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311.
The antifungal activity of methanolic crude extracts of Acorus calamus, Tinospora cordifolia and Celestrus paniculatus was investigated against Alternaria solani, Curvularia lunata, Fusarium sp., Bipolaris sp. and Helminthosporium sp. at different concentrations (1000, 2000, 3000, 4000 and 5000 μg/ml). At 5000 μg/ml, crude extract of T. cordifolia is found to be highly effective against Helminthosporium sp. followed by A. calamus against A. solani. On the other hand, at 5000 μg/ml, C. paniculatus showed better activity against A. solani and Helminthosporium followed by A. calamus against A. solani at 4000 μg/ml. At 5000 μg/ml, all the three crude extracts showed least activity against fungus C. lunata and Fusarium sp. except A. calamus that showed better activity against C. lunata. The increase in the production of phenolic acid in the extract can be correlated with the induction of resistance in treated plants against phytopathogenic fungi. High-performance liquid chromatography analysis of the crude extract of medicinal plants showed six different phenolic acids (benzoic acid, cinnamic acid, caffeic acid, ferulic acid, gallic acid and tannic acid) present in varying amounts. The results of the study provide scientific basis for the use of the plant extract in the future development as antioxidant, antibacterial, antifungal and anti-inflammatory agent.  相似文献   
312.
The molecular structure of the DNA double helix has been known for 60 years, but we remain surprisingly ignorant of the balance of forces that determine its mechanical properties. The DNA double helix is among the stiffest of all biopolymers, but neither theory nor experiment has provided a coherent understanding of the relative roles of attractive base stacking forces and repulsive electrostatic forces creating this stiffness. To gain insight, we have created a family of double-helical DNA-like polymers where one of the four normal bases is replaced with various cationic, anionic or neutral analogs. We apply DNA ligase-catalyzed cyclization kinetics experiments to measure the bending and twisting flexibilities of these polymers under low salt conditions. Interestingly, we show that these modifications alter DNA bending stiffness by only 20%, but have much stronger (5-fold) effects on twist flexibility. We suggest that rather than modifying DNA stiffness through a mechanism easily interpretable as electrostatic, the more dominant effect of neutral and charged base modifications is their ability to drive transitions to helical conformations different from canonical B-form DNA.  相似文献   
313.
Novel cisplatin analogs dichloro[4,4′-bis(4,4,4-trifluorobutyl)-2,2′-bipyridine]platinum (1) and fac-tricarbonylchloro[4,4′-bis(4,4,4-trifluorobutyl)-2,2′-bipyridine]rhenium (3) were synthesized and evaluated for their cytotoxicity. While 3 was not cytotoxic, 1 was 14 to 125 times more lethal than cisplatin in breast, prostate, and lung cancer cell lines. Compound 1 was able to induce apoptosis and the presence of the platinum atom was essential to its function as a cytotoxin.  相似文献   
314.
The nuclear hormone receptor estrogen receptor α (ERα) mediates the actions of estrogens in target cells and is a master regulator of the gene expression and proliferative programs of breast cancer cells. The presence of ERα in breast cancer cells is crucial for the effectiveness of endocrine therapies, and its loss is a hallmark of endocrine-insensitive breast tumors. However, the molecular mechanisms underlying the regulation of the cellular levels of ERα are not fully understood. Our findings reveal a unique cellular pathway involving the p38 mitogen-activated protein kinase (p38MAPK)-mediated phosphorylation of ERα at Ser-294 that specifies its turnover by the SCF(Skp2) proteasome complex. Consistently, we observed an inverse relationship between ERα and Skp2 or active p38MAPK in breast cancer cell lines and human tumors. ERα regulation by Skp2 was cell cycle stage dependent and critical for promoting the mitogenic effects of estradiol via ERα. Interestingly, by the knockdown of Skp2 or the inhibition of p38MAPK, we restored functional ERα protein levels and the control of gene expression and proliferation by estrogen and antiestrogen in ERα-negative breast cancer cells. Our findings highlight a novel pathway with therapeutic potential for restoring ERα and the responsiveness to endocrine therapy in some endocrine-insensitive ERα-negative breast cancers.  相似文献   
315.
Cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with two new unsymmetrical ligands, isatin salicylaldehyde oxalic acid dihydrazide (isodh) and isatin salicylaldehyde malonic acid dihydrazide (ismdh) were synthesized and characterized by elemental analyses, electrical conductance, magnetic moments, electronic, NMR, ESR and IR spectral studies. The isodh acts as a dibasic tetra dentate ligand bonding through two >C=N-, a deprotonated phenolate and deprotonated indole enolate groups to the metal. The ismdh ligand shows monobasic tetra dentate behaviour in bonding with metal ion through two >C=N-, indole >C=O and a deprotonated phenolate group. The electronic spectral data suggest 4-coordinate square planar geometry for Co(II), Ni(II) and Cu(II) complexes of isodh, whereas, 6-coordinate octahedral structure for the ismdh complexes. The ESR studies also indicate a square planar and distorted octahedral environment around Cu(II) for isodh and ismdh complexes, respectively. Most of the metal complexes show better antifungal activity than the standard and a significant antibacterial activity against various fungi and bacteria.  相似文献   
316.
Sperm motility is an important prerequisite for successful fertilization and is regulated by cyclic AMP activated protein kinase A which phosphorylates flagella proteins like axonemal dynein and initiates motility. Increase in calcium influx reverses this process by dephosphorylation that is mediated by calcineurin. Analyzing the phosphoenriched fractions of spermatozoa lysates from eight normozoospermic-, and asthenozoospermic-samples, respectively, by Nano UPLC-MS(E), the present study investigates the phosphoproteins involved in sperm motility in an attempt to identify the key pathways regulating sperm motility and likely to be altered in spermatozoa of asthenozoospermic individuals. 66 phosphoproteins were differentially regulated in asthenozoospermia. The deregulated proteins comprised predominantly the HSPs, cytoskeletal proteins, proteins associated with the fibrous sheath, and those associated with energy metabolism. EM analysis of these spermatozoa demonstrated significant defects in mitochondria, and fibrous sheath and these defects could be correlated with the altered proteome. Pathway analysis revealed that carbohydrate and energy metabolism, cAMP mediated PKA signaling, PI3K/AKT signaling and pathway regulating actin based motility by Rho were significantly altered indicating that motility in spermatozoa is regulated through the concerted effort of these pathways. The data identified signature molecules that have the potential as biomarkers for diagnosing etiology of asthenozoospermia.  相似文献   
317.
A lipase from the thermophilic isolate Bacillus coagulans BTS-3 was produced and purified. The enzyme was purified 40-fold to homogeneity by ammonium sulfate precipitation and DEAE-Sepharose column chromatography. Its molecular weight was 31 kDa on SDS-PAGE. The purified lipase was immobilized on silica and its binding efficiency was found to be 60%. The enzyme took 60 min to bind maximally onto the support. The pH and temperature optima of immobilized lipase were same as those of the free enzyme, i.e. 8.5 and 55 degrees C, respectively. The immobilized enzyme had shown marked thermostability on the elevated temperatures of 55, 60, 65 and 70 degrees C. The immobilized enzyme was reused for eigth cycles as it retained almost 80% of its activity. The catalytic activity of immobilized enzyme was enhanced in n-hexane and ethanol. The immobilized enzyme when used for esterification of ethanol and propionic acid showed 96% conversion in n-hexane in 12 h at 55 degrees C.  相似文献   
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This paper presents the design and evaluation of an adaptive system sensitive partitioning and load balancing framework for distributed adaptive mesh refinement applications on heterogeneous and dynamic cluster environments. The framework uses system capabilities and current system state to select and tune appropriate partitioning parameters (e.g., partitioning granularity, load per processor) to maximize overall application performance. Furthermore, it uses dynamic load sensing (using NWS) to adapt to the load dynamics in the cluster.  相似文献   
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