全文获取类型
收费全文 | 2012篇 |
免费 | 153篇 |
国内免费 | 3篇 |
专业分类
2168篇 |
出版年
2024年 | 2篇 |
2023年 | 26篇 |
2022年 | 28篇 |
2021年 | 60篇 |
2020年 | 30篇 |
2019年 | 47篇 |
2018年 | 66篇 |
2017年 | 51篇 |
2016年 | 81篇 |
2015年 | 87篇 |
2014年 | 112篇 |
2013年 | 163篇 |
2012年 | 175篇 |
2011年 | 156篇 |
2010年 | 102篇 |
2009年 | 91篇 |
2008年 | 125篇 |
2007年 | 123篇 |
2006年 | 105篇 |
2005年 | 72篇 |
2004年 | 69篇 |
2003年 | 70篇 |
2002年 | 64篇 |
2001年 | 31篇 |
2000年 | 32篇 |
1999年 | 29篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1965年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有2168条查询结果,搜索用时 15 毫秒
61.
Dong W. Choi Young S. Do Corbin J. Zea Marcus T. McEllistrem Sung-W. Lee Jeremy D. Semrau Nicola L. Pohl Clint J. Kisting Lori L. Scardino Scott C. Hartsel Eric S. Boyd Gill G. Geesey Theran P. Riedel Peter H. Shafe Kim A. Kranski John R. Tritsch William E. Antholine Alan A. DiSpirito 《Journal of inorganic biochemistry》2006,100(12):2150
Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ. 相似文献
62.
Mannan components of C. albicans (5 mg/kg, i.p.) and S. cerevisiae (2.5 mg/kg, i.p.) cell walls produced pyrogenic responses which were completely inhibited by indomethacin (5 mg/kg, s.c.) pretreatment in rats. A non-selective NOS inhibitor, L-NAME (10 mg/kg, s.c.), also inhibited the pyrogenic effectiveness of C. albicans mannan, whereas it was ineffective on the fever induced by S. cerevisiae mannan. A selective elevation in the serum TNF-alpha levels was observed at the initial phase of the fever due to S. cerevisiae mannan, whereas there was no significant change on the serum levels of TNF-alpha, IL-1beta and IFN-gamma during the latent period or at the initial phase of the fever induced by C. albicans mannan. Injections of N-linked and/or O-linked oligomannosides of the either mannan did not cause any significant change in the body temperature and serum cytokine levels. These data suggest that the mannan components of C. albicans and S. cerevisiae cell walls produce a prostaglandin-dependent fever in rats. The initial signal for fever seems to be different for each mannan. Data also indicate that integrity of the mannans is necessary for the pyrogenic response. 相似文献
63.
Dinh Chuong Nguyen Duy Thanh Tran Thi Luu Luyen Doan Do Hwan Kim Nam Hoon Kim Joong Hee Lee 《Liver Transplantation》2020,10(8)
A novel hybrid of small core@shell structured CoSx@Cu2MoS4 uniformly hybridizing with a molybdenum dichalcogenide/N,S‐codoped graphene hetero‐network (CoSx@Cu2MoS4‐MoS2/NSG) is prepared by a facile route. It shows excellent performance toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The hybrid exhibits rapid kinetics for ORR with high electron transfer number of ≈3.97 and exciting durability superior to commercial Pt/C. It also demonstrates great potential with remarkable stability for HER and OER, requiring low overpotential of 118.1 and 351.4 mV, respectively, to reach a current density of 10 mA cm?2. An electrolyzer based on CoSx@Cu2MoS4‐MoS2/NSG produces low cell voltage of 1.60 V and long‐term stability, surpassing a device of Pt/C + RuO2/C. In addition, a Zn‐air battery using cathodic CoSx@Cu2MoS4‐MoS2/NSG catalyst delivers a high cell voltage of ≈1.44 V and a power density of 40 mW cm?2 at 58 mA cm?2, better than the state‐of‐the‐art Pt/C catalyst. These achievements are due to the rational combination of highly active core@shell CoSx@Cu2MoS4 with large‐area and high‐porosity MoS2/NSG to produce unique physicochemical properties with multi‐integrated active centers and synergistic effects. The outperformances of such catalyst suggest an advanced candidate for multielectrocatalysis applications in metal‐air batteries and hydrogen production. 相似文献
64.
