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   243774篇
  免费   12087篇
  国内免费   409篇
耳鼻咽喉   3221篇
儿科学   7670篇
妇产科学   5105篇
基础医学   34856篇
口腔科学   5559篇
临床医学   19130篇
内科学   54341篇
皮肤病学   6670篇
神经病学   21610篇
特种医学   7223篇
外国民族医学   101篇
外科学   30574篇
综合类   1038篇
一般理论   62篇
预防医学   22335篇
眼科学   4714篇
药学   16983篇
中国医学   752篇
肿瘤学   14326篇
  2023年   1277篇
  2022年   1054篇
  2021年   3889篇
  2020年   2264篇
  2019年   4289篇
  2018年   7735篇
  2017年   5033篇
  2016年   5046篇
  2015年   5599篇
  2014年   6085篇
  2013年   9679篇
  2012年   16547篇
  2011年   16575篇
  2010年   8349篇
  2009年   6345篇
  2008年   14248篇
  2007年   15206篇
  2006年   14010篇
  2005年   13880篇
  2004年   13025篇
  2003年   11916篇
  2002年   11299篇
  2001年   6506篇
  2000年   6683篇
  1999年   5924篇
  1998年   1000篇
  1997年   836篇
  1996年   774篇
  1995年   707篇
  1992年   3331篇
  1991年   2952篇
  1990年   2845篇
  1989年   2562篇
  1988年   2422篇
  1987年   2273篇
  1986年   2142篇
  1985年   1927篇
  1984年   1435篇
  1983年   1209篇
  1979年   1224篇
  1978年   854篇
  1977年   807篇
  1975年   812篇
  1974年   1005篇
  1973年   1017篇
  1972年   961篇
  1971年   945篇
  1970年   874篇
  1969年   931篇
  1968年   801篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
79 patients with ischaemic stroke were investigated, with 31 patients showing a pure hemiparesis, 22 an additional depressive syndrome and 26 a dementia. After an average time intervall of 28 months, a follow-up investigation was performed on these 3 groups relative to their course and rehabilitation outcome. No significant differences were present between the 3 groups as regards age and sex distribution as well as hemisyndrome severity. The neurological and psychiatric findings at follow-up differed significantly from the primary findings. Also, significant differences were found in the degree of disability, and in the self- and family ratings of rehabilitation outcome, with a poorer long-term course, i.e. a higher degree of disability, significantly more frequent in the dementia group. Comparison of self- and family-ratings showed that self-ratings given were significantly worse in the dementia and depressive groups, whereas patients with purely neurological symptoms rated themselves better than their relatives did.  相似文献   
992.
In order to investigate the possibility of using [1-11C] labelled 3,4-dihydroxyphenylalanine (DOPA) and tyrosine as radiopharmaceuticals for the detection of eye melanoma, the biodistributions of the same 1- and 3-14C-labelled compounds were investigated in Syrian golden hamsters with Greene melanoma. The results of these investigations were compared with positron emission tomography (PET) images of 11C labelled DOPA and tyrosine. The synthesis of these 11C labelled compounds procures of DL mixture, from which D and L forms can be separated. One h after intravenous injection, both 14C labelled DL-, L- and D-DOPA showed a high uptake in tumour tissue, that of DL- and D-DOPA being the highest. These high uptakes, together with relatively low uptake in bone, skin and eye resulted in high tumour/non tumour ratio (for DL-DOPA 5.9, 4.5 and 6.6 respectively). Extraction of the tumour tissue with trichloroacetic acid showed that L-DOPA was mainly incorporated into melanin, whereas D-DOPA was not. Also, the uptake 1 h after intravenous injection of 1-14C-L- and DL-tyrosine into the tumour were high, but L- and DL- were less different; tumour/non tumour ratios were favorable. PET images of the tumour obtained 40-80 min after injection of the [1-11C] labelled DOPA and tyrosine confirmed that melanoma detection was promising and that D-DOPA produced a better melanoma image than L-DOPA.  相似文献   
993.
994.
995.
Thirty six patients were studied with a classical photoparoxysmal EEG response to intermittent photic stimulation (IPS). Clinical observations and complaints reported by patients during standardised IPS were recorded and compared with historical data. Twenty seven patients experienced impaired consciousness or showed motor phenomena such as involuntary opening of the eyes or jerking on one or both sides of the body. Twenty five patients had sensations such as pain in the eyes, jerking etc. There existed no relation between the duration of the evoked discharges (0.5-3 seconds) and observed signs or complaints. In 11 instances the clinical features found during IPS were not reported in a history taken from the patient and relatives.  相似文献   
996.
997.
998.
Malignant rhabdoid tumors are highly aggressive childhood tumors. Recently, all of the malignant rhabdoid tumors, whatever their location, have been related to the inactivation of the hSNF5/INI1 gene. A subset of cerebral tumors, associated with malignant rhabdoid tumors or isolated ones arising in siblings, showed similar molecular alterations. We report for the first time in monozygotic twins a congenital disseminated malignant rhabdoid tumor in one twin and a cerebellar tumor mimicking a medulloblastoma in the other. Molecular analysis revealed similar alterations for both tumors: a deletion of exon 7 of the hSNF5/INI1 gene in one allele, and a point mutation in the same exon in the other, suggesting a common genetic pathway. Analysis of constitutional DNA revealed a germline mutation. These findings are in favor of a common etiology for rhabdoid tumor and a subset of brain tumors developing in infancy.  相似文献   
999.
We assessed the prevalence of Parkinson's disease in Cantalejo, Spain. In 1994, we screened 1,579 persons (age > or = 40 years) using a high-sensitivity method. Cases fulfilling established clinical criteria were followed for a minimum of 3 years. Prevalences were compared with those from other door-to-door surveys. We detected 27 individuals with parkinsonism, 20 of whom had Parkinson's disease. The prevalence of Parkinson's disease increased with age and, when age-adjusted to European standards, was 9.01 per 1,000 (age 40 years and over; 10.78 in men and 5.23 in women). Of the 11 men, three were in Hoehn & Yahr grades III-IV, but six of the nine women were more severely affected. Overall, we found 18 newly diagnosed cases of parkinsonism, 13 of which were Parkinson's disease, and the majority of which were in men aged 80 years or older with a mean duration of illness of 5 years. Our prevalence figures are the highest reported, apparently because of the inclusion of several very elderly men. Parkinson's disease in Cantalejo is less severe in men than in women, particularly in those newly diagnosed. Despite the low numbers, the high prevalence and sex-related pattern are unexplained but they probably relate to the high sensitivity of the screening method.  相似文献   
1000.
The pharmacokinetics of a single oral dose of the neuroleptic drug zuclopenthixol (10 or 6 mg) was studied in 6 extensive and 6 poor metabolizers of debrisoquine. The peak plasma concentrations of zuclopenthixol did not differ between the phenotypes, whereas the plasma elimination half-life was significantly longer in poor than in extensive metabolizers (29.9 +/- 6.6 vs 17.6 +/- 6.9 h). Accordingly, the total oral plasma clearance was lower in poor than in extensive metabolizers (0.78 +/- 0.27 vs 2.12 +/- 0.65 1/h/kg). Ten of the volunteers had previously participated in a similar study in which the kinetics of perphenazine, another neuroleptic drug, were studied in poor and in extensive metabolizers of debrisoquine. There was a significant correlation between the oral clearance of perphenazine and that of zuclopenthixol among these 10 subjects. The study indicates that the disposition of zuclopenthixol, as well as that of perphenazine, is related to the genetically determined capacity to hydroxylate debrisoquine. The significance of this polymorphism for the clinical use of neuroleptics is discussed.  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