全文获取类型
收费全文 | 136篇 |
免费 | 8篇 |
国内免费 | 35篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 6篇 |
地球物理 | 33篇 |
地质学 | 60篇 |
海洋学 | 47篇 |
天文学 | 4篇 |
综合类 | 23篇 |
自然地理 | 5篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 3篇 |
2013年 | 16篇 |
2012年 | 5篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 3篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 1篇 |
排序方式: 共有179条查询结果,搜索用时 15 毫秒
11.
YOU Feng WANG Wei XU Dongdong ZHU Xiangping NI Jing WU Zhihao XU Yongli WANG Xincheng ZHANG Peijun 《中国海洋湖沼学报》2009,27(2)
The hybrid between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus was produced by artificial insemination of olive flounder eggs with stone flounder Sperm. Sinistral and dextral are two types of hybrid progeny after metamorphosis. Karyotypes of both hybrid flounders are the same as those of the two parental species. Of the 22 loci examined from 12 allozymes,12 confirmed hybridization of the paternal and matemal loci in hybrids and no difference was found in allozyme patterns of sinistral and dextral hybrid fishes. RAPD patterns of these specimens were also studied with 38 primers selected from 104 tested. Among them, the PCR products of 30 primers showed hybridization of the paternal and maternal bands. Genetic variation between hybrids and their parental stocks was analyzed by RAPD using 10 of the above 38 primers. The average heterozygosity and genetic distance were calculated. The results suggested that the filial generation could inherit a little more genetic materials from paternal fish than that from maternal fish. 相似文献
12.
林超是著名的中国当代地理学家,他在长达60多年的地理科学研究和教学生涯中,博学精思,成果累累。本文从地理学理沦、地理学方法论、综合自然地理学、中国地理学史、地理教育、中外地理学交流、治学之道等方面,概括了他的学术思想和学术成就。 相似文献
13.
Fossil leaves resembling Nothofagaceae have been investigated from the Eocene of western Antarctica and a new form genus Nothofagofolia is proposed for these kinds of fossils. Some new specimens belonging to this form genus are described. They were collected
from the Fossil Hill locality of Fildes Peninsula, King George Island, South Shetland Islands, western Antarctica. Two new
species, two new combinations and an unnamed species are reported. A number of published Nothofagus leaf fossils from the same locality are discussed and revised. As a result of these studies of Nothofagus leaf morphology, we conclude that (1) Nothofagus probably originated in high latitudes of the Southern Hemisphere during the middle-late Late Cretaceous and diversified,
dispersed gradually to the lower latitudes of the same hemisphere; (2) leaf morphological characters are significant for the
systematics of the family Nothofagaceae, especially at the intrageneric level; and (3) extant species of Nothofagus known from southern temperate areas have more primitive leaf morphological characters and lower leaf ranks than those from
tropical mountains as well as those of the Fagaceae and Betulaceae.
Supported by the Foundation of State Key Laboratory of Palaeobiology & Stratigraphy, Nanjing Institute of Geology and Palaoentology,
Chinese Academy of Sciences (Grant No. 013106), the National Natural Science Foundation of China (Grant No. 30670159) and
the Fund of Innovation Program by Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences 相似文献
14.
Serge H. Zbaz Togouet Thomas Njine Norbert Kemka Moise Nola Samuel Foto Menbohan Walter Koste Claude Boutin Rick Hochberg 《Limnologica》2007,37(4):311-322
Studies on the biodiversity and population dynamics of freshwater planktonic Gastrotricha have been carried out in conjunction with a physical–chemical analysis of the water in the Yaounde Municipal Lake (Cameroon, Central Africa) over a 14 months period (November 1996–December 1997). The results obtained allow to consider the Yaounde Municipal Lake as an eutrophic lake. It harbours eight species of Gastrotricha belonging to four genera (Chaetonotus, Dasydytes, Neogossea and Polymerurus) of the order Chaetonotida. This community was characterized by high abundances of populations, and was dominated by the genus Neogossea and Chaetonotusreaching up to 2000 ind. L−1. Polymerurus was mostly abundant at the almost anoxic bottom layers. The highest abundances were found mostly during the rainy season, when there is an important sedimentation process of organic matter, and were influenced by several different environmental factors such as dissolved oxygen, temperature and pH of the water.
