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   4572篇
  免费   285篇
  国内免费   27篇
耳鼻咽喉   21篇
儿科学   139篇
妇产科学   150篇
基础医学   683篇
口腔科学   44篇
临床医学   349篇
内科学   1164篇
皮肤病学   203篇
神经病学   484篇
特种医学   111篇
外科学   497篇
综合类   22篇
一般理论   2篇
预防医学   251篇
眼科学   29篇
药学   319篇
中国医学   5篇
肿瘤学   411篇
  2024年   5篇
  2023年   50篇
  2022年   123篇
  2021年   173篇
  2020年   121篇
  2019年   147篇
  2018年   132篇
  2017年   116篇
  2016年   131篇
  2015年   157篇
  2014年   206篇
  2013年   246篇
  2012年   377篇
  2011年   369篇
  2010年   183篇
  2009年   178篇
  2008年   318篇
  2007年   281篇
  2006年   238篇
  2005年   250篇
  2004年   188篇
  2003年   173篇
  2002年   117篇
  2001年   61篇
  2000年   61篇
  1999年   48篇
  1998年   30篇
  1997年   26篇
  1996年   26篇
  1995年   12篇
  1994年   11篇
  1993年   21篇
  1992年   37篇
  1991年   39篇
  1990年   29篇
  1989年   21篇
  1988年   24篇
  1987年   23篇
  1986年   23篇
  1985年   25篇
  1984年   16篇
  1983年   18篇
  1982年   4篇
  1980年   5篇
  1979年   9篇
  1978年   7篇
  1977年   3篇
  1975年   5篇
  1971年   3篇
  1970年   4篇
排序方式: 共有4884条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Magical ideation has repeatedly been shown to be related to handedness, with mixed-handers exhibiting higher levels of magical thinking. However, most previous research has assessed hand preference with a questionnaire measure, leaving open the possibility that the correlation reflects some aspect of questionnaire-taking behaviour and not an underlying neuropsychological relationship. The present study addressed this issue by administering the Magical Ideation Scale (Eckblad & Chapman, 1983), the Waterloo Handedness Questionnaire-Revised (Elias, Bryden, & Bulman-Fleming, 1998), and a manual dot-filling task (Tapley & Bryden, 1985) as a behavioural measure of handedness to an undergraduate student sample. The expected relationship between magical ideation and handedness as assessed by the questionnaire was observed. However, magical ideation was not related to the behavioural measure of handedness. Results cast doubt on a neuropsychological interpretation of the relationship between handedness and magical ideation in sub-clinical populations.  相似文献   
75.

Introduction

Discrepant data exist regarding the incidence and severity of clinical problems related to intra-hospital transport of brain-injured patients and no consensus exists whether modern-day intra-hospital transport represents a safe or potentially problematic environment for neurointensive care unit (NICU) patients.

Methods

We examined the incidence of clinical complications and physiological derangements that occurred in 160 neurologically injured patients (90 males, 70 females, mean age 57 ± 17 years) who underwent intra-hospital transport (288 cases, 237 scheduled, 51 unscheduled) for computed tomography scans.

Results

Our findings indicate that (1) at least one significant complication (predominantly hemodynamic) occurred in over one-third (36 %) of all transports (p = n.s scheduled vs. unscheduled) necessitating the deployment of interventions designed to treat changes in arterial pressure (2) despite the presence of trained medical personnel and availability of specialized equipment, intra-cranial pressure was not adequately monitored during transports (especially in patients with intra-cranial hypertension prior to transport) (3) intra-hospital transfer was associated with minor but statistically significant clinical changes, including a reduction in arterial partial pressure of oxygen ( $ {\text{Pa}}_{{{\text{O}}_{ 2} }} $ )/inspired oxygen fraction ( $ {\text{Fi}}_{{{\text{O}}_{ 2} }} $ ) (only in the scheduled transport population), decreased arterial lactate levels (scheduled transport population), lowered body temperature (scheduled transport population), and increased arterial partial pressure of carbon dioxide ( $ {\text{Pa}}_{{{\text{CO}}_{ 2} }} $ ) (scheduled transport population).

