全文获取类型
收费全文 | 236篇 |
免费 | 17篇 |
出版年
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 26篇 |
2012年 | 23篇 |
2011年 | 11篇 |
2010年 | 15篇 |
2009年 | 10篇 |
2008年 | 14篇 |
2007年 | 7篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有253条查询结果,搜索用时 437 毫秒
191.
Jessie C. Tanner Jessica L. Ward Ruth G. Shaw Mark A. Bee 《Evolution; international journal of organic evolution》2017,71(7):1742-1754
Animal signals are complex, comprising multiple components that receivers may use to inform their decisions. Components may carry information of differing value to receivers, and selection on one component could modulate or reverse selection on another, necessitating a multivariate approach to estimating selection gradients. However, surprisingly few empirical studies have estimated the strength of phenotypic selection on complex signals with appropriate design and adequate power to detect nonlinear selection. We used phonotaxis assays to measure sexual selection on the advertisement signal of Cope's gray tree frog, Hyla chrysoscelis. Female preferences were assessed for five signal components using single‐ and two‐stimulus behavioral assays. Linear, quadratic, and correlational selection gradients were estimated from the single‐stimulus data. Significant directional selection is acting on call duration, call rate, pulse rate, and relative amplitude; stabilizing selection is acting on call duration and call rate. Under the two‐stimulus paradigm, conclusions were qualitatively different, revealing nonlinear selection on all components except call duration. For individual subjects, the outcomes of single‐ and two‐stimulus trials were frequently discordant, suggesting that the choice of testing paradigm may affect conclusions drawn from experiments. 相似文献
192.
The Development and Validation of the Osteoporosis Prevention and Awareness Tool (OPAAT) in Malaysia
Li Shean Toh Pauline Siew Mei Lai David Bin-Chia Wu Kok Thong Wong Bee Yean Low Claire Anderson 《PloS one》2015,10(5)
ObjectivesTo develop and validate Osteoporosis Prevention and Awareness Tool (OPAAT) in Malaysia.MethodsThe OPAAT was modified from the Malaysian Osteoporosis Knowledge Tool and developed from an exploratory study on patients. Face and content validity was established by an expert panel. The OPAAT consists of 30 items, categorized into three domains. A higher score indicates higher knowledge level. English speaking non-osteoporotic postmenopausal women ≥50 years of age and pharmacists were included in the study.ResultsA total of 203 patients and 31 pharmacists were recruited. Factor analysis extracted three domains. Flesch reading ease was 59.2. The mean±SD accuracy rate was 0.60±0.22 (range: 0.26-0.94). The Cronbach’s α for each domain ranged from 0.286-0.748. All items were highly correlated (Spearman’s rho: 0.761-0.990, p<0.05), with no significant change in the overall test-retest scores, indicating that OPAAT has achieved stable reliability. Pharmacists had higher knowledge score than patients (80.9±8.7vs63.6±17.4, p<0.001), indicating that the OPAAT was able to discriminate between the knowledge levels of pharmacists and patients.ConclusionThe OPAAT was found to be a valid and reliable instrument for assessing patient’s knowledge about osteoporosis and its prevention in Malaysia. The OPAAT can be used to identify individuals in need of osteoporosis educational intervention. 相似文献
193.
Beng Bee Oon Kit Yew Khong Malcolm W. Greaves Valerie M. Plummer 《BMJ (Clinical research ed.)》1974,2(5918):531
Skin and serum zinc measurements have been made in patients with leprosy with and without trophic skin ulceration and in several other groups. Serum zinc concentrations were decreased in leprosy irrespective of the presence or absence of skin ulceration. Serum zinc concentrations in leprosy were also unrelated to smears positive for Mycobacterium leprae and to the clinical type of leprosy. Since a decrease of the serum zinc was also found in patients with dermatitis herpetiformis and pulmonary tuberculosis it seems likely that the decreased serum zinc in leprosy is a nonspecific metabolic consequence of chronic skin and internal disease. The mean skin zinc concentration in leprosy did not differ significantly from the corresponding value in control subjects, the lack of agreement between serum and skin concentrations being possibly related to the presence of nonexchangeable keratin-bound zinc in skin. Though the clinical significance of lowered serum zinc concentrations in leprosy is uncertain therapeutic trials of zinc treatment in leprosy with trophic skin ulceration seem justifiable. 相似文献
194.
