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621.
James O. Luken Steven W. Beiting Scott K. Kareth Robyn L. Kumler Jun H. Liu Craig A. Seither 《Environmental management》1994,18(2):251-255
We tested two cutting regimens (cut/spray and cut/delay spray) and four radiarc-applied herbicides (Garlon + Tordon, Accord,
Accord + Escort, and Krenite) in an Ohio power-line corridor to determine which management combination best eliminated target
species (i.e., trees) and preserved nontarget species (i.e., low shrubs, vines, perennial herbs, and grasses).
When spraying was delayed after cutting, the herbicide with the least impact on nontarget species (Krenite) also was least
efficient at killing target trees. Spraying soon after cutting improved tree-killing efficiency of several herbicides, but
it also increased the negative impact on nontarget species. The herbicide with the most consistent tree-killing ability (Accord
+ Escort) had the most impact on nontarget species.
Because none of the herbicide/cutting treatments performed ideally, resource managers must decide the acceptable impact on
nontarget species when considering herbicide use. Future success of herbicides as part of an integrated succession management
approach requires more selective application methods and formulations so that target effects can be maximized and nontarget
effects can be minimized. 相似文献
622.
Frederick Steiner Scott Pieart Edward Cook Jacqueline Rich Virginia Coltman 《Environmental management》1994,18(2):183-201
The protection of wetlands and riparian areas has emerged as an important environmental planning issue. In the United States,
several federal and state laws have been enacted to protect wetlands and riparian areas. Specifically, the federal Clean Water
Act includes protection requirements in Sections 301 and 303 for state water quality standards, Section 401 for state certification
of federal actions (projects, permits, and licenses), and Section 404 for dredge and fill permits. The Section 401 water quality
state certification element has been called the “sleeping giant” of wetlands protection because it empowers state officials
to veto or condition federally permitted or licensed activities that do not comply with state water quality standards. State
officials have used this power infrequently. The purpose of this research was to analyze the effectiveness of state wetland
and riparian programs. Contacts were established with officials in each state and in the national and regional offices of
key federal agencies. Based on interviews and on a review of federal and state laws, state program effectiveness was analyzed.
From this analysis, several problems and opportunities facing state wetland protection efforts are presented. 相似文献
623.
R. Scott. Beasley Aifredo B. Granillo 《Journal of the American Water Resources Association》1988,24(2):361-366
ABSTRACT: Sediment losses and water yields were measured for five years on nine forested watersheds in the Gulf Coastal Plain of Arkansas. After one year of pretreatment measurements, three watersheds were clearcut and mechanically site prepared, three were selectively harvested, and three control watersheds were left undisturbed. Sediment losses and water yields were similar for the selectively harvested and cohtrol watersheds during all four post-treatment years. However, clearcutting with mechanical site preparation significantly increased sediment losses and water yields above levels measured on other watersheds. Increased sediment losses persisted for two years, while water yields increased for one year. Although sediment losses from clear-cutting were greater than for other treatments, actual losses averaged only 264 kg/ha and 63 kg/ha for the first and second post-treatment years, respectively. The relatively low sediment losses are attributed to the flat terrain and the relatively low flow discharge rates that typify these sites. 相似文献
624.
The challenge of pursuing sustainability in agriculture is often viewed as mainly or wholly technical in nature, requiring the reform of farming methods and the development and adoption of alternative technologies. Likewise, the purpose of sustainability is frequently cast in utilitarian terms, as a means of protecting a valuable resource (i.e., soil) and of satisfying market demands for healthy, tasty food. Paul B. Thompson has argued that the embrace of these views by many in the consumer/environmental movement enables easy co-optation by agribusiness. It also reflects a critical weakness in this movement: a lack of commitment to philosophical principles that depart from the utilitarian premises of the industrial model of agriculture. This paper draws on the writings of Thomas Berry and Liberty Hyde Bailey to identify the philosophical principles of what we call planetary agrarianism. From the perspective of planetary agrarianism, the pursuit of sustainability is a broad and challenging moral, educational, and political task. Berry helps us see that it is fundamentally a project of worldview transition, which requires a new cultural narrative that must rival, in form and appeal, the mythic power of the utilitarian industrial vision. Liberty Hyde Bailey, author of The Holy Earth (1915) and a leader in the land-grant education and nature-study movements, took up the project of worldview transition in his life work. While in some ways dated and flawed, Bailey’s writings are a valuable source of guidance for developing and pursuing a viable philosophy of agriculture for the 21st century. 相似文献
625.
