全文获取类型
收费全文 | 709篇 |
免费 | 61篇 |
国内免费 | 10篇 |
专业分类
780篇 |
出版年
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 14篇 |
2017年 | 16篇 |
2016年 | 15篇 |
2015年 | 19篇 |
2014年 | 18篇 |
2013年 | 29篇 |
2012年 | 25篇 |
2011年 | 30篇 |
2010年 | 27篇 |
2009年 | 37篇 |
2008年 | 31篇 |
2007年 | 25篇 |
2006年 | 32篇 |
2005年 | 13篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1989年 | 6篇 |
1985年 | 6篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 7篇 |
1974年 | 5篇 |
1959年 | 7篇 |
1958年 | 23篇 |
1957年 | 26篇 |
1956年 | 26篇 |
1955年 | 22篇 |
1954年 | 22篇 |
1953年 | 13篇 |
1952年 | 13篇 |
1951年 | 10篇 |
1950年 | 9篇 |
排序方式: 共有780条查询结果,搜索用时 15 毫秒
1.
2.
3.
Improved negative staining of microfilament arrangements in detergent-extracted Physarum amoeboflagellates 总被引:2,自引:0,他引:2
A motile, lamellipodium-like structure, the ridge, forms as amoeboflagellate cells of Physarum polycephalum release from a substratum and begin swimming in fluid. Actin microfilaments form a distinct laminar core within the ridge; they are seen as a sparse, disordered meshwork in cytoskeletons prepared by conventional methods using uranyl acetate negative staining [10]. Preservation and visualization of these filaments and their arrangements improved considerably when cytoskeletons were imaged with phosphotungstic acid buffered with ammonium hydroxide (PTA(NH4]. Microfilaments within ridge cytoskeletons were found to form loose bundles and criss-crossing, 'meshwork' arrays several layers deep. Differences could be detected in morphology and detailed arrangement of microfilaments within cytoskeletons prepared in the presence of phalloidin. PTA(NH4) may be useful for studies of cytoskeletal elements and their rearrangements in dynamic, motile regions of cells. 相似文献
4.
Neural control of the expression of a Ca2+-activated K+ channel involved in the induction of myotonic-like characteristics 总被引:2,自引:0,他引:2
Beatriz U. Ramírez Maria Isabel Behrens Cecilia Vergara 《Cellular and molecular neurobiology》1996,16(1):39-49
Summary 1. Expression of the apamin-sensitive K+ channel (SK+) in rat skeletal muscle is neurally regulated. The regulatory effect of the nerve over the expression of some muscle ion
channels has been attributed to the electrical activity triggered by the nerve and/or to a trophic effect of some molecules
transported from the soma to the axonal endings.
2. SK+ channels apparently are involved in myotonic dystrophy (MD), therefore understanding the factors that regulate their expression
may ultimately have important clinical relevance.
3. To establish if axoplasmic transport is involved in this process, we used two experimental approaches in adult rats: (a)
Both sciatic nerves were severed, leaving a short or a long nerve stump attached to the anterior tibialis (AT). (b) Colchicine
or vinblastine (VBL), two axonal transport blockers of different potencies, was applied on one leg to the sciatic nerve. To
determine whether electrical activity affects the expression of SK+ channels, denervated AT were directly stimulated. The corresponding contralateral muscles were used as controls.
4. With these experimental conditions we measured (a) apamin binding to muscle membranes, (b) muscle contractile characteristics,
and (c) electromyographic activity.
5. In the short- and long-nerve stump experiments, 5 days after denervation125I-apamin binding to AT membranes was 2.0 times higher in the short-stump side. This difference disappeared at longer times.
The delayed expression of SK+ channels in the muscle left with a longer nerve stump can be attributed to the extra axoplasm contained in the longer stump,
which maintains a normally repressive signal for a longer period of time. Ten to 15 days after application of axonal transport
blockers we found that the muscle half-relaxation time increased in the drug-treated side and apamin partially reverted the
prolonged relaxation. Myotonic-like discharges specifically blockable by apamin were always present in the drug-treated leg.125I-Apamin binding, which is undetectable in a microsomal preparation from hind leg control muscles, was increased in the drug-treated
preparations. Apamin binding to denervated and stimulated AT muscles was lower than in the contralateral unstimulated muscles
[3.3±1.0 vs 6.8±0.8 (n=4) fmol/mg protein].
6. Our results demonstrate that electrical activity and axoplasmic transport are involved in the control of expression of
SK+ in rat skeletal muscle. However, the increased expression of this channel induces myotonic-like characteristics that are
reversed by apamin. This myotonic activity could be a model for MD. 相似文献
5.
6.
7.
8.
9.
10.