全文获取类型
收费全文 | 323篇 |
免费 | 27篇 |
国内免费 | 17篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 19篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 16篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 20篇 |
2006年 | 17篇 |
2005年 | 24篇 |
2004年 | 14篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有367条查询结果,搜索用时 15 毫秒
41.
Boon-Seng Wong David R. Brown † Tao Pan Matthew Whiteman ‡ Tong Liu Xiaodong Bu § Ruliang Li Pierluigi Gambetti John Olesik § Richard Rubenstein¶ Man-Sun Sy 《Journal of neurochemistry》2001,79(3):689-698
Prion diseases are characterized by the conversion of the normal cellular prion protein (PrP(C)) into a pathogenic isoform (PrP(Sc)). PrP(C) binds copper, has superoxide dismutase (SOD)-like activity in vitro, and its expression aids in the cellular response to oxidative stress. However, the interplay between PrPs (PrP(C), PrP(Sc) and possibly other abnormal species), copper, anti-oxidation activity and pathogenesis of prion diseases remain unclear. In this study, we reported dramatic depression of SOD-like activity by the affinity-purified PrPs from scrapie-infected brains, and together with significant reduction of Cu/Zn-SOD activity, correlates with significant perturbations in the divalent metals contents. We also detected elevated levels of nitric oxide and superoxide in the infected brains, which could be escalating the oxidative modification of cellular proteins, reducing gluathione peroxidase activity and increasing the levels of lipid peroxidation markers. Taken together, our results suggest that brain metal imbalances, especially copper, in scrapie infection is likely to affect the anti-oxidation functions of PrP and SODs, which, together with other cellular dysfunctions, predispose the brains to oxidative impairment and eventual degeneration. To our knowledge, this is the first study documenting a physiological connection between brain metals imbalances, the anti-oxidation function of PrP, and aberrations in the cellular responses to oxidative stress, in scrapie infection. 相似文献
42.
Nugent Greg Chandler Stephen F. Whiteman Phil Stevenson Trevor W. 《Plant Cell, Tissue and Organ Culture》2001,67(1):85-88
Somatic embryos were obtained from 1% of cotyledon pieces and hypocotyls of mature embryos of Eucalyptus globulus Labill. cultured on media containing a high concentration of picloram or IBA. 2,4-D and other synthetic auxins did not yield somatic embryos or embryogenic callus. Somatic embryos arose indirectly via callus, being visible after four months, and directly, where little callus or adventitious root initiation occurred. Somatic embryos, formed directly from explants, were visible within five weeks. Various structural abnormalities of somatic embryos were observed, especially after induction on media containing picloram. Only two out of fifteen somatic embryos showed hypocotyl and radical elongation, but plantlets did not develop further. 相似文献
43.
44.
Paul D. Nabity Greg A. Barron-Gafford Noah K. Whiteman 《Current biology : CB》2021,31(6):1344-1350.e3
- Download : Download high-res image (260KB)
- Download : Download full-size image
45.
46.
Yi Zhun Zhu Zhong Jing Wang Peiying Ho Yoke Yun Loke Yi Chun Zhu Shan Hong Huang Chee Sin Tan Matt Whiteman Jia Lu Philip K Moore 《Journal of applied physiology》2007,102(1):261-268
The role of hydrogen sulfide (H(2)S) in myocardial infarction (MI) has not been previously studied. We therefore investigated the effect of H(2)S in a rat model of MI in vivo. Animals were randomly divided into three groups (n = 80) and received either vehicle, 14 micromol/kg of sodium hydrosulfide (NaHS), or 50 mg/kg propargylglycine (PAG) everyday for 1 wk before surgery, and the treatment was continued for a further 2 days after MI when the animals were killed. The mortality was 35% in vehicle-treated, 40% in PAG-treated, and 27.5% in NaHS-treated (P < 0.05 vs. vehicle) groups. Infarct size was 52.9 +/- 3.5% in vehicle-treated, 62.9 +/- 7.6% in PAG-treated, and 43.4 +/- 2.8% in NaHS-treated (P < 0.05 vs. vehicle) groups. Plasma H(2)S concentration was significantly increased after MI (59.2 +/- 7.16 microM) compared with the baseline concentration (i.e., 38.2 +/- 2.07 microM before MI; P < 0.05). Elevated plasma H(2)S after MI was abolished by treatment of animals with PAG (39.2 +/- 5.02 microM). We further showed for the first time cystathionine-gamma-lyase protein localization in the myocardium of the infarct area by using immunohistochemical staining. In the hypoxic vascular smooth muscle cells, we found that cell death was increased under the stimuli of hypoxia but that the increased cell death was attenuated by the pretreatment of NaHS (71 +/- 1.2% cell viability in hypoxic vehicle vs. 95 +/- 2.3% in nonhypoxic control; P < 0.05). In conclusion, endogenous H(2)S was cardioprotective in the rat model of MI. PAG reduced endogenous H(2)S production after MI by inhibiting cystathionine-gamma-lyase. The results suggest that H(2)S might provide a novel approach to the treatment of MI. 相似文献
47.
