首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5166篇
  免费   431篇
  国内免费   293篇
  5890篇
  2024年   11篇
  2023年   48篇
  2022年   126篇
  2021年   216篇
  2020年   133篇
  2019年   185篇
  2018年   212篇
  2017年   140篇
  2016年   237篇
  2015年   329篇
  2014年   378篇
  2013年   336篇
  2012年   464篇
  2011年   434篇
  2010年   264篇
  2009年   252篇
  2008年   273篇
  2007年   255篇
  2006年   218篇
  2005年   202篇
  2004年   184篇
  2003年   164篇
  2002年   169篇
  2001年   100篇
  2000年   68篇
  1999年   70篇
  1998年   60篇
  1997年   42篇
  1996年   40篇
  1995年   35篇
  1994年   29篇
  1993年   23篇
  1992年   21篇
  1991年   27篇
  1990年   23篇
  1989年   20篇
  1988年   9篇
  1987年   9篇
  1986年   14篇
  1985年   16篇
  1983年   9篇
  1982年   6篇
  1981年   10篇
  1980年   3篇
  1979年   5篇
  1978年   3篇
  1976年   2篇
  1972年   5篇
  1971年   3篇
  1969年   3篇
排序方式: 共有5890条查询结果,搜索用时 0 毫秒
11.
12.
Despite the fact that long noncoding RNAs (lncRNAs) play roles in almost all biological processes, little is known about their biological function in the endometrium during the formation of endometrial receptivity. In this study, a comprehensive analysis of lncRNAs in goat endometrial tissues on Day 5 (prereceptive endometrium, PE) and Day 15 (receptive endometrium, RE) of pregnancy was performed by using RNA-Seq. As a result, 668 differentially expressed lncRNAs (DELs) were found between the PE and RE. Further study showed that lncRNA882, regulated by estrogen (E2) and progestin (P4), could act as competing endogenous RNAs (ceRNAs) for miR-15b, which inhibited the expression of transforming growth factor-b-activated kinase 1 binding protein 3 (TAB3) and then indirectly regulated the level of leukemia inhibitory factor (LIF). This was helpful for the formation of endometrial receptivity in dairy goats. In conclusion, we elucidated the endometrium lncRNA profiles of PE and RE in dairy goats; lncRNA882 acted as a ceRNA for miR-15b and then indirectly regulated the level of LIF in goat endometrial epithelium cells. Thus, this study helped us to better understand the molecular regulation of endometrial receptivity in dairy goats.  相似文献   
13.
Previously, we reported a method to generate and validate cell cycle‐synchronized cultures of multiple mammalian suspension cell lines under near‐physiological conditions. This method was applied to elucidate the putative interdependencies of the cell cycle and recombinant protein expression in the human producer cell line HEK293s using Lipofectamine 2000 and the reporter plasmid pcDNA3.3 enhanced green fluorescent protein, destabilized using PEST sequence. A population‐resolved modeling approach was applied to quantitatively assess putative variations of cell cycle dependent expression rates based on the obtained experimental data. We could not confirm results published earlier by other groups, based on nonphysiological synchronization attempts, reporting transfection efficiency being strongly dependent on the cell cycle phase at transfection time point. On the other hand, it is demonstrated that transfection and protein expression distort the progression of the cell cycle.  相似文献   
14.
He W  Zhao Y  Zhang C  An L  Hu Z  Liu Y  Han L  Bi L  Xie Z  Xue P  Yang F  Hang H 《Nucleic acids research》2008,36(20):6406-6417
Rad9 is conserved from yeast to humans and plays roles in DNA repair (homologous recombination repair, and base-pair excision repair) and cell cycle checkpoint controls. It has not previously been reported whether Rad9 is involved in DNA mismatch repair (MMR). In this study, we have demonstrated that both human and mouse Rad9 interacts physically with the MMR protein MLH1. Disruption of the interaction by a single-point mutation in Rad9 leads to significantly reduced MMR activity. This disruption does not affect S/M checkpoint control and the first round of G2/M checkpoint control, nor does it alter cell sensitivity to UV light, gamma rays or hydroxyurea. Our data indicate that Rad9 is an important factor in MMR and carries out its MMR function specifically through interaction with MLH1.  相似文献   
15.
16.
Aedes aegypti and Culex pipiens s.l. (Linnaeus, 1762 and 1758, respectively) (Diptera: Culicidae) are important vectors of diseases to humans and a growing public health concern. In order to contribute to the control of mosquito vectors by low environmental impact approaches we assessed the susceptibility of natural populations of container-breeding mosquitoes to triflumuron, an insect growth regulator, in temperate Argentina. A field trial was conducted to evaluate the efficacy of two doses (0.5 ppm and 1 ppm) of triflumuron (SC 48%) against natural populations of Ae. aegypti and Culex spp. immatures in flower vases of four cemeteries. The results demonstrated the susceptibility of both target mosquitoes to triflumuron in field conditions. For Ae. aegypti, dose-dependent reductions were achieved in the presence of pupae and the percentage of water-holding containers harbouring L3–4 and/or pupae, whereas the larvae abundance was equally reduced for both doses. For Culex spp., similar levels of reduction of larvae abundance and pupae presence were achieved with both doses. Significant effects on the response variables measured were recorded up to six to eight weeks post-intervention. Bimonthly applying 1 ppm triflumuron in the context of an integrated mosquito management should achieve a lasting control of Ae. aegypti and Culex spp. in small artificial containers with minimal environmental impacts.  相似文献   
17.
