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   2879篇
  免费   164篇
  国内免费   2篇
  2022年   15篇
  2021年   32篇
  2020年   20篇
  2019年   19篇
  2018年   26篇
  2017年   18篇
  2016年   60篇
  2015年   68篇
  2014年   102篇
  2013年   164篇
  2012年   135篇
  2011年   144篇
  2010年   83篇
  2009年   90篇
  2008年   158篇
  2007年   159篇
  2006年   160篇
  2005年   139篇
  2004年   158篇
  2003年   138篇
  2002年   149篇
  2001年   70篇
  2000年   74篇
  1999年   74篇
  1998年   44篇
  1997年   35篇
  1996年   33篇
  1995年   44篇
  1994年   37篇
  1993年   24篇
  1992年   50篇
  1991年   49篇
  1990年   37篇
  1989年   45篇
  1988年   30篇
  1987年   33篇
  1986年   25篇
  1985年   35篇
  1984年   25篇
  1983年   24篇
  1982年   13篇
  1981年   27篇
  1980年   22篇
  1979年   19篇
  1978年   15篇
  1977年   12篇
  1976年   16篇
  1975年   12篇
  1974年   16篇
  1973年   9篇
排序方式: 共有3045条查询结果,搜索用时 15 毫秒
971.
Dioscorea batatas Decne (DBD) is used to heal various disorders of the kidney and lungs as an herbal agent in Korea. The purpose of the present study was to determine whether the DBD glycoprotein regulates the inflammatory reaction stimulated by phorbol-12-myristate 13-acetate plus calcium ionophore A23187 (PMACI) in human mast cells (HMC-1). The results indicate that DBD glycoprotein decreased gene expression of interleukin (IL)-1β and cyclooxygenase (COX)-2 in PMACI-stimulated HMC-1 cells through blocking of phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) and p38 MAPK and DNA binding activities of nuclear factor (NF)-κB and activator protein (AP)-1. The production of intracellular reactive oxygen species (ROS) and nitric oxide (NO) is gradually reduced by concentration-dependent DBD glycoprotein treatment in PMACI-stimulated HMC-1 cells. Hence, we propose the hypothesis that DBD glycoprotein can serve as a potent anti-inflammatory agent in the treatment of inflammatory allergic diseases through inhibition of inflammation-related signal transduction in mast cell activation.  相似文献   
972.
A series of novel curcumin analogs, symmetrical dienones, were previously shown to possess cytotoxic, anti-angiogenic and anti-tumor activities. Analogs 1 (EF24) and 2 (EF31) share the dienone scaffold and serve as Michael acceptors. We propose that the anti-cancer effects of 1 and 2 are mediated in part by redox-mediated induction of apoptosis. In order to support this concept, 1 and 2 were treated with l-glutathione (GSH) and cysteine-containing dipeptides under mild conditions to form colorless water-soluble adducts, which were identified by LC/MS. Comparison of the cytotoxic action of 1, 2 and the corresponding conjugates, 1-(GSH)2 and 2-(GSH)2, illustrated that the two classes of compounds exhibit essentially identical cell killing capabilities. Compared with the yellow, somewhat light sensitive and nearly water insoluble compounds 1 and 2, the glutathione conjugates represent a promising new series of stable and soluble anti-tumor pro-drugs.  相似文献   
973.

Purpose

we aim to examine whether adding exercise has impact on obesity prevention and bone metabolism in senior rats, to which dietary obesity was induced through skim milk intake.

Methods

We used 47, 14-week old Sprague -Dawley (SD) female rats (CLEA Japan, Inc.). The Rats were separated into four random groups: 1) a Non-Ex group with a normal diet (n = 12), 2) an Ex group with a normal diet (n = 12), 3) a Non-Ex group with a skim milk diet (n = 11), and 4) an Ex group with a skim milk diet (n = 12). As the exercise for each Ex group, rats ran on a treadmill starting at 27-week old (TREADMILL CONTROL LE8710 and TREADMILL CONTROL LE8700, Harvard Bioscience). Training protocol stipulated a frequency of five times a week for 12 weeks.

Results

The leptin concentration differed with dietary content: compared to the Ex group with a skim milk diet, Non-Ex and Ex groups with a normal diet showed significantly higher values (p < 0.05). The Ex group had significantly lower values in both the normal diet and skim milk diet groups with or without exercise (p < 0.05). Compared to the Non-Ex group with a normal diet, BS/BV (mm2/mm3), BV/TV (%), Tb.Th (μm), TBPf (/mm) and Tb.N (/mm) had significantly lower in the Ex group, the Ex and Non-Ex groups with a whey protein diet, and the Ex group with a skim milk protein diet (p < 0.05).

