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   2507篇
  免费   139篇
  国内免费   22篇
耳鼻咽喉   14篇
儿科学   82篇
妇产科学   23篇
基础医学   240篇
口腔科学   82篇
临床医学   233篇
内科学   580篇
皮肤病学   56篇
神经病学   196篇
特种医学   81篇
外科学   324篇
综合类   52篇
一般理论   2篇
预防医学   173篇
眼科学   122篇
药学   230篇
中国医学   30篇
肿瘤学   148篇
  2023年   30篇
  2022年   61篇
  2021年   89篇
  2020年   88篇
  2019年   112篇
  2018年   136篇
  2017年   89篇
  2016年   95篇
  2015年   101篇
  2014年   156篇
  2013年   161篇
  2012年   258篇
  2011年   252篇
  2010年   112篇
  2009年   95篇
  2008年   151篇
  2007年   159篇
  2006年   95篇
  2005年   91篇
  2004年   55篇
  2003年   48篇
  2002年   31篇
  2001年   14篇
  2000年   9篇
  1999年   12篇
  1998年   10篇
  1997年   7篇
  1996年   13篇
  1995年   5篇
  1994年   3篇
  1993年   6篇
  1992年   10篇
  1991年   13篇
  1990年   9篇
  1989年   8篇
  1987年   10篇
  1986年   10篇
  1985年   6篇
  1984年   4篇
  1983年   7篇
  1982年   2篇
  1981年   4篇
  1980年   4篇
  1979年   8篇
  1978年   4篇
  1977年   2篇
  1974年   6篇
  1972年   3篇
  1971年   4篇
  1956年   2篇
排序方式: 共有2668条查询结果,搜索用时 498 毫秒
31.
The association of celiac disease (CD) with cancers of gastrointestinal origin has been noted. However, coincidence of CD with nongastrointestinal neoplasms is an unusual event. Here we present five children with concurrent CD and nongastrointestinal neoplasms. All of the patients had positive serologic results for anti-tTG antibodies. Histological investigation of intestinal mucosa showed inflammation (Marsh score = 2) in all the patients. Two of these patients represented with germ cell malignancies. One patient had Wilms' tumor. To our knowledge, these are the first reports of coincidence of these two cancers with CD in children. From the remaining two patients, one was diagnosed with acute lymphoblastic leukemia, and the other with astrocytoma. The diagnosis of malignancy preceded CD diagnosis in all the patients (mean ages of cancer and CD diagnosis of 1.8 and 5.4 years old, respectively). Whether malignancy can promote immune deregulation and predispose to CD is uncertain. On the other hand, undiagnosed celiac may be a risk factor for cancer. Our results suggest a potential association of CD with malignancy nature of CD, however, occurrence of CD may be influenced by various intrinsic and extrinsic factors. There are few reports noting CD as a paraneoplastic condition. Further investigations are necessitated to stablish such relationship.  相似文献   
32.
BackgroundBarbed sutures provide a novel technique for knotless wound closure. They have mainly been used in plastic and general surgery. There are no reports about its use in the foot.MethodsWe present a case series of 11 feet in 8 patients whose wounds were closed with barbed sutures. Ten had primary hallux valgus correction and one had a revision correction.ResultsNo problems were noted at 2-weeks follow-up. Four of the 11 cases required open suture excision due to an adverse reaction. Five were followed to delayed wound healing. Histology results from one scar showed a localised histiocytic reaction and superficial dermal abscess formation.ConclusionsWe feel the thin subcutaneous tissue of the foot, the amount of motion and pressure from the shoe causes the barbs to repeatedly irritate the soft tissue. Based on our short case series we cannot recommend the use of a barbed skin closure system in the foot.  相似文献   
33.
