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   1533篇
  免费   121篇
  国内免费   27篇
耳鼻咽喉   20篇
儿科学   59篇
妇产科学   22篇
基础医学   173篇
口腔科学   22篇
临床医学   105篇
内科学   327篇
皮肤病学   14篇
神经病学   71篇
特种医学   154篇
外科学   268篇
综合类   61篇
预防医学   48篇
眼科学   123篇
药学   102篇
肿瘤学   112篇
  2023年   9篇
  2022年   12篇
  2021年   26篇
  2020年   19篇
  2019年   24篇
  2018年   44篇
  2017年   17篇
  2016年   21篇
  2015年   33篇
  2014年   41篇
  2013年   51篇
  2012年   83篇
  2011年   107篇
  2010年   59篇
  2009年   56篇
  2008年   65篇
  2007年   83篇
  2006年   79篇
  2005年   59篇
  2004年   71篇
  2003年   56篇
  2002年   43篇
  2001年   49篇
  2000年   43篇
  1999年   41篇
  1998年   49篇
  1997年   33篇
  1996年   36篇
  1995年   32篇
  1994年   29篇
  1993年   33篇
  1992年   35篇
  1991年   19篇
  1990年   26篇
  1989年   26篇
  1988年   23篇
  1987年   17篇
  1986年   20篇
  1985年   15篇
  1984年   12篇
  1983年   10篇
  1982年   13篇
  1981年   13篇
  1980年   16篇
  1979年   4篇
  1978年   4篇
  1977年   4篇
  1976年   5篇
  1975年   4篇
  1973年   3篇
排序方式: 共有1681条查询结果,搜索用时 15 毫秒
41.
42.
43.
OBJECTIVE—To assess the efficacy and complications of device occlusion of atrial septal defects in adults, using the Amplatzer septal occluder (ASO).
DESIGN—A prospective interventional study.
SETTING—Paediatric cardiology departments in two European teaching hospitals.
PATIENTS—The first 20 patients accepted for atrial septal defect device occlusion, on the basis of transoesophageal echocardiography. Sixteen patients had larger defects with right heart dilatation, while the primary indication for closure in four was a history of early paradoxical embolism.
INTERVENTIONS—Transcatheter atrial septal defect occlusions performed under transoesophageal echocardiography and fluoroscopic guidance between December 1996 and June 1998.
OUTCOME MEASURES—Success of deployment of ASO devices, procedure and fluoroscopic times, complications, and symptoms.
RESULTS—The ASO device was successfully implanted in all 20 patients (14 female), median age 44.2 years, with no complications. Of the 16 patients with right heart dilatation, the median Qp:Qs was 2.5:1. Defects measured 11-22 mm (median 18) on transoesophageal echocardiography, with balloon sized diameter (and device size) of 13-28 mm (median 20). For all 20 patients, the procedure time ranged from 38-78 minutes (median 61), and fluoroscopy 8.4-24.7 minutes (median 15.2). There were residual shunts in three patients at the end of the procedure, which were trivial ( 1 mm) as assessed by transoesophageal echocardiography, and persisted for more than six months in only one patient. Follow up ranged from 0.1-1.5 years (median 0.7). There have been no late complications.
CONCLUSIONS—The ASO device can be used successfully to close selected oval fossa defects in adults, with minimal procedural morbidity and excellent early results.


Keywords: atrial septal defect; interventional cardiac catheterisation; Amplatzer septal occluder  相似文献   
44.
Platelet glycoproteins IIb and IIIa as a calcium channel in liposomes   总被引:3,自引:0,他引:3  
Rybak  ME; Renzulli  LA; Bruns  MJ; Cahaly  DP 《Blood》1988,72(2):714-720
Human platelet membrane glycoproteins IIb and IIIa (GPIIb and IIIa) were incorporated into phospholipid vesicles by the reverse-phase technique to assess the ability of GPIIb and IIIa to function as a Ca2+ channel. Movement of Ca2+ across the lipid bilayer was quantitated by injection of proteoliposomes with encapsulated Fura-2 into Ca2+ buffers and measurement of Fura-2 fluorescence as an indicator of Ca2+ influx. Reciprocally, to assess the function of proteins in an inside-out orientation, Ca2+-loaded vesicles were injected into Ca2+-free buffer and Ca2+ efflux monitored by a calcium electrode. Incorporation of the IIb-IIIa complex produced significant facilitation of Ca2+ movement across the lipid bilayer. No net transmembrane Ca2+ movement was seen with dissociated IIb and IIIa. Movement of Ca2+ was proportional to the transmembrane Ca2+ gradient. Ca2+ movement into the vesicles was inversely proportional to extravesicular NaCl from 25 to 150 mmol/L, analogous to several studies in the intact platelet. Adenosine triphosphate had no effect on Ca2+ movement into or out of the vesicles. Specific inhibition of a Ca2+ shift into the vesicles was seen with M148, a monoclonal antibody to IIb/IIIa, while no inhibition was observed with a panel of other anti-IIb/IIIa monoclonal antibodies. This suggests that a specific site on the complex or orientation of the complex is essential for calcium channel function. These data demonstrate that the GPIIb/IIIa complex can serve as a passive Ca2+ channel across a phospholipid bilayer and has the potential to play a role in Ca2+ flux across the platelet plasma membrane.  相似文献   
45.
46.

Objective

To adapt an observational tool for assessing patient-centeredness of radiotherapy consultations and to assess whether scores for this tool and an existing tool assessing patient-perceived patient-centeredness predict patient outcomes.

