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   131篇
  免费   12篇
  国内免费   118篇
  2021年   6篇
  2020年   4篇
  2019年   1篇
  2018年   3篇
  2017年   4篇
  2016年   3篇
  2015年   5篇
  2014年   18篇
  2013年   22篇
  2012年   6篇
  2011年   10篇
  2010年   1篇
  2009年   4篇
  2008年   11篇
  2007年   13篇
  2006年   8篇
  2005年   31篇
  2004年   15篇
  2003年   6篇
  2002年   9篇
  2001年   7篇
  2000年   1篇
  1999年   12篇
  1998年   8篇
  1997年   9篇
  1996年   7篇
  1995年   9篇
  1994年   4篇
  1993年   5篇
  1992年   6篇
  1991年   2篇
  1990年   5篇
  1989年   3篇
  1988年   2篇
  1985年   1篇
排序方式: 共有261条查询结果,搜索用时 78 毫秒
11.
12.
Topical application of the Metarhizium anisopliae var. acridum specialist strain CQMa 102 to the locust Locusta migratoria manilensis results in changes of the concentrations of trehalose and glucose in the haemolymph. Micrographs of the locust haemolymph shows Metarhizium anisopliae can effectivly penetrate the external skeleton of locust and after 2 days infection, the hyphae body will appear in the haemolymph of infected insects. The time in decrease of trehalose concentration coincided with that in increase of trehalose-hydrolysing enzyme activity in the haemolymph of the fungus-infected insects. Overlay gel analysis indicated there was considerably more trehalose-hydrolysing activity in the haemolymph of locusts infected by fungus than in controls. A comparable isoform was identified in in vitro culture of the fungus, suggesting a fungal origin for the in vivo enzyme. Haemolymph trehalose decreased significantly during mycosis of locusts by M. anisopliae. All these results suggested that this fungus may take advantage of competing nutrient utilization against the insect by its trehalose-hydrolyzing enzyme secretion. It may provide fundamental knowledge for fungal pathogenesis.  相似文献   
13.
细胞色素P450 2D6缺陷型等位基因的家系分析   总被引:2,自引:1,他引:1  
利用等位基因特民扩增法(ASA)为基础的基因分型法,对细胞色素P4502D6 (CYP2D6)缺陷型等位基因携带者的9个家庭共38个进行了基因分型,并与用右旋美沙芬为 探针的表型分型法进行对比,发现两种方法的结果是一致的,CYP2D6酶缺陷型等位基因呈常染色体隐性遗传。 Abstract:A genotyping method based on the principle of allele-specific amplification and a phenotyping procedure with dextromethorphan as a probe were employed in familial study of nine families with 38 members for the cytochrome P450 2D6(CYP2D6)deficient alleles——CYP2D6A,CYP2D6B,CYP2D6D and CYP2D6T.The results showed that the CYP2D6 deficient alleles were inherited as an autosomal recessive trait.  相似文献   
14.
microRNA及其应用前景   总被引:6,自引:0,他引:6  
microRNA(miRNA)是近年发现的以序列特异性方式调控基因表达的一个非编码蛋白质的大约包含21~22个核苷酸的小RNA家族。研究表明,miRNA参与多种生物学过程,包括发育、分化、凋亡、脂肪代谢、病毒感染和癌症等。因此,揭示miRNA在细胞中的作用,将会给基因功能和基因治疗的研究带来新的机遇。  相似文献   
15.
1植物名称美洲冬青[Ilex verticillata (Linn.) A.Gray],由美国缅因大学张冬林博士提供。2材料类别带腋芽的嫩茎段。3培养条件启动培养基:(1)MS 6-BA0.5mg·L-1(单位下同) IBA0.1。增殖与壮苗培养基:(2)MS 6-BA1.0 NAA0.5;(3)MS KT1.0 NAA0.5;  相似文献   
16.