BackgroundCurrent evidence suggests that dual-energy x-ray absorptiometry (DXA) scans, the conventional method defining osteoporosis, is underutilized and, when used, may underestimate patient risk for skeletal fragility. It has recently been suggested that other imaging modalities may better estimate bone quality, such as the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score which also may assess vertebral compression fracture risk in patients with spine metastases.PurposeTo evaluate whether VBQ score is predictive of fragility fractures in a population with pre-existing low bone density and at high-risk for fracture.Study Design/SettingRetrospective single-center cohort.Patient SamplePatients followed at a metabolic bone clinic for osteopenia and/or osteoporosis.Outcome MeasuresRadiographically-documented new-onset fragility fracture.MethodsPatients with a DXA and MRI scans at the time of consultation and ≥2-year follow-up were included. Details were gathered about patient demographics, health history, current medication use, and serological studies of kidney function and bone turnover. For each patient, VBQ score was calculated using T1-weighted lumbar MRI images. Univariable and multivariable analyses were used to identify the independent predictors of a new fragility fracture. To support the construct validity of VBQ, patient VBQ scores were compared to those in a cohort of 45 healthy adults.ResultsSeventy-two (39.1%) study participants suffered fragility fractures, the occurrence of which was associated with higher VBQ score (3.50 vs. 3.01; p<.001), chronic glucocorticoid use (30.6% vs. 15.2%; p=.014), and a history of prior fragility fracture (36.1% vs. 21.4%; p=.030). Mean VBQ score across all patients in the study cohort was significantly higher than the mean VBQ score in the healthy controls (p<.001). In multivariable analysis, new-onset fracture was independently associated with history of prior fracture (OR=6.94; 95% confidence interval [2.48–19.40]; p<.001), higher VBQ score (OR=2.40 per point; [1.30–4.44]; p=.003), higher body mass index (OR=1.09 per kg/m²; [1.01–1.17]; p=.03), and chronic glucocorticoid use (OR=2.89; [1.03–8.17]; p=0.043). Notably, DXA bone mineral density (BMD) was not found to be significantly predictive of new-onset fractures in the multivariable analysis (p=.081).ConclusionsHere we demonstrate the novel, MRI-derived VBQ score is both an independent predictor of fragility fracture in at-risk patients and a superior predictor of fracture risk than DXA-measured BMD. Given the frequency with which MRIs are obtained by patients undergoing spine surgery consultation, we believe the VBQ score could be a valuable tool for estimating bone quality in order to optimize the management of these patients.  相似文献   
34.
35.
Widespread microvascular injury followed by vessel obstruction may lead to disseminated intravascular coagulation (DIC). We describe a murine model wherein leukocytes interacting with inflamed microvessels in vivo are activated by antibodies. Treatment of tumor necrosis factor alpha (TNF-alpha)-primed mice with anti-Ly-6G antibodies reproduced many of the features of septic or traumatic shock including microvessel obstruction and coagulation, severe vasculitis, respiratory difficulties, and vascular leakage. Mice lacking either E-selectin or P-selectin were protected from this reaction as were animals treated with a combination of either selectin-blocking antibodies and heparin or a selectin antagonist plus heparin. Combined blockade of leukocyte/platelet adhesion and coagulation may provide convincing protection in DIC.  相似文献   
36.
AIM: Venous obstruction following transvenous device implantation rarely cause immediate clinical problems. When lead revision or device upgrade is indicated, venous obstruction become a significant challenge. The aim of this study was to determine the predictors of venous obstruction after transvenous device implantation, and to asess likely effects of antiplatelet/anticoagulant drugs in preventing venous thrombosis. METHODS AND RESULTS: Between March 2005 and July 2006, contrast venography was performed in 100 patients who were candidates for generator change, lead revision, or device upgrade. Vessel patency was graded as either completely obstructed, partially obstructed (>70%), or patent. The incidence of venous obstruction was 26%, with 9% of patients having total obstruction and 17% of patients exhibiting partial obstruction. No statistically significant differences between obstructed and non-obstructed patients were seen for age, sex, indication for device implantation, atrial fibrillation, cardiothoracic ratio, insulation material, operative technique, device type, and manufacturer (all Ps > 0.05). In a univariate analysis, multiple leads (P = 0.033), and presence of dilated cardiomyopathy (P = 0.036) were associated with higher risk of venous obstruction, whereas anticoagulant/antiplatelet therapy (P = 0.047) significantly reduced incidence of venous obstruction. Multivariate logistic regression analysis showed that only number of the leads (P = 0.039, OR: 2.22, and 95% CI: 1.03-4.76) and antiplatelet/anticoagulant therapy (P = 0.044, OR: 2.79, and 95% CI: 0.98-7.96) were predictors of venous obstruction. CONCLUSION: Total or partial obstruction of the access veins occurs relatively frequently after pacemaker or ICD implantation. Multiple pacing or ICD leads are associated with an increased risk of venous obstruction, whereas antiplatelet/anticoagulant therapy appears to have a preventive effect on development of access vein thrombosis.  相似文献   
37.
