全文获取类型
收费全文 | 4418篇 |
免费 | 446篇 |
国内免费 | 554篇 |
出版年
2024年 | 11篇 |
2023年 | 64篇 |
2022年 | 164篇 |
2021年 | 293篇 |
2020年 | 232篇 |
2019年 | 272篇 |
2018年 | 186篇 |
2017年 | 167篇 |
2016年 | 229篇 |
2015年 | 341篇 |
2014年 | 354篇 |
2013年 | 368篇 |
2012年 | 412篇 |
2011年 | 386篇 |
2010年 | 227篇 |
2009年 | 214篇 |
2008年 | 240篇 |
2007年 | 177篇 |
2006年 | 171篇 |
2005年 | 134篇 |
2004年 | 122篇 |
2003年 | 104篇 |
2002年 | 109篇 |
2001年 | 82篇 |
2000年 | 60篇 |
1999年 | 46篇 |
1998年 | 30篇 |
1997年 | 30篇 |
1996年 | 27篇 |
1995年 | 23篇 |
1994年 | 22篇 |
1993年 | 18篇 |
1992年 | 22篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有5418条查询结果,搜索用时 15 毫秒
61.
62.
Wang Zhen Huang Xu Liu Juan Xiao Feiyao Tian Miaomiao Ding Shenghua Shan Yang 《Biotechnology letters》2021,43(11):2161-2183
Biotechnology Letters - In this study, 44 flavone synthases (FNS) and flavonol synthases (FLS) from different origins were collected. The instability index and conserved domain of the enzymes were... 相似文献
63.
64.
Microbulbifer hainanensis sp. nov., a moderately halopilic bacterium isolated from mangrove sediment
Cheng Yuping Zhu Suting Guo Chaobo Xie Feilu Jung Dawoon Li Shengying Zhang Weiyan He Shan 《Antonie van Leeuwenhoek》2021,114(7):1033-1042
Antonie van Leeuwenhoek - A new bacterium was successfully isolated from a mangrove sediment sample in Haikou City, Hainan Province, China. The organism is a Gram-negative, rod-shaped, non-motile... 相似文献
65.
66.
67.
目的:微生物体内异戊二烯类化合物的前体物异戊烯焦磷酸酯的天然合成路径受到严格的代谢调控,因此限制了异戊二烯类化合物的高效生物合成,而新型异戊二烯醇利用途径独立于生物体内源性代谢路径,通过在微生物中引入IUP能够进行异戊烯焦磷酸酯的大量合成,从而促进异戊二烯类化合物的大量合成。方法:在油脂酵母解脂耶氏酵母中引入IUP,强化异戊烯焦磷酸酯生物合成,促进β-胡萝卜素的高效积累。结果:通过生物信息学的方法预测IUP中两个关键蛋白酿酒酵母来源的胆碱激酶ScCK和拟南芥来源的异戊烯磷酸激酶AtIPK,均为酸性亲水性蛋白,无跨膜区和信号肽,二者都具有疏松不稳定的结构特征,显著富集于磷酸类物质的合成通路中。在解脂耶氏酵母中利用同源重组技术引入外源β-胡萝卜素合成关键基因carRP和carB,强化甲羟戊酸途径的关键基因thmgR和ggs1,使工程菌株中积累2.68 mg/L β-胡萝卜素。通过Cre-loxP系统回收基因组上的ura标签,再将IUP进一步整合到工程菌株染色体上。当培养基中含有20 mM异戊二烯醇作为底物、碳氮比为4/3且发酵96 h后,重组解脂耶氏酵母中β-胡萝卜素的产量提高到410.2 mg/L,较原始工程菌的产量提高了近200倍。结论:IUP能够促进解脂耶氏酵母中β-胡萝卜素的高效积累,为利用IUP开展β-胡萝卜素和其他异戊二烯类化合物的高效生物合成提供新思路。 相似文献
68.
