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   21470篇
  免费   1903篇
  国内免费   1477篇
耳鼻咽喉   125篇
儿科学   217篇
妇产科学   196篇
基础医学   2656篇
口腔科学   372篇
临床医学   3040篇
内科学   3116篇
皮肤病学   221篇
神经病学   1129篇
特种医学   729篇
外国民族医学   13篇
外科学   2089篇
综合类   3965篇
现状与发展   5篇
预防医学   1097篇
眼科学   563篇
药学   2303篇
  21篇
中国医学   1185篇
肿瘤学   1808篇
  2024年   78篇
  2023年   411篇
  2022年   967篇
  2021年   1164篇
  2020年   897篇
  2019年   710篇
  2018年   810篇
  2017年   690篇
  2016年   698篇
  2015年   1058篇
  2014年   1276篇
  2013年   1076篇
  2012年   1607篇
  2011年   1766篇
  2010年   1031篇
  2009年   803篇
  2008年   1073篇
  2007年   1038篇
  2006年   1085篇
  2005年   1052篇
  2004年   696篇
  2003年   629篇
  2002年   545篇
  2001年   482篇
  2000年   503篇
  1999年   512篇
  1998年   305篇
  1997年   301篇
  1996年   209篇
  1995年   205篇
  1994年   218篇
  1993年   116篇
  1992年   128篇
  1991年   125篇
  1990年   124篇
  1989年   89篇
  1988年   86篇
  1987年   77篇
  1986年   61篇
  1985年   57篇
  1984年   21篇
  1983年   12篇
  1982年   15篇
  1981年   14篇
  1980年   3篇
  1979年   15篇
  1978年   2篇
  1977年   2篇
  1976年   3篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
目的 掌握中国就业流动人口红肉摄入水平和超标率。方法 采用分层整群抽样方法,利用半定量食物频率表膳食调查法分析中国31个省(自治区、直辖市)和新疆生产建设兵团170个县(区、团)中48 511名18~59岁就业流动人口的红肉摄入情况。对数据进行复杂加权后,计算不同人口学特征的流动人口日均红肉摄入量和超标率。结果 (1)样本人群日均红肉摄入量为125.9(95%CI:116.5~132.5)g,男性高于女性,分别为141.6(95%CI:131.3~148.9)g和104.7(95%CI:95.8~111.2)g,差异有统计学意义(P<0.01)。未发现红肉摄入量随年龄、文化程度、BMI的变化趋势(趋势检验P值均>0.05)。按照2010年人口普查数据标化后,标化日均红肉摄入量为121.0(95%CI:113.4~128.7)g。(2)样本人群日均红肉摄入超标率为36.2%(95%CI:33.0%~39.3%),男性远高于女性,分别为42.4%(95%CI:38.9%~45.8%)和27.8%(95%CI:27.1%~31.0%),差异有统计学意义(P<0.01)。男女性别人群均为30~39岁组超标率最高,分别为43.5%(95%CI:39.7%~47.4%)和30.1%(95%CI:26.5%~33.9%)。标化日均红肉摄入超标率为34.6%(95%CI:31.9%~38.0%)。结论 中国就业流动人口日均红肉摄入量超过世界癌症基金会推荐的标准,摄入量和摄入超标率均高于当地常住人口。  相似文献   
992.
The live attenuated Japanese encephalitis (JE) vaccine SA14-14-2 was licensed decades ago and now approved for clinical use in most JE endemic countries. Large-scale clinical trials demonstrate ideal safety and efficacy profile of this Chinese vaccine. The SA14-14-2 vaccine was derived from a virulent strain SA14 after hundreds of serial passaging in cells and animals, concern about virulence reversion remains exist. In the present study, to study the in vitro and in vivo genetic and attenuation stability of the vaccine virus, SA14-14-2 