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   508篇
  免费   47篇
  国内免费   6篇
耳鼻咽喉   1篇
儿科学   15篇
妇产科学   7篇
基础医学   33篇
口腔科学   28篇
临床医学   48篇
内科学   105篇
皮肤病学   8篇
神经病学   20篇
特种医学   104篇
外科学   47篇
综合类   66篇
预防医学   36篇
眼科学   6篇
药学   18篇
中国医学   4篇
肿瘤学   15篇
  2023年   2篇
  2022年   6篇
  2021年   11篇
  2020年   7篇
  2019年   6篇
  2018年   16篇
  2017年   13篇
  2016年   11篇
  2015年   16篇
  2014年   18篇
  2013年   29篇
  2012年   22篇
  2011年   24篇
  2010年   42篇
  2009年   29篇
  2008年   18篇
  2007年   19篇
  2006年   23篇
  2005年   12篇
  2004年   8篇
  2003年   9篇
  2002年   4篇
  2001年   5篇
  2000年   12篇
  1999年   5篇
  1998年   15篇
  1997年   17篇
  1996年   17篇
  1995年   15篇
  1994年   15篇
  1993年   16篇
  1992年   2篇
  1991年   3篇
  1990年   4篇
  1989年   10篇
  1988年   8篇
  1987年   7篇
  1986年   6篇
  1985年   11篇
  1984年   5篇
  1983年   4篇
  1982年   2篇
  1981年   8篇
  1980年   4篇
  1979年   3篇
  1978年   3篇
  1977年   5篇
  1976年   5篇
  1975年   7篇
  1968年   1篇
排序方式: 共有561条查询结果,搜索用时 15 毫秒
41.
Modified Pulmonary Vein Isolation in AF Ablation. Introduction: Pulmonary vein isolation (PVI) is the primary ablation therapy in patients with atrial fibrillation (AF). We hypothesized that high dominant frequency (DF) sites (AF nests during sinus rhythm [SR]) adjacent to the PV ostia are associated with the atrial substrate that maintains AF, and PVI incorporating the high‐frequency AF nests may have a higher efficacy. Methods and Results: In a prospective and randomized comparison, 126 symptomatic paroxysmal AF patients that underwent PVI were enrolled. We compared the efficacy of a modified PVI (ablation line: 1.0–1.5 cm from the PV ostium with encircling the AF nests [spectral analysis with DF >70 Hz during SR, Group II]) versus the anatomy‐guided conventional PVI (Group I). In Group II, the DF value along the PV ostium was lower than 70 Hz after the PVI. The primary endpoint was the freedom from symptomatic atrial arrhythmias after a single procedure. We also followed the autonomic function by a time‐domain analysis of the heart rate variability. In both groups, AF nests were observed and electric isolation was successfully obtained in all patients. With a mean duration of 16 ± 6.1 months of follow‐up, Group II had a higher single procedure efficacy without drugs (78.7% vs 66.1%, log‐rank test: P = 0.02), and fewer repeat procedures (6.6% vs 23%; P = 0.04), as compared to Group I. Conclusion: PVI incorporating the high frequency AF nests adjacent to the PV ostia had a better single procedure efficacy. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1155–1162, November 2012)  相似文献   
42.
Kuypers  FA; Lubin  BH; Yee  M; Agre  P; Devaux  PF; Geldwerth  D 《Blood》1993,81(4):1051-1057
In the human erythrocyte membrane phosphatidylcholine and sphingomyelin reside mainly in the outer leaflet, whereas the aminophospholipids, phosphatidylethanolamine and phosphatidylserine, are mainly found in the inner leaflet. Maintenance of phospholipid asymmetry has been assumed to involve interactions between the aminophospholipids and the membrane skeleton, in particular spectrin. To investigate whether spectrin contributes to maintaining the phospholipid transbilayer distribution and kinetics of redistribution, we studied erythrocytes from hereditary spherocytosis patients whose spectrin levels ranged from 34% to 82% of normal. The phospholipid composition and the accessibility of membrane phospholipids to hydrolysis by phospholipases were in the normal range. Spin-labeled phosphatidylserine and phosphatidylethanolamine analogues that had been introduced into the outer leaflet were rapidly transported at 37 degrees C to the inner leaflet, whereas the redistribution of spin-labeled phosphatidylcholine was slower. The kinetics of transbilayer movement of these spin-labeled phospholipid in all samples was in the normal range and was not affected by the level of spectrin. Although these erythrocyte membranes contained as little as 34% of the normal level of spectrin and were characterized by several physical abnormalities, the composition, distribution, and transbilayer kinetics of the phospholipids were found to be normal. We therefore conclude that spectrin plays, at best, only a minor role in maintaining the distribution of erythrocyte membrane phospholipid.  相似文献   
43.
