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   199163篇
  免费   19652篇
  国内免费   13165篇
耳鼻咽喉   1921篇
儿科学   2147篇
妇产科学   2596篇
基础医学   23586篇
口腔科学   3652篇
临床医学   25578篇
内科学   27592篇
皮肤病学   2407篇
神经病学   10265篇
特种医学   7163篇
外国民族医学   100篇
外科学   20203篇
综合类   34704篇
现状与发展   43篇
一般理论   23篇
预防医学   13681篇
眼科学   5048篇
药学   21966篇
  215篇
中国医学   12696篇
肿瘤学   16394篇
  2024年   498篇
  2023年   2947篇
  2022年   5132篇
  2021年   10339篇
  2020年   8122篇
  2019年   6889篇
  2018年   7239篇
  2017年   6797篇
  2016年   6213篇
  2015年   9680篇
  2014年   11770篇
  2013年   11064篇
  2012年   16014篇
  2011年   17246篇
  2010年   11355篇
  2009年   8730篇
  2008年   11331篇
  2007年   10789篇
  2006年   10221篇
  2005年   9878篇
  2004年   6523篇
  2003年   6061篇
  2002年   5164篇
  2001年   4328篇
  2000年   4250篇
  1999年   4229篇
  1998年   2465篇
  1997年   2512篇
  1996年   1934篇
  1995年   1871篇
  1994年   1633篇
  1993年   960篇
  1992年   1342篇
  1991年   1178篇
  1990年   940篇
  1989年   875篇
  1988年   793篇
  1987年   631篇
  1986年   480篇
  1985年   414篇
  1984年   193篇
  1983年   165篇
  1982年   98篇
  1981年   126篇
  1980年   81篇
  1979年   108篇
  1978年   52篇
  1977年   51篇
  1976年   42篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
聚酰胺—胺树枝状聚合物(PAMAM)作为一种新型超支化大分子聚合物,因其出色的化学和生物学特性,一直被众学者称之为“人工蛋白”。 PAMAM的特点是存在内部空腔,并含有大量的反应性末端基团,这些结构使得PAMAM可以被用作仿生大分子,模拟天然有机基质在牙体组织表面进行仿生矿化,即PAMAM作为有机模板调控矿物质成核以及晶体的生长,以此来建造比传统的异体材料更加理想的牙体修复材料。本文就 PAMAM 诱导牙体硬组织仿生矿化的研究进展作一综述。  相似文献   
82.
BACKGROUND Helicobacter pylori(H.pylori)infection is known to prevent the occurrence of gastroesophageal reflux disease(GERD)by inducing gastric mucosal atrophy.However,little is known about the relationship between atrophic gastritis(AG)and GERD.AIM To confirm the inverse correlation between AG and the occurrence and severity of GERD.METHODS Individuals receiving health checkups who underwent upper gastrointestinal endoscopy at Seoul National University Healthcare System Gangnam Center were included.The grade of reflux esophagitis was evaluated according to the Los Angeles classification.Endoscopic AG(EAG)was categorized into six grades.Serologic AG(SAG)was defined as pepsinogen I≤70 ng/m L and pepsinogen I/II ratio≤3.0.The association between the extent of EAG and SAG and the occurrence and severity of GERD was evaluated using multivariate logistic regression analysis.RESULTS In total,4684 individuals with GERD were compared with 21901 healthy controls.In multivariate logistic regression analysis,advanced age,male sex,body mass index>23 kg/m2,presence of metabolic syndrome,current smoking,and alcohol consumption were associated with an increased risk of GERD.Seropositivity for H.pylori immunoglobulin G antibodies was associated with a decreased risk of GERD.There was an inverse correlation between the extent of EAG and occurrence of GERD:Odds ratio(OR),1.01[95%confidence interval(CI):0.90-1.14]in C1,0.87(0.78-0.97)in C2,0.71(0.62-0.80)in C3,0.52(0.44-0.61)in O1,0.37(0.29-0.48)in O2,and 0.28(0.18-0.43)in O3.Additionally,the extent of EAG showed an inverse correlation with the severity of GERD.The presence of SAG was correlated with a reduced risk of GERD(OR=0.49,95%CI:0.28-0.87,P=0.014).CONCLUSION The extent of EAG and SAG exhibited strong inverse relationships with the occurrence and severity of GERD.AG followed by H.pylori infection may be independently protect against GERD.  相似文献   
83.
