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111.
Geeta R Ramnath RL Rao HS Chandra V 《Biochemical and biophysical research communications》2008,373(2):258-264
We report the generation of functional dopaminergic neurons from human embryonic stem cells (hESCs) using a growth factor mediated multistep EB protocol and its therapeutic effects in vivo. Embryoid bodies (EBs) were cultured in insulin-transferrin-selenium fibronectin (ITSFn) media for the selection of neural precursor cells (NPC). The selected cells on exposure to N2 media supplemented with EGF, bFGF initially aggregated to generate spontaneous free floating neurospheres and on exposure to signaling molecules Shh and FGF-8 differentiated into dopaminergic neurons (40% TH+ cells/total neurons). The differentiated NPC expressed dopaminergic specific markers both at cellular and molecular levels. They secreted detectable levels of dopamine into the culture supernatant. The most unique feature of our protocol is the generation of free floating neurospheres which can be expanded for a longer period without losing their capability to differentiate into DA neurons. Further, transplantation of NPCs into the substantia nigra of 6-OHDA lesioned rat model of Parkinson’s disease elicited significant reversal of lesion induced motor deficits which was sustained upto the end of 1 year long study period. Immunohistochemical studies of the grafted area one year post transplantation revealed that transplanted hESC derived neural precursor cells survived, integrated in vivo and differentiated into dopaminergic neurons without teratoma formation.In summary, our results encourage the potential use of hESC derived dopaminergic neurons for future clinical application in Parkinson’s disease. 相似文献
112.
Larvicidal activity of Acacia nilotica extracts and isolation of D-pinitol--a bioactive carbohydrate
Chaubal R Pawar PV Hebbalkar GD Tungikar VB Puranik VG Deshpande VH Deshpande NR 《化学与生物多样性》2005,2(5):684-688
A low-molecular-weight, sugar-like compound other than glucose, fructose, sucrose, or myo-inositol showing lipophilic nature was isolated from the EtOH extract of Acacia nilotica. The structure of the compound was determined by spectral methods. This alicyclic polyalcohol was found to be D-pinitol (= 3-O-methyl-D-chiro-inositol; 1). The configuration of the compound was confirmed by single-crystal X-ray analysis. The compound 1 is known from Soybean, Australian mangroves, Fagonia indica, Arachis hypogaea, etc., but we have isolated this compound for the first time from the aerial parts of A. nilotica. Very few references have been cited for compound 1 for its entomological activity, and there are no reports on mosquitoes. Therefore, the crude extracts of A. nilotica were tested for its biological activity against mosquito larvae. Acetone extract at 500-ppm concentration showed chronic toxicity against Aedes aegypti and Culex quinquefasciatus IVth instar mosquito larvae. Such a biological activity has been observed for the first time for this plant. This study could be a stepping stone to a solution for destroying larval species as well as consumption of such a widely grown, problem weed, A. nilotica. This larvicidal agent, since it is derived from plant, is eco-friendly, cost effective, non-hazardous to non-target organisms and would be safe unlike commercially available insecticides. 相似文献
113.
Mallotus roxburghianus is used in the traditional medicine in North-Eastern India, but previously no work has been done on the identification of bioactive compounds. Two new compounds, 3-(1-C-beta-D-glucopyranosyl)-2,6-dihydroxy-5-methoxybenzoic acid (6) and 2,4,8,9,10-pentahydroxy-3,7-dimethoxyanthracene-6-O-beta-D-rhamnopyranoside (7) together with beta-sitosterol (1), stigmasterol (2), betulinic acid (3), 4-hydroxybenzoic acid (4), beta-sitosterol-beta-D-glucoside (5), and bergenin (8) were isolated and identified from the leaves of M. roxburghianus. The chloroform soluble portion of the alcoholic extract of leaf, and compounds 3, 6, 7, and 8 exhibited encouraging antioxidant activities. 相似文献
114.
The lateral geniculate nuclear complex of albino rats was investigated with respect to the development of neurotransmitters/neuromodulators
such as glutamate, cholecystokinin and vasoactive intestinal polypeptide at gestational day 18, various postnatal age periods
and in the adult using immunohistochemical methods. The study shows the unequivocal presence of and the sequential changes
in the profile of glutamate while cholecystokinin and vasoactive intestinal polypeptide are not demonstrable at any of the
age periods. Glutamate is seen both in the cells and fibres from 40 postnatal day onwards and immunoreactivity is more intense
in the adult. The findings are discussed with relevance to the role of neurotransmitters in development. 相似文献
115.
