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871.
Toshiyuki Fukao MD Akihiro Wakazono Xiang-Qian Song Seiji Yamaguchi Rebecca Zacharias Michael A. Donlan Tadao Orii 《黑龙江环境通报》1995,15(4):363-367
Mitochondrial acetoacetyl-coenzyme A (CoA) thiolase deficiency is an organic aciduria which affects isoleucine and ketone body catabolism. GK16 (the index patient) was affected with this disorder and previous studies had revealed that GK16 was a compound heterozygote with IVS8(+1) gt to tt and A301P mutations. In a subsequent pregnancy, prenatal diagnosis was performed and the fetus's amniocytes were analysed by the polymerase chain reaction (PCR) followed by the heteroduplex detection method on a Mutation Detection Enhancement gel. The fetus was identified as a carrier of the IVS8(+1) mutation. We confirmed the diagnosis by immunoblot analysis of extracted amniocytes and gene analysis with blood filter paper after delivery. This is the first report of prenatal diagnosis of this disorder at the gene level. 相似文献
872.
利用沙门氏菌分解底物形万物地征性荧光的特性,建立了水质沙门氏菌群的”酶-底物“快速检测方法。检测试剂由上医大实验室自行合成,经红外,质谱,核磁共振分析,证明其结构与国报道一致,纯度可达99.99%。MUCAP试验的反应参数;底物最家度为37.5μg/ml,反应最适PH为7.2-7.4。细菌密度和荧光强度随着培养时间增加而增加,敏感度为10^6只/ml,该检测法有较高特异,水中常见的10种细菌未有明 相似文献
873.
运用多时相直接分类法对土地利用进行遥感动态监测的研究 总被引:22,自引:0,他引:22
采用多时相直接分类法对贵州省 (原 )安顺市从1987~1995年间的土地利用变化状况进行了遥感动态监测。与以往方法相比 ,该方法不仅可以直接获得变化类型及其数量 ,而且可以避免分类后比较法所容易出现的逻辑性变化探测错误。对不同分类波段组合的试验表明 ,经过差值、比值处理的前3种波段组合 ,具有较差的分类效果 (总体精度只有30 %~40 % ) ,而那些能较好地保留原始信息的波段组合 ,则具有相对较好的分类效果 (总体精度超过70 % )。另外 ,分类效果还明显地受到所采用的辐射校正方法的影响 ,经过暗组亮组辐射校正的影像要明显比只经过简单辐射校正(直方图法 )的影像具有更好的分类效果 ,总体精度提高了16.6 %。该方法的应用结果表明 ,研究区在8年间经历了一些明显的土地利用变化 ,例如城镇扩展、耕地减少、菜地变迁等。 相似文献
874.
单衬层填埋场渗漏检测ELIM法的正演解析 总被引:1,自引:0,他引:1
建立了填埋场渗漏检测电势映像法(ELIM)模型.将单衬层填埋场看作水平方向为无穷大的3层均匀介质,上层为垃圾层,中间层为人工合成衬层,下层为土壤层.从稳定电流电场的本质出发,将漏洞电流等效为位于电流流入端的负电流源和位于电流流出端的正电流源.基于该模型对填埋场渗漏检测的电势映像法进行了正演解析,并根据模型的基本特征,对3层介质模型的解析结果进行了简化,结果表明该模型中电场在半无穷空间的电势分布与半空间模型中无穷媒质空间中的电势分布规律基本相同. 相似文献
875.
VINCENT DEVICTOR ‡ ROMAIN JULLIARD DENIS COUVET ALEXANDRE LEE† FRÉDÉRIC JIGUET 《Conservation biology》2007,21(3):741-751
Abstract: We studied the community richness and dynamics of birds in landscapes recently affected by urbanization to test the prediction that biotic communities living in degraded landscapes are increasingly composed of generalist species. We analyzed bird communities in 657 plots monitored by the French Breeding Bird Survey from 2001 to 2005, accounting for the probability of species detection and spatial autocorrelation. We used an independent land-cover program to assess urbanization intensity in each FBBS plot, from 1992 to 2002. We found that urbanization induced community homogenization and that populations of specialist species became increasingly unstable with increasing urbanization of the landscape. Our results emphasize that urbanization has a substantial impact on the spatial component of communities and highlight the destabilizing effect of urbanization on communities over time. These results illustrate that urbanization may be a strong driving force in functional community composition and that measuring community homogenization is a powerful tool in the assessment of the effects of landscape changes and thus aides sustainable urban planning. 相似文献
876.
877.