BACKGROUND: Approximately 30% of all accessory pathways (APs) are located in the septal area, and understanding the electrocardiographic and electrophysiologic of these APs is crucial for safe and effective ablation of these pathways. OBJECTIVE: In this study, the electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and posteroseptal APs were investigated in detail to elucidate unique electrical properties of APs in each location. METHODS: From April 2002 to October 2006, a total of 120 patients with a septal AP-mediated tachycardia were enrolled in the study. A detailed examination including electrocardiographic analysis and electrophysiologic study was performed in all patients. RESULTS: A total of 120 patients, including 98 patients with posteroseptal APs, 14 patients with anteroseptal APs, and 8 patients with midseptal APs, were studied. The anteroseptal APs could be differentiated from the midseptal APs by the 2 or more positive delta waves in inferior leads, whereas there is significant overlap in electrocardiographic features of midseptal and posteroseptal APs. The mean tachycardia cycle length was significantly shorter in patients with midseptal AP compared with those with anteroseptal and posteroseptal APs (284 +/- 49 ms vs 342 +/- 46 ms vs 350 +/- 68 ms, P = .03). The AH interval during tachycardia was also shorter in patients with midseptal APs (149 +/- 16 ms vs 200 +/- 51 ms vs 168 +/- 48 ms, P = .04). The patients with posteroseptal AP had a significantly higher incidence of atrial fibrillation (35%) than those with either midseptal (12%) or anteroseptal (14%) APs (P = .04). The patients with posteroseptal APs also had a significantly shorter antegrade effective refractory period of the AP (276 +/- 54 ms) than those with either midseptal (313 +/- 71 ms) or anteroseptal (325 +/- 61) APs (P = .036). CONCLUSION: Electrocardiographic analysis is a reliable method for differentiation of the anteroseptal from the midseptal APs, whereas the same is not true for the midseptal and posteroseptal APs. Midseptal APs were characterized by faster orthodromic tachycardia, whereas posteroseptal APs had a higher inducibility of atrial fibrillation.  相似文献   
38.
Haque MZ  Majid DS 《Hypertension》2004,43(2):335-340
To determine the role of endogenous superoxide (O2-) in the kidney, we assessed renal hemodynamics and excretory function in gp91(PHOX) (a NAD(P)H oxidase subunit) gene knockout (KO) mice and compared these findings with those of wild-type (WT) strain C57BL/6 mice. Renal blood flow (RBF) and glomerular filtration rate (GFR) were determined by PAH and inulin clearances respectively in anesthetized mice (n=8 in each group). There were higher baseline RBF (4.3+/-0.4 versus 2.5+/-0.2 mL/min per gram; P<0.002) and lower renal vascular resistance (RVR) (16+/-1.4 versus 29+/-2.3 mm Hg/mL/min per gram; P<0.0001) in KO compared with WT without a significant difference in mean arterial pressure (MAP) (67+/-2 versus 71+/-2 mm Hg) and GFR (0.66+/-0.09 versus 0.73+/-0.05 mL/min per gram) between the strains. Intravenous infusion of angiotensin II (Ang II) (2 ng/min per gram of body weight) for 30 minutes caused a lesser degree of decreases in RBF (-8% versus -33%) and of increases in RVR (+73% versus +173%) in KO compared with WT. GFR was increased (43%) in KO but not in WT during Ang II infusion. Urinary excretion of nitrate/nitrite was higher in conscious KO (n=5) than in WT (n=5), indicating an increase in nitric oxide bioavailability that could be the cause of high RBF and low RVR in KO. These data indicate that gp91(PHOX), a subunit of NAD(P)H oxidase, plays a regulatory role in the maintenance of renal vascular tone. These results also suggest that the mechanism of Ang II-mediated renal vascular action involves concomitant generation of O2-.  相似文献   
39.
Objective We conducted this study to compare the rate of ≥1 inappropriate therapy between ICDs from two manufacturers which use different discriminatory protocols. Method One hundred sixty two patients (mean age 58 ± 13 years, 126 male) who received ICDs between January 2001 and 2005 were included in the study. Clinical, electrocardiographic, and ICD stored data and electrograms were collected and analyzed. Immediately after implantation all the detection and discrimination criteria were activated with the nominal values in order to compare the two discriminatory protocols under the default manufacturer’s settings. Results During the follow up period of 14.3 ± 10 months, 49 (30%) patients received ≥1 inappropriate ICD therapy. The rate of ≥1 inappropriate ICD therapy in manufacturer A and B ICDs was 26% (n = 29) and 41% (n = 20), respectively. Comparing the rate of ≥1 inappropriate ICD therapy between the two groups by Kaplan–Meier analysis and the log rank test resulted in P = 0.04. Conclusion Having all discriminatory variables activated with the nominal values, discriminatory performance differs between the two manufacturers. Further larger-scale studies are warranted to prospectively compare the performance of various available ICDs’ discriminatory protocols, and define the optimum combination of discriminators in each ICD to decrease the rate of inappropriate therapy.  相似文献   
40.
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