全文获取类型
收费全文 | 124篇 |
免费 | 8篇 |
出版年
2023年 | 2篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有132条查询结果,搜索用时 15 毫秒
1.
Cellobiase (beta-glucosidase) production was compared for two streptomycetes: Streptomyces flavogriseus, a known producer of cellulase complex, and Streptomyces sp. strain CB-12, a strain isolated for its rapid growth on cellobiose. The optimal conditions for enzyme activity were established in relation to pH, temperature, enzyme stability, and substrate affinity. The production of beta-glucosidase by the two strains depended on the carbon substrate in the medium. Cellobiose was found to repress the biosynthesis of the enzyme in S. flavogriseus and to stimulate its production in strain CB-12. The biosynthesis of the enzyme correlated well with the accumulation of glucose in the culture filtrates. The combined action of the beta-glucosidases produced by the two Streptomyces strains might allow a better utilization of the reaction products which arise during the biodegradation of cellulose. 相似文献
2.
Hyojung Cha George Fish Joel Luke Ahmad Alraddadi Hyun Hwi Lee Weimin Zhang Yifan Dong Saurav Limbu Andrew Wadsworth Iuliana P. Maria Laia Francs Hou Lon Sou Tian Du Ji‐Seon Kim Martyn A. McLachlan Iain McCulloch James R. Durrant 《Liver Transplantation》2019,9(27)
Here, it is investigated whether an energetic cascade between mixed and pure regions assists in suppressing recombination losses in non‐fullerene acceptor (NFA)‐based organic solar cells. The impact of polymer‐NFA blend composition upon morphology, energetics, charge carrier recombination kinetics, and photocurrent properties are studied. By changing film composition, morphological structures are varied from consisting of highly intermixed polymer‐NFA phases to consisting of both intermixed and pure phase. Cyclic voltammetry is employed to investigate the impact of blend morphology upon NFA lowest unoccupied molecular orbital (LUMO) level energetics. Transient absorption spectroscopy reveals the importance of an energetic cascade between mixed and pure phases in the electron–hole dynamics in order to well separate spatially localized electron–hole pairs. Raman spectroscopy is used to investigate the origin of energetic shift of NFA LUMO levels. It appears that the increase in NFA electron affinity in pure phases relative to mixed phases is correlated with a transition from a relatively planar backbone structure of NFA in pure, aggregated phases, to a more twisted structure in molecularly mixed phases. The studies focus on addressing whether aggregation‐dependent acceptor LUMO level energetics are a general design requirement for both fullerene and NFAs, and quantifying the magnitude, origin, and impact of such energetic shifts upon device performance. 相似文献
3.
Sicora Cosmin Ionel Chiș Iuliana Chiș Ciprian Sicora Oana 《Photosynthesis research》2019,139(1-3):461-473
Photosynthesis Research - Cyanobacteria, as well as green algae and higher plants, have highly conserved photosynthetic machinery. Cyanothece sp. ATCC 51142 is a unicellular, aerobic, diazotrophic... 相似文献
4.
Endotoxin tolerance is defined as a hyporesponsiveness state to a second stimulation with lipopolysaccharide (LPS). This refractory state is primarily associated with an attenuated cytokine production. Whether this down-regulation of cytokine production results in an increased susceptibility to infection remains a matter of controversy. The aim of this study was to investigate the resistance of tolerant mice to a subsequent bacterial infection and the role of bacterial immunomodulator CANTASTIM (CS) in this experimental model. We have shown that the LPS-tolerant mice (intraperitoneally inoculated with LPS Salmonella typhimurium 10 microg/mouse, daily for two days) were protected against a challenge with Pseudomonas aeruginosa (LD 100) administered 24 h later. On the contrary, when the animals were challenged 1 h after the last LPS injection, they did not survive. However if these animals were pre-treated with CS 3 days before LPS treatment, they became resistant to a subsequent bacterial challenge. More interestingly, if the treatment with LPS was substituted with CS (same schedule, route of administration and doses) there was a significant increase in the survival of mice challenged with Pseudomonas aeruginosa after either 1 h or 24 h. In this case, the increase in the rate of survival was correlated with an enhanced production of IL-10 in the peritoneal cavities of CS treated mice as compared to LPS treated mice. 相似文献
5.
