全文获取类型
收费全文 | 1321篇 |
免费 | 120篇 |
国内免费 | 1篇 |
专业分类
1442篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 17篇 |
2020年 | 14篇 |
2019年 | 17篇 |
2018年 | 13篇 |
2017年 | 22篇 |
2016年 | 35篇 |
2015年 | 60篇 |
2014年 | 60篇 |
2013年 | 71篇 |
2012年 | 94篇 |
2011年 | 89篇 |
2010年 | 63篇 |
2009年 | 56篇 |
2008年 | 77篇 |
2007年 | 78篇 |
2006年 | 65篇 |
2005年 | 80篇 |
2004年 | 75篇 |
2003年 | 82篇 |
2002年 | 51篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 14篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 4篇 |
排序方式: 共有1442条查询结果,搜索用时 0 毫秒
61.
Christopher Williams Philip Wilson Jill Morrison Alex McMahon Walker Andrew Lesley Allan Alex McConnachie Yvonne McNeill Louise Tansey 《PloS one》2013,8(1)
Background
Access to Cognitive behavioural therapy (CBT) for depression is limited. One solution is CBT self-help books. Trial Objectives: To assess the impact of a guided self-help CBT book (GSH-CBT) on mood, compared to treatment as usual (TAU).Hypotheses:- GSH-CBT will have improved mood and knowledge of the causes and treatment of depression compared to the control receiving TAU
- Guided self-help will be acceptable to patients and staff.
Methods and Findings
Participants: Adults attending seven general practices in Glasgow, UK with a BDI-II score of ≥14. 141 randomised to GSH-CBT and 140 to TAU. Interventions: RCT comparing ‘Overcoming Depression: A Five Areas Approach’ book plus 3–4 short face to face support appointments totalling up to 2 hours of guided support, compared with general practitioner TAU. Primary outcome: The BDI (II) score at 4 months. Numbers analysed: 281 at baseline, 203 at 4 months (primary outcome), 117 at 12 months. Outcome: Mean BDI-II scores were lower in the GSH-CBT group at 4 months by 5.3 points (2.6 to 7.9, p<0.001). At 4 and 12 months there were also significantly higher proportions of participants achieving a 50% reduction in BDI-II in the GSH-CBT arm. The mean support was 2 sessions with 42.7 minutes for session 1, 41.4 minutes for session 2 and 40.2 minutes of support for session 3. Adverse effects/Harms: Significantly less deterioration in mood in GSH-CBT (2.0% compared to 9.8% in the TAU group for BDI—II category change).Limitations
Weaknesses: Our follow-up rate of 72.2% at 4 months is better than predicted but is poorer at 12 months (41.6%). In the GSH-CBT arm, around 50% of people attended 2 or fewer sessions. 22% failed to take up treatment.Conclusions
GSH-CBT is substantially more effective than TAU.Trial Registration
Controlled-Trials.com ISRCTN13475030 相似文献62.
Change in Dietary Patterns and Change in Waist Circumference and DXA Trunk Fat Among Postmenopausal Women
下载免费PDF全文
![点击此处可从《Obesity (Silver Spring, Md.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
63.
Stefanie M. Hixson Kruti Shukla Lesley G. Campbell Rebecca H. Hallett Sandy M. Smith Laurence Packer Michael T. Arts 《PloS one》2016,11(3)
Nutritional enhancement of crops using genetic engineering can potentially affect herbivorous pests. Recently, oilseed crops have been genetically engineered to produce the long-chain omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at levels similar to that found in fish oil; to provide a more sustainable source of these compounds than is currently available from wild fish capture. We examined some of the growth and development impacts of adding EPA and DHA to an artificial diet of Pieris rapae, a common pest of Brassicaceae plants. We replaced 1% canola oil with EPA: DHA (11:7 ratio) in larval diets, and examined morphological traits and growth of larvae and ensuing adults across 5 dietary treatments. Diets containing increasing amounts of EPA and DHA did not affect developmental phenology, larval or pupal weight, food consumption, nor larval mortality. However, the addition of EPA and DHA in larval diets resulted in progressively heavier adults (F 4, 108 = 6.78; p = 0.011), with smaller wings (p < 0.05) and a higher frequency of wing deformities (R = 0.988; p = 0.001). We conclude that the presence of EPA and DHA in diets of larval P. rapae may alter adult mass and wing morphology; therefore, further research on the environmental impacts of EPA and DHA production on terrestrial biota is advisable. 相似文献
64.
