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   5631篇
  免费   484篇
  国内免费   12篇
耳鼻咽喉   40篇
儿科学   225篇
妇产科学   84篇
基础医学   855篇
口腔科学   68篇
临床医学   592篇
内科学   1426篇
皮肤病学   126篇
神经病学   676篇
特种医学   362篇
外国民族医学   1篇
外科学   607篇
综合类   97篇
一般理论   1篇
预防医学   366篇
眼科学   110篇
药学   278篇
中国医学   3篇
肿瘤学   210篇
  2021年   52篇
  2020年   41篇
  2019年   71篇
  2018年   81篇
  2017年   62篇
  2016年   62篇
  2015年   83篇
  2014年   112篇
  2013年   164篇
  2012年   245篇
  2011年   270篇
  2010年   179篇
  2009年   131篇
  2008年   227篇
  2007年   218篇
  2006年   201篇
  2005年   239篇
  2004年   194篇
  2003年   190篇
  2002年   184篇
  2001年   191篇
  2000年   198篇
  1999年   168篇
  1998年   81篇
  1997年   85篇
  1996年   73篇
  1995年   70篇
  1994年   63篇
  1993年   69篇
  1992年   149篇
  1991年   133篇
  1990年   165篇
  1989年   133篇
  1988年   116篇
  1987年   111篇
  1986年   116篇
  1985年   103篇
  1984年   83篇
  1983年   62篇
  1982年   56篇
  1981年   59篇
  1980年   43篇
  1979年   79篇
  1978年   61篇
  1977年   51篇
  1976年   53篇
  1975年   41篇
  1974年   35篇
  1973年   52篇
  1970年   39篇
排序方式: 共有6127条查询结果,搜索用时 15 毫秒
991.

Aim of the study

It has recently been suggested that acute kidney injury (AKI) may strongly be influenced by post-resuscitation disease and cardiogenic shock (CS), and may not just be a consequence of cardiac arrest and time without spontaneous circulation. AKI also has been suggested as a strong independent predictor of in-hospital mortality. Therefore the present study aimed at investigating the effect of fluid management on the incidence of AKI in patients with cardiogenic shock after cardiac arrest treated by mild therapeutic hypothermia.

Methods

Fluid therapy and the incidence of acute kidney injury (AKI) was retrospectively reviewed in 51 patients with cardiogenic shock after cardiac arrest comparing patients with and without hemodynamic (PPV, SVV) and volumetric (ELWI, GEDI) monitoring.

Results

There was no significant difference in baseline or cardiac arrest characteristics between hemodynamic monitored patients and conventional monitored patients. 28 patients were monitored by standard monitoring, in 23 patients monitoring was complemented by a PICCO system. In the first 24 h of treatment the total amount of fluid was significantly higher in patients under PICCO monitoring compared to conventional monitoring (4375 ± 1285 ml vs. 5449 ± 1438 ml, p = 0.007). This was associated with a significant reduction in the incidence of AKI (RIFLE ‘I’/‘F’: PICCO-group: 1 (4.3%) vs. conventional group 8 (28.6%), p = 0.03).

