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   1381篇
  免费   79篇
  国内免费   11篇
耳鼻咽喉   7篇
儿科学   22篇
妇产科学   27篇
基础医学   175篇
口腔科学   3篇
临床医学   104篇
内科学   442篇
皮肤病学   22篇
神经病学   204篇
特种医学   23篇
外科学   115篇
综合类   4篇
预防医学   108篇
眼科学   4篇
药学   91篇
肿瘤学   120篇
  2024年   3篇
  2023年   26篇
  2022年   47篇
  2021年   53篇
  2020年   42篇
  2019年   43篇
  2018年   51篇
  2017年   34篇
  2016年   52篇
  2015年   55篇
  2014年   57篇
  2013年   81篇
  2012年   121篇
  2011年   94篇
  2010年   53篇
  2009年   51篇
  2008年   86篇
  2007年   85篇
  2006年   86篇
  2005年   78篇
  2004年   82篇
  2003年   63篇
  2002年   57篇
  2001年   5篇
  2000年   5篇
  1999年   8篇
  1998年   10篇
  1997年   2篇
  1996年   1篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   4篇
  1979年   2篇
  1978年   2篇
  1977年   4篇
  1974年   3篇
  1973年   1篇
  1972年   1篇
排序方式: 共有1471条查询结果,搜索用时 0 毫秒
11.
Several genes with an essential role in the regulation of eating behavior and body weight are considered candidates involved in the etiology of eating disorders (ED), but no relevant susceptibility genes with a major effect on anorexia nervosa (AN) or bulimia nervosa (BN) have been identified. Brain-derived neurotrophic factor (BDNF) has been implicated in the regulation of food intake and body weight in rodents. We previously reported a strong association of the Met66 allele of the Val66Met BDNF variant with restricting AN (ANR) and low minimum body mass index in Spanish patients. Another single nucleotide polymorphism located in the promoter region of the BDNF gene (-270C>T) showed lack of association with any ED phenotype. In order to replicate these findings in a larger sample, we performed a case-control study in 1142 Caucasian patients with ED consecutively recruited in six different centers from five European countries (France, Germany, Italy, Spain and UK) participating in the 'Factors in Healthy Eating' project. We have found that the Met66 variant is strongly associated to all ED subtypes (AN, ANR, binge-eating/purging AN and BN), and that the -270C BDNF variant has an effect on BN and late age at onset of weight loss. These are the first two variants associated with the pathophysiology of ED in different populations and support a role for BDNF in the susceptibility to aberrant eating behaviors.  相似文献   
12.
Record linkage was carried out between the national Registry of AIDS and 13 Cancer Registries (CRs) covering, in 1991, about 15% of the Italian population. Observed and expected numbers of cancers and standardized incidence ratios (SIRs) were assessed in 6067 persons with AIDS, for a total of 25,759 person-years. Significantly increased SIRs were found for Hodgkin''s disease [8.9, 95% confidence interval (CI) 4.4-16.0], in which seven of 11 cases were of mixed cellularity type; invasive carcinoma of the cervix uteri (15.5; 95% CI 4.0-40.1); and non-melanomatous skin cancer (3.0, 95% CI 1.3-5.9), in which five of eight cases were basal cell carcinoma. An excess was also seen for brain tumours, but this may be partly due to misdiagnosis of brain non-Hodgkin''s lymphoma or other brain diseases occurring near the time of the AIDS diagnosis. The risk for all cancer types, after exclusion of Kaposi''s sarcoma (KS) and non-Hodgkin''s lymphoma (NHL), was approximately twice the general population risk. An increased SIR for Hodgkin''s disease in persons with AIDS is thus confirmed, though it is many times smaller than that for NHL. An association with invasive carcinoma of the cervix is also shown at a population level. The excess of non-melanomatous skin cancer seems to be lower than in transplant recipients.  相似文献   
13.
OBJECTIVES: Intestinal alkaline sphingomyelinase, by exerting a major role in dietary sphingomyelin digestion, is responsible for the generation of messengers able to trigger the rapid turnover and apoptosis in intestinal epithelial cells. Markedly reduced mucosal alkaline sphingomyelinase activity has been associated with human colorectal neoplasms. The aim of this study was to analyze the alkaline sphingomyelinase activity in feces from healthy subjects and colorectal adenocarcinoma patients and to correlate it with the enzyme activity in intestinal tissues. MATERIALS AND METHODS: The enzyme activity was measured both in the intestinal samples from 12 healthy controls and 51 patients with colorectal adenocarcinoma (tumoral and paratumoral tissue) and in the fecal samples of 34 healthy subjects and 29 patients with adenocarcinoma. The relation between sphingomyelinase activity and Dukes' stage, cell differentiation degree, age, and gender was also analyzed. RESULTS: Alkaline sphingomyelinase was significantly decreased (P < 0.001; mean reduction >90%) in tumoral intestinal mucosa of patients compared with controls independently of Dukes' stage and tumor differentiation grade. Interestingly, the enzyme activity in histologically normal paratumoral tissues was statistically lower than control samples (P < 0.001). As occurs in neoplastic tissues, a relevant mean reduction (P < 0.0001; almost 90%) of alkaline sphingomyelinase was revealed in stool samples from tumor patients when compared with controls. CONCLUSION: These findings may have implications for cancer biology and perhaps also for the design of clinical test, thus suggesting that the fecal sphingomyelinase activity could really reflect the human intestinal mucosa enzyme level and could represent a new marker for human colorectal adenocarcinoma, mainly taking into account its early appearance in intestinal neoplasms.  相似文献   
14.
15.
Introduction:Most of the molybdenum (Mo) is used in metallurgical applications, the tetrathiomolybdate form is an experimental chelating agent for Wilson’s disease. Human data of acute Mo exposure are lacking and, no report of no-observed-adverse-effect level (NOAEL) has been described until now.Case study:We report a case of acute occupational exposure to molybdenum, with the related plasma and urine molybdenum concentrations, caused by an accidental ingestion of a sip of an anti-corrosion liquid for metal containing sodium molybdate. Our purpose was to evaluate potential systemic toxicity of molybdenum and to evaluate the dose-response/dose-effect relationship. We estimated the amount of ingested molybdenum to make a mg/kg relationship and performed repeated urine and plasma molybdenum determinations. The patient was hospitalized for three days to monitor possible development of acute symptoms/biochemical alterations.Discussion:We estimated the amount of the sip around 50 ml, with an estimation of a total of 5 gr of sodium molybdate that, for the patient bodyweight of 80 kg, would mean 62,5 mg/kg of ingested Mo. Blood and urine samples collected 2 hours after ingestion showed 50 mcg/L (reference range: 0.43 – 1.8 mcg/L) and 630 mcg/L (refence range: up to 116 mcg/L) of Mo respectively, confirming acute exposure. The patients remained asymptomatic confirming that an estimated oral dose of Mo of 62.5 mg/kg was not associated with adverse effects.Conclusions:Our value, being extrapolated by a single case, will require further confirmations from other studies to allow a full evaluation of a NOAEL. Nevertheless, it does not preclude its use in evaluating the probable absence of adverse effect in the context of acute Mo exposure.  相似文献   
16.
17.
BACKGROUNDMasked diastolic hypotension is a new blood pressure (BP) pattern detected by ambulatory blood pressure monitoring (ABPM) in elderly hypertensives. The aim of this study was to relate ABPM and comorbidity in a cohort of fit elderly subjects attending an outpatient hypertension clinic.METHODSComorbidity was assessed by Charlson comorbidity index (CCI) and CHA2DS2VASc score. All subjects evaluated with ABPM were aged ≥ 65 years. CCI and CHA2DS2VASc score were calculated. Diastolic hypotension was defined as mean ambulatory diastolic BP < 65 mmHg and logistic regression analysis was carried out in order to detect and independent relationship between comorbidity burden and night-time diastolic BP < 65 mmHg. RESULTSWe studied 174 hypertensive elderly patients aged 72.1 ± 5.2 years, men were 93 (53.4%). Mean CCI was 0.91 ± 1.14 and mean CHA2DS2VASc score of 2.68 ± 1.22. Subjects with night-time mean diastolic values < 65 mmHg were higher in females [54.7% vs. 45.3%, P = 0.048; odds ratio (OR) = 1.914, 95% CI: 1.047−3.500]. Logistic regression analysis showed that only CHA2DS2VASc score was independently associated with night-time mean diastolic values < 65 mmHg (OR = 1.518, 95% CI: 1.161−1.985; P = 0.002), but CCI was not. CONCLUSIONSABPM and comorbidity evaluation appear associated in elderly fit subjects with masked hypotension. Comorbid women appear to have higher risk for low ambulatory BP.

