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   1477篇
  免费   86篇
  国内免费   7篇
耳鼻咽喉   25篇
儿科学   28篇
妇产科学   13篇
基础医学   159篇
口腔科学   83篇
临床医学   138篇
内科学   295篇
皮肤病学   9篇
神经病学   133篇
特种医学   34篇
外国民族医学   1篇
外科学   337篇
综合类   7篇
一般理论   1篇
预防医学   86篇
眼科学   50篇
药学   65篇
中国医学   1篇
肿瘤学   105篇
  2023年   10篇
  2022年   19篇
  2021年   19篇
  2020年   24篇
  2019年   26篇
  2018年   30篇
  2017年   22篇
  2016年   27篇
  2015年   44篇
  2014年   47篇
  2013年   66篇
  2012年   97篇
  2011年   83篇
  2010年   67篇
  2009年   54篇
  2008年   91篇
  2007年   105篇
  2006年   81篇
  2005年   71篇
  2004年   77篇
  2003年   71篇
  2002年   82篇
  2001年   35篇
  2000年   48篇
  1999年   23篇
  1998年   20篇
  1997年   16篇
  1996年   14篇
  1995年   14篇
  1994年   13篇
  1993年   14篇
  1992年   7篇
  1991年   14篇
  1990年   14篇
  1989年   17篇
  1988年   8篇
  1987年   11篇
  1986年   6篇
  1984年   7篇
  1982年   5篇
  1981年   6篇
  1979年   8篇
  1978年   10篇
  1977年   7篇
  1976年   6篇
  1973年   3篇
  1972年   2篇
  1971年   8篇
  1970年   4篇
  1965年   3篇
排序方式: 共有1570条查询结果,搜索用时 46 毫秒
1.
We examined 334 legs in 167 consecutive patients with advanced peripheral ischemic disease using color Doppler sonography and angiography. Angiography revealed 714 lesions (369 nonsignificant stenoses, 297 significant stenoses, and 48 occlusions) in the 334 legs examined. Overall, color Doppler sonography revealed diagnostic agreement with angiography in 668 of 714 lesions (93.5%), including 343 of 369 (92.9%) nonsignificant stenoses, 279 of 297 (93.9%) significant stenoses, and 46 of 48 (95.8%) occlusions. Overestimation occurred in 26 of 369 (7%) nonsignificant stenoses and 3 of 297 (1%) significant stenoses. Underestimation was observed in 15 of 297 (5%) significant stenoses and in 2 of 48 (4.2%) occlusions. Peak systolic velocity ratio correlated better (P < 0.01) than peak systolic velocity with diameter reduction percentage as assessed at angiography. Color Doppler sonography is an accurate noninvasive method for evaluating patients with peripheral ischemic disease.  相似文献   
2.
BACKGROUND: To obtain the best surgical results in orthognathic surgery, treatment planning and the evaluation of results should be performed on measurable three-dimensional reproductions of the face of the patients, and compared to reference subjects. METHODS: Seven women aged 18-35 years, all with a skeletal Class III and mandibular asymmetry, were assessed both before (on average, 2 months) and after (on average, 10.7 months) surgical intervention (mandibular reduction by sagittal split osteotomy and LeFort I maxillary advancement). The three-dimensional coordinates of 50 soft tissue facial landmarks (face, eyes, nose, mouth and lips, ears) were collected with a noninvasive, electromagnetic digitizer; facial volumes were estimated, and compared to reference values collected in 87 healthy women of the same age and ethnic group. Inter-individual modifications in facial shape were also assessed. RESULTS: Before surgery the patients had smaller faces than the reference women, with larger lower lips and noses. A large within-group variability was found. Surgical treatment significantly reduced total facial volume and mandibular volume, increased total and upper lip volumes (Student's t test, p<0.05), and made all values more homogenous within the group. Shape differences were significantly larger before than after surgery. On average, right side gonion was the landmark that moved the most, closely followed by menton, while the tragi and ala nasi moved the least. The three-dimensional approach used in this study enabled quantitative evaluation of the final soft tissue results of surgery, without submitting the patients to invasive procedures.  相似文献   
3.
