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   9555篇
  免费   579篇
  国内免费   53篇
耳鼻咽喉   105篇
儿科学   142篇
妇产科学   77篇
基础医学   1363篇
口腔科学   152篇
临床医学   942篇
内科学   2059篇
皮肤病学   228篇
神经病学   1080篇
特种医学   516篇
外科学   1266篇
综合类   50篇
一般理论   15篇
预防医学   594篇
眼科学   148篇
药学   739篇
中国医学   36篇
肿瘤学   675篇
  2023年   52篇
  2022年   107篇
  2021年   234篇
  2020年   142篇
  2019年   196篇
  2018年   220篇
  2017年   166篇
  2016年   211篇
  2015年   262篇
  2014年   353篇
  2013年   460篇
  2012年   693篇
  2011年   732篇
  2010年   421篇
  2009年   400篇
  2008年   651篇
  2007年   665篇
  2006年   568篇
  2005年   561篇
  2004年   503篇
  2003年   439篇
  2002年   422篇
  2001年   111篇
  2000年   124篇
  1999年   113篇
  1998年   103篇
  1997年   75篇
  1996年   56篇
  1995年   56篇
  1994年   34篇
  1993年   46篇
  1992年   55篇
  1991年   46篇
  1990年   51篇
  1989年   61篇
  1988年   48篇
  1987年   49篇
  1986年   54篇
  1985年   38篇
  1984年   46篇
  1983年   30篇
  1982年   44篇
  1981年   38篇
  1980年   37篇
  1979年   29篇
  1978年   36篇
  1977年   20篇
  1976年   20篇
  1975年   22篇
  1973年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Background/PurposeThe surgical treatment for patients with progressive familial intrahepatic cholestasis (PFIC) is either liver transplantation (LTX) or partial external biliary diversion (PEBD). Both procedures achieve a good short-term outcome. However, the treatment strategy for these children remains controversial because the long-term outcome after PEBD is unknown. The aim of our study was to assess the long-term outcome and complications after PEBD in our institution.MethodsWe retrospectively analyzed the characteristics of all patients with PFIC undergoing PEBD in our department from 1994 to 2008. The course of serum bile acids, pruritus, and liver enzymes was assessed in a regular follow-up.ResultsTwenty-four patients underwent PEBD. Thirteen patients (54%) improved significantly, with a normalization of serum bile acids (P < .001 vs postoperatively) and lessened pruritus (P < .05 vs preoperatively) at 12 months after PEBD. None of these patients showed progression of cholestasis during a median follow-up of 9.8 years (range, 1.6-14.3 years). Partial external biliary diversion failed to normalize bile acids in 11 patients, of whom 9 required secondary LTX at a 1-year follow-up, with a median interval of 1.9 years (range, 0.5-3.8 years). All 7 patients (100%) with liver cirrhosis at the time of PEBD and 2 of 17 patients without cirrhosis (12%) required secondary LTX (P < .001).ConclusionsClinical improvement with normalization of serum bile acids within 1 year was associated with an excellent long-term outcome in patients with PEBD. The presence of liver cirrhosis at the time of PEBD indicated an unfavorable outcome. Thus, we recommend primary LTX only in PFIC patients with liver cirrhosis.  相似文献   
82.
Abstract We previously conducted a survey to gather the opinions and perspectives of scientific and clinical researchers on what levels of preclinical evidence were needed to justify translating a promising neuroprotective or neuroregenerative therapy in spinal cord injury (SCI) into a human clinical trial (Kwon et al., 2010 ). Here we conducted an analogous survey of individuals living with SCI in which we gathered their expectations for the levels of preclinical evidence achieved by researchers in substantiating the neuroprotective and neuroregenerative therapies being offered to them in clinical trials. In total, 214 individuals with SCI completed the survey, and their responses were compared to the responses of the 235 scientists and clinicians who completed our previous survey. SCI individuals were more likely than SCI researchers to opine that demonstrating efficacy and safety in rodent models of SCI alone is sufficient to proceed with clinical trials. However, SCI individuals also reported strong support for large animal and primate model studies, and in the case of the latter, were actually more in agreement for the need for primate studies than researchers. SCI individuals also reported strong support for independent replication studies. In general, individuals with SCI had high expectations for the levels of preclinical evidence required to justify translating novel therapies into clinical trials. These expectations should be considered in the decisions to translate specific experimental therapies for SCI.  相似文献   
83.
Background: Remifentanil-induced secondary hyperalgesia has been documented experimentally in both animals and healthy human volunteers, but never clinically. This study tested the hypotheses that increased pain sensitivity assessed by periincisional allodynia and hyperalgesia can occur after relatively large-dose intraoperative remifentanil and that small-dose ketamine prevents this hyperalgesia.