FA Chiafari  ; RE Wenk 《Transfusion》1990,30(7):648-650
Single-locus DNA probes for tandem repeat sequences are now used in conjunction with particular endonucleases to characterize heritable restriction fragment lengths in parentage tests. Southern blots of this type, however, demonstrate only two attributes of an allele: its length and the presence of nucleotide sequences that are complementary to the probe. Not all restriction fragments of the same apparent length that react with the same probe are identical. Differences between comigrating fragments can be detected by the selection of a restriction enzyme that recognizes sites in a subset of the repeat sequences, and the information content of these loci is therefore increased. This report describes a paternity case in which two brothers appeared, after DNA phenotyping using Hinf I, to be the father. A second phenotyping using Hae III excluded one of the brothers.  相似文献   
44.
BACKGROUND: Osteopenia with decreased bone mineral density (BMD) is a frequent finding in renal allograft recipients. Data concerning the bone architecture in these patients do not exist, however. METHODS: We compared the bone architecture of 33 randomly assigned women (age 49 +/- 12 years), who had received renal allografts 5.6 +/- 5.3 years before the investigation, with 74 women (age 50 +/- 14 years) who were admitted for osteodensitometry. All patients underwent single-energy computed tomography (SEQCT) and a midvertebral high-resolution tomography with computer-assisted analysis of the trabecular vertebral body architecture. RESULTS: Progressive alteration of bone architecture was associated with increasing vertebral height loss of the vertebral body. Height reduction of a vertebral body of more than 15% was associated with a significantly lower BMD (-2.3 +/- 0.8 versus -1.1 +/- 1.1 standard deviations below normal BMD), a lower trabecular bone area (13 +/- 8% versus 42 +/- 22%) and a lower trabecular diameter (1.4 +/- 0.5 mm versus 2.2 +/- 0.8 mm) compared to recipients without height reduction. In comparison to a matched group of patients with similarly reduced BMD (1.1 +/- 1.2 versus 1.2 +/- 1.1 SD below normal BMD), renal allograft recipients showed a lower number of trabecular plates (5.6 +/- 3.1 versus 7.0 +/- 3.7) and a smaller intertrabecular surface (54 +/- 116 mm versus 75 +/- 138 mm). CONCLUSIONS: Alterations of bone architecture in renal allograft recipients were associated with progressive vertebral height loss. Despite similar bone mineral density, differences of bone architecture could be observed between renal allograft recipients and patients with osteoporosis.   相似文献   
45.
目的总结在体外循环辅助下,经右房切口治疗合并下腔静脉血栓形成的布-加氏综合征的治疗经验。方法回顾我院自2002年9月至2010年7月共计49例在体外循环辅助下,经右心房切口治疗合并下腔静脉血栓的布加氏综合征的临床病例和随访资料。结果全组病人均成功的在体外循环辅助下完成经右房切口下腔静脉狭窄段扩张及血栓取出术。术中在手指破膜后再使用3.0×4.0cm球囊进行扩张。围手术期病人无死亡,无急性肺栓塞等严重并发症的发生。术后随访0~36个月,所有病人术后症状明显缓解,腹水及下肢水肿减轻至消失。1例病人术后1年后出现再狭窄,经股静脉行下腔静脉球囊扩张后好转。全组病人术后随访未见有血栓形成。结论在体外循环下,经右房切口对于合并下腔静脉血栓的布-加氏综合征是一种安全有效的治疗方法。  相似文献   
46.
47.
