全文获取类型
收费全文 | 806篇 |
免费 | 50篇 |
国内免费 | 1篇 |
专业分类
857篇 |
出版年
2023年 | 4篇 |
2022年 | 17篇 |
2021年 | 27篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 30篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 47篇 |
2014年 | 56篇 |
2013年 | 64篇 |
2012年 | 85篇 |
2011年 | 86篇 |
2010年 | 44篇 |
2009年 | 37篇 |
2008年 | 62篇 |
2007年 | 45篇 |
2006年 | 34篇 |
2005年 | 28篇 |
2004年 | 28篇 |
2003年 | 13篇 |
2002年 | 24篇 |
2001年 | 12篇 |
2000年 | 13篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 4篇 |
1988年 | 2篇 |
排序方式: 共有857条查询结果,搜索用时 0 毫秒
11.
Purpose
To investigate light transmission and preference for six eye patches for occlusion therapy.Methods
Six patches were examined, including; Ortopad Fun Pack, Ortopad Flesh, Kawamoto A-1, Kawamoto A-2, 3M Opticlude, and Everade Eye Guard. The size and the presence of a light blocking pad of patches were investigated. The amount of light transmitted through the patches was evaluated, using a digital light meter and a model eye, in three different environments; indoors with fluorescent light, outdoors on a sunny day, and strong light from illuminator. After patching the normal eye, the flash visual evoked potential (VEP) was measured. Thirty patients with amblyopia or horizontal strabismus, who received occlusion therapy as initial treatment, were included. After using all six patches, patients completed a 7-item questionnaire regarding the patch preference for size, color and shape, adhesive power, pain with removal, skin irritation after removing patch, parent’s preference and overall opinion.Results
All patches had a light-blocking pad, except the 3M Nexcare. Ortopad had the strongest light blocking power in the three environments, and the 3M Nexcare had the weakest power. In flash VEP, Ortopad and Kawamoto patches showed flat, but 3M Nexcare and Everade Eye Guard showed normal response. There were significant preferential differences among the patches in all the items of the questionnaire (P<0.05). In comparison between the patches respectively, 3M Nexcare received the lowest satisfaction in pain when removing a patch and skin irritation after removing a patch. Kawamoto A-2 received the lowest score in the overall satisfaction.Conclusions
We found differences in the light-blocking power and in the preference of the various patches for the occlusion treatment. This is a pilot study regarding only characteristics and preferences of patches. Further clinical studies regarding the relationship between characteristics or preferences of patches and outcomes of occlusion treatment are needed. 相似文献12.
13.
14.
A new sensitive and selective detection of Ga3+ by thiophene-based ‘turn-on’ fluorescent chemosensor
We designed a thiophene-based fluorescent chemosensor DHTC ((E)-2-([3,5-dichloro-2-hydroxybenzylidene]amino)thiophene-3-carboxamide) for detecting gallium (Ga3+). DHTC could probe Ga3+ using fluorescence enhancement. The limit of detection for Ga3+ by DHTC was 0.39 μM. The binding mode of DHTC to Ga3+ was determined as a 1:1 ratio from analysis by Job’s plot and electrospray ionization-mass spectrometry (ESI-MS). In addition, DHTC could selectively detect Ga3+ using test kits. The sensing process of Ga3+ by DHTC was presented using ultraviolet–visible light titration, Job’s plot, ESI-MS, 1H nuclear magnetic resonance titration, and density functional theory calculation. 相似文献
15.
Induction of Betalain Pigmentation in Hairy Roots of Red Beet under Different Radiation Sources 总被引:5,自引:0,他引:5
The effects of aluminum on lipid peroxidation and activities of antioxidative enzymes were investigated in detached rice leaves treated with 0 to 5 mM AlCl3 at pH 4.0 in the light. AlCl3 enhanced the content of malondialdehyde but not the content of H2O2. Superoxide dismutase activity was reduced by AlCl3, while catalase and glutathione reductase activities were increased. Peroxidase and ascorbate peroxidase activities were increased only after prolonged treatment, when toxicity occurred. The results give evidence that Al treatment caused oxidative stress and in turn, it caused lipid peroxidation. 相似文献
16.
S.-J. Heo K. Tatebayashi J. Kato H. Ikeda 《Molecular genetics and genomics : MGG》1998,257(2):149-156
The Saccharomyces cerevisiae gene RHC21 is a homologue of the fission yeast rad21 +gene, which affects the sensitivity of cells to γ-irradiation and is essential for cell growth in S. pombe. Disruption of the RHC21 gene showed that it is also essential in S. cerevisiae. To examine its function in cell growth further, we have isolated temperature-sensitive mutants for the RHC21 gene and characterized one of them, termed rhc21-sk16. When this mutant was incubated at 36°?C, the percentage of large-budded cells was increased. Most of the large-budded cells had aberrant nuclear structures, such as unequally extended nuclear DNA with incompletely elongated spindles across the mother-daughter neck or only in a mother cell. Furthermore, a circular minichromosome is more unstable in the mutant than in the wild-type, even at 25°?C. Flow cytometry showed that the bulk of DNA replication takes place normally at the restrictive temperature in the mutant. These results indicated that the RHC21 gene is required for proper segregation of the chromosomes. In addition, we found that the mutant is sensitive not only to UV radiation and γ-rays but also to the antimicrotubule agent nocodazole at 25°?C. This suggests that the RHC21 gene is involved in the microtubule function. We discuss how the RHC21 gene product may be involved in chromosome segregation and microtubule function. 相似文献
17.
