全文获取类型
收费全文 | 4908篇 |
免费 | 301篇 |
国内免费 | 2篇 |
出版年
2024年 | 6篇 |
2023年 | 13篇 |
2022年 | 67篇 |
2021年 | 80篇 |
2020年 | 52篇 |
2019年 | 71篇 |
2018年 | 100篇 |
2017年 | 86篇 |
2016年 | 156篇 |
2015年 | 263篇 |
2014年 | 316篇 |
2013年 | 334篇 |
2012年 | 484篇 |
2011年 | 424篇 |
2010年 | 268篇 |
2009年 | 240篇 |
2008年 | 336篇 |
2007年 | 263篇 |
2006年 | 257篇 |
2005年 | 220篇 |
2004年 | 190篇 |
2003年 | 169篇 |
2002年 | 148篇 |
2001年 | 127篇 |
2000年 | 124篇 |
1999年 | 112篇 |
1998年 | 38篇 |
1997年 | 28篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 26篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1969年 | 4篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有5211条查询结果,搜索用时 31 毫秒
991.
Kangmin Kim Ye-Jin Jang Sang-Myeong Lee Byung-Taek Oh Jong-Chan Chae Kui-Jae Lee 《Molecules and cells》2014,37(2):109-117
Microbiota in the niches of the rhizosphere zones can affect plant growth and responses to environmental stress conditions via mutualistic interactions with host plants. Specifically, some beneficial bacteria, collectively referred to as Plant Growth Promoting Rhizobacteria (PGPRs), increase plant biomass and innate immunity potential. Here, we report that Enterobacter sp. EJ01, a bacterium isolated from sea china pink (Dianthus japonicus thunb) in reclaimed land of Gyehwa-do in Korea, improved the vegetative growth and alleviated salt stress in tomato and Arabidopsis. EJ01 was capable of producing 1-aminocy-clopropane-1-carboxylate (ACC) deaminase and also exhibited indole-3-acetic acid (IAA) production. The isolate EJ01 conferred increases in fresh weight, dry weight, and plant height of tomato and Arabidopsis under both normal and high salinity conditions. At the molecular level, short-term treatment with EJ01 increased the expression of salt stress responsive genes such as DREB2b, RD29A, RD29B, and RAB18 in Arabidopsis. The expression of proline biosynthetic genes (i.e. P5CS1 and P5CS2) and of genes related to priming processes (i.e. MPK3 and MPK6) were also up-regulated. In addition, reactive oxygen species scavenging activities were enhanced in tomatoes treated with EJ01 in stressed conditions. GFP-tagged EJ01 displayed colonization in the rhizosphere and endosphere in the roots of Arabidopsis. In conclusion, the newly isolated Enterobacter sp. EJ01 is a likely PGPR and alleviates salt stress in host plants through multiple mechanisms, including the rapid up-regulation of conserved plant salt stress responsive signaling pathways. 相似文献
992.
Su-Jin Oh Kyung-Ho Lee Ho-Cheol Kim Christy Catherine Hyungdon Yun Dong-Myung Kim 《Biotechnology and Bioprocess Engineering》2014,19(3):426-432
Nature uses 20 canonical amino acids as the standard building blocks of proteins; however, the incorporation of unnatural amino acids (Uaas) can endow polypeptide sequences with new structural and functional features. Although aminoacyl-tRNA synthetases (aaRSs) can accept an array of Uaas in place of their natural counterparts, Uaas generally are charged to tRNAs with substantially lower efficiencies. This particularly makes it difficult to incorporate multiple Uaas into a protein sequence. In this study, we discuss the use of a cell-free protein synthesis system as a versatile platform for the efficient incorporation of multiple Uaas into proteins. Taking advantage of the open nature of cell-free protein synthesis that allows flexible manipulation of its ingredients, we explored the application of Uaas in 10 mM range of concentrations to kinetically overcome the low affinity of aaRSs towards unnatural amino acids. Supplementation of recombinant aaRSs was also investigated to further increase the Uaa-tRNA pools. As a result, under the modified reaction conditions, as many as five different Uaas could be incorporated into a single protein without compromising the yield of protein synthesis. 相似文献
993.
