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701.
G. Bradd Witt Eugene J. Moll Robert J. S. Beeton Peter J. Murray 《Environmental management》1998,22(1):145-152
3 and C4 plant species consumed by animals. Sheep sample vegetation continuously throughout a year, and as their wool grows it integrates
and stores information about their diet. In subtropical and tropical rangelands the majority of grass species are C4. Since sheep prefer to graze, and their wool is an isotopic record of their diet, we now have the potential to develop a
high resolution index to the availability of grass from a sheep's perspective. Isotopic analyses of wool suggest a new direction
for monitoring grazing and for the reconstruction of past vegetation changes, which will make a significant contribution to
traditional rangeland ecology and management. It is recommended that isotopic and other analyses of wool be further developed
for use in rangeland monitoring programs to provide valuable feedback for land managers. 相似文献
702.
鹤壁矿区煤矸石淋滤实验研究 总被引:1,自引:0,他引:1
对鹤壁煤矿区第10矿煤矸石进行连续淋溶试验,模拟煤矸石矿井填充后对地下水环境的影响.测定pH值、电导率、F^-、总硬度、Zn、Mn、Cr^6+、Cd、Cu和Pb等项目,实验结果表明,煤矸石淋出液中F^-和Cr^6+超标,Mn接近标准,pH值偏高,对地下水环境存在一定影响.其他各元素含量甚微,多未检出. 相似文献
703.
The geochemical characteristics of arsenic in the soil of the Western Hunan mining area of P.R. China were systematically
studied. The results show that the strata of Western Hunan are rich in arsenic and that Western Hunan is a geochemically abnormal
region for arsenic. The experimental study on speciation in the strata also indicates that the speciation of arsenic in the
Neoproterozoic-Cambrian strata are mainly easily transferred speciation (exchangeable, carbonate-bound, sulfides-bound), which
are approaching or exceed 60%. Arsenic content in the main soil of Western Hunan is in the range of 8.8–22.8 μg g−1, the mean value is 16.1 μg g−1, which is larger than the arsenic background value of Hunan soil. The distribution of rock with high arsenic content or high
easily transferred arsenic speciation is consistent with the distribution of high arsenic content soil. In the mining region,
part soils and river/brook waters were polluted by mine tailings and mining/smelting waste water. The arsenic content in polluted
paddy soils and river/brook water is 46.26–496.19 μg g−1, 0.3–16.5 mgL−1, respectively. The positive abnormality and pollution of arsenic in the soil and water affects the arsenic content of the
crop and the inhabitants’ health. 相似文献
704.
Sorption of heavy metals to organic matter and mineral soil constituents can hardly be separated experimentally. Here we studied
the retention capacity of organic matter and minerals from soils in a long-term field experiment in which the organic carbon
content had been altered, but the mineral phase had remained constant over time. The sorption of Cu, Cd and Zn showed a non-additive
contribution of soil organic matter and minerals to the sorption capacity of soil. Sorption on organic matter exceeded mineral
sorption from 6 to 13 times. This is the first time that sorption to soil organic matter is quantified in bulk soils. 相似文献
705.
M. S. Pollock R. G. Friesen R. J. Pollock R. C. Kusch D. P. Chivers 《Chemoecology》2005,15(4):205-209
Summary. All animals are vulnerable to predation at some point in their lives and consequently prey organisms often develop effective
risk assessment systems. For many aquatic species predation risk assessment occurs through the use of olfactory cues, including
predator odours and alarm cues from damaged or disturbed conspecifics. When aquatic species encounter conspecific alarm cues
they may respond, or not, based on specific information including cue concentration, health and size of the conspecific donor
and potentially the gender and breeding condition of the donor. Previous laboratory studies have demonstrated that fathead
minnows (Pimephales promelas) fail to respond to the skin extracts of breeding male minnows. The purpose of the current study was to verify these early
laboratory findings in the field as well as to further investigate the effect of female reproductive state and donor gender
on the response of minnows to damage-release alarm cues. Our results indicate that male breeding condition has a significant
effect on how minnows will respond to conspecific cues. Minnows showed avoidance of cues of female minnows and male minnows
not in breeding condition, in comparison to cues of breeding male minnows and cues of male and female swordtails. Neither
the gender of non-breeding minnows nor the reproductive state of female minnows influenced the avoidance of minnows to alarm
cues. 相似文献
706.
天然水中有机污染物的生物降解模拟实验方法 总被引:10,自引:0,他引:10
本文系统地介绍了天然水体中有机污染物生物降解实验室模拟的建立原则、方法和分类,并以有机污染物邻苯二甲酸二甲酯(DMP)和二乙酯(DEP)为例,介绍了生物降解模拟实验过程。 相似文献
707.
Tracer experiments conducted using a flow field established by injecting water into one borehole and withdrawing water from another are often used to establish connections and investigate dispersion in fractured rock. As a result of uncertainty in the uniqueness of existing models used for interpretation, this method has not been widely used to investigate more general transport processes including matrix diffusion or advective solute exchange between mobile and immobile zones of fluid. To explore the utility of the injection-withdrawal method as a general investigative tool and with the intent to resolve the transport processes in a discrete fracture, two tracer experiments were conducted using the injection-withdrawal configuration. The experiments were conducted in a fracture which has a large aperture (>500 microm) and horizontally pervades a dolostone formation. One experiment was conducted in the direction of the hydraulic gradient and the other in the direction opposite to the natural gradient. Two tracers having significantly different values of the free-water diffusion coefficient were used. To interpret the experiments, a hybrid numerical-analytical model was developed which accounts for the arcuate shape of the flow field, advection-dispersion in the fracture, diffusion into the matrix adjacent to the fracture, and the presence of natural flow in the fracture. The model was verified by comparison to a fully analytical solution and to a well-known finite-element model. Interpretation of the tracer experiments showed that when only one tracer, advection-dispersion, and matrix diffusion are considered, non-unique results were obtained. However, by using multiple tracers and by accounting for the presence of natural flow in the fracture, unique interpretations were obtained in which a single value of matrix porosity was estimated from the results of both experiments. The estimate of porosity agrees well with independent measurements of porosity obtained from core samples. This suggests that: (i) the injection-withdrawal method is a viable tool for the investigation of general transport processes provided all relevant experimental conditions are considered and multiple conservative tracers are used; and (ii) for the conditions of the experiments conducted in this study, the dominant mechanism for exchange of solute between the fracture and surrounding medium is matrix diffusion. 相似文献
708.
用两种方法测定已知样,经比较1,10-二氮杂菲分光光度法比原子吸收分光光度法精密度更高、准确度更好. 相似文献
709.
乐昌铅锌尾矿的酸化及重金属溶出的淋溶实验研究 总被引:17,自引:0,他引:17
利用淋溶实验,研究了乐昌铅锌尾矿的酸化及其对重金属溶出的影响。结果表明:高硫和中硫尾矿因含很高的有效硫(分别为20.4%和15.9%),在尾矿的堆放过程中会发生酸化,发生酸化的时间在第51周左右,低硫尾矿(有效硫为7.2%)在短期内不会发生酸化。尾矿发生酸化后,将促进其中盐份的溶解,从而使得Pb、Zn和Cu等重金属的溶出增高。本研究可为铅锌尾矿的环境管理提供科学依据 相似文献
710.