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   3117篇
  免费   109篇
  国内免费   46篇
耳鼻咽喉   13篇
儿科学   46篇
妇产科学   28篇
基础医学   281篇
口腔科学   72篇
临床医学   282篇
内科学   1080篇
皮肤病学   24篇
神经病学   135篇
特种医学   122篇
外科学   447篇
综合类   16篇
预防医学   56篇
眼科学   20篇
药学   284篇
中国医学   12篇
肿瘤学   354篇
  2023年   25篇
  2022年   56篇
  2021年   56篇
  2020年   41篇
  2019年   50篇
  2018年   53篇
  2017年   47篇
  2016年   70篇
  2015年   67篇
  2014年   74篇
  2013年   108篇
  2012年   152篇
  2011年   181篇
  2010年   87篇
  2009年   66篇
  2008年   138篇
  2007年   161篇
  2006年   178篇
  2005年   175篇
  2004年   204篇
  2003年   195篇
  2002年   203篇
  2001年   103篇
  2000年   93篇
  1999年   100篇
  1998年   48篇
  1997年   27篇
  1996年   50篇
  1995年   37篇
  1994年   38篇
  1993年   21篇
  1992年   43篇
  1991年   41篇
  1990年   39篇
  1989年   47篇
  1988年   23篇
  1987年   17篇
  1986年   22篇
  1985年   15篇
  1984年   17篇
  1983年   14篇
  1982年   7篇
  1981年   9篇
  1980年   9篇
  1979年   8篇
  1978年   6篇
  1977年   7篇
  1976年   5篇
  1974年   9篇
  1963年   3篇
排序方式: 共有3272条查询结果,搜索用时 531 毫秒
81.
82.
 Hepatocyte growth factor (HGF) is a unique growth factor with many protective functions. Previously, we demonstrated that HGF stimulated growth of endothelial cells without replication of vascular smooth muscle cells (VSMC) and that angiotensin (Ang) II significantly decreased local HGF production in VSMC. Moreover, we also reported that high glucose significantly decreased local vascular HGF production. Therefore, we examined effects of Ang II blockade on vascular HGF expression and endothelial injury in diabetic hypertensive rats. An angiotensin-converting enzyme inhibitor (quinapril) and an Ang II type 1 receptor antagonist (GA-0113) or vehicle was administrated to diabetic spontaneously hypertensive rats (SHR-DM), in whom diabetes was induced by streptozotocin. Endothelial function was evaluated by the vasodilator response to acetylcholine, and the expression of vascular HGF and its receptor, c-met, was examined by immunohistochemistry. Both quinapril and GA-0113 significantly improved the vasodilator response to acetylcholine (P < 0.01), while vehicle did not as compared to untreated normotensive Wistar-Kyoto rats (WKY). We next examined the effects of Ang II blockade on vascular HGF expression in SHR-DM. Importantly, the vascular HGF level was markedly decreased in SHR-DM as compared to WKY, while Ang II blockade by quinapril or GA-0113 significantly increased positive staining for HGF in SHR-DM. Similarly, staining of its specific receptor, c-met, was less in the blood vessels of SHR-DM as compared to WKY. In contrast, Ang II blockade also significantly increased c-met production in SHR-DM. The present data demonstrated the improvement of endothelial dysfunction by Ang II blockade in SHR-SM, accompanied by an increase in vascular HGF and c-met. Received: June 7, 2002 / Accepted: September 21, 2002 Acknowledgments We wish to thank Rie Kosai and Keiko Yamaguchi for their excellent technical assistance. This work was partially supported by grants from the Japan Health Sciences Foundation, a Grant-in-Aid from The Ministry of Public Health and Welfare, a Grant-in-Aid for the Development of Innovative Technology, a Grant-in-Aid from Japan Promotion of Science, and through Special Coordination Funds of the Ministry of Education, Culture, Sports, Science and Technology, the Japanese Government. Correspondence to N. Tomita  相似文献   
83.
