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   22984篇
  免费   1846篇
  国内免费   706篇
耳鼻咽喉   89篇
儿科学   582篇
妇产科学   632篇
基础医学   1158篇
口腔科学   411篇
临床医学   3173篇
内科学   5234篇
皮肤病学   103篇
神经病学   720篇
特种医学   885篇
外国民族医学   7篇
外科学   2978篇
综合类   3565篇
现状与发展   1篇
预防医学   1402篇
眼科学   52篇
药学   2447篇
  40篇
中国医学   1091篇
肿瘤学   966篇
  2024年   26篇
  2023年   485篇
  2022年   633篇
  2021年   1147篇
  2020年   1028篇
  2019年   946篇
  2018年   863篇
  2017年   892篇
  2016年   939篇
  2015年   907篇
  2014年   1726篇
  2013年   1859篇
  2012年   1467篇
  2011年   1548篇
  2010年   1270篇
  2009年   1124篇
  2008年   1033篇
  2007年   1052篇
  2006年   980篇
  2005年   818篇
  2004年   648篇
  2003年   563篇
  2002年   480篇
  2001年   404篇
  2000年   356篇
  1999年   268篇
  1998年   219篇
  1997年   190篇
  1996年   197篇
  1995年   183篇
  1994年   165篇
  1993年   122篇
  1992年   139篇
  1991年   108篇
  1990年   103篇
  1989年   93篇
  1988年   78篇
  1987年   62篇
  1986年   48篇
  1985年   62篇
  1984年   46篇
  1983年   38篇
  1982年   40篇
  1981年   36篇
  1980年   33篇
  1979年   20篇
  1978年   26篇
  1977年   18篇
  1976年   15篇
  1975年   8篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
1.
目的:探讨早产儿消化道穿孔的病因,分析影响早产儿消化道穿孔短期预后不良的危险因素。方法:回顾性分析山西省 儿童医院新生儿外科2015年1月—2021 年5月诊治的89 例早产儿消化道穿孔的临床资料。根据术后3 个月时结局分为生存 组和预后不良组。比较两组术前、术中及术后与早产儿消化道穿孔预后不良相关的因素,采用Logistic 回归分析筛选早产儿消 化道穿孔预后不良的危险因素。结果:早产儿消化道穿孔的病死率为25.84%,坏死性小肠结肠炎(NEC)和胃壁肌层缺损是早产 儿消化道穿孔常见的病因。单因素分析显示生存组患儿从发现气腹至手术时间在8 h 之内的比例显著高于预后不良组 (χ2=15.22,P<0.01)。预后不良组合并脓毒性休克的比例显著高于生存组(χ2=33.19,P<0.01)。预后不良组术后合并需非计划二次 手术的并发症比例显著高于生存组(χ2=7.24,P<0.01)。Logistic 回归分析显示脓毒性休克(OR=0.06,95%CI:0.02~0.21,P<0.01)和 气腹至手术时间大于8 h(OR=0.23,95%CI:0.07~0.81,P<0.05)是早产儿消化道穿孔短期预后不良的危险因素。结论:NEC 和胃 壁肌层缺损是早产儿消化道穿孔的主要病因,脓毒性休克和从气腹发生至手术时间大于8 h 是早产儿消化道穿孔短期预后 不良的危险因素。  相似文献   
2.
BackgroundGastrointestinal stromal tumors have been detected in 25% of the necropsies performed on NF1 patients, but have been reported only in 7% of NF1 patients in the largest series. Such data imply an important gap between the true presence of tumors and those diagnosed. Few genotype-phenotype relationships have been described but to date none referring to abdominal tumors.ObjectivesEvaluate retrospectively the efficacy of a regular and proactive follow-up of NF1 patients to early diagnose abdominal tumors and report their mutations.MethodsCohort study performed between 2010 and 2020, with 43 NF1 adult patients followed at our Dermatology department.ResultsEight abdominal tumors were diagnosed in six patients, meaning that 14% of the followed patients developed an abdominal tumor. Five patients (83%) were asymptomatic. Five (83.3%) had a family history of NF1 with abdominal tumors (patients 1,2 and 3,4,5 were relatives).ConclusionsAlthough currently gastrointestinal routine screening investigations for asymptomatic patients are not recommended in the guidelines, the family aggregation in our series suggests it should be considered a close follow-up of the relatives of a patient with an NF1-related abdominal tumor. Also, for the first time, two mutations [c.2041C > T (p.Arg681Ter) and c.4537C > T (p.Arg1513*)] have been associated with family aggregation of abdominal tumors in NF1 patients.  相似文献   
3.