Background:Gastrointestinal complications and malnutrition are common problems that affect postoperative rehabilitation and survival of patients with esophageal cancer. Evidence has shown that probiotics have a positive effect on improving gastrointestinal complications and nutritional status of patients with esophageal cancer after surgery, but there is a lack of prospective studies on this topic. We designed this prospective randomized controlled trial to evaluate the effects of probiotics on gastrointestinal complications and nutritional status in patients with postoperative esophageal cancer.Methods:This is a prospective, randomized, double-blind, placebo-controlled trial. It was approved by the Clinical Research Ethics Committee of our hospital. 192 patients will be randomly divided into probiotics group and the placebo group in a 1:1 ratio. After operation, probiotics and placebo will be given orally for 8 weeks. The indexes of nutritional status and incidence of digestive tract complications will be recorded and the data will be analyzed by SPSS 18.0 software.Discussion:This study will evaluate the effect of probiotics on gastrointestinal complications and nutritional status of postoperative patients with esophageal cancer. The results of this study will provide clinical basis for the use of probiotics in postoperative treatment of esophageal cancer.Trial registration:OSF Registration number: D DOI 10.17605/OSF.IO/QHW86  相似文献   
84.
Introduction: Malnutrition increases the risk of cancer treatment-related complications. Nutritional intervention is beneficial for the outcomes of outpatients with cancer. This study investigated the impacts of nutrition consultation and care on energy intake and weight change in inpatients receiving cancer treatment.

Methods: We conducted a longitudinal study, enrolling 3221 inpatients with head and neck, lung, hepatobiliary, upper gastrointestinal, colorectal, breast, or gynecological cancer who received at least two nutrition consultations between April 2010 and July 2015. In every consultation, a dietitian calculated the total energy requirement and the actual energy intake was assessed using a 24-h dietary recall.

Results: Patients with head and neck cancer lost the most weight (1.16?kg/mo). For every consultation, a 0.03-kg weight gain per month was observed (P?=?0.001). The average energy consumption percentage (% estimated energy requirement) at the third consultation was 87.0%. After controlling for potential covariates, the energy consumption percentages at the third, fourth, fifth–seventh, eighth, and subsequent consultations were significantly higher than those at the first consultation (P?<?0.05).

Conclusion: For oncology inpatients, routine screening and at least three active nutrition consultations with dietitians effectively improved energy intake and preserved body weight.  相似文献   

85.
舌癌患者手术及放化疗后会出现构音障碍、吞咽困难、口腔黏膜炎、口干、营养不良等并发症,使患者生存质量下降,甚至导致肿瘤的复发转移,影响生存期,单一方法往往顾此失彼。依托于中国中医科学院西苑医院肿瘤康复基地,杨宇飞教授在国内外调研考察基础上,结合中国国情,构建了一种“门诊多学科肿瘤康复模式”,在舌癌康复方面,以患者为中心,以中医肿瘤内科为主导,多学科共同参与,结合康复科、口腔科、营养科、药剂科等各科优势,形成全程个体化规范序贯康复方案,对患者及早进行康复,在放疗前进行预防性干预尤其重要,使患者能够快速缓解手术和放疗的不良反应,患者获益明显。现取两个典型案例总结其舌癌多学科康复的经验,以期为舌癌的康复提供借鉴。  相似文献   
86.
87.
88.
