全文获取类型
收费全文 | 5460篇 |
免费 | 407篇 |
国内免费 | 9篇 |
出版年
2023年 | 14篇 |
2022年 | 62篇 |
2021年 | 82篇 |
2020年 | 72篇 |
2019年 | 78篇 |
2018年 | 119篇 |
2017年 | 107篇 |
2016年 | 144篇 |
2015年 | 262篇 |
2014年 | 305篇 |
2013年 | 358篇 |
2012年 | 501篇 |
2011年 | 443篇 |
2010年 | 251篇 |
2009年 | 242篇 |
2008年 | 357篇 |
2007年 | 293篇 |
2006年 | 271篇 |
2005年 | 276篇 |
2004年 | 228篇 |
2003年 | 232篇 |
2002年 | 173篇 |
2001年 | 145篇 |
2000年 | 129篇 |
1999年 | 117篇 |
1998年 | 33篇 |
1997年 | 50篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 27篇 |
1993年 | 22篇 |
1992年 | 46篇 |
1991年 | 42篇 |
1990年 | 35篇 |
1989年 | 36篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 26篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 19篇 |
1982年 | 11篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1972年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有5876条查询结果,搜索用时 15 毫秒
91.
Jisub Hwang Chang-Sook Jeong Chang Woo Lee Seung Chul Shin Han-Woo Kim Sung Gu Lee Ui Joung Youn Chang Sup Lee Tae-Jin Oh Hak Jun Kim Hyun Park Hyun Ho Park Jun Hyuck Lee 《Journal of microbiology (Seoul, Korea)》2020,58(7):606-613
Crystal structures of enoyl-coenzyme A (CoA) isomerase from Bosea sp. PAMC 26642 (BoECI) and enoyl-CoA hydratase from Hymenobacter sp. PAMC 26628 (HyECH) were determined at 2.35 and 2.70 Å resolution, respectively. BoECI and HyECH are members of the crotonase superfamily and are enzymes known to be involved in fatty acid degradation. Structurally, these enzymes are highly similar except for the orientation of their C-terminal helix domain. Analytical ultracentrifugation was performed to determine the oligomerization states of BoECI and HyECH revealing they exist as trimers in solution. However, their putative ligand-binding sites and active site residue compositions are dissimilar. Comparative sequence and structural analysis revealed that the active site of BoECI had one glutamate residue (Glu135), this site is occupied by an aspartate in some ECIs, and the active sites of HyECH had two highly conserved glutamate residues (Glu118 and Glu138). Moreover, HyECH possesses a salt bridge interaction between Glu98 and Arg152 near the active site. This interaction may allow the catalytic Glu118 residue to have a specific conformation for the ECH enzyme reaction. This salt bridge interaction is highly conserved in known bacterial ECH structures and ECI enzymes do not have this type of interaction. Collectively, our comparative sequential and structural studies have provided useful information to distinguish and classify two similar bacterial crotonase superfamily enzymes. 相似文献
92.
Woo Yong Sung Ji Won Yu Jong Tae Hwang Hee Jin Nam Ji Ye Park Yongae Kim Jang‐Hee Cho 《Journal of peptide science》2020,26(8)
Antimicrobial peptides are class of small, positively charged peptides known for their broad‐spectrum antimicrobial activity. Antimicrobial activities for most antimicrobial peptides have largely remained elusive, particularly in the lactic acid bacteria. However, recently our investigation using LPcin‐YK3, an antimicrobial peptide from bovine milk, suggests that in vitro antimicrobial activity was reduced over 100‐fold compared with pathogenic bacteria. Additionally, for the structural study of how antimicrobial peptide undergoes its reaction at the proteolytic pathway of lactic acid bacteria based on degradation assay and propidium iodide staining, we performed molecular docking for interaction between oligopeptide‐binding protein A and LPcin‐YK3 peptide. Given that degradation related to the LPcin‐YK3 peptide in lactic acid bacteria proteolytic system, the inhibitory inactivity of LPcin‐YK3 against beneficial lactic acid bacteria strains may be one of the primary pharmacological properties of recombinant peptide discovered in bovine milk. These results provide structural and functional insights into the proteolytic mechanism and possibility as a putative substrate of oligopeptide‐binding protein A in respect of LPcin‐YK3 peptide. 相似文献
93.