Conclusion

These findings suggest that senior female rats fed SMP would have higher bone structural and strength parameters than rats fed a normal diet.  相似文献   
974.
TNF and Fas/FasL are vital components, not only in hepatocyte injury, but are also required for hepatocyte regeneration. Liver F4/80+Kupffer cells are classified into two subsets; resident radio-resistant CD68+cells with phagocytic and bactericidal activity, and recruited radio-sensitive CD11b+cells with cytokine-producing capacity. The aim of this study was to investigate the role of these Kupffer cells in the liver regeneration after partial hepatectomy (PHx) in mice. The proportion of Kupffer cell subsets in the remnant liver was examined in C57BL/6 mice by flow cytometry after PHx. To examine the role of CD11b+Kupffer cells/Mφ, mice were depleted of these cells before PHx by non-lethal 5 Gy irradiation with or without bone marrow transplantation (BMT) or the injection of a CCR2 (MCP-1 receptor) antagonist, and liver regeneration was evaluated. Although the proportion of CD68+Kupffer cells did not significantly change after PHx, the proportion of CD11b+Kupffer cells/Mφ and their FasL expression was greatly increased at three days after PHx, when the hepatocytes vigorously proliferate. Serum TNF and MCP-1 levels peaked one day after PHx. Irradiation eliminated the CD11b+Kupffer cells/Mφ for approximately two weeks in the liver, while CD68+Kupffer cells, NK cells and NKT cells remained, and hepatocyte regeneration was retarded. However, BMT partially restored CD11b+Kupffer cells/Mφ and recovered the liver regeneration. Furthermore, CCR2 antagonist treatment decreased the CD11b+Kupffer cells/Mφ and significantly inhibited liver regeneration. The CD11b+Kupffer cells/Mφ recruited from bone marrow by the MCP-1 produced by CD68+Kupffer cells play a pivotal role in liver regeneration via the TNF/FasL/Fas pathway after PHx.  相似文献   
975.
Recently, iPSCs have attracted attention as a new source of cells for regenerative therapies. Although the initial method for generating iPSCs relied on dermal fibroblasts obtained by invasive biopsy and retroviral genomic insertion of transgenes, there have been many efforts to avoid these disadvantages. Human peripheral T cells are a unique cell source for generating iPSCs. iPSCs derived from T cells contain rearrangements of the T cell receptor (TCR) genes and are a source of antigen-specific T cells. Additionally, T cell receptor rearrangement in the genome has the potential to label individual cell lines and distinguish between transplanted and donor cells. For safe clinical application of iPSCs, it is important to minimize the risk of exposing newly generated iPSCs to harmful agents. Although fetal bovine serum and feeder cells have been essential for pluripotent stem cell culture, it is preferable to remove them from the culture system to reduce the risk of unpredictable pathogenicity. To address this, we have established a protocol for generating iPSCs from human peripheral T cells using Sendai virus to reduce the risk of exposing iPSCs to undefined pathogens. Although handling Sendai virus requires equipment with the appropriate biosafety level, Sendai virus infects activated T cells without genome insertion, yet with high efficiency. In this protocol, we demonstrate the generation of iPSCs from human peripheral T cells in feeder-free conditions using a combination of activated T cell culture and Sendai virus.  相似文献   
976.
The ‘3-second rule’ has been proposed based on miscellaneous observations that a time period of around 3 seconds constitutes the fundamental unit of time related to the neuro-cognitive machinery in normal humans. The aim of paper was to investigate the temporal processing in patients with spinocerebellar ataxia type 6 (SCA6) and SCA31, pure cerebellar types of spinocerebellar degeneration, using a synchronized tapping task. Seventeen SCA patients (11 SCA6, 6 SCA31) and 17 normal age-matched volunteers participated. The task required subjects to tap a keyboard in synchrony with sequences of auditory stimuli presented at fixed interstimulus intervals (ISIs) between 200 and 4800 ms. In this task, the subjects required non-motor components to estimate the time of forthcoming tone in addition to motor components to tap. Normal subjects synchronized their taps to the presented tones at shorter ISIs, whereas as the ISI became longer, the normal subjects displayed greater latency between the tone and the tapping (transition zone). After the transition zone, normal subjects pressed the button delayed relative to the tone. On the other hand, SCA patients could not synchronize their tapping with the tone even at shorter ISIs, although they pressed the button delayed relative to the tone earlier than normal subjects did. The earliest time of delayed tapping appearance after the transition zone was 4800 ms in normal subjects but 1800 ms in SCA patients. The span of temporal integration in SCA patients is shortened compared to that in normal subjects. This could represent non-motor cerebellar dysfunction in SCA patients.  相似文献   
977.
978.

Objectives

The purpose of the present study was to investigate potential effects of ankle–foot orthoses (AFOs) on the functional recovery of post-acute stroke patients following rehabilitation.

Subjects and Methods

This study is a retrospective cohort study. Participants were in-hospital stroke patients registered in the Japan Rehabilitation Database between 2005 and 2012. A total of 1862 patients were eligible after applying exclusion criteria. Propensity score analysis was applied to adjust for potential bias and to create two comparable groups. An additional subset analysis focused on Functional Independence Measure (FIM) scores on admission.

Results

In this sample, 30.7% of 1863 eligible patients were prescribed AFOs. Propensity score matched analysis showed that patients with AFOs had significantly higher scores than those without them for discharge FIM (mean: 91.3 vs 85.8; p=0.02), FIM gain (mean: 28.9 vs 23.5; p<0.001), and FIM efficiency (mean: 0.27 vs 0.22; p<0.001). Inverse probability weighting analysis showed similar results. In the subset analysis, patients with AFOs had significantly higher discharge FIM compared with those without them in the low admission FIM subgroup only. In addition, patients with AFOs performed independent exercise more than those without them (p<0.001).

Conclusions

These data suggest that stroke survivors may have better functional recovery if they are prescribed an AFO than if they are not prescribed an AFO. The use of AFOs is considered to be a feasible option to improve functional recovery of stroke rehabilitation patients.  相似文献   
979.
980.
Siglecs, sialic acid-recognizing Ig-superfamily lectins, regulate various aspects of immune responses, and have also been shown to induce the endocytosis of binding materials such as anti-Siglec antibodies or sialic acid-harboring bacteria. In this study, we demonstrated that the expression of Siglec-9 enhanced the transfection efficiency of several cell lines such as macrophage RAW264 and non-hematopoietic 293FT cells. We applied this finding to the production of a lentiviral vector in which cells were transfected simultaneously with multiple vectors, and achieved a twice increase in viral production levels. Furthermore, 293FT cells expressing lectin-defective Siglec-9 produced three- to seven-fold higher titer of viral vector compared with parental 293FT cells. These results suggest that Siglec-9 enhanced lentiviral vector production in a lectin-independent manner.  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