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   6218篇
  免费   956篇
  国内免费   237篇
  2024年   36篇
  2023年   198篇
  2022年   211篇
  2021年   457篇
  2020年   441篇
  2019年   622篇
  2018年   367篇
  2017年   271篇
  2016年   251篇
  2015年   300篇
  2014年   473篇
  2013年   532篇
  2012年   296篇
  2011年   298篇
  2010年   215篇
  2009年   211篇
  2008年   220篇
  2007年   184篇
  2006年   194篇
  2005年   171篇
  2004年   141篇
  2003年   122篇
  2002年   142篇
  2001年   77篇
  2000年   76篇
  1999年   98篇
  1998年   89篇
  1997年   71篇
  1996年   67篇
  1995年   57篇
  1994年   62篇
  1993年   37篇
  1992年   53篇
  1991年   48篇
  1990年   44篇
  1989年   50篇
  1988年   34篇
  1987年   26篇
  1986年   14篇
  1985年   28篇
  1984年   27篇
  1983年   17篇
  1982年   10篇
  1981年   19篇
  1980年   13篇
  1979年   12篇
  1978年   14篇
  1977年   6篇
  1975年   3篇
  1972年   2篇
排序方式: 共有7411条查询结果,搜索用时 453 毫秒
981.
982.
Circular RNA is a newly discovered member of non-coding RNA (ncRNA) and regulates the target gene by acting as a micro-RNA sponge. It plays vital roles in various diseases. However, the functions of circular RNA in non-small cell lung cancer (NSCLC) remain still unclear. Our data showed that circ-WHSC1 was highly expressed in NSCLC cells and tissues. Both in vitro and in vivo experiments showed that circ-WHSC1 promoted NSCLC proliferation. circ-WHSC1 also promoted the migration and invasion of lung cancer cells. Through bioinformatic analysis and functional experiments, we showed that circ-WHSC1 could act as a sponge for micro-RNA-7 (miR-7) and regulate the expression of TAB2 (TGF-beta activated kinase one binding protein two). Inhibition of the circ-WHSC1/miR-7/TAB2 pathway could effectively attenuate lung cancer progression. In summary, this study confirmed the existence and oncogenic function of circ-WHSC1 in NSCLC. The research suggests that the circ-WHSC1/miR-7/TAB2 axis might be a potential target for NSCLC therapy.  相似文献   
983.
984.
Our previous research has found that miRNA-22 can inhibit the occurrence of pyroptosis by targeting GSDMD and decrease the production and release of inflammatory factors. In consideration of the therapeutic effects of mesenchymal stem cells (MSCs), MSCs-EV were loaded with miRNA-22 (EV-miRNA-22) to investigate the inhibitory effect of EV-miRNA-22 on the inflammatory response in SCI in rats in this study. LPS/Nigericin (LPS/NG) was used to induce pyroptosis in rat microglia in vitro. Propidium iodide (PI) staining was performed to observe cell permeability, lactate dehydrogenase (LDH) release assay was adopted to detect cytotoxicity, flow cytometry was conducted to detect pyroptosis level, immunofluorescence (IF) staining was utilized to observe the expression level of GSDMD (a key protein of pyroptosis), Western blot was performed to detect the expression of key proteins. For animal experiments, the T10 spinal cord of rats was clamped by aneurysm clip to construct the SCI model. BBB score, somatosensory evoked potential (SEP) and motor evoked potential (MEP) were performed to detect nerve function. HE staining and Nissl staining were used to detect spinal cord histopathology and nerve cell damage. EV-miRNA-22 could inhibit the occurrence of pyroptosis in microglia, suppress the cell membrane pore opening, and inhibit the release of inflammatory factors and the expression of GSDMD. In addition, EV-miRNA-22 showed higher pyroptosis-inhibiting ability than EV. Consequently, EV-miRNA-22 could inhibit the nerve function injury after SCI in rats, inhibit the level of inflammatory factors in the tissue and the activation of microglia. In this study, we found that miRNA-22-loaded MSCs-EV (EV-miRNA-22) could cooperate with EV to inhibit inflammatory response and nerve function repair after SCI.  相似文献   
985.
986.
Inherited cases of Alzheimer's disease (AD) comprise only a very small proportion of the total. The remainder are of unknown etiopathogenesis, but they are very probably multifactorial in origin. This article describes studies on four possible factors: aluminum; viruses—in particular, herpes simplex type I virus (HSV1); defective DNA repair; and head trauma. Specific problems associated with aluminum, such as inadvertent contamination and its insolubility, have led to some controversy over its usage. Nonetheless, the effects of aluminum on animals and neuronal cells in culture have been studied intensively. Changes in protein structure and location in the cell are described, including the finding in this laboratory of a change in τ resembling that in AD neurofibrillary tangles, and also the lack of appreciable binding of aluminum to DNA. As for HSV1, there has previously been uncertainty about whether HSV1 DNA is present in human brain. Work in this laboratory using polymerase chain reaction has shown that HSV1 DNA is present in many normal aged brains and AD brains, but is absent in brains from younger people. Studies on DNA damage and repair in AD and normal cells are described, and finally, the possible involvement of head trauma is discussed.  相似文献   
987.
988.
Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As such, primary or ''neuronal-like'' cell culture systems are commonly utilized. While these systems are relatively easy to work with, and are useful model systems in which various functional outcomes (such as cell death) can be readily quantified, the examined outcomes and pathways in cultured immature neurons (such as excitotoxicity-mediated cell death pathways) are not necessarily the same as those observed in mature brain, or in intact tissue. Therefore, there is the need to develop models in which cellular mechanisms in mature neural tissue can be examined. We have developed an in vitro technique that can be used to investigate a variety of molecular pathways in intact nervous tissue. The technique described herein utilizes rat cortical tissue, but this technique can be adapted to use tissue from a variety of species (such as mouse, rabbit, guinea pig, and chicken) or brain regions (for example, hippocampus, striatum, etc.). Additionally, a variety of stimulations/treatments can be used (for example, excitotoxic, administration of inhibitors, etc.). In conclusion, the brain slice model described herein can be used to examine a variety of molecular mechanisms involved in excitotoxicity-mediated brain injury.  相似文献   
989.
A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to laser heating. The temperature distribution of the skin is modeled by the bioheat transfer equation, and the influence of laser heating is expressed as a source term where the strength of the source is a product of a Gaussian shaped incident irradiance, an exponentially shaped axial attenuation, and a time function. The water evaporation and diffusion is included in the model by adding two terms regarding the heat loss due to the evaporation and diffusion, where the rate of water evaporation is determined based on the theory of laminar boundary layer. Cryogen spray cooling (CSC) in laser therapy is studied, as well as its effect on the skin thermal response. The time-dependent equation is discretized using the finite difference method with the Crank–Nicholson scheme and the stability of the numerical method is analyzed. The large sparse linear system resulted from discretizing the governing partial differential equation is solved by a GMRES solver and the expected simulation results are obtained.  相似文献   
990.
Experiments were performed with human plasma irradiated in vitro or in vivo in order to evaluate the extent to which clastogenic factors might disturb the adaptive response to DNA-damaging factors currently studied in our laboratory. The studies were carried out with plasma isolated from whole blood given 4 Gy of X-rays in vitro and with plasma from people receiving local radiotherapy at a total dose of about 60 Gy gamma rays. Addition of irradiated plasma to culture medium did not result in a statistically significant increase in structural aberrations in chromosomes of non-irradiated normal blood.  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