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   109篇
  免费   11篇
  120篇
  2023年   1篇
  2021年   1篇
  2020年   3篇
  2019年   3篇
  2017年   2篇
  2016年   6篇
  2015年   7篇
  2014年   3篇
  2013年   9篇
  2012年   10篇
  2011年   2篇
  2010年   5篇
  2009年   3篇
  2008年   10篇
  2007年   7篇
  2006年   5篇
  2005年   3篇
  2004年   6篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  1999年   2篇
  1998年   4篇
  1997年   1篇
  1996年   4篇
  1995年   1篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1982年   2篇
  1978年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有120条查询结果,搜索用时 0 毫秒
11.
12.
The aim of this study was to examine the effect of adrenal versus ovarian androgen (dehydroepiandrosterone sulfate/total testosterone [DHEAS/TT]) on clinical presentation and related metabolic disturbances in Turkish women with polycystic ovarian syndrome (PCOS). Two hundred eighty PCOS cases were taken into the study. For all cases, the DHEAS/TT ratio was calculated. The median value of this ratio was 4.40. Patients with an androgen ratio lower than 4.40 were included in Group 1 and cases with a ratio higher than 4.40 were Group 2. The two groups were compared in terms of hormonal, biochemical and clinical parameters. Body mass index and waist circumference were lower, the Ferriman-Gallwey score was higher and the cycle length was shorter in Group 2. High DHEAS level was associated with better lipid profiles and lower levels of inflammatory markers, meaning good metabolic control in these women, in spite of increased hirsutism rates. In patients with PCOS, both androgens are usually high in proportion to each other. Therefore, it would be more meaningful to use the DHEAS/TT ratio for an assessment of the metabolic and phenotypic effects of PCOS.  相似文献   
13.
Impaired glucose tolerance: its relevance to early endothelial dysfunction.   总被引:2,自引:0,他引:2  
We studied the effects of acute glycemia on plasma nitric oxide (NO; nitrite plus nitrate) levels, Cu-Zn Superoxide dismutase (Cu-Zn SOD) activity and thiobarbituric acid-reactive substances (TBARS) levels in age-matched female subjects before and two hours after glucose loading. According to the results of glucose loading, subjects were divided in the three groups as normal (n = 13, NGT), impaired (n = 11, IGT) and diabetic glucose tolerance (n = 10, DGT). Plasma NO levels were significantly higher in subjects with DGT than in subjects with NGT (p< 0.001) and IGT (p< 0.05) at baseline. Two hours after glucose loading, plasma NO levels were significantly decreased in subjects with IGT and DGT (p< 0.001 and p< 0.001). Although plasma TBARS levels in subject with NGT did not change from the baseline levels after glucose loading, TBARS levels were significantly elevated in subjects with DGT and IGT (p< 0.001 and p< 0.001). Plasma Cu-Zn SOD activities were within a similar range in all subjects at baseline. Cu-Zn SOD activities were significantly increased in subjects with NGT, and were significantly decreased in subjects with IGT and DGT (p< 0.001 and p< 0.001) after glucose loading. There was a positive correlation between NO and glucose in subjects with NGT (r = 0.34, p< 0.01) and a negative correlation between NO and TBARS in IGT sum DGT during glucose tolerance (r= -0.38, p< 0.01). We suggest that NO availability was decreased when the blood glucose levels were only moderately elevated above normal levels. This might be related with the enhanced oxidative stress.  相似文献   
14.
Pot experiments were designed to evaluate the efficacy of Streptomyces nobilis, S. ochraceiscleroticus, Neocosmospora vasmfecta var. Africana and Acrophialophora levis isolates in reducing the damping-off on pepper in comparison with a strong mycoparasitic isolate of Trichoderma harzianum. Two pathogenic and five potential antagonistic isolates were grown seperately m flasks containing a mixture of sand-perlite-corn meal and potato-sucrose broth for 4 weeks. Soil infestation was achieved by mixing these stock cultures separately into the pot soils. Disease incidence was expressed as the percentages of dead seedlings in each pot and the protective values of the antagonists were calculated according to Abbott formula. Results indicated that all of the five test isolates have provided the seedhngs with protection of statistical value against Pythium uhimum and Rhizocionia solani reducing disease incidence between 28.14 to 79.14 % and 22.76 to 66.83 %, respectively. However, T. harzianum isolate proved to be the least effective antagonist against both pathogens.  相似文献   
15.
16.
A central feature of intussusceptive angiogenesis is the development of an intravascular pillar that bridges the opposing sides of the microvessel lumen. In this report, we created polydimethyl siloxane (PDMS) microchannels with geometric proportions based on corrosion casts of the colon microcirculation. The structure of the PDMS microchannels was a bifurcated channel with an intraluminal pillar in the geometric center of the bifurcation. The effect of the intraluminal pillar on particle flow paths was investigated using an in vitro perfusion system. The microchannels were perfused with fluorescent particles, and the particle movements were recorded using fluorescence videomicroscopy. We found that the presence of an intravascular pillar significantly decreased particle velocity in the bifurcation system (p < 0.05). In addition, the pillar altered the trajectory of particles in the center line of the flow stream. The particle trajectory resulted in prolonged pillar contact as well as increased residence time within the bifurcation system (p < 0.001). Our results suggest that the intravascular pillar not only provides a mechanism of increasing resistance to blood flow but may also participate in spatial redistribution of cells within the flow stream. Supported in part by NIH Grants HL47078, HL75426, HL054885, HL070542 and HLO74022.  相似文献   
17.
