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201.
In insects, the last male to mate with a female often gains access to a disproportionate number of subsequent fertilizations.
This study examined last-male sperm precedence patterns in doubly and triply mated Tribolium castaneum females. Sperm storage processes were investigated by measuring the quantity of sperm stored within the female spermatheca
following single, double, and triple matings. Both doubly mated and triply mated females exhibited high last-male sperm precedence
for progeny produced during the first 48 h following the last mating, with females in both groups exhibiting parallel declines
in sperm precedence 1 and 2 weeks later. The number of sperm stored by females increased by 33% between singly mated and doubly
mated females, indicating that the spermatheca is filled to only two-thirds capacity following insemination by the first male.
Based on the proportion of stored sperm from first and second matings, we tested predictions about sperm precedence values
based on models of random sperm mixing. High initial last-male sperm precedence strongly supports stratification of last-male
sperm. By 1–2 weeks after double matings, sperm precedence declined to levels indistinguishable from values expected under
random mixing. These results provide insight into mechanisms of sperm storage and utilization in this species.
Received: 20 August 1997 / Accepted after revision: 24 May 1998 相似文献
202.
Nitrosomonas europaea, a model ammonia oxidizing bacterium, was exposed to a wide variety of aromatic hydrocarbons in 3 h batch assays. The expression of NE1545, a phenol sentinel gene involved in fatty acid metabolism, was monitored via quantitative real-time polymerase chain reaction (qRT-PCR) and a Coulter Counter technique was used to monitor changes in cell volume. Decreases in cell volume and NE1545 gene expression correlated strongly with exposure to aromatic hydrocarbons that possessed a single polar group substitution (e.g. phenol and aniline). Aromatic hydrocarbons that contain no polar group substitutions (e.g. toluene) or multiple polar group substitutions (e.g. p-hydroquinone) caused negligible changes in NE1545 expression and cell volume. The oxidation of aromatic hydrocarbons by N. europaea from configurations without a single polar group to one with two polar groups (e.g. p-cresol oxidized to 4-hydroxybenzyl alcohol) and from configurations with no polar groups to one with a single polar group (e.g. ethylbenzene oxidized to 4-ethylphenol) greatly influenced NE1545 gene expression and observed changes in cell volume. Nitrification inhibition in N. europaea by the aromatic hydrocarbons was found to be completely reversible; however, the decreases in cell volume were not reversible suggesting a physical change in cell membrane composition. Ammonia monooxygenase blocking studies showed that the chemical exposure that was responsible for the cell volume decrease and up-regulation in gene expression and not the observed inhibition. N. europaea is the first bacterium shown to experience significant changes in cell volume when exposed to μM concentrations of aromatic hydrocarbons, three orders of magnitude lower than previous studies with other bacteria. 相似文献
203.
Chen D Liu ZL Banwart W 《Environmental science and pollution research international》2011,18(6):908-917
The potential RDX contamination of food chain from polluted soil is a significant concern in regards to both human health
and environment. Using a hydroponic system and selected soils spiked with RDX, this study disclosed that four crop plant species
maize (Zea mays), sorghum (Sorghum sudanese), wheat (Triticum aestivum), and soybean (Glycine max) were capable of RDX uptake with more in aerial parts than roots. The accumulation of RDX in the plant tissue is concentration-dependent
up to 21 mg RDX/L solution or 100 mg RDX/kg soil but not proportionally at higher RDX levels from 220 to 903 mg/kg soil. While
wheat plant tissue harbored the highest RDX concentration of 2,800 μg per gram dry biomass, maize was able to remove a maximum
of 3,267 μg RDX from soil per pot by five 4-week plants at 100 mg/kg of soil. Although RDX is toxic to plants, maize, sorghum,
and wheat showed reasonable growth in the presence of the chemical, whereas soybeans were more sensitive to RDX. Results of
this study facilitate assessment of the potential invasion of food chain by RDX-contaminated soils. 相似文献
204.
205.
Dusica J. Pesic Milan DJ. Blagojevic Nenad V. Zivkovic 《Environmental science and pollution research international》2014,21(2):1270-1284
Air quality in urban areas attracts great attention due to increasing pollutant emissions and their negative effects on human health and environment. Numerous studies, such as those by Mouilleau and Champassith (J Loss Prevent Proc 22(3): 316–323, 2009), Xie et al. (J Hydrodyn 21(1): 108–117, 2009), and Yassin (Environ Sci Pollut Res 20(6): 3975–3988, 2013) focus on the air pollutant dispersion with no buoyancy effect or weak buoyancy effect. A few studies, such as those by Hu et al. (J Hazard Mater 166(1): 394–406, 2009; J Hazard Mater 192(3): 940–948, 2011; J Civ Eng Manag (2013)) focus on the fire-induced dispersion of pollutants with heat buoyancy release rate in the range from 0.5 to 20 MW. However, the air pollution source might very often be concentrated and intensive, as a consequence of the hazardous materials fire. Namely, transportation of fuel through urban areas occurs regularly, because it is often impossible to find alternative supply routes. It is accompanied with the risk of fire accident occurrences. Accident prevention strategies require analysis of the worst scenarios in which fire products jeopardize the exposed population and environment. The aim of this article is to analyze the impact of wind flow on air pollution and human vulnerability to fire products in a street canyon. For simulation of the gasoline tanker truck fire as a result of a multivehicle accident, computational fluid dynamics large eddy simulation method has been used. Numerical results show that the fire products flow vertically upward, without touching the walls of the buildings in the absence of wind. However, when the wind velocity reaches the critical value, the products touch the walls of the buildings on both sides of the street canyon. The concentrations of carbon monoxide and soot decrease, whereas carbon dioxide concentration increases with the rise of height above the street canyon ground level. The longitudinal concentration of the pollutants inside the street increases with the rise of the wind velocity at the roof level of the street canyon. 相似文献
206.