Methods

The Measure of Patient-Centered Communication (MPCC), an observational coding system that assesses depth of discussion during a consultation, was adapted to the radiotherapy context. Fifty-six radiotherapy patients (from 10 radiation therapists) had their psycho-education sessions recorded and coded using the MPCC. Patients also completed instruments assessing their perception of patient-centeredness, trust in the radiation therapist, satisfaction with the consultation, authentic self-representation (ASR) and state anxiety.

Results

The MPCC correlated weakly with patient-perceived patient-centeredness. The Feelings subcomponent of the MPCC predicted one aspect of ASR and trust, and interacted with level of therapist experience to predict trust. Patient-perceived patient-centeredness, which exhibited a ceiling effect, predicted satisfaction.

Conclusion

Patient-centered communication is an important predictor of patient outcomes in radiotherapy and obviates some negative aspects of radiation therapists’ experience on patient trust. As in other studies, there is a weak association between self-reported and observational coding of PCC.

Practice implications

Radiation therapists have both technical and supportive roles to play in patient care, and may benefit from training in their supportive role.  相似文献   
47.
48.
Background and Aims: Current histological scoring systems do not subclassify cirrhosis. Computer‐assisted digital image analysis (DIA) of Sirius Red‐stained sections measures fibrosis morphologically producing a fibrosis ratio (collagen proportionate area [CPA]). CPA could have prognostic value within a disease stage, such as cirrhosis. The aim of the present study was to evaluate CPA in patients with recurrent hepatitis C virus (HCV) allograft cirrhosis and assess its relationship with hepatic venous pressure gradient (HVPG). Methods: In 121 consecutively‐transplanted HCV patients with HVPG, measured contemporaneously with transjugular liver biopsies, 65 had Ishak stage 5 or 6 disease (43 with HVPG measurement). Biopsies were stained with Sirius Red for DIA, and the collagen content was expressed as a CPA. In three cases, a tissue for Sirius Red staining was not obtained, and the patients were excluded. Results: Sixty‐two patients were analyzed. The median HVPG was 8 mmHg (interquartile range [IQR]: 5–10). Portal hypertension (HVPG ≥ 6 < 10 mmHg) was present in 30 (69.8%), and HVPG ≥ 10 mmHg in 13 (30.2%). The median CPA was 16% (IQR 10.75–23.25). Median Child–Pugh score and HVPG were not significantly different between Ishak fibrosis stage 5 or 6, whereas CPA was statistically different: 13% in stage 5 (IQR 8.3–12.4) versus 23% in stage 6 (IQR 17–33.7, P < 0.001). In the multivariate analysis, CPA was the only variable significantly associated with clinically‐significant portal hypertension (HVPG ≥ 10 mmHg, odds ratio: 1.085, confidence interval: 1.004–1.172, P = 0.040). A CPA of 14% was the best cut‐off value for clinically‐significant portal hypertension (CSPH) and liver decompensation, which occurred in 24 patients. Event‐free survival was significantly shorter in patients with CSPH or with a CPA value ≥ 14%, or with a combination of both. Conclusion: In Ishak stages 5 and 6, CPA correlated with HVPG, but had a wider range of values, suggesting a greater sensitivity for distinguishing “early” from “late” severe fibrosis/cirrhosis. CPA was a unique, independent predictor of HVPG ≥ 10 mmHg. CPA can be used to subclassify cirrhosis and for prognostic stratification.  相似文献   
49.
Recombinant parathyroid hormone (rPTH) therapy has been evaluated for skeletal repair in animal studies and clinical trials based on its known anabolic effects, but its effects on angiogenesis and fibrosis remain poorly understood. We examined the effects of rPTH therapy on blood vessel formation and osseous integration in a murine femoral allograft model, which caused a significant increase in small vessel numbers, and decreased large vessel formation (p < 0.05). Histology showed that rPTH also reduced fibrosis around the allografts to similar levels observed in live autografts, and decreased mast cells at the graft‐host junction. Similar effects on vasculogenesis and fibrosis were observed in femoral allografts from Col1caPTHR transgenic mice. Gene expression profiling revealed rPTH‐induced angiopoietin‐1 (8‐fold), while decreasing angiopoietin‐2 (70‐fold) at day 7 of allograft healing. Finally, we show anti‐angiopoietin‐2 peptibody (L1‐10) treatment mimics rPTH effects on angiogenesis and fibrosis. Collectively, these findings show that intermittent rPTH treatment enhances structural allograft healing by two processes: (1) anabolic effects on new bone formation via small vessel angiogenesis, and (2) inhibition of angiopoietin‐2–mediated arteriogenesis. The latter effect may function as a vascular sieve to limit mast cell access to the site of tissue repair, which decreases fibrosis around and between the fractured ends of bone. Thus, rPTH therapy may be generalizable to all forms of tissue repair that suffer from limited biointegration and excessive fibrosis. © 2013 American Society for Bone and Mineral Research.  相似文献   
50.
Choroid plexus papillomas are rare neoplasms that arise from choroid plexus epithelium. The World Health Organization classification describes three histological grades. Grade I is choroid plexus papilloma, grade II is atypical choroid plexus papilloma and grade III is choroid plexus carcinoma. Progression between grades is rare but documented. We present two adult cases, a 53-year-old female and a 70-year-old male, who demonstrated clear interval histological progression from grade I choroid plexus papilloma to higher grades.  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