全文获取类型
收费全文 | 650篇 |
免费 | 55篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 21篇 |
2019年 | 21篇 |
2018年 | 26篇 |
2017年 | 27篇 |
2016年 | 31篇 |
2015年 | 34篇 |
2014年 | 47篇 |
2013年 | 53篇 |
2012年 | 53篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 29篇 |
2008年 | 28篇 |
2007年 | 32篇 |
2006年 | 25篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 14篇 |
2002年 | 21篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有705条查询结果,搜索用时 15 毫秒
181.
TT virus (TTV) is a newly described nonenveloped human virus, with a circular, negative-stranded DNA genome, that was first identified in the blood of a patient with posttransfusion hepatitis of unknown etiology. PCR primers and conditions used for TTV DNA amplification may greatly influence the level of TTV detection in serum. Three PCR assays, with different regions of the genome as targets, were used to test TTV DNA in 130 sera from children and adults visiting a hospital in the south of Brazil, most of them for routine procedure. Forty-four percent of adult sera and 73% of sera from children aged 0-10 years were TTV positive with at least one PCR assay. However, the three assays were able to detect only 33%, 35%, and 70% of the total positive samples. Our results showed a high prevalence of TTV infection in the south of Brazil, particularly among young children, and confirmed the necessity of performing several PCR assays to assess the true TTV prevalence in a determined population. 相似文献
182.
Real time monitoring biomass concentration in Streptomyces clavuligerus cultivations with industrial media using a capacitance probe 总被引:1,自引:0,他引:1
On-line monitoring biomass concentration in mycelial fed-batch cultivations of Streptomyces clavuligerus grown with soluble and partially insoluble complex media, was investigated with an in-situ capacitance probe fitted to an industrial pilot-plant tank. Standard off-line and on-line biomass determinations, including cell dry weight, packed mycelial volume, viscosity, DNA concentration and total CO(2) evolution in the exhaust gases, were performed throughout the experiments and compared to on-line capacitance measurements. Linear relations between capacitance and all other measurements were developed for both media that hold only in defined process phases, depending on the biomass state and the amount of insoluble matter present. For the industrial complex culture media good linear relations were obtained in the fast growth phase between capacitance and DNA concentration and total CO(2) evolution, while in the subsequent transition and stationary phases only with apparent viscosity was a reasonable correlation found. The capacitance probe was shown to be a valuable tool for real-time monitoring biomass concentration in industrial-like cultivation of mycelial streptomycetes. 相似文献
183.
J. S. Oliveira M. L. Costa A. Rodrigues J. G. A. Menezes A. M. L. Pereira 《Engineering in Life Science》1985,5(3):245-250
Positive and negative effects of dilution of raw effluents from swine breeding are discussed, as to the treatability of those waste waters. Its effects on oxygen consumption and on the variation of inhibitory actions possibly observed, are studied and quantified. Using BRADENDER and VANDEPUTTE techniques based on peptone degradation, and determining PHELPS'S equation parameters for different consumption curves observed, the advantages of dilution versus treatment of raw effluents is studied. 相似文献
184.
A L Bittencourt M Sadigursky A A Da Silva C A Menezes M M Marianetti S C Guerra I Sherlock 《Memórias do Instituto Oswaldo Cruz》1988,83(1):37-39
One hundred milk or colostrum samples from 78 mothers with chronic Chagas' disease were parasitologically studied for Trypanosoma cruzi infection by means of direct examination and inoculation of mice. The mice were submitted to direct blood examination three times a week. At the end of 45 days, xenodiagnosis and indirect immunofluorescent test (IFAT) for T. cruzi antibodies were carried out in the animals. No parasitized sample was observed even though five mothers had parasitemia at milk collection. In addition, 97 breast-fed children of chronic chagasic mothers, born free of infection, were tested for IgG antibodies to T. cruzi using IFAT. No case of T. cruzi infection was detected. The authors conclude that breast-feeding should not be avoided for children of chronic chagasic women. However, as these mothers had intermittent parasitemia, they should avoid nursing when there is nipple bleeding. 相似文献
185.
186.