On‐site predetection of pathogens could significantly decrease of a disease outbreak or national loss in most of the countries. However, conventional detection techniques are limited in use for on‐site detection due to the necessity of specialized skill or equipment. Therefore, it is necessary to develop a new technique that can predetect pathogens in the field without special skills or equipment. Here, a DNAzyme strategy to control a plasmonic biosensor for rapid and simple visual detection of Salmonella choleraesuis is adopted. Multicomponent DNAzyme formed by target addition can cleave the linker effectively at 50 °C. Linker cleavage induces dispersion of two DNA‐immobilized gold nanoparticles and color change. Under optimized assay conditions, the target could be detected via visual discrimination sensitively and specifically. Moreover, the biosensor shows the possibility of practical use with contaminants and a 16S rRNA real target. As a result, the proposed plasmonic biosensor can visually detect S. choleraesuis without unstable enzymes, a specialized technique, or equipment. Therefore, these advantages could allow that this biosensor would be used for on‐site predetection to lower the risk of transmission of infectious diseases. 相似文献
94.
Takumi Takata Seongmin Ha Tamaki Koide Noriko Fujii 《Protein science : a publication of the Protein Society》2020,29(4):941-951
Recent studies have suggested that the isomerization/racemization of aspartate residues in proteins increases in aged tissues. One such residue is Asp151 in lens‐specific αA‐crystallin. Although many isomerization/racemization sites have been reported in various proteins, the factors that lead to those modifications in proteins in vivo remain obscure. Therefore, an in vitro system is needed to assess the mechanisms of modifications of Asp under various conditions. Deamidation of Asn to Asp in proteins occurs more rapidly than isomerization/racemization of Asp, although the reaction passes through the same intermediate in both pathways. Here, therefore, we replaced Asp151 in human lens αA‐crystallin with Asn by using site‐directed mutagenesis. The recombinant protein was expressed in Escherichia coli and used to investigate the deamidation/isomerization/racemization of Asn151 after incubation at 50°C for various durations and under different pH. After incubation, the mutant αA‐crystallin was subjected to enzymatic digestion followed by liquid chromatography–MS/MS to evaluate the ratio of modifications in Asn151‐containing peptides. The Asp151Asn αA‐crystallin mutant showed rapid deamidation to Asp with the formation of specific Asp isomers. In particular, deamidation increased greatly under basic conditions. By contrast, subunit–subunit interactions between αA‐crystallin and αB‐crystallin had little effect on the modification of Asn151. Our findings suggest that the Asp151Asn αA‐crystallin mutant represents a good in vitro model protein to assess deamidation, isomerization, and the racemization intermediates. Furthermore, our in vitro results show a different trend from in vivo data, implying the presence of specific factors that induce racemization from L‐Asp to D‐Asp residues in vivo. 相似文献
95.
Young Kyu Kim Sang Eun Kim Hyo Chang Park Jeong Ho Hwang Hoon Taek Lee 《Biochemistry and Biophysics Reports》2020
Xenotransplantation has been considered an alternative to the moderate shortage of donor organs for transplantation. To achieve successful xenotransplatation, there is the need to overcome immune rejection. Although, hyperacute rejection has been overcome by α1,3-galactosyltransferase knockout pig, cellular immune rejection remains as a subsequent barrier. Interleukin-10 (IL-10) is known as an anti-inflammatory and immunomodulatory cytokine which has been shown to limit inflammatory responses by inhibiting macrophage activation in several animal experiments. To study the effect of human IL-10 (hIL-10) on pig-to-human xenotransplantation, porcine kidney epithelial cell line (PK(15)) expressing hIL-10 was established. The cytotoxicity of macrophages decreased by hIL-10 from transgenic cells. Furthermore, there is a decreased production of pro-inflammatory cytokines, tumor necrosis factor-α and interleukin-23, and increased anti-inflammatory cytokines like IL-10, but not transforming growth factor beta, in the presence of hIL-10. Also, macrophage polarization toward M2-like phenotype were induced by hIL-10 from transgenic PK(15) cells. Finally, we suggest that the cytotoxicity of human macrophages was reduced by hIL-10 from transgenic cells, inducing M2-like macrophage polarization. Therefore, these results show that hIL-10 transgenic pig can be used as a model to overcome acute immune rejection in pig-to-human xenotransplantation. 相似文献
96.
