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   1748篇
  免费   97篇
  国内免费   4篇
  1849篇
  2024年   6篇
  2023年   14篇
  2022年   56篇
  2021年   77篇
  2020年   36篇
  2019年   48篇
  2018年   58篇
  2017年   56篇
  2016年   71篇
  2015年   98篇
  2014年   115篇
  2013年   130篇
  2012年   168篇
  2011年   161篇
  2010年   85篇
  2009年   65篇
  2008年   94篇
  2007年   64篇
  2006年   67篇
  2005年   63篇
  2004年   49篇
  2003年   44篇
  2002年   30篇
  2001年   13篇
  2000年   16篇
  1999年   13篇
  1998年   8篇
  1997年   7篇
  1996年   8篇
  1995年   6篇
  1994年   6篇
  1993年   8篇
  1992年   11篇
  1991年   8篇
  1990年   11篇
  1989年   6篇
  1988年   6篇
  1986年   5篇
  1984年   3篇
  1983年   4篇
  1982年   6篇
  1981年   5篇
  1980年   5篇
  1978年   3篇
  1977年   6篇
  1975年   4篇
  1974年   3篇
  1973年   3篇
  1972年   4篇
  1967年   3篇
排序方式: 共有1849条查询结果,搜索用时 15 毫秒
951.
DRAM, a p53-induced modulator of autophagy, is critical for apoptosis   总被引:23,自引:0,他引:23  
Inactivation of cell death is a major step in tumor development, and p53, a tumor suppressor frequently mutated in cancer, is a critical mediator of cell death. While a role for p53 in apoptosis is well established, direct links to other pathways controlling cell death are unknown. Here we describe DRAM (damage-regulated autophagy modulator), a p53 target gene encoding a lysosomal protein that induces macroautophagy, as an effector of p53-mediated death. We show that p53 induces autophagy in a DRAM-dependent manner and, while overexpression of DRAM alone causes minimal cell death, DRAM is essential for p53-mediated apoptosis. Moreover, analysis of DRAM in primary tumors revealed frequent decreased expression often accompanied by retention of wild-type p53. Collectively therefore, these studies not only report a stress-induced regulator of autophagy but also highlight the relationship of DRAM and autophagy to p53 function and damage-induced programmed cell death.  相似文献   
952.
Analysis of mutants that affect formation and function of the Drosophila larval neuromuscular junction (NMJ) has provided valuable insight into genes required for neuronal branching and synaptic growth. We report that NMJ development in Drosophila requires both the Drosophila ortholog of FNDC3 genes; CG42389 (herein referred to as miles to go; mtgo), and CCT3, which encodes a chaperonin complex subunit. Loss of mtgo function causes late pupal lethality with most animals unable to escape the pupal case, while rare escapers exhibit an ataxic gait and reduced lifespan. NMJs in mtgo mutant larvae have dramatically reduced branching and growth and fewer synaptic boutons compared with control animals. Mutant larvae show normal locomotion but display an abnormal self-righting response and chemosensory deficits that suggest additional functions of mtgo within the nervous system. The pharate lethality in mtgo mutants can be rescued by both low-level pan- and neuronal-, but not muscle-specific expression of a mtgo transgene, supporting a neuronal-intrinsic requirement for mtgo in NMJ development. Mtgo encodes three similar proteins whose domain structure is most closely related to the vertebrate intracellular cytosolic membrane-anchored fibronectin type-III domain-containing protein 3 (FNDC3) protein family. Mtgo physically and genetically interacts with Drosophila CCT3, which encodes a subunit of the TRiC/CCT chaperonin complex required for maturation of actin, tubulin and other substrates. Drosophila larvae heterozygous for a mutation in CCT3 that reduces binding between CCT3 and MTGO also show abnormal NMJ development similar to that observed in mtgo null mutants. Hence, the intracellular FNDC3-ortholog MTGO and CCT3 can form a macromolecular complex, and are both required for NMJ development in Drosophila.  相似文献   
953.
