全文获取类型
收费全文 | 364篇 |
免费 | 16篇 |
专业分类
380篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 19篇 |
2012年 | 26篇 |
2011年 | 23篇 |
2010年 | 15篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 16篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有380条查询结果,搜索用时 0 毫秒
271.
Santos FR Ferraz DB Daghastanli KR Ramalho-Pinto FJ Ciancaglini P 《The Journal of membrane biology》2006,210(3):173-181
Liposomes have long been used as models for lipid membranes and for the reconstitution of a single or multiple proteins. Also,
liposomes have adjuvant activity in vaccines against several protozoan or bacterial organisms. Thus, the main objective of
the present study was to obtain a crude extract of detergent-solubilized proteins of Leishmania amazonensis amastigotes and reconstitute them into liposomes. Neutral and zwiterionic detergents were less efficient than an ionic detergent.
In order to obtain efficient solubilization using only sodium dodecyl sulfate (SDS), the effects of detergent and protein
concentration and incubation time were studied. The maximum of solubilized proteins was obtained instantaneously using a ratio
of 0.5 mg/ml of protein to 0.1% (w/v) detergent at 4°C. Dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylserine
(DPPS) and cholesterol in a weight ratio of 5:1:4 were used for protein reconstitution into liposomes using the cosolubilization
method, yielding 60% of incorporation. The incorporation of multiple parasite proteins results in a vesicular diameter of
proteoliposomes of about 140 nm, presenting a final lipid weight ratio for DPPC, DPPS and cholesterol of 1:1:5, with high
stability. The detergent-solubilized proteins of L. amazonensis amastigotes present in the proteoliposome, when analyzed by SDS-polyacrylamide gel electrophoresis, include a wide range
of parasite-incorporated proteins. BALB/c mice inoculated with these proteoliposomes were able to produce antibodies against
the proteins reconstituted in DPPC:DPPS:cholesterol liposomes and were partially resistant to infection with L. amazonensis promastigotes. These results indicate that this system can be used as a possible vaccine against L. amazonensis. 相似文献
272.
Raquel Ferraz Clarissa Ferreira Cunha Maria Inês Pimentel Marcelo Rosandiski Lyra Armando Oliveira Schubach Sérgio Coutinho Furtado de Mendon?a Alda Maria Da-Cruz Alvaro Luiz Bertho 《Memórias do Instituto Oswaldo Cruz》2015,110(5):596-605
In human cutaneous leishmaniasis (CL), the immune response is mainly mediated byT-cells. The role of CD8+ T-lymphocytes, which are related to healing ordeleterious functions, in affecting clinical outcome is controversial. The aim ofthis study was to evaluate T-cell receptor diversity in late-differentiated effector(LDE) and memory CD8+ T-cell subsets in order to create a profile ofspecific clones engaged in deleterious or protective CL immune responses. Healthysubjects, patients with active disease (PAD) and clinically cured patients wereenrolled in the study. Total CD8+ T-lymphocytes showed a disturbance inthe expression of the Vβ2, Vβ9, Vβ13.2, Vβ18 and Vβ23 families. The analyses ofCD8+T-lymphocyte subsets showed high frequencies of LDECD8+T-lymphocytes expressing Vβ12 and Vβ22 in PAD, as well aseffector-memory CD8+ T-cells expressing Vβ22. We also observed lowfrequencies of effector and central-memory CD8+ T-cells expressing Vβ2 inPAD, which correlated with a greater lesion size. Particular Vβ expansions point toCD8+ T-cell clones that are selected during CL immune responses,suggesting that CD8+ T-lymphocytes expressing Vβ12 or Vβ22 are involved ina LDE response and that Vβ2 contractions in memory CD8+T-cells areassociated with larger lesions. 相似文献
273.
Karina Gonzalez-Aldaco Jo?o R. Rebello Pinho Sonia Roman Ketti Gleyzer Nora A. Fierro Leticia Oyakawa Omar Ramos-Lopez Rubia A. Ferraz Santana Roberta Sitnik Arturo Panduro 《PloS one》2016,11(1)
Aim
To analyze the genetic heterogeneity of the Amerindian and admixed population (Mestizos) based on the IL28B (rs12979860, rs8099917) and IFNL4 (rs368234815) haplotypes, and their association with spontaneous clearance (SC) and liver damage in patients with hepatitis C infection from West Mexico.Methods
A total of 711 subjects from West Mexico (181 Amerindians and 530 Mestizos) were studied for the prevalence of IL28B (rs12979860C/T, rs8099917G/T) and IFNL4 (rs368234815∆G/TT) genotypes. A case-control study was performed in 234 treatment-naïve HCV Mestizos (149 chronic hepatitis C and 85 with SC) for the association of haplotypes with SC and liver damage. A real-time PCR assay was used for genotyping, and transitional elastography staged liver damage.Results
Significant Fst-values indicated differentiation between the studied populations. The frequencies of the protective C, T, TT alleles were significantly lower in the Amerindians than in Mestizos (p<0.05). The r2 measure of linkage disequilibrium was significant for all variants and the T/G/ΔG risk haplotype predominated in Amerindians and secondly in Mestizos. The protective C/T/TT haplotype was associated with SC (OR = 0.46, 95% IC 0.22–0.95, p = 0.03) and less liver damage (OR = 0.32, 95% IC 0.10–0.97, p = 0.04) in chronic patients. The Structure software analysis demonstrated no significant differences in ancestry among SC and chronic patients.Conclusions
West Mexico´s population is genetically heterogeneous at the IL28B/IFNL4 polymorphisms. The T/G/ΔG high-risk haplotype predominated in Amerindians and the beneficial alternative haplotype in Mestizos. The C/T/TT haplotype was associated with SC and less liver damage in chronically infected Mestizo patients. 相似文献274.
