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排序方式: 共有240条查询结果,搜索用时 31 毫秒
171.
172.
Suspension-cultured rose ( Rosa damascena Mill. cv. Gloire de Guilan) cells irradiated with UV-C (254 nm. 558 J m−2 ) showed a transient production of H2 O2 as measured by chemiluminescence of luminol in the presence of peroxidase (EC 1.1 1.1.7). The peak concentration of H2 O2 , which occurred at about 60–90 min after irradiation, was 8–9 μ M . The time course for the appearance of H2 O2 matched that for UV–induced K+ efflux. Treatments that inhibited the UV-induced efflux of K+ , including heat and overnight incubation with cycloheximide and diethylmaleate, also inhibited the appearance of H2 O2 . The converse was not always true, since catalase (EC 1.11.1.6. and salicylhydroxamic acid, which inhibited luminescence, did not stop K+ efflux. We conclude that H2 O2 synthesis depends on K+ efflux. Because H2 .O2 in the extracellular space is required for lignin synthesis in many plant tissues, we suggest that the UV–stimulated production of H2 O2 is an integral part of a defensive lignin synthesis. 相似文献
173.
Current drug-susceptibility tests used routinely in clinical laboratories sometimes fail to identify strains of Staphylococcus aureus with reduced susceptibility to vancomycin. To solve this problem, we have developed a more sensitive and rapid method that measures bacterial metabolic activity by a chemiluminescence-based technique. This method is able to discriminate such strains from vancomycin-susceptible S. aureus with a sensitivity and specificity of > 95%. This rapid and reliable method appears to be promising for detection of vancomycin-intermediate S. aureus strains in clinical laboratories, and may supersede classical susceptibility testing. 相似文献
174.
Combinatorial selection of a RNA thioaptamer that binds to Venezuelan equine encephalitis virus capsid protein 总被引:2,自引:0,他引:2
A phosphorothioate RNA aptamer (thioaptamer) targeting the capsid protein of Venezuelan equine encephalitis virus (VEEV) was isolated by in vitro combinatorial selection. The selected thioaptamer had a strong binding affinity (approximately 7nM) and high specificity for the target protein. For the binding to the protein, the overall tertiary structure of the thioaptamer is required. We introduce two theoretical methods to examine the effect of phosphorothioate modification on the enhancement of binding affinity and one experimental method to examine the nature of the multiple bands of thioaptamer in a native gel. 相似文献
175.
HRP-HBVDNA探针在临检应用中的研究 总被引:2,自引:0,他引:2
本文介绍了一种简便的检测血清HBVDNA的方法。参照Renz等人的标记方法,构建了直接酶标HRP HBVDNA探针。此探针经与固定在硝酸纤维素滤膜上的血清靶DNA杂交后,可通过化学发光自显影检测技术观察结果。敏感度可检测0-1pg靶DNA,相当于同位素探针的灵敏度。对63份HBsAgHBeAg和Anti HBcELISA阳性血清以及24份HBsAgAnti HBc阳性,HbeAg阴性血清用HRP HBVDNA探针进行检测,结果探针HBVDNA阳性率分别为100%(63)和58%(14);对50份HBsAg,ELISA阴性和ALT正常的血清,探针HBVDNA全部阴性。实验结果表明本方法具有很大的推广应用价值。 相似文献
176.
Xiangdong You Michael J. Arrowood Marisa Lejkowski Longti Xie Raymond F. Schinazi Jan R. Mead 《FEMS microbiology letters》1996,136(3):251-256
Abstract A chemiluminescence immunoassay (CLIA) was developed to detect Cryptosporidium parvum growth in Madin-Darby canine kidney (MDCK) cell cultures. Optimal results were obtained when MDCK cells were plated at a density of 1 × 104 cells/well (96-well plate) and maintained as a monolayer for 4 days prior to infection with 2 × 104 parasites/well. Two compounds (paromomycin and maduramicin) were evaluated and shown to have selective activity against C. parvum in a dose-dependent manner. There was excellent correlation between CLIA and immunofluorescence assay when assessing anti- C. parvum agents in MDCK cells. CLIA offers advantages over conventional enzyme-linked immunosorbent assay and immunofluorescence assay methods in that it is more sensitive and efficient. The combination of CLIA and MDCK culture provides an efficient tool for evaluating potential anti-cryptosporidial compounds prior to testing in animal models. 相似文献
177.