was serially passaged in Vero cells and mouse brain followed by sequence comparison and attenuation phenotype analysis. The results showed that no significant mutation was acquired after serial passaging in Vero cells except a single Ser66Leu mutation within capsid protein, which had no effect on viral virulence in mice. Importantly, serial passaging of SA14-14-2 in suckling mouse brain resulted in emergence of adaptive mutations and increased virulence in mice. Population and plaque-purified clone consensus sequence analysis showed four adaptive mutations in envelope (E) protein, F107L, K138E, T226R and I270T, sequentially occurred and become predominant during serial passaging in suckling mouse brain. Especially, these adaptive mutations were close related with the enhanced neurovirulence and neuroinvasiveness in mice. Our results provide experimental evidence of highly genetic and attenuation stability of SA14-14-2 following passaging in Vero cells, and reveal the potential virulence reversion during passaging in mouse brain in association with critical adaptive mutations in E protein. These findings are important for quality control and evaluation of live JE vaccines and will help understand the attenuation mechanism of flavivirus vaccine.  相似文献   
993.
目的 探讨全覆膜金属支架在治疗无法行外科手术的胰腺导管内乳头状黏液性肿瘤(IPMN)患者中的应用价值。方法 回顾性分析2015年12月-2020年6月在江苏省苏北人民医院内镜诊治中心行内镜逆行胰胆管造影术(ERCP),在胰管留置全覆膜金属支架的9例IPMN患者的临床资料。结果 9例患者均行ERCP,术中见乳头呈鱼嘴样开口,插管后均可见胶冻状液体流出,造影见主胰管局部或弥漫扩张,分枝胰管呈囊状扩张,5例置入10 mm×80 mm、4例置入10 mm×60 mm全覆膜金属支架,2例术中同时置入胆道支架。术后患者腹痛和恶心呕吐等症状明显缓解,2例术后出现高淀粉酶血症,给予对症治疗后缓解,无胰腺炎、胆管炎、出血和穿孔等并发症发生。术后随访12~24个月,无腹痛和复发,无支架移位,合并糖尿病患者血糖控制稳定,无新发糖尿病,1例随访至16个月时,支架堵塞,行胰管清理及支架更换。出院当天生活质量卡氏评分为(96.67±3.54)分,较术前的(82.78±3.63)分明显提高,两者比较,差异有统计学意义(P <0.05),术后3和6个月生活质量卡氏评分为(94.82±3.87)和(91.33±2...  相似文献   
994.
目的 探讨关节镜清理联合富血小板血浆(PRP)治疗冈上肌钙化性肌腱炎的临床效果。方法选取该院采用关节镜清理与PRP治疗冈上肌钙化性肌腱炎的患者46例,分为实验组和对照组,各23例。实验组行肩关节镜下钙化灶清理+PRP注射,对照组行单纯关节镜清理,比较两组的治疗效果。结果 所有患者均得到有效随访。实验组中,5例行肩袖修补术(3例为术前确诊肩袖撕裂,2例为钙化灶较大,清理后行肩袖修补),对照组中,3例行肩袖修补术(2例为术前确诊肩袖撕裂,1例为钙化灶较大,清理后行肩袖修补)。两组患者术后1个月视觉模拟评分法(VAS)明显低于术前,美国肩肘外科协会(ASES)评分明显高于术前,差异均有统计学意义(P <0.05)。实验组术后1个月VAS明显低于对照组,术后1个月ASES评分明显高于对照组,差异均有统计学意义(t=-5.52,t=8.73,P=0.001)。结论 关节镜清理联合PRP治疗冈上肌钙化性肌腱炎,是一种有效、微创的方法。关节镜可以尽量清除钙盐,能对肩袖损伤范围精确评估,并对明确的、损伤较大的肩袖损伤,行带线锚钉肩袖修补。同时,结合PRP注射,可加快损伤肩袖的修复,减轻疼痛,加速...  相似文献   
995.
996.