Methods: Seventy-five patients undergoing major abdominal surgery were randomly assigned to receive (1) intraoperative remifentanil at 0.05 [mu]g [middle dot]kg-1 [middle dot]min-1 (small-dose remifentanil); (2) intraoperative remifentanil at 0.40 [mu]g [middle dot]kg-1 [middle dot]min-1 (large-dose remifentanil); or (3) intraoperative remifentanil at 0.40 [mu]g [middle dot]kg-1 [middle dot]min-1 and 0.5 mg/kg ketamine just after the induction, followed by an intraoperative infusion of 5 [mu]g [middle dot] kg-1 [middle dot] min-1 until skin closure and then 2 [mu]g [middle dot]kg-1 [middle dot]min-1 for 48 h (large-dose remifentanil-ketamine). Pain scores and morphine consumption were recorded for 48 postoperative hours. Quantitative sensory tests, peak expiratory flow measures, and cognitive tests were performed at 24 and 48 h.

Results: Hyperalgesia to von Frey hair stimulation adjacent to the surgical wound and morphine requirements were larger (P < 0.05) and allodynia to von Frey hair stimulation was greater (P < 0.01) in the large-dose remifentanil group compared with the other two groups, which were comparable. There were no significant differences in pain, pressure pain detection threshold with an algometer, peak flow, cognitive tests, or side effects.  相似文献   

84.
Growth retardation is a serious side effect of long-term glucocorticoid (GC) treatment. In order to prevent or diminish this deleterious effect, a combination therapy including growth hormone (GH), a stimulator of bone growth, is often recommended. Parathyroid hormone (PTH) and thyroid hormone (T4) are important hormonal regulators of bone growth, and might also be helpful anabolic agents for counteracting the negative effects of GCs. Therefore, we studied the interaction of GCs in combination with a single dose of either PTH or T4 on GC-induced growth retardation. Dexamethasone (Dex) treatment of mice for four weeks induced a significant growth inhibition of body length and weight and weights of several organs. PTH or T4 alone did not affect the normal growth pattern. However, T4 could partially restore the Dex-induced growth inhibition, whereas PTH could not. Although PTH did not affect total body growth, it did affect the height of the proliferative zone, which could be counteracted by Dex. This contrasts with T4 treatment alone or in combination with Dex, which both resulted in a disturbed morphology of the growth plate. IGF-I mRNA, one of the mediators of longitudinal bone growth, was present in proliferative and hypertrophic chondrocytes. However, its expression was not affected by any of the treatments. In conclusion, T4 but not PTH can partially counteract the effects of Dex on general body growth, with possible implications for future treatments of GC-induced growth retardation. Additionally, both T4 and PTH, alone or in combination with Dex, have differential effects on the morphology of the growth plate.This work was presented in part at the IPNA Seventh Symposium on Growth and Development in Children with Chronic Kidney Disease: The Molecular Basis of Skeletal Growth, 1–3 April 2004, Heidelberg, Germany  相似文献   
85.
OBJECT: In contrast to conventional anastomosis methods, the excimer laser-assisted nonocclusive anastomosis (ELANA) technique involves a platinum ring and intima-adventitia apposition with a rim of medial and adventitial layers exposed to the bloodstream. The authors assessed the reendothelialization of porcine carotid arteries through ELANA compared with conventional anastomosis by using scanning electron microscopy. METHODS: In 28 pigs a bypass with one ELANA and one conventional anastomosis was made on the left common carotid artery. All patent anastomoses were evaluated intraoperatively with the aid of an ultrasonographic flowmeter and postoperatively by using scanning electron microscopy at 2 weeks, 2 months, 3 months, and 6 months thereafter. Twenty-four of 28 bypasses (48 of 56 end-to-side anastomoses) were fully patent at the time of evaluation. On scanning electron microscopic evaluation of the bypasses, all 48 patent anastomoses showed complete reendothelialization, including all 24 ELANAs in which the endothelium covered the rim and the laser-ablated edge completely. No endothelial difference was observed between conventional anastomoses and ELANAs, aside from the obvious anatomical differences like the platinum ring, which had been completely covered with endothelium. At 6 months postsurgery, remodeling of the ELANA was observed, leaving the ring covered with a layer of endothelium as the most narrow part of the anastomosis. CONCLUSIONS: In long-term experiments, ELANA allows reendothelialization comparable to that achieved with conventional anastomosis. Considering its nonocclusive and high-flow characteristics, the ELANA technique is preferable in cerebral revascularization procedures.  相似文献   
86.