195.
Bee Ting Chan Noor Azuan Abu Osman Einly Lim Kok Han Chee Yang Faridah Abdul Aziz Amr Al Abed Nigel H. Lovell Socrates Dokos 《PloS one》2013,8(6)
Dilated cardiomyopathy (DCM) is the most common myocardial disease. It not only leads to systolic dysfunction but also diastolic deficiency. We sought to investigate the effect of idiopathic and ischemic DCM on the intraventricular fluid dynamics and myocardial wall mechanics using a 2D axisymmetrical fluid structure interaction model. In addition, we also studied the individual effect of parameters related to DCM, i.e. peak E-wave velocity, end systolic volume, wall compliance and sphericity index on several important fluid dynamics and myocardial wall mechanics variables during ventricular filling. Intraventricular fluid dynamics and myocardial wall deformation are significantly impaired under DCM conditions, being demonstrated by low vortex intensity, low flow propagation velocity, low intraventricular pressure difference (IVPD) and strain rates, and high-end diastolic pressure and wall stress. Our sensitivity analysis results showed that flow propagation velocity substantially decreases with an increase in wall stiffness, and is relatively independent of preload at low-peak E-wave velocity. Early IVPD is mainly affected by the rate of change of the early filling velocity and end systolic volume which changes the ventriculo:annular ratio. Regional strain rate, on the other hand, is significantly correlated with regional stiffness, and therefore forms a useful indicator for myocardial regional ischemia. The sensitivity analysis results enhance our understanding of the mechanisms leading to clinically observable changes in patients with DCM. 相似文献
196.
The morphology and histology, as well as the cytochemistry of complex carbohydrates, of the digestive system of Crypturellus tataupa (tataupa tinamou), Nothoprocta cinerascens (brushland tinamou), and Nothura maculosa (spotted tinamou) are described. The general morphology of the digestive system of these birds follows the basic model of the avian alimentary canal, although statistical analysis shows that the lengths of the organs are significantly different among the species. From cephalic to caudal regions the alimentary tract consists of esophagus, ingluvies or crop, proventriculus or glandular stomach, ventriculus or muscular stomach, small intestine, well-developed ceca, and rectum. Histologically, each section of the tract consists of four primary tissue layers: mucosa, submucosa, muscularis, and adventitia. Variations are found in the thickness of the esophageal epithelium, which shows the highest value in C. tataupa. In the proventriculus, the depth of the compound glands is greatest in N. cinerascens. The villi of the epithelial cells in the small intestine are most extensively developed in C. tataupa. Heterogeneity of mucins is detected not only in the surface coat of the alimentary tract but in the cellular content of the glands as well. Comparisons with the morphology of the digestive system of closely related and more advanced birds are made, and the possible relationship between morphological and cytochemical variation and the diet is discussed. © 1996 Wiley-Liss, Inc. 相似文献
197.
The mammalian carotid body is enlarged under conditions of chronic hypoxaemia. There has been some discussion as to whether this is due to hypertrophy or to hyperplasia. We have subjected rats to 1, 2 or 7 days of 10% oxygen and, 4 h before removing the carotid bodies, injected each animal with vincristine sulphate, an inhibitor of mitosis. The results of this study indicate that numerous mitoses can be found in the carotid bodies of rats exposed to 10% oxygen, but not in control animals maintained in air. These experiments thus provide direct evidence that at least a proportion of the increase in size of the carotid body induced by chronic hypoxaemia is due to a cellular hyperplasia. 相似文献
198.
