全文获取类型
收费全文 | 11657篇 |
免费 | 283篇 |
国内免费 | 355篇 |
出版年
2023年 | 119篇 |
2022年 | 141篇 |
2021年 | 256篇 |
2020年 | 271篇 |
2019年 | 449篇 |
2018年 | 270篇 |
2017年 | 164篇 |
2016年 | 114篇 |
2015年 | 125篇 |
2014年 | 444篇 |
2013年 | 709篇 |
2012年 | 328篇 |
2011年 | 597篇 |
2010年 | 462篇 |
2009年 | 553篇 |
2008年 | 571篇 |
2007年 | 598篇 |
2006年 | 504篇 |
2005年 | 461篇 |
2004年 | 352篇 |
2003年 | 289篇 |
2002年 | 235篇 |
2001年 | 152篇 |
2000年 | 170篇 |
1999年 | 167篇 |
1998年 | 166篇 |
1997年 | 141篇 |
1996年 | 140篇 |
1995年 | 111篇 |
1994年 | 112篇 |
1993年 | 104篇 |
1992年 | 111篇 |
1991年 | 97篇 |
1990年 | 50篇 |
1989年 | 81篇 |
1987年 | 62篇 |
1986年 | 67篇 |
1985年 | 164篇 |
1984年 | 387篇 |
1983年 | 292篇 |
1982年 | 292篇 |
1981年 | 237篇 |
1980年 | 176篇 |
1979年 | 181篇 |
1978年 | 135篇 |
1977年 | 129篇 |
1976年 | 125篇 |
1975年 | 110篇 |
1974年 | 91篇 |
1973年 | 98篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
991.
Tuula Salo Marilena Vered Ibrahim O. Bello Pia Nyberg Carolina Cavalcante Bitu Ayelet Zlotogorski Hurvitz Dan Dayan 《Experimental cell research》2014
The research on oral cancer has focused mainly on the cancer cells, their genetic changes and consequent phenotypic modifications. However, it is increasingly clear that the tumor microenvironment (TME) has been shown to be in a dynamic state of inter-relations with the cancer cells. The TME contains a variety of components including the non-cancerous cells (i.e., immune cells, resident fibroblasts and angiogenic vascular cells) and the ECM milieu [including fibers (mainly collagen and fibronectin) and soluble factors (i.e., enzymes, growth factors, cytokines and chemokines)]. Thus, it is currently assumed that TME is considered a part of the cancerous tissue and the functionality of its key components constitutes the setting on which the hallmarks of the cancer cells can evolve. Therefore, in terms of controlling a malignancy, one should control the growth, invasion and spread of the cancer cells through modifications in the TME components. This mini review focuses on the TME as a diagnostic approach and reports the recent insights into the role of different TME key components [such as carcinoma-associated fibroblasts (CAFs) and inflammation (CAI) cells, angiogenesis, stromal matrix molecules and proteases] in the molecular biology of oral carcinoma. Furthermore, the impact of TME components on clinical outcomes and the concomitant need for development of new therapeutic approaches will be discussed. 相似文献
992.
Glioma contains abundant hypoxic regions which provide niches to promote the maintenance and expansion of glioma stem cells (GSCs), which are resistant to conventional therapies and responsible for recurrence. Given the fact that miR-210 plays a vital role in cellular adaption to hypoxia and in stem cell survival and stemness maintenance, strategies correcting the aberrantly expressed miR-210 might open up a new therapeutic avenue to hypoxia GSCs. In the present study, to explore the possibility of miR-210 as an effective therapeutic target to hypoxic GSCs, we employed a lentiviral-mediated anti-sense miR-210 gene transfer technique to knockdown miR-210 expression and analyze phenotypic changes in hypoxic U87s and SHG44s cells. We found that hypoxia led to an increased HIF-2α mRNA expression and miR-210 expression in GSCs. Knockdown of miR-210 decreased neurosphere formation capacity, stem cell marker expression and cell viability, and induced differentiation and G0/G1 arrest in hypoxic GSCs by partially rescued Myc antagonist (MNT) protein expression. Knockdown of MNT could reverse the gene expression changes and the growth inhibition resulting from knockdown of miR-210 in hypoxic GSCs. Moreover, knockdown of miR-210 led to increased apoptotic rate and Caspase-3/7 activity and decreased invasive capacity, reactive oxygen species (ROS) and lactate production and radioresistance in hypoxic GSCs. These findings suggest that miR-210 might be a potential therapeutic target to eliminate GSCs located in hypoxic niches. 相似文献
993.
