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   14924篇
  免费   1158篇
  国内免费   1091篇
  2024年   18篇
  2023年   149篇
  2022年   408篇
  2021年   814篇
  2020年   485篇
  2019年   595篇
  2018年   625篇
  2017年   523篇
  2016年   619篇
  2015年   894篇
  2014年   1069篇
  2013年   1201篇
  2012年   1400篇
  2011年   1251篇
  2010年   776篇
  2009年   685篇
  2008年   751篇
  2007年   627篇
  2006年   605篇
  2005年   489篇
  2004年   431篇
  2003年   332篇
  2002年   344篇
  2001年   312篇
  2000年   254篇
  1999年   249篇
  1998年   165篇
  1997年   131篇
  1996年   134篇
  1995年   126篇
  1994年   138篇
  1993年   92篇
  1992年   96篇
  1991年   70篇
  1990年   66篇
  1989年   58篇
  1988年   56篇
  1987年   31篇
  1986年   33篇
  1985年   19篇
  1984年   23篇
  1983年   12篇
  1982年   8篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1976年   1篇
  1975年   1篇
  1933年   1篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
191.
Biomechanics and Modeling in Mechanobiology - The aim of this study was to evaluate the effectiveness of various head injury criteria and associated risk functions in prediction of vulnerable road...  相似文献   
192.
193.
Ovarian cancer (OC) is ranked the first among the cancers threatening women's health. It attracts tremendous attention of cancer researchers because of its extremely high mortality rate. Recent studies have indicated that traditional herbal medicines (THMs) can play a pivotal role in cancer prevention and treatment. THMs are gaining popularity as a source of anti‐cancer agents. The plant of Balanophora polyandra, which has been used as a traditional herbal medicine, has been known for exhibiting potential haemostatic, analgesic, anti‐inflammatory and anti‐cancer properties. However, few studies on inhibitory effect of B. polyandra on OC have been performed. In the present study, we found that B. polyandra polysaccharides (BPP) induced cell cycle arrest at S phase, triggered apoptosis and inhibited migration and invasion of OC cells. Furthermore, we also found that there was a potential and close relationship between BPP and P53‐mediated pathway. Overall, these findings suggest that BPP can be a potential therapeutic agent for the treatment of OC.  相似文献   
194.
195.
Histone deacetylases (HDACs) belong to a group of epigenetic regulatory enzymes that participate in modulating the acetylation level of histone lysine residues as well as non‐histone proteins, and they play a key role in the regulation of gene expression. HDACs are potential anticancer drug targets highly expressed in various kinds of cancer cells. So far, five small molecules targeting HDACs have been approved for the therapy of cancer, and over 20 inhibitors of HDACs are under different phases of clinical trials. Among them, hydroxamate‐based HDAC inhibitors (HDACis) represent a well‐investigated series of chemical entities. The current review covers the recent progress in the discovery process, form SAHA to hydroxamate HDAC inhibitors with branched CAP region and linear linker. At the same time, the pharmacological and structure‐activity relationship (SAR) studies of the specific derivatives from SAHA and the HDACis with branched CAP region and linear linker are also introduced.  相似文献   
196.
Obesity is positively linked to multiple metabolic complications including renal diseases. Several studies have demonstrated Kruppel‐like factor 4 (KLF4) participated in renal dysfunction and structural disorders in acute kidney injuries, but whether it affected the process of chronic kidney diseases was unknown. Therefore, present study was to disclose the role of renal KLF4 in dietary‐induced renal injuries and underlying mechanisms in obesity. Through utilizing high‐fat diet‐fed mice and human renal biopsies, we provided the physiological roles of KLF4 in protecting against obesity‐related nephropathy. Decreased levels of renal KLF4 were positively correlated with dietary‐induced renal dysfunction, including increased levels of creatinine and blood urea nitrogen. Overexpression of renal KLF4 suppressed inflammatory response in palmitic acid‐treated mouse endothelial cells. Furthermore, overexpressed KLF4 also attenuated dietary‐induced renal functional disorders, abnormal structural remodelling and inflammation. Mechanistically, KLF4 maintained renal mitochondrial biogenesis and activities to combat obesity‐induced mitochondrial dysfunction. In clinical renal biopsies and plasma, the renal Klf4 level was negatively associated with circulating levels of creatinine but positively associated with renal creatinine clearance. In conclusions, the present findings firstly supported that renal KLF4 played an important role in combating obesity‐related nephropathy, and KLF4/mitochondrial function partially determined the energy homeostasis in chronic kidney diseases.  相似文献   
197.
