全文获取类型
收费全文 | 320篇 |
免费 | 9篇 |
专业分类
329篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 11篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 17篇 |
2007年 | 27篇 |
2006年 | 18篇 |
2005年 | 22篇 |
2004年 | 8篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1975年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1960年 | 3篇 |
排序方式: 共有329条查询结果,搜索用时 0 毫秒
61.
Tara D. Wehrly Audrey Chong Kimmo Virtaneva Dan E. Sturdevant Robert Child Jessica A. Edwards Dedeke Brouwer Vinod Nair Elizabeth R. Fischer Luke Wicke Alissa J. Curda John J. Kupko III Craig Martens Deborah D. Crane Catharine M. Bosio Stephen F. Porcella Jean Celli 《Cellular microbiology》2009,11(7):1128-1150
62.
Mia Catharine Mattioli Alexandria B. Boehm Jennifer Davis Angela R. Harris Mwifadhi Mrisho Amy J. Pickering 《PloS one》2014,9(1)
Background
Diarrhea is one of the leading causes of mortality in young children. Diarrheal pathogens are transmitted via the fecal-oral route, and for children the majority of this transmission is thought to occur within the home. However, very few studies have documented enteric pathogens within households of low-income countries.Methods and Findings
The presence of molecular markers for three enteric viruses (enterovirus, adenovirus, and rotavirus), seven Escherichia coli virulence genes (ECVG), and human-specific Bacteroidales was assessed in hand rinses and household stored drinking water in Bagamoyo, Tanzania. Using a matched case-control study design, we examined the relationship between contamination of hands and water with these markers and child diarrhea. We found that the presence of ECVG in household stored water was associated with a significant decrease in the odds of a child within the home having diarrhea (OR = 0.51; 95% confidence interval 0.27–0.93). We also evaluated water management and hygiene behaviors. Recent hand contact with water or food was positively associated with detection of enteric pathogen markers on hands, as was relatively lower volumes of water reportedly used for daily hand washing. Enteropathogen markers in stored drinking water were more likely found among households in which the markers were also detected on hands, as well as in households with unimproved water supply and sanitation infrastructure.Conclusions
The prevalence of enteric pathogen genes and the human-specific Bacteroidales fecal marker in stored water and on hands suggests extensive environmental contamination within homes both with and without reported child diarrhea. Better stored water quality among households with diarrhea indicates caregivers with sick children may be more likely to ensure safe drinking water in the home. Interventions to increase the quantity of water available for hand washing, and to improve food hygiene, may reduce exposure to enteric pathogens in the domestic environment. 相似文献63.
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) and its regulatory partner phospholamban (PLN) are essential for myocardial contractility. Arg(9) → Cys (R9C) and Arg(14) deletion (R14del) mutations in PLN are associated with lethal dilated cardiomyopathy in humans. To better understand these mutations, we made a series of amino acid substitutions in the cytoplasmic domain of PLN and tested their ability to inhibit SERCA. R9C is a complete loss-of-function mutant of PLN, whereas R14del is a mild loss-of-function mutant. When combined with wild-type PLN to simulate heterozygous conditions, the mutants had a dominant negative effect on SERCA function. A series of targeted mutations in this region of the PLN cytoplasmic domain ((8)TRSAIRR(14)) demonstrated the importance of hydrophobic balance in proper PLN regulation of SERCA. We found that Arg(9) → Leu and Thr(8) → Cys substitutions mimicked the behavior of the R9C mutant, and an Arg(14) → Ala substitution mimicked the behavior of the R14del mutant. The results reveal that the change in hydrophobicity resulting from the R9C and R14del mutations is sufficient to explain the loss of function and persistent interaction with SERCA. Hydrophobic imbalance in the cytoplasmic domain of PLN appears to be a predictor for the development and progression of dilated cardiomyopathy. 相似文献
64.