We purified a fraction that showed NAD+-linked methylglyoxal dehydrogenase activity, directly catalyzing methylglyoxal oxidation to pyruvate, which was significantly increased in glutathione-depleted Candida albicans. It also showed NADH-linked methylglyoxal-reducing activity. The fraction was identified as a NAD+-linked alcohol dehydrogenase (ADH1) through mass spectrometric analyses. In ADH1-disruptants of both the wild type and glutathione-depleted cells, the intracellular methylglyoxal concentration increased significantly; defects in growth, differentiation, and virulence were observed; and G2-phase arrest was induced. 相似文献
994.
Weizhong Chen Liang Zhang Guanqun Zheng Ye Fu Quanjiang Ji Fange Liu Hao Chen Chuan He 《FEBS letters》2014
ALKBH5, a member of AlkB family proteins, has been reported as a mammalian N6-methyladenosine (m6A) RNA demethylase. Here we report the crystal structure of zebrafish ALKBH5 (fALKBH5) with the resolution of 1.65 Å. Structural superimposition shows that fALKBH5 is comprised of a conserved jelly-roll motif. However, it possesses a loop that interferes potential binding of a duplex nucleic acid substrate, suggesting an important role in substrate selection. In addition, several active site residues are different between the two known m6A RNA demethylases, ALKBH5 and FTO, which may result in their slightly different pathways of m6A demethylation. 相似文献
995.
We report sphingolipid-related reorganization of gel-like microdomains in the plasma membrane of living Saccharomyces cerevisiae using trans-Parinaric acid (t-PnA) and 1,6-diphenyl-1,3,5-hexatriene (DPH). Compared to control, the gel-like domains were significantly reduced in the membrane of a sphingolipid-deficient lcb1-100 mutant. The same reduction resulted from sphingolipid depletion by myriocin. The phenotype could be reverted when a myriocin-induced block in sphingolipid biosynthesis was bypassed by exogenous dihydrosphingosine. Lipid order of less-ordered membrane regions decreased with sphingolipid depletion as well, as documented by DPH fluorescence anisotropy. The data indicate that organization of lateral microdomains is an essential physiological role of these structural lipids. 相似文献
996.
Cristina Escoda-Ferran Esther Carrasco Miguel Caballero-Baños Cristina Miró-Julià Mario Martínez-Florensa Marta Consuegra-Fernández Vanesa G. Martínez Fu-Tong Liu Francisco Lozano 《FEBS letters》2014
CD6 is a lymphocyte glycoprotein receptor that physically associates with the antigen-specific receptor complex at the center of the immunological synapse, where it interacts with its ligand CD166/ALCAM. The present work reports the carbohydrate-dependent interaction of CD6 and CD166/ALCAM with Galectin-1 and -3, two well-known soluble mammalian lectins. Both galectins interfered with superantigen-induced T cell proliferation and cell adhesion phenomena mediated by the CD6-CD166/ALCAM pair, while CD6 expression protected cells from galectin-induced apoptosis. The results suggest that interaction of Galectin-1 and -3 with CD6 and CD166/ALCAM might modulate some relevant aspects of T cell physiology. 相似文献
997.
