全文获取类型
收费全文 | 815篇 |
免费 | 77篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 12篇 |
2020年 | 13篇 |
2019年 | 10篇 |
2018年 | 18篇 |
2017年 | 12篇 |
2016年 | 19篇 |
2015年 | 43篇 |
2014年 | 32篇 |
2013年 | 44篇 |
2012年 | 65篇 |
2011年 | 63篇 |
2010年 | 47篇 |
2009年 | 34篇 |
2008年 | 41篇 |
2007年 | 54篇 |
2006年 | 42篇 |
2005年 | 41篇 |
2004年 | 35篇 |
2003年 | 28篇 |
2002年 | 31篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 10篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1966年 | 6篇 |
1960年 | 2篇 |
排序方式: 共有892条查询结果,搜索用时 46 毫秒
21.
22.
Deepa Geeta Devi Yadav Pooja Chaudhary Mohd Jubair Aalam Dhan Raj Meena Surendra Singh 《Chirality》2020,32(1):64-72
Imidazolidin-4-one is used as a recoverable organocatalyst for the asymmetric Diels-Alder reaction in the presence of catalytic amount of dicationic ionic liquid and trifluoroacetic acid as a co-catalyst. The Diels-Alder reaction between model substrate cyclopentadiene and crotonaldehyde gave the product in 95% conversion and 87% ee of the endo-product. The catalyst was shown better reusability when the 20 mol% of dicationic ionic liquid was used and catalyst was reused upto 5 cycles, conversion remains upto 3 recycles but ee of endo- 9 was slightly droped. 相似文献
23.
24.
Arunagiri Kuha Deva Magendhra Rao Vittal Rangan Arvinden Deepa Ramasamy Krishna Patel Balaiah Meenakumari Priya Ramanathan Shirley Sundersingh Velusami Sridevi Thangarajan Rajkumar Zdenko Herceg Harsha Gowda Samson Mani 《Journal of cellular and molecular medicine》2021,25(8):3912-3921
Breast cancer is a major cause of cancer-related death in women worldwide. Non-coding RNAs are a potential resource to be used as an early diagnostic biomarker for breast cancer. Circular RNAs are a recently identified group of non-coding RNA with a significant role in disease development with potential utility in diagnosis/prognosis in cancer. In this study, we identified 26 differentially expressed circular RNAs associated with early-stage breast cancer. RNA sequencing and two circRNA detection tools (find_circ and DCC) were used to understand the circRNA expression signature in breast cancer. We identified hsa_circ_0006743 (circJMJD1C) and hsa_circ_0002496 (circAPPBP1) to be significantly up-regulated in early-stage breast cancer tissues. Co-expression analysis identified four pairs of circRNA-miRNA (hsa_circ_0023990 : hsa-miR-548b-3p, hsa_circ_0016601 : hsa_miR-1246, hsa_circ_0001946 : hsa-miR-1299 and hsa_circ_0000117:hsa-miR-502-5p) having potential interaction. The miRNA target prediction and network analysis revealed mRNA possibly regulated by circRNAs. We have thus identified circRNAs of diagnostic implications in breast cancer and also observed circRNA-miRNA interaction which could be involved in breast cancer development. 相似文献
25.
Marla J. Steinbeck Natalie Chernets Jun Zhang Deepa S. Kurpad Gregory Fridman Alexander Fridman Theresa A. Freeman 《PloS one》2013,8(12)
Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma) to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS) and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide) and dihydrorhodamine (peroxide) were used to assess onset and duration after NT-plasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. These increases were sustained for one hour but returned to control levels by 24 hr. Using the same treatment conditions, osteogenic differentiation by NT-plasma was assessed and compared to peroxide or osteogenic media containing β-glycerolphosphate. Although both NT-plasma and peroxide induced differentiation-specific gene expression, neither was as effective as the osteogenic media. However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS signaling to enhance differentiation, and suggest this technology could be used to enhance bone fusion and improve healing after skeletal injury. 相似文献
26.