IntroductionVascularized fibular autografts (VFA) are used in the oncologic skeletal reconstructions of long bones, alone or combined with massive bone allografts (MBA). Data regarding the role of imaging in assessing these complex skeletal reconstructions are lacking, and have mainly focused on Computed Tomography (CT). Our aim was to evaluate if early conventional radiography (CR) findings are correlated with the outcome of these skeletal reconstructions.Materials and methodsAll consecutive patients who underwent oncologic resection of lower limbs long bones followed by VFA reconstruction were included in this single-center retrospective study. We compared the CR obtained immediately after surgery with the CR at the 6-month control, as well as the CR at 6 months with the CT at 6 months when available. The following scores were assigned to the VFA: 0 (unchanged), 1 (osteopenia-cortical bone thinning), 2 (increase in bone density-cortical thickening). We then investigated whether this score correlated with the implant outcome within 12 months (optimal integration, suboptimal integration, integration requiring further surgery or lack of integration) using Kaplan-Meier and Cox regression analyses, considering the occurrence of integration and the duration time before the surgical removal of the whole bone reconstruction.ResultsForty-five patients were included (32 men [71.1%], mean age 14.6 years), 26 affected by osteosarcoma, 14 by Ewing sarcoma, 3 by adamantinoma and 2 operated for the failure of previous reconstructions for bone sarcoma. VFA changes on 6-month CR were significantly associated with optimal integration of the implants (log-rank P = 0.0137, multivariate Hazard ratio = 7.62, 95% confidence interval = 1.13–51.25). None of the other clinical and surgical features were associated with the implant outcome. The findings on 6-month CR and CT follow-up were not significantly different. CT at 6 months was available in 36 patients (80.0%).ConclusionThe assessment of VFA morphological changes on CR performed at 6 months can predict the outcome of the skeletal implant. This data should be considered for clinical decision-making, selecting patients requiring additional images (CT), and possible subsequent revision surgical procedures.  相似文献   
4.
IntroductionThe Modena bleeding score is a categorical rating scale that allows the assessment of the surgical field in relation to bleeding during endoscopic surgery. It has recently been presented and validated in the field of endoscopic ear surgery by the present authors. The Modena bleeding score provides five grades for rating the surgical field during endoscopic procedures (from grade 1 ? no bleeding to grade 5 ? bleeding that prevents every surgical procedure except those dedicated to bleeding control).ObjectiveThe aim of this study was to validate the Modena bleeding score in the setting of endoscopic sinus surgery.MethodsFifteen three-minute videos of endoscopic sinus surgery procedures (each containing three bleeding situations) were evaluated by 15 specialists, using the Modena bleeding score. Intra and inter-rater reliability were assessed, and the clinical validity of the Modena bleeding score was calculated using a referent standard.ResultsThe data analysis showed an intra-rater reliability ranging from 0.6336 to 0.861. The inter-rater reliability ranged from 0.676 to 0.844. The clinical validity was α = 0.70; confidence limits: 0.64 ? 0.75, corresponding to substantial agreement.ConclusionThe Modena bleeding score is an effective method to score bleeding during endoscopic sinus surgery. Its application in future research could facilitate the performance and efficacy assessment of surgical techniques, materials or devices aimed to bleeding control during endoscopic sinus surgery.  相似文献   
5.
PurposeThe aim of this study was to compare catheter angiography (CA) and colonoscopy outcomes after successful CT angiographic (CTA) localization for patients with overt lower gastrointestinal bleeding (LGIB).MethodsSeventy-one consecutive patients from two institutions between 2010 and 2020 had both contrast extravasation on CTA imaging in the lower gastrointestinal tract and subsequent CA or colonoscopy. The primary outcome was confirmation of active bleeding during CA or colonoscopy (defined as confirmation yield). The secondary outcomes were to determine therapeutic yield (hemostatic therapy), time to procedure, rebleeding rate, and adverse outcome rates (defined as surgery, acute kidney injury, initiation of dialysis, and overall mortality). Univariate analyses and multivariable analyses with P < .05 were used to determine statistical significance.ResultsForty-four patients underwent CA and 27 underwent colonoscopy. CA had higher overall confirmation yield (55% vs 26%, P = .026), whereas therapeutic yields were similar (70% vs 56%, P = .214). Time to procedure was 5.1 ± 3.4 hours for CA and 15.5 ± 13.6 hours for colonoscopy (P < .001). On multivariable analysis, shorter time to procedure was the only statistically significant predictor of confirmation yield (P = .037) and therapeutic yield (P = .013), whereas procedure, hemoglobin, transfusions, and hemodynamic instability were not. Adverse events and rebleeding were not statistically different between patients who underwent CA and colonoscopy (P > .05).ConclusionsShorter time to procedure was the only statistically significant predictor of confirmation and therapeutic yield after CTA localization of LGIB. Because CA can be performed sooner than colonoscopy without increased rates of adverse outcomes or rebleeding, CA may be a reasonable first-line treatment option in patients with CTA localization of LGIB.  相似文献   
6.