Gokul Swaminathan Daniel Pascual Germaine Rival Renzo Perales-Linares Julio Martin-Garcia Sonia Navas-Martin 《FEBS letters》2014
Despite their differential cell tropisms, HIV-1 and HCV dramatically influence disease progression in coinfected patients. Macrophages are important target cells of HIV-1. We hypothesized that secreted HCV core protein might modulate HIV-1 replication. We demonstrate that HCV core significantly enhances HIV-1 replication in human macrophages by upregulating TNF-α and IL-6 via TLR2-, JNK-, and MEK1/2-dependent pathways. Furthermore, we show that TNF-α and IL-6 secreted from HCV core-treated macrophages reactivates monocytic U1 cells latently infected with HIV-1. Our studies reveal a previously unrecognized role of HCV core by enhancing HIV-1 infection in macrophages. 相似文献
998.
Akira Inoue Naoki Yamamoto Masatsugu Kimura Koji Nishio Hideo Yamane Koichi Nakajima 《FEBS letters》2014
RBM10, originally called S1-1, is a nuclear RNA-binding protein with domains characteristic of RNA processing proteins. It has been reported that RBM10 constitutes spliceosome complexes and that RBM5, a close homologue of RBM10, regulates alternative splicing of apoptosis-related genes, Fas and cFLIP. In this study, we examined whether RBM10 has a regulatory function in splicing similar to RBM5, and determined that it indeed regulates alternative splicing of Fas and Bcl-x genes. RBM10 promotes exon skipping of Fas pre-mRNA as well as selection of an internal 5′-splice site in Bcl-x pre-mRNA. We propose a consensus RBM10-binding sequence at 5′-splice sites of target exons and a mechanistic model of RBM10 action in the alternative splicing. 相似文献
999.
Tatiana S. Cherkesova Tatiana Y. Hargrove M. Cristina Vanrell Igor Ges Sergey A. Usanov Patricia S. Romano Galina I. Lepesheva 《FEBS letters》2014
CYP51 (sterol 14α-demethylase) is an efficient target for clinical and agricultural antifungals and an emerging target for treatment of Chagas disease, the infection that is caused by multiple strains of a protozoan pathogen Trypanosoma cruzi. Here, we analyze CYP51A from the Y strain T. cruzi. In this protein, proline 355, a residue highly conserved across the CYP51 family, is replaced with serine. The purified enzyme retains its catalytic activity, yet has been found less susceptible to inhibition. These biochemical data are consistent with cellular experiments, both in insect and human stages of the pathogen. Comparative structural analysis of CYP51 complexes with VNI and two derivatives suggests that broad-spectrum CYP51 inhibitors are likely to be preferable as antichagasic drug candidates. 相似文献
1000.
Marion Babot Paola Labarbuta Amanda Birch Sara Kee Matthew Fuszard Catherine H. Botting Ilka Wittig Heinrich Heide Alexander Galkin 《BBA》2014
An intriguing feature of mitochondrial complex I from several species is the so-called A/D transition, whereby the idle enzyme spontaneously converts from the active (A) form to the de-active (D) form. The A/D transition plays an important role in tissue response to the lack of oxygen and hypoxic deactivation of the enzyme is one of the key regulatory events that occur in mitochondria during ischaemia. We demonstrate for the first time that the A/D conformational change of complex I does not affect the macromolecular organisation of supercomplexes in vitro as revealed by two types of native electrophoresis. Cysteine 39 of the mitochondrially-encoded ND3 subunit is known to become exposed upon de-activation. Here we show that even if complex I is a constituent of the I + III2 + IV (S1) supercomplex, cysteine 39 is accessible for chemical modification in only the D-form. Using lysine-specific fluorescent labelling and a DIGE-like approach we further identified two new subunits involved in structural rearrangements during the A/D transition: ND1 (MT-ND1) and 39 kDa (NDUFA9). These results clearly show that structural rearrangements during de-activation of complex I include several subunits located at the junction between hydrophilic and hydrophobic domains, in the region of the quinone binding site. De-activation of mitochondrial complex I results in concerted structural rearrangement of membrane subunits which leads to the disruption of the sealed quinone chamber required for catalytic turnover. 相似文献