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991.
AIMS: Characterization of a mutated Geobacillus stearothermophilus L-arabinose isomerase used to increase the production rate of D-tagatose. METHODS AND RESULTS: A mutated gene was obtained by an error-prone polymerase chain reaction using L-arabinose isomerase gene from G. stearothermophilus as a template and the gene was expressed in Escherichia coli. The expressed mutated L-arabinose isomerase exhibited the change of three amino acids (Met322-->Val, Ser393-->Thr, and Val408-->Ala), compared with the wild-type enzyme and was then purified to homogeneity. The mutated enzyme had a maximum galactose isomerization activity at pH 8.0, 65 degrees C, and 1.0 mM Co2+, while the wild-type enzyme had a maximum activity at pH 8.0, 60 degrees C, and 1.0-mM Mn2+. The mutated L-arabinose isomerase exhibited increases in D-galactose isomerization activity, optimum temperature, catalytic efficiency (kcat/Km) for D-galactose, and the production rate of D-tagatose from D-galactose. CONCLUSIONS: The mutated L-arabinose isomerase from G. stearothermophilus is valuable for the commercial production of D-tagatose. SIGNIFICANCE AND IMPACT OF THE STUDY: This work contributes knowledge on the characterization of a mutated L-arabinose isomerase, and allows an increased production rate for D-tagatose from D-galactose using the mutated enzyme. 相似文献
992.
Vemanna S. Ramu Akashata Dawane Seonghee Lee Sunhee Oh Hee-Kyung Lee Liang Sun Muthappa Senthil-Kumar Kirankumar S. Mysore 《Molecular Plant Pathology》2020,21(11):1481-1494
Ribosomes play an integral part in plant growth, development, and defence responses. We report here the role of ribosomal protein large (RPL) subunit QM/RPL10 in nonhost disease resistance. The RPL10-silenced Nicotiana benthamiana plants showed compromised disease resistance against nonhost pathogen Pseudomonas syringae pv. tomato T1. The RNA-sequencing analysis revealed that many genes involved in defence and protein translation mechanisms were differentially affected due to silencing of NbRPL10. Arabidopsis AtRPL10 RNAi and rpl10 mutant lines showed compromised nonhost disease resistance to P. syringae pv. tomato T1 and P. syringae pv. tabaci. Overexpression of AtRPL10A in Arabidopsis resulted in reduced susceptibility against host pathogen P. syringae pv. tomato DC3000. RPL10 interacts with the RNA recognition motif protein and ribosomal proteins RPL30, RPL23, and RPS30 in the yeast two-hybrid assay. Silencing or mutants of genes encoding these RPL10-interacting proteins in N. benthamiana or Arabidopsis, respectively, also showed compromised disease resistance to nonhost pathogens. These results suggest that QM/RPL10 positively regulates the defence and translation-associated genes during nonhost pathogen infection. 相似文献
993.
Cho YJ Choi JK Kim JH Lim YS Ham JS Kang DK Chun J Paik HD Kim GB 《Journal of bacteriology》2011,193(18):5021-5022
The draft genome sequence of Lactobacillus salivarius GJ-24 isolated from the feces of healthy adults was determined. Its properties, including milk fermentation activity and bacteriocin production, suggest its potential uses as a probiotic lactic acid bacterium and start culture for dairy products. 相似文献
994.
Bactericidal Activity of Glycinecin A, a Bacteriocin Derived from Xanthomonas campestris pv. glycines, on Phytopathogenic Xanthomonas campestris pv. vesicatoria Cells 下载免费PDF全文
Huy Thang Pham Key Zoung Riu Kong Man Jang Somi K. Cho Moonjae Cho 《Applied microbiology》2004,70(8):4486-4490
The ability of glycinecin A, a bacteriocin derived from Xanthomonas campestris pv. glycines 8ra, to kill closely related bacteria has been demonstrated previously by our group (S. G. Heu et al., Appl. Environ. Microbiol. 67:4105-4110, 2001). In the present study, we aimed at determining the glycinecin A-induced cause of death. Treatment with glycinecin A caused slow dissipation of membrane potential and rapid depletion of the pH gradient. Glycinecin A treatment also induced leakage of potassium ions from X. campestris pv. vesicatoria YK93-4 cells and killed sensitive bacterial cells in a dose-dependent manner. Sensitive cells were killed within 2 h of incubation, most likely due to the potassium ion efflux caused by glycinecin A. These results suggest that the bactericidal mechanism of action of glycinecin A is correlated with the permeability of membranes to hydroxyl and potassium ions, leading to the lethal activity of the bacteriocin on the target bacteria. 相似文献
995.