Spatially constrained clustering and upper level set scan hotspot detection in surveillance geoinformatics 总被引:1,自引:0,他引:1
G. P. Patil R. Modarres W. L. Myers P. Patankar 《Environmental and Ecological Statistics》2006,13(4):365-377
We discuss upper level set (ULS) scan as a type of spatially constrained clustering in relation to two ways of imposing the
spatial constraint, retrospectively versus progressively. We show that ULS scan produces the same results both ways; whereas
two popular clustering techniques, single-linkage and K-means, can yield different results when spatial constraints are imposed
retrospectively versus progressively. The ULS scan approach examines spatially connected components of a tessellation as a
threshold is moved from the highest level (value) in the data to the lowest level. When the variable of interest on the tessellation
is a rate of incidence, then a significance test is available based on binomial or Poisson null models and Monte Carlo techniques.
This is a common context for detecting hotspots of diseases in epidemiological work. We also discuss an approach for extending
the univariate methodology to accommodate multivariate contexts.
Received: September 2005 / Revised: February 2006
This material is based upon work supported by (i) the National Science Foundation under Grant No. 0307010, (ii) the United
States Environmental Protection Agency under Grant No. CR-83059301 and (iii) the Pennsylvania Department of Health using Tobacco
Settlement Funds under Grant No. ME 01324. Any opinions, findings, and conclusions or recommendations expressed in this material
are those of the author(s) and do not necessarily reflect the views of the agencies. 相似文献
878.
The maximum likelihood (ML) method for regression analyzes of censored data (below detection limit) for nonlinear models is presented. The proposed ML method has been translated into an equivalent least squares method (ML-LS). A two stage iterative algorithm is proposed to estimate statistical parameters from the derived least squares translation. The developed algorithm is applied to a nonlinear model for prediction of ambient air CO concentration in terms of concentrations of respirable particulate matter (RSPM) and NO2. It has been shown that if censored data are ignored or estimated through simplifications such as (i) censored data are equal to detection limit, (ii) censored data are half of the difference between detection limit and lower limit (e.g., zero or background level) or (iii) censored data are equal to lower limit, this can cause significant bias in estimated parameters. The developed ML-LS method provided better estimates of parameters than any of the simplifications in censored data. 相似文献
879.
Bj?rn?M.?SiemersEmail author Teodora?Ivanova 《Behavioral ecology and sociobiology》2004,56(5):464-471
The 71 species of horseshoe bat (genus Rhinolophus) use echolocation calls with long constant-frequency (CF) components to detect and localize fluttering insects which they seize in aerial captures or glean from foliage. Here we describe ground-gleaning as an additional prey-capture strategy for horseshoe bats. This study presents the first record and experimental evidence for ground-gleaning in the little-studied Blasius horseshoe bat (Rhinolophus blasii). The gleaning bouts in a flight tent included landing, quadrupedal walking and take-off from the ground. The bats emitted echolocation calls continuously during all phases of prey capture. Both spontaneously and in a choice experiment, all six individuals attacked only fluttering insects and never motionless prey. These data suggest that R. blasii performs ground-gleaning largely by relying on the same prey-detection strategy and echolocation behaviour that it and other horseshoe bats use for aerial hawking.We also studied the Mediterranean horseshoe bat (R. euryale) in the flight tent. All four individuals never gleaned prey from the ground, though they appeared to be well able to detect fluttering moths on the ground. It is not known yet whether ground-gleaning plays a role in Mehelys horseshoe bat (R. mehelyi). In a performance test, we measured the ability of these three European species of middle-sized horseshoe bats (R. euryale, R. mehelyi and R. blasii) to take-off from the ground. All were able to take flight even in a confined space; i.e. the willingness to ground-glean in R. blasii is not related to a superior take-off performance. In contrast to ground-gleaning bats of other phylogenetic lineages, R. blasii appears not to be a specialist, but rather shows a remarkable behavioural flexibility in prey-capture strategies and abilities. We suggest that the key innovation of CF echolocation paired with behavioural flexibility in foraging strategies might explain the evolutionary success of Rhinolophus as the second largest genus of bat.Communicated by T. Czeschlik 相似文献
880.
We present a robust sampling methodology to estimate population size using line transect and capture-recapture procedures for aerial surveys. Aerial surveys usually underestimate population density due to animals being missed. A combination of capture-recapture and line transect sampling methods with multiple observers allows violation of the assumption that all animals on the centreline are sighted from the air. We illustrate our method with an example of inanimate objects which shows evidence of failure of the assumption that all objects on the centreline have probability 1 of being detected. A simulation study is implemented to evaluate the performance of three variations of the Lincoln-Petersen estimator: the overall estimator, the stratified estimator, and the general stratified estimator based on the combined likelihood proposed in this paper. The stratified Lincoln-Petersen estimator based on the combined likelihood is found to be generally superior to the other estimators. 相似文献