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   1388篇
  免费   66篇
  1454篇
  2024年   4篇
  2023年   14篇
  2022年   49篇
  2021年   80篇
  2020年   44篇
  2019年   62篇
  2018年   59篇
  2017年   64篇
  2016年   88篇
  2015年   120篇
  2014年   107篇
  2013年   172篇
  2012年   138篇
  2011年   113篇
  2010年   63篇
  2009年   44篇
  2008年   28篇
  2007年   37篇
  2006年   35篇
  2005年   28篇
  2004年   22篇
  2003年   11篇
  2002年   12篇
  2001年   1篇
  2000年   4篇
  1999年   4篇
  1998年   6篇
  1997年   4篇
  1996年   5篇
  1995年   3篇
  1994年   3篇
  1993年   3篇
  1992年   2篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1985年   1篇
  1984年   6篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1975年   1篇
  1974年   2篇
  1973年   3篇
排序方式: 共有1454条查询结果,搜索用时 12 毫秒
71.

Objective

In Malaysia, futsal is a popular sport played by individuals across all ages and genders. Despite its popularity, information on futsal related injury in Malaysia is not available. The purpose of this study is to examine the injury incidence and injury patterns among amateur men and women futsal players in Malaysia.

Methods

Players reported injury to the tournament medical team during the FELDA/FAM National Futsal League 2010 were interviewed and assessed by a Sports Medicine registrar. Player''s socio-demographic profiles and information about the injury were documented in the injury report form adapted from medical report form used by FIFA: Medical Assessment and Research Centre (F-Marc).

Results

A total of 86 injuries were reported from 141 matches, equivalent to an incidence of 91.5 injuries per 1000 player hours (95% CI 72.2 to 110.8), or 61.0 injuries per 1000 player matches (95% CI 48.1 to 73.9). Most were minor injuries resulted from contact with another player. Injuries often involved the lower extremity (44%) followed by the trunk (14%) and the upper limb (13%). Ankle (n = 7; 39%) and knee (n = 6; 33%) sprains were the most prevalent diagnoses of time-loss injuries. A significant association between time-loss and type of injury was found χ 2 (1,N = 86) = 3.99, p = 0.04. In addition, time-loss injury was significantly associated with playing surface χ 2 (1,N = 86) = 10.11, p = 0.018.

