全文获取类型
收费全文 | 595篇 |
免费 | 63篇 |
国内免费 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 17篇 |
2019年 | 30篇 |
2018年 | 37篇 |
2017年 | 28篇 |
2016年 | 35篇 |
2015年 | 36篇 |
2014年 | 44篇 |
2013年 | 42篇 |
2012年 | 60篇 |
2011年 | 41篇 |
2010年 | 29篇 |
2009年 | 25篇 |
2008年 | 30篇 |
2007年 | 25篇 |
2006年 | 27篇 |
2005年 | 21篇 |
2004年 | 28篇 |
2003年 | 20篇 |
2002年 | 7篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有681条查询结果,搜索用时 78 毫秒
91.
胰腺是一个重要的内外分泌混合腺, 胰腺发生损伤后能够再生。为了探讨胰腺活体细胞世系追踪的方法和胰腺损伤后再生细胞的来源,分别通过胰腺伤口涂抹并胰内注射、尾静脉注射及腹腔注射三种方法, 利用假型反转录病毒对成体小鼠大部分切除后胰腺的细胞进行世系追踪。结果发现在活体条件下, 与尾静脉注射及腹腔注射法相比, 胰腺伤口涂抹并胰腺内注射反转录病毒的方法能够更有效的标记胰腺细胞; 而且, 通过对标记细胞的世系追踪研究证明, 在胰腺损伤后, 胰腺腺泡细胞能够接受损伤信号刺激发生再生。为今后进一步利用反转录假病毒对活体胰腺进行细胞命运追踪研究奠定基础, 为利用反转录病毒载体进行胰腺疾病的基因治疗提供线索。 相似文献
92.
93.
The objective of this study was to determine the effects of chondroitin sulfate C (CS-C) on sperm capacitation and fertilization parameters in vitro in pigs. Frozen-thawed ejaculated pig sperm (semen S-484) were incubated with fertilization medium containing CS-C (0-2mg/ml) for 1h and the capacitation rate with chlorotetracycline (CTC) assay was examined, which showed that CS-C increased the rate of incapacitation F pattern spermatozoa converted to capacitation B pattern sperm cell in concentration-dependent manner and mostly increased capacitation B pattern sperm cell and decreased acrosome reaction AR pattern sperm cell in 1mg/ml concentration. When sperm was incubated for 1, 2 and 4h in fertilization medium containing 1mg/ml CS-C, it showed that the capacitated B pattern sperm cell was significantly (p<0.01) increased and the AR pattern sperm cell was significantly decreased at each time point in the presence than in the absence of CS-C. For identifying the validity of CS-C in sperm capacitation, sperm-oocyte was inseminated in fertilization medium containing CS-C (0-2mg/ml) and the rate of fertilized oocytes was examined, which showed that the penetration rates significantly (p<0.05) increased from 0.5 to 1.0mg/ml concentrations (87.4-96.3%) compared with control (74.9%). For identifying the universality of CS-C in sperm capacitation, four different semens (boar S-484, S-454, D-815 and D-748) were incubated in fertilization medium containing CS-C (1mg/ml) for 2h, respectively, which showed that CS-C increased the rate of capacitation B pattern sperm cell and decreased acrosome reaction AR pattern sperm cell in each semen. And it showed that CS-C yielded a higher promote effect (93.9%, 83.9%, 60.7% and 44.9%, respectively) on sperm penetration compared to unaddition control (63.4%, 22.0%, 3.3% and 3.3%, respectively). Sperm-oocyte binding analysis showed that CS-C increased the number of sperm bound to oocyte compared unaddition control in each semen. These results suggested that CS-C is the efficient factor on sperm capacitation in pigs, CS-C may promote sperm from the incapacitated to capacitated state and sequentially prevent sperm from spontaneous acrosome reaction, and thus facilitate the sperm-zona binding and sperm penetration to oocyte. 相似文献
94.
A new approach to directed gene evolution by recombined extension on truncated templates (RETT) 总被引:2,自引:0,他引:2
Si Hyoung Lee Eon Jung Ryu Min Jung Kang Eun-Sun Wang Zhe Piao Yeon Jin Choi Kyung Hwa Jung John Y. J. Jeon Yong Chul Shin 《Journal of Molecular Catalysis .B, Enzymatic》2003,26(3-6):119-129
We describe a new approach to in vitro DNA recombination technique termed recombined extension on truncated templates (RETT). RETT generates random recombinant gene library by template-switching of unidirectionally growing polynucleotides from primers in the presence of unidirectional single-stranded DNA fragments used as templates. RETT was applied to the recombination of two homologous chitinase genes from S. marcescens ATCC 21074 and S. liquefaciens GM1403. When the shuffled genes were examined by restriction mapping and sequence analysis, it was found that chimeric genes were produced at a high frequency (more than 70%) between two chitinase genes with 83% of sequence identity. The number of crossovers within each chimeric gene ranged from one to four, and the recombination points were randomly distributed along entire DNA sequence. We also applied RETT to directed evolution of a chitinase variant for enhancing thermostability. Chimeric chitinases that were more thermostable than the parental enzyme were successfully obtained by RETT-based recombination. 相似文献
95.
