全文获取类型
收费全文 | 3834篇 |
免费 | 421篇 |
国内免费 | 609篇 |
出版年
2024年 | 35篇 |
2023年 | 95篇 |
2022年 | 203篇 |
2021年 | 284篇 |
2020年 | 209篇 |
2019年 | 222篇 |
2018年 | 242篇 |
2017年 | 153篇 |
2016年 | 184篇 |
2015年 | 283篇 |
2014年 | 367篇 |
2013年 | 338篇 |
2012年 | 387篇 |
2011年 | 340篇 |
2010年 | 232篇 |
2009年 | 210篇 |
2008年 | 216篇 |
2007年 | 174篇 |
2006年 | 150篇 |
2005年 | 104篇 |
2004年 | 88篇 |
2003年 | 96篇 |
2002年 | 61篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 24篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有4864条查询结果,搜索用时 217 毫秒
941.
Jiangang Liu Dapeng Wang Yanyan Li Hui Yao Nan Zhang Xuewen Zhang Fangping Zhong Yulun Huang 《Cell biochemistry and biophysics》2018,76(1-2):83-90
The human pituitary tumor-transforming gene is an oncogenic protein which serves as a central hub in the cellular signaling network of medulloblastoma. The protein contains two vicinal PxxP motifs at its C terminus that are potential binding sites of peptide-recognition SH3 domains. Here, a synthetic protocol that integrated in silico analysis and in vitro assay was described to identify the SH3-binding partners of pituitary tumor-transforming gene in the gene expression profile of medulloblastoma. In the procedure, a variety of structurally diverse, non-redundant SH3 domains with high gene expression in medulloblastoma were compiled, and their three-dimensional structures were either manually retrieved from the protein data bank database or computationally modeled through bioinformatics technique. The binding capability of these domains towards the two PxxP-containing peptides m1p: 161LGPPSPVK168 and m2p: 168KMPSPPWE175 of pituitary tumor-transforming gene were ranked by structure-based scoring and fluorescence-based assay. Consequently, a number of SH3 domains, including MAP3K and PI3K, were found to have moderate or high affinity for m1p and/or m2p. Interestingly, the two overlapping peptides exhibits a distinct binding profile to these identified domain partners, suggesting that the binding selectivity of m1p and m2p is optimized across the medulloblastoma expression spectrum by competing for domain candidates. In addition, two redesigned versions of m1p peptide ware obtained via a structure-based rational mutation approach, which exhibited an increased affinity for the domain as compared to native peptide. 相似文献
942.
A bifunctional hybrid electrolyte composed of mesoporous silica nanosheets and liquid electrolyte is achieved for lithium–sulfur (Li–S) batteries. This hybrid electrolyte possesses abundant mesopores (2.8 nm), thin feature (20 µm), and high ionic conductivity (1.17 × 10?1 mS cm?1) as well as a low interfacial resistance with electrodes. Such unique features not only enable the efficient inhibition of the growth of lithium dendrites, but also significantly prevents polysulfide shuttling. Consequently, a Li–S battery with this hybrid electrolyte exhibits a relatively high reversible capacity and good capacity retention. 相似文献
943.
Zhong‐Hui Shen Jian‐Jun Wang Jian‐Yong Jiang Yuan‐Hua Lin Ce‐Wen Nan Long‐Qing Chen Yang Shen 《Liver Transplantation》2018,8(20)
Polymer‐based dielectrics are attracting increasing attention due to their high‐density energy storage. However, mitigating the heat generation in real capacitors has been a challenge. Here an electrothermal breakdown phase‐field model is developed to fundamentally understand the thermal effects on the dielectric breakdown of polymer‐based dielectrics in real capacitor configurations including the increase in the dielectric loss and the decrease in the breakdown strength. While both enhancing the thermal conductivity and reducing the electrical conductivity of the polymer nanocomposites can reduce the thermal effects, it is found that reducing the electrical conductivity is more effective. This work is expected to not only stimulate attention to the thermal effects in polymer‐based dielectrics but also provide a fundamental guidance to mitigate the heat‐induced deterioration of breakdown strength. 相似文献
944.
Yanling Yang Yuening Cheng Nan Li Shipeng Cheng Li Guo Yucheng Zhou Haiwei Zhang Xinyuan Zhang Linzhu Ren 《中国病毒学》2018,33(6):561-564
正Dear Editor,Mink circovirus (MiCV), which is clustered in the genus Circovirus of the family Circoviridae, was first described in minks from farms in Dalian, China in 2013 (Lian et al.2014). The complete single-stranded circular genome of the virus is 1,753 nucleotides long and contains two major open reading frames (ORFs), designated ORF1 (Rep gene)and ORF2 (Cap gene)(Lian et al. 2014; Ge et al. 2018).Sequence analysis has shown that MiCV is most closely 相似文献
945.