The global population is ageing, and the number of subjects with long-term disorders is increasing, with heavy consequences on medical commitment and health-care systems burden.[1] Moreover, multimorbidity is associated with a higher mortality,[2,3] and hypertension represents a frequent condition involving patients with multiple diseases.[1] The relationship between multimorbidity and hypertension is bidirectional. Hypertension could cause organ damage and then development of comorbidity; on the other hand, comorbidity could worsen hypertension and its consequences. In elderly subjects, hypertension could cause brain damage that could be the cause of cognitive decline;[4] moreover, systemic atheroembolic syndrome could worsen blood pressure (BP) variability leading to cardiovascular disease (CVD).[5]Hypertension, both complicated or not complicated, is a variable taken into consideration in a series of risk scores applied to the general population to estimate the mortality risk, such as the Cumulative Illness Rating Scale,[6] the Charlson comorbidity index (CCI),[7] and the Elixhauser index.[8] The CHA2DS2VASc score is widely used as predictor of the risk of stroke in patients with atrial fibrillation, it includes hypertension among the factors considered for score calculation and its importance is underlined by the same weight assigned to congestive heart failure (CHF), age > 75 years, and diabetes mellitus (1 point). [9] However, CHA2DS2VASc score has also been suggested to be able to stratify adverse clinical events in hypertensive patients.[10]In patients with comorbidities, out-of-office monitoring of BP has been shown to be associated with reduced systolic BP (SBP) compared to usual care, representing a very useful tool in routine clinical practice.[11] However, the discrepancy of measures between office and out-of-office BP measures, such as ambulatory blood pressure monitoring (ABPM), is known since two decades,[12] and these two approaches have pros and cons depending also on type of patients. In untreated older patients with isolated systolic hypertension, for example, ambulatory SBP was a significant predictor of cardiovascular risk over and above conventional BP.[13,14]It is widely accepted that ABPM is a crucial informative tool for the evaluation of BP behaviour in everyday clinical practice,[15] and is recommended to identify white-coat hypertension and masked hypertension.[15,16] However, its importance goes greatly beyond due to its capacity to provide information for clinical use.[15] In fact, night-time evaluation of BP is crucial to detect abnormal patterns of night-time behaviour, such as non-dipping, inverse dipping, extreme dipping and the morning surge,[17] and asleep SBP is a significant BP derived risk factor for CVD events.[18,19]Recently, a novel BP pattern defined masked diastolic hypotension, frequently found in older patients under antihypertensive treatment, has raised attention.[20] Knowledge related to clinical use of ABPM in elderly subjects is still a matter of debate, and information about BP components and circadian profiles in subjects with high comorbidity burden is scarce.[21]The aim of this study was investigate the possible relationship between the BP components (recorded by ABPM) and the comorbidity burden (assessed by means of CCI and CHA2DS2VASc score) in a cohort of fit elderly subjects attending an outpatient hypertension clinic.  相似文献   
18.
Crohn's disease (CD) is an inflammatory chronic bowel disorder; it can involve the whole gastrointestinal tract, but its localization in the ileum or colon is most common. The reference standard for the diagnosis of CD is ileocolonoscopy with histologic assessment. The reference standard for the detection of any complications is surgery. However, imaging techniques have an important role both in the detection/localization of CD and in the follow-up of CD patients. In the last few years, the technical development of ultrasound equipment, the advent of new technologies such as elastography and mostly the increased expertise of sonographers have boosted the role of bowel ultrasound in assessment of the gastrointestinal tract. In fact, bowel ultrasound is particularly attractive thanks to its widespread availability, non-invasiveness, low cost and good reproducibility, as it can be easily repeated during follow-up. The aim of this article is to provide an extensive overview of the actual role of bowel ultrasound in the detection and follow-up of patients with CD.  相似文献   
19.
Abstract

