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71.
22 indole alkaloids were isolated from the stem bark of Nigerian Rauwolfia vomitoria and 20 characterized. The alkaloids comprised E-seco heteroyohimbine, sarpagan, dihydroindole, yohimbine and heteroyohimbine types. The biosynthetic relationship of the alkaloids is discussed. 相似文献
72.
Renisio JG Cosquer S Cherrak I El Antri S Mauffret O Fermandjian S 《Nucleic acids research》2005,33(6):1970-1981
The integration of the human immunodeficiency virus type 1 DNA into the host cell genome is catalysed by the viral integrase (IN). The reaction consists of a 3'-processing [dinucleotide released from each 3' end of the viral long terminal repeat (LTR)] followed by a strand transfer (insertion of the viral genome into the human chromosome). A 17 base pair oligonucleotide d(GGAAAATCTCTAGCAGT), d(ACTGCTAGAGATTTTCC) reproducing the U5-LTR extremity of viral DNA that contains the IN attachment site was analysed by NMR using the classical NOEs and scalar coupling constants in conjunction with a small set of residual dipolar coupling constants (RDCs) measured at the 13C/15N natural abundance. The combination of these two types of parameters in calculations significantly improved the DNA structure determination. The well-known features of A-tracts were clearly identified by RDCs in the first part of the molecule. The binding/cleavage site at the viral DNA end is distinguishable by a loss of regular base stacking and a distorted minor groove that can aid its specific recognition by IN. 相似文献
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74.
Subcellular distribution of 2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) in desheathed, saline perfused cat sciatic nerve is reported. CNPase specific activity was enriched in the total particulate (P2) fraction and was low in the soluble (S2) fraction. “Light-myelin” floating above the 0.60 M sucrose phase had the highest CNPase activity, 2.5-fold over the crude homogenate (CH). By contrast, enzyme activity in “heavy myelin” floating above the 0.85 M sucrose interface was equal to that of the CH and accounted for only 12% of total activity. CNPase activity in the membranes floating above the 0.25 and 0.60 and 0.85 M sucrose phases comprised nearly 70% of the total CNPase activity. The “light myelin” fraction floating above the 0.60 M sucrose accounted for approx. 51% of the total CNPase activity. SDS-PAGE of membranes individually harvested from above the 0.25 and 0.60 and 0.85 M sucrose phases revealed the presence of myelin-specific proteins (P0, P1; and P2). Electron microscope examination demonstrated the presence of myelin in each membrane fraction. The results of this study show that the majority of CNPase activity is associated with “light myelin” in cat peripheral nerve. 相似文献
75.
Nareshwaran Gnanasegaran Vijayendran Govindasamy Sabri Musa Noor Hayaty Abu Kasim 《Cytotechnology》2016,68(2):343-353
Among the debilitating diseases, neurological related diseases are the most challenging ones to be treated using cell replacement therapies. Recently, dental pulp stem cells (SHED) were found to be most suitable cell choice for neurological related diseases as evidenced with many preclinical studies. To enhance the neurological potential of SHED, we recapitulated one of the pharmacological therapeutic tools in cell replacement treatment, we pre-conditioned dental pulp stem cells (SHED) with culture medium of ReNCell VM, an immortalized neuron progenitor cell, prior to neurogenesis induction and investigated whether this practice enhances their neurogenesis potential especially towards dopaminergic neurons. We hypothesed that the integration of pharmacological practices such as co-administration of various drugs, a wide range of doses and duration as well as pre-conditioning into cell replacement may enhance the efficacy of stem cell therapy. In particular, pre-conditioning is shown to be involved in the protective effect from some membrano-tropic drugs, thereby improving the resistance of cell structures and homing capabilities. We found that cells pre-treated with ReNCell VM conditioned medium displayed bipolar structures with extensive branches resembling putative dopaminergic neurons as compared to non-treated cells. Furthermore, many neuronal related markers such as NES, NR4A2, MSI1, and TH were highly expressed (fold changes > 2; p < 0.05) in pre-treated cells. Similar observations were detected at the protein level. The results demonstrate for the first time that SHED pre-conditioning enhances neurological potential and we suggest that cells should be primed to their respective environment prior to transplantation. 相似文献
76.
