全文获取类型
收费全文 | 682篇 |
免费 | 37篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 17篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 20篇 |
2017年 | 14篇 |
2016年 | 23篇 |
2015年 | 30篇 |
2014年 | 41篇 |
2013年 | 32篇 |
2012年 | 57篇 |
2011年 | 66篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 41篇 |
2007年 | 48篇 |
2006年 | 39篇 |
2005年 | 32篇 |
2004年 | 42篇 |
2003年 | 33篇 |
2002年 | 28篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有719条查询结果,搜索用时 171 毫秒
681.
Conjugates of auxin and cytokinin 总被引:1,自引:0,他引:1
Plant growth and developmental processes as well as environmental responses require the action and cross talk of phytohormones including auxins and cytokinins. Active phytohormones are changed into multiple forms by acylation, esterification or glycosylation, for example. It seems that conjugated compounds could serve as pool of inactive phytohormones that can be converted to active forms by de-conjugation reactions. The concept of reversible conjugation of auxins and cytokinins suggests that under changeable environmental, developmental or physiological conditions these compounds can be a source of free hormones. Phytohormones metabolism may result in a loss of activity and decrease the size of the bioactive pool. All metabolic steps are in principle irreversible, except for some processes such as the formation of ester, glucoside and amide conjugates, where the free compound can be liberated by enzymatic hydrolysis. The role, chemistry, synthesis and hydrolysis of conjugated forms of two classes of plant hormones are discussed. 相似文献
682.
Koprowska-Ratajska M Kluczyk A Stefanowicz P Bartosz-Bechowski H Szewczuk Z 《Amino acids》2009,36(2):309-315
A direct solid-phase synthesis of a series of substituted benzimidazole-containing peptides is described. The method involves
on-resin formation of new amino acids containing benzimidazole derivatives in the side chain. The heterocycle conjugates were
obtained by reaction between aldehydes and peptides containing β-(3,4-diaminophenyl)alanine residue, immobilized on a polymeric
solid support. 相似文献
683.
The chromosomes of three species from the genus Leuciscus (the ide L. idus, the European chub L. cephalus and the common dace L. leuciscus) were examined with the FISH technique for 5S and 28S rDNA probes. The analysis showed that among the three examined species, 5S rDNA signals were located on two large and four small subtelocentric chromosomes in L. leuciscus, on one large and five small subtelocentric chromosomes in L. idus, while in L. cephalus the probe signals were found on two metacentric chromosomes and one large and one small subtelocentric chromosome pairs. In all analysed species, the 28S rDNA probe signals were placed on only one chromosome pair, subtelocentric in the common dace and the European chub, and submetacentric in the ide. The three species differed in the number of sites in which both probe signals were present. In conclusion, the co-location of the 5S and 28S rDNA proved to be a useful cytogenetic marker among the studied fishes. Moreover, this marker could be adapted to other cyprinids. 相似文献
684.
Levels of Human Immunodeficiency Virus Type 1-Specific Cytotoxic T-Lymphocyte Effector and Memory Responses Decline after Suppression of Viremia with Highly Active Antiretroviral Therapy 总被引:15,自引:0,他引:15
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Spyros A. Kalams Philip J. Goulder Amy K. Shea Norman G. Jones Alicja K. Trocha Graham S. Ogg Bruce D. Walker 《Journal of virology》1999,73(8):6721-6728
Therapeutic suppression of human immunodeficiency virus type 1 (HIV-1) replication may help elucidate interactions between the host cellular immune responses and HIV-1 infection. We performed a detailed longitudinal evaluation of two subjects before and after the start of highly active antiretroviral therapy (HAART). Both subjects had evidence of in vivo-activated and memory cytotoxic T-lymphocyte precursor (CTLp) activity against multiple HIV-1 gene products. After the start of therapy, both subjects had declines in the levels of in vivo-activated HIV-1-specific CTLs and had immediate increases in circulating HIV-1-specific CTL memory cells. With continued therapy, and continued suppression of viral load, levels of memory CTLps declined. HLA A*0201 peptide tetramer staining demonstrated that declining levels of in vivo-activated CTL activity were associated with a decrease in the expression of the CD38(+) activation marker. Transient increases in viral load during continued therapy were associated with increases in the levels of virus-specific CTLps in both individuals. The results were confirmed by measuring CTL responses to discrete optimal epitopes. These studies illustrate the dynamic equilibrium between the host immune response and levels of viral antigen burden and suggest that efforts to augment HIV-1-specific immune responses in subjects on HAART may decrease the incidence of virologic relapse. 相似文献
685.
Alicja Ponder Ewelina Hallmann Martyna Kwolek Dominika
rednicka-Tober Renata Kazimierczak 《Current issues in molecular biology》2021,43(1):36
Anthocyanins are widely distributed secondary metabolites that play an essential role in skin pigmentation of many plant organs and microorganisms. Anthocyanins have been associated with a wide range of biological and pharmacological properties. They are also effective agents in the prevention and treatment of many chronic diseases. Berries are particularly abundant in these compounds; therefore, their dietary intake has health-promoting effects. The aim of this study was to identify and determine the anthocyanin content in selected species and cultivars of berry fruits, such as raspberry, blackberry, red currant, blackcurrant, and highbush blueberry, widely consumed by Europeans. The concentrations of anthocyanins were determined by HPLC, identifying individual compounds: cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside, delphinidin-3-O-glucoside, delphinidin-3-O-rutinoside, cyanidin-3-O-rutinoside, delphinidin-3-O-galactoside, cyanidin-3-O-galactoside, and malvidin-3-O-galactoside. The experimental data showed that the selected species and cultivars of berry fruits differ significantly in the contents of anthocyanins. Among all species tested, blackberry and blackcurrant were characterized significantly by the highest content of anthocyanins (sum), while the lowest content was found in red currant fruits. Additionally, the content of individual anthocyanin compounds in particular species and cultivars was also different. Considering the high content of anthocyanins and their potential positive impact on human health and protection against disease, berries should be part of healthy nutrition. 相似文献
686.