Ana Marcia Escocard de Azevedo Manhaes Fausto Andres Ortiz-Morea Ping He Libo Shan 《植物学报(英文版)》2021,63(1):79-101
As sessile organisms, plants are exposed to pathogen invasions and environmental fluctuations. To overcome the challenges of their surroundings, plants acquire the potential to sense endogenous and exogenous cues, resulting in their adaptability. Hence, plants have evolved a large collection of plasma membrane-resident receptors, including RECEPTOR-LIKE KINASEs(RLKs) and RECEPTOR-LIKE PROTEINs(RLPs) to perceive those signals and regulate plant growth,development, and immunity. The ability of RLKs and RLPs to recognize distinct ligands relies on diverse categories of extracellular domains evolved. Co-regulatory receptors are often required to associate with RLKs and RLPs to facilitate cellular signal transduction. RECEPTOR-LIKE CYTOPLASMIC KINASEs(RLCKs) also associate with the complex, bifurcating the signal to key signaling hubs, such as MITOGEN-ACTIVATED PROTEIN KINASE(MAPK) cascades, to regulate diverse biological processes. Here, we discuss recent knowledge advances in understanding the roles of RLKs and RLPs in plant growth, development, and immunity, and their connection with co-regulatory receptors, leading to activation of diverse intracellular signaling pathways. 相似文献
69.
甘蔗(Saccharum spp.)是世界也是中国主要的糖料作物.由甘蔗黑穗病菌(Sporisorium scitamineum)引起的甘蔗黑穗病是中国甘蔗生产上最主要的病害,每年造成重大损失.分泌蛋白在真菌侵染寄主植物与获取营养及病理过程起重要作用.本实验室在分析甘蔗黑穗病菌基因组与转录组数据时,发现1个与真菌细胞壁降解有关的β-1,6葡聚糖酶前体的基因Ssa4p.为了揭示Ssa4p对甘蔗黑穗病菌致病性和分泌蛋白组的影响,本研究利用CRISPR/Cas9和T-DNA双元载体所构建的甘蔗黑穗菌基因敲除系统,成功获得了Ssa4p基因的失活突变株.ΔSsa4p突变株(Δ35-Ssa4p)与野生型菌株JG36的配合能力降低且致病性减弱.用iTRAQ方法对Δ35-Ssa4p和野生型菌株的分泌蛋白组进行比较分析,共鉴定到蛋白质1430个,其中上调差异表达蛋白质685个,下调差异表达蛋白质745个.GO功能富集分析及KEGG分析表明,差异蛋白主要定位于无膜细胞器和核糖体,其功能包括参与核糖体、氨基糖和核苷酸糖代谢等生物学过程.本研究发现β-1,6葡聚糖前体影响植物病原真菌的分泌蛋白,加深了对真菌致病性调控机制的认识. 相似文献
70.
Jing Cui Kai Shan Qin Yang Yumin Qi Hongyan Qu Jiaqi Li Rong Wang Lingling Jia Wei Chen Ninghan Feng Yong Q. Chen 《Journal of cellular and molecular medicine》2021,25(12):5586-5601
Alternative polarization of macrophages regulates multiple biological processes. While M1-polarized macrophages generally mediate rapid immune responses, M2-polarized macrophages induce chronic and mild immune responses. In either case, polyunsaturated fatty acid (PUFA)-derived lipid mediators act as both products and regulators of macrophages. Prostaglandin E3 (PGE3) is an eicosanoid derived from eicosapentaenoic acid, which is converted by cyclooxygenase, followed by prostaglandin E synthase successively. We found that PGE3 played an anti-inflammatory role by inhibiting LPS and interferon-γ-induced M1 polarization and promoting interleukin-4-mediated M2 polarization (M2a). Further, we found that although PGE3 had no direct effect on the growth of prostate cancer cells in vitro, PGE3 could inhibit prostate cancer in vivo in a nude mouse model of neoplasia. Notably, we found that PGE3 significantly inhibited prostate cancer cell growth in a cancer cell-macrophage co-culture system. Experimental results showed that PGE3 inhibited the polarization of tumour-associated M2 macrophages (TAM), consequently producing indirect anti-tumour activity. Mechanistically, we identified that PGE3 regulated the expression and activation of protein kinase A, which is critical for macrophage polarization. In summary, this study indicates that PGE3 can selectively promote M2a polarization, while inhibiting M1 and TAM polarization, thus exerting an anti-inflammatory effect and anti-tumour effect in prostate cancer. 相似文献