全文获取类型
收费全文 | 39058篇 |
免费 | 3100篇 |
国内免费 | 3305篇 |
出版年
2024年 | 61篇 |
2023年 | 513篇 |
2022年 | 815篇 |
2021年 | 2201篇 |
2020年 | 1537篇 |
2019年 | 1993篇 |
2018年 | 1823篇 |
2017年 | 1254篇 |
2016年 | 1792篇 |
2015年 | 2535篇 |
2014年 | 3036篇 |
2013年 | 3251篇 |
2012年 | 3660篇 |
2011年 | 3328篇 |
2010年 | 1906篇 |
2009年 | 1805篇 |
2008年 | 2115篇 |
2007年 | 1824篇 |
2006年 | 1525篇 |
2005年 | 1207篇 |
2004年 | 984篇 |
2003年 | 908篇 |
2002年 | 688篇 |
2001年 | 609篇 |
2000年 | 565篇 |
1999年 | 567篇 |
1998年 | 349篇 |
1997年 | 349篇 |
1996年 | 312篇 |
1995年 | 283篇 |
1994年 | 264篇 |
1993年 | 195篇 |
1992年 | 246篇 |
1991年 | 220篇 |
1990年 | 167篇 |
1989年 | 127篇 |
1988年 | 105篇 |
1987年 | 88篇 |
1986年 | 65篇 |
1985年 | 64篇 |
1984年 | 33篇 |
1983年 | 40篇 |
1982年 | 19篇 |
1981年 | 19篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
1.
2.
The functioning of the vertebrate eye depends on its absolute size, which is presumably adapted to specific needs. Eye size variation in lidless and spectacled colubrid snakes was investigated, including 839 specimens belonging to 49 genera, 66 species and subspecies. Variations of adult eye diameters (EDs) in both absolute and relative terms between species were correlated with parameters reflecting behavioral ecology. In absolute terms, eye of arboreal species was larger than in terrestrial and semiaquatic species. For diurnal species, EDs of terrestrial species do not differ from semiaquatic species; for nocturnal species the ED of terrestrial species is larger than fossorial species but not different from semiaquatic species. In relative terms, ED did not differ significantly by habitat for diurnal species. Although the ED of terrestrial species is larger than fossorial species there were no differences for nocturnal species between semiaquatic and fossorial snakes. In contrast to other vertebrates studied to date, colubrid EDs in absolute and relative terms are larger in diurnal than in nocturnal species. These observations suggest that among colubrid snakes, eye size variation reflects adaptation to specific habitats, foraging strategies and daily activities, independently of phylogeny. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc. 相似文献
3.
Benjamin C. Blum Weiwei Lin Matthew L. Lawton Qian Liu Julian Kwan Isabella Turcinovic Ryan Hekman Pingzhao Hu Andrew Emili 《Molecular & cellular proteomics : MCP》2022,21(1):100189
Metabolism is recognized as an important driver of cancer progression and other complex diseases, but global metabolite profiling remains a challenge. Protein expression profiling is often a poor proxy since existing pathway enrichment models provide an incomplete mapping between the proteome and metabolism. To overcome these gaps, we introduce multiomic metabolic enrichment network analysis (MOMENTA), an integrative multiomic data analysis framework for more accurately deducing metabolic pathway changes from proteomics data alone in a gene set analysis context by leveraging protein interaction networks to extend annotated metabolic models. We apply MOMENTA to proteomic data from diverse cancer cell lines and human tumors to demonstrate its utility at revealing variation in metabolic pathway activity across cancer types, which we verify using independent metabolomics measurements. The novel metabolic networks we uncover in breast cancer and other tumors are linked to clinical outcomes, underscoring the pathophysiological relevance of the findings. 相似文献
4.
5.
目的 研究严重急性呼吸综合征冠状病毒2(SARS-CoV-2)膜蛋白对宿主细胞mRNA前体(pre-mRNA)3"非翻译区(UTR)加工的影响。方法 本研究以人肺上皮细胞系A549为模型,利用瞬时转染在细胞内过表达SARS-CoV-2膜蛋白;利用RNA-Seq测序技术及生物信息学分析方法,系统性描绘宿主细胞选择性多聚腺苷酸化(alternative polyadenylation,APA)事件;Metascape数据库对发生显著APA变化的基因进行功能富集分析;RT-qPCR验证靶基因3"UTR长度变化;蛋白质免疫印迹(Western blot)检测目的蛋白表达水平。结果 SARS-CoV-2膜蛋白外源表达后宿主细胞内共813个基因发生显著APA变化。GO和KEGG分析显示,差异APA基因广泛参与有丝分裂细胞周期、调节细胞应激等生物过程,涉及病毒感染和蛋白质加工等。从中进一步筛选出AKT1基因,在IGV软件中显示3"UTR延长;RT-qPCR验证AKT1基因的3"UTR长度变化趋势;Western blot结果显示AKT1蛋白磷酸化水平增加。结论 SARS-CoV-2膜蛋白潜在影响宿主pre-mRNA的3"UTR加工,其中参与多种病毒性生物过程的AKT1基因 3"UTR延长,且其编码的蛋白质功能在细胞内被激活。 相似文献
6.
7.
8.
9.
Neurochemical Research - Inhalation anesthetic isoflurane may cause an increased risk of cognitive impairment. Previous studies have indicated that this cognitive decline is associated with... 相似文献
10.
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