Gangliosides from human melanoma tumors impair dendritic cell differentiation from monocytes and induce their apoptosis 总被引:18,自引:0,他引:18
Péguet-Navarro J Sportouch M Popa I Berthier O Schmitt D Portoukalian J 《Journal of immunology (Baltimore, Md. : 1950)》2003,170(7):3488-3494
Gangliosides are ubiquitous membrane-associated glycosphingolipids, which are involved in cell growth and differentiation. Most tumor cells synthesize and shed large amounts of gangliosides into their microenvironment, and many studies have unraveled their immunosuppressive properties. In the present study we analyzed the effects of GM3 and GD3 gangliosides, purified from human melanoma tumors, on the differentiation of monocyte-derived dendritic cells (MoDC). At concentrations close to those detected in the sera from melanoma patients, both gangliosides dose-dependently inhibit the phenotypic and functional differentiation of MoDC, as assessed by a strong down-regulation of CD1a, CD54, CD80, and CD40 Ags and impaired allostimulatory function on day 6 of culture. Furthermore, GM3 and GD3 gangliosides decreased the viable cell yield and induced significant DC apoptosis. Finally, addition of GD3 to differentiating DC impaired their subsequent maturation induced by CD154. The resulting DC produced low amounts of IL-12 and large amounts of IL-10, a cytokine pattern that might hamper an efficient antitumor immune response. In conclusion, the results demonstrate that gangliosides impair the phenotypic and functional differentiation of MoDC and induce their apoptosis, which may be an additional mechanism of human melanoma escape. 相似文献
6.
Mishra B Daruwala RS Zhou Y Ugel N Policriti A Antoniotti M Paxia S Rejali M Rudra A Cherepinsky V Silver N Casey W Piazza C Simeoni M Barbano P Spivak M Feng J Gill O Venkatesh M Cheng F Sun B Ioniata I Anantharaman T Hubbard EJ Pnueli A Harel D Chandru V Hariharan R Wigler M Park F Lin SC Lazebnik Y Winkler F Cantor CR Carbone A Gromov M 《Omics : a journal of integrative biology》2003,7(3):253-268
7.
8.
9.
Madoka Koyanagi Julie A Kerns Linda Chung Yan Zhang Scott Brown Tudor Moldoveanu Harmit S Malik Mark Bix 《BMC evolutionary biology》2010,10(1):223
Background
Interleukin-4 (IL4) is a secreted immunoregulatory cytokine critically involved in host protection from parasitic helminths [1]. Reasoning that helminths may have evolved mechanisms to antagonize IL4 to maximize their dispersal, we explored mammalian IL4 evolution. 相似文献10.
Caraş I Tucureanu C Lerescu L Sălăgeanu A 《Roumanian archives of microbiology and immunology》2007,66(1-2):5-9
Dendritic cells (DCs) play a pivotal role in linking innate and adaptive immunity. Migration to the lymph nodes and maturation of DCs are crucial steps in the initiation of specific immune responses. The bacterial product CANTASTIM (CS) is a purified extract of Pseudomonas aeruginosa that induces non-specific protection against bacterial infection, enhances macrophage effector functions and modulates cytokines production. In this study, we used a mouse skin explant culture model and human monocyte-derived DCs to study the effect of CS on the migration and maturation of DCs, respectively. We noticed a significant increase in the number of DCs which migrated from the skin explants when CS was added to the culture medium. Also, CS was able to induce the expression of maturation-associated marker CD83 on human monocyte-derived DCs. DC-based tumor vaccines represent a promising approach for cancer immunotherapy and the migration rate and maturation state of DCs are important parameters for their clinical effectiveness. CS may be an attractive candidate to be tested for the production of DC-based vaccine. 相似文献