Leehyeon Kim Jiwon Heo Do Hoon Kwon Jin Seok Shin Se Hwan Jang ZeeYong Park Hyun Kyu Song 《Protein science : a publication of the Protein Society》2021,30(3):700
The N‐degron pathway determines the half‐life of proteins in both prokaryotes and eukaryotes by precisely recognizing the N‐terminal residue (N‐degron) of substrates. ClpS proteins from bacteria bind to substrates containing hydrophobic N‐degrons (Leu, Phe, Tyr, and Trp) and deliver them to the caseinolytic protease system ClpAP. This mechanism is preserved in organelles such as mitochondria and chloroplasts. Bacterial ClpS adaptors bind preferentially to Leu and Phe N‐degrons; however, ClpS1 from Arabidopsis thaliana (AtClpS1) shows a difference in that it binds strongly to Phe and Trp N‐degrons and only weakly to Leu. This difference in behavior cannot be explained without structural information due to the high sequence homology between bacterial and plant ClpS proteins. Here, we report the structure of AtClpS1 at 2.0 Å resolution in the presence of a bound N‐degron. The key determinants for α‐amino group recognition are conserved among all ClpS proteins, but the α3‐helix of eukaryotic AtClpS1 is significantly shortened, and consequently, a loop forming a pocket for the N‐degron is moved slightly outward to enlarge the pocket. In addition, amino acid replacement from Val to Ala causes a reduction in hydrophobic interactions with Leu N‐degron. A combination of the fine‐tuned hydrophobic residues in the pocket and the basic gatekeeper at the entrance of the pocket controls the N‐degron selectivity of the plant ClpS protein. 相似文献
65.
Do T Ho F Heidecker B Witte K Chang L Lerner L 《Protein expression and purification》2008,60(2):147-150
Biolayer interferometry is a novel method for quantifying macromolecules, such as proteins, in solution. The presence of other, non-binding molecules does not interfere with quantification, which allows one to measure the concentration of the molecule of interest in a crude mixture. Here we apply this method to determining the dynamic binding capacity of affinity resins. 相似文献
66.
Le MT Wertheim HF Nguyen HD Taylor W Hoang PV Vuong CD Nguyen HL Nguyen HH Nguyen TQ Nguyen TV Van TD Ngoc BT Bui TN Nguyen BG Nguyen LT Luong ST Phan PH Pham HV Nguyen T Fox A Nguyen CV Do HQ Crusat M Farrar J Nguyen HT de Jong MD Horby P 《PloS one》2008,3(10):e3339
Background
Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.Methods and Findings
Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.Conclusion
In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended. 相似文献67.
Kang S Kim EY Bahn YJ Chung JW Lee do H Park SG Yoon TS Park BC Bae KH 《Cellular & molecular biology letters》2007,12(1):139-147
Oxidative stress has been implicated in the pathogenesis of neuronal degenerative diseases. It is also widely known that oxidative
stress induces mitogen-activated protein kinase (MAPK) signaling cascades. In this study, we used proteomic analysis to investigate
the role of the MAPK pathway in oxidative stress-induced neuronal cell death. The results demonstrated that several proteins,
including eukaryotic translation elongation factor 2 (eEF2) and enolase I, showed a differential expression pattern during
the neuronal cell death process, and this was MAPK pathway dependent. Several chaperone and cytoskeletal proteins including
heat shock protein 70, calreticulin, vimentin, prolyl 4-hydroxylase β polypeptide, and transgelin 2 were up-or down-regulated,
despite their expressions not depending on the MAPK pathway. These findings strongly suggest that the expressions of proteins
which play protective roles are independent of the MAPK pathway. On the other hand, eEF2 and enolase I may be the downstream
targets of the MAPK pathway. 相似文献
68.