Fourteen elite sorghum lines were evaluated for their resistance to Striga hermonthica at three locations in Nigeria and Mali. Results showed that many of the lines especially MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64 (Keninkédié) and the check SRN 39 remained resistant to Striga in all locations with low emerged Striga counts, while SAMSORG 14 had the highest Striga infestation in all locations. Considerable variation in reaction to Striga infestation was observed on Séguètana, 97-SB-F5DT-63 (Wasa), 97-SB-F5DT-65, CMDT 38, CMDT 39 and CMDT 45 which were susceptible to Striga at Samaru, Nigeria but were resistant to Striga at both locations in Mali. Based on low Striga resistance and high grain yield, lines MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64, 97-SB-F5DT-65, CMDT 39 and SAMSORT 14 have been nominated for wider evaluation across more West African countries.  相似文献   
18.
The purposes of this study were to determine the separate and interactive functions of progesterone and estradiol in regulating the cervical prostaglandin (PG) system in pregnant sheep at 0.7 gestations. At 106-108 days of gestational age (dGA), ewes were treated with vehicle for 14 days (n = 5) or vehicle for 12 days followed by estradiol 5 mg twice a day, intramuscularly for 2 days (n = 5) or progesterone 100 mg, twice a day, intramuscularly for 14 days (n = 5) or progesterone 100 mg twice a day, intramuscularly for 10 days and then 2 days vehicle followed by estradiol 5 mg twice a day intramuscularly for 2 days (n = 5). At 121-123 dGA, cervical tissues were obtained under halothane anesthesia. Cervical RNA and protein were extracted and analyzed for prostaglandin-endoperoxide synthase 2 (COX2), two PGE(2) receptors, PTGER2 and PTGER4, and estrogen receptor alpha (ESR1) by Northern and Western blot analysis. Immunocytochemistry and in situ hybridization were applied to localize cellular distribution of COX2, PTGER2, and PTGER4 in the cervix. Data were analyzed by ANOVA. COX2 and PTGER4 mRNAs and proteins were increased (P < 0.05) in ewes treated with combined estradiol and progesterone but not in ewes treated with estradiol or progesterone alone compared with controls. ESR1 mRNA was increased in ewes treated with progesterone and estradiol plus progesterone. In contrast, PTGER2 mRNA and protein remained the same after all treatments. COX2 mRNA and protein were localized only in cervical glandular epithelial cells, whereas PTGER2 and PTGER4 were localized in both cervical glandular epithelial and smooth muscle cells. In conclusion, these data suggest that additional progesterone priming at 0.7 gestations synergizes with estradiol to induce cervical COX2, PTGER4, and ESR1 and support our hypothesis that stimulation of the cervical PG system by estradiol is optimized by sufficient progesterone priming in the pregnant sheep cervix.  相似文献   
19.
The goal of this study was to produce ethanol from rice hull hydrolysates (RHHs) using Pichia stipitis strains and to optimize dilute acid hydrolysis and detoxification processes by response surface methodology (RSM). The optimized conditions were found as 127.14°C, solid:liquid ratio of 1:10.44 (w/v), acid ratio of 2.52% (w/v), and hydrolysis time of 22.01 min. At these conditions, the fermentable sugar concentration was 21.87 g/L. Additionally, the nondetoxified RHH at optimized conditions contained 865.2 mg/L phenolics, 24.06 g/L fermentable sugar, no hydroxymethylfurfural (HMF), 1.62 g/L acetate, 0.36 g/L lactate, 1.89 g/L glucose, and 13.49 g/L fructose + xylose. Furthermore, RHH was detoxified with various methods and the best procedures were found to be neutralization with CaO or charcoal treatment in terms of the reduction of inhibitory compounds as compared to nondetoxified RHH. After detoxification procedures, the content of hydrolysates consisted of 557.2 and 203.1 mg/L phenolics, 19.7 and 21.60 g/L fermentable sugar, no HMF, 0.98 and 1.39 g/L acetate, 0 and 0.04 g/L lactate, 1.13 and 1.03 g/L glucose, and 8.46 and 12.09 g/L fructose + xylose, respectively. Moreover, the base‐line mediums (control), and nondetoxified and detoxified hydrolysates were used to produce ethanol by using P. stipitis strains. The highest yields except that of base‐line mediums were achieved using neutralization (35.69 and 38.33% by P. stipitis ATCC 58784 and ATCC 58785, respectively) and charcoal (37.55% by P. stipitis ATCC 58785) detoxification methods. Results showed that the rice hull can be utilized as a good feedstock for ethanol production using P. stipitis. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:872–882, 2016  相似文献   
20.
Summary Surface of polystyrene beads was modified by poly(phe-lys) for invertase immobilisation. The optimum immobilisation conditions of invertase were; 0.01% (w/v) poly(phe-lys), 2% (v/v) glutaraldehyde at 25 °C and pH 4.5. The kinetics of sucrose hydrolysis by free and immobilised invertase in a batch reactor at pH 4.5 and 55 °C gave Km and Vmax values for sucrose with free and immobilised invertase of 81, 114 mM and 10.1, 9.2 mol glucose/min.mg enzyme, respectively. The deactivation rate constants of free and immobilised invertase were 0.0347 and 0.0098 min–1, respectively.  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