全文获取类型
收费全文 | 5403篇 |
免费 | 753篇 |
国内免费 | 896篇 |
专业分类
7052篇 |
出版年
2024年 | 58篇 |
2023年 | 302篇 |
2022年 | 443篇 |
2021年 | 556篇 |
2020年 | 479篇 |
2019年 | 543篇 |
2018年 | 430篇 |
2017年 | 353篇 |
2016年 | 353篇 |
2015年 | 406篇 |
2014年 | 543篇 |
2013年 | 425篇 |
2012年 | 268篇 |
2011年 | 224篇 |
2010年 | 117篇 |
2009年 | 115篇 |
2008年 | 97篇 |
2007年 | 93篇 |
2006年 | 106篇 |
2005年 | 110篇 |
2004年 | 94篇 |
2003年 | 102篇 |
2002年 | 85篇 |
2001年 | 81篇 |
2000年 | 76篇 |
1999年 | 65篇 |
1998年 | 49篇 |
1997年 | 53篇 |
1996年 | 50篇 |
1995年 | 48篇 |
1994年 | 50篇 |
1993年 | 23篇 |
1992年 | 42篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1989年 | 23篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 9篇 |
1985年 | 20篇 |
1984年 | 27篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有7052条查询结果,搜索用时 15 毫秒
61.
应用自制复合菌剂M5于红螯螯虾(Cherax quadricarinatus)的高密度养殖系统中,通过分析肠道菌群并监测养殖水质,研究了复合菌剂作用的效果及潜在的机理。结果显示,复合菌剂M5的使用可显著降低养殖水环境的pH值,降低污染物NH+4、NO-2和COD的浓度,抑制弧菌属(Vibrio)中某些条件致病菌的生长。基于PICRUSt与KEGG数据库的功能预测及肠道菌群的群落分析,复合菌剂既可作为额外的营养补充物,缓解肠道群落之间对营养源的竞争,又可提高虾的消化能力、免疫力。新型复合菌剂M5可显著改善养殖水质并影响肠道菌群的组成与功能,从而提高养殖存活率。 相似文献
62.
Beno?te Méry Jean-Baptiste Guy Sophie Espenel Anne-Sophie Wozny Stéphanie Simonet Alexis Vallard Gersende Alphonse Dominique Ardail Claire Rodriguez-Lafrasse Nicolas Magné 《World journal of stem cells》2016,8(1):13-21
Head and neck squamous cell cancer(HNSCC) is the sixth most common cancer in the world. Effective therapeutic modalities such as surgery, radiation, chemotherapy and combinations of each are used in the management of the disease. In most cases, treatment fails to obtain total cancer cure. In recent years, it appears that one of the key determinants of treatment failure may be the presence of cancer stem cells(CSCs) that escape currently available therapies. CSCs form a small portion of the total tumor burden but may play a disproportionately important role in determining outcomes. CSCs have stem features such as self-renewal, high migration capacity, drug resistance, high proliferation abilities. A large body of evidence points to the fact that CSCs are particularly resistant to radiotherapy and chemotherapy. In HNSCC, CSCs have been increasingly shown to have an integral role in tumor initiation, disease progression, metastasis and treatment resistance. In the light of such observations, the present review summarizes biological characteristics of CSCs in HNSCC, outlines targeted strategies for the successful eradication of CSCs in HNSCC including targeting the self-renewal controlling pathways, blocking epithelial mesenchymal transition, niche targeting, immunotherapy approaches and highlights the need to better understand CSCs biology for new treatments modalities. 相似文献
63.
【目的】蜜蜂球囊菌(Ascosphaera apis)是一种专性侵染蜜蜂幼虫的致死性真菌病原。本研究旨在利用PacBio单分子实时(singlemoleculereal-time,SMRT)测序技术对蜜蜂球囊菌孢子(AaS)中基因的可变剪切(alternative splicing,AS)和可变多聚腺苷酸化(alternative polyadenylation,APA)以及长链非编码RNA (long non-coding RNA,lncRNA)进行鉴定和分析,进而揭示蜜蜂球囊菌孢子中转录组的复杂性。【方法】采用Suppa软件对蜜蜂球囊菌孢子中基因的AS事件进行鉴定。通过RT-PCR对不同类型的AS事件进行验证。采用TAPIS pipeline对蜜蜂球囊菌孢子基因的APA位点进行鉴定。利用MEME软件分析孢子全长转录本的poly(A)剪接位点上游50bp的序列特征并鉴定motif。联用CPC和CNCI软件和比对Swiss-prot数据库的方法预测lncRNA,取三者的交集作为高可信度的lncRNA集合。进一步比较lncRNA和mRNA的转录本长度,外显子数量与长度,内含子长度,GC含... 相似文献
65.
对大粉瘤菌Lycogalaflavofuscum的19SrDNA片段进行了克隆测序,序列长度为1443bp。同时将之与多头绒泡菌的相应序列进行了比较,其序列同源性为58.16%。 相似文献
66.
The complete amino acid sequence of apolipophorin-III (apoLp-III), a lipid-binding hemolymph protein from the greater wax
moth,Galleria mellonella, was determined by protein sequencing. The mature protein consists of 163 amino acid residues forming a protein of 18,075.5
Da. Its sequence is similar to apoLp-III from other Lepidopteran species, but remarkably different from the apoLp-IIIs of
insects from other orders. As shown by mass spectrometric analysis, the protein carries no modifications. Thus, all of its
known physiological functions, including its recently discovered immune response-stimulating activity, must reside in the
protein itself. 相似文献
67.
68.
O. I. Kiselev V. M. Blinov M. M. Pisareva V. A. Ternovoy A. P. Agafonov D. V. Saraev M. Ju. Eropkin T. G. Lobova V. A. Grigorieva M. P. Grudinin 《Molecular Biology》2008,42(1):70-78
In the second half of 2005, a large-scale outbreak of influenza in poultry and wild birds was caused by a highly pathogenic H5N1 influenza virus in Russia. The level of pathogenicity is a polygenic trait, and most individual genes contribute to the influenza A virus pathogenicity in birds, animals, and humans. The full-length nucleotide sequences were determined for H5N1 strains isolated in the Kurgan region (Western Siberia). The structure of viral proteins was analyzed using the deduced amino acid sequences. The receptor-binding site of hemagglutinin (HA) in strains A/chicken/Kurgan/05/2005 and A/duck/Kurgan/08/2005 was typical for avian influenza viruses and contained Glu and Gly at positions 226 and 228, respectively. The structure of the basic amino acid cluster located within the HA cleavage site was identical in all isolates: QGERRRKKR. According to the neuraminidase structure, all H5N1 isolates from the Kurgan region were assigned to the Z genotype. Amino acid residues typical for the avian influenza virus were revealed in 30 out of 32 positions of M1, M2, NP, PA, and PB2, determining the host range specificity. One of the strains contained Lys at position 627 of PB2. Isolates from the Kurgan region were shown to have a remantadine-sensitive genotype. Both strains contained Glu at position 92 of NS1, indicating that the virus is interferon-resistant. Phylogenetic analysis related the Kurgan isolates to subclade 2 of clade 2 of highly pathogenic H5N1 influenza viruses. 相似文献
69.
70.
《Cell》2022,185(23):4409-4427.e18