The analysis of quality of life (QoL) data can be challenging due to the skewness of responses and the presence of missing data. In this paper, we propose a new weighted quantile regression method for estimating the conditional quantiles of QoL data with responses missing at random. The proposed method makes use of the correlation information within the same subject from an auxiliary mean regression model to enhance the estimation efficiency and takes into account of missing data mechanism. The asymptotic properties of the proposed estimator have been studied and simulations are also conducted to evaluate the performance of the proposed estimator. The proposed method has also been applied to the analysis of the QoL data from a clinical trial on early breast cancer, which motivated this study.  相似文献   
89.
目的 利用网络药理学和分子对接技术研究石菖蒲抗癫痫的有效成分及作用机制。方法 运用中药系统药理数据库及分析平台检索石菖蒲有效成分及主要靶点,通过GeneCards数据库收集癫痫疾病的相关潜在作用靶点,运用Cytoscape.3.7.1和 String绘制石菖蒲-癫痫靶点互作关系图,运用Metascape数据库进行GO和KEGG信号通路富集分析。运用AutoDock Vina 1.1.2软件对石菖蒲主要有效成分与癫痫相关靶标进行分子对接验证;通过构建戊四唑诱导的癫痫模型初步评价石菖蒲提取物及潜在有效成分的抗癫痫作用。结果 由 TCMSP 筛选得到4个有效成分及76个主要靶点。癫痫疾病以“Score”大于1.5分进行筛选得到3685个靶标。GO富集分析得到BP条目10个,细胞CC条目9个,MF条目10个(P<0.01),主要涉及核受体活性、离子通道活性、激素结合、神经递质受体活性、蛋白激酶活性、钙调蛋白结合等。KEGG 富集得到14条通路,主要涉及c型凝集素受体信号通路、雌激素信号通路、Ca2+信号通路、逆行内源性大麻素信号通路等。分子对接结果显示,桉脂素、山奈酚和8-异戊烯基山奈酚与癫痫关键靶标GABRA2、PPARG等具有良好的结合活性。动物实验结果表明,石菖蒲水提取物及主要潜在有效成分桉脂素和山奈酚在PTZ致小鼠癫痫模型上显示出较好的抗癫痫活性。结论 本研究通过动物实验验证了石菖蒲提取物和潜在有效成分的抗癫痫活性,并且运用网络药理学和分子对接技术探讨了其抗癫痫作用机制,发现石菖蒲可通过多个成分如桉脂素、山奈酚、8-异戊烯基山奈酚,多靶点如GABAA、PPARG等,多条通路如雌激素信号通路、钙信号通路对机体产生协调效应从而抑制癫痫的发作。该研究提示石菖蒲治疗癫痫具有多成分、多靶点、多通路特点,为石菖蒲的进一步研究提供数据支撑。  相似文献   
90.
In low and middle-income countries mammographic breast cancer screening is prohibitively expensive and a cheaper alternative option is to use ultrasound as the primary screening test. In 2009, China launched a breast cancer screening programme for rural women aged 35–64 years with clinical breast examination coupled with ultrasound as the primary tool. Our study aimed to analyse the cost-effectiveness of breast screening compared to no screening among Chinese rural women. We developed a Markov model to estimate the lifetime costs and effects for rural women aged 35 years from a societal perspective. Asymptomatic women in the intervention arm were screened every 3 years before age 64 years. Breast cancer in the non-screening arm can only be diagnosed on presentation of symptoms. Parameter uncertainty was explored using one-way and probabilistic sensitivity analyses. Compared to no screening, breast cancer screening cost $186.7 more and led to a loss of 0.20 quality-adjusted life years (QALYs). Breast screening was more expensive and did harm to health among rural women with an incremental cost-effectiveness ratio (ICER) of $-916/QALY. The sensitivity analysis identified utility loss from false positives as the factor that most influenced the results, but this did not affect the conclusions. In a rural setting with such low breast cancer incidence, screening for asymptomatic disease is not cost-effective with current screening tools. Priority should be given to ensure that symptomatic women have proper access to diagnosis and treatment at an early stage as this will lead to mortality reductions without the usual screening harms.  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