全文获取类型
收费全文 | 1306篇 |
免费 | 95篇 |
出版年
2023年 | 12篇 |
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 23篇 |
2019年 | 31篇 |
2018年 | 26篇 |
2017年 | 31篇 |
2016年 | 37篇 |
2015年 | 62篇 |
2014年 | 75篇 |
2013年 | 73篇 |
2012年 | 92篇 |
2011年 | 97篇 |
2010年 | 77篇 |
2009年 | 61篇 |
2008年 | 78篇 |
2007年 | 67篇 |
2006年 | 63篇 |
2005年 | 59篇 |
2004年 | 67篇 |
2003年 | 51篇 |
2002年 | 41篇 |
2001年 | 20篇 |
2000年 | 22篇 |
1999年 | 14篇 |
1998年 | 16篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1970年 | 3篇 |
排序方式: 共有1401条查询结果,搜索用时 15 毫秒
181.
182.
NP Nguyen A Chi M Betz F Almeida P Vos R Davis B Slane M Ceizyk D Abraham L Smith-Raymond M Stevie S Jang S Gelumbauskas V Vinh-Hung 《PloS one》2012,7(8):e42729
Purpose
The study aims to assess the feasibility of intensity-modulated and image-guided radiotherapy (IMRT, and IGRT, respectively) for functional preservation in locally advanced laryngeal cancer. A retrospective review of 27 patients undergoing concurrent chemoradiation for locally advanced laryngeal cancers (8 IMRT, 19 IGRT) was undertaken. In addition to regular clinical examinations, all patients had PET imaging at 4 months and 10 months after radiotherapy, then yearly. Loco-regional control, speech quality and feeding-tube dependency were assessed during follow-up visits.Results
At a median follow-up of 20 months (range 6–57 months), four out of 27 patients (14.8%) developed local recurrence and underwent salvage total laryngectomy. One patient developed distant metastases following salvage surgery. Among the 23 patients who conserved their larynx with no sign of recurrence at last follow-up, 22 (95%) reported normal or near normal voice quality, allowing them to communicate adequately. Four patients (14.8%) had long-term tube feeding-dependency because of severe dysphagia (2 patients) and chronic aspiration (2 patients, with ensuing death from aspiration pneumonia in one patient).Conclusions and Clinical Relevance
Functional laryngeal preservation is feasible with IMRT and IGRT for locally advanced laryngeal cancer. However, dysphagia and aspiration remain serious complications, due most likely to high radiation dose delivery to the pharyngeal musculatures. 相似文献183.
B Gautami D Foncéka MK Pandey MC Moretzsohn V Sujay H Qin Y Hong I Faye X Chen A BhanuPrakash TM Shah MV Gowda SN Nigam X Liang DA Hoisington B Guo DJ Bertioli JF Rami RK Varshney 《PloS one》2012,7(7):e41213
Only a few genetic maps based on recombinant inbred line (RIL) and backcross (BC) populations have been developed for tetraploid groundnut. The marker density, however, is not very satisfactory especially in the context of large genome size (2800 Mb/1C) and 20 linkage groups (LGs). Therefore, using marker segregation data for 10 RILs and one BC population from the international groundnut community, with the help of common markers across different populations, a reference consensus genetic map has been developed. This map is comprised of 897 marker loci including 895 simple sequence repeat (SSR) and 2 cleaved amplified polymorphic sequence (CAPS) loci distributed on 20 LGs (a01-a10 and b01-b10) spanning a map distance of 3, 863.6 cM with an average map density of 4.4 cM. The highest numbers of markers (70) were integrated on a01 and the least number of markers (21) on b09. The marker density, however, was lowest (6.4 cM) on a08 and highest (2.5 cM) on a01. The reference consensus map has been divided into 20 cM long 203 BINs. These BINs carry 1 (a10_02, a10_08 and a10_09) to 20 (a10_04) loci with an average of 4 marker loci per BIN. Although the polymorphism information content (PIC) value was available for 526 markers in 190 BINs, 36 and 111 BINs have at least one marker with >0.70 and >0.50 PIC values, respectively. This information will be useful for selecting highly informative and uniformly distributed markers for developing new genetic maps, background selection and diversity analysis. Most importantly, this reference consensus map will serve as a reliable reference for aligning new genetic and physical maps, performing QTL analysis in a multi-populations design, evaluating the genetic background effect on QTL expression, and serving other genetic and molecular breeding activities in groundnut. 相似文献
184.