A significant improvement in the production of l-ribulose from inexpensive and commercially available starting materials, L-arabinose and sodium aluminate, is demonstrated. This has facilitated expeditious access to gram-scale quantities of L-ribulofuranoside derivatives. 相似文献
116.
117.
The study was conducted on Punjabi Arora girls (n = 159) and their mothers to see the phenomenon of secular trend in stature and age at menarche. An increase in stature and decrease in age at menarche was reported when the data of daughters was compared with that of their mothers thereby indicating secular trend in these two parameters. Better living conditions, improved nutrition and medical facilities, changes in environmental and socio-economic factors may account for increase in stature and early biological maturation. 相似文献
118.
119.
Human apolipoprotein A-I and A-I mimetic peptides: potential for atherosclerosis reversal 总被引:1,自引:0,他引:1
Navab M Anantharamaiah GM Reddy ST Van Lenten BJ Datta G Garber D Fogelman AM 《Current opinion in lipidology》2004,15(6):645-649
PURPOSE OF REVIEW: Recent publications related to the potential use of apolipoprotein (apo)A-I and apoA-I mimetic peptides in the treatment of atherosclerosis are reviewed. RECENT FINDINGS: A preliminary report indicating that infusion of apoA-IMilano into humans once weekly for 5 weeks caused a significant decrease in coronary artery atheroma volume has sparked great interest in the potential therapeutic use of apoA-I. Recent studies have revealed that HDL quality (e.g. HDL apolipoprotein and lipid content, including oxidized lipids, particle size and electrophoretic mobility, associated enzymatic activities, inflammatory/anti-inflammatory properties, and ability to promote cholesterol efflux) may be more important than HDL-cholesterol levels. Therefore, when developing new strategies to raise HDL-cholesterol concentrations by interfering with HDL metabolism, one must consider the quality of the resulting HDL. In animal models, raising HDL-cholesterol levels by administering oral phospholipids improved both the quantity and quality of HDL and was associated with lesion regression. An apoA-I mimetic peptide, namely 4F synthesized from D-amino acids (D-4F), administered orally to mice did not raise HDL-cholesterol concentrations but promoted the formation of pre-beta HDL containing increased paraoxonase activity, resulting in significant improvements in HDL's anti-inflammatory properties and ability to promote cholesterol efflux from macrophages in vitro. Oral D-4F also promoted reverse cholesterol efflux from macrophages in vivo. SUMMARY: The quality of HDL may be more important than HDL-cholesterol levels. ApoA-I and apoA-I mimetic peptides appear to have significant therapeutic potential in atherosclerosis. 相似文献
120.
John Chen Nuria Carpena Nuria Quiles-Puchalt Geeta Ram Richard P Novick José R Penadés 《The ISME journal》2015,9(5):1260-1263
Bacteriophage-mediated horizontal gene transfer is one of the primary driving forces of bacterial evolution. The pac-type phages are generally thought to facilitate most of the phage-mediated gene transfer between closely related bacteria, including that of mobile genetic elements-encoded virulence genes. In this study, we report that staphylococcal cos-type phages transferred the Staphylococcus aureus pathogenicity island SaPIbov5 to non-aureus staphylococcal species and also to different genera. Our results describe the first intra- and intergeneric transfer of a pathogenicity island by a cos phage, and highlight a gene transfer mechanism that may have important implications for pathogen evolution.Classically, transducing phages use the pac site-headful system for DNA packaging. Packaging is initiated on concatemeric post-replicative DNA by terminase cleavage at the sequence-specific pac site, a genome slightly longer than unit length is packaged, and packaging is completed by non-sequence-specific cleavage (reviewed in Rao and Feiss, 2008). Generalized transduction results from the initiation of packaging at pac site homologs in host chromosomal