全文获取类型
收费全文 | 456篇 |
免费 | 35篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 37篇 |
2012年 | 41篇 |
2011年 | 34篇 |
2010年 | 19篇 |
2009年 | 12篇 |
2008年 | 21篇 |
2007年 | 10篇 |
2006年 | 18篇 |
2005年 | 28篇 |
2004年 | 17篇 |
2003年 | 22篇 |
2002年 | 18篇 |
2001年 | 3篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1988年 | 2篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1948年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有491条查询结果,搜索用时 15 毫秒
1.
Susannah Louise Varmuza 《Development genes and evolution》1992,201(3):142-148
Summary LTXBO mice develop ovarian teratomas at high frequency. The phenotype of tumour tissues is unusual in that most contain trophoblast elements. Since the tumours are derived from parthenogenetically activated oocytes, they would not be expected to produce trophoblast. The developmental potential of parthenogenetic cells from these mice was tested in aggregation chimeras. No contribution to trophoblast tissues was observed. However, a high incidence of morphological abnormalities was seen, suggesting that the parthenogenetic cells exerted a teratogenic effect. 相似文献
2.
3.
A Familial Factor Independent of CAG Repeat Length Influences Age at Onset of Machado-Joseph Disease 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《American journal of human genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Anita L. DeStefano L. Adrienne Cupples Patricia Maciel Claudia Gaspar Joao Radvany David M. Dawson Lewis Sudarsky Lee Corwin Paula Coutinho Patrick MacLeod Jorge Sequeiros Guy A. Rouleau Lindsay A. Farrer 《American journal of human genetics》1996,59(1):119-127
Machado-Joseph disease (MJD) is a late-onset, progressive, neurodegenerative disorder caused by the expansion of an unstable trinucleotide (CAG) repeat sequence in a novel gene (MJD1) on chromosome 14. Previous studies showed that age at onset is negatively correlated with the number of CAG repeat units, but only part of the variation in onset age is explained by CAG repeat length. Ages at onset and CAG repeat lengths of 136 MJD patients from 23 kindreds of Portuguese descent were analyzed, to determine whether familial factors independent of CAG repeat length modulate age at onset of MJD. Correlation among sibs for onset age adjusted for CAG repeat length was .43, which indicates that an environmental or genetic factor common to sibs influences onset age. Positive correlations were also observed for avuncular (r = .22) and first-cousin pairs (r = .28), which supports the hypothesis that a genetic factor is influencing age at onset. Commingling analysis of onset ages adjusted for CAG repeat length identified three distributions in this population of affected individuals. Further studies of a much larger sample are needed to determine whether these distributions represent the influence of a genetic or environmental factor. 相似文献
4.
A full-length zebrafish cDNA clone and a partial mouse cDNA clone similar to chick DM-GRASPwere isolated and analyzed. The nucleotide sequence of the full-length zebrafish clone shares 54% identity, and predicts 39% amino acid identity, with chick DM-GRASP. The partial mouse clone shares 76% nucleotide identity, and predicts 76% amino acid identity, with chick DM-GRASP. The predicted proteins encoded by both of these clones exhibit conserved structural domains that are characteristic of the chick protein. These features may identify them as a distinct subfamily within the immunoglobulin superfamily of cell adhesion molecules. Express of the zebrafish DM-GRASP protein is similar to chick DM-GRASP and is principally restricted to a small subset of developing sensory and motor neurons during axonogenesis. Zebrafish DM-GRASP expression was temporally regulated and limited to specific axon domains. This regional expression correlated with fasciculated axon domains. These results suggest that the zebrafish and mouse cDNA clones represent the respective fish and mammalian homologs of thick DM-GRASP. The highly selective expression of zebrafish DM-GRASP suggests that it is involved in the selective fasciculation and guidance of axons along their normal pathways. 1994 John Wiley & Sons, Inc. 相似文献
5.
Michael Garrick Donna Scott Susannah Walpole Eric Finkelstein Joy Whitbred Sandeep Chopra Lalitha Trivikram David Mayes Daphne Rhodes Kimberly Cabbagestalk Rahmi Oklu Adnan Sadiq Brett Mascia James Hoke Laura Garrick 《Biometals》1997,10(2):65-76
Belgrade rats inherit microcytic, hypochromic anemia as an autosomalrecessive trait (gene symbol b). Erythrocytes and tissue are iron deficientin the face of elevated TIBC (total iron binding capacity) and percent ironsaturation; iron injections increased the number of erythrocytes but theirappearance remained abnormal. We have investigated iron supplements toimprove husbandry of b/b rats and to learn more about the underlying defectand its tissue distribution. Weekly IM (intramuscular) injections ofiron–dextran (Imferon at 30 mg kg) improved the anemia but did not alter thered cell morphology. Certain diets also improved the health of b/b rats whencompared to standard rat chows by the criteria of weight, survival toadulthood, hematology and reproduction. The critical nutritional factorturned out to be iron bioavailability, with ferrous iron added to the dietimproving the health of Belgrade rats without affecting the underlyingerythroid defect. Tissue iron measurements after dietary or parenteralsupplementation confirmed the iron deficient status of untreated b/b rats andestablished that dietary ferrous iron partially relieved this deficiency,with injections leading to greater amounts of tissue iron. Serum iron andTIBC were also found to be elevated in untreated b/b rats, with dietarysupplementation decreasing but not eliminating the elevation in TIBC. Thesestudies indicate that iron supplements can improve the health of b/b ratswithout altering the underlying defect and also suggest that the mutationcould alter iron uptake in the GI (gastrointestinal) tract. 相似文献
6.
