首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   330篇
  免费   17篇
  2024年   1篇
  2023年   3篇
  2022年   6篇
  2021年   8篇
  2020年   7篇
  2019年   3篇
  2018年   11篇
  2017年   6篇
  2016年   9篇
  2015年   29篇
  2014年   24篇
  2013年   22篇
  2012年   34篇
  2011年   31篇
  2010年   23篇
  2009年   11篇
  2008年   14篇
  2007年   22篇
  2006年   21篇
  2005年   12篇
  2004年   6篇
  2003年   7篇
  2002年   9篇
  2001年   2篇
  2000年   5篇
  1999年   3篇
  1998年   1篇
  1997年   2篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1988年   1篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1934年   1篇
排序方式: 共有347条查询结果,搜索用时 328 毫秒
101.
Data indicated that dyslexic individuals exhibited difficulties on tasks involving Working Memory (WM). Previous studies have suggested that these deficits stem from impaired processing in the Phonological Loop (PL). The PL impairment was connected to poor phonological processing. However, recent data has pointed to the Central Executive (CE) system as another source of WM deficit in dyslexic readers. This opened a debate whether the WM deficit stems solely from PL or can also be seen as an outcome of poor CE processing. In an attempt to verify this question, the current study compared adult skilled and compensated dyslexic readers with no impairment of phonological skills. The participants’ PL and CE processing were tested by using the fNIR device attached to the frontal lobe and measured the changes in brain oxygen values when performing N-back task. As it was previously suggested, the N = 0 represented PL and N = 1 to 3 represent CE processing. It was hypothesized that dyslexic readers who show non-impaired phonological skills will exhibit deficits mainly in the CE subsystem and to a lesser extent in the PL. Results indicated that the two reading level groups did not differ in their accuracy and reaction times in any of the N-Back conditions. However, the dyslexic readers demonstrated significant lower maximum oxyHb values in the upper left frontal lobe, mainly caused due to a significant lower activity under the N = 1 condition. Significant task effects were found in the medial left hemisphere, and the high medial right hemisphere. In addition, significant correlations between fNIR-features, reading performance and speed of processing were found. The higher oxyHb values, the better reading and speed of processing performance obtained. The results of the current study support the hypothesis that at least for the group of dyslexics with non-impaired PL, WM deficit stems from poor CE activity.  相似文献   
102.
The bursa of Fabricius is critical for B cell development and differentiation in chick embryos. This study describes the production in vitro, from dissociated cell suspensions, of cellular agglomerates with functional similarities to the chicken bursa. Co-cultivation of epithelial and lymphoid cells obtained from embryos at the appropriate developmental stage regularly led to agglomerate formation within 48 hours. These agglomerates resembled bursal tissue in having lymphoid clusters overlaid by well organized epithelium. Whereas lymphocytes within agglomerates were predominantly Bu-1a+, a majority of those emigrating onto the supporting membrane were Bu-1a and IgM+. Both agglomerates and emigrant cells expressed activation-induced deaminase with levels increasing after 24 hours. Emigrating cells were actively proliferating at a rate in excess of both the starting cell population and the population of cells remaining in agglomerates. The potential usefulness of this system for investigating the response of bursal tissue to avian Newcastle disease virus (strain AF2240) was examined.  相似文献   
103.
The present investigation reports the sequence of a 2.97KDa low molecular weight, cationic antibacterial peptide, caP4 isolated from wild variety of turmer  相似文献   
104.
In the present study, a laboratory scale anoxic/oxic (A/O) reactor is used for the removal of nutrient and sludge reduction. Phosphorus removal was achieved through simultaneous precipitation, and sludge production was reduced through thermochemical pretreatment. The main objective of the study was to investigate the influence of sludge pretreatment on the nitrification rate. Total phosphorus in the effluent was maintained around 0.5 ~ 1.0 mg/L by simultaneous precipitation, using coagulant alum at 2.2 mole ratio. Before simultaneous precipitation, the nitrification rate of the A/O reactor was found to be 0.050 g N-NH4 +/g MLVSS.d. The thermochemical sludge pretreatment began on the 120th day at pH 11 and 80°C. The initiation of sludge pretreatment brought about a significant reduction of the A/O reactor nitrification rate, which fell to 0.038 g N-NH4 +/g MLVSS/day. The effect of sludge pretreatment was reflected in the reduction of the nitrogen removal efficiency from 85 to 74%. Recycling of the thermochemically pretreated sludge accounted for 57% sludge reduction, which had an adverse influence on the nitrification rate of the system.  相似文献   
105.
106.
A strain isolated from waste of a milk products plant and exhibited extracellular lipolytic activity was identified as Debaryomyces hansenii by 5.8S rRNA and 28S rRNA gene sequence analyses. Lipolytic activity was assayed spectrophotometrically by using p-nitrophenylpalmitate. Higher specific lipolytic activities were obtained in the presence of tristearin (0.68 U/mg prot), oleic acid (0.56 U/mg prot), and soybean oil (0.36 U/mg prot) than other triglycerides, fatty acids, and vegetable oils considered as carbon sources. Cheese whey appeared to be a good alternative to lipidic substances for lipolytic activity. Among various organic and inorganic nitrogen sources, soy flour was found to attain the lipolytic activity similar to that provided by universal yeast medium components. This work is the first report on the discussion of lipolytic activity enhancement by D. hansenii through modulating the cultivation medium. It also proposes low cost medium nutrients that could be of industrial value and could serve as basal nutrients for further optimization studies on the lipase production by D. hansenii.  相似文献   
107.
Chifiriuc MC  Banu O  Bleotu C  Lazar V 《Anaerobe》2011,17(6):419-421

Purpose

To identify the relationships between some infectious agents implicated in cardiovascular diseases with the cellular substrate and prosthetic devices in the presence of antibiotics.

