全文获取类型
收费全文 | 2013篇 |
免费 | 255篇 |
国内免费 | 1135篇 |
出版年
2024年 | 26篇 |
2023年 | 51篇 |
2022年 | 111篇 |
2021年 | 126篇 |
2020年 | 116篇 |
2019年 | 128篇 |
2018年 | 79篇 |
2017年 | 81篇 |
2016年 | 74篇 |
2015年 | 91篇 |
2014年 | 181篇 |
2013年 | 165篇 |
2012年 | 198篇 |
2011年 | 197篇 |
2010年 | 184篇 |
2009年 | 166篇 |
2008年 | 153篇 |
2007年 | 192篇 |
2006年 | 191篇 |
2005年 | 167篇 |
2004年 | 112篇 |
2003年 | 90篇 |
2002年 | 104篇 |
2001年 | 89篇 |
2000年 | 92篇 |
1999年 | 62篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 21篇 |
1995年 | 16篇 |
1994年 | 15篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1950年 | 2篇 |
排序方式: 共有3403条查询结果,搜索用时 15 毫秒
71.
目的分析暗色真菌威尼克何德霉菌浅部皮肤及附属器感染的特征。方法收集2016年5月至2020年5月期间我科就诊的威尼克何德霉感染病例7例。总结威尼克何德霉菌的特点,分析皮肤及附属器感染病例的临床特征及诊断。结果其中4例为掌黑癣病例,临床表现均为手部单个扁平、暗棕色斑片,无明显鳞屑,界限清楚。另外3例与掌黑癣的临床表现不同,分别表现为手部湿疹样改变、指甲损害及足癣样变。结论威尼克何德霉除了可引起掌黑癣外,还可能引起手部湿疹样改变、甲真菌病及足癣样变等非掌黑癣表现,掌黑癣可通过临床表现及真菌学检查诊断。若以非掌黑癣为临床表现的威尼克何德霉感染,容易误诊漏诊,应引起临床重视。 相似文献
72.
73.
Although superhydrophobic materials have attracted much research interest in anti-icing,some controversy still exists.In this research,we report a cost-effective method used to verify the contribution of area fraction to ice adhesion strength.We tried to partially-embed siliea nanopnarticles into microscale fabrics of a commercial polyamide mesh.Then,the area fraction could be determined by altering the mesh size.Generally,the ice adhesion strength decreases as the area fraction decreases.An ice adhesion strength of~1.9 kPa and a delayed freezing time of~1048 s can be obtained.We attribute the low ice adhesion strength to the combination of superhydro-phobicity and stress concentration.The superhydrophobicity prohibits the water from penetrating into the voids of the meshes,and the small actual contact area leads to stress concentration which promotes interfacial crack propagation.Moreover,our superhydrophobic mesh simultaneously exhibis a micro-nano hierarchical structure and a partally-cmbedded structure.Therefore,the as-prepared superhydrophobic mesh retained the ieephobicity after 20 icingldeicing cycles,and maintained its superhydrophobicity even afier 60 sandpaper-abrasion cycles and a 220"C thermal treatment. 相似文献
74.
线粒体质量控制对于线粒体网络的稳态和线粒体功能的正常发挥具有重要意义。三磷酸腺苷酶家族蛋白3A(ATAD3A)是同时参与调节线粒体结构功能、线粒体动力学和线粒体自噬等重要生物学过程的线粒体膜蛋白之一。近期研究表明,ATAD3A既可与Mic60/Mitofilin和线粒体转录因子A (TFAM)等因子相互作用以维持线粒体嵴的形态和氧化磷酸化功能,又能与发动蛋白相关蛋白1 (Drp1)结合而正性/负性调节线粒体分裂,还可作为线粒体外膜转位酶(TOM)复合物和线粒体内膜转位酶(TIM)复合物之间的桥接因子而介导PTEN诱导激酶(PINK1)输入线粒体进行加工,显示出促自噬或抗自噬活性。本文对ATAD3A在调控线粒体质量控制中的作用及其机制进行了综述。 相似文献
75.
水淹对钉螺卵影响的透射电镜观察 总被引:2,自引:0,他引:2
春汛期钉螺繁殖期在洞庭湖现场进行水淹螺卵试验,观察螺卵结构的动态变化。结果显示,对照组螺卵胶膜由胶原纤维层和基底膜组成,卵细胞核大,呈圆形或椭圆形,染色质丰富,细胞内含丰富线粒体、内质网和分泌颗粒等。水淹10d时,结构尚未见明显变化;至20d时,胶膜胶原纤维横纹不清,断裂有空洞,线粒体肿胀,嵴结构不清,核内染色质减少;30d时,出现核固缩或崩解,线粒体消失。说明在螺卵发育期水淹能很快使其发生病理损 相似文献
76.