Chin Chee Keong Stanly Christine Muniandy Asokan Ramanathan Surash Murugaiyah Vikneswaran Chew Bee Lynn Subramaniam Sreeramanan 《In vitro cellular & developmental biology. Plant》2021,57(6):874-882
In Vitro Cellular & Developmental Biology - Plant - Dendrobium hybrids have been cultivated as commercially important ornamental plants in the floriculture industry. However, the potential of... 相似文献
199.
Background
Research on the effects of dietary nutrients on respiratory health in human populations have not investigated curcumin, a potent anti-oxidant and anti-inflammatory compound present principally in turmeric used in large amounts in Asian curry meals.Objectives
To examine the association of curry intake with pulmonary function among smokers and non-smokers.Design
The frequency of curry intake, respiratory risk factors and spirometry were measured in a population-based study of 2,478 Chinese older adults aged 55 and above in the Singapore Longitudinal Ageing Studies.Results
Curry intake (at least once monthly) was significantly associated with better FEV1 (b = 0.045±0.018, p = 0.011) and FEV1/FVC (b = 1.14±0.52, p = 0.029) in multivariate analyses that controlled simultaneously for gender, age, height, height-squared, smoking, occupational exposure and asthma/COPD history and other dietary or supplementary intakes. Increasing levels of curry intake (‘never or rarely’, ‘occasional’, ‘often’, ‘very often’) were associated with higher mean adjusted FEV1 (p for linear trend = 0.001) and FEV1/FVC% (p for linear trend = 0.048). Significant effect modifications were observed for FEV1 (curry* smoking interaction, p = 0.028) and FEV1/FVC% (curry*smoking interaction, p = 0.05). There were significantly larger differences in FEV1 and FEV1/FVC% between curry intake and non-curry intake especially among current and past smokers. The mean adjusted FEV1 associated with curry intake was 9.2% higher among current smokers, 10.3% higher among past smokers, and 1.5% higher among non-smokers.Conclusion
The possible role of curcumins in protecting the pulmonary function of smokers should be investigated in further clinical studies. 相似文献200.
Tan Ching Ong Soo Hwee Lim Xiaowei Chen Siti Dahlia Mohd Dali Hugh Tiang Wah Tan Bee Wah Lee Fook Tim Chew 《Aerobiologia》2012,28(2):135-151
Monitoring atmospheric fern spore and pollen loads in Singapore was initiated in June 1990. Aside from the more numerous fungal
spores, fern spores and pollen grains made up 6.2–8.6% and 4.4–5.4% of the total airspora sampled, respectively. The most
frequently encountered fern spores, in descending order, were those of Nephrolepis
auriculata, Dicranopteris
linearis, Stenochlaena
palustris, Asplenium
nidus, Pteridium
aquilinum, and Dicranopteris
curranii. For pollen grains, the most frequently encountered, in descending order, were Elaeis
guineensis, Casuarina
equisetifolia, Acacia
auriculiformis, Kyllingia
polyphylla, Podocarpus, and Poaceae pollen grains. Seasonal patterns for individual fern spore or pollen types were discernible despite the relatively
uniform tropical climate in Singapore. The fern spore and pollen calendar for the period 1991–1995 was compared to that of
2005–2006 as a follow-up study to keep abreast with the rapidly changing landscape of Singapore. Diurnal patterns showing
a late morning to afternoon peak period were seen in fern spores, while the peak period was in the morning for pollen types
studied with the exception to oil palm pollen. Additionally, association between fern spore and pollen counts and local meteorological
conditions were also analyzed and found to be highly correlated. This study has thus identified the fern spores and pollen
airspora components, and determined the calendars, as well as diurnal profiles of the Singapore airspora and provides invaluable
information for allergy studies by highlighting the trigger sources present in the environment. 相似文献