全文获取类型
收费全文 | 9484篇 |
免费 | 417篇 |
国内免费 | 954篇 |
出版年
2024年 | 15篇 |
2023年 | 95篇 |
2022年 | 126篇 |
2021年 | 175篇 |
2020年 | 162篇 |
2019年 | 198篇 |
2018年 | 185篇 |
2017年 | 182篇 |
2016年 | 290篇 |
2015年 | 322篇 |
2014年 | 454篇 |
2013年 | 773篇 |
2012年 | 583篇 |
2011年 | 539篇 |
2010年 | 329篇 |
2009年 | 441篇 |
2008年 | 479篇 |
2007年 | 474篇 |
2006年 | 414篇 |
2005年 | 379篇 |
2004年 | 345篇 |
2003年 | 359篇 |
2002年 | 389篇 |
2001年 | 286篇 |
2000年 | 279篇 |
1999年 | 232篇 |
1998年 | 207篇 |
1997年 | 212篇 |
1996年 | 221篇 |
1995年 | 262篇 |
1994年 | 187篇 |
1993年 | 133篇 |
1992年 | 142篇 |
1991年 | 129篇 |
1990年 | 137篇 |
1989年 | 102篇 |
1988年 | 23篇 |
1987年 | 21篇 |
1986年 | 21篇 |
1985年 | 33篇 |
1984年 | 39篇 |
1983年 | 21篇 |
1982年 | 44篇 |
1981年 | 50篇 |
1980年 | 100篇 |
1979年 | 113篇 |
1978年 | 60篇 |
1977年 | 37篇 |
1976年 | 15篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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
22.
23.
Deborah Lupton 《Bioethics》2020,34(9):969-976
Digital health technologies are often advocated as a way of helping people monitor, promote and manage their health, care for others and reduce the burden on healthcare systems. Yet these technologies have also been subject to criticism for limiting human flourishing and exacerbating socioeconomic disadvantage. Bioethical appraisals of digital health technologies tend to take a conventional risk-benefit approach, positioning the human subject as a rational, autonomous agent who is acted on by technologies. In this paper, I present a case for adopting an alternative more-than-human perspective on bioethics. A more-than-human approach considers human-technological assemblages and agencies as distributed, relational, situated and emergent. To illustrate the insights that this perspective can offer, I draw on the findings of four empirical projects I have conducted on people’s use of digital devices and platforms used for health-related purposes, including social media groups and online forums, mobile apps and wearable devices. I conclude with the argument that a more-than-human approach to bioethics can begin to incorporate a new ‘zoë ethics’ that can acknowledge and address the deeper affective, multisensory and relational dimensions of humans’ encounters with and enactments of material things and nonhuman creatures. 相似文献
24.
25.
A newly discovered iron-containing protein, isolated from the bacterium Desulfovibrio vulgaris (Hildenborough, NCIB 8303), has been crystallized. The molecule appears to be a dimer of mass 44kDa. This protein has iron centers with spectrascopic similarities to those in rubredoxins and in hemerythrins. The X-ray diffraction shows symmetry consistent with space group I222 or I212121. Cell parameters are a = 49.2 A, b = 81.3 A, c = 100.1 A, and alpha, beta, gamma = 90 degrees. X-ray diffraction data have been collected to 3.0 A, and a search for useful heavy atom derivatives is in progress for the analysis of the crystal structure of this Fe-protein. 相似文献
26.
27.
Abstract In this paper a new species, namely Arenetra genangustu , collected from Tonghua, Jilin Province, is described. 相似文献
28.
29.
Wilhelm Sauer 《Plant Systematics and Evolution》1987,155(1-4):257-276
Comparative morphological, karyological and chorological studies prove the distinctness of the SE European and Asiatic populations ofPulmonaria mollis s.l., to be treated asP. dacica (Figs. 4, 5).P. mollis s.str. is interpreted as a relatively young taxon, which probably has evolved from an older stock ofP. dacica ancestors during the Pleistocene (Figs. 6, 8) and might have migrated, perhaps with oak woodland communities, from SE to C. Europe. A similar evolution can be postulated for S—SE European dysploidP. rubra-carnica-stiriaca-vallarsae group; this may have involved still unknown tetraploids (P. carnica?, Fig. 7). This group is linked via the hypertriploid speciesP. vallarsae with theP. saccharata group and at least the eastern species of theP. australis group. The monotypic genusParaskevia apparently marks the earliest divergence from the common Tertiary ancestral stock (Fig. 8). It exhibits a tetraploid chromosome number (2n = 28) but has preserved the most primitive characters. — Some comments on the systematics and nomenclature ofP. australis andParaskevia are added. 相似文献
30.
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