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排序方式: 共有197条查询结果,搜索用时 93 毫秒
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Longhuan Ma Kalyan K. Dewan Dawn L. Taylor-Mulneix Shannon M. Wagner Bodo Linz Israel Rivera Yang Su Amanda D. Caulfield Uriel Blas-Machado Eric T. Harvill 《PLoS pathogens》2021,17(8)
Whooping cough is resurging in the United States despite high vaccine coverage. The rapid rise of Bordetella pertussis isolates lacking pertactin (PRN), a key vaccine antigen, has led to concerns about vaccine-driven evolution. Previous studies showed that pertactin can mediate binding to mammalian cells in vitro and act as an immunomodulatory factor in resisting neutrophil-mediated clearance. To further investigate the role of PRN in vivo, we examined the functions of pertactin in the context of a more naturally low dose inoculation experimental system using C3H/HeJ mice that is more sensitive to effects on colonization, growth and spread within the respiratory tract, as well as an experimental approach to measure shedding and transmission between hosts. A B. bronchiseptica pertactin deletion mutant was found to behave similarly to its wild-type (WT) parental strain in colonization of the nasal cavity, trachea, and lungs of mice. However, the pertactin-deficient strain was shed from the nares of mice in much lower numbers, resulting in a significantly lower rate of transmission between hosts. Histological examination of respiratory epithelia revealed that pertactin-deficient bacteria induced substantially less inflammation and mucus accumulation than the WT strain and in vitro assays verified the effect of PRN on the induction of TNF-α by murine macrophages. Interestingly, only WT B. bronchiseptica could be recovered from the spleen of infected mice and were further observed to be intracellular among isolated splenocytes, indicating that pertactin contributes to systemic dissemination involving intracellular survival. These results suggest that pertactin can mediate interactions with immune cells and augments inflammation that contributes to bacterial shedding and transmission between hosts. Understanding the relative contributions of various factors to inflammation, mucus production, shedding and transmission will guide novel strategies to interfere with the reemergence of pertussis. 相似文献
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Alícia C. Piffer Francine M. dos Santos Marcos P. Thom Camila Diehl Ane Wichine Acosta Garcia Uriel Perin Kinskovski Rafael de Oliveira Schneider Alexandra Gerber Bruno Csar Feltes Augusto Schrank Ana Tereza R. Vasconcelos Guido Lenz Lívia Kmetzsch Marilene H. Vainstein Charley C. Staats 《Genetics and molecular biology》2021,44(3)
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Kathryn L. Schaber Amy C. Morrison William H. Elson Helvio Astete-Vega Jhonny J. Crdova-Lpez Esther Jennifer Ríos Lpez W. Lorena Quiroz Flores Alfonso S. Vizcarra Santillan Thomas W. Scott Lance A. Waller Uriel Kitron Christopher M. Barker T. Alex Perkins Alan L. Rothman Gonzalo M. Vazquez-Prokopec John P. Elder Valerie A. Paz-Soldan 《PLoS neglected tropical diseases》2021,15(7)
BackgroundHuman mobility among residential locations can drive dengue virus (DENV) transmission dynamics. Recently, it was shown that individuals with symptomatic DENV infection exhibit significant changes in their mobility patterns, spending more time at home during illness. This change in mobility is predicted to increase the risk of acquiring infection for those living with or visiting the ill individual. It has yet to be considered, however, whether social contacts are also changing their mobility, either by socially distancing themselves from the infectious individual or increasing contact to help care for them. Social, or physical, distancing and caregiving could have diverse yet important impacts on DENV transmission dynamics; therefore, it is necessary to better understand the nature and frequency of these behaviors including their effect on mobility.Methodology and principal findingsThrough community-based febrile illness surveillance and RT-PCR infection confirmation, 67 DENV positive (DENV+) residents were identified in the city of Iquitos, Peru. Using retrospective interviews, data were collected on visitors and home-based care received during the illness. While 15% of participants lost visitors during their illness, 22% gained visitors; overall, 32% of all individuals (particularly females) received visitors while symptomatic. Caregiving was common (90%), particularly caring by housemates (91%) and caring for children (98%). Twenty-eight percent of caregivers changed their behavior enough to have their work (and, likely, mobility patterns) affected. This was significantly more likely when caring for individuals with low “health-related quality of well-being” during illness (Fisher’s Exact, p = 0.01).Conclusions/SignificanceOur study demonstrates that social contacts of individuals with dengue modify their patterns of visitation and caregiving. The observed mobility changes could impact a susceptible individual’s exposure to virus or a presymptomatic/clinically inapparent individual’s contribution to onward transmission. Accounting for changes in social contact mobility is imperative in order to get a more accurate understanding of DENV transmission. 相似文献