Duerr AE Miller TA Lanzone M Brandes D Cooper J O'Malley K Maisonneuve C Tremblay J Katzner T 《PloS one》2012,7(4):e35548
To maximize fitness, flying animals should maximize flight speed while minimizing energetic expenditure. Soaring speeds of large-bodied birds are determined by flight routes and tradeoffs between minimizing time and energetic costs. Large raptors migrating in eastern North America predominantly glide between thermals that provide lift or soar along slopes or ridgelines using orographic lift (slope soaring). It is usually assumed that slope soaring is faster than thermal gliding because forward progress is constant compared to interrupted progress when birds pause to regain altitude in thermals. We tested this slope-soaring hypothesis using high-frequency GPS-GSM telemetry devices to track golden eagles during northbound migration. In contrast to expectations, flight speed was slower when slope soaring and eagles also were diverted from their migratory path, incurring possible energetic costs and reducing speed of progress towards a migratory endpoint. When gliding between thermals, eagles stayed on track and fast gliding speeds compensated for lack of progress during thermal soaring. When thermals were not available, eagles minimized migration time, not energy, by choosing energetically expensive slope soaring instead of waiting for thermals to develop. Sites suited to slope soaring include ridges preferred for wind-energy generation, thus avian risk of collision with wind turbines is associated with evolutionary trade-offs required to maximize fitness of time-minimizing migratory raptors. 相似文献
185.
B Dave MD Landis LE Dobrolecki MF Wu X Zhang TF Westbrook SG Hilsenbeck D Liu MT Lewis DJ Tweardy JC Chang 《PloS one》2012,7(8):e30207
Metastasis and disease relapse are hypothesized to result from tumor initiating cells (TICs). Previously, we have defined a CD44+/CD24-/low mammosphere-forming tumorigenic 493-gene signature in breast cancer. Stat3 was identified as a critical node in self-renewal based on an ongoing lentiviral shRNA screen being conducted in two breast cancer cell lines SUM159 and BT549. In corroborating work, targeting the SH2 domain of Stat3 with a novel small molecule decreased the percentage of cells expressing TIC markers (CD44+/CD24-/low and ALDH+) and mammosphere formation in p-Stat3 overexpressing human breast cancer xenografts in SCID-beige mice. Importantly, we observed a four-fold improvement in the 30-day recurrence-free survival relative to docetaxel alone with the addition of the Stat3 inhibitor in the chemoresistant tumor model. Thus, these findings provide a strong impetus for the development of selective Stat3 inhibitors in order to improve survival in patients with p-Stat3 overexpressing tumors. 相似文献
186.
Sameer Mirza Bryan J. Katafiasz Rakesh Kumar Jun Wang Shakur Mohibi Smrati Jain Channabasavaiah Basavaraju Gurumurthy Tej K. Pandita Bhavana J. Dave Hamid Band Vimla Band 《Cell cycle (Georgetown, Tex.)》2012,11(22):4266-4274
Cell cycle regulation and DNA repair following damage are essential for maintaining genome integrity. DNA damage activates checkpoints in order to repair damaged DNA prior to exit to the next phase of cell cycle. Recently, we have shown the role of Ada3, a component of various histone acetyltransferase complexes, in cell cycle regulation, and loss of Ada3 results in mouse embryonic lethality. Here, we used adenovirus-Cre-mediated Ada3 deletion in Ada3fl/fl mouse embryonic fibroblasts (MEFs) to assess the role of Ada3 in DNA damage response following exposure to ionizing radiation (IR). We report that Ada3 depletion was associated with increased levels of phospho-ATM (pATM), γH2AX, phospho-53BP1 (p53BP1) and phospho-RAD51 (pRAD51) in untreated cells; however, radiation response was intact in Ada3−/− cells. Notably, Ada3−/− cells exhibited a significant delay in disappearance of DNA damage foci for several critical proteins involved in the DNA repair process. Significantly, loss of Ada3 led to enhanced chromosomal aberrations, such as chromosome breaks, fragments, deletions and translocations, which further increased upon DNA damage. Notably, the total numbers of aberrations were more clearly observed in S-phase, as compared with G₁ or G₂ phases of cell cycle with IR. Lastly, comparison of DNA damage in Ada3fl/fl and Ada3−/− cells confirmed higher residual DNA damage in Ada3−/− cells, underscoring a critical role of Ada3 in the DNA repair process. Taken together, these findings provide evidence for a novel role for Ada3 in maintenance of the DNA repair process and genomic stability. 相似文献
187.