F. Javier Rodríguez-Rajo Diego Fdez-Sevilla Alicja Stach Victoria Jato 《Aerobiologia》2010,26(1):1-14
Pollen data recorded by a single sampler in any given city often fail to reflect particular events occurring in surrounding
areas. This is frequently overlooked when interpreting aerobiological results, and therefore pollen data obtained in urban
areas may not necessarily be representative of the situation in more rural areas of the same city. Our purpose is to assess
differences between allergenic pollen concentrations recorded in an urban area (Eskulap) and a rural/suburban (Morasko) of
the same city from 2005 to 2007. Anova-Manova Scheffe, Spearman correlation and Mixed-design ANOVA whitin-subjects effects
tests were applied. The results obtained have showed longer pollen seasons, earlier starts of flowering and later conclusion
in the urban area. The participation of arboreal pollen in the pollen fall of both sites had enough significative similarities
to determine that is linked to regional conditions, while differences in the atmospheric pollen content of herbaceous plants
between sites should be due to local conditions. 相似文献
687.
Paulina Paluchowska Marianna Tokarczyk Bozena Bogusz Iwona Skiba Alicja Budak 《Memórias do Instituto Oswaldo Cruz》2014,109(4):436-441
Over the last decades, Candida spp have been responsible for an
increasing number of infections, especially in patients requiring intensive care.
Knowledge of local epidemiology and analysis of the spread of these pathogens is
important in understanding and controlling their transmission. The aim of this study
was to evaluate the genetic diversity of 31 Candida albicans and
17 Candida glabrata isolates recovered from intensive care unit
patients from the tertiary hospital in Krakow between 2011-2012. The strains were
typed by random amplified polymorphic DNA (RAPD) polymerase chain reaction using five
primers (CD16AS, HP1247, ERIC-2, OPE-3 and OPE-18). The results of the present
investigation revealed a high degree of genetic diversity among the isolates. No
clonal relationship was found among the C. albicans strains, whereas
two C. glabrata isolates were identical. The source of
Candida infection appeared to be mostly endogenous; however, the presence
of two clonal C. glabrata strains suggested the possibility of
cross-transmission of these pathogens. Our study confirmed the high discriminatory
power of the RAPD technique in the molecular typing of Candida
clinical isolates. This method may be applied to the evaluation of transmission
routes of pathogenic fungi on a local level. 相似文献
688.
Tim Gruber Chenchen Pan Raian E. Contreras Tobias Wiedemann Donald A. Morgan Alicja A. Skowronski Sandrine Lefort Cahuê De Bernardis Murat Ophelia Le Thuc Beata Legutko Francisco J. Ruiz-Ojeda María de la Fuente-Fernández Angel Luis García-Villalón Daniel González-Hedström Melanie Huber Klara Szigeti-Buck Timo D. Müller Siegfried Ussar Cristina García-Cáceres 《Cell metabolism》2021,33(6):1155-1170.e10
- Download : Download high-res image (147KB)
- Download : Download full-size image
689.
Observation of Electrochemically Driven Elemental Segregation in a Si Alloy Thin‐Film Anode and its Effects on Cyclic Stability for Li‐Ion Batteries
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Minsub Oh Sekwon Na Chang‐Su Woo Jun‐Ho Jeong Sung‐Soo Kim Alicja Bachmatiuk Mark Hermann Rümmeli Seungmin Hyun Hoo‐Jeong Lee 《Liver Transplantation》2015,5(22)
The results of employing (Ti, Fe)‐alloyed Si thin‐film anode for Li‐ion batteries are reported. The material demonstrates an impressive cyclic stability with stable operation for more than 500 cycles at a capacity higher than 1400 mAh g?1. Materials characterization using scanning electron microscopy and transmission electron microscopy illuminates an intriguing materials process behind the performance: ripple‐like pattern formation via electrochemically driven segregation of the inactive elements (Ti and Fe). The ripple structure plays a buffer role by suppressing loss of the active material upon further cycling, allowing the anode to gradually transform into an array of microbumps. The morphological evolution helps the anode endure long cycles (even up to 1000 cycles) without catastrophic failure as the bumps shrank slowly and steadily, consistent with the electrochemical data. 相似文献
690.
Symplasmic short- and long-distance communication may be regulated at different levels of plant body organization. It depends on cell-to-cell transport modulated by plasmodesmata conductivity and frequency but above all on morphogenetic fields that integrate a plant at the supracellular level. Their control of physiological and developmental processes is especially important in trees, where the continuum consists of 3-dimensional systems of: 1) stem cells in cambium, and 2) living parenchyma cells in the secondary conductive tissues. We found that long-distance symplasmic transport in trees is spatially regulated. Uneven distribution of fluorescent tracer in cambial cells along the branches examined illustrates an unknown intrinsic phenomenon that can possibly be important for plant organism integration. Here we illustrate the spatial dynamics of symplasmic transport in cambium, test and exclude the role of callose in its regulation, and discuss the mechanism that could possibly be responsible for the maintenance of this spatial pattern. 相似文献