首页 | 官方网站   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   696篇
  免费   39篇
  国内免费   5篇
医药卫生   740篇
  2023年   2篇
  2022年   4篇
  2021年   19篇
  2020年   7篇
  2019年   14篇
  2018年   24篇
  2017年   11篇
  2016年   22篇
  2015年   21篇
  2014年   37篇
  2013年   51篇
  2012年   54篇
  2011年   39篇
  2010年   25篇
  2009年   25篇
  2008年   33篇
  2007年   36篇
  2006年   39篇
  2005年   38篇
  2004年   30篇
  2003年   29篇
  2002年   21篇
  2001年   16篇
  2000年   12篇
  1999年   11篇
  1998年   6篇
  1997年   3篇
  1996年   5篇
  1995年   4篇
  1994年   8篇
  1993年   4篇
  1992年   6篇
  1991年   10篇
  1990年   8篇
  1989年   7篇
  1988年   5篇
  1987年   6篇
  1986年   8篇
  1985年   2篇
  1979年   2篇
  1978年   2篇
  1977年   4篇
  1976年   2篇
  1975年   3篇
  1974年   6篇
  1973年   2篇
  1968年   2篇
  1967年   3篇
  1965年   1篇
  1961年   2篇
排序方式: 共有740条查询结果,搜索用时 31 毫秒
71.
Cognitive effects of nicotine in humans: an fMRI study   总被引:13,自引:0,他引:13  
To elucidate the neural correlates of cognitive effects of nicotine, we examined behavioral performance and blood oxygenation level-dependent regional brain activity, using functional magnetic resonance imaging, during a parametric "n-back" task in healthy nonsmoking males after the administration of nicotine (12 microg/kg body weight) or saline. Nicotine, compared to placebo, improved accuracy (P = 0.008) in all active conditions (2%-11%), and had a load-specific effect on latency (P = 0.004; 43.78% decrease at the highest memory load). Within a network of parietal and frontal areas activated by the task (P < 0.05, corrected at the voxel level), nicotine produced an increased response (P < 0.05; uncorrected within the regions of interest) in the anterior cingulate, superior frontal cortex, and superior parietal cortex. It also produced an increased response in the midbrain tectum in all active conditions and in the parahippocampal gyrus, cerebellum, and medial occipital lobe during rest (P = 0.05; uncorrected). The present observations point to altered neuronal activity in a distributed neural network associated with on-line task monitoring and attention and arousal systems as underlying nicotine-related enhancement of attention and working memory in human subjects.  相似文献   
72.
We measured the circulating levels of atrial natriuretic peptide (ANP) in 62 patients with untreated uncomplicated essential hypertension and in 30 normotensive subjects. In the hypertensive patients, mean systolic and diastolic blood pressures were 148 and 101 mm Hg, respectively, and the mean heart rate was 73 beats/min. ANP concentrations were not elevated in the hypertensive group but were actually decreased slightly over those of the control group (27.4 +/- 1.8 pg/ml versus 35.3 +/- 2.4 pg/ml [P less than 0.02]). No relationship was found between ANP levels and diastolic blood pressure, plasma renin activity, urinary sodium excretion, or serum creatinine level. In 8 of the 62 patients with essential hypertension, 6 weeks of treatment with a dihydropyridine calcium channel blocker, nitrendipine, significantly reduced plasma ANP levels from 28.6 +/- 4.3 pg/ml to 18.7 +/- 1.8 pg/ml (P less than 0.05). In 17 additional patients treated with the hypotensive agent ketanserin, ANP levels were not significantly reduced after treatment. Thus, this study demonstrates that circulating plasma ANP levels are not increased but are slightly decreased in patients with uncomplicated essential hypertension in comparison with normotensive subjects. Furthermore, antihypertensive treatment with a calcium channel antagonist reduced plasma levels of ANP.  相似文献   
73.
Hematopoietic cell transplantation (HCT) is a potentially curative treatment for children and adults with malignant and nonmalignant diseases. Despite increasing survival rates, long-term morbidity after HCT is substantial. Neurocognitive dysfunction is a serious cause of morbidity, yet little is known about neurocognitive dysfunction after HCT. To address this gap, collaborative efforts of the Center for International Blood and Marrow Transplant Research and the European Society for Blood and Marrow Transplantation undertook an expert review of neurocognitive dysfunction after HCT. In this review we define what constitutes neurocognitive dysfunction, characterize its risk factors and sequelae, describe tools and methods to assess neurocognitive function in HCT recipients, and discuss possible interventions for HCT patients with this condition. This review aims to help clinicians understand the scope of this health-related problem, highlight its impact on well-being of survivors, and help determine factors that may improve identification of patients at risk for declines in cognitive functioning after HCT. In particular, we review strategies for preventing and treating neurocognitive dysfunction in HCT patients. Finally, we highlight the need for well-designed studies to develop and test interventions aimed at preventing and improving neurocognitive dysfunction and its sequelae after HCT.  相似文献   
74.
