全文获取类型
收费全文 | 499篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
522篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 20篇 |
2017年 | 17篇 |
2016年 | 11篇 |
2015年 | 22篇 |
2014年 | 17篇 |
2013年 | 51篇 |
2012年 | 38篇 |
2011年 | 44篇 |
2010年 | 28篇 |
2009年 | 28篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 22篇 |
2005年 | 17篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1973年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有522条查询结果,搜索用时 0 毫秒
111.
Gamma proteobacteria can nodulate legumes of the genus Hedysarum 总被引:1,自引:0,他引:1
Benhizia Y Benhizia H Benguedouar A Muresu R Giacomini A Squartini A 《Systematic and applied microbiology》2004,27(4):462-468
The bacteria hosted in the root nodules of the three Mediterranean wild legume species Hedysarum carnosum, Hedysarum spinosissimum subsp. capitatum, and Hedysarum pallidum, growing in native stands in different habitats in Algeria were isolated. Bacteria were recovered on yeast-mannitol-agar or on minimal media from a total of 52 nodules. Isolates were analyzed by Amplified Ribosomal DNA Restriction Analysis (ARDRA) using the enzyme CfoI, and further sorted by RAPD fingerprinting. A total of ten different types were found and their amplified 16S rDNA was sequenced and compared to databases. The BLAST alignment indicates that all the species whose sequences share 98 to 100% identity to the bacteria found in these nodules belong to the class Gammaproteobacteria and include Pantoea agglomerans, Enterobacter kobei, Enterobacter cloacae, Leclercia adecarboxylata, Escherichia vulneris, and Pseudomonas sp. No evidence of any rhizobial-like sequence was found even upon amplifying from the bulk of microbial cells obtained from the squashed nodules, suggesting that the exclusive occupants of the nodules formed by the three plants tested are members of the orders Enterobacteriales or Pseudomonadales. This is the first report of Gammaproteobacteria associated with legume nodules. Despite the presence of the related crop plant Hedysarum coronarium, specifically nodulated by Rhizobium sullae, these three Hedysarum species demonstrate to have undergone a separate path in terms of endophytic interactions with bacteria. An hypothesis to account for differences between the symbiotic relationships engaged by man-managed legumes, and those found in plants whose ecology is independent from human action, is discussed. 相似文献
112.
Bouchlaka Souissi Chiraz Ammar Myriam Zarra Ines Jordan Catherine Bouazizi Fatma Cheour Ilhem Tekaya Raoudha Zeglaoui Hela Fourati Hela Bouajina Elyes Doss Nejib Helms Cindy Elgaaied Amel Sellami Slaheddine 《Molecular biology reports》2014,41(6):4141-4146
A deletion of two genes from the late cornified envelope (LCE), LCE3B and LCE3C within epidermal differentiation complex on chromosome 1 was shown to be associated with both psoriasis and psoriatic arthritis (PsA) in several populations. To assess whether this deletion may contribute to the genetic predisposition to PsA in Tunisia, a total of 73 patients with PsA and 120 healthy matched controls were screened for the deletion, LCE3C_LCE3B-del, and its tag SNP, rs4112788. We also evaluated a possible relationship between PSORS1 and LCE3C_LCE3B-del through genotyping two proxy markers to HLA-C (rs12191877 and rs2073048). Our results did not provide evidence for association between the LCE3C_LCE3B-del nor the rs4112788 and the PsA. Similarly, no significant epistatic effect was observed. Our data suggest that The LCE deletion, previously identified in patients with psoriasis, is not of a major importance in the development of PsA in Tunisian patients supporting the current perception that different genetic risk factors contribute to skin and joint disease. However, these results need to be confirmed by additional large-scale studies of Tunisian PsA patients and controls. 相似文献
113.
Elizabeth D. Hutchins Glenn J. Markov Walter L. Eckalbar Rajani M. George Jesse M. King Minami A. Tokuyama Lauren A. Geiger Nataliya Emmert Michael J. Ammar April N. Allen Ashley L. Siniard Jason J. Corneveaux Rebecca E. Fisher Juli Wade Dale F. DeNardo J. Alan Rawls Matthew J. Huentelman Jeanne Wilson-Rawls Kenro Kusumi 《PloS one》2014,9(8)
114.
Ammar Khairullah Laura Cousino Klein Suzanne M. Ingle Margaret T. May Courtney A. Whetzel Elizabeth J. Susman Tomá? Paus 《PloS one》2014,9(9)
Purpose
Pubertal dynamics plays an important role in physical and psychological development of children and adolescents. We aim to provide reference ranges of plasma testosterone in a large longitudinal sample. Furthermore, we describe a measure of testosterone trajectories during adolescence that can be used in future investigations of development.Methods
We carried out longitudinal measurements of plasma testosterone in 2,216 samples obtained from 513 males (9 to 17 years of age) from the Avon Longitudinal Study of Parents and Children. We used integration of a model fitted to each participant’s testosterone trajectory to calculate a measure of average exposure to testosterone over adolescence. We pooled these data with corresponding values reported in the literature to provide a reference range of testosterone levels in males between the ages of 6 and 19 years.Results
The average values of total testosterone in the ALSPAC sample range from 0.82 nmol/L (Standard Deviation [SD]: 0.09) at 9 years of age to 16.5 (SD: 2.65) nmol/L at 17 years of age; these values are congruent with other reports in the literature. The average exposure to testosterone is associated with different features of testosterone trajectories such as Peak Testosterone Change, Age at Peak Testosterone Change, and Testosterone at 17 years of age as well as the timing of the growth spurt during puberty.Conclusions
The average exposure to testosterone is a useful measure for future investigations using testosterone trajectories to examine pubertal dynamics. 相似文献115.
