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41.
Nodules found in the superficial tissues of laboratory-maintained snails (Bulinus jousseaumei) contained a bacterium of two forms. This nonmotile microorganism occurred in intracellular packets as a simple gram-negative rod that appeared to undergo intrapacket transition to a cephalotrichous form. The latter is characterized by a "head" from which emerge long, thick, rigid, flagella-like, helically constituted filamentous organelles with a core and an outer component that is not an extension of the bacterial envelope. Neither form was successfully cultured, but clean snails derived from eggs removed before hatching developed nodules within 1 to 3 months of exposure to infected snails. The infectivity was specific for the host snail, and no transmission occurred to snails of 5 other genera tested. The presence of nodules did not interfere with longevity or reproduction of infected snails. Details of infectivity, transition, and taxonomic position of the bacterium remain to be explored, but it is reported because of unique morphological and ultrastructural features not previously known. 相似文献
42.
Loss of phylogenetic information in chorion gene families of Bombyx mori gene conversion 总被引:1,自引:0,他引:1
Regier JC; Weigmann BM; Leclerc RF; Friedlander TP 《Molecular biology and evolution》1994,11(1):72-87
The silkmoth chorion has provided a stimulating model for the study of
evolution and developmental regulation of gene families. Previous attempts
at inferring relationships among chorion sequences have been based on
pairwise comparisons of overall similarity, a potentially problematic
approach. To remedy this, we identified the alignable regions of low
sequence variability and then analyzed this restricted database by
parsimony and neighbor-joining methods. At the deepest level, the chorion
sequence tree is split into two branches, called "alpha" and "beta." Within
each branch, early- and late-expressing genes each constitute monophyletic
groups, while the situation with middle-expressing genes remains uncertain.
The HcB gene family appears to be the most basal beta-branch group, but
this conclusion is qualified because the effect of gene conversion on
branching order is unknown. Previous studies by Eickbush and colleagues
have strongly suggested that ErA, HcA, and HcB families undergo gene
conversion within a gene family, whereas the ErB family does not. The
occurrence of conversion correlates with a particular tree structure;
namely, branch lengths are much greater at the base of the family than at
higher internodes and terminal branches. These observations raise the
possibility that chorion gene families are defined by gene conversion
events (reticulate evolution) rather than by descent with modification
(synapomorphy).
相似文献
43.
Barry M. Popkin Sahasporn Paeratakul Fengying Zhai Keyou Ge 《Obesity (Silver Spring, Md.)》1995,3(Z2):145s-153s
The relationships between dietary and environmental factors and obesity are reviewed. Findings from selected population studies of diet and body weight are presented. In general, the results from population studies of diet and obesity have been inconsistent and marked with methodological weaknesses, especially the use of cross-sectional study design. Apart from the diet, several social and economic factors appear to be important correlates of obesity in the population. However, most studies have focused on the socioeconomic status as abroad, composite measure. The relationships between income, education, occupation, place of residence, and obesity are reviewed here, with emphasis on the developing countries. In many developing countries, the changing dietary pattern, along with rising life expectancy and changing socioeconomic environment, has contributed to the increasing problems of obesity and other diet-related chronic diseases that will have an enormous impact on the health and health care resource of these countries in the near future. 相似文献
44.
Takasaki Y.; Orr D.; Popkin J.; Xie A. L.; Bradley T. D. 《Journal of applied physiology》1989,67(5):1776-1784
We studied the electromyographic activity of the diaphragm (EMGdi) and abdominal external oblique (EMGeo) muscles in response to progressive hypercapnia (HCVR) and hypoxia (HVR) in five normal males. The slopes of the regression lines relating log EMGdi activity to minute volume of ventilation (VE) were steeper during HVR runs than HCVR runs (mean +/- SE, 0.03201 +/- 0.00724 vs. 0.02729 +/- 0.00676, P less than 0.03). Phasic expiratory EMGeo activity was seen in 15 of 15 HCVR runs but in only 6 of 15 HVR runs. Furthermore, the maximum level of VE attained before the onset of EMGeo activity was significantly lower during HCVR runs than during HVR runs (23.1 +/- 2.5 vs. 34.8 +/- 4.01/min, P less than 0.003). We conclude that in awake humans 1) the diaphragm is activated to a greater extent by hypoxia than hypercapnia at a given VE and 2) hypercapnia causes a more consistent recruitment of abdominal expiratory activity at lower VE than does hypoxia. 相似文献
45.
46.
A significant increase occurred in the initiation and duration of breast-feeding among Honduran women between 1981 and 1987. Changes in population characteristics (e.g. level of education of women) would be expected to lead to a decrease in breast-feeding at each infant age, but these were offset by behavioural changes that led to an increase in the likelihood of initiation and continuation of breast-feeding. An exploration of relevant factors suggests that the PROALMA breast-feeding promotion programme has had a profound effect on the breast-feeding behaviour of Honduran mothers. 相似文献
47.
