全文获取类型
收费全文 | 6802篇 |
免费 | 460篇 |
国内免费 | 1篇 |
出版年
2023年 | 65篇 |
2022年 | 67篇 |
2021年 | 174篇 |
2020年 | 149篇 |
2019年 | 152篇 |
2018年 | 192篇 |
2017年 | 192篇 |
2016年 | 248篇 |
2015年 | 383篇 |
2014年 | 372篇 |
2013年 | 496篇 |
2012年 | 593篇 |
2011年 | 578篇 |
2010年 | 357篇 |
2009年 | 294篇 |
2008年 | 402篇 |
2007年 | 374篇 |
2006年 | 307篇 |
2005年 | 298篇 |
2004年 | 296篇 |
2003年 | 227篇 |
2002年 | 220篇 |
2001年 | 63篇 |
2000年 | 46篇 |
1999年 | 46篇 |
1998年 | 80篇 |
1997年 | 52篇 |
1996年 | 38篇 |
1995年 | 35篇 |
1994年 | 36篇 |
1993年 | 40篇 |
1992年 | 27篇 |
1991年 | 20篇 |
1990年 | 27篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 34篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1975年 | 7篇 |
1973年 | 12篇 |
1972年 | 8篇 |
1968年 | 11篇 |
1961年 | 8篇 |
排序方式: 共有7263条查询结果,搜索用时 15 毫秒
81.
82.
Evidence is presented indicating that intact plants of Hordeum vulgare degrade [α- 14C]hordenine to 14CO 2. 相似文献
83.
E Angulo J Moya 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1989,27(2):113-119
In the present paper we investigated the fine structure of terrestial slug Arion ater (L.) Interacisternal microtubules were formed in Arion ater, however they do not correspond to interacisternal polycylinders because they differ in size and they are not continuous with the membrane cistern. From our study it may be concluded that these intracisternal microtubules suggest an accumulation of protein. 相似文献
84.
85.
Beatriz Mesa-Pereira Carlos Medina Eva María Camacho Amando Flores Eduardo Santero 《PloS one》2013,8(10)
In order to further characterize its role in pathogenesis and to establish whether its overproduction can lead to eukaryotic tumor cell death, Salmonella strains able to express its virulence factor SpvB (an ADP-ribosyl transferase enzyme) in a salicylate-inducible way have been constructed and analyzed in different eukaryotic tumor cell lines. To do so, the bacterial strains bearing the expression system have been constructed in a ∆purD background, which allows control of bacterial proliferation inside the eukaryotic cell. In the absence of bacterial proliferation, salicylate-induced SpvB production resulted in activation of caspases 3 and 7 and apoptotic cell death. The results clearly indicated that controlled SpvB production leads to F-actin depolimerization and either G1/S or G2/M phase arrest in all cell lines tested, thus shedding light on the function of SpvB in Salmonella pathogenesis. In the first place, the combined control of protein production by salicylate regulated vectors and bacterial growth by adenine concentration offers the possibility to study the role of Salmonella effectors during eukaryotic cells infection. In the second place, the salicylate-controlled expression of SpvB by the bacterium provides a way to evaluate the potential of other homologous or heterologous proteins as antitumor agents, and, eventually to construct novel potential tools for cancer therapy, given that Salmonella preferentially proliferates in tumors. 相似文献
86.
Luiz Henrique Soares de Andrade Wilson Max Almeida Monteiro de Moraes Eduardo Hiroshi Matsuo Junior Elizabeth de Orleans Carvalho de Moura Hanna Karen Moreira Antunes Jairo Montemor Ednei Luiz Antonio Danilo Sales Bocalini Andrey Jorge Serra Paulo José Ferreira Tucci Patricia Chakur Brum Alessandra Medeiros 《Molecular and cellular biochemistry》2015,402(1-2):193-202
87.
88.
Mohammad Haeri Peter D. Calvert Eduardo Solessio Edward N. Pugh Jr Barry E. Knox 《PloS one》2013,8(11)
The rod outer segment (OS), comprised of tightly stacked disk membranes packed with rhodopsin, is in a dynamic equilibrium governed by a diurnal rhythm with newly synthesized membrane inserted at the OS base balancing membrane loss from the distal tip via disk shedding. Using transgenic Xenopus and live cell confocal imaging, we found OS axial variation of fluorescence intensity in cells expressing a fluorescently tagged rhodopsin transgene. There was a light synchronized fluctuation in intensity, with higher intensity in disks formed at night and lower intensity for those formed during the day. This fluctuation was absent in constant light or dark conditions. There was also a slow modulation of the overall expression level that was not synchronized with the lighting cycle or between cells in the same retina. The axial variations of other membrane-associated fluorescent proteins, eGFP-containing two geranylgeranyl acceptor sites and eGFP fused to the transmembrane domain of syntaxin, were greatly reduced or not detectable, respectively. In acutely light-adapted rods, an arrestin-eGFP fusion protein also exhibited axial variation. Both the light-sensitive Rho-eGFP and arrestin-eGFP banding were in phase with the previously characterized birefringence banding (Kaplan, Invest. Ophthalmol. Vis. Sci. 21, 395–402 1981). In contrast, endogenous rhodopsin did not exhibit such axial variation. Thus, there is an axial inhomogeneity in membrane composition or structure, detectable by the rhodopsin transgene density distribution and regulated by the light cycle, implying a light-regulated step for disk assembly in the OS. The impact of these results on the use of chimeric proteins with rhodopsin fused to fluorescent proteins at the carboxyl terminus is discussed. 相似文献
89.
90.
Alice Kunzler Eduardo Antônio Kolling Jeferson Delgado da Silva-Jr Juciano Gasparotto Matheus Augusto de Bittencourt Pasquali José Cláudio Fonseca Moreira Daniel Pens Gelain 《Neurochemical research》2017,42(10):2788-2797
Retinoids (vitamin A and derivatives) are recognized as essential factors for central nervous system (CNS) development. Retinol (vitamin A) also was postulated to be a major antioxidant component of diet as it modulates reactive species (RS) production and oxidative stress in biological systems. Oxidative stress plays a major role either in pathogenesis or development of neurodegenerative diseases, or even in both. Here we investigate the role of retinol supplementation to human neuron-derived SH-SY5Y cells over RS production and biochemical markers associated to neurodegenerative diseases expressed at neuronal level in Parkinson’s disease and Alzheimer’s disease: α-synuclein, β-amyloid peptide, tau phosphorylation and RAGE. Retinol treatment (24 h) impaired cell viability and increased intracellular RS production at the highest concentrations (7 up to 20 µM). Antioxidant co-treatment (Trolox 100 µM) rescued cell viability and inhibited RS production. Furthermore, retinol (10 µM) increased the levels of α-synuclein, tau phosphorylation at Ser396, β-amyloid peptide and RAGE. Co-treatment with antioxidant Trolox inhibited the increased in RAGE, but not the effect of retinol on α-synuclein, tau phosphorylation and β-amyloid peptide accumulation. These data indicate that increased availability of retinol to neurons at levels above the cellular physiological concentrations may induce deleterious effects through diverse mechanisms, which include oxidative stress but also include RS-independent modulation of proteins associated to progression of neuronal cell death during the course of neurodegenerative diseases. 相似文献