Genetic engineering of lactic acid bacteria (LAB) requires a reliable gene expression system. Especially, a stable promoter
is an important genetic element to induce gene expression in such a system. We report on a novel tuf promoter (Ptuf) of Lactococcus lactis subsp. lactis IL1403 that was screened and selected through analysis of previously published microarray data. Ptuf activity was examined and compared with three other known lactococcal promoters (PdnaJ, PpfkA, and Pusp45) using different bacteria as expression hosts. Each promoter was, respectively, fused to the promoterless and modified bmpB gene as a reporter, and we estimated promoter activity through BmpB expression. All promoters were active in IL1403, and
Ptuf activity was strongest among them. The activity of each promoter differed by host bacteria (Lactobacillus plantarum Lb25, Lactobacillus reuteri ATCC23272, and Escherichia coli Top10F’). Ptuf had the highest activity in IL1403 when growth reached late log phase. The activity of each promoter correlated with the
expression of each cognate gene in the microarray data (R
2 = 0.7186, P = 0.06968). This study revealed that novel food-grade promoters such as IL1403 Ptuf can be selected from microarray data for food-grade microorganisms and Ptuf can be used to develop a reliable gene expression system in L. lactis. 相似文献
96.
Hui Feng Peng Wei Zhong-Yun Piao Zhi-Yong Liu Cheng-Yu Li Yu-Gang Wang Rui-Qin Ji Shu-Juan Ji Ting Zou Su-Ryun Choi Yong-Pyo Lim 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(2):333-339
The genic multiple-allele inherited male-sterile gene Ms in Chinese cabbage (Brassica rapa L.) was identified as a spontaneous mutation. Applying this gene to hybrid seed production, several B. rapa cultivars have been successfully bred in China. A BC1 population (244 plants) was constructed for mapping the Ms gene. Screening 268 simple sequence repeat (SSR) markers which cover the entire genome of Chinese cabbage was performed with
bulked segregant analysis (BSA). On the basis of linkage analysis, the Ms gene was located on linkage group R07. In addition, through the amplified fragment length polymorphism (AFLP) and the sequence-characterized
amplified region (SCAR) techniques combining BSA, two SCAR markers which were converted from corresponding AFLP markers flanked
the Ms gene. Finally, a genetic map of the Ms gene was constructed covering a total interval of 9.0 cM. Two SCAR markers, syau_scr01 and syau_scr04, flanked the Ms gene at distances of 0.8 and 2.5 cM, respectively. All the SSR markers (cnu_m273, cnu_m030, cnu_m295, and syau_m13) were
mapped on the same side of the gene as syau_scr04, the nearest one of which, syau_m13, was mapped at a distance of 3.3 cM.
These SSR and SCAR markers may be useful in marker-assisted selection and map-based cloning.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
97.
98.
Defining Developmental Potency and Cell Lineage Trajectories by Expression Profiling of Differentiating Mouse Embryonic Stem Cells 总被引:1,自引:0,他引:1 下载免费PDF全文
99.
100.
Jin Woong Chung Zheng-Hao Piao Suk Ran Yoon Mi Sun Kim Mira Jeong Suk Hyung Lee Jeong Ki Min Jae Wha Kim You-Hee Cho Jin Chul Kim Jeong Keun Ahn Kyoon Eon Kim Inpyo Choi 《PLoS pathogens》2009,5(8)
Pseudomonas aeruginosa (PA) is an opportunistic pathogen that causes the relapse of illness in immunocompromised patients, leading to prolonged hospitalization, increased medical expense, and death. In this report, we show that PA invades natural killer (NK) cells and induces phagocytosis-induced cell death (PICD) of lymphocytes. In vivo tumor metastasis was augmented by PA infection, with a significant reduction in NK cell number. Adoptive transfer of NK cells mitigated PA-induced metastasis. Internalization of PA into NK cells was observed by transmission electron microscopy. In addition, PA invaded NK cells via phosphoinositide 3-kinase (PI3K) activation, and the phagocytic event led to caspase 9-dependent apoptosis of NK cells. PA-mediated NK cell apoptosis was dependent on activation of mitogen-activated protein (MAP) kinase and the generation of reactive oxygen species (ROS). These data suggest that the phagocytosis of PA by NK cells is a critical event that affects the relapse of diseases in immunocompromised patients, such as those with cancer, and provides important insights into the interactions between PA and NK cells. 相似文献