Andrew I. Soiefer Angelo Moretto Peter S. Spencer Mohammad I. Sabri 《Neurochemical research》1988,13(12):1169-1173
Vinca alkaloids were used to study the role of retrograde axon transport (RT) in activating neuron perikaryal repair response to nerve transection. Mouse lumbar dorsal root ganglia (DRG) (L4-L6) were excised 48 hours after unilateral transection of the sciatic nerve and ornithine decarboxylase (ODC) activity determined. ODC activity in DRG ipsilateral to nerve transection was increased 10–20 fold over contralateral values. Typical ODC activities in ipsilateral and contralateral DRG samples were 6.18±1.4 and 0.31±0.09 pmol14CO2 released/h/3DRG, respectively. Systemic administration of single doses of either vincristine (1 mg/kg) or vinblastine (5 mg/kg) immediately prior to axotomy attenuated ODC induction in ipsilateral DRG by 39% and 47%, respectively. A direct inhibition of ODC activity in the DRG appears unlikely since only high concentrations of vinblastine (0.5–1.0 mM) were able to inhibit ODC activity in vitro. We suggest vinca alkaloids inhibit ODC induction as a consequence of distupting retrograde axonal transport. Interruption of this intracellular communication mechanism may be etiologically linked to the distal axon degeneration which follows repetitive exposure to vinca alkaloids and other agents that induce toxic axonal neuropathy. 相似文献
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79.
Ponnarasy Ganasen Maksudur Rahman Khan M. Abul Kalam Mohd Sabri Mahmud 《Bioprocess and biosystems engineering》2014,37(11):2353-2359
This paper demonstrates Pseudomonas cepacia lipase catalyzed hydrolysis of p-nitrophenyl palmitate under irradiation of light with wavelengths of 250–750 nm. The reaction follows Michaelis–Menten Kinetics and the light irradiation increases the overall rate of hydrolysis. Using Lineweaver–Burk plot K M and V max values for the reaction in presence of light are found to be 39.07 and 66.67 mM/min/g, respectively; while for the same reaction under dark condition, the values are 7.08 and 10.21 mM/min/g. The linear form of enzyme dependent rate of reaction confirms that no mass-transfer limitations are present and the reaction is a kinetically controlled enzymatic reaction. 相似文献
80.
Despite the constantly increasing need for new antimicrobial agents, antibiotic drug discovery and development seem to have
greatly decelerated in recent years. Presented with the significant problem of advancing antimicrobial resistance, the global
scientific community has attempted to find alternative solutions; one of the most promising ones is the evaluation and use
of old antibiotic compounds. A number of old antibiotic compounds, such as aminoglycosides, chloramphenicol, and tetracycline,
are re-emerging as valuable alternatives for the treatment of difficult-to-treat infections. This study examined the in vitro
potency for biofilm formation of five isolates (Klebsiella sp., Pseudomonas aeruginosa, Achromobacter sp., Klebsiella pneumoniae, and Bacillus pumilis) and the effects of antibiotics on these biofilms. Furthermore the quantitative analysis of planktonic, loosely attached
cells, and their susceptibility to antibiotics was also determined. Twitching motility was observed to determine any effect
in the biofilm forming capability of the isolates. All the isolates tested were efficient biofilm-forming strains in the polypropylene
and borosilicate test tubes. Standard bacterial enumeration technique and CV staining produced equivalent results both in
biofilm and planktonic assays. The biofilm formation of all the strains was affected in the presence of tetracycline or chloramphenicol.
Highly significant decrease (P < 0.01) in biofilm formation was observed by treatment with chloramphenicol compared to tetracycline. In addition, the two
antibiotics also affected adversely the planktonic and loosely attached cells of all isolates. Thus, testing the effects of
older antibiotics on biofilms may supply useful information in addition to standard in vitro testing, particularly in diseases
where biofilm formation is involved in the pathogenesis. 相似文献