Ingar M Zielinski Marijtje LA Jongsma C Marjolein Baas Pauline BM Aarts Bert Steenbergen 《BMC neurology》2014,14(1):1-9
Background
In a subset of children with unilateral Cerebral Palsy (CP) a discrepancy between capacity and performance of the affected upper limb can be observed. This discrepancy is known as Developmental Disregard (DD). Though the phenomenon of DD has been well documented, its underlying cause is still under debate. DD has originally been explained based on principles of operant conditioning. Alternatively, it has been proposed that DD results from a diminished automaticity of movements, resulting in an increased cognitive load when using the affected hand. To investigate the amount of involved cognitive load we studied Event-Related Potentials (ERPs) preceding task-related motor responses during a single-hand capacity and a dual-hand performance task. It was hypothesised that children with DD show alterations related to long-latency ERP components when selecting a response with the affected upper limb, reflecting increased cognitive load in order to generate an adequate response and especially so within the dual-hand task.Methods
Fifteen children with unilateral CP participated in the study. One of the participants was excluded due to major visual impairments. Seven of the remaining participants displayed DD. The other seven children served as a control group. All participants performed two versions of a cue-target paradigm, a single-hand capacity and a dual-hand performance task. The ERP components linked to target presentation were inspected: the mid-latency P2 component and the consecutive long-latency N2b component.Results
In the dual-hand performance task children with DD showed an enhancement in mean amplitude of the long-latency N2b component when selecting a response with their affected hand. No differences were found regarding the amplitude of the mid-latency P2 component. No differences were observed regarding the single-hand capacity task. The control group did not display any differences in ERPs linked to target evaluation processes between both hands.Conclusion
These electrophysiological findings show that DD is associated with increased cognitive load when movements are prepared with the affected hand during a dual-hand performance task. These findings confirm behavioural observations, advance our insights on the neural substrate of DD and have implications for therapy. 相似文献48.
Nicoline BM Voet Gijs Bleijenberg George W Padberg Baziel GM van Engelen Alexander CH Geurts 《BMC neurology》2010,10(1):56
Background
In facioscapulohumeral dystrophy (FSHD) muscle function is impaired and declines over time. Currently there is no effective treatment available to slow down this decline. We have previously reported that loss of muscle strength contributes to chronic fatigue through a decreased level of physical activity, while fatigue and physical inactivity both determine loss of societal participation. To decrease chronic fatigue, two distinctly different therapeutic approaches can be proposed: aerobic exercise training (AET) to improve physical capacity and cognitive behavioural therapy (CBT) to stimulate an active life-style yet avoiding excessive physical strain. The primary aim of the FACTS-2-FSHD (acronym for Fitness And Cognitive behavioural TherapieS/for Fatigue and ACTivitieS in FSHD) trial is to study the effect of AET and CBT on the reduction of chronic fatigue as assessed with the Checklist Individual Strength subscale fatigue (CIS-fatigue) in patients with FSHD. Additionally, possible working mechanisms and the effects on various secondary outcome measures at all levels of the International Classification of Functioning, Disability and Health (ICF) are evaluated.Methods/Design
A multi-centre, assessor-blinded, randomized controlled trial is conducted. A sample of 75 FSHD patients with severe chronic fatigue (CIS-fatigue ≥ 35) will be recruited and randomized to one of three groups: (1) AET + usual care, (2) CBT + usual care or (3) usual care alone, which consists of no therapy at all or occasional (conventional) physical therapy. After an intervention period of 16 weeks and a follow-up of 3 months, the third (control) group will as yet be randomized to either AET or CBT (approximately 7 months after inclusion). Outcomes will be assessed at baseline, immediately post intervention and at 3 and 6 months follow up.Discussion
The FACTS-2-FSHD study is the first theory-based randomized clinical trial which evaluates the effect and the maintenance of effects of AET and CBT on the reduction of chronic fatigue in patients with FSHD. The interventions are based on a theoretical model of chronic fatigue in patients with FSHD. The study will provide a unique set of data with which the relationships between outcome measures at all levels of the ICF could be assessed.Trial registration
Dutch Trial Register, NTR1447.49.
Steed AL Barton ES Tibbetts SA Popkin DL Lutzke ML Rochford R Virgin HW 《Journal of virology》2006,80(1):192-200
Establishment of latent infection and reactivation from latency are critical aspects of herpesvirus infection and pathogenesis. Interfering with either of these steps in the herpesvirus life cycle may offer a novel strategy for controlling herpesvirus infection and associated disease pathogenesis. Prior studies show that mice deficient in gamma interferon (IFN-gamma) or the IFN-gamma receptor have elevated numbers of cells reactivating from murine gammaherpesvirus 68 (gammaHV68) latency, produce infectious virus after the establishment of latency, and develop large-vessel vasculitis. Here, we demonstrate that IFN-gamma is a powerful inhibitor of reactivation of gammaHV68 from latency in tissue culture. In vivo, IFN-gamma controls viral gene expression during latency. Importantly, depletion of IFN-gamma in latently infected mice results in an increased frequency of cells reactivating virus. This demonstrates that IFN-gamma is important for immune surveillance that limits reactivation of gammaHV68 from latency. 相似文献
50.
Objective: To determine relative trends in prevalence for overweight for adults compared with children across high‐income countries (Australia, United Kingdom, and United States), middle‐income countries (Brazil and Russia), and low‐income countries (China and Indonesia). Research Methods and Procedures: Extant nationally representative survey data from 1971 to the present are used. Prevalence of overweight for adults ≥18.0 years of age and children 6.0 to 17.9 years of age were used. Absolute and relative annual rates of change in prevalence of overweight in children and adults were the key outcomes. Results: Absolute rates of increase in overweight were higher among adults than among children in all studied countries except Australia. However, relative rates of increase in overweight indicate faster increases in overweight among children in Brazil, China, and the three high‐income countries. As a result, the relative excess of overweight among adults, seen initially in all countries, increased in Indonesia and Russia, but it decreased in Australia, Brazil, China, United Kingdom, and United States. In Brazil, time trends indicate an acceleration in the annual rate of change in overweight for children and a deceleration for adults, whereas in the United States, the increase in overweight shows acceleration for both children and adults. Discussion: In absolute terms, overweight increased faster among children than adults only in Australia; however, the relative gap between children and adults is closing in four additional countries, Brazil, China, the United Kingdom, and the United States. 相似文献