The initial steps in taste and olfaction result from the activation by
chemical stimuli of taste receptor cells (TRCs) and olfactory receptor
neurons (ORNs). In parallel with these two pathways is the chemosensitive
trigeminal pathway whose neurons terminate in the oral and nasal cavities
and which are activated by many of the same chemical stimuli that activate
TRCs and ORNs. In a recent single unit study we investigated the responses
of rat chorda tympani and glossopharnygeal neurons to a variety of
bitter-tasting alkaloids, including nicotine, yohimbine, quinine,
strychnine and caffeine, as well as capsaicin, the pungent ingredient in
hot pepper. Here we apply many of these same compounds to cultured rat
trigeminal ganglion (TG) neurons and measure changes in intracellular
calcium [Ca2+]i to determine whether TG neurons will respond to these same
compounds. Of the 89 neurons tested, 34% responded to 1 mM nicotine, 7% to
1 mM caffeine, 5% to 1 mM denatonium benzoate, 22% to 1 mM quinine
hydrochloride, 18% to 1 mM strychnine and 55% to 1 microM capsaicin. These
data suggest that neurons from the TG respond to the same bitter-tasting
chemical stimuli as do TRCs and are likely to contribute information sent
to the higher CNS regarding the perception of bitter/irritating chemical
stimuli.
相似文献
48.
The estimation of acid glycosaminoglycan-Alcian blue complexes eluted from electrophoretic strips 总被引:4,自引:0,他引:4
The present report describes a new and simple method for the detection and quantitative determination of pentoses and hexuronic acids either separately or in a mixture. The method involves treatment of the sample with sulfuric acid followed by the addition of harmine and then cysteine. Hexuronic acids produce a pink color with harmine, while pentoses react only after the addition of cysteine. Hexosamines, methylpentoses, and moderate amounts of hexoses do not interfere with these determinations.The method is simple, accurate, and allows the determination of small amounts of pentoses in the presence of larger amounts of hexuronic acids and other sugars. 相似文献
49.
Paul Whiteman 《The Biochemical journal》1973,131(2):343-350
1. A simple new quantitative micro method was developed to study the interaction of the cationic dye Alcian Blue 8GX and acid glycosaminoglycans under different conditions. After washing with ethanol the precipitated Alcian Blue-glycosaminoglycan complex was dissociated in Manoxol IB solution and the amount of bound dye measured spectrophotometrically. 2. Reaction profiles of complex-formation were determined in the presence of different concentrations of MgCl(2) at pH5.8, and could be used to study the critical electrolyte concentrations of glycosaminoglycans. At least 50mm-MgCl(2) was required to produce maximum precipitation of, and maximum uptake of, Alcian Blue by standard glycosaminoglycans. Maximum uptake of Alcian Blue by glycosaminoglycans in the urine of a patient with Hurler's syndrome required the presence of 25-50mm-MgCl(2). 3. Under standard conditions of maximum interaction, calibration curves for the quantitative determination of a series of standard glycosaminoglycans in 20mul volumes were nearly linear over the range 1-10mug. 4. The technique was used to determine the molecular binding ratios of Alcian Blue to glycosaminoglycans under controlled conditions. 相似文献
50.
Paul Whiteman 《The Biochemical journal》1973,131(2):351-357
1. The effect of MgCl(2) concentration on the interaction of Alcian Blue 8GX and glycosaminoglycans in the urine of patients with mucopolysaccharidosis was studied by using a new quantitative micro method for the measurement of Alcian Blue-glycosaminoglycan complexes. This provided a means of measuring the critical electrolyte concentrations of urinary glycosaminoglycans. 2. Theoretical considerations based on the preceding paper (Whiteman, 1973) and experimental evidence provided here show that Alcian Blue 8GX may be used for the direct quantitative determination of total urinary glycosaminoglycans. The method is simple, requires sample volumes of 50mul or less, and gives results comparable with those obtained by other more complicated methods. 相似文献