全文获取类型
收费全文 | 311篇 |
免费 | 19篇 |
国内免费 | 5篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 22篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 19篇 |
2011年 | 34篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 21篇 |
2007年 | 12篇 |
2006年 | 13篇 |
2005年 | 17篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1984年 | 6篇 |
1975年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有335条查询结果,搜索用时 15 毫秒
101.
A search for the primary abnormality in adult-onset type II citrullinemia. 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《American journal of human genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
K Kobayashi N Shaheen R Kumashiro K Tanikawa W E O'Brien A L Beaudet T Saheki 《American journal of human genetics》1993,53(5):1024-1030
Deficiency of argininosuccinate synthetase (ASS) causes citrullinemia in human beings. Type II citrullinemia is found in most patients with adult-onset citrullinemia in Japan, and ASS deficiency is found specifically in the liver. Previous studies have shown that the decrease of hepatic ASS activity is caused by a decrease in enzyme protein with normal kinetic properties and that there were no apparent abnormalities in the amount, translational activity, and gross structure of hepatic ASS mRNA. In the present work, we show by sequencing analysis that there was no mutation in the ASS mRNA from two patients with type II citrullinemia. We also report RFLP analysis of a consanguineous family with type II citrullinemia, by using three DNA polymorphisms located within the ASS gene locus. In spite of having consanguineous parents, the patient was not a homozygous haplotype for the ASS gene. The RFLP analysis of 16 affected patients from consanguineous parents showed that 5 of 16 patients had the heterozygous pattern for one of the three DNA probes and that the frequency of the heterozygous haplotype was not different from the control frequency. These results suggest that the primary defect of type II citrullinemia is not within the ASS gene locus. 相似文献
102.
103.
Siddiqui BS Rasheed M Ilyas F Gulzar T Tariq RM Naqvi SN 《Zeitschrift für Naturforschung. C, Journal of biosciences》2004,59(1-2):104-112
As a result of chemical investigation on the ethanolic extract of fresh fruit coatings of Azadirachta indica A. Juss. (neem), twenty-seven compounds were identified in non-polar to less polar fractions which showed pesticidal activity determined by WHO method against Anopheles stephensi Liston. These identifications were basically made through GC-EIMS and were further supported by other spectroscopic techniques, including 13C NMR, UV and FTIR as well as retention indices. Thus sixteen n-alkanes, 1-16; three aromatics 2,6-bis-(1,1-dimethylethyl)-4-methyl phenol (17), 2-(phenylmethylene)-octanal (20), 1,2,4-trimethoxy-5-(1Z-propenyl)-benzene (27); three benzopyranoids 3,4-dihydro-4,4,5,8-tetramethylcoumarin (18), 3,4-dihydro-4,4,7,8-tetramethylcoumarin-6-ol (19), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[g]-2-benzopyran (22); one sesquiterpene methyl-3,7,11-trimethyl-2E,6E,10-dodecatrienoate (21); three esters of fatty acids methyl 14-methyl-pentadecanoate (23), ethyl hexadecanoate (24), ethyl 9Z-octadecenoate (25) and one monoterpene 3,7-dimethyl-1-octen-7-ol (26) were identified. Except 6, 8, 24 and 25 all these compounds were identified for the first time from the pericarp and fifteen of these, 1-3, 7, 9, 10, 17-23, 26, 27, are hitherto unreported previously from any part of the tree. Although this tree is a rich source of various natural products, it is the first report of identification of mono- and sesquiterpenes 26 and 21 and a potent antioxidant, 17. 相似文献
104.
Industrial and culture collection strains of solvent-producing clostridia, classified as Clostridium acetobutylicum, Clostridium beijerinckii, Clostridium saccharobutylicum, and Clostridium saccharoperbutylacetonicum were utilised in a comparative study of fermentation performance in a laboratory fermentation medium, a molasses fermentation medium, and a maize fermentation medium under standardised culture conditions. At least one representative strain was selected from each of the sub-groups within the four species. Preliminary evaluations were first undertaken for the three different fermentation media to determine the most appropriate media formulations, carbohydrate concentrations, and culture conditions for comparison of the solvent-producing ability of these strains. Standardised fermentation media and culture conditions were then selected for each of the comparative fermentation studies. These included TYA medium containing 4% glucose, a supplemented molasses medium containing 6% fermentable sugars, and a supplemented maize mash medium containing 8% maize. Additional comparative fermentation studies on industrial strains belonging to two species of solvent-producing clostridia were carried out in molasses containing higher concentrations of fermentable sugars, and the sugar concentrations supporting maximum levels of solvent production were determined. Although all the strains tested grew in the maize fermentation medium and degraded starch, only a few strains produced consistently high solvent levels. Optimum starch utilisation and solvent production was obtained at a maize concentration of 80 g/l. Pretreatment of the maize by milling or saccharification decreased the buffering capacity of the medium and resulted in decreased solvent production. Decreasing the time used to gelatinise the starch had little effect. Solvent yields and concentrations obtained in this study were compared with various published data in the scientific and patent literature and appeared to closely simulate the results obtained in the industrial fermentation process. The fermentation performances of individual strains could provide useful comparative data for the selection and development of strains for use on various commercial fermentation substrates. 相似文献
105.
Razia Sultana Bina Shaheen Siddiqui Kambiz Taraz Herbert Budzikiewicz Jean-Marie Meyer 《Biometals》2000,13(2):147-152
From Pseudomonas putida CFML 90-51 – a hospital isolate – a pyoverdine was obtained which is characterized by the unusual linkage by the -rather than the -amino group of Lys in the peptide chain. The structure elucidation by spectroscopic methods and degradation reactions is reported. 相似文献
106.