First detection of Nosema ceranae, a microsporidian parasite of European honey bees (Apis mellifera), in Canada and central USA 总被引:1,自引:0,他引:1
Williams GR Shafer AB Rogers RE Shutler D Stewart DT 《Journal of invertebrate pathology》2008,97(2):189-192
Nosema ceranae is an emerging microsporidian parasite of European honey bees, Apis mellifera, but its distribution is not well known. Six Nosema-positive samples (determined from light microscopy of spores) of adult worker bees from Canada (two each from Nova Scotia, New Brunswick, and Prince Edward Island) and two from USA (Minnesota) were tested to determine Nosema species using previously-developed PCR primers of the 16S rRNA gene. We detected for the first time N. ceranae in Canada and central USA. One haplotype of N. ceranae was identified; its virulence may differ from that of other haplotypes. 相似文献
188.
Western honey bee (Apis mellifera) colonies in Nova Scotia, Canada were sampled in spring and late summer 2007 to evaluate efficacy of fumagillin dicyclohexylammonium (hereafter, fumagillin) against Nosema ceranae. Colonies treated with fumagillin in September 2006 (n = 94) had significantly lower Nosema intensity in spring 2007 than did colonies that received no treatment (n = 51), but by late summer 2007 no difference existed between groups. Molecular sequencing of 15 infected colonies identified N. ceranae in 93.3% of cases, suggesting that fumagillin is successful at temporarily reducing this recent invasive parasite in western honey bees. 相似文献
189.
Tilburgs T Roelen DL van der Mast BJ de Groot-Swings GM Kleijburg C Scherjon SA Claas FH 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(8):5737-5745
During pregnancy, the maternal immune system has to tolerate the persistence of fetal alloantigens. Many mechanisms contribute to the prevention of a destructive immune response mediated by maternal alloreactive lymphocytes directed against the allogeneic fetus. Murine studies suggest that CD4(+)CD25(+) T cells provide mechanisms of specific immune tolerance to fetal alloantigens during pregnancy. Previous studies by our group demonstrate that a significantly higher percentage of activated T cells and CD4(+)CD25(bright) T cells are present in decidual tissue in comparison with maternal peripheral blood in human pregnancy. In this study, we examined the phenotypic and functional properties of CD4(+)CD25(bright) T cells derived from maternal peripheral blood and decidual tissue. Depletion of CD4(+)CD25(bright) T cells from maternal peripheral blood demonstrates regulation to third party umbilical cord blood cells comparable to nonpregnant controls, whereas the suppressive capacity to umbilical cord blood cells of her own child is absent. Furthermore, maternal peripheral blood shows a reduced percentage of CD4(+)CD25(bright)FOXP3(+) and CD4(+)CD25(bright)HLA-DR(+) cells compared with peripheral blood of nonpregnant controls. In contrast, decidual lymphocyte isolates contain high percentages of CD4(+)CD25(bright) T cells with a regulatory phenotype that is able to down-regulate fetus-specific and fetus-nonspecific immune responses. These data suggest a preferential recruitment of fetus-specific regulatory T cells from maternal peripheral blood to the fetal-maternal interface, where they may contribute to the local regulation of fetus-specific responses. 相似文献
190.