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   1423篇
  免费   87篇
  国内免费   15篇
耳鼻咽喉   14篇
儿科学   73篇
妇产科学   14篇
基础医学   200篇
口腔科学   101篇
临床医学   128篇
内科学   355篇
皮肤病学   46篇
神经病学   74篇
特种医学   138篇
外科学   113篇
综合类   37篇
一般理论   1篇
预防医学   118篇
眼科学   9篇
药学   58篇
中国医学   6篇
肿瘤学   40篇
  2023年   15篇
  2022年   20篇
  2021年   38篇
  2020年   31篇
  2019年   45篇
  2018年   46篇
  2017年   34篇
  2016年   33篇
  2015年   46篇
  2014年   55篇
  2013年   48篇
  2012年   85篇
  2011年   68篇
  2010年   77篇
  2009年   57篇
  2008年   57篇
  2007年   65篇
  2006年   52篇
  2005年   42篇
  2004年   31篇
  2003年   29篇
  2002年   24篇
  2001年   15篇
  2000年   18篇
  1999年   25篇
  1998年   53篇
  1997年   46篇
  1996年   38篇
  1995年   28篇
  1994年   38篇
  1993年   30篇
  1992年   8篇
  1991年   10篇
  1990年   9篇
  1989年   25篇
  1988年   18篇
  1987年   15篇
  1986年   13篇
  1985年   8篇
  1984年   7篇
  1983年   11篇
  1982年   16篇
  1981年   11篇
  1980年   14篇
  1979年   5篇
  1977年   14篇
  1976年   7篇
  1975年   7篇
  1970年   4篇
  1965年   4篇
排序方式: 共有1525条查询结果,搜索用时 31 毫秒
101.
Convergent findings from neuropsychological and neuroimaging studies have suggested that neural dysfunction in frontal-subcortical circuits may play a central role in the pathophysiology of obsessive-compulsive disorder (OCD). To further examine the relationship between these two sets of findings we investigated both neuropsychological functions and regional cerebral blood flow (rCBF) in a combined study. Fourteen unmedicated patients fulfilling DSM-IV criteria for OCD and 14 healthy controls matched for age, gender, handedness, and education were assessed on neuropsychological tests that included Trail Making Test (TMT), Rey Complex Figure Test (RCF) (copy and 5-min recall), Verbal Fluency Test (VFT), and Wisconsin Card Sorting Test (WCST). rCBF was studied with 99 mTc-hexamethyl-propyleneamine-oxime (HMPAO) single photon emission computed tomography (SPECT). Patients performed more poorly than controls (P<.05) on RCF (copy), VFT, and WCST (perseverative errors). Spearman's correlations indicated that severity of OCD correlated inversely with performance on the RCF (copy and recall scores) and positively with rCBF in the right thalamus. Positive correlations were observed between nonperseverative errors (WCST) and rCBF in frontal areas and anterior cingulate. Perseverative errors (WCST) correlated negatively with rCBF in the right thalamus. These findings are consistent with most previously published studies and suggest neural dysfunctions in the frontal-subcortical circuits probably more pronounced in the right hemisphere. They also extend the existing research, showing associations between deficits in cortical-subcortical circuitry and performance on neuropsychological tests of controlled attention and visuospatial functions.  相似文献   
102.
103.
This study evaluated the accuracy of the interpretation of the chest film in delineating localised abnormalities of ventilation and perfusion, as well as the overall severity of airways obstruction, exercise tolerance, and clinical condition in children with cystic fibrosis. Radiographic findings in various regions of the chest film were compared with the functional values obtained with regional lung function tests which evaluated the arrival and disappearance of boluses of radioactive nitrogen given by inhalation and infusion. While the more severely affected areas on the chest radiograph were found to correlate with similar regions on the lung function tests, as did overall scores, errors occurred in some cases if the x-ray film alone was used as a judge of regional physiological derangement. In addition the degree of airways obstruction, the exercise tolerance on a cycle ergometer, and clinical grading, each correlated significantly with the radiographic score. We conclude that the chest radiograph is a good indicator of the overall severity of the lung disease and that it correlates well with exercise tolerance and clinical condition in cystic fibrosis.  相似文献   
104.
Scintiscans of liver and spleen using technetium 99m sulphur colloid in 15 infants with extrahepatic biliary atresia and 11 infants with severe obstructive jaundice (7 with genetic deficiency of alpha 1-antitrypsin) showed similar hepatic size, pattern of isotope uptake, and splenic abnormality with no distinguishing features. In 37 older children with a variety of liver disorders, the scan was invaluable in showing filling defects in five instances. Selenomethionine was taken up not only by the two filling defects due to hepatoblastoma but also in a haemangioendothelioma. In the remaining patiens liver scanning confirmed hepatic abnormality and the necessity for more specific invasive diagnostic investigations.  相似文献   
105.