本文应用氚-烟酰苯胺标记湖北钉螺,示踪观察不同时间烟酰苯胺进入螺体组织和脏器内的分布和进入途径。结果显示,钉螺接触药物从22分钟开始检测出组织、脏器内氚含量,以后逐渐增高,至1440分钟达最高峰;合计不同时间各组织和脏器中药物含量由高至低排列次序为外套膜、胃肠、肝脏、肠内粪梗、睾丸、卵巢、鳃、神经节、心脏;转换氚含量为烟酰苯胺剂量,证实了烟酰苯胺杀螺的低用量与高效性;由单位重量组织和脏器中药物含量排位,反映出药物在螺体分布动态变化,以及药物通过消化系统、呼吸系统、外套膜表皮三条途径进入。 相似文献
77.
78.
An extracellular signal-regulated kinase 1- and 2-dependent program of chromatin trafficking of c-Fos and Fra-1 is required for cyclin D1 expression during cell cycle reentry
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mitogens activate cell signaling and gene expression cascades that culminate in expression of cyclin D1 during the G(0)-to-G(1) transition of the cell cycle. Using cell cycle arrest in response to oxidative stress, we have delineated a dynamic program of chromatin trafficking of c-Fos and Fra-1 required for cyclin D1 expression during cell cycle reentry. In serum-stimulated lung epithelial cells, c-Fos was expressed, recruited to chromatin, phosphorylated at extracellular signal-regulated kinase 1- and 2 (ERK1,2)-dependent sites, and degraded prior to prolonged recruitment of Fra-1 to chromatin. Immunostaining showed that expression of nuclear c-Fos and that of cyclin D1 are mutually exclusive, whereas nuclear Fra-1 and cyclin D1 are coexpressed as cells traverse G(1). Oxidative stress prolonged the accumulation of phospho-ERK1,2 and phospho-c-Fos on chromatin, inhibited entry of Fra-1 into the nucleus, and blocked cyclin D1 expression. After induction of the immediate-early gene response in the presence of oxidative stress, inhibition of ERK1,2 signaling promoted degradation of c-Fos, recruitment of Fra-1 to chromatin, and expression of cyclin D1. Our data indicate that termination of nuclear ERK1,2 signaling is required for an exchange of Fra-1 for c-Fos on chromatin and initiation of cyclin D1 expression at the G(0)-to-G(1) transition of the cell cycle. 相似文献
79.
Genotoxicity of hydrated sulfur dioxide on root tips of Allium sativum and Vicia faba 总被引:6,自引:0,他引:6
Genotoxicity of sulfur dioxide (SO(2)) and its hydrates (bisulfite and sulfite) in human lymphocytes and other mammalian cells have been found earlier in our laboratory. In the present studies, we used Allium stavium and Vicia faba cytogenetic tests, which are the highly sensitive and simple plant bioassays. A mixture of sodium bisulfite and sodium sulfite (1:3), at various concentrations from 1 x 10(-4) to 2 x 10(-3)M was used for the treatment. Genotoxicity was expressed in terms of anaphase aberration (AA) frequencies in the Vicia-AA test and in terms of micronuclei (MCN) frequencies in both Vicia-MCN test and Alllium-MCN test. On average, the results showed a 1.7-3.9-fold increase of AA frequencies and a 3.5-4.5-fold increase of MCN frequencies in Vicia root tips as compared with the negative control. Similarly, results of Allium-MCN test also showed a significant increase in MCN frequencies in the treated samples. In addition, pycnotic cells (PNC) appeared in Allium root tips of treated groups. The frequencies of MCN, AA and PNC increased dose-dependently and the cell cycle delayed at the same time in bisulfite treated samples. Results of the present study suggest that the Vicia and Allium cytogenetic bioassays are efficient, simple and reproducible in genotoxicity studies of bisulfite. 相似文献
80.
Coronin 3 is a ubiquitously expressed member of the coronin protein family in mammals. In fibroblasts and HEK 293 cells, it is localized both in the cytosol and in the submembranous cytoskeleton, especially at lamellipodia and membrane ruffles. The carboxyl terminus of all coronins contains a coiled coil suggested to mediate dimerization. We show here that in contrast to other coronin homologues, the recombinant human coronin 3 carboxyl terminus forms oligomers rather than dimers, and that this part is sufficient to bind to and cross-link F-actin in vitro. The carboxyl terminus alone also conferred membrane association in vivo, and removal of the coiled coil abolished membrane localization but not in vitro F-actin binding. Coronin 3 is exclusively extracted as an oligomer from both the cytosol and the membrane fraction. Because oligomerization was not reported for other coronins, it might be a key feature governing coronin 3-specific functions. Cytosolic coronin 3 showed a high degree of phosphorylation, which is likely to regulate the subcellular localization of the protein. 相似文献