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   9943篇
  免费   641篇
  国内免费   70篇
耳鼻咽喉   94篇
儿科学   255篇
妇产科学   214篇
基础医学   1479篇
口腔科学   229篇
临床医学   882篇
内科学   2336篇
皮肤病学   200篇
神经病学   1134篇
特种医学   448篇
外科学   1124篇
综合类   40篇
预防医学   454篇
眼科学   214篇
药学   634篇
中国医学   42篇
肿瘤学   875篇
  2024年   15篇
  2023年   108篇
  2022年   182篇
  2021年   281篇
  2020年   166篇
  2019年   223篇
  2018年   301篇
  2017年   218篇
  2016年   241篇
  2015年   272篇
  2014年   339篇
  2013年   425篇
  2012年   677篇
  2011年   711篇
  2010年   416篇
  2009年   386篇
  2008年   612篇
  2007年   648篇
  2006年   638篇
  2005年   563篇
  2004年   566篇
  2003年   563篇
  2002年   495篇
  2001年   163篇
  2000年   148篇
  1999年   155篇
  1998年   116篇
  1997年   102篇
  1996年   89篇
  1995年   64篇
  1994年   50篇
  1993年   47篇
  1992年   62篇
  1991年   59篇
  1990年   50篇
  1989年   60篇
  1988年   54篇
  1987年   46篇
  1986年   34篇
  1985年   26篇
  1984年   28篇
  1983年   39篇
  1982年   25篇
  1979年   25篇
  1977年   14篇
  1974年   18篇
  1973年   15篇
  1972年   10篇
  1970年   12篇
  1967年   12篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Jejuno-jejunal invagination due to intestinal melanoma   总被引:1,自引:1,他引:0  
Cutaneous melanoma is one of the most studied neoplastic lesions in biology and clinical oncology. It has been well documented that this type of neoplasm presents a high metastatic rate, and is able to involve nearly every tissue. Non-cutaneous melanoma represents an unusual pattern of melanoma, and the small intestine is an uncommon anatomic localization. Herein we report an extremely rare clinical case of a young woman affected by a bleeding jejunal melanoma, whose early clinical presentation was an intestinal invagination.  相似文献   
994.
Introduction: Complex fractionated atrial electrograms (CFAE) have been described as a new target for ablation of atrial fibrillation (AF). This prospective study evaluates the acute effects of CFAE ablation in patients with paroxysmal or persistent AF and analyzes the preferential anatomic sites where these effects occur.
Methods and Results: Ablation of CFAE was performed in 66 symptomatic patients (mean age of 58 ± 12 years) with paroxysmal (n = 36) or persistent AF (n = 30). Termination or regularization of AF during ablation of CFAE was achieved in 56 of 66 patients (84%), with termination in 28 of 66 patients (42%) and regularization of AF in 28 of 66 patients (42%). Ablation of CFAE showed no effect in 10 of 66 patients (16%). Termination of AF occurred at 53 sites and AF regularization at 81 sites. The preferential sites of AF termination or regularization were found around the pulmonary veins (termination n = 15; regularization n = 22), at the anterior wall (termination n = 14; regularization n = 19) and at the interatrial septum (termination n = 8; regularization n = 17).
Conclusion: Termination or regularization of AF was achieved acutely in 84% of patients by ablation of CFAE. The preferential sites of AF termination or regularization were found around the pulmonary veins, at the anterior wall of the LA and at the interatrial septum. These findings may have implications for future ablation concepts.  相似文献   
995.
Echinacea is one of the most commonly used herbal products, but controversy exists about its benefit in the prevention and treatment of the common cold. Thus, we did a meta-analysis evaluating the effect of echinacea on the incidence and duration of the common cold. 14 unique studies were included in the meta-analysis. Incidence of the common cold was reported as an odds ratio (OR) with 95% CI, and duration of the common cold was reported as the weighted mean difference (WMD) with 95% CI. Weighted averages and mean differences were calculated by a random-effects model (DerSimonian-Laird methodology). Heterogeneity was assessed by the Q statistic and review of L'Abbé plots, and publication bias was assessed through the Egger weighted regression statistic and visual inspection of funnel plots. Echinacea decreased the odds of developing the common cold by 58% (OR 0.42; 95% CI 0.25-0.71; Q statistic p<0.001) and the duration of a cold by 1.4 days (WMD -1.44, -2.24 to -0.64; p=0.01). Similarly, significant reductions were maintained in subgroup analyses limited to Echinaguard/Echinacin use, concomitant supplement use, method of cold exposure, Jadad scores less than 3, or use of a fixed-effects model. Published evidence supports echinacea's benefit in decreasing the incidence and duration of the common cold.  相似文献   
996.
