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991.
The effects of inorganic phosphate (Pi), the main intracellular membrane permeable anion capable of altering mitochondrial pH gradients (ΔpH), were measured on mitochondrial H2O2 release. As expected, Pi decreased ΔpH and increased the electric membrane potential (ΔΨ). Mitochondrial H2O2 release was stimulated by Pi and also by its structural analogue arsenate. However, acetate, another membrane-permeable anion, did not stimulate mitochondrial H2O2 release. The stimulatory effect promoted by Pi was prevented by CCCP, which decreases transport of Pi across the inner mitochondrial membrane, indicating that Pi must be in the mitochondrial matrix to stimulate H2O2 release. In conclusion, we found that Pi and arsenate stimulate mitochondrial reactive oxygen release, an effect that may contribute towards oxidative stress under conditions such as ischemia/reperfusion, in which high-energy phosphate bonds are hydrolyzed. 相似文献
992.
《Free radical research》2013,47(6):359-369
Spin trapping techniques have been used to detect free radicals generated from the in vitro metabolism by rat liver microsomes of carbon tetrachloride (CCl4) and bromotrichloromethane (BrCCI) under conditions of varying oxygen tension and pH. Dispersions of rat liver microsomes incubated with 12CCl4, 13CCl4 or Br12CCl3, α-phenyl-tert-butyl nitrone (PBN) and NADPH/NADH in a phosphate buffer varying in pH from 6.6 to 8.0 under varying oxygen tensions produced various amounts of four different PBN adducts: PBN-CCl3, PBN-L, PBN-OL and PBN-CO?2 where L is a carbon-centered lipid type radical and LO is an oxygen-centered lipid type radical. The relative amount of PEN-CO; increases with the absence of oxygen. With the use of 31P-NMR in vivo spectroscopy it was possible to detect a pH change from 7.4 to 6.8 in the livers of rats treated with CCl4, or BrCCl3. These results suggest that halocarbon metabolism in biological systems may depend on both oxygen tension as well as pH. 相似文献
993.
Spin-trapping investigators are largely limited by the instability of the radical adducts. Spin trap 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO) forms very stable alkoxyl radical adducts. However, the presence of two chiral centers in the DEPMPO alkoxyl radical adduct results in two diastereomers with distinctive ESR spectra, which complicates the interpretation of the ESR spectra. We have analyzed the high resolution ESR spectra of the DEPMPO/?OCH3 radical adduct. DEPMPO/?OCH3 has been synthesized by the nucleophilic addition of alcohols to DEPMPO. The electron spin resonance (ESR) spectrum of DEPMPO/?OCH3 in oxygen-free methanol solution reveals superhyperfine structure with hyperfine coupling constants as small as 0.3?G. In order to simplify the analysis of the electron spin resonance (ESR) spectrum, we synthesized the DEPMPO/?OCD3 radical adduct. Computer simulation of the DEPMPO/?OCD3 ESR spectrum revealed two diastereomers. Hyperfine coupling constants of γ-protons and 17O from the –OCH3 group were also determined. ESR spectra of DEPMPO/?OCH3 in phosphate buffer have also been characterized. The presence of specific hyperfine couplings from the –OCH3 group can be used for the unambiguous identification of the DEPMPO/?OCH3 radical adducts. We suggest that the analysis of high resolution ESR spectra can be used for the unambiguous characterization of DEPMPO radical adducts. 相似文献
994.
995.
Yasukazu Yoshida Noriko Noguchi Akira Watanabe Yoshihide Iwaki Makoto Yanagisawa Tatsuhiko Kodama 《Free radical research》2013,47(11):1171-1178
With increasing evidence suggesting the involvement of oxidative stress in various disorders and diseases, the role of antioxidants in vivo has received much attention. 2,3-Dihydro-5-hydroxy-2,2-dipentyl-4,6-di- tert -butylbenzofuran (BO-653) was designed, synthesized and has been evaluated as a novel antiatherogenic drug. In order to further understand the action of BO-653 and also radical-scavenging antioxidants in general, the dynamics of inhibition of oxidation by BO-653 were compared with those of the related compounds, 2,3-dihydro-5-hydroxy-2,2-dimethyl-4,6-di- tert -butylbenzofuran (BOB), 2,3-dihydro-5-hydroxy-2,2,4,6-tetramethylbenzofuran (BOM), f -tocopherol and 2,2,5,7,8-pentamethyl-6-chromanol (PMC), aiming specifically at elucidating the effects of substituents and side chain length of the phenolic antioxidants. These five antioxidants exerted substantially the same reactivities toward radicals and antioxidant capacities against lipid peroxidation in organic solution. When compared with di-methyl side chains, the di-pentyl side chains of BO-653 reduced its inter-membrane mobility but exerted less significant effect than the phytyl side chain of f -tocopherol on the efficacy of radical scavenging within the membranes. Di- tert -butyl groups at both ortho-positions made BO-653 and BOB more lipophilic than di-methyl substituents and reduced markedly the reactivity toward Cu(II) and also the synergistic interaction with ascorbate. The results of the present study together with those of the previous work on the effect of substituents on the stabilities of aryloxyl radicals suggest that tert -butyl group is more favorable than methyl group as the substituent at the ortho-positions and that di-pentyl side chains may be superior to a phytyl side chain. 相似文献
996.
