全文获取类型
收费全文 | 590篇 |
免费 | 32篇 |
国内免费 | 1篇 |
出版年
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 19篇 |
2016年 | 15篇 |
2015年 | 31篇 |
2014年 | 44篇 |
2013年 | 42篇 |
2012年 | 65篇 |
2011年 | 59篇 |
2010年 | 36篇 |
2009年 | 25篇 |
2008年 | 32篇 |
2007年 | 24篇 |
2006年 | 30篇 |
2005年 | 27篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有623条查询结果,搜索用时 15 毫秒
161.
In this study, the trypsin gene (bgtryp-1) from the German cockroach, Blattella germanica, was cloned via the immunoscreening of patients with allergies to cockroaches. Nucleotide sequence analysis predicted an 863 bp open reading frame which encodes for 257 amino acids. The deduced amino acid sequence exhibited 42-57% homology with the serine protease from dust mites, and consisted of a conserved catalytic domain (GDSGGPLV). bgtryp-1 was determined by both Northern and Southern analysis to be a 0.9 kb, single-copy gene. SDS-PAGE and Western blotting analyses of the recombinant protein (Bgtryp-1) over-expressed in Escherichia coli revealed that the molecular mass of the expressed protein was 35 kDa, and the expressed protein was capable of reacting with the sera of cockroach allergy patients. We also discussed the possibility that trypsin excreted by the digestive system of the German cockroach not only functions as an allergen, but also may perform a vital role in the activation of PAR-2. 相似文献
162.
Dong Min Kim Sang Jun Lee Suk Kwon Yoon Si Myung Byun 《Biochemical and biophysical research communications》2002,290(1):585-588
Several pathogenic bacteria secrete plasminogen activator proteins. Streptokinase (SKe) produced by Streptococcus equisimilis and staphylokinase secreted from Staphylococcus aureus are human plasminogen activators and streptokinase (SKu), produced by Streptococcus uberis, is a bovine plasminogen activator. Thus, the fusion proteins among these activators can explain the function of each domain of SKe. Replacement of the SKalpha domain with staphylokinase donated the staphylokinase-like activation activity to SKe, and the SKbetagamma domain played a role of nonproteolytic activation of plasminogen. Recombinant SKu also activated human plasminogen by staphylokinase-like activation mode. Because SKu has homology with SKe, the bovine plasminogen activation activities of SKe fragments were checked. SKebetagamma among them had activation activity with bovine plasminogen. This means that the C-terminal domain (gamma-domain) of streptokinase determines plasminogen species necessary for activation and converses the ability of substrate recognition to human species. 相似文献
163.
Yuki Y Byun Y Fujita M Izutani W Suzuki T Udaka S Fujihashi K McGhee JR Kiyono H 《Biotechnology and bioengineering》2001,74(1):62-69
Mucosal administration of experimental autoimmune encephalomyelitis (EAE)-specific autoantigens can reduce the onset of disease. To examine whether cholera toxin-B-subunit (CTB)-conjugated EAE-specific T-cell epitope can reduce development of the autoimmune disease in mice, we produced a recombinant hybrid molecule of CTB fusion protein linked with proteolipid-protein (PLP)-peptide139-151(C140S) at levels up to 0.1 gram per liter culture media in Bacillus brevis as a secretion-expression system. Amino acid sequencing and GM1-receptor binding assay showed that this expression system produced a uniformed recombinant hybrid protein. EAE was induced in SJL/J mice by systemic administration with the PLP-peptide. When nasally immunized 5 times with 70 microg rCTB PLP-peptide hybrid protein, mice showed a significantly suppressed development of ongoing EAE and an inhibition of both the PLP-peptide-specific delayed-type hypersensitivity (DTH) responses and leukocyte infiltration into the spinal cord. In contrast, all mice given the PLP-peptide alone or the PLP-peptide with the free form of CTB did not suppress the development of EAE and DTH responses. These results suggest that nasal treatment with the recombinant B. brevis-derived hybrid protein of CTB and autoantigen peptide could prove useful in the control of multiple sclerosis. 相似文献
164.
