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221.
222.
以天蓝色链霉菌的whiB基因为探针,从圈卷产色链霉菌7100的总DNA部分文库中克隆了含有whiB同源序列的28kb DNA片段,并对其中的14kb片段进行了序列测定。序列分析表明,该片段含有一个完整的开放阅读框—sawE。预测的蛋白质结构及同源性分析显示,sawE与天蓝色链霉菌孢子形成早期的关键基因whiB高度同源,编码产物为一个调控蛋白。sawE的破坏使圈卷产色链霉菌7100的分化终止在气生菌丝阶段,在延长培养时间的情况下仍保持白色的表型,菌丝不能分隔,不能形成成熟的灰色孢子,结果表明sawE基因是一个与圈卷产色链霉菌分化有关的重要基因。 相似文献
223.
Genome-wide regulation of 5hmC, 5mC, and gene expression by Tet1 hydroxylase in mouse embryonic stem cells 总被引:2,自引:0,他引:2
Xu Y Wu F Tan L Kong L Xiong L Deng J Barbera AJ Zheng L Zhang H Huang S Min J Nicholson T Chen T Xu G Shi Y Zhang K Shi YG 《Molecular cell》2011,42(4):451-464
DNA methylation at the 5 position of cytosine (5mC) in the mammalian genome is a key epigenetic event critical for various cellular processes. The ten-eleven translocation (Tet) family of 5mC-hydroxylases, which convert 5mC to 5-hydroxymethylcytosine (5hmC), offers a way for dynamic regulation of DNA methylation. Here we report that Tet1 binds to unmodified C or 5mC- or 5hmC-modified CpG-rich DNA through its CXXC domain. Genome-wide mapping of Tet1 and 5hmC reveals mechanisms by which Tet1 controls 5hmC and 5mC levels in mouse embryonic stem cells (mESCs). We also uncover a comprehensive gene network influenced by Tet1. Collectively, our data suggest that Tet1 controls DNA methylation both by binding to CpG-rich regions to prevent unwanted DNA methyltransferase activity, and by converting 5mC to 5hmC through hydroxylase activity. This Tet1-mediated antagonism of CpG methylation imparts differential maintenance of DNA methylation status at Tet1 targets, ultimately contributing to mESC differentiation and the onset of embryonic development. 相似文献
224.
本文采用间接免疫荧光法(IF),RPHA法,ELISA法及斑点杂交技术检测10例无症状HB-sAg携带者及89例乙肝病人尿细胞中的HBsAg、HBeAg及HBVDNA,发现尿细胞中有HBsAg、HBeAg、HBVDNA存在。结果提示:乙肝无症状携带者及乙肝病人尿细胞中具有HBsAg、HBeAg、HBVDNA,因此更进一步证实尿液具有传染性。 相似文献
225.
用染料修饰吐温80液—固萃取体系从猪心肌匀浆液中分离纯化心肌黄酶 总被引:2,自引:0,他引:2
用三嗪类染料 Cibacron Blue F3G-A修饰的吐温80,与吐温80、硫酸被构成液-固萃取体系,从猪心肌匀浆液中分离纯化心肌黄酶。研究了吐温80染料修饰物在吐温80相中所占的比例、分相盐浓度、溶液的酸度、匀浆液的加入量等对匀浆液中酶及杂蛋白在两相中分配的影响。在室温条件下,酶选择性地进入吐温80固相,杂蛋白主要留在盐水相。匀浆液中心肌黄酶的酶活力平均收得率为81.4%,一步纯化倍数为6.6。降低盐浓度,提高盐水相酸度,能使酶从吐温80固相反萃到盐水相。 相似文献
226.
X inactivation in the mouse embryo deficient for Dnmt1: distinct effect of hypomethylation on imprinted and random X inactivation 总被引:1,自引:0,他引:1
It has been suggested that DNA methylation plays a crucial role in genomic imprinting and X inactivation. Using DNA methyltransferase 1 (Dnmt1)-deficient mouse embryos carrying X-linked lacZ transgenes, we studied the effects of genomic demethylation on X inactivation. Based on the expression pattern of lacZ, the imprinted X inactivation in the visceral endoderm, a derivative of the extraembryonic lineage, was unaffected in Dnmt1 mutant embryos at the time other imprinted genes showed aberrant expression. Random X inactivation in the embryonic lineage of Dnmt1 mutant embryos, however, was unstable as a result of hypomethylation, causing reactivation of, at least, one lacZ transgene that had initially been repressed. Our results suggest that maintenance of imprinted X inactivation in the extraembryonic lineage can tolerate extensive demethylation while normal levels of methylation are required for stable maintenance of X inactivation in the embryonic lineage. 相似文献
227.
