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   263篇
  免费   24篇
  国内免费   10篇
耳鼻咽喉   2篇
儿科学   6篇
妇产科学   3篇
基础医学   15篇
口腔科学   4篇
临床医学   49篇
内科学   40篇
皮肤病学   5篇
神经病学   7篇
特种医学   10篇
外科学   18篇
综合类   30篇
预防医学   19篇
眼科学   5篇
药学   44篇
中国医学   31篇
肿瘤学   9篇
  2024年   2篇
  2023年   2篇
  2022年   5篇
  2021年   14篇
  2020年   9篇
  2019年   2篇
  2018年   4篇
  2017年   6篇
  2016年   2篇
  2015年   3篇
  2014年   6篇
  2013年   9篇
  2012年   10篇
  2011年   13篇
  2010年   9篇
  2009年   12篇
  2008年   17篇
  2007年   12篇
  2006年   14篇
  2005年   20篇
  2004年   13篇
  2003年   4篇
  2002年   5篇
  2001年   11篇
  2000年   4篇
  1999年   9篇
  1998年   5篇
  1997年   6篇
  1996年   10篇
  1995年   5篇
  1994年   5篇
  1993年   1篇
  1992年   7篇
  1991年   3篇
  1990年   1篇
  1989年   3篇
  1988年   4篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1983年   2篇
  1981年   1篇
  1966年   1篇
  1963年   2篇
  1962年   1篇
  1959年   3篇
  1958年   6篇
  1957年   5篇
  1949年   2篇
排序方式: 共有297条查询结果,搜索用时 47 毫秒
1.
BACKGROUND: Our aims in the present study were to estimate the influences of pain and urinary symptoms on quality of life, and to determine which of these two variables has the most predictive power with respect to quality of life in young men with chronic prostatitis-like symptoms. METHODS: Chronic prostatitis-like symptoms were measured by the National Institutes of Health-Chronic Prostatitis Symptom Index. Of the 28,841 men aged 20 years who lived in the study community, 18,495 men (a response rate 64.1%) agreed to participate in the study. A total of 1057 men who complained of symptoms indicative of chronic prostatitis were included in the study. The influences of pain and urinary symptoms on quality of life were determined using logistic regression analysis. The receiver operating characteristic (ROC) curve was used to estimate the predictive ability of each of these variables with respect to quality of life. RESULTS: Results from multivariate analysis showed that both pain and urinary symptoms were associated with an increased likelihood of impaired quality of life, although pain contributed more to a reduced quality of life than urinary symptoms. Relative to men who experienced mild pain, men who experienced moderate pain had a 3.9-fold risk of poor quality of life (odds ratio [OR], 3.87; 95% confidence interval [CI], 2.86-5.23; P < 0.001) and those who experienced severe pain had a 15.7-fold risk of reduced quality of life (OR, 15.68; 95% CI, 6.59-37.35; P < 0.001). Moderate urinary symptoms were associated with a 1.4-fold risk of bother (OR, 1.41; 95% CI, 1.01-1.99; P < 0.001) and severe urinary symptoms were associated with 2.4-fold risk (OR, 2.39; 95% CI, 1.37-4.12; P < 0.001), relative to mild urinary symptoms. Comparison of the effects of pain and urinary symptoms showed that pain severity had the most predictive power for bother, quality of life, and quality-of-life impact. The areas under the ROC curves for bother, quality of life, and quality-of-life impact were 71.3%, 69.3% and 72.5%, respectively. CONCLUSION: Urinary symptoms and pain might be associated with an increased likelihood of impaired quality of life in young men with chronic prostatitis-like symptoms. In addition, our findings suggest that pain severity is the most influential variable for determining quality of life in this population.  相似文献   
2.
We studied how posture influences the effects of transdermal scopolamine on autonomic cardiovascular regulation in a randomized, double-blind, placebo-controlled crossover study of 10 healthy young volunteers. We recorded the electrocardiogram and auscultatory sphygmomanometric and continuous non-invasive finger arterial pressure (Finapres device) to obtain signals for the beat-by-beat R–R interval and systolic, mean and diastolic pressures. R–R interval and arterial pressure variabilities were characterized by power spectral analysis. Scopolamine increased the mean R–R intervals and reduced arterial pressure in both the supine and the standing positions, but did not affect blood pressure variability. Scopolamine increased the total variability of R–R interval and its mid- (0·07–0·15 Hz) and high- (0·15–0·40 Hz) frequency band power in the standing position during controlled breathing at 0·25 Hz. In the supine position, scopolamine did not affect R–R interval variability. In the deep breathing test, scopolamine increased the maximal expiratory–inspiratory R–R interval ratio. This study showed that low-dose scopolamine increases vagal cardiac inhibition in both supine and standing positions in healthy volunteers. However, scopolamine increases heart rate variability only in the standing position during partial vagal withdrawal. The study also demonstrates that transdermal scopolamine decreases blood pressure in healthy young subjects.  相似文献   
3.