Martins LM Wanke B Lazéra Mdos S Trilles L Barbosa GG Macedo RC Cavalcanti Mdo A Eulálio KD Castro JA Silva AS Nascimento FF Gouveia VA Monte SJ 《Memórias do Instituto Oswaldo Cruz》2011,106(6):725-730
Throughout Brazil, Cryptococcus neoformans is the cause of cryptococcosis, whereas Cryptococcus gattii is endemic to the northern and northeastern states. In this study, the molecular types of 63 cryptococcal isolates recovered from the cerebrospinal fluid of meningitis patients diagnosed between 2008-2010 in Teresina, Piauí, Brazil, were analysed. Out of the 63 patients, 37 (58.7%) were human immunodeficiency virus (HIV)-positive and 26 (41.3%) were HIV-negative. URA5-restriction fragment length polymorphism analysis identified 37/63 (58.7%) isolates as the C. neoformans VNI genotype, predominantly in HIV-positive patients (32/37, 86.5%), and 24/63 (38.1%) as the C. gattii VGII genotype, mostly in HIV-negative patients (21/26, 80.8%). The occurrence of C. gattii VGII in six apparently healthy children and in seven adolescents/young adults in this region reaffirms the endemic occurrence of C. gattii VGII-induced primary cryptococcosis and early cryptococcal infection. Lethality occurred in 18/37 (48.6%) of the HIV-positive subjects and in 13/26 (50%) of the HIV-negative patients. Our results provide new information on the molecular epidemiology of C. neoformans and C. gattii in Brazilian endemic areas. 相似文献
275.
Construction, expression and unexpected regulatory properties of a tropomyosin mutant with a 31-residue deletion at the C-terminus (exon 9) 总被引:2,自引:0,他引:2
A Bartegi C Ferraz A Fattoum J Sri Widada F Heitz R Kassab J P Liautard 《European journal of biochemistry》1990,194(3):845-852
The cDNA coding for human skeletal muscle beta-tropomyosin was expressed in Escherichia coli to produce an unacetylated beta-tropomyosin. This cDNA was deleted from the sequence corresponding to the exon 9 and expressed in E. coli to produce an unacetylated beta-tropomyosin mutant lacking the C-terminal residues 254-284. The main structural and functional properties of the two isolated proteins, designated tropomyosin-1 and des-(254-284)-tropomyosin, respectively, were characterized in comparison with those of the genuine rabbit skeletal muscle alpha beta-tropomyosin. The folding and thermal stability of the three tropomyosins were indistinguishable. Tropomyosin-1, but not des-(254-284)-tropomyosin, was polymerized in the presence of troponin and did bind to actin in the presence of the troponin complex. Despite its weak binding to actin, des-(254-284)-tropomyosin displayed a regulatory function in the presence of troponin with a marked activation of the actomyosin subfragment-1 ATPase in the presence of Ca2+ and low concentrations of subfragment-1. The data were interpreted in the light of the allosteric models of regulation and suggest the involvement of the sequence coded by exon 9 in the stabilization by tropomyosin of the off state of the thin filament. 相似文献
276.
M.A.M.M. Ferraz R. Morató M. Yeste N. Arcarons A.I. Pena C. Tamargo C.O. Hidalgo R. Muiño T. Mogas 《Theriogenology》2014
The present study examined the relationship between the relative amount of high motile sperm and sperm–oocyte interactions obtained from Holstein bull ejaculates. Post-thaw sperm motility was analyzed using a computer-assisted sperm analyzer system and evaluated to determine the sperm motility subpopulations. Adhesion and penetration of zona pellucida (ZP) and pronucleus formation using post-thawed samples (15 ejaculates form 5 different bulls) with different percentages of sperm in the subpopulation with the fastest and most progressive subpopulation (subpopulation 4 [SP4]) were analyzed. The correlation between the proportion of sperm in SP4 and the number of spermatozoa bound to the zona pellucida (ZBA), the penetration rate, and the rate of pronucleus formation were calculated. A significant (P < 0.05) and positive correlation was found between the number of spermatozoa bound to the zona pellucida, the penetration rate, and the rate of pronucleus formation with the proportion of sperm in SP4 (r = 0.79, r = 0.66, and r = 0.63, respectively). Our results suggest that this specific high motile and progressive subpopulation is positively and significantly correlated with the ability of a thawed bull semen sample to interact properly with the oocyte and its extracellular vestments. These findings emphasize the relevance of analyzing semen subpopulation composition to predict bull sperm fertilizing ability and to select Holstein bulls for breeding purposes. 相似文献
277.
