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   3361868篇
  免费   241847篇
  国内免费   8555篇
耳鼻咽喉   46445篇
儿科学   112331篇
妇产科学   93098篇
基础医学   472493篇
口腔科学   92448篇
临床医学   304949篇
内科学   660544篇
皮肤病学   78480篇
神经病学   273040篇
特种医学   130243篇
外国民族医学   1282篇
外科学   505542篇
综合类   69789篇
现状与发展   6篇
一般理论   1221篇
预防医学   257639篇
眼科学   75874篇
药学   247523篇
  9篇
中国医学   6787篇
肿瘤学   182527篇
  2019年   25879篇
  2018年   36594篇
  2017年   28018篇
  2016年   32188篇
  2015年   36276篇
  2014年   50027篇
  2013年   75568篇
  2012年   101073篇
  2011年   107128篇
  2010年   64631篇
  2009年   61795篇
  2008年   100562篇
  2007年   107060篇
  2006年   108595篇
  2005年   104527篇
  2004年   101133篇
  2003年   97698篇
  2002年   94598篇
  2001年   161240篇
  2000年   165694篇
  1999年   140208篇
  1998年   40211篇
  1997年   35787篇
  1996年   35984篇
  1995年   34704篇
  1994年   32158篇
  1993年   30138篇
  1992年   110098篇
  1991年   106358篇
  1990年   103304篇
  1989年   99747篇
  1988年   91545篇
  1987年   89835篇
  1986年   84056篇
  1985年   80323篇
  1984年   60050篇
  1983年   50851篇
  1982年   29913篇
  1981年   26995篇
  1979年   53343篇
  1978年   37497篇
  1977年   31976篇
  1976年   29656篇
  1975年   31696篇
  1974年   37326篇
  1973年   35577篇
  1972年   33272篇
  1971年   30668篇
  1970年   28575篇
  1969年   26930篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The sudden appearance of multiple keratoacanthomas in a patient who has sustained a thermal burn is extremely uncommon. This case report describes a sixty-four-year-old man who noted multiple keratoacanthomas within three weeks after being involved in a gasoline explosion. Multiple keratoacanthomas appear to be a rare complication of thermal cutaneous injury in predisposed persons.  相似文献   
992.
993.
We examined binding to excitatory amino acid and inhibitory amino acid receptors in frozen hippocampal sections prepared from surgical specimens resected from 8 individuals with medically refractory temporal lobe epilepsy. The excitatory receptors studied included N-methyl-D-aspartate (NMDA), strychnine-insensitive glycine, phencyclidine, and quisqualate. The inhibitory receptors studied were gamma-aminobutyric acid type A (GABAA) and benzodiazepine. Excitatory and inhibitory amino acid receptor binding were differentially altered in the patients with temporal lobe epilepsy in comparison to 8 age-comparable autopsy control subjects, and changes in receptor binding were regionally selective in four areas. Binding to phencyclidine receptors associated with the NMDA channel was reduced by 35 to 70% in all regions in the hippocampi of the patients. In contrast, binding to the NMDA recognition site and its associated glycine modulatory site was elevated by 20 to 110% in the cornu ammonis (CA) 1 area and dentate gyrus of the hippocampus of the patients. Binding to these sites was unaffected in area CA4. Binding to the quisqualate-type excitatory amino acid receptor was unchanged in all regions except the stratum lacunosum moleculare CA1, where it was increased by 63%. GABAA and benzodiazepine receptor binding was reduced by 20 to 60% in CA1 and CA4, but unchanged in dentate gyrus. The data indicate that excitatory and inhibitory amino acid receptors are altered in the hippocampus of patients with temporal lobe epilepsy.  相似文献   
994.
Artificial dopamine agonists are widely employed for the treatment of idiopathic parkinsonism. Pleuropulmonary disease has previously been reported to occur with the use of bromocriptine and mesulergine. We report similar adverse effects induced by the newer agonists lisuride and cabergoline. All these agents are tetracyclic ergot derivatives. This suggests a causal link between ergot-derived dopamine agonists and pleuropulmonary disease.  相似文献   
995.
Reports on individual nonbehavioral child and adolescent psychotherapy since 1963 are reviewed. Inclusion criteria required some minimal contrasting group. Forty-three studies were assessed for basic methodological adequacy and main findings. The authors conclude that summary impressions from this body of literature cannot be made due to the magnitude of the flaws in basic psychotherapy research methodology. Suggestions are made regarding the future of child and adolescent psychotherapy research.  相似文献   
996.
In acute experiments on cats the activity of the motor cortex neurons was recorded. The dynamics of interneuronal connections at passive bending and electrostimulation of the limb contralateral to the place of recording was studied by methods of cross-correlation analysis of impulse trains. At passive bending a considerable decrease of the number of common inputs between neighbouring neurons (within 50-100 microns) and an increase in their number between remote (from 100 till 400 microns) cortical neurons. During electro-stimulation a certain increase in the number of direct inhibitory interactions between the neighbouring neurons was observed.  相似文献   
997.
Computer tomography (CT) of the brain is of value for finding potentially correctable lesions in adult patients with new onset seizures. The value of CT is unknown, however, for finding such lesions in adult chronic epileptic patients without prior CT. We compared a group of 177 adult patients who had CT within a year from the onset of seizures to a group of 93 patients who had a history of seizures for more than a year before CT was performed. In the first group, 33 potentially correctable lesions (19%) were found including 17 tumors. The group with chronic epilepsy had 4 (4%) potentially correctable lesions: 3 arteriovenous malformations and 1 meningioma. It seems that CT is of value in discovering potentially removable lesions in chronic epileptic patients, but the likelihood is relatively small. The incidence of stable structural lesions seems to be similar in the two groups.  相似文献   
998.
Four cases of cervical vertebral artery (VA) dissection are reported. In three patients VA dissection was associated with neck trauma. All patients were young or middle-aged (range 27 to 49 years). In two there was a history of migraine. Pain preceded neurological symptoms from hours to six weeks. Three patients had neurological deficits including elements of the lateral medullary syndrome, and one experienced recurrent transient ischaemic attacks in the vertebrobasilar territory. Angiographic findings included irregular stenosis, occlusion and pseudoaneurysm; in two patients VA abnormalities were bilateral. All patients were treated with anticoagulants and improved. In a review of 28 cases with traumatic dissection and 29 cases with spontaneous dissection of the VA reported in the literature, distinct clinical and angiographic features emerge. Aetiology remains obscure in most cases of spontaneous dissection and management is still controversial.  相似文献   
999.
This study was performed to gain a better understanding of EEG frequency analysis test-retest reliability in normal healthy adults, and to evaluate factors which could influence the measured inter-record differences. Nineteen subjects underwent serial EEG recordings at 5 min and 12-16 week intervals. Records were visually edited using a standardized protocol, and FFT frequency analysis performed on segments of 60, 40, or 20 sec total length. Correlation coefficients for broad band features averaged 0.92 over the 5 min retest interval and 0.84 over the 12-16 week interval. There was essentially no difference between correlation coefficients of absolute and relative power features. Coefficients based on 60 sec records were marginally higher than those of 40 or 20 sec records. On the other hand, test-retest percent differences were typically lower for relative as opposed to absolute power features, and 60 sec records showed consistently lower percent differences than did 40 or particularly 20 sec records. Peak alpha frequency and mean frequency were the most stable EEG features at either interval. Montage had significant effects on test-retest differences at the 12-16 week interval. A significant association between intra-record and inter-record variability could not be demonstrated.  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