全文获取类型
收费全文 | 6104篇 |
免费 | 483篇 |
国内免费 | 597篇 |
出版年
2024年 | 10篇 |
2023年 | 59篇 |
2022年 | 149篇 |
2021年 | 339篇 |
2020年 | 242篇 |
2019年 | 312篇 |
2018年 | 293篇 |
2017年 | 227篇 |
2016年 | 303篇 |
2015年 | 395篇 |
2014年 | 517篇 |
2013年 | 463篇 |
2012年 | 632篇 |
2011年 | 551篇 |
2010年 | 380篇 |
2009年 | 305篇 |
2008年 | 343篇 |
2007年 | 286篇 |
2006年 | 212篇 |
2005年 | 192篇 |
2004年 | 133篇 |
2003年 | 134篇 |
2002年 | 100篇 |
2001年 | 75篇 |
2000年 | 65篇 |
1999年 | 55篇 |
1998年 | 21篇 |
1997年 | 32篇 |
1996年 | 21篇 |
1995年 | 26篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 31篇 |
1991年 | 37篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 10篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1980年 | 11篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1971年 | 5篇 |
1967年 | 4篇 |
排序方式: 共有7184条查询结果,搜索用时 31 毫秒
991.
992.
993.
Nilaparvata lugens and Sogatella furcifera are two primary planthoppers on rice throughout Asian countries and areas. Neonicotinoid insecticides, such as imidacloprid (IMI), have been extensively used to control rice planthoppers and IMI resistance consequently occurred with an important mechanism from the over‐expression of P450 genes. The induction of P450 genes by IMI may increase the ability to metabolize this insecticide in planthoppers and increase the resistance risk. In this study, the induction of P450 genes was compared in S. furcifera treated with IMI and nitromethyleneimidazole (NMI), in two planthopper species by IMI lethal dose that kills 85% of the population (LD85), and in N. lugens among three IMI doses (LD15, LD50 and LD85). When IMI and NMI at the LD85 dose were applied to S. furcifera, the expression changes in most P450 genes were similar, including the up‐regulation of nine genes and down‐regulation of three genes. In terms of the expression changes in 12 homologous P450 genes between N. lugens and S. furcifera treated with IMI at the LD85 dose, 10 genes had very similar patterns, such as up‐regulation in seven genes, down‐regulation in one gene and no significant changes in two genes. When three different IMI doses were applied to N. lugens, the changes in P450 gene expression were much different, such as up‐regulation in four genes at all doses and dose‐dependent regulation of the other nine genes. For example, CYP6AY1 could be induced by all IMI doses, while CYP6ER1 was only up‐regulated by the LD50 dose, although both genes were reported important in IMI resistance. In conclusion, P450 genes in two planthopper species showed similar regulation patterns in responding to IMI, and the two neonicotinoid insecticides had similar effects on P450 gene expression, although the regulation was often dose‐dependent. 相似文献
994.
995.
Xiuyu Xu Changpin Zhou Yong Zhang Weiqiang Zhang Xianhua Gan Huaxin Zhang Yong Guo Siming Gan 《Tree Genetics & Genomes》2018,14(2):30
Simple sequence repeat (SSR) markers are very useful for genetic applications in plants, but SSR resource for the important tree genus Casuarina L. ex Adans. is still limited. In this study, we report a novel set of 223 SSR markers in Casuarina developed from expressed sequence tag (EST) resource of GenBank. The 223 EST-SSR markers were polymorphic among 10 unrelated individuals of C. equisetifolia L. Johnson, with the number of alleles per locus (Na), observed heterozygosity (Ho), expected heterozygosity (He), and polymorphic information content (PIC) averaging at 5.5, 0.72, 0.86, and 0.63, respectively. The rates of cross-species transferability ranged from 96.9% (C. glauca Sieber ex Sprengel) through 97.8% (C. cunninghamiana Miquel) to 99.1% (C. junghuhniana Miquel). Fifty-five C. equisetifolia clones widely planted in China were successfully genotyped with a subset of 20 EST-SSRs. These newly developed markers will have a great potential for genetic and breeding applications in Casuarina species and related taxa. 相似文献
996.
A bifunctional cellulase–xylanase of a new Chryseobacterium strain isolated from the dung of a straw‐fed cattle 下载免费PDF全文
Hao Tan Renyun Miao Tianhai Liu Lufang Yang Yumin Yang Chunxiu Chen Jianrong Lei Yuhui Li Jiabei He Qun Sun Weihong Peng Bingcheng Gan Zhongqian Huang 《Microbial biotechnology》2018,11(2):381-398
A new cellulolytic strain of Chryseobacterium genus was screened from the dung of a cattle fed with cereal straw. A putative cellulase gene (cbGH5) belonging to glycoside hydrolase family 5 subfamily 46 (GH5_46) was identified and cloned by degenerate PCR plus genome walking. The CbGH5 protein was overexpressed in Pichia pastoris, purified and characterized. It is the first bifunctional cellulase–xylanase reported in GH5_46 as well as in Chryseobacterium genus. The enzyme showed an endoglucanase activity on carboxymethylcellulose of 3237 μmol min?1 mg?1 at pH 9, 90 °C and a xylanase activity on birchwood xylan of 1793 μmol min?1 mg?1 at pH 8, 90 °C. The activity level and thermophilicity are in the front rank of all the known cellulases and xylanases. Core hydrophobicity had a positive effect on the thermophilicity of this enzyme. When similar quantity of enzymatic activity units was applied on the straws of wheat, rice, corn and oilseed rape, CbGH5 could obtain 3.5–5.0× glucose and 1.2–1.8× xylose than a mixed commercial cellulase plus xylanase of Novozymes. When applied on spent mushroom substrates made from the four straws, CbGH5 could obtain 9.2–15.7× glucose and 3.5–4.3× xylose than the mixed Novozymes cellulase+xylanase. The results suggest that CbGH5 could be a promising candidate for industrial lignocellulosic biomass conversion. 相似文献
997.