228.
Leptin, the product of the Obese (Lep) gene, orchestrates behavioral and metabolic responses to nutrient intake. Here, we demonstrate tissue-specific autoregulation of Lep. Moderate increases in circulating leptin considerably decreased Lep expression in adipose tissue and induced lep expression in skeletal muscle, a tissue that normally does not express this gene. Changes in nutrient availability resulted in rapid alterations in Lep autoregulation. These findings demonstrate negative feedback regulation of Lep in fat, and indicate that leptin secretion can function as a vehicle of 'cross-talk' between adipose tissue and skeletal muscle, leading to tissue-specific modulation of the 'leptin signal'. 相似文献
229.
Jianguo Tan Youfei Zheng Xu Tang Changyi Guo Liping Li Guixiang Song Xinrong Zhen Dong Yuan Adam J. Kalkstein Furong Li Heng Chen 《International journal of biometeorology》2010,54(1):75-84
With global warming forecast to continue into the foreseeable future, heat waves are very likely to increase in both frequency and intensity. In urban regions, these future heat waves will be exacerbated by the urban heat island effect, and will have the potential to negatively influence the health and welfare of urban residents. In order to investigate the health effects of the urban heat island (UHI) in Shanghai, China, 30 years of meteorological records (1975–2004) were examined for 11 first- and second-order weather stations in and around Shanghai. Additionally, automatic weather observation data recorded in recent years as well as daily all-cause summer mortality counts in 11 urban, suburban, and exurban regions (1998–2004) in Shanghai have been used. The results show that different sites (city center or surroundings) have experienced different degrees of warming as a result of increasing urbanization. In turn, this has resulted in a more extensive urban heat island effect, causing additional hot days and heat waves in urban regions compared to rural locales. An examination of summer mortality rates in and around Shanghai yields heightened heat-related mortality in urban regions, and we conclude that the UHI is directly responsible, acting to worsen the adverse health effects from exposure to extreme thermal conditions. 相似文献
230.
Bhawana George Neeraj Jain Pei Fen Chong Jun Hou Tan Thirumaran Thanabalu 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2014
Skeletal muscle formation is a multistep process involving proliferation, differentiation, alignment and fusion of myoblasts to form myotubes which fuse with additional myoblast to form myofibers. Toca-1 (Transducer of Cdc42-dependent actin assembly), is an adaptor protein which activates N-WASP in conjunction with Cdc42 to facilitate membrane invagination, endocytosis and actin cytoskeleton remodeling. Expression of Toca-1 in mouse primary myoblasts and C2C12 myoblasts was up-regulated on day 1 of differentiation and subsequently down-regulated during differentiation. Knocking down Toca-1 expression in C2C12 cells (Toca-1KD cells) resulted in a significant decrease in myotube formation and expression of shRNA-resistant Toca-1 in Toca-1KD cells rescued the myogenic defect, suggesting that the knockdown was specific and Toca-1 is essential for myotube formation. Toca-1KD cells exhibited elongated spindle-like morphology, expressed myogenic markers (MyoD and MyHC) and localized N-Cadherin at cell periphery similar to control cells suggesting that Toca-1 is not essential for morphological changes or expression of proteins critical for differentiation. Toca-1KD cells displayed prominent actin fibers suggesting a defect in actin cytoskeleton turnover necessary for cell–cell fusion. Toca-1KD cells migrated faster than control cells and had a reduced number of vinculin patches similar to N-WASPKO MEF cells. Transfection of N-WASP-expressing plasmid into Toca-1KD cells restored myotube formation of Toca-1KD cells. Thus, our results suggest that Toca-1KD cells have defects in formation of myotubes probably due to reduced activity of actin cytoskeleton regulators such as N-WASP. This is the first study to identify and characterize the role of Toca-1 in myogenesis. 相似文献