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The forest succession model FORDYN is developed based on TREEDEV model. TREEDEV is a process-based tree growth model, that calculates tree growth based on carbon and nitrogen balance, and is calculated using on the photo-production of leaves, respiration, nitrogen content of all organisms and that in soil, and other losses due to respiration, litter and renewal of stems, branches, leaves and roots. In the FORDYN model succession is divided into three phases called early, middle and late succession, and the transition between these three succession phases is distinguished by a difference in leaf area index. As a verification of the model we used the characteristics and available data of a monsoon evergreen broad-leaved forest in Dinghushan Biosphere Reserve (DHS-BR). The model was validated with natural forest data. In addition, a sensitivity analysis was performed in which 30 independent variables were varied and analyzed in connection with their influence on 16 dependent variables describing forest conditions. The simulation results describe the changes in total biomass, carbon and nitrogen change in plant–litter–soil system of an undisturbed monsoon evergreen broad-leaved forest during succession. We compared these findings with simulation in which different logging management strategies were used. The results show that having a longer logging cycle, delaying the first logging time and a smaller logging fraction the scenario can contribute to a sustainable forest development, while still having a positive economic yield. 相似文献
954.
Michael J. L. Magrath Peter Santema Karen M. Bouwman Dušan M. Brinkhuizen Simon C. Griffith Naomi E. Langmore 《Behavioral ecology and sociobiology》2009,63(5):661-672
Reproductive success within populations often varies with the timing of breeding, typically declining over the season. This
variation is usually attributed to seasonal changes in resource availability and/or differences in the quality or experience
of breeders. In colonial species, the timing of breeding may be of particular importance because the costs and benefits of
colonial breeding are likely to vary over the season and also with colony size. In this study, we examine the relationship
between timing of breeding and reproductive performance (clutch size and nest success) both within and between variable sized
colonies (n = 18) of fairy martins, Petrochelidon ariel. In four of these colonies, we also experimentally delayed laying in selected nests to disentangle the effects of laying
date and individual quality/experience on reproductive success. Within colonies, later laying birds produced smaller clutches,
but only in larger colonies. The general seasonal decline in nest success was also more pronounced in larger colonies. Late
laying birds were generally smaller than earlier laying birds, but morphological differences were also related to colony size,
suggesting optimal colony size also varies with phenotype. Experimentally delayed clutches were larger than concurrently produced
non-delayed clutches, but only in larger colonies. Similarly, delayed clutches were more likely to produce fledglings, particularly
later in the season and in larger colonies. We suggest that the reduced performance of late breeding pairs in larger colonies
resulted primarily from inexperienced/low quality birds preferring to settle in larger colonies, possibly exacerbated by an
increase in the costs of coloniality (e.g., resource depletion and ectoparasite infestations) with date and colony size. These
findings highlight the importance of phenotype-related differences in settlement decisions and reproductive performance to
an improved understanding of colonial breeding and variation in colony size. 相似文献
955.
Soil fertility is conventionally evaluated by soil properties such as C, N, and P contents. Evaluation of soil fertility is
now becoming a routine work for soil management and crop production. However, laboratory-analysis based determination of soil
properties is time and cost consuming, which is not suitable for precision agriculture. Here, infrared spectroscopy (IR) appears
as an alternative and fast technique to measure soil fertility. The IR transmission method is generally used in soil qualitative
analysis, while the IR reflectance can be used in soil quantitative analysis, and most of soil-related research is focused
on reflectance spectroscopy. Infrared reflectance spectra, including diffuse reflectance spectra and total attenuated reflectance
spectra, are involved in soil quantitative analysis. We observe an excellent performance of predicting soil C and N contents
using IR spectra. Moreover, in most of cases the predictions of the contents of soil P, K, Ca, Mg, S, and some other microelements
are satisfactory. Soil water, soil clays, and soil microbes can also be characterized and evaluated using IR spectroscopy.
In recent years, a new method named infrared photoacoustic spectra was applied in soil analysis. Infrared-photoacoustic spectra
is indeed more convenient for sample pretreatment and spectra recording, and the recorded soil spectra contain more useful
information versus conventional reflectance spectroscopy. Though currently the application of infrared photoacoustic spectroscopy
in soil analysis is limited, it appears promising to measure soil fertility. The application of infrared spectroscopy in soil
fertility is largely dependent on spectra pretreatment and multivariate calibration due to strong interferences in the spectra.
Partial least square (PLS) and artificial neural network (ANN) are two widely used mathematical tools in the prediction of
soil properties, and more mathematical tools combined models will benefit the prediction performance. To make full use of
soil infrared spectra, soil spectra library construction is needed in future, and a standard procedure should be first decided
in the construction. Based on soil infrared spectra library soil fertility can be fast evaluated combining suitable mathematical
model, which will play an important role in the sustainable agriculture. 相似文献
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957.
