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   1595篇
  免费   95篇
  国内免费   15篇
耳鼻咽喉   37篇
儿科学   38篇
妇产科学   41篇
基础医学   254篇
口腔科学   28篇
临床医学   153篇
内科学   424篇
皮肤病学   24篇
神经病学   114篇
特种医学   69篇
外科学   294篇
综合类   8篇
预防医学   56篇
眼科学   19篇
药学   82篇
肿瘤学   64篇
  2024年   1篇
  2023年   16篇
  2022年   35篇
  2021年   53篇
  2020年   24篇
  2019年   51篇
  2018年   54篇
  2017年   52篇
  2016年   68篇
  2015年   55篇
  2014年   68篇
  2013年   93篇
  2012年   117篇
  2011年   139篇
  2010年   63篇
  2009年   73篇
  2008年   123篇
  2007年   109篇
  2006年   108篇
  2005年   88篇
  2004年   84篇
  2003年   94篇
  2002年   58篇
  2001年   12篇
  2000年   6篇
  1999年   9篇
  1998年   14篇
  1997年   5篇
  1996年   4篇
  1995年   3篇
  1994年   7篇
  1993年   1篇
  1992年   2篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1982年   2篇
  1980年   2篇
排序方式: 共有1705条查询结果,搜索用时 562 毫秒
71.

INTRODUCTION

Left-sided gallbladder is a rare anatomical variation. Usually it is discovered intra-operatively and is accompanied by anatomic variations that can prove quite challenging during laparoscopy.

PRESENTATION OF CASE

From a total of almost 3000 laparoscopic cholecystectomies performed in our institution, two cases of left sided gallbladder were unexpectantly identified intraoperatively. There were no indications for the ectopy preoperatively. In both cases modifications of the standard laparoscopic technique were mandatory. They were performed safely with no post-operative complications. Modifications consisted of transposition of the subxiphoid entry port and alteration in the direction of traction of the rest of the graspers. A review of the literature for methods of safe laparoscopic cholecystectomy was conducted.

DISCUSSION

The surgeon must be aware of the anatomic variances in the rare occasion of a left sided gallbladder, since preoperative diagnosis is very difficult.

CONCLUSION

Knowledge of potential hazards and modifications of laparoscopic technique is mandatory in order to avoid complications.  相似文献   
72.
73.

Purpose

Rheumatoid arthritis (RA) patients display high levels of oxidative stress. Transient exercise-induced increases in oxidative stress are thought to be adaptive in healthy populations. This study investigated the effect of exercise on markers of oxidative stress in RA, following acute exercise and a period of exercise training.

Methods

Acute exercise study: RA patients (N = 12, age: 56 ± 11) undertook a bout of exercise (30–40 min, 70 % VO2MAX), and blood samples were taken before and after exercise to assess markers of oxidative stress. Training study: RA patients (N = 19, age: 56 ± 10) were randomised into either a control or exercise group, who undertook 3 exercise sessions per week (30–40 min @70 % VO2MAX) for 3 months. Plasma markers of oxidative stress (protein carbonyls (PC), lipid hydroperoxides (LOOH), 3-nitrotyrosine (3-NT), total antioxidant capacity (TAC) and catalase (CAT) activity), inflammation (interleukin-8 (IL-8) and C-reactive protein (CRP)) and nitric oxide metabolites (NOx) were assessed before and after training.

Results

Acute exercise study: Protein carbonyls (PC) (+18 %) and NOx (+27 %) were significantly increased following exercise. Training study: 3-nitrotyrosine (3-NT) decreased (2.18 ± 1.78 to 1.10 ± 0.93 μM) in the exercise group only, alongside increases in aerobic fitness (24.45 ± 4.98 to 27.10 ± 4.51 ml/kg/min?1) and reductions in disease activity score (DAS: 3.47 ± 1.17 to 2.88 ± 0.76). PC, LOOH, TAC, IL-8, CRP and NOx concentrations, and CAT activity were unchanged in both groups.