The rational design of multiple molecular module-based assemblies for simultaneously improving rice yield and grain quality 总被引:1,自引:0,他引:1
Kun Wu Xiaopeng Xu Nan Zhong Haixiang Huang Jianping Yu Yafeng Ye Yuejin Wu Xiangdong Fu 《遗传学报》2018,45(6):337-341
正Rice is one of the most important staple food for over half of the world's population,and a substantial increase in productivity and quality of rice grain will be required to feed a growing human population.Grain size and shape are the two important components contributing to grain yield and quality,because they impact both yield potential and end-use quality.Over the past 50 years,the 相似文献
946.
为了促进亮氨酸脱氢酶在Bacillus subtilis中高效表达,采取在质粒pMA5自带的启动子P_(HpaⅡ)之后分别添加诱导型和组成型启动子,考察双启动子对酶表达的影响。选取2种诱导型启动子(P_(grac)、P_(gl-M1))和4种组成型启动子(P_(43)、P_(laps)、P_(HpaⅡ)、P_(amyQ))进行构建表达,其中组成型启动子P_(amyQ)与P_(HpaⅡ)构成的双启动子效果最好,有效地将胞外活性提高到31. 24U/ml,是单启动子PHpaⅡ的3. 4倍。在以上最优双启动子的基础上分别融合Sec途径和Tat途径的4种信号肽,但信号肽与双启动子共同作用并没有获得更高的酶活性。选用酶活最高的双启动子突变菌株Bacillus subtilis168/pW6(P_(HpaⅡ)-P_(amyQ))进行7. 5L发酵罐补料发酵产酶研究,LeuDH酶活达到217. 96U/ml,是摇瓶水平的6. 97倍,对工业上产亮氨酸脱氢酶有一定参考价值。 相似文献
947.
Caixia Xi Nan Liu Fei Liang Xiao Zhao Juan Long Fang Yuan Song Yun Yuying Sun Yongzhi Xi 《中国科学:生命科学英文版》2018,61(7):815-825
Effective treatment of rheumatoid arthritis can be mediated by native chicken type II collagen (nCCII), recombinant peptide containing nCCII tolerogenic epitopes (CTEs), or a therapeutic DNA vaccine encoding the full-length CCOL2A1 cDNA. As recombinant CCII (rCCII) might avoid potential pathogenic virus contamination during nCCII preparation or chromosomal integration and oncogene activation associated with DNA vaccines, here we evaluated the importance of propeptide and telopeptide domains on rCCII triple helix molecular assembly. We constructed pC- and pN-procollagen (without N- or C-propeptides, respectively) as well as CTEs located in the triple helical domain lacking both propeptides and telopeptides, and expressed these in yeast Pichia pastoris host strain GS115 (his4, Mut+) simultaneously with recombinant chicken prolyl-4-hydroxylase α and β subunits. Both pC- and pN-procollagen monomers accumulated inside P. pastoris cells, whereas CTE was assembled into homotrimers with stable conformation and secreted into the supernatants, suggesting that the large molecular weight pC-or pN-procollagens were retained within the endoplasmic reticulum whereas the smaller CTEs proceeded through the secretory pathway. Furthermore, resulting recombinant chicken type II collagen pCα1(II) can induced collagen-induced arthritis (CIA) rat model, which seems to be as effective as the current standard nCCII. Notably, protease digestion assays showed that rCCII could assemble in the absence of C- and N-propeptides or telopeptides. These findings provide new insights into the minimal structural requirements for rCCII expression and folding. 相似文献
948.
正Microorganisms live in almost every habitat on the earth from the poles to the equator,from forest to desert,from mountain to deep sea,from geysers to karst structures,as well as the body of almost all multicellular organisms from plants to animals.Essentially,species among the microbial populations interact in different ways,as predators and prey,or as symbionts in the form of communities,so adapt to hosts 相似文献
949.
Pentatricopeptide repeat (PPR) gene family plays an essential role in the regulation of plant growth and organelle gene expression. Some PPR genes are related to fertility restoration in plant, but there is no detailed information in Gossypium. In the present study, we identified 482 and 433 PPR homologues in Gossypium raimondii (\(\hbox {D}_{5}\)) and G. arboreum (\(\hbox {A}_{2}\)) genomes, respectively. Most PPR homologues showed an even distribution on the whole chromosomes. Given an evolutionary analysis to PPR genes from G. raimondii (\(\hbox {D}_{5}\)), G. arboreum (\(\hbox {A}_{2}\)) and G. hirsutum genomes, eight PPR genes were clustered together with restoring genes of other species. Most cotton PPR genes were qualified with no intron, high proportion of \(\upalpha \)-helix and classical tertiary structure of PPR protein. Based on bioinformatics analyses, eight PPR genes were targeted in mitochondrion, encoding typical P subfamily protein with protein binding activity and organelle RNA metabolism in function. Further verified by RNA-seq and quantitative real-time PCR (qRT-PCR) analyses, two PPR candidate genes, Gorai.005G0470 (\(\hbox {D}_{5}\)) and Cotton_A_08373 (\(\hbox {A}_{2}\)), were upregulated in fertile line than sterile line. These results reveal new insights into PPR gene evolution in Gossypium. 相似文献
950.
Tao Chen Zhibiao Nan Xingxu Zhang Fujiang Hou Michael Christensen Carol Baskin 《Plant and Soil》2018,422(1-2):155-168