Previous studies across species have established that the aging process adversely affects certain memory‐related brain regions earlier than others. Behavioral tasks targeted at the function of vulnerable regions can provide noninvasive methods for assessing the integrity of particular components of memory throughout the lifespan. The present study modified a previous task designed to separately but concurrently test detailed memory for object identity and spatial location. Memory for objects or items is thought to rely on perirhinal and lateral entorhinal cortices, among the first targets of Alzheimer's related neurodegeneration. In line with prior work, we split an aged adult sample into “impaired” and “unimpaired” groups on the basis of a standardized word‐learning task. The “impaired” group showed widespread difficulty with memory discrimination, whereas the “unimpaired” group showed difficulty with object, but not spatial memory discrimination. These findings support the hypothesized greater age‐related impacts on memory for objects or items in older adults, perhaps even with healthy aging. © 2015 Wiley Periodicals, Inc.  相似文献   
75.
SUMMARY A new amoxycillin/clavulanate regimen (‘Augmentin-Duo’ 400/57), to be given orally in two divided doses, has been proposed to overcome the inconvenience of tid dosing. This observer-blind, multicentre study randomised children aged two to 12 years with lower respiratory tract infection to seven days' treatment with either amoxycillin/clavulanate bid at a dose of 25/3.6mg/kg/day (221 patients) or the currently prescribed amoxycillin/clavulanate regimen of 20/5mg/kg/day tid (216 patients). Clinical success (cure) rates at follow up were 81.0% for the bid group and 77.8% for the tid group [difference 3.2%; 95% CI (-4.36, 10.80)], indicating that the regimens were of equivalent efficacy. Both regimens were well tolerated, and there was no statistically significant difference in the incidence of adverse experiences between the two groups. Compliance with study medication was high and similar for both groups (80% compliance: bid 90.0%; tid 87.0%).  相似文献   
76.
Is a published research paper an important indicator of successful operational research at programme level in low‐income countries? In academia, publishing in peer‐reviewed scientific journals is highly encouraged and strongly pursued for academic recognition and career progression. In contrast, for those who engage in operational research at programme level, there is often no necessity or reward for publishing the results of research studies; it may even be criticized as being an unnecessary detraction from programme‐related work. We present arguments to support publishing operational research from low‐income countries; we highlight some of the main reasons for failure of publication at programme level and suggest ways forward.  相似文献   
77.
Previous research in schizophrenia has not consistently found concurrent validity between researcher-rated and self-report scales of insight. Differences in the correlations between the two types of scales have been found when order of administration is varied. The current study sought to replicate this earlier study in a sample of 21 patients with chronic schizophrenia who were given the same researcher-rated scale (Scale to Assess Unawareness of Mental Disorder; SUMD) and a different self-report measure (Self-Appraisal of Illness Questionnaire; SAIQ). A counterbalanced research design was employed. Significant correlations (p < 0.05) were found between the SUMD and SAIQ subscales in the SAIQ first group but not in the SUMD first group. The present study replicated earlier findings and provides further support for the importance of order of administration effects when evaluating concurrent validity between different types of insight scales. The reliability of insight scales may be substantially improved if a self-report insight scale is administered prior to a researcher-rated scale.  相似文献   
78.
Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive immune disorder, characterized by fever, hepatosplenomegaly, pancytopenia, hypertriglyceridemia, hypofibrinogenemia, markedly elevated levels of inflammatory cytokines, and impaired cytotoxic activity of lymphocytes. FHL is often fatal in early infancy. Histologic features include organ infiltration by activated macrophages and lymphocytes. Four genetic loci (FHL1, 2, 3, and 4) have been identified, of which FHL2 involves mutations in the perforin gene and is present in 20-50% of patients with FHL. We herein report the first comprehensive molecular analysis of 16 unrelated cases of FHL in ethnic Omanis. Using direct DNA sequencing analysis in 11 families, seven different mutations were identified in the coding region of the perforin gene, of which five were novel. Perforin gene defects do not seem to be involved in one-third of the cases of FHL in ethnic Omanis.  相似文献   
79.
80.
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-23

京公网安备 11010802026262号