Reproduction is the highest energy demand period for small mammals, during which both energy intake and expenditure are increased to cope with elevated energy requirements of offspring growth and somatic protection. Oxidative stress life history theory proposed that reactive oxygen species(ROS) were produced in direct proportion to metabolic rate, resulting in oxidative stress and damage to macromolecules. In the present study, several markers of oxidative stress and antioxidants activities were examined in brain, liver, kidneys, skeletal muscle and small intestine in non-lactating(Non-Lac) and lactating(Lac) KM mice. Uncoupling protein(ucps) gene expression was examined in brain, liver and muscle. During peak lactation, gross energy intake was 254% higher in Lac mice than in Non-Lac mice. Levels of H2O2 of Lac mice were 17.7% higher in brain(P<0.05), but 21.1%(P<0.01) and 14.5%(P<0.05) lower in liver and small intestine than that of Non-Lac mice. Malonadialdehyde(MDA) levels of Lac mice were significantly higher in brain, but lower in liver, kidneys, muscle and small intestine than that of Non-Lac mice. Activity of glutathione peroxidase(GSH-PX) was significantly decreased in brain and liver in the Lac group compared with that in the Non-Lac group. Total antioxidant capacity(TAOC) activity of Lac mice was significantly higher in muscle, but lower in kidneys than Non-Lac mice. Ucp4 and ucp5 gene expression of brain was 394% and 577% higher in Lac mice than in Non-Lac mice. These findings suggest that KM mice show tissuedependent changes in both oxidative stress and antioxidants. Activities of antioxidants may be regulated physiologically in response to the elevated ROS production in several tissues during peak lactation. Regulations of brain ucp4 and ucp5 gene expression may be involved in the prevention of oxidative damage to the tissue.  相似文献   
17.
1,4-β-D-glucan cellobiohydrolase I (CBH I),p-nitrophenyl β-D-cellobioside,p-nitrophenol andcellobiose show distinct ultraviolet spectra,allowing the design of an assay to track the dynamic process ofp-nitrophenyl β-D-cellobioside hydrolysis by CBH I.Based on the linear relationship between p-nitrophenolformation in the hydrolysate and its first derivative absorption Curve of AUC340_400_(nm)(area under the curve),a new sensitive assay for the determination of CBH I activity was developed.The dynamic parameters ofcatalysis reaction,such as Vm and k_(cat),can all be derived from this result.The influence of β-glucosidase andendoglucanase in crude enzyme sample on the assay was discussed in detail.This approach is useful foraccurate determination of the activity of CBHs.  相似文献   
18.
To investigate the distribution of hepatitis B virus (HBV) genotypes and subgenotypes among the Bai nationality in Dali, a total of 100 serum samples from patients with chronic HBV-infection were collected for the detection of HBV genotypes and subgenotypes by genotype-specific primers and restriction fragment length polymorphism (RLFP), respectively. Among the 100 samples, the proportions of genotype B, C and mixed genotype (B+C) were 41%, 25% and 34%, respectively. All the genotype B strains belonged to subgenotype Ba In genotype C, 84% were Subgenotype Cs and 12% were subgenotype Ce. The distribution of genotypes B, C and B+C showed no significant difference between male and female patients (P=0.182) and among the age groups of patients (P=0.812). The rates of HBeAg/HBeAg positivity were no significantly different among genotypes B, genotype C and mixed genotype (B+C) (P=0.077/P=0.663). In Dali, genotypes B, B+C and C existed among Bai nationality with chronic HBV-infection, and genotype B was the major genotype. Subgenotypes Ba and Cs were the predominant strains in patients with HBV genotype B/C infection. The most prominent characteristic was the higher prevalent rate of mixed genotype (B+C) in patients.  相似文献   
19.
20.
1 INTRODUCTION Bailong River valley is situated in the south of Gansu Province and northeast of Qinghai-Tibet Plateau at longitudes of 101°40'-105°20' E and latitudes of 32°21'-35°50' N.The mean annual precipitation is 448.9-911.6ram and the mean annual temperature 4.7℃-12.7℃.The drainage area has an elevation from 550m to 4920m.The complex habitats give rise to a variety of forest communities and varied patterns of ecosystems.  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