Japanese encephalitis virus (JEV) is a neurotropic flavivirus, which causes viral encephalitis leading to death in about 20–30% of severely-infected people. Although JEV is known to be a neurotropic virus its replication in non-neuronal cells in peripheral tissues is likely to play a key role in viral dissemination and pathogenesis. We have investigated the effect of JEV infection on cellular junctions in a number of non-neuronal cells. We show that JEV affects the permeability barrier functions in polarized epithelial cells at later stages of infection. The levels of some of the tight and adherens junction proteins were reduced in epithelial and endothelial cells and also in hepatocytes. Despite the induction of antiviral response, barrier disruption was not mediated by secreted factors from the infected cells. Localization of tight junction protein claudin-1 was severely perturbed in JEV-infected cells and claudin-1 partially colocalized with JEV in intracellular compartments and targeted for lysosomal degradation. Expression of JEV-capsid alone significantly affected the permeability barrier functions in these cells. Our results suggest that JEV infection modulates cellular junctions in non-neuronal cells and compromises the permeability barrier of epithelial and endothelial cells which may play a role in viral dissemination in peripheral tissues. 相似文献
27.
Ridim D. Mote Jyoti Yadav Surya Bansi Singh Mahak Tiwari Shinde Laxmikant V Shivprasad Patil Deepa Subramanyam 《The Journal of biological chemistry》2020,295(49):16888
Mouse embryonic stem cells (mESCs) display unique mechanical properties, including low cellular stiffness in contrast to differentiated cells, which are stiffer. We have previously shown that mESCs lacking the clathrin heavy chain (Cltc), an essential component for clathrin-mediated endocytosis (CME), display a loss of pluripotency and an enhanced expression of differentiation markers. However, it is not known whether physical properties such as cellular stiffness also change upon loss of Cltc, similar to what is seen in differentiated cells, and if so, how these altered properties specifically impact pluripotency. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking Cltc display higher Young''s modulus, indicative of greater cellular stiffness, compared with WT mESCs. The increase in stiffness was accompanied by the presence of actin stress fibers and accumulation of the inactive, phosphorylated, actin-binding protein cofilin. Treatment of Cltc knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young''s modulus to values similar to those obtained with WT mESCs. However, a rescue in the expression profile of pluripotency factors was not obtained. Additionally, whereas WT mouse embryonic fibroblasts could be reprogrammed to a state of pluripotency, this was inhibited in the absence of Cltc. This indicates that the presence of active CME is essential for the pluripotency of embryonic stem cells. Additionally, whereas physical properties may serve as a simple readout of the cellular state, they may not always faithfully recapitulate the underlying molecular fate. 相似文献
28.
29.
Xiaohua Xu Silis Y. Jiang Tse-Yao Wang Yuntao Bai Mianhua Zhong Aixia Wang Morton Lippmann Lung-Chi Chen Sanjay Rajagopalan Qinghua Sun 《PloS one》2013,8(8)
Objectives
Studies have shown that chronic exposure to ambient fine particulate matter (less than 2.5 µm in aerodynamic diameter, PM2.5) pollution induces insulin resistance through alterations in inflammatory pathways. It is critical to study how the immune system responds to this stimulant, which has been linked to cardiovascular and autoimmune diseases, but few studies have been focused on such involvement of both neutrophils and monocytes in a timely manner. We hypothesized that the neutrophil was involved in the inflammatory response to air pollution.Methods and Results
C57BL/6 mice were exposed to PM2.5 or filtered air (6 hours/day, 5 days/week) for 5, 14, and 21 days, respectively, in Columbus, OH. At the end of each of the exposure periods, we investigated the inflammatory response through flow cytometry, histology, intravital microscopy, and real-time PCR. PM2.5-exposed mice demonstrated a significant inflammatory response after 5 days of exposure. In the lung tissue and bronchoalveolar lavage fluid, monocytes/macrophages showed a transient response, while neutrophils showed a cumulative response. In addition, exposure to PM2.5 resulted in elevation of the monocyte chemoattractant protein 1 (MCP-1) cytokine, a monocyte/macrophage attractant in blood, at an early stage of exposure.Conclusions
These findings suggest that PM2.5 exposure induces the inflammatory responses from both macrophages and neutrophils involvement. 相似文献30.
Viswanathan Rajagopalan Youhua Zhang Kaie Ojamaa Yue-feng Chen Alessandro Pingitore Christine J. Pol Debra Saunders Krithika Balasubramanian Rheal A. Towner A. Martin Gerdes 《PloS one》2016,11(3)