ABSTRACT Hesperidin, a citrus flavonoid, can exert numerous beneficial effects on human health. Interstitial cells of Cajal (ICC) are pacemaker cells in the gastrointestinal (GI) tract. In the present study, we investigated potential effects of hesperidin on pacemaker potential of ICC in murine small intestine and GI motility. A whole-cell patch-clamp configuration was used to record pacemaker potential in ICC, and GI motility was investigated in vivo by recording gastric emptying (GE) and intestinal transit rate (ITR). Hesperidin depolarized pacemaker potentials of ICC in a dose-dependent manner. Pre-treatment with methoctramine or 4-DAMP did not inhibit hesperidin-induced pacemaker potential depolarization. Neither a 5-HT3 receptor antagonist (Y25130) nor a 5-HT7 receptor antagonist (SB269970) reduced the effect of hesperidin on ICC pacemaker potential, whereas the 5-HT4 receptor antagonist RS39604 was found to inhibit this effect. In the presence of GDP–β–S, hesperidin-induced pacemaker potential depolarization was inhibited. Moreover, in the presence of U73122 and calphostin C, hesperidin did not depolarize pacemaker potentials. Furthermore, hesperidin accelerated GE and ITR in vivo. These results imply that hesperidin depolarized ICC pacemaker potential via 5-HT4 receptors, G protein, and PLC/PKC dependent pathways and that it increased GI motility. Therefore, hesperidin may be a promising novel drug to regulate GI motility. 相似文献
97.
Hood Glen Ray Papuga Shirley A. Socrates Connor Rankin Kennadi Hwang Kyotaek 《Plant and Soil》2021,466(1-2):569-580
Plant and Soil - Tussock microhabitat is a universal phenomenon in wetlands, where soil and plant properties differ from their surrounding lawns. This study aims to investigate the differences of... 相似文献
98.
99.
Chang Man Ha Eun Mi Hwang Eunju Kim Da Yong Lee Sunghoe Chang Byung Ju Lee Seong-Geun Hong Jae-Yong Park 《Molecules and cells》2013,36(6):527-533
Neural epidermal growth factor-like protein-like 2 (NELL2) is a secreted glycoprotein that is predominantly expressed in the nervous system, but little is known about the intracellular movement and secretion mechanism of this protein. By monitoring the localization and movements of enhanced green fluorescent protein (EGFP)-labeled NELL2 in living cultured hippocampal neuroprogenitor HiB5 cells, we determined the subcellular localization of NELL2 and its intracellular movement and secretion mechanism. Cterminal EGFP-fused NELL2 showed a typical expression pattern of secreted proteins, especially with respect to its localization in the endoplasmic reticulum, Golgi apparatus, and punctate structures. Vesicles containing NELL2 exhibited bidirectional movement in HiB5 cells. The majority of the vesicles (70.1%) moved in an anterograde direction with an average velocity of 0.454 μm/s, whereas some vesicles (28.7%) showed retrograde movement with an average velocity of 0.302 μm/s. The movement patterns of NELL2 vesicles were dependent upon the presence of microtubules in HiB5 cells. Anterograde movement of NELL2 did not lead to a detectable accumulation of NELL2 in the peripheral region of the cell, indicating that it was secreted into the culture medium. We also showed that the N-terminal 29 amino acids of NELL2 were important for secretion of this protein. Taken together, these results strongly suggest that the N-terminal region of NELL2 determines both the pattern of its intracellular expression and transport of NELL2 vesicles by high-velocity movement. Therefore, NELL2 may affect the cellular activity of cells in a paracrine or autocrine manner. 相似文献
100.
Sung-Eun Kim Il-Gyu Ko Lakkyong Hwang In-Young Choi Mal-Soon Shin Chang-Ju Kim Khae-Hawn Kim 《Journal of biomedical science》2013,20(1):81