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   98篇
  免费   2篇
  2018年   1篇
  2017年   2篇
  2015年   3篇
  2014年   1篇
  2013年   2篇
  2012年   3篇
  2010年   1篇
  2009年   3篇
  2008年   1篇
  2007年   2篇
  2006年   1篇
  2005年   3篇
  2004年   2篇
  2003年   5篇
  2002年   6篇
  2001年   13篇
  2000年   8篇
  1999年   2篇
  1998年   3篇
  1997年   5篇
  1996年   1篇
  1995年   3篇
  1992年   3篇
  1991年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1976年   4篇
  1975年   3篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
  1969年   2篇
  1968年   2篇
  1967年   1篇
排序方式: 共有100条查询结果,搜索用时 15 毫秒
71.
ERRATUM: Wright LE and Schwarcz HP (1998) Stable Carbon and Oxygen Isotopes in Human Tooth Enamel: Identifying Breastfeeding and Weaning in Prehistory. Am. J. Phys. Anthropol. 106: 1–18. Isotopic ratios were incorrectly printed as percentages (%) rather than units permil (‰). Wherever “breast feeding” and “breast fed” occur, the words should be combined into “breastfeeding” and “breastfed” respectively. The correct information on isotopic ratios is the following: p. 1, Abstract: all % signs should be “‰”; p. 2, column two, last line: “… δ13C values1, have been …”; p. 2, Footnote 1 should read: “Isotope ratios of carbon and oxygen are expressed in δ notation as follows, δ = [(Rsample/Rstandard) − 1] × 1000, where R = 13C/12C for δ13C, and R = 18O/16O for δ18O, and are in units permil, ‰.”; p. 3, column two: all % signs should be “‰”, except for the 23rd line from the bottom, which reads: “… provided 95% of water intake by all infants …”; p. 5: all % signs should be “‰”; p. 6, column one: 8th and 9th line from bottom should be “… mean deviations were 0.029‰ for δ13C and 0.024‰ for δ18O …”; p. 6, column one: 2nd line from bottom should be “… only 0.208‰ for δ13C and only 0.091‰ for δ18O …”; p. 6, column two: top line: “… of 0.5‰ in δ13C and 0.2‰ in δ18O …”; p. 8, 9 and 10: all % signs should be “‰”; p. 11, column two: 7th line from top: “… the lipids are 4-6‰ lighter …”; p. 12, 13 and 14: all % signs should be “‰.”  相似文献   
72.
73.

Background  

Hydrogenosomes are organelles that produce molecular hydrogen and ATP. The broad phylogenetic distribution of their hosts suggests that the hydrogenosomes of these organisms evolved several times independently from the mitochondria of aerobic progenitors. Morphology and 18S rRNA phylogeny suggest that the microaerophilic amoeboflagellate Psalteriomonas lanterna, which possesses hydrogenosomes and elusive "modified mitochondria", belongs to the Heterolobosea, a taxon that consists predominantly of aerobic, mitochondriate organisms. This taxon is rather unrelated to taxa with hitherto studied hydrogenosomes.  相似文献   
74.
Phage N5 is one of the phages of Vibrio cholerae serovar O1 biotype El Tor (Ghosh, A. N., Ansari, M. Q., and Dutta, G. C. Isolation and morphological characterization of El Tor cholera phages. J. Gen. Virol. 70: 2241–2243, 1989). In the present communication the growth curve, molecular weight and confirmation of the genome, partial denaturation map and restriction endonuclease digestion pattern have been determined. Partial denaturation map indicates that the genome has non-permuted / invariant sequence. Presence of cohesive ends has also been documented.  相似文献   
75.
Protein tyrosine phosphatase 1B (PTPN1) affects the regulation of insulin signaling and energy metabolism. We studied whether polymorphisms in the PTPN1 gene impact body fat distribution in the HERITAGE Family Study cohort in 502 white and 276 black subjects. Insulin sensitivity index, glucose disappearance index, acute insulin response to glucose (AIRglucose), and the disposition index (DI) were obtained from the frequently sampled intravenous glucose tolerance test. White subjects with the G82G at the PTPN1 IVS6+G82A polymorphism had higher body fat levels (p = 0.031) and sum of eight skinfolds (p = 0.003) and highest subcutaneous fat on the limbs (p = 0.002). G82A subjects had the lowest AIRglucose (p = 0.005) and disposition index (p = 0.040). Interaction effects between PTPN1 and leptin receptor gene variants influenced insulin sensitivity index and AIRglucose (p from 0.006 to 0.010). The variant PTPN1 Pro387Leu was associated with lower fasting insulin level (p = 0.035) and glucose disappearance index (p = 0.038). In summary, PTPN1 IVS6+G82G homozygotes showed higher levels of all measures of adiposity. G82 allele heterozygotes are potentially at higher risk for type 2 diabetes. Gene‐gene interactions between the PTPN1 and leptin receptor genes contributed to the phenotypic variability of insulin sensitivity. The PTPN1 Pro387Leu variant was associated with lower glucose tolerance.  相似文献   
76.
77.