A variety of human cell types, including human osteoblasts (hOBs), produce an IGFBP-4 protease, which cleaves IGFBP-4 in the presence of IGF-II. Recently, the pregnancy-associated plasma protein (PAPP)-A has been determined to be the IGF-II-dependent IGFBP-4 protease produced by human fibroblasts. This study sought to define the mechanism by which IGF-II enhances IGFBP-4 proteolysis. Addition of PAPP-A antibody blocked the IGFBP-4 proteolytic activity in hOB conditioned medium (CM), suggesting that PAPP-A is the major IGFBP-4 protease in hOB CM. Pre-incubation of IGFBP-4 with IGF-II, followed by removal of unbound IGF-II, led to IGFBP-4 proteolysis without further requirement of the presence of IGF-II in the reaction. In contrast, prior incubation of the partially purified IGFBP-4 protease from either hOB CM or human pregnancy serum with IGF-II did not lead to IGFBP-4 proteolysis unless IGF-II was re-added to the assays. To further confirm that the interaction between IGF-II and IGFBP-4 is required for IGFBP-4 protease activity, we prepared IGFBP-4 mutants, which contained the intact cleavage site (Met135-Lys136) but lacked the IGF binding activity, by deleting the residues Leu72-His74 in the IGF binding domain or Cys183-Glu237 that contained an IGF binding enhancing motif. The IGFBP-4 protease was unable to cleave these IGFBP-4 mutants, regardless of whether or not IGF-II was present in the assay. Conversely, an IGFBP-4 mutant with His74 replaced by an Ala, which exhibited normal IGF binding activity, was effectively cleaved in the presence of IGF-II. Taken together, these findings provided strong evidence that the interaction between IGF-II and IGFBP-4, rather than the direct interaction between IGF-II and IGFBP-4 protease, is required for optimal IGFBP-4 proteolysis. 相似文献
165.
Eun-Young Song Kyoung-A. Kim Yung-Dai Kim Dur-Han Kwon Hong-Soo Lee Cheorl-Ho Kim Tae-Wha Chung Si Myung Byun 《Biotechnology letters》2000,22(3):201-204
Human N-acetylglucosaminyltransferase-III (GnT-III) has not been hitherto purified from either tissue or cell line. Although rat GnT-III has been purified from rat kidney tissue, the procedure involves laborious and complex steps. We have developed a simplified procedure based on a QAE (diethyl[2-hydroxypropyl]aminoethyl)-Sepharose and an immunoaffinity chromatography technique. The immunoaffinity chromatography utilized a monoclonal antibody to human aglycosyl recombinant N-acetylglucosaminyltransferase-III. With the new procedure, human N-acetylglucosaminyltransferase-III was purified from hepatocellular carcinoma tissues with an increase in the specific enzyme activity of 378-fold. 相似文献
166.
Enhancement of Secretion and Extracellular Stability of Staphylokinase in Bacillus subtilis by wprA Gene Disruption
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sang Jun Lee Dong Min Kim Kwang Hee Bae Si Myung Byun Jae Hoon Chung 《Applied microbiology》2000,66(2):476-480
Staphylokinase (SAK), a polypeptide secreted by Staphylococcus aureus, is a plasminogen activator with a therapeutic potential in thrombosis diseases. A Bacillus subtilis strain which is multiply deficient in exoproteases was transformed by an expression plasmid carrying a promoter and a signal sequence of subtilisin fused in frame with the sak open reading frame. However, the amount of SAK secretion was marginal (45 mg/liter). In contrast, disruption of the wprA gene, which encodes a subtilisin-type protease, strongly promoted the production of SAK in the stationary phase (181 mg/liter). In addition, the extracellular stability of mature SAK was dramatically enhanced. These data indicate a significant role of the wprA gene product in degrading foreign proteins, both during secretion and in the extracellular milieu. 相似文献
167.
Jong-Kuk Na Sun-Mi Huh In-Sun Yoon Myung-Ok Byun Yeon-Hee Lee Kyun-Oh Lee Dool-Yi Kim 《Molecular breeding : new strategies in plant improvement》2014,34(2):569-581
Yield of major monocotyledonous crops including wheat, rice, barley, and sorghum is greatly influenced by tillering. However, deciphering the underlying mechanisms of the tillering has long been hindered because many changeable factors are involved in the process. Plant two LIM-domain-containing proteins bind to and stabilize actin filaments that are major constituents in the formation of higher-order actin cytoskeleton. Here, we report that rice LIM-domain protein, OsPLIM2a, is involved in rice tillering likely through actin cytoskeleton organization. OsPLIM2 genes (OsPLIM2a, OsPLIM2b, and OsPLIM2c) expressed in reproductive organs including anthers, but not in other tissues. Analysis of both OsPLIM2a and OsPLIM2c promoter fused to GUS reporter revealed that both promoters directed strong and specific GUS expression in pollens. Transient expression of OsPLIM2a-GFP and OsPLIM2c-GFP in tobacco leaves showed that OsPLIM2a and OsPLIM2c could bind to actin filaments, which is consistent with other plant LIM proteins with actin-binding property. To examine further physiological roles of rice OsPLIM2a and OsPLIM2c, transgenic rice plants with 35S:OsPLIM2a or 35S:OsPLIM2c were examined for any phenotypic changes. Transgenic plants overexpressing OsPLIM2a produced bigger seeds than wild type, whereas they exhibited reduction in tiller numbers. These results suggest that OsPLIM2a may participate positively in seed development but negatively in tiller differentiation. Protein interaction assays using OsPLIM2c proteins revealed that OsPLIM2c interacted with at least three proteins including rice Fimbrin, of which homologs in Arabidopsis play crucial roles in pollen tube growth, implying that rice OsPLIM2c and Fimbrin may exert roles together in pollen tube growth. 相似文献
168.