The hybrid cluster protein (HCP; formerly termed the prismane protein) has been extensively studied due to its unique spectroscopic properties. Although the structural and spectroscopic characteristics are well defined, its enzymatic function, up to this point, has remained unidentified. While it was proposed that HCP acts in some step of nitrogen metabolism, a specific role for this enzyme remained unknown. Recent studies of HCP purified from Escherichia coli have identified a novel hydroxylamine reductase activity. These data reveal the ability of HCP to reduce hydroxylamine in vitro to form NH(3) and H(2)O. Further biochemical analyses were completed in order to determine the effects of various electron donors, different pH levels, and the presence of CN(-) on in vitro hydroxylamine reduction. 相似文献
18.
Myles S Faith Kathleen L Keller Patty Matz Susan L Johnson Rebecca Lewis Marie Alexandra Jorge Clare Ridley Helen Han Shoshanna Must Moonseong Heo Angelo Pietrobelli Steven B Heymsfield David B Allison 《Twin research》2002,5(5):472-475
"Project Grow-2-Gether" is a child nutrition study of same-sex, 3- to 7-year-old monozygotic and dizygotic twin pairs. The study attempts to bridge two bodies of literature that have rarely interfaced with respect to obesity and ingestive behavior: the first being behavioral genetic approaches to obesity-related traits, and the second being developmental approaches focusing on parent-child relationships. The overarching aim of Project Grow-2-Gether is to disentangle genetic from potential home-environmental influences on child eating behavior and body fat. This paper reviews the rationale for Project Grow-2-Gether, its procedures, and core phenotypic measurement battery. A focus of the study is acquisition of controlled food intake measurements obtained in the laboratory, measurement of specific home environmental variables, and multi-method evaluation of parent-child feeding relations. Future directions may involve longitudinal assessment of child growth and molecular analyses for specific genes that influence child eating behavior. 相似文献
19.
Heo HJ Cho HY Hong B Kim HK Heo TR Kim EK Kim SK Kim CJ Shin DH 《Molecules and cells》2002,13(1):5-11
Amyloid beta protein (Abeta) increases free radical production and lipid peroxidation in PC12 nerve cells, leading to apoptosis and cell death. The effect of ursolic acid from Origanum majorana L. on Abeta-induced neurotoxicity was investigated using PC12 cells. Pretreatment with isolated ursolic acid and vitamin E prevented the PC12 cell from reactive oxygen species (ROS) toxicity that is mediated by Abeta. The ursolic acid resulted in decreased Abeta toxicity assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and trypan blue assay. Thus, treatment with these antioxidants inhibited the Abeta-induced neurotoxic effect. Therefore, these results indicate that micromolar Abeta-induced oxidative cell death is reduced by ursolic acid from Origanum majorana L. 相似文献
20.
To maintain embryogenic cell lines ofPimpinella brachycarpa, we suspension-cultured friable and rapidly growing yellowish calli in an MS liquid medium containing 0.2 ~ 2,4-D and 0.5pM BAP. Efficient somatic embryogenesis was achieved when selected cells were then transferred to an MS medium (0.2% gelrite)
that contained 0.2gM 2,4-D, 0.5 uM BAP, and 10.0 laM TDZ (thidiazuron). These cells were cultured at 27°C under continuous illumination (21.5
I~E m-2 s-l). Embryogenic calli expanded about four-fold, and developed into pale yellow calli. Somatic embryogenesis was initiated only
from glossy and nodular-type calli. After two more weeks of culture, globular embryos appeared on the surface of calli grown
in the MS medium that contained 10.0 /aM TDZ only, or in combination with 0.5 gM NAA. Experimenting with 2,4-D, an auxin,
to promote embryogenic calli resulted in excessive browning and death. We overcame this problem by growing glossy embryogenic
and nodular calli on media that contained 10.0 gM TDZ. Calli that were not treated with TDZ turned dark brown and were not
viable. Up to 74% of the calli showed somatic embryos when the medium was supplemented with 10.0 uM TDZ and 0.5 uM NAA. Embryos
from these TDZ-induced, somatic embryogenic calli grew efficiently, forming multiple shoots and developing into normal plants.
Therefore, efficient differentiation of suspension-cultured cell clusters into embryogenic calli, along with treatment of
subsequent somatic embryos by TDZ, suggests that TDZ probably helps in establishing the optimum cytokinin-auxin ratio required
for induction and expression of somatic embryogenesis. 相似文献