An adult from a research colony and a litter of 5-week-old Mongolian gerbils (Meriones unguiculatus) from a pet store were found to have pinworms identified as Syphacia obvelata. The infected gerbils were allowed to cohabitate with uninfected gerbils. Similarly, infected gerbils were caged with uninfected mice and infected mice with uninfected gerbils. Results of these studies showed that Syphacia obvelata can be transmitted from gerbil to gerbil, gerbil to mouse, and mouse to gerbil. 相似文献
7.
Margaret M. Grant Anne S. Brown Lawrence M. Corwin Robert F. Troxler Carl Franzblau 《Biochimica et Biophysica Acta (BBA)/General Subjects》1975,404(2)
The effects of L-azetidine 2-carboxylic acid on growth and proline metabolism in a proline-requiring auxotroph of Escherichia coli are described. The homologue inhibited growth of the wild type and it, alone, did not substitute effectively for proline as a growth supplement for the mutant. In medium containing 0.05 mM proline, the addition of increasing amounts of homologue progressively inhibited growth of the wild type but stimulated growth of the mutant at homologue: proline ratios of 10 : 1 and 50 : 1. This suggested that the homologue exerted a “sparing effect” on proline in the mutant.The incorporation of L-[U-14C]proline and L-[3H]azetidine 2-carboxylic acid into hot trichloroacetic acid-insoluble material in the mutant was measured. Amino acid analysis of the insoluble material from cells incubated with radiolabeled proline alone revealed that proline was partially degraded and metabolized to other amino acids prior to incorporation into protein. The addition of unlabeled homologue to the incubation medium significantly reduced proline catabolism, suggesting that the homologue exerted a sparing effect on proline in this mutant. In medium containing unlabeled proline and radiolabeled L-azetidine 2-carboxylic acid, the homologuewas incorporated both intact and partially degraded prior to incorporation into protein. Alanine was the major L-azetidine 2-carboxylic acid catabolite. 相似文献
8.
9.
Philip Cooper Alan W. Walker Jorge Reyes Martha Chico Susannah J. Salter Maritza Vaca Julian Parkhill 《PloS one》2013,8(10)
Background
The soil-transmitted helminth (STH), Trichuris trichiura colonises the human large intestine where it may modify inflammatory responses, an effect possibly mediated through alterations in the intestinal microbiota. We hypothesised that patent T. trichiura infections would be associated with altered faecal microbiota and that anthelmintic treatment would induce a microbiota resembling more closely that observed in uninfected individuals.Materials and Methods
School children in Ecuador were screened for STH infections and allocated to 3 groups: uninfected, T. trichiura only, and mixed infections with T. trichiura and Ascaris lumbricoides. A sample of uninfected children and those with T. trichiura infections only were given anthelmintic treatment. Bacterial community profiles in faecal samples were studied by 454 pyrosequencing of 16 S rRNA genes.Results
Microbiota analyses of faeces were done for 97 children: 30 were uninfected, 17 were infected with T. trichiura, and 50 with T. trichiura and A. lumbricoides. Post-treatment samples were analyzed for 14 children initially infected with T. trichiura alone and for 21 uninfected children. Treatment resulted in 100% cure of STH infections. Comparisons of the microbiota at different taxonomic levels showed no statistically significant differences in composition between uninfected children and those with T. trichiura infections. We observed a decreased proportional abundance of a few bacterial genera from the Clostridia class of Firmicutes and a reduced bacterial diversity among children with mixed infections compared to the other two groups, indicating a possible specific effect of A. lumbricoides infection. Anthelmintic treatment of children with T. trichiura did not alter faecal microbiota composition.Discussion
Our data indicate that patent human infections with T. trichiura may have no effect on faecal microbiota but that A. lumbricoides colonisation might be associated with a disturbed microbiota. Our results also catalogue the microbiota of rural Ecuadorians and indicate differences with individuals from more urban industrialised societies. 相似文献10.
David Corwin Clay Holdsworth Russell C. Rockne Andrew D. Trister Maciej M. Mrugala Jason K. Rockhill Robert D. Stewart Mark Phillips Kristin R. Swanson 《PloS one》2013,8(11)