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   39636篇
  免费   2183篇
  国内免费   122篇
耳鼻咽喉   457篇
儿科学   2270篇
妇产科学   787篇
基础医学   5209篇
口腔科学   840篇
临床医学   2773篇
内科学   7941篇
皮肤病学   892篇
神经病学   2181篇
特种医学   869篇
外科学   5308篇
综合类   1430篇
一般理论   19篇
预防医学   2413篇
眼科学   1741篇
药学   3919篇
中国医学   337篇
肿瘤学   2555篇
  2023年   259篇
  2022年   725篇
  2021年   1239篇
  2020年   700篇
  2019年   932篇
  2018年   1148篇
  2017年   796篇
  2016年   1033篇
  2015年   1087篇
  2014年   1470篇
  2013年   1955篇
  2012年   2680篇
  2011年   2712篇
  2010年   1531篇
  2009年   1352篇
  2008年   1979篇
  2007年   1925篇
  2006年   1970篇
  2005年   1556篇
  2004年   1535篇
  2003年   1298篇
  2002年   1133篇
  2001年   910篇
  2000年   959篇
  1999年   785篇
  1998年   347篇
  1997年   238篇
  1996年   236篇
  1995年   232篇
  1994年   192篇
  1993年   163篇
  1992年   546篇
  1991年   451篇
  1990年   470篇
  1989年   450篇
  1988年   392篇
  1987年   387篇
  1986年   374篇
  1985年   358篇
  1984年   286篇
  1983年   245篇
  1982年   152篇
  1979年   260篇
  1978年   165篇
  1977年   200篇
  1975年   181篇
  1974年   198篇
  1973年   195篇
  1972年   188篇
  1971年   173篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
We have obtained multislice magnetic resonance (MR) images of the eye and calculated ocular dimensions along the three cardinal axes: antero-posterior (A-P), equatorial, and vertical. We found no difference in the shape of hyperopic (average refractive error: +3.72 D) and emmetropic eyes, both of which had an equatorial diameter longer than the A-P and vertical diameters. Myopic eyes (average refractive error: -6.54 D) were larger than hyperopic eyes, and most had the same spheroelliptical shape as that of the emmetropic and hyperopic eyes. The results suggest that during myopic progression an overall enlargement or a radial volume expansion has occurred.  相似文献   
73.
During the period 1982-86, a total of 657 Salmonella strains were isolated from various clinical samples processed in the Microbiology laboratory of Goa Medical College, Bambolim, Goa. The strains were distributed amongst 23 different Salmonella serotypes. The commonest serotypes encountered were S.typhimurium (66%) and S.typhi (24%), the other serotypes were S.bareilly (5.4%), S.paratyphi B (1.2%), S.newport (1.2%) and S.chester (0.8%). Stool samples yielded the maximum Salmonella isolates of which the S.typhimurium was the highest followed by S.bareilly.  相似文献   
74.
A 35 years old lady presented with fever, biliary colic, mild jaundice, indigestion and flatulence. The upper abdominal ultrasonography revealed cholecystitis with sludge and a round worm in the common bile duct. Laparoscopic cholecystectomy and exploration of the bile duct for the removal of round worm was performed. The post-operative period was uneventful and the patient was discharged fit on the 4th post-operative day.  相似文献   
75.
76.
Food systems are complex and inhomogeneous in nature. Ultrasonic propagation velocity in the food systems, in this case processed milk cream and vegetable oils, is studied. Ultrasonic properties of the food systems are similar to those of complex biological tissues. The presence of vegetable oil as an adulterant in the processed milk cream is detected with the help of a double-probe-through-transmission ultrasonic technique. The present study helps to maintain quality control of various food systems, particularly with regard to their adulteration, if any.  相似文献   
77.
