全文获取类型
收费全文 | 1143篇 |
免费 | 86篇 |
国内免费 | 105篇 |
专业分类
1334篇 |
出版年
2024年 | 6篇 |
2023年 | 26篇 |
2022年 | 56篇 |
2021年 | 53篇 |
2020年 | 48篇 |
2019年 | 47篇 |
2018年 | 50篇 |
2017年 | 33篇 |
2016年 | 37篇 |
2015年 | 80篇 |
2014年 | 79篇 |
2013年 | 92篇 |
2012年 | 102篇 |
2011年 | 84篇 |
2010年 | 49篇 |
2009年 | 34篇 |
2008年 | 60篇 |
2007年 | 50篇 |
2006年 | 41篇 |
2005年 | 27篇 |
2004年 | 23篇 |
2003年 | 26篇 |
2002年 | 33篇 |
2001年 | 16篇 |
2000年 | 20篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 10篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 8篇 |
排序方式: 共有1334条查询结果,搜索用时 0 毫秒
51.
52.
53.
Qing Yao Li Zhang Xiaobo Wan Jing Chen Liyan Hu Xiaojun Ding Lin Li Jayashree Karar Hongzhuang Peng She Chen Niu Huang Frank J. Rauscher III Feng Shao 《PLoS pathogens》2014,10(11)
Enteropathogenic E. coli (EPEC) and related enterobacteria rely on a type III secretion system (T3SS) effector NleE to block host NF-κB signaling. NleE is a first in class, novel S-adenosyl-L-methionine (SAM)-dependent methyltransferase that methylates a zinc-coordinating cysteine in the Npl4-like Zinc Finger (NZF) domains in TAB2/3 adaptors in the NF-κB pathway, but its mechanism of action and other human substrates are unknown. Here we solve crystal structure of NleE-SAM complex, which reveals a methyltransferase fold different from those of known ones. The SAM, cradled snugly at the bottom of a deep and narrow cavity, adopts a unique conformation ready for nucleophilic attack by the methyl acceptor. The substrate NZF domain can be well docked into the cavity, and molecular dynamic simulation indicates that Cys673 in TAB2-NZF is spatially and energetically favorable for attacking the SAM. We further identify a new NleE substrate, ZRANB3, that functions in PCNA binding and remodeling of stalled replication forks at the DNA damage sites. Specific inactivation of the NZF domain in ZRANB3 by NleE offers a unique opportunity to suggest that ZRANB3-NZF domain functions in DNA repair processes other than ZRANB3 recruitment to DNA damage sites. Our analyses suggest a novel and unexpected link between EPEC infection, virulence proteins and genome integrity. 相似文献
54.
Fusicoccin (FC) treatment prevents dark‐induced stomatal closure, the mechanism of which is still obscure. By using pharmacological approaches and laser‐scanning confocal microscopy, the relationship between FC inhibition of dark‐induced stomatal closure and the hydrogen peroxide (H2O2) levels in guard cells in broad bean was studied. Like ascorbic acid (ASA), a scavenger of H2O2 and diphenylene iodonium (DPI), an inhibitor of H2O2‐generating enzyme NADPH oxidase, FC was found to inhibit stomatal closure and reduce H2O2 levels in guard cells in darkness, indicating that FC‐caused inhibition of dark‐induced stomatal closure is related to the reduction of H2O2 levels in guard cells. Furthermore, like ASA, FC not only suppressed H2O2‐induced stomatal closure and H2O2 levels in guard cells treated with H2O2 in light, but also reopened the stomata which had been closed by darkness and reduced the level of H2O2 that had been generated by darkness, showing that FC causes H2O2 removal in guard cells. The butyric acid treatment simulated the effects of FC on the stomata treated with H2O2 and had been closed by dark, and on H2O2 levels in guard cells of stomata treated with H2O2 and had been closed by dark, and both FC and butyric acid reduced cytosol pH in guard cells of stomata treated with H2O2 and had been closed by dark, which demonstrates that cytosolic acidification mediates FC‐induced H2O2 removal. Taken together, our results provide evidence that FC causes cytosolic acidification, consequently induces H2O2 removal, and finally prevents dark‐induced stomatal closure. 相似文献
55.
56.
57.