997.
Previous investigations have demonstrated impaired recognition of facial affect and cognitive dysfunction in several psychiatric disorders. The specificity of these deficits is still debated. The aim of this study was to investigate the deficits in emotion recognition and cognition in obsessive-compulsive disorder (OCD). Forty patients with OCD (DSM-IV, 16 women, 34.7+/-10.4 years) and 40 healthy volunteers (16 women, 34.7+/-8.7 years) were compared. All participants underwent a computerized neuropsychological test battery (Gur, R.C., Erwin, R.J., Gur, R.E., Zwil, A.S., Heimberg, C., Kraemer, H.C., 1992. Facial emotion discrimination II. Behavioral findings in depression. Psychiatry Research 42, 241-251; Gur, R.C., Ragland, J.D., Moberg, P.J., Turner, T.H., Bilker, W.B., Kohler, C., Siegel, S.J., Gur, R.E., 2001. Computerized neurocognitive scanning: I. Methodology and validation in healthy people. Neuropsychopharmacology 25, 766-776). A German version of the Penn Facial Emotion Acuity Test, the Facial Emotion Intensity Differentiation, including happy, sad and neutral faces, and the Facial Memory Test were administered. Executive functions were assessed by a computerized version of the Wisconsin Card Sorting Test and attention was evaluated using the Continuous Performance Test. OCD patients performed more poorly than healthy controls in facial memory tests (especially delayed), as well as in attention and executive functions. The only significant difference between the groups in emotion processing was poorer recognition of sad female faces in patients, who misperceived neutral faces as sad. The results point to memory and executive deficits in addition to a "negative" bias in emotion recognition in OCD patients.  相似文献   
998.
Prefrontal repetitive transcranial magnetic stimulation (rTMS) has been shown to increase striatal dopaminergic activity. Here we investigated dopaminergic neurotransmission using single photon emission computed tomography (SPECT) and [(123)I]IBZM to indirectly assess the change in endogenous striatal dopamine concentration upon rTMS as compared with d-amphetamine challenge. SPECT imaging was performed twice each in five patients during rTMS, and in two patients who received 0.3 mg/kg D-amphetamine. Administration of rTMS led to a mean relative decrease in striatal IBZM binding by 9.6+/-6.2%, and d-amphetamine challenge (n=4) induced a mean relative reduction by 8+/-2.95% (difference not statistically significant). Acute rTMS challenge showed similar striatal dopaminergic effects to those associated with the administration of d-amphetamine, a substance known to increase synaptic dopamine.  相似文献   
999.
This article deals with methods and instruments used to identify high risk parents and early developing risks of infants and young children during the pre- and postnatal period in order to develop early intervention strategies based on early diagnosis in the context of parent-child-relationship. The specific experiences of our research approaches, funded by the German ministry of education and research (BMBF) from 2003 to 2007 at the University of Applied Sciences in Potsdam in cooperation with the parent counselling centre "Vom S?ugling zum Kleinkind" are reflected. An interaction and communication focused strategy was developed to help to identify early development risks and resources in the parent-infant-relationship at the age of 0-3 years. After testing the diagnostical approach of this social-emotional development screening (SEE-0-3) in a current evaluation study on a high-risk-population, it was integrated as one module of early diagnosis into the early intervention program "STEEP--Steps toward effective and enjoyable parenting" which is based on the attachment theory. Using a concrete case it will first be discussed which kind of approaches to becoming parents with high risk factors can be developed on the basis of attachment reflecting acting and second which possibilities an interaction and video based concept could offer in the field of early diagnosis and intervention with families of infants and young children.  相似文献   
1000.
PHACE is an acronym to describe the association of posterior fossa brain malformations, hemangiomas, arterial anomalies, coarctation of the aorta, cardiac defects, and eye abnormalities. More than 200 cases have been reported. The present report presents the cases of two female infants with PHACE syndrome, both of whom had additional congenital defects of subependymal gray matter heterotopia, craniofacial arterial anomalies, and pituitary dysfunction. One had an extensive segmental facial hemangioma with ipsilateral intracranial hemangiomas. The other had multiple cutaneous hemangiomas, but no segmental facial hemangioma. These two cases suggest a further expansion of the spectrum of PHACE to include other forms of disordered cerebral development and endocrine dysfunction.  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