全文获取类型
收费全文 | 690篇 |
免费 | 60篇 |
国内免费 | 1篇 |
专业分类
751篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 23篇 |
2015年 | 32篇 |
2014年 | 40篇 |
2013年 | 55篇 |
2012年 | 65篇 |
2011年 | 53篇 |
2010年 | 32篇 |
2009年 | 24篇 |
2008年 | 54篇 |
2007年 | 40篇 |
2006年 | 43篇 |
2005年 | 35篇 |
2004年 | 34篇 |
2003年 | 33篇 |
2002年 | 27篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 1篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1961年 | 1篇 |
1955年 | 1篇 |
1944年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有751条查询结果,搜索用时 15 毫秒
1.
2.
Lily Khadempour Valerie LeMay David Jack J?rg Bohlmann Colette Breuil 《Microbial ecology》2012,64(4):909-917
The mountain pine beetle (MPB) is a native bark beetle of western North America that attacks pine tree species, particularly lodgepole pine. It is closely associated with the ophiostomatoid ascomycetes Grosmannia clavigera, Leptographium longiclavatum, Ophiostoma montium, and Ceratocystiopsis sp.1, with which it is symbiotically associated. To develop a better understanding of interactions between beetles, fungi, and host trees, we used target-specific DNA primers with qPCR to assess the changes in fungal associate abundance over the stages of the MPB life cycle that occur in galleries under the bark of pine trees. Multivariate analysis of covariance identified statistically significant changes in the relative abundance of the fungi over the life cycle of the MPB. Univariate analysis of covariance identified a statistically significant increase in the abundance of Ceratocystiopsis sp.1 through the beetle life cycle, and pair-wise analysis showed that this increase occurs after the larval stage. In contrast, the abundance of O. montium and Leptographium species (G. clavigera, L. longiclavatum) did not change significantly through the MPB life cycle. From these results, the only fungus showing a significant increase in relative abundance has not been formally described and has been largely ignored by other MPB studies. Although our results were from only one site, in previous studies we have shown that the fungi described were all present in at least ten sites in British Columbia. We suggest that the role of Ceratocystiopsis sp.1 in the MPB system should be explored, particularly its potential as a source of nutrients for teneral adults. 相似文献
3.
4.
A rapid fluorometric DNA assay for the measurement of cell density and proliferation in vitro 总被引:4,自引:0,他引:4
Timothy A. McCaffrey Lily A. Agarwal Babette B. Weksler 《In vitro cellular & developmental biology. Plant》1988,24(3):247-252
Summary Many research efforts require the accurate determination of cell density in vitro. However, physical cell counting is inaccurate,
time-intensive and requires removal of the cells from their growth environment, thereby introducing a host of potential artifacts.
The current studies document a very simple method of determining cell density in microtiter wells via DNA-enhanced fluorescence.
Fixed cells are stained with the A-T intercalating DNA stains DAPI or Hoechst 33342 and then fluorescence is quantified in
a plate fluorometer. Fluorescence is shown to be linearly related to cell density as determined by two physical counting methods.
The validity of the method is established in determining serum-stimulated growth of smooth muscle cells and in mitogen-induced
growth of endothelial cells. The fixed cells can be stored for prolonged periods, thus allowing time-course proliferation
assays without interassay variations. The fixed cells are also suitable for determinations of antigens of interest by ELISA.
This method is potentially valuable in many in vitro systems where the quantification of cell density and proliferation is
necessary.
This work supported in part by NIH Cardiovascular Training Grant HL07423 and a grant from the American Federation for Aging
Research to T. M. and HL35724 to B. W.
EDITOR’S STATEMENT The technique described in this paper represents an approach to quantifying cell density in adherent monolayers
of cultured cells in microtiter wells that is rapid and simple and does not require radioisotopes or removal of cells. 相似文献
5.
6.