An extensive study on Se accumulation in a population of Anadara trapezia from a marine lake is reported. The effects of organism mass, gender, reproductive cycle, and season on Se accumulation and tissue distribution were investigated. Analyses showed that gender and reproductive cycle had no significant effect on Se accumulation. A. trapezia showed a strong positive correlation between Se burden and tissue mass. Constant Se concentrations were observed within individual populations but varied spatially with sediment Se concentrations. Se concentrations in tissues decreased from gills > gonad/intestine > mantle > muscle > foot, which remained constant over 12 months, however, significantly lower concentrations were observed in the summer compared to winter. A. trapezia is a good biomonitor for Se, as gender and size do not effect concentration, however, season of collection must be reported if changes in Se bioavailability are to be identified in short term studies, or during intersite comparisons. 相似文献
626.
Leclaire S White J Arnoux E Faivre B Vetter N Hatch SA Danchin E 《Die Naturwissenschaften》2011,98(9):773-782
Carotenoid pigments are important for immunity and as antioxidants, and carotenoid-based colors are believed to provide honest
signals of individual quality. Other colorless but more efficient antioxidants such as vitamins A and E may protect carotenoids
from bleaching. Carotenoid-based colors have thus recently been suggested to reflect the concentration of such colorless antioxidants,
but this has rarely been tested. Furthermore, although evidence is accruing for multiple genetic criteria for mate choice,
carotenoid-based colors have rarely been shown to reflect both phenotypic and genetic quality. In this study, we investigated
whether gape, tongue, eye-ring, and bill coloration of chick-rearing black-legged kittiwakes Rissa tridactyla reflected circulating levels of carotenoids and vitamins A and E. We further investigated whether integument coloration reflected
phenotypic (body condition and fledging success) and genetic quality (heterozygosity). We found that the coloration of fleshy
integuments was correlated with carotenoid and vitamin A levels and fledging success but only in males. Furthermore, the coloration
of tongue and eye-ring was correlated with heterozygosity in both males and females. Integument colors might therefore be
reliable signals of individual quality used by birds to adjust their parental care during the chick-rearing period. 相似文献
627.
628.
Previous research has debated whether the collective climates, produced through cluster analysis of psychological climate perceptions, are representative of meaningful organizational collectives or simply statistical artifacts. In this study we examined the extent to which collective climates are comprised of individuals with similar interpretive schemata such as work values and need strength or consist of individuals who share work group or interaction group membership. Measures of psychological climate, work values, need strength, and employee interaction patterns were collected from the management and administrative staff of a manufacturing organization. Results supported the symbolic interactionist perspective to the formation of collective climates. We found clear evidence that collective climates are related to employee interaction groups. Employee interaction based on sensemaking and information seeking activities was most strongly related to shared climate perceptions. There was also some evidence that individuals with similar levels of need strength share collective climate membership. Implications of these results on the debate over the use of collective climates are discussed. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
629.
Critical Success Factors for Behavior-Based Safety: A Study of Twenty Industry-wide Applications 总被引:2,自引:0,他引:2
One-on-one interviews and focus-group meetings were held at 20 organizations that had implemented a behavior-based safety (BBS) process in order to find reasons for program success/failures. A total of 31 focus groups gave 629 answers to six different questions. A content analysis of these responses uncovered critical information for understanding what employees are looking for in a BBS program. A perception survey administered to individual employees (n = 701) at these organizations measured a variety of variables identified in prior research to influence success in safety efforts. The survey data showed five variables to be significantly predictive of employee involvement in a BBS process: 1) perceptions that BBS training was effective; 2) trust in management abilities; 3) accountability for BBS through performance appraisals; 4) whether or not one had received education in BBS; and 5) tenure with the organization. Also, employees in organizations mandating employee participation in a BBS process (n=8 companies) reported significantly higher levels of: (a) involvement; (b) trust in management; (c) trust in coworkers; and (d) satisfaction with BBS training than did employees whose process was completely voluntary (n = 12 companies). In addition, employees in mandatory processes reported significantly greater frequency of giving and receiving positive behavior-based feedback. 相似文献
630.
Findings in multiattribute decision research were used as a basis for predicting the effects of help-wanted advertisement characteristics on vacancy attractiveness. In the first experiment, undergraduate students were presented with entry-level service job advertisements differing in attribute set size, attribute relevance, and pay ambiguity. Results revealed strong evidence for a set-size effect, with ads containing more (relevant or irrelevant) attributes increasing the attractiveness of the vacancies being advertised. Pay ambiguity decreased the attractiveness of vacancies with ads containing a small set of attributes. A second experiment presented students with the same advertisements, except that the small-set ads were physically enlarged to equal the size of the large-set ads. Results replicated the (large) set-size effect only for relevant-attribute ads. Also, pay ambiguity increased the attractiveness of vacancies promoted by ads containing a larger amount of relevant attributes. We conclude that merely adding relevant attribute information to help-wanted advertisements can lead to the inference that the jobs promoted in the ads are more attractive. Moreover, we tentatively suggest that pay ambiguity can lead to pessimistic inferences about pay for ads containing less information, and optimistic inferences about pay for ads containing more information. © 1998 John Wiley & Sons, Ltd. 相似文献