The results of the first 3 year' collaboration of the Italian Registry of Paediatric Chronic Peritoneal Dialysis (CPD) (1986–1988) are presented. This Registry acquired data on the majority of the paediatric patients treated with CPD in Italy, thus providing a national picture in a field where few nationwide surveys are available. Patients of less than 15 years of age at the start of dialysis were enrolled and clinical data collected until the age of 19 years. The number of nephrological paediatric centres participating in the Registry increased from 7 in 1986 to 11 in 1988. The total number of patients on CPD was 70 and the percentage of dialysed children treated with CPD ranged from 40.2% to 43.6%. Data on 89 peritoneal catheters were collected: during 1417 dialysis-months 70 catheter-related complications were observed (1:20.8 dialysis-months); actuarial catheter survival was 92.7% at 6 months, 84.8% at 1 year and 68.8% at 2 years. The incidence of peritonitis changed from 1 episode every 10.9 patient-months in 1986 to 1 every 19.8 in 1988. Abdominal hernias were the other main clinical complication observed. The survival of patients was 92.5% at 3 years, while the technique survival at the same time was 84%.  相似文献   
4.
Little has been done to investigate the biochemical basis of chronic daily headache (CDH). Our group has recently demonstrated an increase in the cerebrospinal fluid (CSF) levels of nerve growth factor (NGF) in CDH patients, supporting the involvement of this growth factor in the abnormal processing of head pain in this pathological condition. Other members of the neurotrophin family, especially brain-derived neurotrophic factor (BDNF), have been hypothesized as being involved in the development of chronic head pain in patients affected by CDH, but so far no data are available on this subject. BDNF, NGF and glutamate levels were determined in the CSF of 25 patients affected by CDH with a previous history of migraine. These levels were compared with those of a group of 20 control subjects, for whom the CSF examination and other instrumental investigations excluded diseases of the central and peripheral nervous systems. Significantly higher levels of BDNF, NGF and glutamate were found in CDH patients compared with control subjects (p<0.0001, p<0.0002 and p<0.001, respectively). A significant positive correlation emerged between CSF values of BDNF and those of NGF (r=0.61, p<0.001) and glutamate (r=0.44, p<0.025) in CDH patients. No significant differences were detected in BDNF, NGF and glutamate levels between CDH patients with analgesic overuse and those without. These results support the involvement of BDNF in CDH through the potentiation of glutamatergic transmission involved in the processing of head pain. The significant correlation between BDNF and NGF levels suggests that NGF-mediated up-regulation of BDNF in central sites involved in long-term sensitization plays a key role in persistent head pain in CDH patients. Correspondence to P. Sarchielli  相似文献   
5.
Dermatoglyphics in von Recklinghausen neurofibromatosis   总被引:2,自引:0,他引:2  
We studied dermatoglyphic traits in 27 patients (12 males and 15 females) with neurofibromatosis type I (NF-1) to verify which characteristics may be considered typical of this disorder. The frequency of digital central pockets in the patients was significantly greater than in control individuals (P less than .005), but when we evaluated the sexes separately, the difference was significant only among females (P less than .002). The distribution of central pockets on the various fingers was significantly different in affected females, compared with normal controls, but only on fingers II (P less than .05), IV (P .002), and V (P less than .05). The quantitative finger tip pattern values and the total finger ridge count (TFRC) were always higher in the patients, as well as was the a-b ridge count. The latter was significantly increased only on the right hand in females (P less than .01). Among the patients, the atd angle values were increased on both hands of females and on the right hand in males, whereas both the ulnar index A'-d and the a-t' ridge counts were diminished. The frequency of high endings (5' or 5") of line A was increased in NF-1 patients on both hands. Like in previous investigations, our patients showed an increased number of secondary creases, limited to II degree according to Vormittag et al. [1986] (P less than .048). Our results only partially confirmed prior data. Therefore, we think that there is no typical dermatoglyphic pattern in NF-1 and that this parameter is not a diagnostic indicator in this disorder.  相似文献   
6.
7.
We have investigated the role of the purinergic P2X7 receptor in the formation of multinucleated giant cells in human monocyte/macrophage cultures stimulated with either concanavalin A or phytohemagglutinin. Macrophage fusion can be blocked by a P2X7-selective pharmacological antagonist or by a mAb directed against the extracellular P2X7 domain. Furthermore, macrophage cell clones expressing high P2X7 levels spontaneously fuse in culture, whereas macrophage clones lacking P2X7 are unable to fuse. Our findings suggest that the newly identified purinergic P2X7 receptor plays a central role in the complex chain of events leading to generation of macrophage-derived giant cells.  相似文献   
8.
9.
A cytogenetic study on 25 breast fibroadenomas from 17 women is reported. Seven tumors in five patients showed clonal structural chromosome changes. In three patients the breaks involved chromosome 12, occurring in two tumors in band 12p12 and in band 12q15 in all three tumors of one patient. The finding of an identical aberration, t(11;12)(q21;q15), in three adenomas from the same patient strongly suggests a clonal origin of multiple fibroadenomas of the breast.  相似文献   
10.
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