Lianfeng Du Jiaojiao Zhao Farhat Abbas Wenke Liu 《Environmental Chemistry Letters》2013,11(4):385-390
This report shows a higher soil quality under medicinal plants versus food-crop plants. Long-term continuous cultivation of food crops induces changes of soil properties that can lead to fertility loss and, in turn, decline of food productivity. Effect of cropping on soil changes has been studied mainly for food crops and vegetables worldwide, whereas soil changes in herbal fields are scarcely known. Therefore, we compared here soil nutrients and soil chemical properties of herbal fields, cultivated with Chinese medicinal plants, and food-crop fields. Fields are located at the famous traditional planting base of Chinese medicinal plants in Anguo, China. The results showed that in herbal fields, soil nitrate, available P, soil organic matter (SOM), and electrical conductivity decreased with soil depth, whereas soil pH and soil water content increased with depth. In herbal fields, soil nitrate, available P contents, and soil electrical conductivity were higher than those of food-crop fields at various soil layers. SOM and soil water content were similar in herbal and food-crop fields. Soil pH of herbal fields at 0–20 cm was lower than those of food-crop fields. Findings show overall that soil nutrient accumulation and changes under medicinal plants are higher than food-crop fields. 相似文献
958.
目前动脉粥样硬化在全世界以惊人的速度增长,成为21世纪公共健康的严重挑战。持久性有机污染物(persistent organic pollutants,POPs)具有生物富集性和持久性,可通过各种环境介质对人体健康产生危害。研究表明POPs能够改变基因表达,加速动脉粥样硬化的发生发展,因而POPs被认为是动脉粥样硬化的致病风险因素之一。MicroRNAs(miRNAs)是生物进化过程中高度保守的一组非编码小分子RNA,在转录后水平调节基因的表达。miRNAs的差异表达涉及一系列疾病的生理和病理过程。有证据显示,POPs能够引起生物体内miRNAs的表达紊乱,从而引起基因的差异表达。大量文献报道也显示miRNAs在动脉粥样硬化中起重要作用。因此,POPs可能通过miRNA的潜在调控从而导致动脉粥样硬化的发生发展。 相似文献
959.
利用简并引物PCR(polymerase chain reaction,PCR)方法和cDNA末端快速扩增(rapid amplification of cDNA ends,RACE)技术获得马氏珠母贝Pinctada martensii hsp90基因cDNA序列,全长为2 584 bp。根据所得序列设计定量特异性PCR引物,采用半定量RT-PCR以及实时荧光定量(real-time PCR)PCR检测了马氏珠母贝外套膜、鳃、肝胰腺、闭壳肌、性腺、腹足等组织中hsp90基因的表达水平。同时,利用荧光定量PCR技术检测了芘暴露处理前后马氏珠母贝肝胰腺组织中hsp90基因的表达水平。研究结果表明:马氏珠母贝hsp90基因在不同组织中的表达水平为性腺鳃肝胰腺外套膜腹足闭壳肌,表现出组织差异性。芘胁迫对马氏珠母贝hsp90基因的表达有一定的诱导作用,暴露后第1天和第5天,随染毒浓度的增加,hsp90基因的表达上调,呈现出一定的剂量-效应关系,于染毒后第7天基本恢复。研究结果显示,马氏珠母贝hsp90基因可以作为一种理想的分子生物标记物用于监测海洋环境中芘的污染。 相似文献
960.
Zhiyi LI Pengfei DU Haiwei HUANG Yong Ge Xu LI 《Frontiers of Environmental Science & Engineering》2014,8(6):922-928
Non-point source (NPS) pollution simulation in the high-precipitation coastal areas of China is difficult because varying annual typhoon incidence leads to highly contrasting rainfall patterns in dry years and wet years. An IMPULSE (Integrated Model of Non-point Sources Pollution Processes) based NPS model of the Changtan Reservoir watershed, which is a typical high-precipitation coastal area in China, was established based on the analysis of point and NPS pollution data, a digital elevation model, and data on land-use, soil, meteorology, economy, and agricultural management practice. Pre-processed pre-rain- fall soil moisture levels were introduced during the simulation to model the effects of typhoons on hydrology. Rainfall events were simulated sequentially through the year and the model was calibrated and verified using hydrological and water quality data. Accuracy of the simulated rainfall runoff and water quality in the Changtan watershed was found to be acceptable. The study showed that the NPS modeling system could be applied to the simulation and prediction ofNPS loadings in the Changtan Reservoir watershed. 相似文献