The traditional view holds that peroxisomes are autonomous organelles multiplying by growth and division. More recently, new observations have challenged this concept. Herein, we present evidence supporting the involvement of the endoplasmic reticulum (ER) in peroxisome formation by electron microscopy, immunocytochemistry and three-dimensional image reconstruction of peroxisomes and associated compartments in mouse dendritic cells. We found the peroxisomal membrane protein Pex13p and the ATP-binding cassette transporter protein PMP70 present in specialized subdomains of the ER that were continuous with a peroxisomal reticulum from which mature peroxisomes arose. The matrix proteins catalase and thiolase were only detectable in the reticula and peroxisomes. Our results suggest the existence of a maturation pathway from the ER to peroxisomes and implicate the ER as a major source from which the peroxisomal membrane is derived.  相似文献   
18.
目的探讨猪冠状动脉前降支(LAD)结扎百分位点和心梗体积、左室射血分数的关系,以期指导研究者能够根据急性心肌梗死模型的心功能要求选择合适的LAD结扎百分位点。方法将47只小型猪开胸结扎心脏LAD中远段约30%~75%的不同百分位点,分别于术前、术后1 h心脏超声检查左室射血分数(LVEF),术后3 d进行常规冠状动脉造影,4周处死测量前降支结扎位点和梗死体积,最后用简单直线回归模型分析LAD结扎百分位点和心梗体积、左室射血分数回归方程和相关系数。结果47例动物手术过程中死亡8只,剩余39只存活动物冠状动脉造影均显示LAD中远段结扎部位处完全闭塞,表明手术成功。LAD结扎百分位点和术后1 h LVEF、术后1 hLVEF下降值、梗死心肌体积均明显相关(相关系数r分别为0.87、0.78和0.90,P均<0.001),其回归方程分别为:术后LVEF(%)=65.88-0.55x结扎百分位点;术后LVEF下降值(%)=0.12 0.59x结扎百分位点;心肌梗死体积(%)=0.53x结扎百分位点-5.43。结论猪LAD结扎百分位点和术后左室功能、梗死心肌体积均存在显著的相关性,可根据实验目的和对心功能的要求选择合适的结扎百分位点。  相似文献   
19.
Ovarian cancer is the leading cause of death from all gynecological cancers and conventional therapies such as surgery, chemotherapy, and radiotherapy usually fail to control advanced stages of the disease. Thus, there is an urgent need for alternative and innovative therapeutic options. We reason that cancer gene therapy using a vector capable of specifically delivering an enzyme-encoding gene to ovarian cancer cells will allow the cancer cell to metabolize a harmless prodrug into a potent cytotoxin, which will lead to therapeutic effects. In the current study, we explore the use of a human papillomavirus (HPV) pseudovirion to deliver a herpes simplex virus thymidine kinase (HSV-tk) gene to ovarian tumor cells. We found that the HPV-16 pseudovirion was able to preferentially infect murine and human ovarian tumor cells when administered intraperitoneally. Furthermore, intraperitoneal injection of HPV-16 pseudovirions carrying the HSV-tk gene followed by treatment with ganciclovir led to significant therapeutic anti-tumor effects in murine ovarian cancer-bearing mice. Our data suggest that HPV pseudovirion may serve as a potential delivery vehicle for ovarian cancer gene therapy.  相似文献   
20.
In this study, comparative proteomics was used to investigate the interaction of Spodoptera exigua and Arabidopsis thaliana. By using 2-D electrophoresis of differentially expressed proteins, combined with high-throughput matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF/TOF MS, the changes in the abundance of proteins induced by insect feeding were studied in A. thaliana. More than 1,100 protein spots were reproducibly detected on each gel. The intensities of 30 protein spots in particular changed significantly, showing differences in volume of at least twofold. Among these, 17 protein spots were upregulated, and 13 were downregulated following an 8-h insect feeding period. Nineteen insect-feeding-responsive proteins were identified, all of which were involved in metabolic regulation, binding functions or cofactor requirement of protein, cell rescue, and defense and virulence, as assessed by Munich Information Center for Protein Sequences function category. About 50% of these were involved in metabolism, including transketolase, S-adenosylmethionine synthase 3, 2,3-biphosphoglycerate-independent phosphoglycerate mutase, beta-ureidopropionase, GDP-d-mannose 3′,5′-epimerase, and fatty acid synthase. The identification of insect-feeding-responsive proteins on Arabidopsis provides not only new insights into insect stress but also a good start for further investigation of their functions. Understanding how the plant responses to insects in the proteomic level will provide tools for a better management of insect pest in the field.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号