全文获取类型
收费全文 | 398篇 |
免费 | 47篇 |
专业分类
445篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 16篇 |
2015年 | 20篇 |
2014年 | 20篇 |
2013年 | 22篇 |
2012年 | 31篇 |
2011年 | 18篇 |
2010年 | 14篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1972年 | 5篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有445条查询结果,搜索用时 0 毫秒
71.
72.
73.
The high cost of inpatient hospitalization and the rise in the number of private psychiatric beds for children and adolescents prompt several questions about who is using these services. To examine these issues, a review focusing on the use of psychiatric inpatient services by children was undertaken. The history of inpatient care of children is briefly outlined, recent public policies contributing to the rise in the number of psychiatric beds are considered, and findings from available studies are reviewed. We conclude that the data base is inadequate to draw many conclusions about who is using child psychiatric inpatient services. There appear, however, to be important differences in use of inpatient services according to age and perhaps by institutional type and geographic region. Suggestions for future research and some of the social policy implications are discussed as well. 相似文献
74.
75.
76.
77.
R. J. Smialowicz C. M. Weil P. Marsh M. M. Riddle R. R. Rogers B. F. Rehnberg 《Bioelectromagnetics》1981,2(3):279-284
Rats (N = 16) exposed individually in circularly polarized waveguides to 970-MHz electromagnetic radiation (SAR=2.5 mW/g, 22 h daily for 70 consecutive days) had significantly higher serum levels of triglycerides, albumin, and total protein compared with sham-irradiated controls. No difference was observed in the weights, hematologic profile, or in vitro lymphocyte responses to mitogens between these two groups. The higher serum levels of triglycerides in radiofrequency-radiation-exposed rats suggest a non-specific stress reaction. 相似文献
78.
Kaitlyn?R.?Ammann Katrina?J.?DeCook Phat?L.?Tran Valerie?M.?Merkle Pak?K.?Wong Marvin?J.?SlepianEmail author 《Journal of biological engineering》2015,9(1):19
Background
Cell migration is a vital process for growth and repair. In vitro migration assays, utilized to study cell migration, often rely on physical scraping of a cell monolayer to induce cell migration. The physical act of scrape injury results in numerous factors stimulating cell migration – some injury-related, some solely due to gap creation and loss of contact inhibition. Eliminating the effects of cell injury would be useful to examine the relative contribution of injury versus other mechanisms to cell migration. Cell exclusion assays can tease out the effects of injury and have become a new avenue for migration studies. Here, we developed two simple non-injury techniques for cell exclusion: 1) a Pyrex® cylinder - for outward migration of cells and 2) a polydimethylsiloxane (PDMS) insert - for inward migration of cells. Utilizing these assays smooth muscle cells (SMCs) and human umbilical vein endothelial cells (HUVECs) migratory behavior was studied on both polystyrene and gelatin-coated surfaces.Results
Differences in migratory behavior could be detected for both smooth muscle cells (SMCs) and endothelial cells (ECs) when utilizing injury versus non-injury assays. SMCs migrated faster than HUVECs when stimulated by injury in the scrape wound assay, with rates of 1.26 % per hour and 1.59 % per hour on polystyrene and gelatin surfaces, respectively. The fastest overall migration took place with HUVECs on a gelatin-coated surface, with the in-growth assay, at a rate of 2.05 % per hour. The slowest migration occurred with the same conditions but on a polystyrene surface at a rate of 0.33 % per hour.Conclusion
For SMCs, injury is a dominating factor in migration when compared to the two cell exclusion assays, regardless of the surface tested: polystyrene or gelatin. In contrast, the migrating surface, namely gelatin, was a dominating factor for HUVEC migration, providing an increase in cell migration over the polystyrene surface. Overall, the cell exclusion assays - the in-growth and out-growth assays, provide a means to determine pure migratory behavior of cells in comparison to migration confounded by cell wounding and injury.79.
Christina A. Markunas Karen Soldano Kaitlyn Dunlap Heidi Cope Edgar Asiimwe Jeffrey Stajich David Enterline Gerald Grant Herbert Fuchs Simon G. Gregory Allison E. Ashley-Koch 《PloS one》2013,8(4)
Chiari Type I Malformation (CMI) is characterized by displacement of the cerebellar tonsils below the base of the skull, resulting in significant neurologic morbidity. Although multiple lines of evidence support a genetic contribution to disease, no genes have been identified. We therefore conducted the largest whole genome linkage screen to date using 367 individuals from 66 families with at least two individuals presenting with nonsyndromic CMI with or without syringomyelia. Initial findings across all 66 families showed minimal evidence for linkage due to suspected genetic heterogeneity. In order to improve power to localize susceptibility genes, stratified linkage analyses were performed using clinical criteria to differentiate families based on etiologic factors. Families were stratified on the presence or absence of clinical features associated with connective tissue disorders (CTDs) since CMI and CTDs frequently co-occur and it has been proposed that CMI patients with CTDs represent a distinct class of patients with a different underlying disease mechanism. Stratified linkage analyses resulted in a marked increase in evidence of linkage to multiple genomic regions consistent with reduced genetic heterogeneity. Of particular interest were two regions (Chr8, Max LOD = 3.04; Chr12, Max LOD = 2.09) identified within the subset of “CTD-negative” families, both of which harbor growth differentiation factors (GDF6, GDF3) implicated in the development of Klippel-Feil syndrome (KFS). Interestingly, roughly 3–5% of CMI patients are diagnosed with KFS. In order to investigate the possibility that CMI and KFS are allelic, GDF3 and GDF6 were sequenced leading to the identification of a previously known KFS missense mutation and potential regulatory variants in GDF6. This study has demonstrated the value of reducing genetic heterogeneity by clinical stratification implicating several convincing biological candidates and further supporting the hypothesis that multiple, distinct mechanisms are responsible for CMI. 相似文献
80.
Desiree Hunt Floyd Ying Zhang Bijan K. Dey Benjamin Kefas Hannah Breit Kaitlyn Marks Anindya Dutta Christel Herold-Mende Michael Synowitz Rainer Glass Roger Abounader Benjamin W. Purow 《PloS one》2014,9(5)
Glioblastoma is the most common and lethal primary brain tumor. Tumor initiation and recurrence are likely caused by a sub-population of glioblastoma stem cells, which may derive from mutated neural stem and precursor cells. Since CD133 is a stem cell marker for both normal brain and glioblastoma, and to better understand glioblastoma formation and recurrence, we looked for dys-regulated microRNAs in human CD133+ glioblastoma stem cells as opposed to CD133+ neural stem cells isolated from normal human brain. Using FACS sorting of low-passage cell samples followed by microRNA microarray analysis, we found 43 microRNAs that were dys-regulated in common in three separate CD133+ human glioblastomas compared to CD133+ normal neural stem cells. Among these were several microRNAs not previously associated with cancer. We then verified the microRNAs dys-regulated in glioblastoma using quantitative real time PCR and Taqman analysis of the original samples, as well as human GBM stem cell and established cell lines and many human specimens. We show that two candidate oncogenic microRNAs, miR-363 and miR-582-5p, can positively influence glioblastoma survival, as shown by forced expression of the microRNAs and their inhibitors followed by cell number assay, Caspase 3/7 assay, Annexin V apoptosis/fluorescence activated cell sorting, siRNA rescue of microRNA inhibitor treatment, as well as 3′UTR mutagenesis to show luciferase reporter rescue of the most successful targets. miR-582-5p and miR-363 are shown to directly target Caspase 3, Caspase 9, and Bim. 相似文献