篇 |
2008年 | 771篇 |
2007年 | 837篇 |
2006年 | 737篇 |
2005年 | 602篇 |
2004年 | 618篇 |
2003年 | 625篇 |
2002年 | 569篇 |
2001年 | 680篇 |
2000年 | 433篇 |
1999年 | 337篇 |
1998年 | 217篇 |
1997年 | 241篇 |
1996年 | 255篇 |
1995年 | 265篇 |
1994年 | 266篇 |
1993年 | 249篇 |
1992年 | 226篇 |
1991年 | 230篇 |
1990年 | 224篇 |
1989年 | 187篇 |
1988年 | 180篇 |
1987年 | 171篇 |
1986年 | 174篇 |
1985年 | 163篇 |
1984年 | 186篇 |
1983年 | 195篇 |
1982年 | 198篇 |
1981年 | 167篇 |
1980年 | 150篇 |
1979年 | 139篇 |
1978年 | 138篇 |
1977年 | 123篇 |
1976年 | 110篇 |
1975年 | 115篇 |
1974年 | 128篇 |
1971年 | 108篇 |
1967年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
511.
Frank A. Ward Thomas P Lynch 《Journal of the American Water Resources Association》1996,32(6):1127-1138
ABSTRACT: This paper presents an integrated optimal control model that optimizes economic performance of reservoir management in watersheds in which there are significant economic and hydrologic interdependencies. The model is solved using the General Algebraic Modeling System (GAMS). Results show that application of this model to New Mexico's Rio Chama basin can increase total system benefits over historical benefits by exploiting complementarities between hydroelectricity production, instream recreation, and downstream lake recreation. 相似文献
512.
Peggy A. Johnson Thomas M. Heil 《Journal of the American Water Resources Association》1996,32(6):1283-1291
ABSTRACT: Bankfull depth and discharge are basic input parameters to stream planform, stream restoration, and highway crossing designs, as well as to the development of hydraulic geometry relationships and the classification of streams. Unfortunately, there are a wide variety of definitions for bankfull that provide a range of values, and the actual selection of bankfull is subjective. In this paper, the relative uncertainty in determining the bankfull depth and discharge is quantified, first by examining the variability in the estimates of bankfull and second by using fuzzy numbers to describe bankfull depth. Fuzzy numbers are used to incorporate uncertainty due to vagueness in the definition of bankfull and subjectivity in the selection of bankfull. Examples are provided that demonstrate the use of a fuzzy bankfull depth in sediment trans. port and in stream classification. Using fuzzy numbers to describe bankfull depth rather than a deterministic value allows the engineer to base designs and decisions on a range of possible values and associated degrees of belief that the bankfull depths take on each value in that range. 相似文献
513.
Car manufacturers must eliminate automotive shredder residues (ASR). Two ways of incineration are of interest: at 850°C in municipal waste incinerators or at higher temperatures, above 1100°C in cement plants. These processes reduce the mass and the volume of waste to be disposed of in landfills and energy recovery might be possible. Regulations govern the emission of gaseous effluents to control environmental risk. To determine gaseous effluents from a pilot sacle or an industrial incineration plant, an artificial ASR was made by mixing three representative organic polymers present in the real ASR, namely polyvinylchloride, polyurethane and rubber. This mixture was incinerated at 850 and 1100°C in laboratory experiments and the analyses of the principal gaseous effluents such as carbon oxides, nitrogen oxides, volatile organic compounds, hydrochloric and hydrocyanic acids and sulphur compounds are presented and discussed. Lastly, in order to simulate artificial ASR behaviour, the composition of the combustion gases at equilibrium was calculated using a Gibbs energy minimisation code. 相似文献
514.
Werner E. G. Müller 《Die Naturwissenschaften》1998,85(1):11-25
Geodia cydonium , which code for proteins. The analyses of their deduced amino acid sequences allowed a molecular biological approach to solve
the problem of monophyly of Metazoa. Molecules of the extracellular matrix/basal lamina, with the integrin receptor, fibronectin,
and galectin as prominent examples, cell-surface receptors (tyrosine kinase receptor), elements of sensory systems (crystallin,
metabotropic glutamate receptor), and homologs/modules of an immune system (immunoglobulin like molecules, scavenger receptor
cysteine-rich, and short consensus repeats, rhesus system) classify the Porifera as true Metazoa. As living fossils, provided
with simple, primordial molecules allowing cell-cell and cell-matrix adhesion as well as processes of signal transduction
as known in a more complex manner from higher Metazoa, they also show peculiarities not known in other metazoan phyla. Tissues
of sponges are rich in telomerase activity, suggesting a high plasticity in the determination of cell lineages. It is concluded
that molecular biological studies with sponges as model will not only help to understand the evolution of Protoctista to Metazoa
but also the complex, hierarchial regulatory network of cells in higher Metazoa. 相似文献
515.