Conclusions

Aerobic exercise training did not increase markers of oxidative stress in RA patients. 3-Nitrotyrosine and disease activity were decreased following exercise training.  相似文献   
74.
75.
76.
77.
Rocco Marchitelli  Ludovico Minati  Moira Marizzoni  Beatriz Bosch  David Bartrés‐Faz  Bernhard W. Müller  Jens Wiltfang  Ute Fiedler  Luca Roccatagliata  Agnese Picco  Flavio Nobili  Oliver Blin  Stephanie Bombois  Renaud Lopes  Régis Bordet  Julien Sein  Jean‐Philippe Ranjeva  Mira Didic  Hélène Gros‐Dagnac  Pierre Payoux  Giada Zoccatelli  Franco Alessandrini  Alberto Beltramello  Núria Bargalló  Antonio Ferretti  Massimo Caulo  Marco Aiello  Carlo Cavaliere  Andrea Soricelli  Lucilla Parnetti  Roberto Tarducci  Piero Floridi  Magda Tsolaki  Manos Constantinidis  Antonios Drevelegas  Paolo Maria Rossini  Camillo Marra  Peter Schönknecht  Tilman Hensch  Karl‐Titus Hoffmann  Joost P. Kuijer  Pieter Jelle Visser  Frederik Barkhof  Jorge Jovicich 《Human brain mapping》2016,37(6):2114-2132
Understanding how to reduce the influence of physiological noise in resting state fMRI data is important for the interpretation of functional brain connectivity. Limited data is currently available to assess the performance of physiological noise correction techniques, in particular when evaluating longitudinal changes in the default mode network (DMN) of healthy elderly participants. In this 3T harmonized multisite fMRI study, we investigated how different retrospective physiological noise correction (rPNC) methods influence the within‐site test‐retest reliability and the across‐site reproducibility consistency of DMN‐derived measurements across 13 MRI sites. Elderly participants were scanned twice at least a week apart (five participants per site). The rPNC methods were: none (NPC), Tissue‐based regression, PESTICA and FSL‐FIX. The DMN at the single subject level was robustly identified using ICA methods in all rPNC conditions. The methods significantly affected the mean z‐scores and, albeit less markedly, the cluster‐size in the DMN; in particular, FSL‐FIX tended to increase the DMN z‐scores compared to others. Within‐site test‐retest reliability was consistent across sites, with no differences across rPNC methods. The absolute percent errors were in the range of 5–11% for DMN z‐scores and cluster‐size reliability. DMN pattern overlap was in the range 60–65%. In particular, no rPNC method showed a significant reliability improvement relative to NPC. However, FSL‐FIX and Tissue‐based physiological correction methods showed both similar and significant improvements of reproducibility consistency across the consortium (ICC = 0.67) for the DMN z‐scores relative to NPC. Overall these findings support the use of rPNC methods like tissue‐based or FSL‐FIX to characterize multisite longitudinal changes of intrinsic functional connectivity. Hum Brain Mapp 37:2114–2132, 2016. © 2016 Wiley Periodicals, Inc.  相似文献   
78.
Total joint replacement is a highly successful surgical procedure for treatment of patients with disabling arthritis and joint dysfunction. However, over time, with high levels of activity and usage of the joint, implant wear particles are generated from the articulating surfaces. These wear particles can lead to activation of an inflammatory reaction, and subsequent bone resorption around the implant (periprosthetic osteolysis). Cells of the monocyte/macrophage lineage orchestrate this chronic inflammatory response, which is dominated by a pro-inflammatory (M 1) macrophage phenotype rather than an anti-inflammatory pro-tissue healing (M2) macrophage phenotype. While it has been shown that interleukin-4 (IL-4) selectively polarizes macrophages towards an M2 anti-inflammatory phenotype which promotes bone healing, rather than inflammation, little is known about the time course in which this occurs or conditions in which repolarization through I L-4 is most effective. The goal of this work was to study the time course of murine macrophage polarization and cytokine release in response to challenge with combinations of polymethyl methacrylate (PMMA) particles, lipopolysaccharide (LPS) and IL-4 in vitro. Treatment of particle-challenged monocyte/macrophages with IL-4 led to an initial suppression of pro-inflammatory cytokines and inducible nitric oxide synthase (iNOS) production and subsequent polarization into an M2 anti-inflammatory phenotype. This result was optimized when IL-4 was delivered before PMMA particle challenge, to an M 1 phenotype rather than to uncommitted (MO) macrophages. The effects of this polarization were sustained over a 5-day time course. Polarization of M1 macrophages into an M2 phenotype may be a strategy to mitigate wear particle associated periprosthetic osteolysis.  相似文献   
79.

Introduction

Duodenal neuroendocrine tumors (NETs) are rare neoplasms with poorly defined management. We sought to evaluate the outcomes of patients undergoing resection of duodenal NETs.

Methods

Using a multi-institutional database, 146 patients who underwent resection for duodenal NETs between 1993 and 2015 were identified. Data on clinicopathologic characteristics and outcomes were collected and analyzed.

Results

Local surgical resection (LR) was performed in 57 (39.0 %) patients, while 50 (34.3 %) patients underwent pancreaticoduodenectomy (PD) and 39 (26.7 %) patients an endoscopic resection (ER). Factors associated with worse RFS included advanced tumor grade and metastasis at diagnosis (both P?<?0.05) but not procedure type (P?>?0.05). Among patients who had at least one lymph node examined (n?=?85), 50 (58.8 %) had a metastatic lymph node; lymph node metastasis (P?=?0.04) and advanced tumor grade (P?=?0.04) were more common among patients with tumors >1.5 cm. Median length-of-stay was longer for PD versus LR (P?<?0.001). PD patients were at increased risk for severe postoperative complications (P?=?0.01).

Conclusion

Recurrence of duodenal NETs was dependent on tumor biology rather than procedure type. PD was associated with a longer hospital stay and higher risk of perioperative complications. For patients with tumors ≤1.5 cm, LR or ER may be appropriate with PD reserved for larger lesions and those not amenable to a more local approach.
  相似文献   
80.
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