116.
The cold shock protein family consists of the transfer of the foodborne pathogen Listeria monocytogenes from 37 to 4 and ?20?°C and was characterized by the sharp induction of a low molecular mass protein. This major cold shock protein ferritin-like protein (Flp) has an important role in regulation of various microbial physiological processes. Flp have a molecular mass of about 18?kDa, as observed on SDS?CPAGE. The purification procedure including ammonium sulfate fractionation was used. Monospecific polyclonal antibodies raised in rabbits against the purified new Flp immunostained a single 18-kDa Flp band in extracts from different cytoplasmic proteins blotted onto nitrocellulose. A 411-bp cDNA fragment that corresponds to an internal region of an flp gene was obtained by RT-PCR. Our result indicated a surexpression of major cold shock protein and an important increase in flp mRNA amount after a downshift temperature especially at ?20?°C. 相似文献
117.
Saleem A Engström M Wurster S Savola JM Pihlaja K 《Zeitschrift für Naturforschung. C, Journal of biosciences》2002,57(3-4):332-338
Forty-two extracts of folk medicinal plant organs from Pakistan were tested in competition binding assays for their interaction with the specific ligand recognition sites on the human alpha2-adrenoceptor subtypes alpha2A, alpha2B and alpha2C Strong binding of the extracts (40 mg/ml) from Acacia nilotica (L.) Delile leaves (88-98% displacement of radiolabel) and Peganum harmala seeds (89-96% displacement) on three subtypes prompted us to extract these plant materials with 40% and 80% methanol, ethanol, and acetone. The extraction results indicated an absence of alpha2-adrenoceptor binding activity in the stalk of A. nilotica and A. tortils, whereas the leaves of both plants contained activity. The extracts of A. nilotica leaves showed a slight, but consistent, preference for the alpha2C-adrenoceptor, whereas the leaves of A. tortils were slightly more active on the alpha2B subtype. The extract of P. harmala stalks was less active than that of its seeds. The binding activities of A. nilotica leaves and P. harmala seeds were mainly concentrated in the water and 30% methanol fractions and further sub-fractions. In a functional activity assay, the active fractions inhibited epinephrine-stimulated 35S-GTPyS binding, thus indicating a predominantly antagonistic nature of the compounds with alpha2-adrenoceptor affinity in these fractions. Among the known major alkaloids of P. harmala (demissidine, harmaline, harmine, 6-methoxyharmalan, and norharmane), only 6-methoxyharmalan showed moderate affinity (dissociation constant (Ki) of 530 +/- 40 nm for alpha2A subtype). This study is a first systematic attempt towards the discovery of potential drug candidates from these plant materials for treating alpha2-adrenoceptor related diseases. 相似文献
118.
Treatment of tomato seedlings (Lycopersicon esculentum Mill. cv. 63/5 F1) with increasing CdCl2 concentrations in the culture medium resulted in Cd accumulation more important in roots than in leaves. Biomass production
was severely inhibited, even at low Cd concentration. Cd reduced chlorophyll content in leaves and enhanced lipid peroxidation.
An increase in antioxidative enzyme (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase)
activities was more pronounced in leaves than in roots, while catalase activity increased only in roots. In addition, changes
in isoenzyme composition were observed using the non-denaturing polyacrylamid gel electrophoresis. 相似文献
119.
120.
France Bruck Ludovic Belle Chantal Lechanteur Laurence de Leval Muriel Hannon Sophie Dubois Emilie Castermans Stephanie Humblet-Baron Souad Rahmouni Yves Beguin Alexandra Briquet Frédéric Baron 《Cytotherapy》2013,15(3):267-279
Background aimsGraft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation caused by donor T cells reacting against host tissues. Previous studies have suggested that mesenchymal stromal cells (MSCs) could exert potent immunosuppressive effects.MethodsThe ability of human bone marrow derived MSCs to prevent xenogeneic GVHD in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice and in NOD/SCID/interleukin-2Rγ(null) (NSG) mice transplanted with human peripheral blood mononuclear cells (PBMCs) was assessed.ResultsInjection of 200 × 106 human PBMCs intraperitoneally (IP) into sub-lethally (3.0 Gy) irradiated NOD/SCID mice also given anti-asialo GM1 antibodies IP 1 day prior and 8 days after transplantation induced lethal xenogeneic GVHD in all tested mice. Co-injection of 2 × 106 MSCs IP on day 0 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs. Similarly, injection of 30 × 106 human PBMCs IP into sub-lethally (2.5 Gy) irradiated NSG mice induced a lethal xenogeneic GVHD in all tested mice. Injection of 3 × 106 MSCs IP on days 0, 7, 14 and 21 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs.ConclusionsInjection of MSCs did not prevent xenogeneic GVHD in these two humanized mice models. 相似文献