BACKGROUND: Acute renal failure (ARF), requiring dialysis (ARF-d), develops in 1-5% of patients undergoing cardiac surgery and is associated with higher in-hospital mortality. Age is one of the known risk factors for the development of ARF. As the ageing population is increasing, the nephrologist will be faced with a large population of elderly patients requiring dialysis following cardiac surgery. The aim of our study was to evaluate the influence of age on and the risk factors for in-hospital mortality. METHODS: Eighty-two patients with ARF following cardiac surgery and requiring dialysis between January 1997 and October 2001 were included. Two groups of patients were studied: the younger population (<70 years, 42 patients, mean age 59+/-10) and an elderly population (>/=70 years, 40 patients, mean age 76+/-4). Severity of disease was evaluated using the SAPS (Simplified Acute Physiology Score), the Liano score and the SHARF (Stuivenberg Hospital Acute Renal Failure) score. RESULTS: Overall mortality in the population with ARF-d was 56.1%. No difference in mortality rate was found between the younger (61.9%) and elderly patient group (50.0%). The two groups were very similar in baseline and procedural characteristics with exception of body weight (P=0.02) and preoperative glomerular filtration rate (P=0.0001). No significant difference was found in the scoring systems between the old and the young (SAPS P=0.52; Liano P=0.96; SHARF T0 P=0.06; SHARF T48 P=0.15). Mortality in the elderly was significantly correlated with hypotension before starting renal replacement therapy (RRT) (P=0.002), mechanical ventilation (P=0.002), presence of multiorgan failure (MOF) (P=0.0001) and higher scores in the severity models (SAPS: P=0.01; Liano: P<0.0001 and SHARF: P<0.0001). CONCLUSION: The outcome in the elderly requiring dialysis due to ARF post-cardiac surgery is comparable with the outcome in a younger population. No significant difference was found in severity of disease between the elderly and the younger. Variables predicting mortality in the elderly are the presence of MOF, mechanical ventilation and hypotension 24 h before starting RRT. These findings indicate that at the time the nephrologist is called for an elderly patient requiring dialysis due to ARF following cardiac surgery, age per se is not a reason to withhold RRT.  相似文献   
87.
BACKGROUND: Ageing is associated with a progressive loss of renal mass and kidney length and a decline in glomerular filtration rate (GFR). This study evaluated a possible correlation between renal function and kidney size measured by ultrasonography (US), and whether the latter helps estimate GFR in the elderly. METHODS: Twenty-five medically stable elderly patients (mean age 85 +/- 5 yrs) were examined in a geriatric ward at a university hospital. Blood samples were taken to determine serum creatinine (Cr) levels. On the same day, 51chromium ethylenediamine tetraacetic acid (51Cr-EDTA) clearance was performed as the gold standard of GFR. US measured kidney length, transverse and anteroposterior dimensions. RESULTS: Serum Cr (r=-0.67; p=0.0002), Cockcroft-Gault formula (r=0.82; p<0.0001), absolute length (r=0.51; p=0.008) and volume kidney (r=0.46; p=0.02) correlated significantly with GFR. After receiver operating curve (ROC) analysis, length was less specific than sensitive in detecting renal impairment. Adding length to the Cockcroft-Gault formula did not improve GFR estimation (p=0.44). In contrast, adding length to serum Cr levels improved GFR estimation (p=0.015). CONCLUSION: In the elderly, kidney length and volume significantly correlated with GFR. However, length has a low specificity in predicting renal impairment. Therefore, in clinical practice, serum Cr levels and calculated Cr clearance are more useful in predicting renal impairment. However, normal kidney length can help to exclude renal impairment in the elderly at risk of GFR underestimation by a calculated Cr clearance.  相似文献   
88.
89.
The Karasek Job Demand–Control model has as its central tenet the so‐called ‘strain hypothesis’, stating that the most adverse health outcomes are to be expected in ‘high strain’ jobs characterized by high job demands and low job control. Later, this model was elaborated, stating that ‘isolated’ high strain workers experiencing low worksite social support are even more worse off. This is labelled the ‘iso‐strain hypothesis’. However, in the literature, the question was raised whether a high level of job control may (1) mitigate or buffer the effects of high job demands on psychological well‐being, or alternatively whether (2) a high level of social support may buffer the negative impact of high strain on psychological well‐being. In this study among 16 335 male workers and 5084 female workers in Belgium, four indicators of psychological well‐being are considered: feelings of depression, feelings of fatigue, sleep problems and use of psychoactive drugs. Both in men and in women, the general strain hypothesis and the iso‐strain hypothesis alike are corroborated regarding the cross‐sectional associations adjusted for age, level of education and living situation. This is most clear with respect to feelings of depression, less so with respect to the use of psychotropic drugs. The buffer hypotheses however are definitely not supported by our data. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
90.
The main objective of this study was to examine the psychosocial stress model developed by Taylor and Aspinwall with emotional exhaustion as the outcome variable. Respondents, 409 men and 346 women, who had a paid job for at least 20 hours per week, completed questionnaires concerning demographic variables, personality, temperament, work pressure, workload, perceived social support, appraisal, coping, and emotional exhaustion. Structural equation analyses provided only partial support for the validity of the model. First, on theoretical and statistical grounds, one more path linking external resources to social support was added. Second, contrary to expectations, coping styles did not predict emotional exhaustion. To conclude, when coping is measured retrospectively, it does not add to our understanding of emotional exhaustion. It is suggested that future studies should be longitudinal and include objective measures of stressors and psychosocial health outcomes in addition to self‐reports. Copyright © 2007 John Wiley & Sons, Ltd.  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