or plasmid DNA, and typically represents ∼1% of the total number of phage particles. In the alternative cos site mechanism packaging is also initiated on concatemeric post-replicative DNA by terminase cleavage at a sequence-specific (cos) site. Here, however, packaging is completed by terminase cleavage at the next cos site, generating a precise monomer with the cohesive termini used for subsequent circularization (Rao and Feiss, 2008). Although cos site homologs may exist in host DNA, it is exceedingly rare that two such sites would be appropriately spaced. Consequently, cos phages, of which lambda is the prototype, do not engage in generalized transduction. For this reason, cos-site phages have been preferred for possible phage therapy, since they would not introduce adventitious host DNA into target organisms.The Staphylococcus aureus pathogenicity islands (SaPIs) are the best-characterized members of the phage-inducible chromosomal island family of mobile genetic elements (MGEs; Novick et al., 2010). SaPIs are ∼15 kb mobile elements that encode virulence factors and are parasitic on specific temperate (helper) phages. Helper phage proteins are required to lift their repression (Tormo-Más et al., 2010, 2013), thereby initiating their excision, circularization and replication. Phage-induced lysis releases vast numbers of infectious SaPI particles, resulting in high frequencies of transfer. Most SaPI helper phages identified to date are pac phages, and many well-studied SaPIs are packaged by the headful mechanism (Ruzin et al., 2001; Ubeda et al., 2007). Recently, we have reported that some SaPIs, of which the prototype is SaPIbov5 (Viana et al., 2010), carry phage cos sequences in their genomes, and can be efficiently packaged and transferred by cos phages to S. aureus strains at high frequencies (Quiles-Puchalt et al., 2014). Here we show that this transfer extends to non-aureus staphylococci and to Listeria monocytogenes.Since the pac phages transfer SaPIs to non-aureus staphylococci and to the Gram-positive pathogen Listeria monocytogenes (Maiques et al., 2007; Chen and Novick, 2009), we reasoned that cos phages might also be capable of intra- and intergeneric transfer. We tested this with SaPIbov5, into which we had previously inserted a tetracycline resistance (tetM) marker to enable selection, and with lysogens of two helper cos phages, φ12 and φSLT, carrying SaPIbov5 (strains JP11010 and JP11194, respectively; Supplementary Table 1). The prophages in these strains were induced with mitomycin C, and the resulting lysates were adjusted to 1 μg ml−1 DNase I and RNase A, filter sterilized (0.2 μm pore), and tested for SaPI transfer with tetracycline selection, as previously described (Ubeda et al., 2008). To test for trans-specific or trans-generic transduction, coagulase-negative staphylococci species and L. monocytogenes strains were used as recipients for SaPIbov5 transfer, respectively, as previously described (Maiques et al., 2007; Chen and Novick, 2009). As shown in Figure 1 and Supplementary Table 2). In contrast, deletion of the SaPIbov5 cos site (strains JP11229 and JP11230) did not affect SaPI replication (Supplementary Figure 1), but completely eliminated SaPIbov5 transfer (Supplementary Table 2). The TerS protein is essential for φ12 and SaPIbov5 DNA packaging, but not for phage-mediated lysis (Quiles-Puchalt et al., 2014). As expected, this mutation abolished SaPIbov5 transfer (Open in a separate windowFigure 1(a) Map of SaPIbov5. Arrows represent the localization and orientation of ORFs greater than 50 amino acids in length. Rectangles represent the position of the ori (in purple) or cos (in red) sites. Positions of different primers described in the text are shown. (b) Amplimers generated for detection of SaPIbov5 in the different recipient strains. Supplementary Table 2 lists the sequence of the different primers used. The element was detected in S. epidermidis JP829 (Se-1), S. epidermidis JP830 (Se-2), L. monocytogenes SK1351 (Lm-1), L. monocytogenes EGDe (Lm-2), S. xylosus C2a (Sx) and S. aureus JP4226 (Sa).