Genome analysis of a hyper acetone‐butanol‐ethanol (ABE) producing Clostridium acetobutylicum BKM19 下载免费PDF全文
Changhee Cho Donghui Choe Yu‐Sin Jang Kyung‐Jin Kim Won Jun Kim Byung‐Kwan Cho E. Terry Papoutsakis George N. Bennett Do Young Seung Sang Yup Lee 《Biotechnology journal》2017,12(2)
Previously the development of a hyper acetone‐butanol‐ethanol (ABE) producing Clostridium acetobutylicum BKM19 strain capable of producing 30.5% more total solvent by random mutagenesis of its parental strain PJC4BK, which is a buk mutant C. acetobutylicum ATCC 824 strain is reported. Here, BKM19 and PJC4BK strains are re‐sequenced by a high‐throughput sequencing technique to understand the mutations responsible for enhanced solvent production. In comparison with the C. acetobutylicum PJC4BK, 13 single nucleotide variants (SNVs), one deletion and one back mutation SNV are identified in the C. acetobutylicum BKM19 genome. Except for one SNV found in the megaplasmid, all mutations are found in the chromosome of BKM19. Among them, a mutation in the thlA gene encoding thiolase is further studied with respect to enzyme activity and butanol production. The mutant thiolase (thlAV5A) is showed a 32% higher activity than that of the wild‐type thiolase (thlAWT). In batch fermentation, butanol production is increased by 26% and 23% when the thlAV5A gene is overexpressed in the wild‐type C. acetobutylicum ATCC 824 and in its derivative, the thlA‐knockdown TKW‐A strain, respectively. Based on structural analysis, the mutation in thiolase does not have a direct effect on the regulatory determinant region (RDR). However, the mutation at the 5th residue seems to influence the stability of the RDR, and thus, increases the enzymatic activity and enhances solvent production in the BKM19 strain. 相似文献
996.
997.
Eun-Jin Kim Hyung Won Ryu Marcus J. Curtis-Long Jaehee Han Jun Young Kim Jung Keun Cho Dawon Kang Ki Hun Park 《Bioorganic & medicinal chemistry letters》2010,20(14):4237-4239
Although it has not been extensively studied, a significant volume of literature suggests that TREK2 will probably turn out to be an important channel in charge of tuning neuronal transmitter and hormone levels. Thus, pharmacological tools which can manipulate this channel, such as selective agonists are essential both in drug design and to further our understanding of this system. Our investigations have shown that sulfonate (‘O’) chalcone and sulfonamide (‘N’) chalcones regulate the TREK2 channel in remarkably different ways: sulfonamide chalcone 5 behaved as an inhibitor with an IC50 of 62 μM, whereas the sulfonate analogue 11 activated TREK2 with EC50 value of 167 μM. 相似文献
998.
Park HG Choi JY Choi SH Park MK Lee J Suh YG Cho H Oh U Kim HD Joo YH Kim SY Park YH Jeong YS Choi JK Kim JK Jew SS 《Bioorganic & medicinal chemistry letters》2004,14(7):1693-1696
A series of N-4-methansulfonamidobenzyl-N'-2-substituted-4-tert-butylbenzyl thioureas were prepared for the study of their agonistic/antagonistic activities to the vanilloid receptor in rat DRG neurons. Their structure-activity relationship reveals that there is a space for another hydrophobic binding interaction around 2-position in 4-tert-butylbenzyl region. Among the prepared derivatives, 6n show the highest antagonistic activity against the vanilloid receptor (IC(50)=15 nM). 相似文献
999.
Koo NY Li J Hwang SM Choi SY Lee SJ Oh SB Kim JS Lee JH Park K 《Biochemical and biophysical research communications》2006,342(4):1114-1122
We recently found that the concentration of HCO3- in guinea-pig saliva is very similar to that of human saliva; however, the entity that regulates HCO3- transport has not yet been fully characterized. In order to investigate the mechanism of HCO3- transport, we identified, cloned, and characterized a sodium bicarbonate (Na(+)/HCO3- cotransporter found in guinea-pig parotid glands (gpNBC1). The gpNBC1 gene encodes a 1079-amino acid protein that has 95% and 96% homology with human and mouse parotid NBC1, respectively. Oocytes expressing gpNBC1 were exposed to HCO3- or Na(+)-free solutions, which resulted in a marked change in membrane potentials (V(m)), suggesting that gpNBC1 is electrogenic. Likewise, a gpNBC1-mediated pH recovery was observed in gpNBC1 transfected human hepatoma cells; however, in the presence of 4, 4-diisothiocyanostilbene-2,2-disulfonic acid, a specific NBC1 inhibitor, such changes in V(m) and pH(i) were not observed. Together, the data show that the cloned guinea-pig gene is a functional, as well as sequence homologue of human NBC1. 相似文献
1000.
An HJ Lee HJ Jun SH Hwang SY Kim BC Kim K Lee KM Oh MK Kim J 《Bioprocess and biosystems engineering》2011,34(7):841-847
Lipase (LP) was immobilized on electrospun and ethanol-dispersed polystyrene–poly(styrene-co-maleic anhydride) (PS–PSMA) nanofibers
(EtOH-NF) in the form of enzyme precipitate coatings (EPCs). LP precipitate coatings (EPCs-LP) were prepared in a three-step
process, consisting of covalent attachment, LP precipitation, and crosslinking of precipitated LPs onto the covalently attached
LPs via glutaraldehyde treatment. The LP precipitation was performed by adding various concentrations of ammonium sulfate
(20–50%, w/v). EPCs-LP improved the LP activity and stability when compared to covalently attached LPs (CA-LP) and the enzyme
coatings of LPs (EC-LP) without the LP precipitation. For example, the use of 40% (w/v) ammonium sulfate resulted in EPC40-LP
with the highest activity, which was 4.0 and 3.6 times higher than those of CA-LP and EC-LP, respectively. After 165-day incubation
under rigorous shaking at 200 rpm, the residual activities of EPC50-LP were 0.5 μM/min mg of EtOH-NF, representing 113 and
75 times higher than those of CA-LP and EC-LP, respectively. When LP was partially purified via a simple ammonium sulfate
precipitation and dialysis, both activities and stabilities of EC-LP and EPC-LP could be marginally improved. It is anticipated
that the improved LP activity and stability in the form of EPCs would allow for their potential applications in various bioconversion
processes such as biodiesel production and ibuprofen resolution. 相似文献