Finally this community which may play an important role in the water bodies, is a potential water quality indicator. 相似文献
15.
《水文科学杂志》2013,58(5)
Abstract Modelling of the rainfall–runoff transformation process and routing of river flows in the Kilombero River basin and its five sub-catchments within the Rufiji River basin in Tanzania was undertaken using three system (black-box) models—a simple linear model, a linear perturbation model and a linear varying gain factor model—in their linear transfer function forms. A lumped conceptual model—the soil moisture accounting and routing model—was also applied to the sub-catchments and the basin. The HEC-HMS model, which is a distributed model, was applied only to the entire Kilombero River basin. River discharge, rainfall and potential evaporation data were used as inputs to the appropriate models and it was observed that sometimes the system models performed better than complex hydrological models, especially in large catchments, illustrating the usefulness of using simple black-box models in datascarce situations. 相似文献
16.
浙江临安板桥奥陶系胡乐组笔石新材料及其意义 总被引:1,自引:1,他引:0
报道在浙江临安板桥奥陶系剖面的胡乐组中发现的较丰富的笔石动物群,包括Pterograptus elegans,Expansograptus sp.1,Tylograptus sp.,Cryptograptus?sp.,Archicli macograptus angulatus,A.caelatus,Procli-macograptus angustatus等主要属种,应属达瑞威尔阶Pterograptus elegans笔石带。这一发现表明,临安板桥一带的胡乐组时代跨度非常局限,底界比浙赣交界"三山地区"的胡乐组之底高2个笔石带,顶界对比则低2个笔石带。其下伏牯牛潭组的顶界与宜昌三峡地区相比,也低了2个笔石带,具明显的穿时现象。 相似文献
17.
为了分析海洋生境刀鲚(Coilia nasus)体内及生长环境菌群结构,作者采用免培养16S r DNA的PCR-DGGE指纹图谱技术,对刀鲚鳃、肠道壁、肠道内容物及水体环境中的菌群结构进行了对比分析。结果表明:变性梯度为35%~55%、浓度为8%的聚丙烯酰胺凝胶,150V 60℃下电泳10 h,DGGE带谱的分离效果较好;刀鲚鳃、肠道壁、肠道内容物及水体样品指纹图谱上分别显示出24、19、14和29条信号强度不同的条带;相同样品重复组细菌结构相似度在80%以上,差异不显著;不同样品之间,刀鲚鳃与海水聚为一支,具有较高的相似度为52%,肠壁与肠内容物相似度为41%。样品菌群主要以未培养菌为主,主要包括变形菌、放线菌和厚壁菌。本文首次成功构建海洋生境刀鲚菌群16S r DNA的PCR-DGGE指纹图谱。 相似文献
18.
Cratosmylus magnificus gen. et sp. nov., type genus and species of the new osmylid subfamily Cratosmylinae, is described from the Lower Cretaceous of the Crato Formation, Brazil. The relationships of this taxon remain uncertain within the Osmylidae, mainly due to the lack of phylogeny of the whole family. Nevertheless, it shares with the Mesozoic subfamily Saucrosmylinae the Rs curved and bent anteriorly distally, even in a more pronounced state, i.e. Rs touching R1 in its distal part. 相似文献
19.
1 INTRODUCTION The first published records of genus Batra-chospermum Roth in China are from Jao (1941), when eleven taxa were reported. Since then, Shi, Hu and Kumano (1993), Shi (1994a, 1994b), Hua and Shi (1996), Xie et al. (1999, 2003), Xie and Shi (2003) have described in more detail the species from China. To date, 23 taxa of Batrachospermum Roth in China have been reported, of which, B. yunnanense, B. nothocladoideum and B. transito-rium are new species of this genus, and are… 相似文献
20.
1 INTRODUCTION Scientific management of aquacultural andnatural populations studies on the early life historyof flatfishes in the aspects of their metamorphosisand benthic settlement accompanying pronouncedtransitions in morphology, behavior and habitatecology have received much attention (Youson,1988). Accumulated data showed that temperatureand substrate played a main role in the recruitmentsuccess of flatfish during their early development(Rijnsdorp et al., 1995, Gibson and Robb, 2000… 相似文献