全文获取类型
收费全文 | 1674篇 |
免费 | 164篇 |
国内免费 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 32篇 |
2021年 | 41篇 |
2020年 | 42篇 |
2019年 | 32篇 |
2018年 | 46篇 |
2017年 | 33篇 |
2016年 | 58篇 |
2015年 | 84篇 |
2014年 | 101篇 |
2013年 | 119篇 |
2012年 | 142篇 |
2011年 | 138篇 |
2010年 | 80篇 |
2009年 | 92篇 |
2008年 | 126篇 |
2007年 | 94篇 |
2006年 | 98篇 |
2005年 | 91篇 |
2004年 | 84篇 |
2003年 | 79篇 |
2002年 | 61篇 |
2001年 | 14篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 17篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1975年 | 1篇 |
1968年 | 1篇 |
1921年 | 2篇 |
排序方式: 共有1841条查询结果,搜索用时 15 毫秒
91.
The conventional organic chemistry concept of chirality relates to single molecules. This article deals with cases in which exciton chirality is generated by the interaction of associated carotenoids. The handed property responsible for exciton signals in these systems is due to the alignment of neighboring molecules held together by secondary chemical forces. Their mutual positions are characterized by the overlay angle. Experimental manifestation is obtained by spectroscopic studies on carotenoid aggregates. Compared to molecular spectra, both UV/visible and circular dichroism spectroscopic observations reveal modified absorption bands and induced Cotton effects of opposite sign (exciton couplets), respectively. A new term, "supramolecular exciton chirality," is suggested for these phenomena, allowing the detection of weak chemical interactions not readily accessible for experimental studies, although highly important in the mechanism of biological processes. 相似文献
92.
93.
Sophie Camilleri-Broët Holly Vanderwerff Elizabeth Caldwell David Hockenbery 《Experimental cell research》1998,239(2):277
Recent studies have shown that reduction in mitochondrial membrane potential (ΔΨm) and generation of reactive oxygen species are early events in apoptosis. In this study, we present two different models of apoptotic cell death, Chinese hamster ovary (CHO) cells treated with aphidicolin and dexamethasone-treated 2B4 T-cell hybridoma cells, which display opposing mitochondrial changes. CHO cells arrested at G1/S with aphidicolin have a progressive increase in mitochondria mass and number, assessed by flow cytometry and fluorescent microscopy with mitochondria-specific probes. The increase in mitochondrial mass was not accompanied by a gain in net cellular mitochondrial membrane potential, consistent with an accumulation of relatively depolarized mitochondria. Fluorescent microscopy demonstrated an increased content of low ΔΨmmitochondria in aphidicolin-treated CHO cells, but high ΔΨmmitochondria were also present and remained stable in number. Mitochondrial mass correlated with decreased clonogenicity of aphidicolin-treated CHO cells. Cycloheximide prevented both the proliferation of mitochondria and subsequent cell death. In contrast, dexamethasone treatment of 2B4 T-cell hybridoma cells caused a decrease in ΔΨmwithout mitochondrial proliferation. Cycloheximide and Bcl-2 overexpression inhibited the loss of ΔΨm, as well as apoptosis. In both models, cell death was associated with a decrease in mitochondrial potential relative to mitochondrial mass, suggesting that an accumulation of damaged or dysfunctional mitochondria had occurred. 相似文献
94.
95.
96.
97.
98.
99.
100.
Andrew Filer Philipp Antczak Greg N. Parsonage Holly M. Legault Margot O’Toole Mark J. Pearson Andrew M. Thomas Dagmar Scheel-Toellner Karim Raza Christopher D. Buckley Francesco Falciani 《PloS one》2015,10(3)
Synovial fibroblasts in persistent inflammatory arthritis have been suggested to have parallels with cancer growth and wound healing, both of which involve a stereotypical serum response programme. We tested the hypothesis that a serum response programme can be used to classify diseased tissues, and investigated the serum response programme in fibroblasts from multiple anatomical sites and two diseases. To test our hypothesis we utilized a bioinformatics approach to explore a publicly available microarray dataset including rheumatoid arthritis (RA), osteoarthritis (OA) and normal synovial tissue, then extended those findings in a new microarray dataset representing matched synovial, bone marrow and skin fibroblasts cultured from RA and OA patients undergoing arthroplasty. The classical fibroblast serum response programme discretely classified RA, OA and normal synovial tissues. Analysis of low and high serum treated fibroblast microarray data revealed a hierarchy of control, with anatomical site the most powerful classifier followed by response to serum and then disease. In contrast to skin and bone marrow fibroblasts, exposure of synovial fibroblasts to serum led to convergence of RA and OA expression profiles. Pathway analysis revealed three inter-linked gene networks characterising OA synovial fibroblasts: Cell remodelling through insulin-like growth factors, differentiation and angiogenesis through _3 integrin, and regulation of apoptosis through CD44. We have demonstrated that Fibroblast serum response signatures define disease at the tissue level, and that an OA specific, serum dependent repression of genes involved in cell adhesion, extracellular matrix remodelling and apoptosis is a critical discriminator between cultured OA and RA synovial fibroblasts. 相似文献