目的探讨维持性血液透析(MHD)患者血清维生素D水平对下肢肌力减退的预测作用。 方法横断面研究设计,选择2018年9月至10月于战略支援部队特色医学中心血液净化中心的95例MHD患者,检测其血清25-羟维生素D3[25(OH)D3]水平,采用5次站立-坐下实验(5-STS)评价其下肢肌力。根据5-STS完成时间将MHD患者分为下肢肌力正常组(n=85)与减退组(n=10),比较两组患者人口学特征、实验室指标。采用多因素Logistic回归分析下肢肌力减退的影响因素,绘制受试者工作特征(ROC)曲线分析上述因素预测MHD患者发生下肢肌力减退的特异度和敏感度。 结果95例MHD患者血清25(OH)D3水平为11.00~99.50 nmol/L,中位数31.23(19.90~43.30)nmol/L;5-STS完成时间为3.55 s~18.71 s,中位数9.81(7.12,12.43)s,下肢肌力减退者10例(10.53%)。多因素Logistic回归分析显示,血清25(OH)D3是MHD患者下肢肌力减退的保护性因素[OR=0.761,95%CI(0.592~0.978),P=0.033]。进一步ROC曲线分析显示,25(OH)D3对应的ROC曲线下面积为0.815,其预测MHD患者发生下肢肌力减退的敏感度为80.00%,特异度为80.00%。 结论MHD患者血清25(OH)D3水平普遍较低,下肢肌力减退者更为明显;血清维生素D水平对MHD患者是否存在下肢肌力减退具有较好的预测价值。  相似文献   
7.
We report a rare case of uterine carcinosarcoma involving a 74-year-old woman. The patient complained of posmenopausal bleeding. The disease was eventually diagnosed as simultaneous uterine carcinosarcoma and high-grade serous tubal carcinoma.Clinical examination found a cervical tumour and transvaginal ultrasound showed a heterogeneous intrauterine image. The histological result of both findings was carcinosarcoma.The computed tomography scan and magnetic resonance imaging reported similar findings for intrauterine and cervical tumour, with the same features as a possible myoma or mass with sarcomatous degeneration.Given the suspicion of a high-risk variant of endometrial adenocarcinoma, the primary management of carcinosarcoma is surgery. Complete surgical staging included total hysterectomy, bilateral salpingo-oophorectomy, omentectomy, pelvic and para-aortic lymph node dissection.The pathological findings revealed a uterine carcinosarcoma tumour, invading less than half the myometrium and the stromal connective tissue of the cervix but not extending beyond the uterus. The histopathological studies of bilateral adnexectomy and the peritoneal biopsy demonstrated the presence of high-grade serous tubal carcinoma. The lymph study was negative for malignancy.We concluded a synchronous diagnosis of uterine carcinosarcoma stage II and high-grade serous tubal carcinoma stage IIIB.A detailed literature search and management of this entity are discussed.  相似文献   
8.
9.
First-line chemotherapy for advanced/metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric/gastroesophageal junction cancer (GC/GEJC) has poor median overall survival (OS; <1 year). We report efficacy and safety results from Chinese patients in the phase III global CheckMate 649 study of nivolumab plus chemotherapy vs chemotherapy for the first-line treatment of GC/GEJC/esophageal adenocarcinoma (EAC). Chinese patients with previously untreated advanced or metastatic GC/GEJC/EAC were randomized to receive nivolumab (360 mg Q3W or 240 mg Q2W) plus chemotherapy (XELOX [capecitabine and oxaliplatin] Q3W or FOLFOX [oxaliplatin, leucovorin and 5-fluorouracil] Q2W), nivolumab plus ipilimumab (not reported) or chemotherapy alone. OS, blinded independent central review-assessed progression-free survival (PFS), objective response rate (ORR), duration of response (DOR) and safety are reported. Of 1581 patients enrolled and randomized, 208 were Chinese. In these patients, nivolumab plus chemotherapy resulted in clinically meaningful improvement in median OS (14.3 vs 10.2 months; HR 0.61 [95% CI: 0.44-0.85]), median PFS (8.3 vs 5.6 months; HR 0.57 [95% CI: 0.40-0.80]), ORR (66% vs 45%) and median DOR (12.2 vs 5.6 months) vs chemotherapy, respectively. The safety profile was acceptable, with no new safety signals observed. Consistent with results from the global primary analysis of CheckMate 649, nivolumab plus chemotherapy demonstrated a clinically meaningful improvement in OS and PFS and higher response rate vs chemotherapy and an acceptable safety profile in Chinese patients. Nivolumab plus chemotherapy represents a new standard first-line treatment for Chinese patients with non-HER2-positive advanced GC/GEJC/EAC.  相似文献   
10.
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