Objective: To examine whether there is a major gene effect on fasting insulin and pleiotropic loci for fasting insulin, total fat mass (FM), and abdominal visceral fat (AVF). Research Methods and Procedures: A major gene hypothesis for fasting plasma insulin levels was assessed using segregation analyses of data on 495 members in 98 normolipidemic sedentary families of white descent who participated in the HERITAGE Family Study. Results: Segregation analyses were performed on insulin adjusted for age, on insulin adjusted for age and FM, and on insulin adjusted for age and AVF. Before adjustment for AVF and FM, a major gene effect on fasting insulin levels was indicated. The putative locus accounted for 54% of the variance under a recessive inheritance pattern, affecting 11% of the sample (i.e., allele frequency = 0.33). However, after adjusting for the effects of AVF or FM, neither a major effect alone nor a multifactorial component alone could be rejected, and support for a major gene was equivocal, i.e., neither the hypothesis of Mendelian τ values or that of the equal τs were rejected and the equal τ model fit the data better than the Mendelian τ model. This pattern (i.e., major gene evidence for insulin before but not after adjustment for AVF or FM) suggests that there is a putative locus with pleiotropic effects on both insulin and FM and another pleiotropic locus for both insulin and AVF. Discussion: Although these data do not directly support an additional major gene for insulin independent of AVF and FM, such support cannot be ruled out because there is still a significant major effect on FM‐ or AVF‐adjusted insulin (albeit the Mendelian nature of this effect is ambiguous).  相似文献   
78.
Body resistance and reactance to the conduction of an alternating electrical current were measured using electrodes attached to distal and proximal portions of limbs in anesthetized dogs. Body impedance was calculated from these measurements obtained at 30-min time intervals during a control period and after intravenous administration of 0.9% saline. Extracellular (ECW) and total body water (TBW) were determined by bromide and heavy water dilution techniques, respectively. Baseline impedance obtained from proximal electrodes was related to ECW (r = 0.95, P less than 0.001) and TBW (r = 0.80, P less than 0.02). After saline infusion, proximal electrodes detected a significant fall in impedance (P less than 0.001), whereas distal electrodes did not (P = 0.06). Furthermore, ECW and TBW could be estimated from the drop of proximal impedance after this bolus infusion (r = 0.82, P less than 0.02, and r = 0.86, P less than 0.01, respectively), but not from distal impedance measurements. Proximally placed impedance electrodes are superior to traditionally used distal electrodes for assessment of body fluid changes in the dog.  相似文献   
79.
Thirty-three dairy farms in the Norwegian counties of ?stfold and Akershus in which cubicle sheds had been in use for at least one year and with a herd size of less than 60 cows, were contacted and asked to participate in a study. The study focused on heifers' use of cubicles and concentrate dispenser just after being transferred from rearing accommodation to the milking herd. For each heifer, the farmer recorded cubicle use once nightly between 9 and 11 pm. The daily amount of concentrate released in the dispenser and the allotted daily ration were also recorded. The recording period was 15 consecutive days for cubicle use and 7 days for concentrate dispenser use. Cubicle refusal behaviour, i.e. lying outside the cubicles, was analysed by logistic regression using rearing accommodation of heifers, herd size, heifer age, and housing layout as independent variables, and herd as a clustering variable. On Day 2 after transfer, 34% of the heifers were showing cubicle refusal behaviour (N = 340). By Day 15 this percentage had dropped to 23. Cubicle refusal was lower throughout the whole period among heifers which used the cubicles on the 3 first days after transfer compared to those which did not. This tendency could also be detected several months later. The analysis showed cubicle refusal to be significantly associated with rearing accommodation (OR = 6.1, c.i.95%OR = 1.5–24.3, P = 0.01) and cubicle layout in the shed (OR = 0.2, c.i.95%OR = 0.0–0.7, P = 0.01). None of the tested variables were found to be significant for failure to use the concentrate dispenser, a behaviour which was less frequent than cubicle refusal. However, 8 percent of the heifers did not visit the dispenser at all throughout the 7 days of observation.  相似文献   
80.
We investigated whether the Arg16Gly and Gln27Glu polymorphisms of the β2‐adrenergic receptor gene were associated with body‐fat and fat‐distribution phenotypes measured before and in response to a 20‐week endurance‐training program. BMI, fat mass (FAT), percentage of body fat (%FAT), sum of eight skinfolds (SF8), and abdominal fat areas assessed by computed tomography were measured in adult sedentary white and black participants of the HERITAGE Family Study. Evidence of gene‐by‐obesity interaction was found in whites for several adiposity phenotypes measured before training. Analyses performed separately in nonobese and obese subjects revealed that obese men carrying the Glu27 allele have lower fat accumulation (BMI, FAT, and %FAT) than noncarriers. Among white obese women, Gly16Gly homozygotes had a lower fat accumulation (BMI, FAT, and SF8) than Arg16Gly and Arg16Arg carriers. In response to endurance training, white women with the Arg16Arg genotype exhibited a greater reduction in BMI, FAT, and %FAT. Results observed in blacks were mostly negative. These results suggest that polymorphisms in the β2‐adrenergic receptor gene influence the amount of body fat in white obese men (Gln27Glu) and women (Arg16Gly), as well as the changes in adiposity in response to endurance training in white women (Arg16Gly).  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