Background

As a vascular malformation, venous angioma in the spinal cord is extremely rare. To our knowledge, there are only five case reports in the literature, and it has not been previously reported in the pediatric age group.

Case report

In this paper, we report on a 3-year-old patient who presented with progressive weakness in his left upper limb. Spinal magnetic resonance imaging (MRI) revealed an epidural cystic mass at the C6–T2 level. The lesion was diagnosed as venous angioma after total removal with laminectomy. Postoperatively, the patient remained symptom free, and no tumor recurrence was confirmed based on MRI at the time of the 18-month follow-up. The clinical, radiological, surgical, and pathological features of this abnormality are discussed, and all six reported cases were reviewed.

Conclusion

Venous angiomas should be included in the differential diagnosis of spinal cystic lesions in children. A definitive diagnosis is difficult based on MRI alone. This rare lesion is amenable to surgery, and gross total removal (GTR) is usually achievable due to a well-demarcated dissection plane. A good clinical outcome after GTR can be expected.  相似文献   
997.
老年惊厥性癫痫持续状态28例临床分析   总被引:1,自引:0,他引:1  
目的观察老年惊厥性癫痫持续状态(CSE)的临床特点。方法收集神经重症监护室(NICU)年龄≥60岁的CSE患者28例,回顾性分析其临床特点。结果脑血管病为28例老年CSE的首位病因。接受抗癫痫药物治疗后,CSE症状控制的中位时间为0.9 h,其中16例患者在1 h内症状控制,12例为难治性癫痫持续状态(RSE)。28例患者中,存活16例、死亡12例。死亡者与存活者相比,合并中枢神经系统新发疾病(P=0.027)和RSE的比例显著不同(P=0.027)。结论老年CSE患者基础情况差,病因多样,合并有中枢神经系统新发疾病或有RSE者的死亡率高。  相似文献   
998.
目的 提高肿瘤化疗患儿外周静脉输液的质量和安全性.方法 将62例淋巴细胞性白血病化疗患儿按入院时间顺序分为对照组26例,观察组36例;对照组行常规护理及管理;观察组由化疗安全护理小组进行评估、操作、维护等全程护理管理.结果 观察组患儿静脉炎及液体渗漏发生率显著低于对照组,满意率显著高于对照组(P<0.05,P<0.01),输液静脉穿刺一次成功率相对高于对照组(分别为94.4%、76.9%).结论 构建和实施专门管理机制,有利于提高化疗患儿静脉输液质量,保障护理安全.  相似文献   
999.

Background

How to identify whether T1–2 colorectal cancers have lymph nodes metastases pre-op or intra-op is a crucial problem in clinic. The purpose of this study was to evaluate the feasibility of using carbon nanoparticles to track lymph nodes metastases in T1–2 colorectal cancers.

Methods

A multi-center study was performed between July 2012 and January 2014. Seventy-three patients with T1–2 colorectal cancer identified by pre-op endoscopic ultrasonography (EUS) were recruited. 1 ml carbon nanoparticles suspension was endoscopically injected into the submucosal layer at four points around the site of the primary tumor 1 day before surgery. Laparoscopic radical resection with lymphadenectomy was performed. Sentinel lymph nodes (SLNs) were defined as nodes that were black-dyed by carbon nanoparticles. Pathology confirmed whether lymph nodes have cancer metastases and the SLNs accuracy.

Results

SLNs were easily found under laparoscopy. The mean number of SLNs was 3 (range 1–5). All patients had SLNs lying alongside the mesenteric vessel or main arterial vessel. After pathological analysis, 2 patients (9.52 %) had lymph node metastasis in 21 patients with EUS T1 cancers, and 10 patients (19.23 %) had lymph node metastasis in 52 patients with EUS T2 cancers. In two T1 cases with lymph node metastasis, SLNs were positive with 100 % accuracy. In ten T2 cases with lymph node metastasis, SLNs were positive in nine cases. In pathology, carbon nanoparticles were seen in lymphatic vessels, and lymphoid sinus and macrophages in negative SLNs. When SLNs were positive, carbon nanoparticles were seen around cancer cells in lymph nodes. The overall sensitivity, specificity, accuracy of SLNs in T1–2 colorectal cancers were 91.67, 100, 98.63 %, respectively.

Conclusions

We demonstrated the feasibility of using carbon nanoparticles to track lymph nodes metastases in T1–2 colorectal cancers. Carbon nanoparticles black-dyed lymph nodes play a role as SLNs in T1–2 colorectal cancers.  相似文献   
1000.
Most patient satisfaction studies put an emphasis on finding key drivers (attribute) to increase overall patient satisfaction. However, it is not clear how much health care managers need to improve certain attributes to attain the target overall patient satisfaction level. The study aims at finding not only what attributes, but also how much these attributes need to be improved to attain the target levels of patient satisfaction. The study uses an ordinal logistic regression model to analyze attribute reactions to salient drivers. This approach would significantly enhance health care managers' capabilities to develop a strategic plan to improve their patient satisfaction levels.  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