全文获取类型
收费全文 | 14619篇 |
免费 | 1347篇 |
国内免费 | 1585篇 |
出版年
2024年 | 43篇 |
2023年 | 219篇 |
2022年 | 436篇 |
2021年 | 885篇 |
2020年 | 630篇 |
2019年 | 729篇 |
2018年 | 695篇 |
2017年 | 498篇 |
2016年 | 669篇 |
2015年 | 978篇 |
2014年 | 1103篇 |
2013年 | 1239篇 |
2012年 | 1350篇 |
2011年 | 1277篇 |
2010年 | 753篇 |
2009年 | 705篇 |
2008年 | 770篇 |
2007年 | 648篇 |
2006年 | 639篇 |
2005年 | 411篇 |
2004年 | 411篇 |
2003年 | 383篇 |
2002年 | 328篇 |
2001年 | 241篇 |
2000年 | 199篇 |
1999年 | 195篇 |
1998年 | 163篇 |
1997年 | 116篇 |
1996年 | 107篇 |
1995年 | 95篇 |
1994年 | 73篇 |
1993年 | 64篇 |
1992年 | 84篇 |
1991年 | 58篇 |
1990年 | 52篇 |
1989年 | 50篇 |
1988年 | 41篇 |
1987年 | 28篇 |
1986年 | 22篇 |
1985年 | 28篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1975年 | 11篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
941.
HongYuan Wei YuXuan Ye HaiJian Huang MingShun Chen ZiXiang Yang XiaoMing Chen ChuanXi Zhang 《Ecology and evolution》2022,12(4)
The aphid Schlechtendalia chinensis is an economically important insect that can induce horned galls, which are valuable for the medicinal and chemical industries. Up to now, more than twenty aphid genomes have been reported. Most of the sequenced genomes are derived from free‐living aphids. Here, we generated a high‐quality genome assembly from a galling aphid. The final genome assembly is 271.52 Mb, representing one of the smallest sequenced genomes of aphids. The genome assembly is based on contig and scaffold N50 values of the genome sequence are 3.77 Mb and 20.41 Mb, respectively. Nine‐seven percent of the assembled sequences was anchored onto 13 chromosomes. Based on BUSCO analysis, the assembly involved 96.9% of conserved arthropod and 98.5% of the conserved Hemiptera single‐copy orthologous genes. A total of 14,089 protein‐coding genes were predicted. Phylogenetic analysis revealed that S. chinensis diverged from the common ancestor of Eriosoma lanigerum approximately 57 million years ago (MYA). In addition, 35 genes encoding salivary gland proteins showed differentially when S. chinensis forms a gall, suggesting they have potential roles in gall formation and plant defense suppression. Taken together, this high‐quality S. chinensis genome assembly and annotation provide a solid genetic foundation for future research to reveal the mechanism of gall formation and to explore the interaction between aphids and their host plants. 相似文献
942.
943.
病毒性疾病对人类和动物健康造成了重大威胁。由于现有的免疫接种和抗病毒疗法的局限性,开发安全、广谱、廉价的新型抗病毒制剂极为迫切。益生菌是摄入后能对机体产生多种有益作用的活性微生物,其抗病毒作用及潜在机制是当前的研究热点。本文介绍了益生菌通过促进肠道细胞的紧密连接和产生有利物质来维护机体黏膜屏障;与病毒竞争结合靶点或直接捕获并抑杀病毒;刺激机体免疫系统,调节固有免疫反应和适应性免疫反应;分泌具有抗病毒作用的代谢产物来发挥抗病毒作用及其作用机制,以期为益生菌的抗病毒相关研究提供参考。 相似文献
944.