Shaheen PA Stehlik LL Meise CJ Stoner AW Manderson JP Adams DL 《Journal of experimental marine biology and ecology》2001,257(1):37-51
Field and laboratory investigations were conducted to examine feeding by newly settled winter flounder (Pseudopleuronectes americanus) on two co-occurring calanoid copepods, Eurytemora affinis and Acartia hudsonica. During the spring, these prey are present when winter flounder initiate their demersal lifestyle in estuaries of the northeastern United States. Epibenthic zooplankton were collected concurrently with winter flounder in the Navesink River estuary, NJ, in May 1998 and 1999. Although both calanoid species were in the estuary during the 2-year survey, E. affinis was consumed nearly to the exclusion of A. hudsonica by newly settled winter flounder. Annually, E. affinis and A. hudsonica had similar size distributions in field collections, indicating that species choice was not size selective. However, when preying on E. affinis, winter flounder preferred the larger sized organisms. In single species laboratory experiments, E. affinis and A. hudsonica were consumed equally by newly settled winter flounder (19-23 mm TL), but there were more strikes made toward E. affinis. Despite the lower catch efficiency, E. affinis was selected over A. hudsonica when the prey species were offered together in equal numbers. The selection for E. affinis over A. hudsonica by newly settled winter flounder may be the result of behavioral and/or morphological differences in the prey species. 相似文献
107.
Hugues Fouotsa Alain Meli Lannang Celine Djama Mbazoa Saima Rasheed Bishnu P. Marasini Zulfiqar Ali Krishna Prasad Devkota Augustin Ephrem Kengfack Farzana Shaheen Muhammad Iqbal Choudhary Norbert Sewald 《Phytochemistry letters》2012,5(2):236-239
One new xanthone, caroxanthone (1) together with six known xanthones, 4-prenyl-2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone (2), smeathxanthone A (3), gartanin (4), euxanthone (5), 8-hydroxycudraxanthone G (6) and morusignin I (7) were isolated from the stem bark of Garcinia nobilis. The structures were determined by 1D- and 2D-NMR techniques. All these compounds were tested for anti-glycation, α-glucosidase and α-chymotrypsin activities. Some of them exhibited strong to moderate α-glucosidase activities, while none of them inhibited α-chymotrypsin. Compounds 6 and 7 were found to be modest α-glucosidase inhibitors with IC50 values of 76 μM and 84 μM, respectively. 相似文献
108.
Naoya Miura Sharif M. Shaheen Hidetaka Akita Takashi Nakamura Hideyoshi Harashima 《Nucleic acids research》2015,43(3):1317-1331
Technologies that delivery antigen-encoded plasmid DNA (pDNA) to antigen presenting cell and their immune-activation are required for the success of DNA vaccines. Here we report on an artificial nanoparticle that can achieve these; a multifunctional envelope-type nanodevice modified with KALA, a peptide that forms α-helical structure at physiological pH (KALA-MEND). KALA modification and the removal of the CpG-motifs from the pDNA synergistically boosted transfection efficacy. In parallel, transfection with the KALA-MEND enhances the production of multiple cytokines and chemokines and co-stimulatory molecules via the Toll-like receptor 9-independent manner. Endosome-fusogenic lipid envelops and a long length of pDNA are essential for this immune stimulation. Furthermore, cytoplasmic dsDNA sensors that are related to the STING/TBK1 pathway and inflammasome are involved in IFN-β and IL-1β production, respectively. Consequently, the robust induction of antigen-specific cytotoxic T-lymphoma activity and the resulting prophylactic and therapeutic anti-tumor effect was observed in mice that had been immunized with bone marrow-derived dendritic cells ex vivo transfected with antigen-encoding pDNA. Collectively, the KALA-MEND possesses dual functions; gene transfection system and immune-stimulative adjuvant, those are both necessary for the successful DNA vaccine. 相似文献
109.
J. Nyagol G. De Falco S. Lazzi A. Luzzi G. Cerino S. Shaheen N. Palummo C. Bellan D. Spina L. Leoncini 《Journal of Hematopathology》2008,1(1):3-10
Angiogenic switch marks the beginning of tumor’s strategy to acquire independent blood supply. In some subtypes of non-Hodgkin’s lymphomas, higher local vascular endothelial growth factor (VEGF) expression correlates with increased microvessel density. However, this local VEGF expression is higher only in tumors with elevated expression of the receptors of the growth factor, suggesting an autocrine growth-promoting feedback loop. Several studies have indicated that VEGF receptors are also targeted by Tat protein from the HIV-1-infected cells. Given the similarity of the basic region of Tat to the angiogenic factors (basic fibroblast growth factor, VEGF), Tat mimics these proteins and binds to their receptors. We evaluated the role of HIV-1 Tat in regulating the level of VEGF expression and microvessel density in the AIDS-related diffuse large B-cell (DLBCL) and Burkitt lymphomas (BL). By luciferase assay, we showed that VEGF promoter activity was downregulated in vitro in cells transfected with Tat. Reduced VEGF protein expression in primary HIV-1 positive BL and DLBCL, compared to the negative cases, supported the findings of promoter downregulation from the cell lines. Microvascular density assessed by CD34 expression was, however, higher in HIV-1 positive than in HIV-1 negative tumors. These results suggest that Tat has a wider angiogenic role, besides the regulation of VEGF expression. Thus, targeting Tat protein itself and stabilizing transient silencing of VEGF expression or use of monoclonal antibodies against their receptors in the AIDS-associated tumors will open a window for future explorable pathways in the management of angiogenic phenotypes in the AIDS-associated non-Hodgkin’s lymphomas. 相似文献
110.