Dextran in lactated Ringer's solution (20 ml/kg) was infused for 1 hour into anesthetized dogs with sinoaortic denervation and vagotomy (deafferentation; n = 10) and dogs treated with hexamethonium (de-efferentation; n = 13) to compare with our previous observation in dogs with an intact autonomic nervous system (control, n = 34). During the infusion, increase in blood pressure associated with increase in cardiac output was observed in all three groups. The increases in blood pressure were larger in the two groups with an impaired autonomic nervous system. In the recovery period, the control dogs and the hexamethonium-treated dogs showed gradual increases in total peripheral resistance and in vasoconstricted hypertension 3 hours after stopping the infusion. In contrast, the dogs with sinoaortic denervation and vagotomy did not show any increase in total peripheral resistance. The vasoconstricted groups showed peaks of natriuresis soon after the infusion, not 3 hours after the infusion when vasoconstriction was observed, although the dogs with deafferentation did not show a significant increase in natriuresis. Norepinephrine (0.5 micrograms/kg) was administered intravenously before and after volume expansion, and the pressor responses in the three groups after volume expansion were enhanced similarly (143%, 128%, and 136%, respectively). These results indicate that the afferent signals from peripheral vessels to the brain contribute to the production of vasoconstricted hypertension after acute volume expansion and that the vasoconstriction is independent of pressor hypersensitivity and is dissociated in time from the natriuresis.  相似文献   
84.
A simplified direct radioimmunoassay for urinary acid labile aldosterone was developed. One ml of urine was hydrolysed with 2 ml of 0.2N HCL at 30 degrees C for 16hrs. One tenth ml of hydrolysed urine diluted 10 times with charcoal treated aldosterone-free calf serum was used for the radioimmunoassay. The radioimmunoasssay was done with a specific antibody, 125I-aldosterone, as the labeled antigen and polyethylene glycol for bound-free separation. There were excellent correlations between the present methods and other methods, i.e., i) a method using dichloromethane extraction before the assay as well as pre-extraction before hydrolysis and ii) a commercial kit using 3H-aldosterone. The intra-assay coefficient of variation was 5.8%, and the inter-assay coefficient of variation was 9.5%. The normal value of urinary aldosterone was excretion was 3.7 plus or minus 2.5 micrograms/day by the present method, and values of patients with primary aldosteronism were between 24 to 43 micrograms/day.  相似文献   
85.
INTRODUCTION: Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His-bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His-bundle in comparison with right ventricular outflow tract (RVOT)-VT/VPCs. METHODS AND RESULTS: Ninety RV-VT/VPC patients underwent catheter mapping and radiofrequency ablation. ECG variables were compared between VT/VPCs originating from the RVOT and near the His-bundle. Ten patients had foci near the His-bundle (HIS group), with the His-bundle local ventricular electrogram preceding the QRS onset by 15-35 msec (mean: 22 msec) and His-bundle pacing produced a nearly identical ECG to clinical VT/VPCs. The HIS group R wave amplitude in the inferior leads (lead III: 1.0 +/- 0.6 mV) was significantly lower than that of the RVOT group (1.7 +/- 0.4 mV, P < 0.05). An R wave in aVL was present in 6 of 10 HIS group patients, while almost all RVOT group patients had a QS pattern in aVL. Lead I in HIS group exhibited significantly taller R wave amplitudes than RVOT group. HIS group QRS duration in the inferior leads was shorter than that of the RVOT group. Eight of 10 HIS group patients exhibited a QS pattern in lead V1 compared to 14 of 81 RVOT group patients. HIS group had larger R wave amplitudes in leads V5 and V6 than RVOT group. CONCLUSION: VT/VPCs originating near the His-bundle have distinctive ECG characteristics. Knowledge of the characteristic QRS morphology may facilitate catheter mapping and successful ablation.  相似文献   
86.
87.
