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   211篇
  免费   20篇
儿科学   5篇
妇产科学   2篇
基础医学   24篇
口腔科学   1篇
临床医学   25篇
内科学   39篇
神经病学   18篇
特种医学   16篇
外科学   17篇
综合类   2篇
预防医学   77篇
眼科学   1篇
药学   4篇
  2023年   1篇
  2022年   5篇
  2021年   5篇
  2020年   4篇
  2019年   4篇
  2018年   8篇
  2017年   9篇
  2016年   9篇
  2015年   5篇
  2014年   11篇
  2013年   19篇
  2012年   17篇
  2011年   25篇
  2010年   10篇
  2009年   12篇
  2008年   16篇
  2007年   4篇
  2006年   9篇
  2005年   10篇
  2004年   5篇
  2003年   13篇
  2002年   4篇
  2001年   6篇
  2000年   2篇
  1999年   3篇
  1998年   1篇
  1996年   1篇
  1991年   1篇
  1990年   3篇
  1989年   1篇
  1986年   3篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1974年   1篇
排序方式: 共有231条查询结果,搜索用时 15 毫秒
11.
In keeping with this review-series theme, we question whether the morning surge in blood pressure (MSBP) is a benign response to the physiological challenges during the first 3 h after waking, or is it clinically important? Therefore, we scrutinise the circadian-related mechanisms, the measurement methods and the prognostic value of the MSBP. The MSBP is relatively small (<2 mmHg) under constant routine conditions. Nevertheless, the blood pressure response to exercise can be 8–14 mm Hg greater in the morning vs. afternoon, even when prior sleep is controlled. Systematic bias between MSBP methods can be >10 mmHg. The “sleep-trough” method provides the largest MSBP (≈25 mmHg), but the sensitivity of MSBP to a treatment/intervention depends largely on its repeatability. The repeatability standard deviation (SD) for most MSBP methods is ≈8 mm Hg. While the magnitude of this SD precludes the use of MSBP for diagnostic decisions on individual patients, sample sizes for future intervention studies may be feasible, depending on the minimal clinically important difference in MSBP. This difference is somewhat unclear given that a large MSBP has recently been reported to predict a reduced, rather than a higher, risk of cardiovascular disease, although this particular study has been criticised. The MSBP is also naturally correlated to changes in physical activity and nocturnal “dipping” status. Therefore, it is important to account for these potential confounders of the MSBP, so that more precise knowledge about its clinical significance is gained, thereby providing a sound rationale for physiological investigation and translational research.  相似文献   
12.
13.
14.
Objectives: To determine individual differences in the impact of illness on the change in performance of swimmers in international competitions. Methods: Subjects were members of the Australian swimming team (33 male and 39 female, aged 15–27 years). Swimmers provided a weekly seven day recall of symptoms of illness during final six weeks of preparations for international competition over a three year period. Swimmers were categorised as either ill (one or more episodes of illness) or healthy. The measure of performances was the international point score. Mean changes in points score were calculated for healthy and ill swimmers between a national championship and an international competition (∼16 weeks later). Likelihoods of substantial effects of illness on an individual''s true change in performance (beneficial/trivial/harmful) were estimated from means and standard deviations, assuming a smallest substantial change of 6 points. Results: Illness was reported before international performances by 38% of female and 35% of male swimmers. For female swimmers the change in performance was –3.7 (21.5) points (mean (SD)) with illness and –2.6 (19.0) points when healthy; for male swimmers the changes were –1.4 (17.5) points with illness and 5.6 (13.2) points when healthy. The likelihoods that illness had a substantial beneficial/trivial/harmful effect on performance of an individual swimmer were 32%/31%/37% for female and 17%/31%/52% for male participants (90% confidence limits ∼±10% to 20%). Conclusions: Although mild illness had only a trivial mean effect on female swimmers and a small harmful mean effect on male swimmers, there were substantial chances of benefit and harm for individuals.  相似文献   
15.