植物病原菌侵染寄主的过程就是病原菌和寄主植物相互作用的过程.在这个相互作用过程中,Ⅲ型分泌系统和Ⅲ效应物与病原菌致病密切相关.大部分革兰氏阴性植物病原菌通过Ⅲ型分泌系统定向的把效应物蛋白传递到宿主细胞,效应物蛋白进入植物体引起致病或过敏反应.本研究将百日咳杆菌的腺苷酸环化酶基因连接至含启动子的pLAFRJ载体上,从而构建出一个新的体外快速鉴定Ⅲ型效应物的报告质粒pJJA,并用已鉴定为Ⅲ型效应物基因的十字花科黑腐病菌XC1553的启动子和信号区验证该报告质粒,证明这个系统是可以工作的.该报告质粒为进一步精确筛选鉴定十字花科黑腐病菌Ⅲ型效应物提供了材料. 相似文献
58.
Genetic structure and phylogenetic relationships of Ralstonia solanacearum strains from diverse origins in Guangdong Province,China 下载免费PDF全文
Bacterial wilt, caused by Ralstonia solanacearum species complex is a key yield‐limiting factor on crops in Guangdong province, China. The genetic diversity of 110 R. solanacearum strains collected from 16 host plants in different areas of Guangdong province was analysed using biovar and phylotype classification schemes. Of 110 strains, fifty‐five strains belong to biovar 3, fifty‐two strains belong to biovar 4, two strains belong to biovar 2 and one strain belonged to biovar 1. Phylotype‐specific multiplex PCR showed that 108 strains belonged to phylotype I (biovars 1, 3, 4) and two strains belonged to phylotype II (biovar 2). The result of phylogenetic relationships analysis based on egl gene sequences demonstrated that 108 strains of phylotype I were grouped into nine previously described sequevars and a new sequevar 57, and two strains of phylotype II were grouped into sequevar 1. Sequevars 15, 34 and 44 widely distributed in Guangdong were predominant sequevars. Sequevar 45 was first reported on potato and pumpkin in China. These results revealed the genetic structure and phylogenetic relationships of R. solanacearum population in Guangdong and will be helpful in bacterial wilt‐resistance breeding. 相似文献
59.
通过观察miR-125b-5p对分枝杆菌在宿主细胞和小鼠体内存活情况的影响,探究其在抗结核免疫过程中的作用。采用不同培养基对分枝杆菌进行培养并计数;以1640培养基加10%胎牛血清培养所有实验用细胞。将终浓度50 nmol/L的miR-125b-5p 模拟物、miR-125b-5p 抑制剂及磷酸盐缓冲液(PBS)对照加入细胞后,在不同时间点收集细胞。用分枝杆菌分别感染宿主细胞(A549、THP-1和RAW264.7)以及C57BL/6小鼠。采用定量聚合酶链反应检测miR-125b-5p的表达量。结果miR-125b-5p在分枝杆菌感染的多种宿主细胞及小鼠中都显著上调表达,其中小鼠肺部的表达量提高了约15倍。分别转染模拟物和抑制剂后,再用分枝杆菌感染细胞,结果发现miR-125b-5p可促进分枝杆菌在宿主细胞内的生长。当miR-125b-5p抑制剂注射到卡介苗(BCG)感染的小鼠体内时,小鼠体内的细菌载量显著降低(P<0.05)。本研究证明miR-125b-5p可调控分枝杆菌在宿主细胞及小鼠体内的生长,在抗结核免疫过程中发挥了重要作用。进一步对其作用机制的深入研究将为临床结核病的治疗提供理论指导。 相似文献
60.
亚临床甲亢和甲减发病的实验室调查 总被引:2,自引:1,他引:2
目的 探讨本地区亚临床甲状腺疾病的发病情况。 方法 随机抽样 2 550例健康体检者作甲状腺功能检测 ,以促甲状腺素 ( TSH)水平异常的检出率来判断亚临床甲状腺疾病的发病率。 结果 亚临床甲亢的检出率为5.4 5% ,亚临床甲减的检出率为 6 .98% ;两种疾病 T3、T4、FT3、 FT4 和 TSH的均数比较具有非常显著性差异 ( P <0 .0 1)。 结论 本地区具有亚临床甲状腺疾病的发病现象 ,亚临床甲减的发病率比亚临床甲亢稍高 相似文献