J. S. Oliveira M. L. Costa A. Rodrigues J. G. A. Menezes M. C. Bori 《Engineering in Life Science》1985,5(3):251-261
Some aspects of the kinetics of bioremoval of pollutants during biodegradation of swine-breeding waste waters are studied and a biphasic model is proposed. The concentration of nitrogen and phosphorus compounds during the process is followed. Following a previous contribution on the same subject, the aspects of dilution of those effluents are discussed, and it is proposed to treat raw effluents, in spite of the reduction of possible biostatic actions. Dilution will be acceptable only if strong inhibitory effects are observed. 相似文献
187.
188.
Ludmila Correa Muniz Ana Maria Baptista Menezes Maria Cecília Formoso Assun??o Fernando Cesar Wehrmeister Jeovany Martínez-Mesa Helen Gon?alves Marlos Rodrigues Domingues Denise Petrucci Gigante Bernardo Lessa Horta Fernando C. Barros 《PloS one》2015,10(4)
Objective
To evaluate the effect of total breastfeeding, breastfeeding duration and type of breastfeeding at 3 months of age on bone mass at 18 and 30 years.Study Design
A prospective, longitudinal study was conducted with two birth cohorts (1982 and 1993) in Pelotas, Southern Brazil. Measurements of bone mineral content (BMC) and bone mineral density (BMD) at 18 and 30 years of age were obtained by dual-energy X-ray absorptiometry (DXA). Information on breastfeeding was collected during the first 4 years of life. Analyses were performed by linear regression and stratified by sex.Results
A total of 1109 and 3226 participants provided complete information on breastfeeding in early life and bone mass at 18 and 30 years, respectively. No association between breastfeeding and bone mass was observed in women at both ages nor among men at age 30. Among men at the age of 18, BMC and BMD were higher among those breastfed regardless of duration (p=0.032 and p=0.043, respectively).Conclusions
Despite a very weak positive effect of breastfeeding (yes/no) on BMC and BMD at age 18 in men, most findings pointed to a lack of association between breastfeeding and bone mass until young adulthood. 相似文献189.
Camila B?tto-Menezes M?nica Caroline Silva dos Santos Janicéia Lopes Simplício Jandira Menezes de Medeiros Kelly Cristina Barroso Gomes Isabel Cristina de Carvalho Costa Eva Batista-Silva Cristiana Teixeira do Nascimento Eda Cristina da Silva Chagas José Felipe Jardim Sardinha Franklin Sim?es de Santana Filho Marianna Brock Azucena Bardají Flor Ernestina Martínez-Espinosa 《PloS one》2015,10(12)
Introduction
Plasmodium vivax is the most prevalent malaria species in the American region. Brazil accounts for the higher number of the malaria cases reported in pregnant women in the Americas. This study aims to describe the characteristics of pregnant women with malaria in an endemic area of the Brazilian Amazon and the risk factors associated with prematurity and low birth weight (LBW).Methods/Principal Findings
Between December 2005 and March 2008, 503 pregnant women with malaria that attended a tertiary health centre were enrolled and followed up until delivery and reported a total of 1016 malaria episodes. More than half of study women (54%) were between 20–29 years old, and almost a third were adolescents. The prevalence of anaemia at enrolment was 59%. Most women (286/503) reported more than one malaria episode and most malaria episodes (84.5%, 846/1001) were due to P. vivax infection. Among women with only P. vivax malaria, the risk of preterm birth and low birth weight decreased in multigravidae (OR, 0.36 [95% CI, 0.16–0.82]; p = 0.015 and OR 0.24 [95% CI, 0.10–0.58]; p = 0.001, respectively). The risk of preterm birth decreased with higher maternal age (OR 0.43 [95% CI, 0.19–0.95]; p = 0.037) and among those women who reported higher antenatal care (ANC) attendance (OR, 0.32 [95% CI, 0.15–0.70]; p = 0.005).Conclusion
This study shows that P. vivax is the prevailing species among pregnant women with malaria in the region and shows that vivax clinical malaria may represent harmful consequences for the health of the mother and their offsprings particularly on specific groups such as adolescents, primigravidae and those women with lower ANC attendance. 相似文献190.
Network analysis reveals that bacteria and fungi form modules that correlate independently with soil parameters 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Environmental microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)