Background
Interleukin-35 (IL-35) has recently been identified as an immunosuppressive cytokine that has been used as a potential therapy for chronic inflammatory and autoimmune diseases. However, there remains a paucity of data regarding its potential benefits after integration into mesenchymal stem cells (MSCs).Methods
We used a dextran sulfate sodium (DSS)–induced colitis mice model and treated them with IL-35-MSCs, MSCs or saline. The body weight was recorded daily and inflammatory processes were determined. Cytokine secretion by lamina propria lymphocytes (LPLs) and percentage of regulatory T cells (Tregs) were also measured.Results
The data showed that mice in the two treated groups recovered their body weight more rapidly than mice treated with saline in the later stage of colitis. The colon lengths of IL-35-MSC–treated mice were markedly longer than those in the other two groups and the inflammation reduced significantly. Furthermore, the percentage of Foxp3?+?Tregs increased significantly and the level of proinflammatory cytokines produced by LPLs decreased significantly in the IL-35-MSC–treated group.Discussion
The results demonstrate that IL-35-MSCs could ameliorate ulcerative colitis by down-regulating the expression of pro-inflammatory cytokines. 相似文献998.
Xueqi Gan Ling Zhang Beilei Liu Zhuoli Zhu Yuting He Junsheng Chen Junfei Zhu Haiyang Yu 《Journal of physiology and biochemistry》2018,74(3):395-402
Bone is a dynamic organ, the bone-forming osteoblasts and bone-resorbing osteoclasts form the physiological basis of bone remodeling process. During pathological process of numerous inflammatory diseases, these two aspects are uncoupled and the balance is usually tipped in favor of bone destruction. Evidence suggests that the inflammatory destruction of bone is mainly attributed to oxidative stress and is closely related to mitochondrial dysfunction. The mechanisms underlying osteogenic dysfunction in inflammation still need further investigation. Reactive oxygen species (ROS) is associated with mitochondrial dysfunction and cellular damage. Here, we reported an unexplored role of cyclophilin D (CypD), the major modulator of mitochondrial permeability transition pore (mPTP), and the CypD-mPTP axis in inflammation-induced mitochondrial dysfunction and bone damage. And the protective effects of knocking down CypD by siRNA interference or the addition of cyclosporin A (CsA), an inhibitor of CypD, were evidenced by rescued mitochondrial function and osteogenic function of osteoblast under tumor necrosis factor-α (TNF-α) treatment. These findings provide new insights into the role of CypD-mPTP-dependent mitochondrial pathway in the inflammatory bone injury. The protective effect of CsA or other moleculars affecting the mPTP formation may hold promise as a potential novel therapeutic strategy for inflammation-induced bone damage via mitochondrial pathways. 相似文献
999.
Seong-In Na Yeong Ouk Kim Seok-Hwan Yoon Sung-min Ha Inwoo Baek Jongsik Chun 《Journal of microbiology (Seoul, Korea)》2018,56(4):280-285
Genome-based phylogeny plays a central role in the future taxonomy and phylogenetics of Bacteria and Archaea by replacing 16S rRNA gene phylogeny. The concatenated core gene alignments are frequently used for such a purpose. The bacterial core genes are defined as single-copy, homologous genes that are present in most of the known bacterial species. There have been several studies describing such a gene set, but the number of species considered was rather small. Here we present the up-to-date bacterial core gene set, named UBCG, and software suites to accommodate necessary steps to generate and evaluate phylogenetic trees. The method was successfully used to infer phylogenomic relationship of Escherichia and related taxa and can be used for the set of genomes at any taxonomic ranks of Bacteria. The UBCG pipeline and file viewer are freely available at https://www.ezbiocloud.net/tools/ubcg and https://www.ezbiocloud.net/tools/ubcg_viewer, respectively. 相似文献
1000.
Yang Liu Sheng Lu Feng Liu Changwei Shao Qian Zhou Na Wang Yangzhen Li Yingming Yang Yingping Zhang Hejun Sun Weiwei Zheng Songlin Chen 《Marine biotechnology (New York, N.Y.)》2018,20(5):559-565
The Japanese flounder is one of the most widely farmed economic flatfish species throughout eastern Asia including China, Korea, and Japan. Edwardsiella tarda is a major species of pathogenic bacteria that causes ascites disease and, consequently, a huge economy loss for Japanese flounder farming. After generation selection, traditional breeding methods can hardly improve the E. tarda resistance effectively. Genomic selection is an effective way to predict the breeding potential of parents and has rarely been used in aquatic breeding. In this study, we chose 931 individuals from 90 families, challenged by E. tarda from 2013 to 2015 as a reference population and 71 parents of these families as selection candidates. 1,934,475 markers were detected via genome sequencing and applied in this study. Two different methods, BayesCπ and GBLUP, were used for genomic prediction. In the reference population, two methods led to the same accuracy (0.946) and Pearson’s correlation results between phenotype and genomic estimated breeding value (GEBV) of BayesCπ and GBLUP were 0.912 and 0.761, respectively. In selection candidates, GEBVs from two methods were highly similar (0.980). A comparison of GEBV with the survival rate of families that were structured by selection candidates showed correlations of 0.662 and 0.665, respectively. This study established a genomic selection method for the Japanese flounder and for the first time applied this to E. tarda resistance breeding. 相似文献