Cellular senescence is a process by which cells enter a state of permanent cell cycle arrest. It is commonly believed to underlie organismal aging and age-associated diseases. However, the mechanism by which cellular senescence contributes to aging and age-associated pathologies remains unclear. Recent studies showed that senescent cells exert detrimental effects on the tissue microenvironment, generating pathological facilitators or aggravators. The most significant environmental effector resulting from senescent cells is the senescence-associated secretory phenotype (SASP), which is constituted by a strikingly increased expression and secretion of diverse pro-inflammatory cytokines. Careful investigation into the components of SASPs and their mechanism of action, may improve our understanding of the pathological backgrounds of age-associated diseases. In this review, we focus on the differential expression of SASP-related genes, in addition to SASP components, during the progress of senescence. We also provide a perspective on the possible action mechanisms of SASP components, and potential contributions of SASP-expressing senescent cells, to age-associated pathologies. [BMB Reports 2015; 48(10): 549-558] 相似文献
169.
Sangchul Lee Seong Jin Jeong Sung Il Hwang Sung Kyu Hong Hak Jong Lee Seok Soo Byun Gheeyoung Choe Sang Eun Lee 《PloS one》2015,10(4)
Objectives
There is little data about the clinical value of core length for prostate biopsy (PBx). We investigated the clinical values of various clinicopathological biopsy-related parameters, including core length, in the contemporary multi-core PBx.Patients and Methods
Medical records of 5,243 consecutive patients who received PBx at our institution were reviewed. Among them, 3,479 patients with prostate-specific antigen (PSA) ≤10ng/ml level who received transrectal ultrasound (TRUS)-guided multi (≥12)-core PBx at our institution were analyzed for prostate cancer (PCa). Gleason score upgrading (GSU) was analyzed in 339 patients who were diagnosed with low-risk PCa and received radical prostatectomy. Multivariate logistic regression analyses for PCa detection and prediction of GSU were performed.Results
The mean age and PSA of the entire cohort were 63.5 years and 5.4ng/ml, respectively. The overall cancer detection rate was 28.5%. There was no statistical difference in core length between patients diagnosed with PCa and those without PCa (16.1 ± 1.8 vs 16.1 ± 1.9mm, P = 0.945). The core length was also not significantly different (16.4 ± 1.7 vs 16.4 ± 1.6mm, P = 0.889) between the GSU group and non-GSU group. Multivariate logistic regression analyses demonstrated that the core length of PBx did not affect PCa detection in TRUS-guided multi-core PBx (P = 0.923) and was not prognostic for GSU in patients with low-risk PCa (P = 0.356).Conclusions
In patients undergoing contemporary multi-core PBx, core length may not have significant impact on PCa detection and also GSU following radical prostatectomy among low-risk PCa group. 相似文献170.
Young-Sun Lee Hyon-Seung Yi Yang-Gun Suh Jin-Seok Byun Hyuk Soo Eun So Yeon Kim Wonhyo Seo Jong-Min Jeong Won-Mook Choi Myung-Ho Kim Ji Hoon Kim Keun-Gyu Park Won-Il Jeong 《Molecules and cells》2015,38(11):998-1006
Retinols are metabolized into retinoic acids by alcohol dehydrogenase (ADH) and retinaldehyde dehydrogenase (Raldh). However, their roles have yet to be clarified in hepatitis despite enriched retinols in hepatic stellate cells (HSCs). Therefore, we investigated the effects of retinols on Concanavalin A (Con A)-mediated hepatitis.Con A was injected into wild type (WT), Raldh1 knock-out (Raldh1−/−), CCL2−/− and CCR2−/− mice. For migration study of regulatory T cells (Tregs), we used in vivo and ex vivo adoptive transfer systems. Blockade of retinol metabolism in mice given 4-methylpyrazole, an inhibitor of ADH, and ablated Raldh1 gene manifested increased migration of Tregs, eventually protected against Con A-mediated hepatitis by decreasing interferon-γ in T cells. Moreover, interferon-γ treatment increased the expression of ADH3 and Raldh1, but it suppressed that of CCL2 and IL-6 in HSCs. However, the expression of CCL2 and IL-6 was inversely increased upon the pharmacologic or genetic ablation of ADH3 and Raldh1 in HSCs. Indeed, IL-6 treatment increased CCR2 expression of Tregs. In migration assay, ablated CCR2 in Tregs showed reduced migration to HSCs. In adoptive transfer of Tregs in vivo and ex vivo, Raldh1-deficient mice showed more increased migration of Tregs than WT mice. Furthermore, inhibited retinol metabolism increased survival rate (75%) compared with that of the controls (25%) in Con A-induced hepatitis.These results suggest that blockade of retinol metabolism protects against acute liver injury by increased Treg migration, and it may represent a novel therapeutic strategy to control T cell-mediated acute hepatitis. 相似文献