A model of maternal lipemia without hyperglycemia, in the rat, produced by high-fat feedings, was developed to study the effects of an abnormal maternal lipid homeostasis on placental transport of nutrients and possible alterations of key enzymes of energy metabolism in the liver and brain of the fetuses. Pregnant rats fed lower concentrations of fat served as controls. All studies were carried out in dams and fetuses one day prior to delivery. The dietary treatment of the dams and fetuses produced in the fetuses ketonemia as well as lipemia. Following a bolus of 14C-3-0-methyl-D-glucose to the dams, the levels of the tracer remained higher in the blood and brain of lipemic than in control fetuses. By contrast, there was a decrease in the fluxes of 14C--amino-isobutryic acid in the fetuses of lipemic dams as compared to controls. Among enzymes of energy metabolism, fetal liver glucose-6-phosphatase and succinic dehydrogenase were enhanced by lipemia. Fetal brain glucose-6-phosphatase was depressed. Thus, lipemia, as occuring in poorly controlled maternal diabetes, may be a factor in determining the access to the fetus of essential, neutral amino acids and alter the normal activity of energy metabolism enzymes in the fetus. 相似文献
7.
8.
Shannon P. Smyth Brett Nixon Amanda L. Anderson Heather C. Murray Jacinta H. Martin Lily A. MacDougall Sarah A. Robertson David A. Skerrett-Byrne John E. Schjenken 《Proteomics》2022,22(9):2100227
The seminal vesicles are male accessory sex glands that contribute the major portion of the seminal plasma in which mammalian spermatozoa are bathed during ejaculation. In addition to conveying sperm through the ejaculatory duct, seminal vesicle secretions support sperm survival after ejaculation, and influence the female reproductive tract to promote receptivity to pregnancy. Analysis of seminal vesicle fluid (SVF) composition by proteomics has proven challenging, due to its highly biased protein signature with a small subset of dominant proteins and the difficulty of solubilizing this viscous fluid. As such, publicly available proteomic datasets identify only 85 SVF proteins in total. To address this limitation, we report a new preparative methodology involving sequential solubilization of mouse SVF in guanidine hydrochloride, acetone precipitation, and analysis by label-free mass spectrometry. Using this strategy, we identified 126 SVF proteins, including 83 previously undetected in SVF. Members of the seminal vesicle secretory protein family were the most abundant, accounting for 79% of all peptide spectrum matches. Functional analysis identified inflammation and formation of the vaginal plug as the two most prominent biological processes. Other notable processes included modulation of sperm function and regulation of the female reproductive tract immune environment. Together, these findings provide a robust methodological framework for future SVF studies and identify novel proteins with potential to influence both male and female reproductive physiology. 相似文献
9.
Jocelyn Chan Joyce Chan Lily Shao Scott S. Stawicki Victoria C. Pham Rob W. Akita Marc Hafner Lisa Crocker Kebing Yu James T. Koerber Gabriele Schaefer Laetitia Comps-Agrar 《The Journal of biological chemistry》2023,299(1)
Fibroblast growth factor receptor 1 (FGFR1) is a receptor tyrosine kinase that plays a major role in developmental processes and metabolism. The dysregulation of FGFR1 through genetic aberrations leads to skeletal and metabolic diseases as well as cancer. For this reason, FGFR1 is a promising therapeutic target, yet a very challenging one due to potential on-target toxicity. More puzzling is that both agonistic and antagonistic FGFR1 antibodies are reported to exhibit similar toxicity profiles in vivo, namely weight loss. In this study, we aimed to assess and compare the mechanism of action of these molecules to better understand this apparent contradiction. By systematically comparing the binding of these antibodies and the activation or the inhibition of the major FGFR1 signaling events, we demonstrated that the molecules displayed similar properties and can behave either as an agonist or antagonist depending on the presence or the absence of the endogenous ligand. We further demonstrated that these findings translated in xenografts mice models. In addition, using time-resolved FRET and mass spectrometry analysis, we showed a functionally distinct FGFR1 active conformation in the presence of an antibody that preferentially activates the FGFR substrate 2 (FRS2)-dependent signaling pathway, demonstrating that modulating the geometry of a FGFR1 dimer can effectively change the signaling outputs and ultimately the activity of the molecule in preclinical studies. Altogether, our results highlighted how bivalent antibodies can exhibit both agonistic and antagonistic activities and have implications for targeting other receptor tyrosine kinases with antibodies. 相似文献
10.