Cardiovascular disease has severe consequences for both individual betterment and organizational health. Yet, organization‐based cardiovascular research remains quite limited. This commentary addresses this void by integrating research dating from the famous Hawthorne experiments with current medical science. It then suggests future organizational research on cardiovascular health and recommends use of specific composite cardiovascular measures to advance our understanding of the organizational implications of cardiovascular disease. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
516.
This study meta‐analyzed the relationships between locus of control (LOC) and a wide range of work outcomes. We categorized these outcomes according to three theoretical perspectives: LOC and well‐being, LOC and motivation, and LOC and behavioral orientation. Hypotheses reflecting these three perspectives were proposed and tested. It was found that internal locus was positively associated with favorable work outcomes, such as positive task and social experiences, and greater job motivation. Our findings are discussed in relation to research on core self‐evaluation and the Big Five personality traits. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
517.
Elvis G. Ngwenya Maud Walsh Caroline A. Metosh‐Dickey Ralph J. Portier 《补救:环境净化治理成本、技术与工艺杂志》2006,16(2):79-90
Biological and physicochemical approaches were utilized in a treatment train for acid mine dis charge (AMD) waters. Anaerobic bioreactors, chemical precipitation reactors, and biopolymer chelation reactors, operated in static, semicontinuous, and continuous flow modes, removed significant quantities of metals and sulfates associated with AMD water. Static tests indicated accept able copper removal via precipitation by generation of hydrogen sulfide in anaerobic reactors. However, low pH affected the biopolymer coating in the chelation reactor, resulting in loss of bed surface. Corrections of AMD to pH > 7 resulted in some metal precipitationprior to biopolymer treatment. A series of static semicontinuous tests at pH 5.0 provided improved metal and sulfate removal. Copper (Cu+) was reduced to trace concentrations, while manganese (Mn+), although reduced, proved to be the most recalcitrant of the metals. © 2006 Wiley Periodicals, Inc. 相似文献
518.
The Muggah Creek estuary in Sydney, Nova Scotia, received liquid and solid wastes from a steel mill and its associated coke ovens for approximately 100 years. This resulted in pollution of soils and sediments with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), heavy metals, and other pollutants, including those in untreated domestic wastewaters. The Canadian federal and Nova Scotia provincial governments organized the Sydney Tar Ponds Agency (STPA) to develop a remediation approach for the Coke Ovens site soils and Sydney Tar Ponds sediments. The STPA developed a remediation approach for the Sydney Tar Ponds sediments, involving solidification/stabilization (S/S) through mixing cement and other materials into the sediments, and then capping them as a waste pile. High‐density polyethylene (HDPE) plastic sheeting vertical barriers are proposed to be used to divert groundwater and surface water from entering into the S/S‐treated sediments and to collect any water and associated pollutants released from the S/S‐treated sediments. The Coke Ovens site soils are proposed to be landfarmed to reduce some of the PAHs and other pollutants and then capped with a layer of soil. This remediation program is estimated to cost on the order of $400 million (CAN). This article presents a review of the significant potential problems with the STPA proposed remediation strategy of the Sydney Tar Ponds sediments and Coke Ovens site soils. © 2006 Wiley Periodicals, Inc. 相似文献
519.
Java(Java也是美国加里福尼亚州Sun Microsystems公司的注册商标)正快速成为一种用于加工制造业和系统集成的计算机编程语言。相对于标准C和C^ 计算机语言而言,Java的多功能性和支持众多计算机操作系统和平台的显著特点,使它能在装备有不同计算机平台和控制系统的机械设备上使用提供了最大的方便性。从而提高了木材产品加工过程的安全性。本文就Java软件系统在木材加工和家具加工过程中的应用以及潜在问题进行探讨。 相似文献
520.
M. R. Theobald U. Dragosits C. J. Place J. U. Smith M. Sozanska L. Brown D. Scholefield A. Del Prado J. Webb P. G. Whitehead A. Angus I. D. Hodge D. Fowler M. A. Sutton 《Water, Air, & Soil Pollution: Focus》2004,4(6):135-142
The distribution and impacts of different nitrogen pollutants are inextricably linked. To understand the problem fully, the interactions between the different pollutants need to be taken into account. This is particularly important when it comes to abatement techniques, since measures to reduce emissions of one nitrogen pollutant can often lead to an increase in another. This project represents a step towards greater understanding of these issues by linking together new and existing nitrogen flux models into a larger framework. The modelling framework has been constructed and some of the nitrogen flows between fields, farms and the atmosphere have been modelled for a UK study area for typical farm management scenarios. 相似文献