Conclusion

The injury rate during the FELDA/FAM National Amateur Futsal Men''s League in Malaysia was lower compared with previous Futsal World Cups competition. Most injuries resulted from contact with another player were minor and did not lead to time-loss from participation. Time-loss injury was significantly associated with type of injury and playing surface.  相似文献   
72.
73.
A bolus treatment (e.g., 25 mg) of prostaglandin F(2alpha) (PGF) in the study of luteolysis in cattle results in dubious interpretations. Therefore, in experiment 1 of the present study, a 13,14-dihydro-15-keto-PGF (PGFM) pulse was simulated by incremental intrauterine (IU) infusion of PGF for 2.7 h on Day 14 postovulation. Concentrations of PGFM during the first hour of infusion and at the maximum were not different between simulated (n = 7) and spontaneous (n = 7) pulses. In experiment 2, four groups (n = 6 per group) were treated at Minute 0 (beginning of infusion) as follows: saline (infused IU), PGF (infused IU), acyline/saline, and acyline/PGF. Two hours before Minute 0, each heifer was given flunixin meglumine to inhibit endogenous PGF secretion, and heifers in the acyline/saline and acyline/PGF groups were given acyline to inhibit luteinizing hormone (LH). Plasma progesterone concentrations were similar among groups during Minutes 0 to 60, with no indication of an initial transient progesterone increase in the two PGF groups. Progesterone began to decrease in the PGF groups at Minute 60 and to rebound at Minute 135 after the PGFM peak at Minute 120. The rebound was complete in association with an increase in LH in the PGF group, but it was not complete when LH was inhibited in the acyline/PGF group. Luteal blood flow increased during PGF infusion in the two PGF groups and remained elevated for approximately 2 h after the PGFM peak in the PGF group but not in the acyline/PGF group. Novel findings were that an initial transient increase in progesterone did not occur with the simulated PGFM pulse and that LH stimulated a progesterone rebound and maintained the elevated luteal blood flow after the PGFM peak.  相似文献   
74.
Pseudogenes are considered to be nonfunctional genes that lack a physiological role. By screening 3985 Escherichia coli mutants using chemochromic membranes, we found four pseudogenes involved in hydrogen metabolism. Knockouts of pseudogenes ydfW and ypdJ had a defective hydrogen phenotype on glucose and formate, respectively. Also, the knockout of pseudogene yqiG formed hydrogen from formate but not from glucose. For the yqiG mutant, 100% hydrogen recovery was obtained by the complementation of YqiG via a plasmid. The knockout of pseudogene ylcE showed hydrogen deficiency in minimal media which suggested that the role of YlcE is associated with cell growth. Hence, the products of these four pseudogenes play an important physiological role in hydrogen production in E. coli.  相似文献   
75.
To investigate which matrix metalloproteinases (MMPs) are more likely to be involved in the angiogenic process in proliferative diabetic retinopathy (PDR), we measured the levels of MMPs in the vitreous fluid from patients with PDR and controls and correlated these levels with the levels of vascular endothelial growth factor (VEGF). Vitreous samples from 32 PDR and 24 nondiabetic patients were studied by mosaic multiplex MMPs enzyme-linked immunosorbent assay (ELISA), single ELISA, Western blot and zymography analysis. Epiretinal membranes from 11 patients with PDR were studied by immunohistochemistry. MMP-8 and MMP-13 were not detected. ELISA, Western blot and gelatin ymography assays revealed significant increases in the expression levels of MMP-1, MMP-7, MMP-9 and VEGF in vitreous samples from PDR patients compared to nondiabetic controls, whereas MMP-2 and MMP-3 were not upregulated in vitreous samples from PDR patients. Significant correlations existed between ELISA and zymography assays for the quantitation of MMP-2 (r=0.407; p=0.039) and MMP-9 (r=0.711; p<0.001). Significant correlations were observed between levels of VEGF and levels of MMP-1 (r=0.845; P<0.001) and MMP-9 (r=0.775; p<0.001), and between levels of MMP-1 and MMP-9 (r=0.857; p<0.001). In epiretinal membranes, cytoplasmic immunoreactivity for MMP-9 was present in vascular endothelial cells and stromal monocytes/macrophages and neutrophils. Our findings suggest that among the MMPs measured, MMP-1 and MMP-9 may contribute to the angiogenic switch in PDR.  相似文献   
76.
The role of niacin’s metabolite, nicotinamide adenine dinucleotide (NAD), in DNA repair via base-excision repair pathway is well documented. We evaluated if niacin deficiency results in genetic instability in normal human fetal lung fibroblasts (MRC-5), and further, does it leads to enhanced accumulation of cigarette smoke–induced genetic damage? MRC-5 cells were grown discretely in niacin-proficient/deficient media, and exposed to nicotine-derived nitrosamine ketone (NNK, a cigarette smoke carcinogen). Niacin deficiency abated the NAD polymerization, augmented the spontaneous induction of micronuclei (MN) and chromosomal aberrations (CA) and raised the expression of 10 genes and suppressed 12 genes involved in different biological functions. NNK exposure resulted in genetic damage as measured by the induction of MN and CA in cells grown in niacin-proficient medium, but the damage became practically marked when niacin-deficient cells were exposed to NNK. NNK exposure raised the expression of 16 genes and suppressed the expression of 56 genes in cells grown in niacin-proficient medium. NNK exposure to niacin-deficient cells raised the expression of eight genes including genes crucial in promoting cancer such as FGFR3 and DUSP1 and suppressed the expression of 33 genes, including genes crucial in preventing the onset and progression of cancer like RASSF2, JUP, and IL24, in comparison with the cells grown in niacin-proficient medium. Overall, niacin deficiency interferes with the DNA damage repair process induced by chemical carcinogens like NNK, and niacin-deficient population are at the higher risk of genetic instability caused by cigarette smoke carcinogen NNK.  相似文献   
77.
Due to the critical role of cellular enzymes necessary for cell proliferation by deciphering topological hurdles in the process of DNA replication, topoisomerases have been one of the major targets in the anticancer drug development area. A need, therefore, arises for new metallodrugs that specifically recognizes DNA and inhibits the activity of topoisomerase enzymes, herein, we report the synthesis and characterization of new metal-based glycoconjugate entities containing heterobimetallic core CuII–SnIV (1) and NiII–SnIV (2) derived from N-glycoside ligand (L). The optimized structure of complex 1 and other significant vibrational modes have been explained using dispersion corrected B3LYP/DFT calculations. In vitro DNA binding profile of the L and both the complexes 1 and 2 were done by various biophysical studies. Complex 1 breaks pBR322 DNA via a hydrolytic means which was validated by T4 DNA enzymatic assay. To get a mechanistic insight of mode of action topoisomerase I (Topo I) inhibition assay was carried out. Also, we have taken the help of molecular modeling studies in accordance with experimental findings. In vitro cytotoxicity of the complex 1 was evaluated against a panel of cancer cells which exhibited remarkably good anticancer activity (GI50 values <10 μg/ml). Moreover, intracellular localization of the complex 1 was visualized by confocal microscopy against HeLa cells.  相似文献   
78.
Integrin CD11b/CD18 is a key adhesion receptor that mediates leukocyte migration and immune functions. Leukadherin-1 (LA1) is a small molecule agonist that enhances CD11b/CD18-dependent cell adhesion to its ligand ICAM-1. Here, we used single-molecule force spectroscopy to investigate the biophysical mechanism by which LA1-activated CD11b/CD18 mediates leukocyte adhesion. Between the two distinct populations of CD11b/CD18:ICAM-1 complex that participate in cell adhesion, the cytoskeleton(CSK)-anchored elastic elements and the membrane tethers, we found that LA1 enhanced binding of CD11b/CD18 on K562 cells to ICAM-1 via the formation of long membrane tethers, whereas Mn2+ additionally increased ICAM-1 binding via CSK-anchored bonds. LA1 activated wild-type and LFA1−/− neutrophils also showed longer detachment distances and time from ICAM-1-coated atomic force microscopy tips, but significantly lower detachment force, as compared to the Mn2+-activated cells, confirming that LA1 primarily increased membrane-tether bonds to enhance CD11b/CD18:ICAM-1 binding, whereas Mn2+ induced additional CSK-anchored bond formation. The results suggest that the two types of agonists differentially activate integrins and couple them to the cellular machinery, providing what we feel are new insights into signal mechanotransduction by such agents.  相似文献   
79.
Mycopathologia - Candida albicans has been reported globally as the most widespread pathogenic species contributing candidiasis from superficial to systemic infections in immunocompromised...  相似文献   
80.
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