The effect of different tissue prehandling methods on the phenolic content of willow bark, leaves, and twigs was studied. The phenolics were extracted at room temperature, purified, and analyzed by high resolution capillary gas chromatography. Neither oven-drying at a low temperature nor room-drying of fresh leaves and oven-drying of bark produced any qualitative changes in the glucoside composition and only a minor binding effect was seen on the amounts of each glucoside. On the other hand, oven-drying of the intact long twigs and room-drying of the bark are prehandling methods to avoid. Freeze-drying or immediate analysis of frozen leaves lowered the total amount of glucosides and caused considerable qualitative changes to the glucoside composition. 80% acetone was found to be slightly more effective and gentle extraction solvent for all glucosides compared with methanol.  相似文献   
4.
Delayed Enhancement of Acetaminophen Hepatotoxicity by GeneralAnesthesia Using Diethyl Ether or Halothane. WELLS, P. G., RAMJI,P., AND KU, M. S. W. (1986). Fundam. App. Toxicol 6, 299–306.Acetaminophen (Tylenol) is a widely used analgesic/antipyreticdrug which is enzymatically bioactivated, or toxified, by thecytochromes P-450 to a hepatotoxic reactive intermediary metabolite.Brief general anesthesia with diethyl ether has been shown toinhibit both the toxifying cytochromes P-450 and enzymatic glucuronidation,the latter constituting up to 60% of acetaminophen eliminationvia a nontoxifying pathway. Thus ether potentially could producea temporally differentiated inhibition of bioactivating and"detoxifying" pathways, resulting in an enhancement of acetaminophenhepatotoxicity if the balance favored bioactivation. To evaluatethis possibility, separate groups of male NIH strain mice weretreated with acetaminophen at different times after 5 min ofanesthesia with ether. Ether produced a 40-fold enhancementin acetaminophen hepatotoxicity as determined by plasma glutamic-pyruvictransaminase (GPT) concentrations. This toxicologic enhancementwas observed only if acetaminophen administration was delayed,with a maximal enhancement when acetaminophen was given 6 hrafter ether, and no effect with a delay of 16 hr. Similar studiesin male CD-1 mice were carried out using halothane (Fluothane)as the general anesthetic given either over 5 min or over 1hr. While halothane given over 5 min had no effect, a 1 hr anestheticduration produced a 10-fold increase in acetaminophen hepatotoxicityas determined by peak GPT concentration, with no observed hepatotoxicityin the halothane controls. Toxicologic enhancement occurredonly with delayed administration of acetaminophen; however,the maximal enhancement observed with a 6-hr delay was stillevident with a 12-hr delay. Conversely, inhibition of acetaminophenhepatotoxicity was observed if acetaminophen was given either2 hr or 18 hr after halothane. These observations may have clinicalrelevance, and they indicate potential complications in theinterpretation of results obtained from animals subjected togeneral anesthesia.  相似文献   
5.
【目的】 分析母语非英语国家科技期刊出版策略,为国内期刊国际化发展提供借鉴。【方法】 以巴西SciELO平台为例,通过文献调研、平台调研、双语期刊案例调研等方法剖析巴西期刊出版策略。【结果】 作为国际上首个开放出版平台,SciELO平台更多是面向本国期刊质量提升与评估优化、数字化出版、出版语种平衡及国际影响力提升需要而提出的发展策略。【结论】 SciELO平台本身就是一种国际化策略,发挥了“造船出海“的功能,对整体提升巴西期刊国际影响力具有非常重要的作用,其数字出版平台的牵引作用和语种的平衡发展方式值得我国借鉴。  相似文献   
6.
睡眠有3种成分:浅睡眠、慢波睡眠(slowwavesleep,SWS)和快眼动睡眠。提出催眠药物开发新构想,即SWS是最重要的睡眠成分,选择性增加深睡眠的催眠药物最重要,它将对改善失眠,辅助治疗焦虑症、抑郁症和痴呆症具有重要意义。近十年研究进展包括:(1)腹外侧视前区结节乳头体可能是睡眠觉醒的中枢发生部位。基底前脑吻端pGD2敏感性睡眠促进区参与睡眠调节;(2)生长激素释放激素、褪黑激素、pGD2、IL1和腺苷均可增加SWS。本系神经药理研究室关于SWS的研究工作包括:(1)建立起家兔和大鼠睡眠成分自动分析系统(autoanalysissleepingstagessystems,ASS);(2)利用ASS研究了免疫增强剂如转移因子、胞壁酰二肽、肿瘤坏死因子,以及5HT1A受体激动剂和5HT2受体拮抗剂对睡眠成分的影响;(3)探讨5HT1A受体、REM睡眠和5HT2受体间的关系。近十年睡眠调节的研究进展证明“构想”的可行性和正确性,并提示,在中枢可能存在免疫增强TNF增多5HT更新率增加SWS途径。激动5HT1A自身受体与拮抗5HT2受体有类似效果,二者间有协同作用。开发选择性延长  相似文献   
7.