Jisun Paeng Jae Hyun Chang Sun Ha Lee Bo Young Nam Hye-Young Kang Seonghun Kim Hyung Jung Oh Jung Tak Park Seung Hyeok Han Tae-Hyun Yoo Shin-Wook Kang 《Apoptosis : an international journal on programmed cell death》2014,19(12):1678-1690
Glycogen synthase kinase-3β (GSK-3β) is involved in the pathogenesis of various kidney diseases. This study was undertaken to examine the changes in GSK-3β activity in podocytes under diabetic conditions and to elucidate the functional role of GSK-3β in podocyte apoptosis. In vivo, 32 rats were injected with either diluent (n = 16, C) or with streptozotocin intraperitoneally (n = 16, DM), and 8 rats from each group were treated with 6-bromoindirubin-3′-oxime (BIO) for 3 months. In vitro, immortalized mouse podocytes were exposed to 5.6 mM glucose or 30 mM glucose (HG) with or without 10 μM BIO. Western blot analysis and TUNEL or Hoechst 33342 staining were performed to identify apoptosis. Urinary albumin excretion was significantly higher in DM rats, and this increase was significantly abrogated in DM rats by BIO treatment. The protein expression of Tyr216-phospho-GSK-3β was significantly increased in DM glomeruli and in cultured podocytes exposed to HG. Western blot analysis revealed that the protein expression of Bax and active fragments of caspase-3 were significantly increased, whereas phospho-Akt, β-catenin, and Bcl-2 protein expression were significantly decreased in DM glomeruli and HG-stimulated podocytes. Apoptosis, determined by TUNEL assay and Hoechst 33342 staining, was also significantly increased in podocytes under diabetic conditions. The changes in the expression of apoptosis-related molecules and the increase in the number of apoptotic cells in DM glomeruli as well as in HG-stimulated podocytes were significantly ameliorated by BIO. These findings suggest that enhanced GSK-3β activity within podocytes under diabetic conditions is associated with podocyte loss in diabetic nephropathy. 相似文献
994.
995.
Dong-Joo You Cho Rong Park Hyun Bok Lee Mi Jin Moon Ju-Hee Kang Cheolju Lee Seong-Hyun Oh Curie Ahn Jae Young Seong Jong-Ik Hwang 《The Journal of biological chemistry》2014,289(25):17709-17720
IKKβ functions as a principal upstream activator of the canonical NF-κB pathway by phosphorylating IκB, leading to its proteasomal degradation. Because IKKβ is considered a therapeutic target, understanding its regulation may facilitate the design of efficient regulators of this molecule. Here, we report a novel IKKβ-interacting molecule, NME1L, a splicing variant of the NME1 protein. NME1 has attracted attention in cancer research because of its antimetastatic activity and reduced expression in multiple aggressive types of cancer. However, the effect was just moderate but not dramatic in anti-cancer activities. We found that only NME1L interacts with IKKβ. Exogenous expression of NME1L resulted in a potent decrease in TNFα-stimulated NF-κB activation, whereas knockdown of NME1/NME1L with shRNA enhanced activity of NF-κB. NME1L down-regulates IKKβ signaling by blocking IKKβ-mediated IκB degradation. When NME1L was introduced into highly metastatic HT1080 cells, the mobility was efficiently inhibited. Furthermore, in a metastasis assay, NME1L-expressing cells did not colonize the lung. Based on these results, NME1L is a potent antimetastatic protein and may be a useful weapon in the fight against cancers. 相似文献
996.