Janina Kaluza R. Lesley Donald Ian C. Gynther Luke K-P. Leung Benjamin L. Allen 《PloS one》2016,11(1)
The water mouse is a small and vulnerable rodent present in coastal areas of south-west Papua New Guinea, and eastern Queensland and the Northern Territory of Australia. Current knowledge regarding the distribution of the water mouse is incomplete and the loss of one local population has been documented in southeast Queensland, a region where pressures from urban and industrial development are increasing. Water mouse populations have not been studied intensively enough to enable the primary factors responsible for the local decline to be identified. We surveyed the distribution and density of the water mouse along the Maroochy River of southeast Queensland, near the southern extent of the species’ range, to gather baseline data that may prove valuable for detecting any future decline in this population’s size or health. All areas of suitable habitat were surveyed on foot or by kayak or boat over a three-year period. We found 180 water mouse nests, of which ~94% were active. Permanent camera monitoring of one nest and limited supplementary live trapping suggested that up to three individual mice occupied active nests. Water mouse density was estimated to be 0.44 per hectare of suitable habitat along the Maroochy River. Should future monitoring reveal an adverse change in the water mouse population on the Maroochy River, a concerted effort should be made to identify contributing factors and address proximate reasons for the decline. 相似文献
65.
Gray level Co‐occurrence Matrices (GLCM) to assess microstructural and textural changes in pre‐implantation embryos
下载免费PDF全文
![点击此处可从《Molecular reproduction and development》网站下载免费的PDF全文](/ch/ext_images/free.gif)
66.
67.
Qingping Xu Matthew Biancalana Joanna C. Grant Hsiu‐Ju Chiu Lukasz Jaroszewski Mark W. Knuth Scott A. Lesley Adam Godzik Marc‐Andr Elsliger Ashley M. Deacon Ian A. Wilson 《Protein science : a publication of the Protein Society》2019,28(9):1676-1689
Free‐standing single‐layer β‐sheets are extremely rare in naturally occurring proteins, even though β‐sheet motifs are ubiquitous. Here we report the crystal structures of three homologous, single‐layer, anti‐parallel β‐sheet proteins, comprised of three or four twisted β‐hairpin repeats. The structures reveal that, in addition to the hydrogen bond network characteristic of β‐sheets, additional hydrophobic interactions mediated by small clusters of residues adjacent to the turns likely play a significant role in the structural stability and compensate for the lack of a compact hydrophobic core. These structures enabled identification of a family of secreted proteins that are broadly distributed in bacteria from the human gut microbiome and are putatively involved in the metabolism of complex carbohydrates. A conserved surface patch, rich in solvent‐exposed tyrosine residues, was identified on the concave surface of the β‐sheet. These new modular single‐layer β‐sheet proteins may serve as a new model system for studying folding and design of β‐rich proteins. 相似文献
68.