Conclusion

The presented data suggest that volume therapy guided by volumetric (ELWI, GEDI) and arterial waveform derived variables (PPV, SVV) can reduce the incidence of AKI in patients with cardiogenic shock after cardiac arrest treated with mild therapeutic hypothermia.  相似文献   
992.
We have previously shown that Campylobacter jejuni strains do not produce a functional cholera toxin-like toxin (CTLT) detectable in a Chinese hamster ovary cell assay. Instead, the 53-kDa major outer membrane protein (OMP) of C. jejuni, PorA, reacts with cholera toxin (CT) antibody on immunoblots. Here, we have extended this observation to other species of Campylobacter, including C. coli, C. lari, C. fetus, C. hyointestinalis, and C. upsaliensis, the common 53-kDa OMP of which reacted with CT antibody in immunoblotting assays. There were additional reactive bands for C. fetus. As with C. jejuni, this finding may lead to the erroneous conclusion that these additional species produce a functional CTLT. However, this common cross-reactive OMP can be explored as a vaccine candidate to prevent campylobacteriosis.  相似文献   
993.
The etiology and pathogenesis of idiopathic recurrent acute pericarditis (IRAP) remain controversial standing like a bridge that crosses infectious, autoimmune and autoinflammatory pathways. Anything may cause acute pericarditis; Echo-virus, and Coxsackie are the most frequently involved viruses, Mycobacterium tuberculosis and Coxiella burnetii the most common bacteria, but in 85% of cases it remains "idiopathic". Recurrences occur in up to 20-50% of patients. An immuno-mediated pathogenesis is suggested by the presence of pro-inflammatory cytokines in pericardial fluid, the presence of antinuclear autoantibodies (ANA) in sera of the patients, the occurrence of new autoimmune diagnoses and the good response to anti-inflammatory or immunosuppressive therapy. Nonsteroidal anti-inflammatory drugs (NSAIDs) must be used at recommended dosages, till the resolution of symptoms and normalization of C-reactive protein and erythrocyte sedimentation rate. Corticosteroids should be used rarely, at low doses, with an extremely low tapering and with osteoporosis prevention. Colchicine leads to a clinically important and statistically significant benefit, reducing recurrences by 50%. The long term outcome of IRAP is good, without evidence of constriction even after a very long follow-up.  相似文献   
994.
Cannabinoid receptor activation has been shown to modulate both neurotransmission (CB(1)) and neuroinflammatory (CB(2)) responses. There are conflicting reports in the literature describing the influence of cannabinoid receptor activation on ischemic/reperfusion injury. The goal of this study was to evaluate how changing the balance between CB(1) and CB(2) activation following cerebral ischemia influences outcome. CB(1) and CB(2) expression were tested at different times after transient middle cerebral artery occlusion (MCAO) in mice by real-time RT-PCR. Animals subjected to 1 h MCAO were randomly assigned to receive different treatments: a CB(1) antagonist, a CB(2) antagonist, a CB(2) agonist, a CB(1) antagonist plus CB(2) agonist, a CB(2) antagonist plus CB(2) agonist or an equal volume of vehicle as control. Cerebral blood flow was continuously monitored during ischemia; cerebral infarction and neurological deficit were tested 24 h after MCAO. Cerebral CB(1) and CB(2) mRNA expression undertook dynamic changes during cerebral ischemia. The selective CB(1) antagonist significantly decreased cerebral infarction by 47%; the selective CB(2) antagonist increased infarction by 26% after 1 h MCAO followed by 23 h reperfusion in mice. The most striking changes were obtained by combining a CB(1) antagonist with a CB(2) agonist. This combination elevated the cerebral blood flow during ischemia and reduced infarction by 75%. In conclusion, during cerebral ischemia/reperfusion injury, inhibition of CB(1) receptor activation is protective while inhibition of CB(2) receptor activation is detrimental. The greatest degree of neuroprotection was obtained by combining an inhibitor of CB(1) activation with an exogenous CB(2) agonist.  相似文献   
995.
OBJECTIVE: This study examined whether use of complementary and alternative (CAM) therapies during the menopause transition varied by ethnicity. DESIGN: The Study of Women's Health Across the Nation is a prospective cohort study following a group of 3,302 women from five racial/ethnic groups at seven clinical sites nationwide. Using longitudinal data encompassing 6 years of follow-up, we examined trends in use of five categories of CAM (nutritional, physical, psychological, herbal, and folk) by menopause status and ethnicity. To account for potential secular trends in CAM use or availability, we also evaluated the trends in CAM use over calendar time. RESULTS: Approximately 80% of all participants had used some form of CAM at some time during the 6-year study period. White and Japanese women had the highest rates of use (60%), followed by Chinese (46%), African American (40%), and Hispanic (20%) women. Overall use of CAM therapy remained relatively stable over the study period. In general, CAM use did not seem to be strongly associated with change in menopause transition status. Use of CAM among white women did not change with transition status. Among Chinese and African American participants, we observed an increase in CAM use as women transitioned to perimenopause and a decrease in use of CAM with transition to postmenopause. Among Hispanic and Japanese women, we observed a decrease in use of CAM in early perimenopause, followed by an increase as women entered late perimenopause and a decrease as they progressed to postmenopause. Patterns of use for the five individual types of CAM varied. White women had relatively stable use of all CAM therapies through the transition. Japanese women decreased use of nutritional and psychological remedies and increased use of physical remedies as they transitioned into late perimenopause. Among African American women, use of psychological remedies increased as they progressed through menopause. CONCLUSIONS: Although CAM use did vary in some ethnic groups in relation to advancing menopause status, there was no evidence of influence of calendar time on CAM use. Patterns of CAM use during menopause are likely to be driven by personal experience, menopausal health, and access to therapies. Women's personal preferences should be taken into consideration by healthcare providers for medical decision making during menopause and throughout the aging process.  相似文献   