Heesung Chung Hyejung Jung Jung-hyun Lee Hye Yun Oh Ok Bin Kim Inn-Oc Han Eok-Soo Oh 《The Journal of biological chemistry》2014,289(31):21751-21759
Melanocytes, which produce the pigment melanin, are known to be closely regulated by neighboring keratinocytes. However, how keratinocytes regulate melanin production is unclear. Here we report that melanin production in melanoma cells (B16F10 and MNT-1) was increased markedly on a keratinocyte-derived extracellular matrix compared with a melanoma cell-derived extracellular matrix. siRNA-mediated reduction of keratinocyte-derived laminin-332 expression decreased melanin synthesis in melanoma cells, and laminin-332, but not fibronectin, enhanced melanin content and α-melanocyte-stimulating hormone-regulated melanin production in melanoma cells. Similar effects were observed in human melanocytes. Interestingly, however, laminin-332 did not affect the expression or activity of tyrosinase. Instead, laminin-332 promoted the uptake of extracellular tyrosine and, subsequently, increased intracellular levels of tyrosine in both melanocytes and melanoma cells. Taken together, these data strongly suggest that keratinocyte-derived laminin-332 contributes to melanin production by regulating tyrosine uptake. 相似文献
997.
Juntaek Oh Eunhye Goo Ingyu Hwang Sangkee Rhee 《The Journal of biological chemistry》2014,289(16):11465-11475
The Burkholderia species utilize acetyl-CoA and oxaloacetate, substrates for citrate synthase in the TCA cycle, to produce oxalic acid in response to bacterial cell to cell communication, called quorum sensing. Quorum sensing-mediated oxalogenesis via a sequential reaction by ObcA and ObcB counteracts the population-collapsing alkaline pH of the stationary growth phase. Thus, the oxalic acid produced plays an essential role as an excreted public good for survival of the group. Here, we report structural and functional analyses of ObcA, revealing mechanistic features distinct from those of citrate synthase. ObcA exhibits a unique fold, in which a (β/α)8-barrel fold is located in the C-domain with the N-domain inserted into a loop following α1 in the barrel fold. Structural analyses of the complexes with oxaloacetate and with a bisubstrate adduct indicate that each of the oxaloacetate and acetyl-CoA substrates is bound to an independent site near the metal coordination shell in the barrel fold. In catalysis, oxaloacetate serves as a nucleophile by forming an enolate intermediate mediated by Tyr322 as a general base, which then attacks the thioester carbonyl carbon of acetyl-CoA to yield a tetrahedral adduct between the two substrates. Therefore, ObcA catalyzes its reaction by combining the enolase and acetyltransferase superfamilies, but the presence of the metal coordination shell and the absence of general acid(s) produces an unusual tetrahedral CoA adduct as a stable product. These results provide the structural basis for understanding the first step in oxalogenesis and constitute an example of the functional diversity of an enzyme for survival and adaptation in the environment. 相似文献
998.
999.
Hyung-Jin Park Sang-Eun Lee Won-Ja Lee Jung-Hyun Oh Easwaran Maheswaran Kyoung-Won Seo Kun-Ho Song 《The Korean journal of parasitology》2014,52(6):691-694
The purpose of this study was to conduct a survey of Dirofilaria immitis infection among stray cats in Korea using nested PCR. We included 235 stray cats (121 females and 114 males) and evaluated each for the presence of feline heartworm infection. Blood samples were collected from 135 cats in Daejeon, 50 cats in Seoul, and 50 cats from Gyeonggi-do (Province). Of the 235 DNA samples, 14 (6.0%) were positive for D. immitis. The prevalence of infection in male cats (8/114, 7.0%) tended to be higher than that in female cats (6/121, 5.0%), but the difference was not statistically significant. In each location, 8, 2, and 4 cats were positive for infection, respectively, based on DNA testing. No significant differences in the prevalence were observed among the geographic regions, although the rate of infection was higher in Gyeonggi-do (8.0%) than Daejeon (5.9%) and Seoul (4.0%). We submitted 7 of the 14 D. immitis DNA-positive samples for sequencing analysis. All samples corresponded to partial D. immitis cytochrome c oxidase subunit I gene sequences with 99% homology to the D. immitis sequence deposited in GenBank (accession no. ). To the best of our knowledge, this is the first survey using nested PCR to analyze the prevalence of D. immitis in stray cats in Korea. FN391553相似文献
1000.
Myong Kim Abhilash Cheeti Changwon Yoo Minsoo Choo Jae-Seung Paick Seung-June Oh 《PloS one》2014,9(11)