The aim of this study was to elucidate whether fecoflowmetry (FFM) could evaluate more detailed evacuative function than anorectal manometry by comparing between FFM or anorectal manometric findings and the clinical questionnaires and the types of surgical procedure in the patients who received anal-preserving surgery. Fifty-three patients who underwent anal-preserving surgery for low rectal cancer were enrolled. The relationships between FFM or the manometric findings and the clinical questionnaires and the types of procedure of anal-preserving surgery were evaluated. There were significant differences between FFM markers and the clinical questionnaire and the types of the surgical procedure, whereas no significant relationship was observed between the manometric findings and the clinical questionnaire and the types of the surgical procedure. FFM might be feasible and useful for the objective assessment of evacuative function and may be superior to manometry for patients undergoing anal-preserving surgery.Key words: Anorectal manometry, Anal-preserving surgery, Fecoflowmetry, Incontinence, Rectal cancerSphincter preservation has been one of the key issues of rectal cancer surgery. Low anterior resection (LAR)1 and internal and external sphincter resection (ISR and ESR) are anal-preserving surgeries.2,3 The aim of these procedures is to restore the normal process of defecation, along with its function, and to improve the quality of life of patients by avoiding permanent colostomy. However, anal-preserving surgery is often associated with evacuative dysfunction and various degrees of incontinence.47Most studies that have assessed the evacuation function have used clinical questionnaires, which are subjective and may vary according to the patient perception.7 There are many factors that can affect the evacuative function, such as the stool consistency, rectal capacity, anal sphincters, pelvic floor muscles, and intra-abdominal pressure. Although manometry with or without the clinical score has also commonly been used, fecoflowmetry (FFM) has been reported to be more accurate and useful for assessing the postoperative anorectal motor function.813 FFM was first introduced by Shafik and is a dynamic method for examining the anorectal motor activity that simulates the natural act of defecation.14 Some studies have shown its usefulness in postoperative patients with anorectal disease,811 but only a few studies have been performed to examine the evacuative function following anal-preserving surgery.12,13 The aim of this study was to evaluate the evacuative function in the postoperative period following anal-preserving surgery in patients with low rectal cancer using FFM, and to compare the results with the Wexner score and anorectal manometry.15  相似文献   
88.
AIM: Human beta-defensin (HBD)-1 and HBD-2 are endogenous antimicrobial peptides. Unlike HBD-1, the HBD-2 expression is augmented by Helicobacter pylori (H pylori). We sought to determine HBD-1 and HBD-2 concentrations in gastric juice during H pylori infection. METHODS: HBD-1 and HBD-2 concentrations were measured by radioimmunoassay in plasma and gastric juice of 49 H pylori-infected and 33 uninfected subjects and before and after anti-H pylori treatment in 13 patients with H pylori-associated gastritis. Interleukin (IL)-1beta and IL-8 concentrations in gastric juice were measured by enzyme-linked immunosorbent assay (ELISA). Histological grades of gastritis were determined using two biopsy specimens taken from the antrum and corpus. Reverse phase high performance liquid chromatography (RP-HPLC) was used to identify HBD-2. RESULTS: HBD-2 concentrations in gastric juice, but not in plasma, were significantly higher in H pylori-positive than -negative subjects, albeit the post-treatment levels were unchanged. Immunoreactivity for HBD-2 was exclusively identified in H pylori-infected mucosa by RP-HPLC. HBD-2 concentrations in gastric juice correlated with histological degree of neutrophil and mononuclear cell infiltration in the corpus. IL-1beta levels correlated with those of IL-8, but not HBD-2. Plasma and gastric juice HBD-1 concentrations were similar in H pylori-infected and uninfected subjects. CONCLUSION: Our results place the beta-defensins, especially HBD-2, in the front line of innate immune defence. Moreover, HBD-2 may be involved in the pathogenesis of H pylori-associated gastritis, possibly through its function as immune and inflammatory mediator.  相似文献   
89.
[Purpose] The difficulty levels of level-2 OSCE (examination and measurement skills) items were examined, with a view to providing reference data for the determination of students’ skills. [Subjects] A total of 284 graduates of physical (PT) and occupational (OT) therapy classes of 2011 (59 and 40), 2012 (46 and 36), and 2013 (61 and 42, respectively) were studied, with PT or OT faculty members as OSCE examiners and a simulated patient. [Methods] Scores for 11 level-2 OSCE items were compared between before and after clinical training. [Results] Scores markedly increased after clinical training. On comparison among the items, scores for sensory examination were the highest, and those for interviews were the lowest. [Conclusion] The results of this study indicate the necessity of considering an appropriate combination of different difficulty levels when adopting OSCE-based educational approaches.Key words: OSCE, Clinical skill, Physical and occupational therapists  相似文献   
90.
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