Joseph K. Cheng Amanda M. Lewis Do Soon Kim Timothy Dyess Hal S. Alper 《Biotechnology journal》2016,11(8):1100-1109
Mammalian cell line development requires streamlined methodologies that will reduce both the cost and time to identify candidate cell lines. Improvements in site‐specific genomic editing techniques can result in flexible, predictable, and robust cell line engineering. However, an outstanding question in the field is the specific site of integration. Here, we seek to identify productive loci within the human genome that will result in stable, high expression of heterologous DNA. Using an unbiased, random integration approach and a green fluorescent reporter construct, we identify ten single‐integrant, recombinant human cell lines that exhibit stable, high‐level expression. From these cell lines, eight unique corresponding integration loci were identified. These loci are concentrated in non‐protein coding regions or intronic regions of protein coding genes. Expression mapping of the surrounding genes reveals minimal disruption of endogenous gene expression. Finally, we demonstrate that targeted de novo integration at one of the identified loci, the 12th exon‐intron region of the GRIK1 gene on chromosome 21, results in superior expression and stability compared to the standard, illegitimate integration approach at levels approaching 4‐fold. The information identified here along with recent advances in site‐specific genomic editing techniques can lead to expedited cell line development. 相似文献
69.
Exon 9 skipping of apoptotic caspase-2 pre-mRNA is promoted by SRSF3 through interaction with exon 8
Ha Na Jang Minho Lee Tiing Jen Loh Seung-Woo Choi Hyun Kyung Oh Heegyum Moon Sunghee Cho Seong-Eui Hong Do Han Kim Zhi Sheng Michael R. Green Daeho Park Xuexiu Zheng Haihong Shen 《Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms》2014,1839(1):25-32
Alternative splicing plays an important role in gene expression by producing different proteins from a gene. Caspase-2 pre-mRNA produces anti-apoptotic Casp-2S and pro-apoptotic Casp-2L proteins through exon 9 inclusion or skipping. However, the molecular mechanisms of exon 9 splicing are not well understood. Here we show that knockdown of SRSF3 (also known as SRp20) with siRNA induced significant increase of endogenous exon 9 inclusion. In addition, overexpression of SRSF3 promoted exon 9 skipping. Thus we conclude that SRSF3 promotes exon 9 skipping. In order to understand the functional target of SRSF3 on caspase-2 pre-mRNA, we performed substitution and deletion mutagenesis on the potential SRSF3 binding sites that were predicted from previous reports. We demonstrate that substitution mutagenesis of the potential SRSF3 binding site on exon 8 severely disrupted the effects of SRSF3 on exon 9 skipping. Furthermore, with the approach of RNA pulldown and immunoblotting analysis we show that SRSF3 interacts with the potential SRSF3 binding RNA sequence on exon 8 but not with the mutant RNA sequence. In addition, we show that a deletion of 26 nt RNA from 5′ end of exon 8, a 33 nt RNA from 3′ end of exon 10 and a 2225 nt RNA from intron 9 did not compromise the function of SRSF3 on exon 9 splicing. Therefore we conclude that SRSF3 promotes exon 9 skipping of caspase-2 pre-mRNA by interacting with exon 8. Our results reveal a novel mechanism of caspase-2 pre-mRNA splicing. 相似文献
70.
Hye-Rim Lee Han-Jun Kim Ji-Seung Ko Yong-Suk Choi Myun-Whan Ahn Sukyoung Kim Sun Hee Do 《PloS one》2013,8(12)
Porous calcium phosphate ceramics are used in orthopedic and craniofacial applications to treat bone loss, or in dental applications to replace missing teeth. The implantation of these materials, however, does not induce stem cell differentiation, so suitable additional materials such as porous calcium phosphate discs are needed to influence physicochemical responses or structural changes. Rabbit adipose-derived stem cells (ADSC) and mouse osteoblastic cells (MC3T3-E1) were evaluated in vitro by the MTT assay, semi-quantitative RT-PCR, and immunoblotting using cells cultured in medium supplemented with extracts from bioceramics, including calcium metaphosphate (CMP), hydroxyapatite (HA) and collagen-grafted HA (HA-col). In vivo evaluation of the bone forming capacity of these bioceramics in rat models using femur defects and intramuscular implants for 12 weeks was performed. Histological analysis showed that newly formed stromal-rich tissues were observed in all the implanted regions and that the implants showed positive immunoreaction against type I collagen and alkaline phosphatase (ALP). The intramuscular implant region, in particular, showed strong positive immunoreactivity for both type I collagen and ALP, which was further confirmed by mRNA expression and immunoblotting results, indicating that each bioceramic material enhanced osteogenesis stimulation. These results support our hypothesis that smart bioceramics can induce osteoconduction and osteoinduction in vivo, although mature bone formation, including lacunae, osteocytes, and mineralization, was not prominent until 12 weeks after implantation. 相似文献