全文获取类型
收费全文 | 284篇 |
免费 | 24篇 |
专业分类
308篇 |
出版年
2024年 | 3篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 19篇 |
2002年 | 17篇 |
2001年 | 20篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有308条查询结果,搜索用时 15 毫秒
231.
T Khosla 《BMJ (Clinical research ed.)》1984,289(6443):497-498
232.
233.
234.
235.
Effects of gonadal and adrenal androgens in a novel androgen-responsive human osteoblastic cell line
Lorenz C. Hofbauer Kevin C. Hicok Sundeep Khosla 《Journal of cellular biochemistry》1998,71(1):96-108
While androgens have important skeletal effects, the mechanism(s) of androgen action on bone remain unclear. Current osteoblast models to study androgen effects have several limitations, including the presence of heterogeneous cell populations. In this study, we examined the effects of androgens on the proliferation and differentiation of a novel human fetal osteoblastic cell line (hFOB/AR-6) that expresses a mature osteoblast phenotype and a physiological number (∼4,000/nucleus) of androgen receptors (AR). Treatment with 5α-dihydrotestosterone (5α-DHT) inhibited the proliferation of hFOB/AR-6 cells in a dose-dependent fashion, while it had no effect on the proliferation of hFOB cells, which express low levels of AR (<200/nucleus). In hFOB/AR-6 cells, co-treatment with the specific AR antagonist, hydroxyflutamide abolished 5α-DHT-induced growth inhibition. Steady-state levels of transforming growth factor-β1 (TGF-β1) and TGF-β-induced early gene (TIEG) mRNA decreased after treatment of hFOB/AR-6 cells with 5α-DHT, suggesting a role for the TGF-β1-TIEG pathway in mediating 5α-DHT-induced growth inhibition of hFOB/AR-6 cells. In support of this, co-treatment of hFOB/AR-6 cells with TGF-β1 (40 pg/ml) reversed the 5α-DHT-induced growth inhibition, whereas TGF-β1 alone at this dose had no effect on hFOB/AR-6 cell proliferation. Furthermore, treatment of hFOB/AR-6 cells with 5α-DHT and testosterone (10−8 M) inhibited basal and 1,25-(OH)2D3-induced alkaline phosphatase (ALP) activity and type I collagen synthesis without affecting osteocalcin production. Thus, in this fetal osteoblast cell line expressing a physiological number of AR, androgens decrease proliferation and the expression of markers associated with osteoblast differentiation. These studies suggest that the potential anabolic effect of androgens on bone may not be mediated at the level of the mature osteoblast. J. Cell. Biochem. 71:96–108, 1998. © 1998 Wiley-Liss, Inc. 相似文献
236.
237.
Biosynthesis of polyketides in heterologous hosts. 总被引:3,自引:0,他引:3
Polyketide natural products show great promise as medicinal agents. Typically the products of microbial secondary biosynthesis, polyketides are synthesized by an evolutionarily related but architecturally diverse family of multifunctional enzymes called polyketide synthases. A principal limitation for fundamental biochemical studies of these modular megasynthases, as well as for their applications in biotechnology, is the challenge associated with manipulating the natural microorganism that produces a polyketide of interest. To ameliorate this limitation, over the past decade several genetically amenable microbes have been developed as heterologous hosts for polyketide biosynthesis. Here we review the state of the art as well as the difficulties associated with heterologous polyketide production. In particular, we focus on two model hosts, Streptomyces coelicolor and Escherichia coli. Future directions for this relatively new but growing technological opportunity are also discussed. 相似文献
238.
The mechanical response under uniaxial compression of collagen discs, made from freeze-dried collagen reconstituted at acid pH, was investigated at 22, 29.5 and 35 degrees C. The pH during compression was maintained at the physiological level of 7.4. The fluid transport model developed by Bert (1970) was fitted to the data. Assumptions, made in the development of the model, were tested and the range of reliability of the model is discussed. The two fitting parameters of the model were found to be stronger functions of hydration than was previously reported. The compressive response of collagen was found to be only weakly influenced by temperature. At 35 degrees C there was evidence of thermal degradation. Some creep was noted at times greater than five half-times, but no attempt was made to quantify it. 相似文献
239.
240.