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   270篇
  免费   9篇
  2023年   2篇
  2022年   3篇
  2021年   9篇
  2020年   4篇
  2019年   11篇
  2018年   6篇
  2017年   4篇
  2016年   8篇
  2015年   8篇
  2014年   14篇
  2013年   15篇
  2012年   25篇
  2011年   27篇
  2010年   7篇
  2009年   9篇
  2008年   19篇
  2007年   11篇
  2006年   19篇
  2005年   15篇
  2004年   8篇
  2003年   9篇
  2002年   5篇
  2001年   9篇
  2000年   6篇
  1999年   2篇
  1998年   5篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1978年   1篇
  1974年   1篇
  1967年   2篇
排序方式: 共有279条查询结果,搜索用时 15 毫秒
1.
2.
DNA haplotype analyses of patients with hyperphenylalaninemia.   总被引:1,自引:1,他引:0       下载免费PDF全文
Linkage analysis of phenylketonurics has shown a strong association between the DNA haplotype at the phenylalanine hydroxylase (PAH) locus and phenylketonuria (PKU). Similarly, a genetic linkage between less severe forms of hyperphenylalaninemia (HPA) and the PAH locus has been suggested. In the present study we analyzed this linkage in more detail. Haplotypes at the PAH locus were determined for 19 individuals with moderately elevated plasma phenylalanine and normal urinary neopterin/biopterin ratios. Fourteen of these individuals had plasma phenylalanine levels of 4-10 mg/dl (mild HPA), and the other five had plasma phenylalanine levels of 10-19 mg/dl (atypical PKU). Thirteen of the 15 HPA families consisted of an affected child and at least one other sibling. Elevated plasma phenylalanine was seen to genetically segregate with specific PAH alleles in each family. Summation of the LOD scores for both categories of moderate plasma phenylalanine elevation gave a maximum value of 3.556 at theta = 0. At theta = 0 this gives a probability of linkage between the PAH locus and the locus for moderate phenylalanine elevations that is approximately 3,600:1. None of the alleles segregating with either mild HPA or atypical PKU were of haplotype 2 or 3, and 13/20 were of types 1 or 4. This is in agreement with the most deleterious mutations being on haplotypes 2 and 3 and with the less severe mutations being on haplotypes 1 and 4. chi 2 Analyses indicated no statistically significant correlation between HPA and a particular haplotype or restriction-enzyme site.  相似文献   
3.
The built environment is the largest single emitter of CO2 and an important consumer of energy. Much research has gone into the improved efficiency of building operation and construction products. Life Cycle Assessment (LCA) is commonly used to assess existing buildings or building products. Classic LCA, however, is not suited for evaluating the environmental performance of developing technologies. A new approach, anticipatory LCA (a‐LCA), promises various advantages and can be used as a design constraint during the product development stage. It helps overcome four challenges: (i) data availability, (ii) stakeholder inclusion, (iii) risk assessment, and (iv) multi‐criteria problems. This article's contribution to the line of research is twofold: first, it adapts the a‐LCA approach for construction‐specific purposes in theoretical terms for the four challenges. Second, it applies the method to an innovative prefabricated modular envelope system, the CleanTechBlock (CTB), focusing on challenge (i). Thirty‐six CTB designs are tested and compared to conventional walls. Inclusion of technology foresight is achieved through structured scenario analysis. Moreover, challenge (iv) is tackled through the analysis of different environmental impact categories, transport‐related impacts, and thickness of the wall assemblies of the CTB. The case study results show that optimized material choice and product design is needed to reach the lowest environmental impact. Methodological findings highlight the importance of context‐specific solutions and the need for benchmarking new products.  相似文献   
4.
The present study was undertaken to determine in vivo and in vitro effects of some plant growth regulators on rat erythrocyte carbonic anhydrase (CA) and glucose-6-phosphate dehydrogenase (G6PD) activities. Both in vivo and in vitro, spermidine and kinetin did not affect enzymatic activities of CA and G6PD, whereas putrescine decreased these activities, and abscisic acid increased them. Since plants use such growth regulators, their effects should be considered on mammals consuming them since they may possess important biological effects.  相似文献   
5.
6.
A case-control study on the morbidity of Chagas heart disease was carried out in the municipality of Barcelos in the microregion of the Rio Negro, state of Amazonas. One hundred and six individuals, who were serologically positive for Trypanosoma cruzi infection, as confirmed by at least two techniques with different principles, were matched according to age and sex with an equal number of seronegative individuals. The cases and controls were evaluated using an epidemiological questionnaire and clinical, electrocardiograph and echocardiograph examinations. In the seroepidemiological evaluation, 62% of the interviewees recognised triatomines and most of them confirmed that they had seen these insects in the piassava plantations of the riverside communities of the Negro River tributaries. Of the seropositive patients, 25.8% affirmed that they had been stung by the triatomines and 11.7% denied having been stung. The principal clinical manifestations of the seropositive individuals were palpitations, chest pain and dyspnoea upon effort. Cardiac auscultation revealed extrasystoles, bradycardia and systolic murmurs. The electrocardiographic alterations were ventricular extrasystoles, left and right bundle branch block, atrioventricular block and primary T wave alterations. The echocardiogram was altered in 22.6% of the seropositive individuals and in 8.5% of the seronegative individuals.  相似文献   
7.
Additional evidence about the influence of the cell wall physical and chemical characteristics on protein extractability was determined by calculating the conversion factors of five different microalgae known to have different cell wall composition, and their protein extracts. The conversion factors obtained for crude rigid cell walled Chlorella vulgaris, Nannochloropsis oculata and Haematococcus pluvialis were 6.35, 6.28 and 6.25, respectively, but for their protein extracts the values were lower with 5.96, 5.86 and 5.63. On the other hand, conversion factor obtained for fragile cell walled microalgae Porphyridium cruentum and Athrospira platensis was 6.35 for the former and 6.27 for the latter, with no significant difference for their protein extract with 6.34 for the former and 6.21 for the latter. In addition, the highest hydro-soluble protein percentage recovered from total protein was for P. cruentum 80.3 % and A. platensis 69.5 % but lower for C. vulgaris with 43.3 %, N. oculata with 33.3 % and H. pluvialis with 27.5 %. The study spotted the light on the influence of the cell wall on evaluating the conversion factor and protein extractability. In addition, it showed the necessity of finding the conversion factor every time accurate protein quantification is required, and proved that there is not a universal conversion factor that can be recommended.  相似文献   
8.
Can ideology, as a widespread “expectation creator,” impact economic decisions? In two studies we investigated the influence of the Benevolent Sexism (BS) ideology (which dictates that men should provide for passive and nurtured women) on women’s economic decision-making. In Study 1, using a Dictator Game in which women decided how to share amounts of money with men, results of a Generalized Linear Mixed Model analysis show that higher endorsement of BS and contextual expectations of benevolence were associated with more very unequal offers. Similarly, in an Ultimatum Game in which women received monetary offers from men, Study 2’s Generalized Linear Mixed Model’s results revealed that BS led women to reject more very unequal offers. If women’s endorsement of BS ideology and expectations of benevolence prove contrary to reality, they may strike back at men. These findings show that BS ideology creates expectations that shape male-female relationships in a way that could be prejudicial to men.  相似文献   
9.
10.
Phytochemistry Reviews - Cynara cardunculus health benefits have aroused much interest, leading to the discovery of valuable bioactive compounds with a crucial role in plant defence. Guaianolides...  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