996.
Clozapine, risperidone, and other new "atypical" antipsychotic agents are distinguished from traditional neuroleptic drugs by having clinical efficacy with either no or low levels of extrapyramidal symptoms (EPS). Preclinical models have focused on striatal dopamine systems to account for their atypical profile. In this study, we examined the effects of clozapine and risperidone on amphetamine-induced striatal dopamine release in patients with psychotic disorders. A novel 11C-raclopride/PET paradigm was used to derive estimates of amphetamine-induced changes in striatal synaptic dopamine concentrations and patients were scanned while antipsychotic drug-free and during chronic treatment with either clozapine or risperidone. We found that amphetamine produced significant reductions in striatal 11C-raclopride binding during the drug-free and antipsychotic drug treatment phases of the study which reflects enhanced dopamine release in both conditions. There were no significant differences in % 11C-raclopride changes between the two conditions indicating that these atypical agents do not effect amphetamine-related striatal dopamine release. The implications for these data for antipsychotic drug action are discussed.  相似文献   
997.
Primary sclerosing cholangitis (PSC) is uncommon in the younger age range and bile duct brushing cytology can present unique challenges. We describe the case of a 17‐year‐old boy with a new diagnosis of PSC who presented with cholangiocarcinoma. The clinical history, endoscopic features, cytomorphologic findings, and results of UroVysion? fluorescent in situ hybridization (FISH) on the bile duct brush are described. UroVysion FISH on bile duct brushings is an ancillary study that can improve the diagnostic sensitivity for malignancy, specially in challenging cases where the cytomorphologic or clinical characteristics of the case are not typical. The occurrence of cholangiocarcinoma in young age group with PSC is uncommon, and the utilization of UroVysion FISH has been rarely described. Diagn. Cytopathol.2011; © 2011 Wiley‐Liss, Inc.  相似文献   
998.
Goedert KM, Chen P, Botticello A, Masmela JR, Adler U, Barrett AM. Psychometric evaluation of neglect assessment reveals motor-exploratory predictor of functional disability in acute-stage spatial neglect.ObjectiveTo determine the psychometric properties of 2 neglect measures, the Behavioral Inattention Test (BIT)-conventional and the Catherine Bergego Scale (CBS), in acute spatial neglect. Spatial neglect is a failure or slowness to respond, orient, or initiate action toward contralesional stimuli, associated with functional disability that impedes stroke recovery. Early identification of specific neglect deficits may identify patients likely to experience chronic disability. However, psychometric evaluation of assessments has focused on subacute/chronic populations.DesignCorrelational/psychometric study.SettingInpatient rehabilitation hospital.ParticipantsScreening identified 51 consecutive patients with a right-hemisphere stroke with left neglect (BIT score <129 or CBS score >11) tested an average of 22.3 days poststroke.InterventionsNot applicable.Main Outcome MeasuresWe obtained BIT, CBS, and Barthel Index assessments for each participant and clinical and laboratory measures of perceptual-attentional and motor-intentional deficits.ResultsThe BIT showed good reliability and loaded onto a single factor. Consistent with our theoretical prediction, principal components analysis of the CBS identified 2 underlying factors: Where perceptual-attentional items (CBS-PA) and embodied, motor-exploratory items (CBS-ME). The CBS-ME uniquely predicted deficits in activities of daily living (ADLs) assessed by using the Barthel Index, but did not predict clinical and laboratory assessments of motor-intentional bias. More severe neglect on the CBS-PA correlated with greater Where perceptual-attentional bias on clinical and laboratory tests, but did not uniquely predict deficits in ADLs.ConclusionsOur results indicate that assessments of spatial neglect may be used to detect specific motor-exploratory deficits in spatial neglect. Obtaining CBS-ME scores routinely might improve the detection of acute-stage patients with spatial action deficits requiring increased assistance that may persist to the chronic stage.  相似文献   
999.

Background

Patients present to police, Emergency Medical Services, and the emergency department with aggressive behavior, altered sensorium, and a host of other signs that may include hyperthermia, “superhuman” strength, diaphoresis, and lack of willingness to yield to overwhelming force. A certain percentage of these individuals will go on to expire from a sudden cardiac arrest and death, despite optimal therapy. Traditionally, the forensic community would often classify these as “Excited Delirium” deaths.

Objectives

This article will review selected examples of the literature on this topic to determine if it is definable as a discrete medical entity, has a recognizable history, epidemiology, clinical presentation, pathophysiology, and treatment recommendations.

Discussion

Excited delirium syndrome is characterized by delirium, agitation, acidosis, and hyperadrenergic autonomic dysfunction, typically in the setting of acute-on-chronic drug abuse or serious mental illness or a combination of both.

Conclusions

Based upon available evidence, it is the consensus of an American College of Emergency Physicians Task Force that Excited Delirium Syndrome is a real syndrome with uncertain, likely multiple, etiologies.  相似文献   
1000.
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