Apoptosis-based evaluation of chemosensitivity in ovarian cancer patients   总被引:2,自引:0,他引:2  
OBJECTIVE: Induction of apoptosis in target cells is a key mechanism by which chemotherapy induces cell killing. We have established an in vitro system for determining the chemosensitivity of epithelial ovarian cancer cells to carboplatin and paclitaxel (Taxol). Practical assays to predict the likelihood of individual tumor sensitivity are needed to facilitate the choice of adequate treatment. We sought to determine whether epithelial ovarian cancer cells (EOC) collected from the ascites fluid of patients known to be clinically chemosensitive or chemoresistant to carboplatin and paclitaxel would show a similar response to chemotherapeutic drugs after in vitro treatment. METHODS: Thirteen patients with stage III and IV ovarian cancer treated with carboplatin and paclitaxel were studied. Caspase-3 activation was used as a surrogate marker for activation of chemotherapy-induced programmed cell death. We compared the in vitro apoptotic response to the clinical response of the patients from whom the tumor cells were isolated. Clinical sensitivity was defined as no evidence of disease recurrence for 6 months after optimal debulking surgery and completion of chemotherapy. RESULTS: Of seven chemosensitive patients, five cell samples treated in vitro had increased caspase-3 activity in response to both carboplatin and paclitaxel. Five of six chemoresistant cases did not show caspase-3 activity in response to only one or to neither agent. CONCLUSION: Quantifiable markers of apoptosis such as caspase-3 activation have the potential to predict the clinical response to chemotherapy. Application of this assay in clinical laboratories could optimize the potential for efficient treatment and avoid the toxicities of ineffective drugs.  相似文献   
16.
The effect of frequency of feeding (once daily or six equal portions at intervals of 3 h) of diets containing lysine (6.4 g/kg) supplied as either protein-bound or free lysine on the metabolism of essential amino acids was investigated in pigs over the 23-34 kg weight range. The amounts of radioactivity from 14CO2 produced by the pigs given oral doses of [14C]lysine or [14C]phenylalanine were determined. [14C]Lysine was confirmed to be unsuitable presumably because the oral dose was diluted by the dietary free lysine or was absorbed ahead of the protein-bound lysine, or both. With [14C]phenylalanine addition, there was a significantly (P less than 0.01) greater production of 14CO2 by pigs fed once daily on the diet containing free lysine. However, with frequent feeding, there was no significant difference (P less than 0.05) in the amount of 14CO2 produced by pigs from [14C]phenylalanine for either diet. Growth responses of the pigs were lower when the diet containing free lysine was given once daily (P less than 0.01) but were similar when the diets were given frequently. It is concluded that the more rapid absorption of free lysine by growing pigs fed once daily results in an imbalance of amino acids at the sites of metabolism. This leads to greater oxidation of essential amino acids than occurs when all the amino acids are supplied in the protein-bound form. With frequent feeding, a better balanced supply of amino acids is absorbed, leading to similar rates of oxidation of excess essential amino acids from diets containing either free or protein-bound lysine.  相似文献   
17.
1. The availability of lysine in four meat meals (MMs), four meat and bone meals (MBMs) and two blood meals was determined using the slope-ratio assay with growing pigs, rats and chicks and with two chemical techniques. 2. The availability of lysine (proportion of total) in the eight MMs or MBMs ranged from 0.48 to 0.88 for pigs, from 0.49 to 0.88 for rats and from 0.68 to 0.88 for chicks. There was no apparent relation between the availability estimates for pigs, rats and chicks for the individual meals. 3. For the two blood meals, availability estimates were 1.03 and 1.13 for pigs, 0.81 and 0.80 for rats and 1.07 and 1.02 for chicks. 4. Values for the indirect and direct 1-fluoro-2,4-dinitrobenzene-'available'-lysine assays ranged from 0.77 to 0.88 and 0.78 to 0.93 respectively for the eight MMs and MBMs. There appeared to be no relation between these values and the pig estimates.  相似文献   
18.
19.
Anaerobic threshold (AT), determined by cardiopulmonary exercise testing (CPET), is a well‐documented measure of pre‐operative fitness, although its reliability in patient populations is uncertain. Our aim was to assess the reliability of AT measurement in patients with abdominal aortic aneurysms. Eighteen patients were recruited. CPET was performed four times over a 6‐week period. We examined shifts in the mean AT to evaluate systematic bias with random measurement error assessed using typical within‐patient error and intraclass correlation coefficient (ICC, 3,1) statistics. There was no significant or clinically substantial change in mean AT across the tests (p = 0.68). The typical within‐patient error expressed as a percentage coefficient of variation was 10% (95% CI, 8–13%), with an ICC of 0.74 (95% CI, 0.55–0.89). We consider the reliability of the AT to be acceptable, supporting its clinical validity and utility as an objective marker of pre‐operative fitness in this population.  相似文献   
20.
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