High-frequency oscillation (HFO) is a technique frequently used in neonatal resuscitation, but which has yet to be evaluated. The use of intrathoracic pressures may have an effect on the cerebral circulation of immature neonates. The aim of this study was to examine the variations in cerebral blood velocity and oxygenation during brief pulmonary inflations (sighs), by focusing on alveolar recruitment. In this prospective study performed in 13 intubated and ventilated neonates (alpha = 5%; 1-beta = 80%), mean blood velocity and Doppler Resistance Index were measured, and variations in chromophores concentrations were evaluated by near infrared spectroscopy. Brief inflations at 4 cm H2O above the mean regulated intra-thoracic pressure did not cause any variation in the parameters measured. An explanation for this discordance with animal studies may be the level of pressure chosen, which could be more appropriate for the pulmonary compliance of neonates.  相似文献   
106.
Al‐Shibli K, Al‐Saad S, Andersen S, Donnem T, Bremnes RM, Busund L‐T. The prognostic value of intraepithelial and stromal CD3‐, CD117‐ and CD138‐positive cells in non‐small cell lung carcinoma. APMIS 2010; 118: 371–82. The major value of prognostic markers in potentially curable non‐small cell lung carcinoma (NSCLC) should be to guide therapy after surgical treatment. Although tumor‐infiltrating T lymphocytes and plasma cells have been documented in NSCLC, a clear association with clinical outcome, especially for the stromal component, has not been well established. The aim of this study was to elucidate the prognostic significance of these cells/markers in the epithelial and stromal compartments of NSCLC. Tissue microarrays from 335 resected, stage I‐IIIA, NSCLC were constructed by duplicate cores from viable neoplastic epithelial and stromal areas. Immunohistochemistry was used to evaluate the infiltration of CD3+, CD117+ as well as CD138+ cells in epithelial and stromal areas. In univariate analyses, increasing numbers of stromal CD3+ (p = 0.001) and epithelial CD3+ cells (p = 0.004) correlated significantly with an improved disease‐specific survival. No such relation was noted with CD3+ or CD117+ cells. In the multivariate analysis, stromal CD3+ cells was an independent prognostic factor for disease‐specific survival (HR 1.925, CI 1.21–3.04, p = 0.005). Increased presence of the pan T‐cell marker, CD3, which is an independent factor, correlates with improved clinical outcome in NSCLC. This prognostic impact of T cells is clearer in the tumor stroma. Neither plasma cells nor mast cells were prognostic indicators in our cohort.  相似文献   
107.
Speech discrimination and phonological working memory in children with ADHD   总被引:1,自引:0,他引:1  
This study examined phonological working memory and speech discrimination among children with attention-deficit-hyperactivity disorder (ADHD) with and without motor problems. Forty-one children were assigned to three groups; children with ADHD (N=9), children with ADHD plus developmental coordination disorder (ADHD+, N=13), and age-matched control children (N=19). The subjects' ability to classify stimulus pairs was examined in two experiments. The first experiment required subjects to discriminate pairs of monosyllabic stimuli with contrasting consonants to test speech discrimination without using a working-memory load. In the second protocol, subjects were exposed to two- to five-syllabic non-word pairs with contrasting vowels in order to test speech discrimination with a working-memory load. The subjects classified the pairs as being either the same or different in both experiments. No significant differences were found between the subject groups in the discrimination task with monosyllables. When exposed to the two- to five-syllabic stimuli, the ADHD+ group scored significantly lower than both other groups. This was attributed to a higher sensitivity to working-memory load. Some possible explanations of this effect are discussed.  相似文献   
108.
Original Gianturco expandable stents and their modifications were used to create an experimental intrahepatic portacaval anastomosis (EIPCA) in 30 young domestic swine without portal hypertension. The study focused on the design of a suitable stent, the technique of its application, and the evaluation of short-term patency of the EIPCA. A stent with a 2.5-cm-long body and wire skirts on both ends was most suitable for EIPCA creation. Well-positioned stents shunted most of the portal blood in the inferior vena cava circulation and remained patent for 4-6 weeks. Ingrowth of liver parenchyma and abundant proliferation of the intima and connective tissue inside the stent lumen in these rapidly growing animals gradually decreased EIPCA patency, and thrombus formation with diminished blood flow closed them completely.  相似文献   
109.
110.
Transient synovitis of the hip in children: role of US   总被引:7,自引:0,他引:7  
Transient synovitis of the hip remains a common diagnostic problem for the clinician. The physical signs are not pathognomonic of the condition, and the classic technical examinations are of little help. Therefore, the authors retrospectively studied the value of hip arthrosonography in 46 children with clinical symptoms suggesting pathologic hip conditions. In 20 of the 21 patients with a final diagnosis of transient synovitis, articular effusion was detected on ultrasound (US). Conventional radiography showed an increased medial joint space in only eight of these patients. Increased echogenicity of the articular fluid was found in both transient synovitis and septic arthritis. The high sensitivity of US in detecting intraarticular fluid was demonstrated by cadaver studies.  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