The 3‐aminophthalic acid anion is a light emitter in luminol chemiluminescence. In the present study, the chemiluminescence of the 3‐aminophthalic acid anion itself in the presence of hydrogen peroxide–cobalt (II) was studied. The results indicated that 3‐aminophthalic acid anion is highly chemiluminescent in the typical hydrogen peroxide–cobalt (II) system. The peak wavelength of this chemiluminescence and the kinetic profile of the 3‐aminophthalic acid anion–hydrogen peroxide–cobalt (II) reaction showed similarity with that of luminol, but the chemiluminescence of 3‐aminophthalic acid anion had a much lower background signal. In addition, the chemiluminescence mechanism of 3‐aminophthalic acid anion–hydrogen peroxide–cobalt (II) was also discussed and speculated as the interaction between 3‐aminophthalic acid anion and singlet oxygen. 相似文献
997.
摘要 目的:探究Ki67与MR在宫颈癌根治术后宫颈癌淋巴结转移中评估价值的对比。方法:选择2016年1月至2018年1月于我院接受宫颈癌根治术的151例宫颈癌患者,分别对其实施Ki67检测及MRI检测,以病理学检测结果为金标准,计算两种检测方式对宫颈癌淋巴结转移评估的准确度、敏感度、特异度、阳性预测值及阴性预测值,并进行对比分析。结果:检测评估发现,MRI对宫颈癌淋巴结转移评估准确度为31.79 %,灵敏度为46.75 %,特异度为16.22 %,阳性预测值为36.73 %,阴性预测值为22.64 %。Ki67检测对宫颈癌淋巴结转移评估准确度为42.38 %,灵敏度为52.56 %,特异度为31.51 %,阳性预测值为45.05 %,阴性预测值为38.33 %。两种检测方式对比显示Ki67对宫颈癌淋巴结转移具有更高的诊断准确度。结论:3 相比于MRI检测,Ki67对宫颈癌淋巴结转移具有更高的诊断准确度、特异度和阴性预测值,分析其原因与MRI检测受个体因素影响更大有关。 相似文献
998.
Primary hypertrophic osteoarthropathy (PHO) is a rare monogenetic disease that closely mimics hypertrophic osteoarthropathy secondary to pulmonary or other pathology. The study of PHO provides an opportunity to understand both the pathogenesis of hypertrophic osteoarthropathy and the functions of the underlying genes. PHO is characterized by digital clubbing, periostosis and pachydermia. Two genes are known to be related to PHO: SLCO2A1 and HPGD. Here, we identified a recurrent heterozygous guanine-to-adenine transition at the invariant + 1 position of the donor site of intron 7 (c.940 + 1G > A) and a novel heterozygous missense mutation p.Asn534Lys (c.1602C > A) in exon 11 of SLCO2A1 in a Chinese young man with PHO. Identification of a novel genotype in PHO will provide clues to the phenotype–genotype relations and may assist not only in the clinical diagnosis of PHO but also in the interpretation of genetic information used for prenatal diagnosis and genetic counseling. 相似文献
999.
S. Koutaniemi M.P. van Gool M. Juvonen J. Jokela S.W. Hinz H.A. Schols M. Tenkanen 《Journal of biotechnology》2013
Mass spectrometric analysis was used to compare the roles of two acetyl esterases (AE, carbohydrate esterase family CE16) and three acetyl xylan esterases (AXE, families CE1 and CE5) in deacetylation of natural substrates, neutral (linear) and 4-O-methyl glucuronic acid (MeGlcA) substituted xylooligosaccharides (XOS). AEs were similarly restricted in their action and apparently removed in most cases only one acetyl group from the non-reducing end of XOS, acting as exo-deacetylases. In contrast, AXEs completely deacetylated longer neutral XOS but had difficulties with the shorter ones. Complete deacetylation of neutral XOS was obtained after the combined action of AEs and AXEs. MeGlcA substituents partially restricted the action of both types of esterases and the remaining acidic XOS were mainly substituted with one MeGlcA and one acetyl group, supposedly on the same xylopyranosyl residue. These resisting structures were degraded to great extent only after inclusion of α-glucuronidase, which acted with the esterases in a synergistic manner. When used together with xylan backbone degrading endoxylanase and β-xylosidase, both AE and AXE enhanced the hydrolysis of complex XOS equally. 相似文献
1000.
Rodrigo Caccere Simone P. Teixeira Danilo C. Centeno Rita de Cássia L. Figueiredo-Ribeiro Márcia R. Braga 《Journal of plant physiology》2013
Inga vera, native to South America, is an important leguminous species used for ecological restoration of riparian forests and its seeds are among the most recalcitrant ones described up to date. In this work, we analysed the metabolic profile, cell ultrastructure as well as cell wall polysaccharides of I. vera seeds in order to better understand its maturation, which allows embryo germination without a quiescent phase. Increased amounts of citric, glutamic, pyroglutamic, and aspartic acids from stages I to II (120 and 129 days after flowering (DAF)) corroborate the hypothesis of high metabolism, shifting from fermentative to aerobic respiration at seed maturity. This phase was characterized by an extensive vacuolization of embryonic cells, which also indicate high metabolic activity. The proportion of arabinose in the cell walls of embryonic axis (approx. 20%) was lower than those found in some orthodox seeds (nearly 40%), suggesting that arabinose-containing polysaccharides, which are thought to provide more flexibility to the cell wall during natural drying, are less abundant in I. vera seeds. Taken together, our results provide evidence that the major changes occurred during early stages of seed maturation of I. vera, indicating that the rapid temporary metabolic shift observed between stages I and II may be related to the lack of desiccation phase, moving directly to germination. 相似文献