Conclusions

Intra-hospital transport of brain-injured NICU patients may present some hazards even if performed by skilled personnel with specialized equipment. In Trauma Centers such as ours, an improvement in the frequency of neuromonitoring [intra-cranial pressure (ICP) and end-tidal CO2 ( $ {\text{ET}}_{{{\text{CO}}_{ 2} }} $ )] during transport is recommended.  相似文献   
76.
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetic disorder caused by mutations in the NOTCH3 gene, with a striking variability in phenotypic expression. To date, only two homozygous patients have been reported, with divergent phenotypic features. We describe an Italian CADASIL patient, homozygous for G528C mutation, in whom early manifestation of the disease was migraine, but whose clinical evolution was characterized by a reversible acute encephalopathy followed by full recovery (“CADASIL coma”). Clinical evaluation, MR scan, neuropsychological and neurophysiological investigation did not reveal substantial differences between our homozygous patient and her heterozygous relatives sharing the same mutation, or between our patient and a group of heterozygous individuals with the same mutation but from different families. Skin biopsy identified peculiar features in the homozygous patient, with cytoplasmic pseudoinclusions likely containing granular osmiophilic material (GOM) in the vascular smooth muscle cells, but further studies are necessary to substantiate their possible relationships with CADASIL homozygosis. “CADASIL coma” did not seem to be specific of patient’s homozygosis, since it was observed in one of her heterozygous relatives, whereas its pathogenesis seems to be related to peculiar constellations of unknown predisposing factors. The present study demonstrated that CADASIL conforms to the classical definition of dominant diseases, according to which homozygotes and heterozygotes for a defect are phenotypically indistinguishable.  相似文献   
77.
PurposeThe aim of the present study is to evaluate the effect of water contamination on the shear bond strength (SBS) and adhesive remnant index (ARI) score of self-ligating brackets.Materials and methodsOne conventional bracket and three different self-ligating brackets were bonded onto 160 bovine permanent mandibular incisors, divided randomly into 8 groups. For each type of bracket, 20 samples were bonded on dry enamel and 20 after water contamination. After 24 h, all specimens were tested for SBS using an Instron Universal Testing Machine, and ARI scores were evaluated.ResultsAll groups showed clinically adequate SBSs. Quick brackets bonded onto dry enamel showed significantly higher SBSs than all other groups tested, whereas the lowest shear strength values were recorded for Step, Quick, and Damon 3MX brackets bonded onto contaminated enamel and for Damon 3MX onto dry enamel. Frequency distribution of ARI Scores showed a prevalence of ARI “2” and “3” for all the groups tested.ConclusionsWater contamination reduces the SBS of self-ligating brackets, but significant differences have been found only for Quick brackets. All groups showed a significant higher frequency of ARI Score of “2” and “3”.  相似文献   
78.
79.
80.
Background and aimsIn the field of cardiovascular diseases, elevated levels of serum uric acid (UA) reflect a marked activation of the xanthine oxidase pathway with increase in free radicals production; it is often associated with an inflammatory state, oxygen consumption and endothelial dysfunction. All these associations have been also confirmed in heart failure (HF) but the pathophysiological role of UA in this setting is not well understood. The aim of this study was to evaluate the prognostic role of UA in outpatients enrolled in the Italian Registry of Congestive Heart Failure (IN-CHF).Methods and resultsAll patients met the European Society of Cardiology (ESC) criteria for diagnosis of HF. We considered patients with complete clinical data and UA level available at the baseline and at 1-year follow-up. The study population was composed of 877 patients aged 63 ± 12 years. One-year mortality was 10.8% and dead patients had a higher level of UA than survivors (7.1 mg dl?1 vs 6.6 mg dl?1, p < 0.0207). In multivariable full model of analysis, UA did not result in an independent predictor of death in overall population, but only in patients with low body mass index (BMI) (≤22 kg m?2) (hazard ratio (HR): 2.38, 95% confidence interval (CI) 1.36–4.18). In this subgroup, a statistically significant gradual relationship between UA and survival was detected starting from values higher than 8 mg dl?1.ConclusionElevated level of UA is not an independent predictor of mortality in chronic HF, but it markedly worsens outcome if associated with low level of BMI. This association is likely an indicator of chronic inflammatory and catabolic state.  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