本文对药物流产时在不同时间加用不同剂量的紫草对药物流产效果的影响进行探索。紫草的加用时间为米索前列醇 (简称米索 )应用前 3d、后 3d及前后共 6 d,剂量分别为 5 0 g、75 g和 1 0 0 g。 1 35 0例早孕妇女分成 9个研究组进行观察。结果表明 :在米索应用前 3d和前后 6 d加用紫草效果较米索应用后 3d加用紫草在完全流产率和出血时间两方面效果明显改善 (P均 <0 .0 5 )。紫草用量 5 0~ 1 0 0 g时流产效果与紫草剂量无明显相关。因此我们认为药物流产时在应用米索前紫草与米非司酮同时应用效果较好 ,剂量以5 0 g较为合理  相似文献   
48.
SummaryPurpose In order to improve the survival of patients with a glioblastoma multiforme tumor (GBM), new therapeutic strategies must be developed. The use of a death inducing ligand such as TRAIL (TNF Related Apoptosis Inducing Ligand) seems a promising innovative therapy. The aim of this study was to quantify the expression of the death regulating receptors TRAIL-R1, TRAIL-R2 and TRAIL on primary GBM specimens and to correlate this expression with survival.Experimental design Expression of TRAIL and TRAIL-receptors was assessed by immunohistochemistry, both quantitatively (% of positive tumor cells) and semi-quantitatively (staining intensity) within both the perinecrotic and intermediate tumor zones of primary GBM specimens. RT-PCR of GBM tissue was performed to show expression of TRAIL receptor mRNA.Results Immunohistochemistry showed a slight diffuse intracytoplasmic and a stronger membranous staining for TRAIL and TRAIL receptors in tumor cells. Semi-quantitative expression of TRAIL showed a significantly higher expression of TRAIL in the perinecrotic zone than in the intermediate zone of the tumor (P=0.0001). TRAIL-R2 expression was significantly higher expressed than TRAIL-R1 (P=0.005). The antigenic load of TRAIL-R2 was positively correlated with survival (P=0.02). Multivariate analysis of TRAIL-R1 within the study group (n=62) showed that age, gender, staining intensity, antigenic load, % of TRAIL-R1 expression, were not statistically correlated with survival however radiotherapy was significantly correlated (multivariate analysis: age: P=0.15; gender: P=0.64; staining intensity: P=0.17; antigenic load: P=0.056; % of TRAIL-R1 expression: P=0.058; radiotherapy: P=0.0001). Subgroup analysis of patients who had received radiotherapy (n=47) showed a significant association of % of TRAIL-R1 expression and the antigenic load of TRAIL-R1 with survival (multivariate analysis: P=0.036, respectively, P=0.023).Multivariate analysis of TRAIL-R2 staining intensity and antigenic load, within the study group (P=0.004, respectively, P=0.03) and the subgroup (P=0.002, respectively, P=0.004), showed a significant association with survival. RT-PCR analysis detected a negative relation between the amount of TRAIL-R1 mRNA and the WHO grade of astrocytic tumors (P=0.03).Conclusions TRAIL-R1 and TRAIL-R2 expression on tumor cells are independent prognostic factors for survival in patients with a glioblastoma multiforme. Both receptors could be targets for TRAIL therapy. As TRAIL-R2 is more expressed, in comparison with TRAIL-R1, on GBM tumor cells, TRAIL-R2 seems to be of more importance as a target for future TRAIL therapy than TRAIL-R1.  相似文献   
49.
50.
Recent progress in oculomotor research has enabled new insights into the functional neuroanatomy of the human premotor oculomotor brainstem network. In the present review, we provide an overview of its functional neuroanatomy and summarize the broad range of oculomotor dysfunctions that may occur in Huntington's disease (HD) patients. Although some of these oculomotor symptoms point to an involvement of the premotor oculomotor brainstem network in HD, no systematic analysis of this functional system has yet been performed in brains of HD patients. Therefore, its exact contribution to oculomotor symptoms in HD remains unclear. A possible strategy to clarify this issue is the use of unconventional 100-µm-thick serial tissue sections stained for Nissl substance and lipofuscin pigment (Nissl-pigment stain according to Braak). This technique makes it possible to identify the known nuclei of the premotor oculomotor brainstem network and to study their possible involvement in the neurodegenerative process. Studies applying this morphological approach and using the current knowledge regarding the functional neuroanatomy of this human premotor oculomotor brainstem network will help to elucidate the anatomical basis of the large spectrum of oculomotor dysfunctions that are observed in HD patients. This knowledge may aid clinicians in the diagnosis and monitoring of the disease.  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