The heterogeneity in prognoses and chemotherapeutic responses of colon cancer patients with similar clinical features emphasized the necessity for new biomarkers that help to improve the survival prediction and tailor therapies more rationally and precisely. In the present study, we established a s troma-related l ncRNA s ignature (SLS) based on 52 lncRNAs to comprehensively predict clinical outcome. The SLS model could not only distinguish patients with different recurrence and mortality risks through univariate analysis, but also served as an independent factor for relapse-free and overall survival. Compared with the conventionally used TNM stage system, the SLS model clearly possessed higher predictive accuracy. Moreover, the SLS model also effectively screened chemotherapy-responsive patients, as only patients in the low-SLS group could benefit from adjuvant chemotherapy. The following cell infiltration and competing endogenous RNA (ceRNA) network functional analyses further confirmed the association between the SLS model and stromal activation-related biological processes. Additionally, this study also identified three phenotypically distinct colon cancer subtypes that varied in clinical outcome and chemotherapy benefits. In conclusion, our SLS model may be a significant determinant of survival and chemotherapeutic decision-making in colon cancer and may have a strong clinical transformation value.  相似文献   
198.
AMP‐activated protein kinase (AMPK) is an intracellular sensor of energy homoeostasis that is activated under energy stress and suppressed in energy surplus. AMPK activation leads to inhibition of anabolic processes that consume ATP. Osteogenic differentiation is a process that highly demands ATP during which AMPK is inhibited. The bone morphogenetic proteins (BMPs) signalling pathway plays an essential role in osteogenic differentiation. The present study examines the inhibitory effect of metformin on BMP signalling, osteogenic differentiation and trauma‐induced heterotopic ossification. Our results showed that metformin inhibited Smad1/5 phosphorylation induced by BMP6 in osteoblast MC3T3‐E1 cells, concurrent with up‐regulation of Smad6, and this effect was attenuated by knockdown of Smad6. Furthermore, we found that metformin suppressed ALP activity and mineralization of the cells, an event that was attenuated by the dominant negative mutant of AMPK and mimicked by its constitutively active mutant. Finally, administration of metformin prevented the trauma‐induced heterotopic ossification in mice. In conjuncture, AMPK activity and Smad6 and Smurf1 expression were enhanced by metformin treatment in the muscle of injured area, concurrently with the reduction of ALK2. Collectively, our study suggests that metformin prevents heterotopic ossification via activation of AMPK and subsequent up‐regulation of Smad6. Therefore, metformin could be a potential therapeutic drug for heterotopic ossification induced by traumatic injury.  相似文献   
199.
Epidemiological studies have found that diabetes and cognitive dysfunction are closely related. Quercetin has been certified with the effect on improving diabetes mellitus (DM) and cognitive impairment. However, the effect and related mechanism of quercetin on diabetic encephalopathy (DE) are still ambiguous. In this study, we used the db/db mice (diabetic model) to discover whether quercetin could improve DE through the Sirtuin1/NLRP3 (NOD-, LRR- and pyrin domain-containing 3) pathway. Behavioural results (Morris water maze and new object recognition tests) showed that quercetin (70 mg/kg) improved the learning and memory. Furthermore, quercetin alleviated insulin resistance and the level of fasting blood glucose. Besides, Western blot analysis also showed that quercetin increased the protein expressions of nerve- and synapse-related protein, including postsynapticdensity 93 (PSD93), postsynapticdensity 95 (PSD95), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the brain of db/db mice. Quercetin also increased the protein expression of SIRT1 and decreased the expression of NLRP3 inflammation-related proteins, including NLRP3, the adaptor protein ASC and cleaved Caspase-1, the pro-inflammatory cytokines IL-1β and IL-18. In conclusion, the present results indicate that the SIRT1/NLRP3 pathway may be a crucial mechanism for the neuroprotective effect of quercetin against DE.  相似文献   
200.
Chronic pancreatitis (CP), characterized by pancreatic fibrosis, is a recurrent, progressive and irreversible disease. Activation of the pancreatic stellate cells (PSCs) is considered a core event in pancreatic fibrosis. In this study, we investigated the role of hydrogen peroxide‐inducible clone‐5 (Hic‐5) in CP. Analysis of the human pancreatic tissue samples revealed that Hic‐5 was overexpressed in patients with CP and was extremely low in healthy pancreas. Hic‐5 was significant up‐regulated in the activated primary PSCs independently from transforming growth factor beta stimulation. CP induced by cerulein injection was ameliorated in Hic‐5 knockout (KO) mice, as shown by staining of tissue level. Simultaneously, the activation ability of the primary PSCs from Hic‐5 KO mice was significantly attenuated. We also found that the Hic‐5 up‐regulation by cerulein activated the NF‐κB (p65)/IL‐6 signalling pathway and regulated the downstream extracellular matrix (ECM) genes such as α‐SMA and Col1a1. Therefore, we determined whether suppressing NF‐κB/p65 alleviated CP by treating mice with the NF‐κB/p65 inhibitor triptolide in the cerulein‐induced CP model and found that pancreatic fibrosis was alleviated by NF‐κB/p65 inhibition. These findings provide evidence for Hic‐5 as a therapeutic target that plays a crucial role in regulating PSCs activation and pancreatic fibrosis.  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