Abstract: The effects of 1,2,3,4-tetrahydro-9-aminoacridine (THA) on uptake rates of radioactive 5-hydroxytryptamine (5-HT) and dopamine were investigated in rat diencephalon and striatal homogenates, respectively. Six and eight μM of THA were needed to inhibit 50% of dopamine and 5-HT uptake rates. Kinetic parameters, Km and Vmax, using six different concentrations of dopamine and 5-HT were estimated in the presence or absence of THA. A significant decrease in Vmax without any change in Km values was observed for both dopamine and 5-HT in the presence of THA. The results show that THA is a non-competitive uptake inhibitor of dopamine and 5-HT in the nerve terminals. The re-uptake blocking effect of THA on dopaminergic and serotonergic neurones, following THA treatment, might lead to increased levels of these monoamines in brains of Alzheimer patients and contribute in the therapeutic effects of the drug.  相似文献   
78.
AIMS: To estimate the prevalence and distribution of the metabolic syndrome (MS) in adolescents attending school in the north Indian city of Chandigarh. RESEARCH DESIGN AND METHODS: At total of 1083 adolescents attending school (aged 12-17 years) participated in a community-based cross-sectional survey. Anthropometric examination included height, weight, body mass index, waist circumference, hip circumference, waist-hip ratio and blood pressure measurement. A fasting blood sample was taken for measurement of glucose, insulin and lipid profile. Socio-demographic characteristics were investigated using a questionnaire. The metabolic syndrome was determined by the National Cholesterol Education Program Adult Treatment Panel III definition modified for age. RESULTS: The overall prevalence of MS in adolescents was 4.2%. However, the prevalence rose to 5.8% when the fasting plasma glucose cut-off was lowered to 5.5 mmol/l. There was no gender difference in the distribution of MS. When stratified by body mass index (BMI), 5.5% adolescents were overweight (BMI > or = 95th percentile), while 4% were at risk for overweight (BMI between 85th and 95th percentile). Of the overweight adolescents, 36.6% met the criteria for MS, while 11.5% at risk for overweight and only 1.9% of the normal population had MS (P < 0.0001). Low high-density lipoprotein was the most common and abdominal obesity the least common constituent of MS. There was a significant difference (P < 0.0001) between the prevalence of MS adolescents from low to high socio-economic strata. CONCLUSIONS: A substantial number (4.2%) of north Indian adolescents and 36.6% of overweight adolescents had MS. This poses a serious threat to the current and future health of these young people.  相似文献   
79.
Two children out of three siblings of a family presented with tiredness, fatigue, and breathlessness for more than 6 months. Examination of peripheral blood smear, bone marrow aspirate, and a positive acidified serum test (HEMPAS) revealed these children to be a case of congenital dyserythropoietic anemia type II. This case is reported because of its rarity.  相似文献   
80.
Mirror movements (MM) occur in early, asymmetric Parkinson's disease (PD). To examine the pathophysiology of MM in PD, we studied 13 PD patients with MM (PD-MM), 7 PD patients without MM (PD-NM), and 14 normal subjects. Cross-correlogram did not detect common synaptic input to motoneuron pools innervating homologous hand muscles in PD-MM patients. Transcranial magnetic stimulation studies showed no significant difference in ipsilateral motor-evoked potentials between PD-MM patients and normal subjects. The MM side of PD-MM patients showed a slower increase in ipsilateral silent period area with higher level of muscle contraction than the non-MM side and normal subjects. There was less interhemispheric inhibition (IHI) at long interstimulus intervals of 20 to 50 ms in PD-MM than PD-NM. IHI reduced short interval intracortical inhibition in normal subjects and PD-NM, but not in PD-MM. IHI significantly increased intracortical facilitation in PD-MM and PD-NM patients, but not in normal subjects. Our results suggest that MM in PD is due to activation of the contralateral motor cortex. PD-MM patients had reduced transcallosal inhibitory effects on cortical output neurons and on intracortical inhibitory circuits compared to PD-NM patients and controls. These deficits in transcallosal inhibition may contribute to MM in PD patients.  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