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   1809篇
  免费   184篇
  国内免费   91篇
耳鼻咽喉   4篇
儿科学   71篇
妇产科学   19篇
基础医学   163篇
口腔科学   29篇
临床医学   476篇
内科学   387篇
皮肤病学   84篇
神经病学   60篇
特种医学   96篇
外科学   208篇
综合类   110篇
预防医学   91篇
眼科学   16篇
药学   220篇
中国医学   5篇
肿瘤学   45篇
  2021年   28篇
  2020年   17篇
  2019年   18篇
  2018年   24篇
  2017年   26篇
  2016年   17篇
  2015年   22篇
  2014年   37篇
  2013年   58篇
  2012年   36篇
  2011年   59篇
  2010年   55篇
  2009年   44篇
  2008年   41篇
  2007年   87篇
  2006年   50篇
  2005年   63篇
  2004年   54篇
  2003年   51篇
  2002年   42篇
  2001年   46篇
  2000年   53篇
  1999年   57篇
  1998年   66篇
  1997年   67篇
  1996年   49篇
  1995年   53篇
  1994年   54篇
  1993年   42篇
  1992年   43篇
  1991年   33篇
  1990年   53篇
  1989年   58篇
  1988年   55篇
  1987年   33篇
  1986年   32篇
  1985年   23篇
  1984年   26篇
  1983年   22篇
  1982年   19篇
  1981年   17篇
  1980年   16篇
  1979年   14篇
  1978年   15篇
  1977年   15篇
  1976年   19篇
  1975年   15篇
  1966年   13篇
  1965年   13篇
  1959年   13篇
排序方式: 共有2084条查询结果,搜索用时 15 毫秒
1.
Objective: To examine (i) the associations between physical activity dimensions, cardiorespiratory fitness and body composition and, (ii) the associations between physical activity dimensions, cardiorespiratory fitness, body composition and biomarkers of cardiometabolic health in persons with spinal cord injury (SCI).

Methods: A cross-sectional prospective cohort study with 7-day follow-up was conducted. Body composition, cardiorespiratory fitness and biomarkers of cardiometabolic health were measured in thirty-three participants with SCI (> 1 year post injury). Physical activity dimensions were objectively assessed over 7-days.

Results: Activity energy expenditure (r =.43), physical activity level (r =.39), and moderate-to-vigorous physical activity (MVPA) (r =.48) were significantly (P < 0.001) associated with absolute (L/min) peak oxygen uptake (?O2 peak). ?O2 peak was significantly higher in persons performing ≥150 MVPA minutes/week compared to <40 minutes/week (P?=?0.003). Individual physical activity dimensions were not significantly associated with biomarkers of cardiometabolic health. However, body composition characteristics (BMI, waist and hip circumference) showed significant (P < 0.04), moderate (r >.30) associations with parameters of metabolic regulation, lipid profiles and inflammatory biomarkers. Relative ?O2 peak (ml/kg/min) was moderately associated with only insulin sensitivity (r?=?0.37, P?=?0.03).

Conclusions: Physical activity dimensions are associated with cardiorespiratory fitness; however, stronger and more consistent associations suggest that poor cardiometabolic health is associated with higher body fat content. Given these findings, the regulation of energy balance should be an important consideration for researchers and clinicians looking to improve cardiometabolic health in persons with SCI.  相似文献   

2.
3.
4.
5.
Summary Infection due to theMycobacterium avium complex (MAC) accounts for the most frequent AIDS-related opportunistic infections, but MAC infection is usually not the first AIDS-defining event that a patient infected with HIV experiences. The incidence increases linearly over time, at a rate of 20 to 25% per year, after a patient's first AIDS-defining event, and the incidence increases exponentially as the CD4+ cell count approaches zero. There is evidence that MAC may eventually infect most if not all HIV-infected patients who do not die from another HIV-related event. Since MAC infection contributes substantially to the morbidity and mortality of AIDS patients, prophylaxis appears to be mandatory. Rifabutin was the first drug which was shown to be effective in preventing MAC infection, and, recently, prophylaxis with clarithromycin was also found to prevent the disease. The optimal approach to prophylaxis still needs to be defined. Since a large majority of MAC infections occur in patients with CD4+ cell counts below 50/µl, recommendations regarding the prophylaxis of patients with a history of an AIDS-defining opportunistic event and a CD4+ cell count between 50 and 200/µl can be individualized, depending for example on how well the patient seems to be responding to antiretroviral treatment. Prophylaxis against MAC should be provided for any HIV-infected patient with a CD4+ cell count less than 50/µl.  相似文献   
6.
SUMMARY: The effect of mild acute tubular injury on the progression of tubulointerstitial fibrosis was studied in pair-fed uninephrectomized male Wistar rats with established adriamycin nephrosis ( n = 34). Rats were stratified into three groups according to endogenous creatinine clearance (CrCl), proteinuria (Upr) and body weight (BW): (i) group 1 (Fe, n = 12) received a single intraperitoneal injection of ferric nitrilotriacetate (5 mg Fe/kg BW); (ii) group 2 (G, n = 10) three daily subcutaneous injections of gentamicin (60 mg/kg BW) and; (iii) group 3 (C, n = 12) saline injections. Serial CrCl (day 2, day 5, weeks 2, 4, 6 and 8) and renal histology (week 8) were examined following administration of nephrotoxin. CrCl was reduced on d2 (Fe: 0.78 ± 0.23 mL/min; mean ± SD) and day 5 (G: 0.91 ± 0.36 mL/min) as compared with C (1.22 ± 0.12 mL/min; P <0.05). There was no change in the serum creatinine and functional recovery occurred by d5 (Fe) and week 2 (G). Upr decreased transiently in G at week 2 (G: 482 ± 208 mg/day vs C: 716 ± 233; P = 0.05) despite similar food intake, baseline Upr and CrCl. At week 8, CrCl in Fe (0.84 ± 0.40 mL/min) was similar to C (0.84 ± 0.58 mL/min), whereas in G it remained stable (1.27 ± 0.39 mL/min; P <0.05). By morphometric analysis, mean relative interstitial volume (RIV) and glomerulosclerosis (GS) in Fe (RIV: 28.5 ± 13.4%; GS: 10.3 ± 12.3%) was no different to C (RIV: 24.5 ± 12.5%; GS: 20.9 ± 20.0%), whereas both parameters were reduced in G (RIV: 14.1 ± 8.1%; GS: 4.0 ± 4.8%; P <0.05). Mild gentamicin nephrotoxicity therefore reduced the progression of adriamycin nephrosis. the mechanism of this finding is unclear, but it may relate to altered glomerular and tubular cell handling of protein.  相似文献   
7.
8.
9.
本文通过将无环鸟苷(acyclovir,简称ACV)2’位羟基分别与月桂酰氯或棕榈酰氯进行酯化反应,制得亲脂性前体药物无环鸟苷月桂酸酯和无环鸟苷棕榈酸酯(分别简称为C12-ACV和C16-ACV),使脂质体包封率从ACV的29.9%提高到C12-ACV的95.6%和C16-ACV的97.1%;漏泄实验表明在4℃透析60h后,一半以上的ACV从脂质体中漏泄,而C12-ACV和C16-ACV的滞留率分别为70%和80%;体外抗疱疹病毒的试验中,在最低试验浓度0.044μmol/L时,ACV不显示抗病毒活性,而C16-ACV脂质体抑制细胞病变率达75%,说明前体药物通过与脂质体脂膜的结合增加了药物的进入细胞能力,从而提高了ACV的抗病毒能力。  相似文献   
10.
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