目的以反相高效液相色谱法(RP-HPLC)测定甘露药浴颗粒(外用)中盐酸麻黄碱的含量。方法色谱柱:WatersC18(150mm×4.6mm);流动相:水-乙烷-十二烷基硫酸钠-磷酸(650∶350∶5∶1);流速:1.0mL/min;柱温:26℃;检测波长:210nm。结果该方法的线性范围为0.127~0.130μg/μL(r=0.9996,n=5),平均回收率为99.72%,RSD=1.12%。结论本法简便、准确、重现性好,可用于该制剂的质量控制。  相似文献   
8.
OBJECTIVE--To examine the relationship between baroreflex sensitivity and neurohormonal activation in patients with an acute myocardial infarction. METHODS--Baroreflex sensitivity, plasma noradrenaline, atrial natriuretic factor, endothelin-1, and plasma renin activity were measured in 37 male patients about 10 days after their first myocardial infarction, and in 15 healthy controls. Baroreflex sensitivity was assessed from the regression line relating the change in RR interval to the change in systolic blood pressure following an intravenous bolus injection of phenylephrine. The measurements were repeated after a follow up of three months. RESULTS--There was a significant inverse correlation between baroreflex sensitivity and plasma noradrenaline measured before hospital discharge (r = -0.43, P < 0.01). Patients with increased plasma noradrenaline (> or = 2SD above the mean of the age matched control group) had significantly lower baroreflex sensitivity than patients with normal plasma noradrenaline (8.7 (SD 4.6) v 12.1 (6.1) ms/mm Hg, P < 0.05). The change in baroreflex sensitivity during the follow up showed a significant inverse correlation with the change of plasma noradrenaline (r = -0.450, P < 0.01). Furthermore, when patients with increased plasma noradrenaline before hospital discharge were analysed separately, baroreflex sensitivity at three months in patients in whom plasma noradrenaline had decreased to normal values was significantly higher than in patients in whom plasma noradrenaline had remained increased (14.6 (5.7) v 8.1 (8.1) ms/mm Hg, P < 0.05). On the other hand, baroreflex sensitivity was not related to the levels of plasma atrial natriuretic factor, plasma endothelin-1, or plasma renin activity. Neither was any relationship found between change in baroreflex sensitivity and change in plasma atrial natriuretic factor, endothelin-1, or plasma renin activity during the follow up. CONCLUSIONS--The impairment baroreflex sensitivity after myocardial infarction was associated with increased concentration of plasma noradrenaline, that is, sympathetic activation, but not with plasma atrial natriuretic factor, endothelin-1, or plasma renin activity. Baroreflex sensitivity provides information about cardiac vagal control as well as about the balance of cardiac sympathetic-parasympathetic regulation.  相似文献   
9.
10.
The change in augmentation index following salbutamol inhalation has been applied to evaluate endothelial function. We examined the contribution of salbutamol‐induced increase in heart rate to the observed decrease in augmentation index. Haemodynamics were recorded using whole‐body impedance cardiography and continuous pulse wave analysis from tonometric radial blood pressure. All subjects (n = 335, mean age 46, body mass index 26, 48% men) were without medications with cardiovascular influences. The effects of salbutamol inhalation (0.4 mg) versus the endothelium‐independent agent nitroglycerin resoriblet (0.25 mg) were examined during passive head‐up tilt, as the haemodynamic influences of these compounds depend on body position. Salbutamol decreased augmentation index by ~3‐4% units in supine and upright positions. Although salbutamol moderately increased cardiac index (+4.5%) and decreased systemic vascular resistance (?8.5%), the significant haemodynamic explanatory factors for decreased augmentation index in multivariate analysis were increased supine heart rate, and increased upright heart rate and decreased ejection duration (< 0.001 for all, r= 0.36–0.37). Sublingual nitroglycerin decreased supine and upright augmentation index by ~15% units and ~23% units, respectively. The haemodynamic explanatory factors for these changes in multivariate analysis were increased heart rate, reduced ejection duration and reduced systemic vascular resistance ( 0.021 for all, r2 = 0.22–0.34). In conclusion, the lowering influence of salbutamol on augmentation index may be largely explained by increased heart rate, suggesting that this effect may not predominantly reflect endothelial function.  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