Specific objectives

Strains isolation and identification, comparative study of antibiotic resistance of planktonic (disk diffusion, E-test, automatic systems) and sessile (using original experimental models for in vitro development of monospecific biofilms) bacterial cells, virulence assays (adherence and invasion of HeLa cells, slime test, soluble virulence factors expression), dynamic study of biofilm development on inert substrata, under the influence of antibiotics, the influence of cellular and soluble bacterial fractions on HeLa cells (by flow cytometry and real-time PCR).

Results

The identified strains were isolated from different sources, the etiology being dominated by Gram-negative non-fermentative bacilli, Gram-positive cocci and yeasts, harboring invasion enzymes responsible for development of systemic infections. The isolated strains exhibited a high level of antibiotic resistance to beta-lactams, aminoglycosides and quinolones, and an evident tendency of colonizing the cellular and inert substrate, the degree of colonization depending on the physico-chemical nature of the substrate. By comparison with planktonic ones, the sessile bacterial strains expressed a changed profile of antibiotic resistance, this aspect being very important for the readjustment of the treatment and prevention of infections associated with prosthetic devices. In vitro experiments suggested that different fractions of S. aureus cultures could trigger the release of proinflammatory (TNF-α, IL-1b, IL-6) and anti-inflammatory (IL-8) cytokines and induced apoptosis in HeLa cells.  相似文献   
108.
Abstract

In contrast to the huge amount of research on Turkish migration and migrants, the diasporic politics of the Turkish Kemalist state constitutes a neglected research subject in the scholarship on Turkish diaspora. How does the Turkish state reach out to its nationals and expatriates abroad? In what ways does the Turkish Republic seek to make Islam (as it does in Turkey) into an instrument legitimizing its politicizing and mobilizing enterprises? To explore these questions, this article investigates the long-distance Kemalism engaged in by the Turkish state to Turkify and secularize its nationals in the diaspora, using its activities in Australia as its case study. In sketching out trans-Kemalism's dimensions, the analysis directs attention to the intimate relationship between the political and religious fields of transnationalism manufactured by the state. The paper concludes that the intense political polarization in Turkey in the present makes the future of trans-Kemalism abroad somewhat uncertain.  相似文献   
109.
Biofilms of selected bacteria strains were previously used on metal coupons as a protective layer against microbiologically influenced corrosion of metals. Unlike metal surfaces, concrete surfaces present a hostile environment for growing a protective biofilm. The main objective of this research was to investigate whether a beneficial biofilm can be successfully grown on mortar surfaces. Escherichia coli DH5α biofilm was grown on mortar surfaces for 8 days, and the structure and characteristics of the biofilm were studied using advanced microscopy techniques such as scanning electron microscopy and confocal laser scanning microscopy in combination with fluorescence in situ hybridization, live/dead, extracellular polymer staining, ATP analysis, and membrane filtration. A biofilm layer with a varying thickness of 20–40 μm was observed on the mortar surface. The distribution of live and dead bacteria and extracellular polymers varied with depth. The density of the live population near the mortar surface was the lowest. The bacteria reached their highest density at three fourths of the biofilm depth and then decreased again near the biofilm–liquid interface. Overall, the results indicated a healthy biofilm growth in the chosen growth period of 8 days, and it is expected that longer growth periods would lead to formation of a more resistant biofilm with more coverage of mortar surfaces.  相似文献   
110.

Objective:

In murine models of obesity/diabetes, there is an increase in plasma serum amyloid A (SAA) levels along with redistribution of SAA from high‐density lipoprotein (HDL) to apolipoprotein B (apoB)‐containing lipoprotein particles, namely, low‐density lipoprotein and very low‐density lipoprotein. The goal of this study was to determine if obesity is associated with similar SAA lipoprotein redistribution in humans.

Design and Methods:

Three groups of obese individuals were recruited from a weight loss clinic: healthy obese (n = 14), metabolic syndrome (MetS) obese (n = 8), and obese with type 2 diabetes (n = 6). Plasma was separated into lipoprotein fractions by fast protein liquid chromatography, and SAA was measured in lipid fractions using enzyme‐linked immunosorbent assay and Western blotting.

Results:

Only the obese diabetic group had SAA detectable in apoB‐containing lipoproteins, and SAA reverted back to HDL with active weight loss.

Conclusions:

In human subjects, SAA is found in apoB‐containing lipoprotein particles only in obese subjects with type 2 diabetes, but not in healthy obese or obese subjects with MetS.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号