278.
Fernanda M. Mendes Debora F. Laurito Mariana Bazzeggio André Ferraz Adriane M. F. Milagres 《Biotechnology progress》2013,29(4):890-895
Sugar cane bagasse is recalcitrant to enzymatic digestion, which hinders the efficient conversion of its polysaccharides into fermentable sugars. Alkaline‐sulfite pretreatment was used to overcome the sugar cane bagasse recalcitrance. Chemical and structural changes that occurred during the pretreatment were correlated with the efficiency of the enzymatic digestion of the polysaccharides. The first 30 min of pretreatment, which removed approximately half of the initial lignin and 30% of hemicellulose seemed responsible for a significant enhancement of the cellulose conversion level, which reached 64%. After the first 30 min of pretreatment, delignification increased slightly, and hemicellulose removal was not enhanced; however, acid groups continued to be introduced into the residual lignin. Water retention values were 145% to the untreated bagasse and 210% to the bagasse pretreated for 120 min and fiber widths increased from 10.4 to 30 μm, respectively. These changes were responsible for an additional increase in the efficiency of enzymatic hydrolysis of the cellulose, which reached 92% with the 120 min pretreated sample. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:890–895, 2013 相似文献
279.
Brunna Xavier Martins Raul Ferraz Arruda Gildeíde Aparecida Costa Hassan Jerdy Sávio Bastos de Souza Julianna Maria Santos William Rodrigues de Freitas Milton Masahiko Kanashiro Eulógio Carlos Queiroz de Carvalho Nadir Francisca SantAnna Fernanda Antunes Raul Martinez-Zaguilan Sennoune Souad Anna Lvovna Okorokova-Fa?anha Arnoldo Rocha Fa?anha 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(1):1-12
Background
Metastatic tumor cells have acidic extracellular pH and differential electrochemical H+ gradients generated across their cell membranes by V-type H+-ATPases. This study shows that inhibition of the V-ATPases by the plant-derived monoterpene Myrtenal results in tumor cell death and decreased metastatic dissemination in mice.Methods
The Myrtenal anticancer toxicity was evaluated in vitro using murine (B16F0 and B16F10) and human (SkMel-5) melanoma cell lines, and in in vivo mouse metastatic dissemination model. Proton flux and extracellular acidification were directly evaluated at the surface of living cells using a non-invasive selective ion electrode approach.Results
The inhibition of V-ATPases by 100?μM Myrtenal disrupted the electrochemical H+ gradient across the cell membranes, strongly induced cell death (4–5 fold), and decreased tumor cells migration and invasion in vitro. Myrtenal (15?mg/kg) also significantly reduced metastasis induced by B16F10 in vivo, further reinforcing that V-ATPase is a molecular target to halt the progression of cancers.Conclusions
These data revealed the therapeutic potential of Myrtenal as inhibitor of melanoma progression proposing a mechanism of action by which once inhibited by this monoterpene the proton pumps fail to activate cancer-related differential electrochemical gradients and H+ fluxes across the tumor cell membranes, disrupting pH signatures inherent in tumor progression, resulting in reprogrammed cell death and metastasis inhibition.General significance
The work represents a new mechanistic strategy for contention of melanoma, the most aggressive and deadly form of cutaneous neoplasm, and highlights Myrtenal, other related monoterpenes and derivatives as promising proton pump inhibitors with high chemotherapeutic potential. 相似文献280.
M. C. M. Alvim-Ferraz M. C. Pereira J. M. Ferraz A. M. C. Almeida e Mello F. G. Martins 《人类与生态风险评估》2005,11(3):607-616
This study analyzes the air pollutant concentrations in the Oporto Metropolitan Area, Portugal, comparing them with the limits fixed by the previous legislation currently in force, as well as by European Union (EU) Directives. The impacts were estimated using the prevalence of asthmatic symptoms and asthma in children as indicators. The objectives were: (i) to evaluate the impact on air quality associated with the reduction of sulphur content in fuels, (ii) to compare health impacts associated with SO2 and particles with the limits fixed by both legislations, and (iii) to assess whether the delayed application of the EU Directives can be associated with health risks. It was concluded that: (i) after the reduction of sulphur content in fuels, a reduction of 60% of the annual averages of SO2 concentration was observed, as well as a decrease in the rates of asthmatic symptoms and asthma in children, (ii) the limits fixed by the previous legislation do not protect against health impacts of SO2 and particles, but the new EU Directives are protective; the EU limits for PM10 are very difficult to attain, being probably unnecessarily low concerning the impact on asthmatic symptoms and asthma in children, and (iii) the delayed application of the EU Directives can be associated with unnecessary health risks. 相似文献