Libo Tan Amanda E. Wray Michael H. Green A. Catharine Ross 《Journal of lipid research》2014,55(6):1077-1086
Vitamin A (VA) metabolism in neonates is virtually uncharacterized. Our objective was to develop a compartmental model of VA metabolism in unsupplemented and VA-supplemented neonatal rats. On postnatal day 4, pups (n = 3/time) received 11,12-[3H]retinol orally, in either oil (control) or VA combined with retinoic acid (VARA) [VA (∼6 mg/kg body weight) + 10% retinoic acid]. Plasma and tissues were collected at 14 time points up to 14 days after dose administration. VARA supplementation rapidly, but transiently, increased total retinol mass in plasma, liver, and lung. It decreased the peak fraction of the dose in plasma. A multi-compartmental model developed to fit plasma [3H]retinol data predicted more extensive recycling of retinol between plasma and tissues in neonates compared with that reported in adults (144 vs. 12–13 times). In VARA pups, the recycling number for retinol between plasma and tissues (100 times) and the time that retinol spent in plasma were both lower compared with controls; VARA also stimulated the uptake of plasma VA into extravascular tissues. A VARA perturbation model indicated that the effect of VARA in stimulating VA uptake into tissues in neonates is both dramatic and transient. 相似文献
65.
66.
On the Development of Ectopic Eyes in DROSOPHILA MELANOGASTER Produced by the Mutation Extra Eye (EE) 下载免费PDF全文
The mutation ee often produces an ectopic eye on the vertex that is a mirror image partial duplication of the normal eye on the ipsilateral side of the head. The pattern of the duplication and a clonal analysis by mitotic recombination indicate that the duplications are of dorsal eye and orbital structures. Large ectopic eyes (more than 100 ommatidia) and their surrounding bristles may be produced without cuticular deficiencies. The penetrance of ee is temperature dependent with penetrance higher (72%) at 25 degrees and 29 degrees than at 19 degrees (43%). Temperature shift experiments show two temperature-sensitive periods: one at midembryogenesis, the other at mid-first larval instar. Microscopic examination of ee late-second and third instar imaginal cephalic discs show no indication of growth of the extra tissue needed to produce the duplication until after mid-third instar. This was confirmed by cell counts of ee and wild-type discs. There is no evidence of differential cell death in the two types of discs at this stage, although much earlier cell death is postulated. Tests for cell autonomy of the mutation by the production of morphogenetic clones suggest nonautonomy. Formation of pattern duplications by mutant genes is discussed in terms of cell death that eliminates whole developmental compartments, restricted cell death that occurs within a compartment, extensive cell death within a compartment and proliferative growth unassociated with cell lethality. 相似文献
67.
68.
Harry K. Kaya Catharine M. Mannion T. M. Burlando C. E. Nelsen 《Journal of nematology》1987,19(3):287-291
The entomogenous nematode Steinernema feltiae was encapsulated in an alginate matrix containing a tomato seed. When these capsules were placed on 0.8% agar for 7 days, the seed germinated and ca. 20% of the nematodes escaped from the capsules, whereas only 0.1% escaped from capsules without seeds. When capsules containing nematodes and a seed were planted into sterilized or nonsterilized soil, nematodes escaped to infect Galleria mellonella larvae. When seed in capsules containing ca. 274 nematodes per capsule were planted in nonsterilized soil, Galleria mortality was 90% 1 week later. Galleria mortality declined to 27%, 23%, and 0% in weeks 2, 4, and 8 postplant, respectively. In sterilized soil, Galleria mortality was 96% and did not differ significantly from the nonsterilized soil in week 1, but was significantly higher in sterilized soil over nonsterilized soil for week 2 (81%) and week 4 (51%). When capsules containing nematodes only were used, Galleria mortality was 71% in sterilized soil 1 week after planting and 58%, 33%, and 12% in weeks 2, 4, and 8 postplant, respectively. In nonsterilized soil, Galleria mortality was 8%, 30%, 21%, and 28% after 1, 2, 4, and 8 weeks, respectively, using only encapsulated nematodes. When the number of nematodes per capsule was increased to ca. 817, Galleria mortality was 92 % or higher in sterilized soil from week 1 to week 4. 相似文献
69.
In the corpora allata (CA) of the viviparous cockroach, Diploptera punctata, a cycle of juvenile hormone (JH) synthesis during ovarian maturation can be correlated with cyclical changes in CA volumes and cell numbers. Uptake of [3H]-thymidine occurs in nuclei of CA cells during periods of increase in cell number. Both members of a pair of CA maintain symmetry of volume, cell number and rate of JH synthesis. After a cycle of CA activity, the CA can be transplanted to a young, allatectomized female, where they support a second wave of oöcyte development. 相似文献
70.