Yumiko Yoshiki Takashi Kahara Kazuyoshi Okubo Kiharu Igarashi Kazuhiko Yotsuhashi 《Luminescence》1996,11(3):131-136
The photon emission (chemiluminescence; CL) of catechin in the presence of active oxygen species (hydrogen peroxide, hydroxyl radical tert-butyl hydroperoxide and tert-butyl oxyl radical) and acetaldehyde was confirmed to occur non-enzymatically at room temperature in aqueous neutral conditions. The CL intensity [P] in the presence of active oxygen species (X), catalytic species (Y) and receptors (Z) is predicted by [P] = k [X] [Y] [Z]. The calculated photon constants (k) of 8 catechins and gallic acid were 8.23 × 106 M−2 s−1 counts ((−)-epigallocatechin), 2.78 × 106 ((−)-epigallocatechin gallate), 4.66 × 105 ((−)-gallocatechin gallate), 4.36 × 105 ((−)-gallocatechin), 2.70 × 105 ((−)-epicatechin), 6.44 × 104 ((−)-catechin), 5.85 × 104 ((−)-epicatechin gallate), 4.78 × 104 (gallic acid) and 3.54 × 104 ((−)-catechin gallate), respectively. The system of active oxygen species, catalytic species and receptors is proposed to be a scavenging mechanism for active oxygen species. In the presence of acetaldehyde, (−)-epigallocatechin (maximum k value among catechins tested) reacted with tert-BuOOH to form tert-BuOH as determined by HPLC analysis. 相似文献
178.
Aim
Resveratrol (RES) is a well-known antioxidant, yet in combination with other antioxidant vitamins, it was found to be more effective than any of these antioxidants alone. Present work aims to compare the antioxidant actions of resveratrol with and without vitamin C following delivery as liposomes tested using chemical and cellular antioxidative test systems.Main methods
Liposomes were prepared by the thin film hydration method and characterised for percent drug entrapment (PDE), Z-average mean size (nm), polydispersity index (PDI) and zeta potential. Antioxidative capacity was determined by studying the inhibition of AAPH induced luminol enhanced chemiluminescence and inhibition of ROS production in isolated blood leukocytes. Intracellular oxygen-derived radicals were measured using flow cytometry with buffy coats (BC) and human umbilical vein endothelial cells using H2DCF-DA dye.Key findings
Particle size varied from 134.2 ± 0.265 nm to 103.3 ± 1.687 nm; PDI ≤ 0.3; zeta potential values were greater than − 30 mV and PDE ≥ 80%. Radical scavenging effect was enhanced with liposomal systems; oxidative burst reaction in BC was inhibited by liposomal formulations, with the effect slightly enhanced in presence of vitamin C. Reduction in reactive oxygen species (ROS) production during spontaneous oxidative burst of BC and incubation of HUVECs with H2O2 further intensified the antioxidative effects of pure RES and liposomal formulations.Significance
The present work clearly shows that the antioxidative effects of resveratrol loaded into liposomes are more pronounced when compared to pure resveratrol. Liposomal resveratrol is even active within the intracellular compartments as RES could effectively quench the intracellular accumulation of ROS. 相似文献179.
为了提高人睫状神经营养因子(CNTF)的生物学活性,用PCR方法获取N端缺失14个氨基酸的CNTF基因片段,经酶切鉴定、核酸测序证实突变体的核苷酸序列,将其重组至表达质粒pBV220,构建了CNTF突变体表达载体pBV-CNTFΔ.用SDS-PAGE测定其表达水平,鸡胚背根节无血清培养法检测表达蛋白的生物学活性.结果表明,pBV-CNTFΔ能表达生物学活性高于天然CNTF的约26kD蛋白质,表达水平达30%.为今后通过基因工程方法获得CNTF突变体,从而制备高效的CNTF制剂创造了条件. 相似文献
180.
应用RT-PCR检测基因的体外转录活性 总被引:3,自引:0,他引:3
体外转录分析已广泛应用于分子生物学领域.由于体外转录所产生的RNA的量极少,需有灵敏的方法检测生成的RNA.本研究发展了一种基于RT-PCR技术鉴定体外转录产物的方法.将待研究基因的启动区与任何一段已知的含转录起始位点的编码序列相连,制备成体外转录的模板.体外转录后,用DNaseⅠ将DNA模板完全降解;生成的RNA经反转录合成cDNA;再以cDNA为模板,用相应的引物进行PCR扩增,产物用琼脂糖凝胶电泳检测.该法灵敏度高,操作简便,无需同位素,且体外转录模板制备方便.还可结合其他技术,如Southern印迹分析,能获得更高的灵敏度. 相似文献