Objective: The Unified Classification System (UCS) presents itself as an evolution of the Vancouver Classification (VCS) for the evaluation of periprosthetic fractures of the proximal femur (PPF). The aim of our study was to highlight any loss of reproducibility or validity of the new classification system, compared to the previous one.

Material and methods: We tested the interobserver and intraobserver agreement using 40 PPF clinical cases. Each classifying subtype of the UCS and VCS was present in at least two cases. Six experienced hip surgeons (Senior Surgeon, SS) and 5 surgeons in training (Junior Surgeon, JS) classified the clinical cases, using VCS and UCS. The validity of both classifications was then tested with intraoperative surveys.

Results: The mean κ value for interobserver agreement for the VCS in the JS group was 0.65 and 0.81 for the SS group. The mean κ value for interobserver agreement for the UCS in the JS group was 0.63 and 0.65 for the SS group. The mean κ value for intraobserver agreement for the VCS in the JS group was 0.71 and 0.73 for the SS group. The mean κ value for intraobserver agreement for the UCS in the JS group was 0.72 and 0.7 for the SS group. Validity analysis showed a moderate agreement for the VCS and a good agreement for the UCS.

Conclusion: The UCS completes the Vancouver classification, expanding it. It is reliable, despite the increase in classification categories and number of parameters to evaluate, with a slightly higher validity.  相似文献   
20.
Archives of Women's Mental Health - The experience of motherhood is most often emotionally positive and rewarding, but for many new mothers suffering from postpartum depression (PPD), this is...  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