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31.
跟随叙大铁路尹家岩隧道开挖,对其做了超前预报。当隧道开挖至DK70+551,在其后方出现一大型溶洞,分析了该溶洞的形态特征、岩性、水文地质等情况,提出了换填+护墙、改线和桥梁跨越3个方案,从工期、投资、技术条件、施工难易程度等进行比较,决定采用换填+护墙处理方案进行整治。  相似文献   
32.
《Journal of Natural History》2012,46(41-42):2571-2577
The distribution of predatory soil nematodes (Mononchida) across Europe is well described. However, in Ireland knowledge of mononchids is limited to a single study. The CréBeo project was the first systematic survey of soil biodiversity in the major land-use types across the Republic of Ireland. Nematodes were sampled from 61 locations with an extensive geographical spread including arable, pasture, broadleaf forest, coniferous plantation, rough grazing and peatland sites. This study resulted in 11 first records of mononchid species from Ireland (of which 2 are new records for Britain and Ireland). We discuss the mononchid species found and aspects of their distribution across major land uses.  相似文献   
33.
四平市山门古洞是一个小型裂隙溶洞,原洞内高度不超过1米,洞口高0.3米左右,现已把洞口拓宽并把洞内淤积红土清出大部,拟建一处喀斯特洞穴旅游景点,但因受溶洞基本特征的影响,其开发利用目的尚未实现.因此,山门古洞的开发利用,要在深入研究溶洞形态特征和旅游要素构成的基础上,运用人工造景方法,把山门古洞建设成为一个具有一定观赏价值的旅游景点.  相似文献   
34.
本文介绍了近年发展起来的声发射定量技术。  相似文献   
35.
Based on MC-ICP-MS U-series dating andstable O-isotope analysis results, a 4-5 years resolution monsoon record over the past 1000 years has been established for two stalagmites from Dongge Cave, Guizhou. The high resolution oxygen isotope record serves as a proxy for variations in rainfall of Asian southwest monsoon over the Yunnan-Guizhou Plateau. A close relation of the δ18O record with the A^14C record from tree rings largely reflects impact of centennial-scale solar activity on the monsoon climate changes. The conspicuous decrease in the δ18O value at AD 1720 indicates an abrupt increase in monsoon rainfall, suggesting that an atmospheric-oceanic couple over the tropical Indian Ocean plays an important role in rapid increase of the Northern Hemisphere temperature over the last century.  相似文献   
36.
公路绿化带植物群落特征与土壤理化特性   总被引:1,自引:0,他引:1  
应用野外调查与室内分析方法,分析比较了新建公路绿化带(<1 a)、旧建公路(15 a)绿化带以及研究区内针叶林和两类不同年龄常绿阔叶林的植物群落结构、生物多样性和土壤理化性质。结果表明,新路绿化带植物群落的群落结构最简单,旧路绿化带植物群落次之;与常绿阔叶林群落相比,公路绿化带植物群落的生物多样性较低,尤其是木本植物的物种多样性降低明显。新、旧公路绿化带土壤受扰动严重,土壤容重较大,粗砂粒含量偏高,粘粒含量偏低,新路尤为突出;新、旧公路绿化带植物群落土壤有机质含量和土壤速效养分含量相对其他三种植物群落偏低,新路绿化带相差较大,旧路绿化带相对新路绿化带稍有恢复。  相似文献   
37.
连云港近岸海域底栖动物群落组成及多样性特征   总被引:1,自引:0,他引:1  
在2005年秋对连云港的大型碱厂近海、港区近海和核电站近海的底栖动物进行取样调查,对比研究了不同强干扰环境下底栖动物群落组成及多样性特征, 分析了调查海域环境污染状况.研究表明: 多毛类和软体动物在三个海域中都为优势种类,分别占42.703%,51.352%,56.03%和46.085%,38.145%,32.034%;Shannon-Wiener 指数和均匀度指数的平均值均属核电站海域最大, 分别为3.184和0.868,最小为碱厂海域;丰富度指数的平均值属港区海域最大,为1.416,最小仍为碱厂海域;底栖动物栖息密度值与沉积物中值粒径之间大致呈相反关系;三个海域的28个调查站位中,JC01站底栖动物群落结构受到干扰稍大.  相似文献   
38.
CONSERVATION OF BIODIVERSITIY AND SUSTAINABLE DEVELOPMENT IN CHINA   总被引:1,自引:0,他引:1  
生物多样性是生命系统的基本特征,也是生物有机体及其与环境之间复合而成的生态系统和各种有关生态过程的总和.生物多样性主要包括三个层次基因多样性、物种多样性,生态系统多样性.中国的幅员辽阔,生境复杂,气候多变,历史悠久,拥有丰富的植物、动物和微生物种类及不同的生态系统类型.多年来,我国采取了一系列措施和行动,旨在保护生物多样性,促进国家经济、人类社会和自然生态系统的持续发展.  相似文献   
39.
Many related papers have been published since the first report on the discovery of Nanjing hominid crania by Mu et al.[1]. Mu et al.[1], Xu et al.[2—4], the Tangshan Ar-chaeological Team[5] and Dong[6] have successively stud-ied the Nanjing Homo erectus?symbiotic faunas. Mu et al. and Xu et al. considered that the nature of the fauna in the Tangshan area belongs to the Oriental Realm,and this region was usually occupied by Ailuropoda-Tapirus fauna in the Pleistocene. However, the typica…  相似文献   
40.
Bryozoans are one of the major macrofaunal groups of the high polar regions. Here we present data on the nature of bryozoan assemblages in the Svalbard Archipelago sampled over 6 years between 1997 and 2002. Samples were collected with use of Van Veen grab, dredge and Scuba diving at depths ranging from 0 to 268?m. Among examined material (5026 items) bryozoans were present on one type of abiotic (stones) and 40 types of biotic substrata. The biotic substrata we investigated included algae (12 taxa) and invertebrates (28 taxa: Hydrozoa, Gastropoda, Bivalvia, Polychaeta, Crustacea, Ascidiacea, other Bryozoa). Both a priori ANOSIM (Global R?=?0.512, P?=?0.001) and cluster analyses reveal differences between the assemblages on different types of substrata. Cluster analyses distinguish two distinct groups of substrata. The first (stable) included stones, molluscs and Balanus balanus whilst the second (flexible) consisted of algae, hydrozoans and bryozoans. Bryozoan assemblages which colonized different substrata, varied in terms of species composition and their dominance. Bryozoan species were categorized as generalists, low‐specificity epibiotic species or locally abundant background species. No species were found to be substratum‐specific to any type. Among substrata with the richest bryozoan fauna were stones (156 taxa), Chlamys islandica (68) and Balanus balanus (62). There were clear patterns in the distribution of substrata colonized by bryozoans within the fjord system: those shallow near the mouth were rich whilst those in deeper water were depauperate. We consider environmental gradients such as siltation and processes related to depth to be responsible for such patterns.  相似文献   
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