全文获取类型
收费全文 | 9308篇 |
免费 | 296篇 |
国内免费 | 859篇 |
出版年
2024年 | 25篇 |
2023年 | 70篇 |
2022年 | 107篇 |
2021年 | 131篇 |
2020年 | 157篇 |
2019年 | 190篇 |
2018年 | 154篇 |
2017年 | 162篇 |
2016年 | 300篇 |
2015年 | 318篇 |
2014年 | 425篇 |
2013年 | 748篇 |
2012年 | 565篇 |
2011年 | 508篇 |
2010年 | 308篇 |
2009年 | 413篇 |
2008年 | 467篇 |
2007年 | 454篇 |
2006年 | 402篇 |
2005年 | 356篇 |
2004年 | 332篇 |
2003年 | 361篇 |
2002年 | 381篇 |
2001年 | 281篇 |
2000年 | 272篇 |
1999年 | 231篇 |
1998年 | 203篇 |
1997年 | 213篇 |
1996年 | 227篇 |
1995年 | 257篇 |
1994年 | 183篇 |
1993年 | 128篇 |
1992年 | 141篇 |
1991年 | 128篇 |
1990年 | 136篇 |
1989年 | 100篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 23篇 |
1985年 | 32篇 |
1984年 | 39篇 |
1983年 | 20篇 |
1982年 | 43篇 |
1981年 | 50篇 |
1980年 | 101篇 |
1979年 | 114篇 |
1978年 | 60篇 |
1977年 | 38篇 |
1976年 | 16篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
D. R. Gustafsson L. Lei K. Luo X. Chu X. Zhao Q. Zhang F. Zou 《Medical and veterinary entomology》2019,33(3):407-419
In total, 366 birds representing 55 species in 24 families and eight orders, were examined for chewing lice (Phthiraptera: Amblycera, Ischnocera) in two high‐altitude localities in Yunnan Province, China. In Ailaoshan, almost all of the birds examined were resident passeriforms, of which 36% were parasitized by chewing lice. In Jinshanyakou, most birds were on migration, and included both passerine and non‐passerine birds. Of the passerine birds caught in Jinshanyakou, only one bird (0.7%) was parasitized by chewing lice. The prevalence of Myrsidea and Brueelia‐complex lice on birds caught in Ailaoshan was higher than in previous reports. Of the chewing lice identifiable to species level, three represent new records for China: Actornithophilus hoplopteri (Mjöberg, 1910), Maculinirmus ljosalfar Gustafsson & Bush, 2017 and Quadraceps sinensis Timmermann, 1954. In total, 17 new host records are included, of which we describe two as new species in the Brueelia‐complex: Guimaraesiella (Cicchinella) ailaoshanensis sp. nov. ex Schoeniparus dubius dubius (Hume, 1874) and G. (C.) montisodalis sp. nov. ex Fulvetta manipurensis tonkinensis Delacour & Jabouille, 1930. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:9FC3D8EE‐2CED‐4DBE‐A1DB‐471B71260D27 . 相似文献
4.
5.
Jordi Corbera 《ZooKeys》2012,(235):73-85
A new cumacean genus and species, Ithyleucon sorbei
gen. et sp. n., was described from material collected in the southern margin of the Cap Ferret Canyon (Bay of Biscay, NE Atlantic). Although the new genus resembles Pseudoleucon Zimmer, 1903, in terms of the general aspect of the carapace and the pseudo-rostrum position, it shows important differences in the uropod structure and in the size of the antenna 1 accessory flagellum. In addition, some comments regarding the morphology of certain rare species (Mesolamprops denticulatus Ledoyer, 1983, Hemilamprops normani Bonnier, 1896 and Schizocuma spino-culatum (Jones, 1984)) are also provided. 相似文献
6.
Body size may be more important than species identity in determining species interactions and community structure. However, co‐occurrence of organisms has commonly been analysed from a taxonomic perspective and the body size is rarely taken into account. On six sampling occasions, we analysed patterns of killifish co‐occurrences in nestedness (tendency for less rich communities to be subsamples of the richest), checkerboard structure (tendency for species segregation), and modularity (tendency for groups to co‐occur more frequently than random expectation) in a pond metacommunity located in Uruguay. We contrasted co‐occurrence patterns among species and body size‐classes (individuals from different species were combined into size categories). The analysis was performed at two spatial scales: ponds (communities) and sample units within ponds. Observed nestedness was frequently smaller than the null expectation, with significantly greater deviations for body size‐classes than for species, and for sample units than for communities. At the sample unit level, individuals tended to segregate (i.e. clump into a checkerboard pattern) to a larger extent by body size rather than by taxonomy. Modularity was rarely detected, but nevertheless indicated a level of taxonomic organization not evident in nestedness or checkerboard indices. Identification of the spatial scale and organization at which ecological forces determine community structure is a basic requirement for advancement of robust theory. In our study system, these ecological forces probably structured the community by body sizes of interacting organisms rather than by species identities. 相似文献
7.
8.
9.
本文描述了发现于福建的冬青科冬青属2新种——泰宁冬青Ilex tainingensis G. S. He和南平冬青I. nanpingensis G. S. He,并分别说明两者与其他近缘种的区别要点。泰宁冬青与太平山冬青I. sugerokii Maxim.的区别在于前种小枝被毛,无棱槽,叶片宽卵圆形,花淡紫色,分核表面具细条纹,背后中部有一凹槽。南平冬青与拟榕叶冬青I. subficoidea S. Y. Hu区别在于前种果为椭圆形,较大,表面光滑无腺点,果梗长于1 cm,每分核上端有2尖角,均可以区别。 相似文献
10.
山西省异爪蝗属二新种(直翅目:网翅蝗科) 总被引:4,自引:0,他引:4
本文记述在晋南地区采到的异爪蝗属二新种,黑条异爪蝗Euchorthippus nigiliineatus sp.nov.及曲线异爪蝗Eochorthippus sinucarinatus sp.nov. 相似文献