全文获取类型
收费全文 | 192篇 |
免费 | 43篇 |
专业分类
235篇 |
出版年
2014年 | 6篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1995年 | 2篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1969年 | 6篇 |
1968年 | 9篇 |
1967年 | 5篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1962年 | 4篇 |
1961年 | 4篇 |
1960年 | 3篇 |
1958年 | 3篇 |
1956年 | 4篇 |
1951年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有235条查询结果,搜索用时 0 毫秒
151.
152.
1. The submicroscopic organization of nerve axons from R. pipiens and R. catesbiana has been studied by means of polarizing and electron microscopes. 2. In measurements on a series of 85 fresh myelinated axons from which the sheaths had been removed average values were obtained for the total birefringence, +2.5 x 10–4, the form birefringence, +1.4 x 10–4, and the refractive index of the oriented component, 1.523. The average partial volume occupied by axially oriented filaments was computed to be 0.69 per cent. 3. Electron micrographs of fixed myelinated axons demonstrate an average of 93 axially oriented neuroprotofibrils per square micron of cross-section. The neuroprotofibrils are approximately 90 A in diameter, of indefinite length, and occupy a computed partial volume of 0.59 per cent. 4. Mitochondria, neuroprotofibrils, endoplasmic reticulum, and dense particles are seen in electron micrographs of both myelinated and unmyelinated nerve axons. 5. It is concluded that the neuroprotofibrils are present in the living nerve, that they play an important but undetermined role in nerve function, and that these structures are not an artifact of osmium tetroxide fixation. 相似文献
153.
154.
155.
156.
Paraxial protocadherin coordinates cell polarity during convergent extension via Rho A and JNK 下载免费PDF全文
Unterseher F Hefele JA Giehl K De Robertis EM Wedlich D Schambony A 《The EMBO journal》2004,23(16):3259-3269
Convergent extension movements occur ubiquitously in animal development. This special type of cell movement is controlled by the Wnt/planar cell polarity (PCP) pathway. Here we show that Xenopus paraxial protocadherin (XPAPC) functionally interacts with the Wnt/PCP pathway in the control of convergence and extension (CE) movements in Xenopus laevis. XPAPC functions as a signalling molecule that coordinates cell polarity of the involuting mesoderm in mediolateral orientation and thus selectively promotes convergence in CE movements. XPAPC signals through the small GTPases Rho A and Rac 1 and c-jun N-terminal kinase (JNK). Loss of XPAPC function blocks Rho A-mediated JNK activation. Despite common downstream components, XPAPC and Wnt/PCP signalling are not redundant, and the activity of both, XPAPC and PCP signalling, is required to coordinate CE movements. 相似文献
157.
We analyzed the Chordin requirement in Xenopus development. Targeting of both chordin Xenopus laevis pseudoalleles with morpholino antisense oligomers (Chd-MO) markedly decreased Chordin production. Embryos developed with moderately reduced dorsoanterior structures and expanded ventroposterior tissues, phenocopying the zebrafish chordino mutant. A strong requirement for Chordin in dorsal development was revealed by experimental manipulations. First, dorsalization by lithium chloride treatment was completely blocked by Chd-MO. Second, Chd-MO inhibited elongation and muscle differentiation in Activin-treated animal caps. Third, Chd-MO completely blocked the induction of the central nervous system (CNS), somites, and notochord by organizer tissue transplanted to the ventral side of host embryos. Unexpectedly, transplantations into the dorsal side revealed a cell-autonomous requirement of Chordin for neural plate differentiation. 相似文献
158.
A Al-Omar S Abdou L De Robertis A Marsura C Finance 《Bioorganic & medicinal chemistry letters》1999,9(8):1115-1120
Ability of molecular complexes of [Doxorubicin (DX)-cyclodextrin (Cd)] to enhance the anticellular activity of antineoplastic drug Doxorubicin and to reverse its multidrug resistance has been investigated. A spectroscopic study of the alpha, beta, and gamma-[DX-Cds] complexes has been investigated in relation to their biological effects on a multidrug resistant (MDR) human rectal adenocarcinoma cell line (HRT-18). A ten fold enhancement of DX anticellular activity in presence of beta-cyclodextrin alone was detected. 相似文献
159.
Di Bernardo G Galderisi U Del Gaudio S D'Aniello A Lanave C De Robertis MT Cascino A Cipollaro M 《Journal of cellular physiology》2004,199(2):200-205
DNA extracted from the skeletons of five equids discovered in a Pompeii stable and of a horse found in Herculaneum was investigated. Amino acid racemization level was consistent with the presence of DNA. Post‐mortem base modifications were excluded by sequencing a 146 bp fragment of the 16S rRNA mitochondrial gene. Sequencing of a 370 bp fragment of mitochondrial (mt)DNA control region allowed the construction of a phylogenetic tree that, along with sequencing of nuclear genes (epsilon globin, gamma interferon, and p53) fragments, gave us the possibility to address some questions puzzling archaeologists. What animals—donkeys, horses, or crossbreeds—were they? And, given they had been evidently assigned to one specific job, were they all akin or were they animals with different mitochondrial haplotypes? The conclusions provided by molecular analysis show that the Pompeii remains are those of horses and mules. Furthermore one of the equids (CAV5) seems to belong to a haplotype, which is either not yet documented in the GenBank or has since disappeared. As its characteristics closely recall those of donkeys, which is the out group chosen to construct the tree, that appears to have evolved within the Equidae family much earlier than horses, this assumption seems to be nearer the truth. J. Cell. Physiol. 199: 200–205, 2004© 2003 Wiley‐Liss, Inc. 相似文献
160.