Objective: To examine the relationship between children's overweight status and other cardiovascular risk fitness factors and academic performance among fifth‐grade students. Research Methods and Procedures: Using a sample of 968 fifth‐grade students (50.7% boys; mean age = 10.6 years), children's cardiovascular risks (BMI, blood pressure, acanthosis nigricans) and fitness measures were compared with their mean group performance scores across four subscales (mathematics, reading/language arts, science, and social studies) of a statewide standardized academic performance test. Results: Of this sample, 39% were either at risk for being overweight or were already overweight; slightly over one half were of normal weight. Initial findings revealed a significant relationship between children's weight category and their reading/language arts, mathematics, and science test scores even after controlling for a proxy of socioeconomic status. When additional cardiovascular risk and fitness measures were included in the model, however, children's BMI status had no association. Instead, a composite fitness index, children's blood pressure, sex, and proxy of socioeconomic status were significantly associated with children's academic test scores. Discussion: This study expanded our understanding of the connection between children's overweight risks and academic performance by examining the impact of other cardiovascular risk factors such as high blood pressure and measures of fitness. These findings support the development and implementation of childhood cardiovascular risk surveillance programs that evaluate not only children's overweight risks but also their fitness, risk for type 2 diabetes, and/or high blood pressure by showing a relationship between some of these risks and children's academic test performance. 相似文献
69.
Strand AD Aragaki AK Baquet ZC Hodges A Cunningham P Holmans P Jones KR Jones L Kooperberg C Olson JM 《PLoS genetics》2007,3(4):e59
Many neurodegenerative diseases have a hallmark regional and cellular pathology. Gene expression analysis of healthy tissues may provide clues to the differences that distinguish resistant and sensitive tissues and cell types. Comparative analysis of gene expression in healthy mouse and human brain provides a framework to explore the ability of mice to model diseases of the human brain. It may also aid in understanding brain evolution and the basis for higher order cognitive abilities. Here we compare gene expression profiles of human motor cortex, caudate nucleus, and cerebellum to one another and identify genes that are more highly expressed in one region relative to another. We separately perform identical analysis on corresponding brain regions from mice. Within each species, we find that the different brain regions have distinctly different expression profiles. Contrasting between the two species shows that regionally enriched genes in one species are generally regionally enriched genes in the other species. Thus, even when considering thousands of genes, the expression ratios in two regions from one species are significantly correlated with expression ratios in the other species. Finally, genes whose expression is higher in one area of the brain relative to the other areas, in other words genes with patterned expression, tend to have greater conservation of nucleotide sequence than more widely expressed genes. Together these observations suggest that region-specific genes have been conserved in the mammalian brain at both the sequence and gene expression levels. Given the general similarity between patterns of gene expression in healthy human and mouse brains, we believe it is reasonable to expect a high degree of concordance between microarray phenotypes of human neurodegenerative diseases and their mouse models. Finally, these data on very divergent species provide context for studies in more closely related species that address questions such as the origins of cognitive differences. 相似文献
70.
Robert N. L. Fitt Steve Palmer Casey Hand Justin M. J. Travis Lesley T. Lancaster 《Ecography》2019,42(1):201-210
Many species are undergoing distributional shifts in response to climate change. However, wide variability in range shifting rates has been observed across taxa, and even among closely‐related species. Attempts to link climate‐mediated range shifts to traits has often produced weak or conflicting results. Here we investigate interactive effects of developmental processes and environmental stress on the expression of traits relevant to range shifts. We use an individual‐based modelling approach to assess how different developmental strategies affect range shift rates under a range of environmental conditions. We find that under stressful conditions, such as at the margins of the species’ fundamental niche, investment in prolonged development leads to the greatest rates of range shifting, especially when longer time in development leads to improved fecundity and dispersal‐related traits. However, under benign conditions, and when traits are less developmentally plastic, shorter development times are preferred for rapid range shifts, because higher generational frequency increases the number of individual dispersal events occurring over time. Our results suggest that the ability of a species to range shift depends not only on their dispersal and colonisation characteristics but also how these characteristics interact with developmental strategies. Benefits of any trait always depended on the environmental and developmental sensitivity of life history trait combinations, and the environmental conditions under which the range shift takes place. Without considering environmental and developmental sources of variation in the expression of traits relevant to range shifts, there is little hope of developing a general understanding of intrinsic drivers of range shift potential. 相似文献