Open in a separate windowAbbreviation: SAPI, Staphylococcus aureus pathogenicity island.aThe means of results from three independent experiments are shown. Variation was within ±5% in all cases.bNo. of transductants per ml induced culture.Because plaque formation is commonly used to determine phage host range, we next determined the ability of phages φ12 and φSLT to parasitize and form plaques on S. xylosus, S. epidermidis and L. monocytogenes strains. As shown in Supplementary Figure 2, phages φ12 and φSLT can parasitize and form plaques on their normal S. aureus hosts, but are completely unable to lyse the non-aureus strains. Therefore, as previously observed with pac phages (Chen and Novick, 2009), these results indicate that the overall host range of a cos phage may also be much wider if it includes infection without plaque formation.Previous studies have demonstrated pac phage-mediated transfer of MGEs between S. aureus and other bacterial species (Maiques et al., 2007; Chen and Novick, 2009; Uchiyama et al., 2014); however, no previous studies have described the natural intra- or intergeneric transfer of pathogenicity islands by cos phages. As bacterial pathogens become increasingly antibiotic resistant, lytic and poorly transducing phages, such as cos phages, have been proposed for phage therapy, on the grounds that they would not introduce adventitious host DNA into target organisms and that the phages are so restricted in host range that the resulting progeny are harmless and will not result in dysbiosis of human bacterial flora. Because plaque formation was once thought to determine the host range of a phage, the evolutionary impact of phages on bacterial strains they can transduce, but are unable to parasitize, has remained an unrecognized aspect of phage biology and pathogen evolution. Our results add to the recently recognized concept of ‘silent transfer'' of pathogenicity factors carried by MGEs (Maiques et al., 2007; Chen and Novick, 2009) by phages that cannot grow on the target organism. They extend this capability to cos phages, which have hitherto been unrecognized as mediators of natural genetic transfer.The potential for gene transfer of MGEs by this mechanism is limited by the ability of cos phages to adsorb and inject DNA into recipient strains, and also by the presence of suitable attachment sites in recipient genomes. However, since different bacterial genera express wall teichoic acid with similar structures, which can act as bacteriophage receptors governing the routes of horizontal gene transfer between major bacterial pathogens, horizontal gene transfer even across long phylogenetic distances is possible (Winstel et al., 2013). In addition, our previous results also demonstrated that the SaPI integrases have much lower sequence specificity than other typical integrases, and SaPIs readily integrate into alternative sites in the absence of the cognate attC site, such that any bacterium that can adsorb SaPI helper phage is a potential recipient (Chen and Novick, 2009). Thus, we anticipate that cos phages can have an important role in spreading MGEs carrying virulence and resistance genes. We also predict that cos sites will be found on many other MGEs, enabling cos phage-mediated transfer of any such element that can generate post-replicative concatemeric DNA. 相似文献
Table 1
Intra- and intergeneric SaPIbov5 transferaDonor strain | |||
---|---|---|---|
Phage | SaPI | Recipient strain | SaPI titreb |
φ12 | SaPIbov5 | S. aureus JP4226 | 8.3 × 104 |
S. epidermidis JP829 | 2.4 × 104 | ||
S. epidermidis JP830 | 4.7 × 104 | ||
L. monocytogenes SK1351 | 6.6 × 103 | ||
L. monocytogenes EGDe | 2.1 × 104 | ||
S. xylosus C2a | 7.1 × 104 | ||
φ12 | SaPIbov5 Δcos | S. aureus JP4226 | <10 |
S. epidermidis JP829 | <10 | ||
S. epidermidis JP830 | <10 | ||
L. monocytogenes SK1351 | <10 | ||
L. monocytogenes EGDe | <10 | ||
S. xylosus C2a | <10 | ||
φ12 ΔterS | SaPIbov5 | S. aureus JP4226 | <10 |
S. epidermidis JP829 | <10 | ||
S. epidermidis JP830 | <10 | ||
L. monocytogenes SK1351 | <10 | ||
L. monocytogenes EGDe | <10 | ||
S. xylosus C2a | <10 | ||
φSLT | SaPIbov5 | S. aureus JP4226 | 4.1 × 103 |
S. epidermidis JP829 | 1.1 × 103 | ||
S. epidermidis JP830 | 2.1 × 103 | ||
L. monocytogenes SK1351 | 3.6 × 102 | ||
L. monocytogenes EGDe | 3.1 × 103 | ||
S. xylosus C2a | 4.0 × 103 | ||
φSLT | SaPIbov5 Δcos | S. aureus JP4226 | <10 |
S. epidermidis JP829 | <10 | ||
S. epidermidis JP830 | <10 | ||
L. monocytogenes SK1351 | <10 | ||
L. monocytogenes EGDe | <10 | ||
S. xylosus C2a | <10 |