Lewis P. Goldshore John J. Tozzi 《Journal of the Air & Waste Management Association (1995)》2013,63(3):115-117
This paper examines the history of air pollution control in the State of New Jersey, particularly, how it relates to the development of the state-local governmental relationship, and to the coordination of their respective control efforts. It also describes the methodology for developing local control programs. The information presented in the paper is directed to those individuals who may be able to analogize the experience in New Jersey to situations developing in their own jurisdictions. 相似文献
207.
Lewis H. Rogers 《Journal of the Air & Waste Management Association (1995)》2013,63(8):828-829
The activities and accomplishments of the Air Pollution Control Association during 1974-1975 continued to show growth and expansion, although there was a decline in membership. We have a financial surplus to report in spite of the fact that our publications program was plagued with inflationary price increases in paper, printing and distribution. 相似文献
208.
Reinhold H. Ufrecht Jude T. Sommerfeld H. Clay Lewis 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1348-1352
The purpose of this paper is to provide a helpful tool for the design of adsorption equipment, recognizing in particular the recent, more stringent regulations on air pollution. This work is based on an earlier paper by Hougen and Marshall,1 who developed therein an analytical adsorption model. Under certain assumptions, especially that of linear adsorption equilibrium, it is possible to express the results in the form of convenient usable charts. Although more sophisticated models2 have recently been developed, the numerical effort involved in solving the associated partial differential equations is such that practical application is often questionable. 相似文献
209.
The modulation of worker behavior by the vibration signal during house hunting in swarms of the honeybee, Apis mellifera 总被引:3,自引:3,他引:0
During house hunting, honeybee, Apis melli- fera, workers perform the vibration signal, which may function in a modulatory manner to influence several aspects of nestsite
selection and colony movement. We examined the role of the vibration signal in the house-hunting process of seven honeybee
swarms. The signal was performed by a small proportion of the older bees, and 20% of the vibrating bees also performed waggle
dances for nestsites. Compared to non-vibrating controls, vibrating bees exhibited increased rates of locomotion, were more
likely to move into the interiors of the swarms, and were more likely to fly from the clusters and perform waggle dances.
Recipients responded to the signal with increased locomotion and were more likely than non- vibrated controls to fly from
the swarms. Because vibration signals were intermixed with waggle dances by some vibrators, and because they stimulated flight
in recipients, the signals may have enhanced nestsite scouting and recruitment early in the house-hunting process. All swarms
exhibited increased vibration activity within 0.5–1 h of departure. During these final periods, numerous vibrating bees wove
repeatedly in and out of the clusters while signaling and motion on the swarms increased until it culminated in mass flight.
The peaks of vibration activity observed at the end of the house-hunting process may therefore have activated the entire swarm
for liftoff once a new nestsite had been selected. Thus, the vibration signal may help to integrate the behavior of numerous
groups of workers during nestsite selection and colony relocation.
Received: 17 January 2000 / Received in revised form: 5 April 2000 / Accepted: 3 May 2000 相似文献
210.
Management of microbial contamination in storm runoff from California coastal dairy pastures 总被引:1,自引:0,他引:1
Lewis DJ Atwill ER Lennox MS Pereira MD Miller WA Conrad PA Tate KW 《Journal of environmental quality》2010,39(5):1782-1789
A survey of storm runoff fecal coliform bacteria (FCB) from working farm and ranch pastures is presented in conjunction with a survey of FCB in manure management systems (MMS). The cross-sectional survey of pasture runoff was conducted on 34 pastures on five different dairies over 2 yr under varying conditions of precipitation, slope, manure management, and use of conservation practices such as vegetative filter strips. The MMS cross-sectional survey consisted of samples collected during 1 yr on nine different dairies from six loafing barns, nine primary lagoons, 12 secondary lagoons, and six irrigation sample points. Pasture runoff samples were additionally analyzed for Cryptosporidium sp. and Giardia duodenalis, whereby detectable concentrations occurred sporadically at higher FCB concentrations resulting in poor correlations with FCB. Prevalence of both parasites was lower relative to high-use areas studied simultaneously on these same farms. Application of manure to pastures more than 2 wk in advance of storm-associated runoff was related to a > or =80% reduction in FCB concentration and load compared to applications within 2 wk before a runoff event. For every 10 m of buffer length, a 24% reduction in FCB concentration was documented. A one-half (75%), one (90%), and two (99%) log10 reduction in manure FCB concentration was observed for manure holding times in MMS of approximately 20, 66, and 133 d, respectively. These results suggest that there are several management and conservation practices for working farms that may result in reduced FCB fluxes from agricultural operations. 相似文献