提要准噶尔盆地西北缘玛湖凹陷风城组主要形成于碱湖环境,含有优质生烃母岩。对玛页1井风城组岩心样品的孢粉分析建立了Protohaploxypinus perfectus–Lunatisporites tersus (PT)孢粉组合。该组合包括20属29种孢粉化石。PT组合以双气囊具肋花粉占主导,蕨类孢子含量很低为特征;孢粉母体植物类群以裸子植物门种子蕨盾籽目为主,其次为松柏纲松柏目。该组合与准噶尔盆地南缘塔什库拉组上部至乌拉泊组的Crustaesporites–Protohaploxypinus–Hamiapollenites孢粉组合可以对比,均以双气囊具肋花粉为主要特征,又同时出现重要的属种Gardenasporites bilabiatus,Triangulisaccites boleensis和Hamiapollenites saccatus。孢粉地层学和同位素年代学资料表明,玛页1井风城组PT组合的时代很可能属于石炭纪宾夕法尼亚亚纪卡西莫夫期至二叠纪乌拉尔世阿瑟尔期,玛湖凹陷区整个风城组沉积时代晚于宾夕法尼亚亚纪巴什基尔期,其上部可能包含部分乌拉尔世阿瑟尔期沉积。风城组黑色页岩中... 相似文献
945.
946.
Monika Jain Bagher Golzarroshan ChiaLiang Lin Sashank Agrawal WeiHsuan Tang ChiuJu Wu Hanna S. Yuan 《Protein science : a publication of the Protein Society》2022,31(5)
Human Suv3 is a unique homodimeric helicase that constitutes the major component of the mitochondrial degradosome to work cooperatively with exoribonuclease PNPase for efficient RNA decay. However, the molecular mechanism of how Suv3 is assembled into a homodimer to unwind RNA remains elusive. Here, we show that dimeric Suv3 preferentially binds to and unwinds DNA–DNA, DNA–RNA, and RNA–RNA duplexes with a long 3′ overhang (≥10 nucleotides). The C‐terminal tail (CTT)‐truncated Suv3 (Suv3ΔC) becomes a monomeric protein that binds to and unwinds duplex substrates with ~six to sevenfold lower activities relative to dimeric Suv3. Only dimeric Suv3, but not monomeric Suv3ΔC, binds RNA independently of ATP or ADP, and is capable of interacting with PNPase, indicating that dimeric Suv3 assembly ensures its continuous association with RNA and PNPase during ATP hydrolysis cycles for efficient RNA degradation. We further determined the crystal structure of the apo‐form of Suv3ΔC, and SAXS structures of dimeric Suv3 and PNPase–Suv3 complex, showing that dimeric Suv3 caps on the top of PNPase via interactions with S1 domains, and forms a dumbbell‐shaped degradosome complex with PNPase. Overall, this study reveals that Suv3 is assembled into a dimeric helicase by its CTT for efficient and persistent RNA binding and unwinding to facilitate interactions with PNPase, promote RNA degradation, and maintain mitochondrial genome integrity and homeostasis. 相似文献
947.
948.
949.
950.
Tengfeng Yan Yinqiu Tan Gang Deng Zhiqiang Sun Baohui Liu Yixuan Wang Fanen Yuan Qian Sun Ping Hu Lun Gao Daofeng Tian Qianxue Chen 《Cell death & disease》2022,13(4)
Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor. The unregulated expression of Claudin-4 (CLDN4) plays an important role in tumor progression. However, the biological role of CLDN4 in GBM is still unknown. This study aimed to determine whether CLDN4 mediates glioma malignant progression, if so, it would further explore the molecular mechanisms of carcinogenesis. Our results revealed that CLDN4 was significantly upregulated in glioma specimens and cells. The inhibition of CLND4 expression could inhibit mesenchymal transformation, cell invasion, cell migration and tumor growth in vitro and in vivo. Moreover, combined with in vitro analysis, we found that CLDN4 can modulate tumor necrosis factor-α (TNF-α) signal pathway. Meanwhile, we also validated that the transforming growth factor-β (TGF-β) signal pathway can upregulate the expression of CLDN4, and promote the invasion ability of GBM cells. Conversely, TGF-β signal pathway inhibitor ITD-1 can downregulate the expression of CLDN4, and inhibit the invasion ability of GBM cells. Furthermore, we found that TGF-β can promote the nuclear translocation of CLDN4. In summary, our findings indicated that the TGF-β/CLDN4/TNF-α/NF-κB signal axis plays a key role in the biological progression of glioma. Disrupting the function of this signal axis may represent a new treatment strategy for patients with GBM.Subject terms: CNS cancer, Epithelial-mesenchymal transition 相似文献