954.
955.
956.
A novel bacterial strain designated as NIO-1008T was isolated from marine sediments sample in Chorao Island India. Cells of the strains were gram positive and non-motile, displayed a rod–coccus life cycle and formed cream to light grey colonies on nutrient agar. Strain NIO-1008T had the chemotaxonomic markers that were consistent for classification in the genus Arthrobacter, i.e. MK-9(H2) (50.3 %), as the major menaquinone, and the minor amount of MK-7 (H2-27.5 %), MK-8 (H4-11.6 %) and MK-8 (H2-10.4 %). anteiso-C15:0, iso-C15:0, iso-C16:0 and C15:0 were the predominant fatty acids. Galactose, glucose and rhamnose are the cell-wall sugars, and DNA G+C content was 61.3 mol%. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that the strains were most similar to Arthrobacter equi IMMIB L-1606T, Arthrobacter chlorophenolicus DSM 12829T, Arthrobacter defluvii KCTC 19209T and Arthrobacter niigatensis CCTCC AB 206012T with 98.5, 98.4, 98.0 and 97.8 %, respectively, and formed a separate lineage. Combined phenotypic data and DNA–DNA hybridization data supported the conclusion that strains NIO-1008T represent a novel species within the genus Arthrobacter, for which the name Arthrobacter enclensis sp. nov., is proposed. The type strain is NIO-1008T = (NCIM 5488T = DSM 25279T).  相似文献   
957.
The 2S albumins are a group of seed storage proteins that have recently attracted considerable attention in the field of allergen science due to their allergenic potential. A new 2S albumin from seeds of Nelumbo nucifera (Nn-2S alb) was purified to electrophoretic homogeneity by the combination of ammonium sulfate fractionation, gel filtration, and ion exchange chromatography. The protein has a molecular mass of about 12 kDa estimated by SDS–PAGE, in good agreement with 12.5 ± 0.01 kDa determined by ESI–MS. Circular dichroism data showed that protein contained about 66% α-helices as estimated by K2D3, indicating that the protein was predominantly helical. The sedimentation coefficient (20,w) of the predicted model was 1.72 ± 0.21 S. The predicted 3-dimensional structure of the Nn-2S alb revealed that the protein has a region of 12 amino acids which largely corresponds to the conserved immuno-dominant epitope of 2S allergens.  相似文献   
958.
Colorectal cancer is (CRC) one of the leading causes of mortality and morbidity. Various genetic factors have been reported to be involved in the development of colorectal cancers including Axin gene. Axin, a major scaffold protein, plays an important role in various bio signaling pathways. We aim to study mutational pattern of Axin gene in colorectal cancer patients of Kashmiri population. The paired tumor and adjacent normal tissue specimens of 50 consecutive patients with CRC were used in our study. The DNA preparations were evaluated for the occurrence of Axin 1 and Axin 2 gene mutations by direct DNA sequencing. We analyzed exon 1a, 1b, 1c, 2, 4, 6, and 10 of Axin 1 and exon 7 of Axin 2. In this study, we found a novel mutation of G>T (GCT>TCT) transversion in exon 7 of Axin 2 gene at codon G695T (p.alanine >?serine) at a frequency of 6% (3/50). In the same exon of Axin 2 gene a single nucleotide polymorphism (SNP) was detected in codon L688L (CCT>CTT) at a frequency of 36% (18/50). In exon 1c of Axin 1 a SNP was detected at codon D726D (GAT>GAC) at a frequency of 62.5% (31/50). Both the SNPs were synonymous hence do not lead to change of amino acid. Although Axin 1 and Axin 2 gene mutations have been found to be involved in the development of colorectal cancers, it seems to be a relatively rare event in Kashmiri population. However, an interesting finding of this study is the novelty of Axin 2 gene mutations which may be a predisposing factor in ethnic Kashmiri population to CRC.  相似文献   
959.
960.
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