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Chaves Luis F Harrington Laura C Keogh Carolyn L Nguyen Andy M Kitron Uriel D 《Frontiers in zoology》2010,7(1):1-11
Background
During the non-breeding period, many birds migrate to milder areas, found closer to the equator than their breeding sites. Opposite movements are very rare. In the Southern Ocean, the abundance of 13C declines markedly with more southern latitude, providing a characteristic 13C isoscape. This can be used as a tracer for the movement of seabirds between breeding and inter-breeding areas, by comparing stable isotope ratios of feathers grown at different times of the year.Results
We studied seasonal movements of Thin-billed prions (Aves, Procellariiformes), breeding at the Subantarctic Falkland/Malvinas Islands, compared with those of Wilson's storm-petrels breeding in the Antarctic South Shetland Islands. The two species showed opposite migratory movements. While Wilson's storm-petrels moved to warmer waters north of the Drake Passage in winter, Thin-billed prions showed a reversed movement towards more polar waters. Carbon stable isotope ratios in recent and historical feathers indicated that poleward winter movements of Thin-billed prions were less common historically (45% in 1913-1915), and have only recently become dominant (92% in 2003-2005), apparently in response to warming sea temperatures.Conclusions
This study shows that pelagic seabirds can rapidly change migration strategies within populations, including migration towards more poleward waters in winter. 相似文献77.
Aurelio Ramírez‐Bautista Jack W. Sites Jonathon C. Marshall Raciel Cruz‐Elizalde Csar A. Díaz‐Marín Uriel Hernndez‐Salinas Christian Berriozabal‐Islas Aaron García‐Rosales 《Acta zoologica》2021,102(1):63-76
In this study, sexual dimorphism, reproductive cycles, litter size and offspring size of a population of the little‐known species Sceloporus palaciosi in central Mexico were analysed. Significant male‐biased sexual size dimorphism was recorded in snout–vent length (SVL), head length, head width, forearm length and tibia length. Both sexes showed asynchronous reproductive cycles, and males reached sexual maturity at a smaller SVL (33 mm) than females (37 mm). Testes volumes were small from January to February, testicular recrudescence began from March to June, and decreased in July, but increased again in August and September, followed by a second decrease from October to December. In females, vitellogenesis began from May until ovulation in December. Embryonic development extended from November to March, and a small number of females carried embryos through July. Mean litter size was 4.0 and was positively correlated with female SVL. The length of the reproductive period in S. palaciosi recorded in this study is longer than that recorded for other populations in other parts of this species range. Further studies are needed to clarify reproductive cycles in the other isolated populations of S. palaciosi, and then extended to other species and chromosome races in the Sceloporus grammicus complex. 相似文献
78.
Tova Neufeld Barbara Ludwig Uriel Barkai Gordon C. Weir Clark K. Colton Yoav Evron Maria Balyura Karina Yavriyants Baruch Zimermann Dmitri Azarov Shiri Maimon Noa Shabtay Tania Rozenshtein Dana Lorber Anja Steffen Udi Willenz Konstantine Bloch Pnina Vardi Ran Taube Paul de Vos Eli C. Lewis Stefan R. Bornstein Avi Rotem 《PloS one》2013,8(8)
Developing a device that protects xenogeneic islets to allow treatment and potentially cure of diabetes in large mammals has been a major challenge in the past decade. Using xenogeneic islets for transplantation is required in light of donor shortage and the large number of diabetic patients that qualify for islet transplantation. Until now, however, host immunoreactivity against the xenogeneic graft has been a major drawback for the use of porcine islets. Our study demonstrates the applicability of a novel immunoprotective membrane that allows successful xenotransplantation of rat islets in diabetic minipigs without immunosuppressive therapy. Rat pancreatic islets were encapsulated in highly purified alginate and integrated into a plastic macrochamber covered by a poly-membrane for subcutaneous transplantation. Diabetic Sinclair pigs were transplanted and followed for up to 90 days. We demonstrated a persistent graft function and restoration of normoglycemia without the need for immunosuppressive therapy. This concept could potentially offer an attractive strategy for a more widespread islet replacement therapy that would restore endogenous insulin secretion in diabetic patients without the need for immunosuppressive drugs and may even open up an avenue for safe utilization of xenogeneic islet donors. 相似文献
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