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   195395篇
  免费   9337篇
  国内免费   2157篇
耳鼻咽喉   3196篇
儿科学   6690篇
妇产科学   4711篇
基础医学   27056篇
口腔科学   5227篇
临床医学   16096篇
内科学   34941篇
皮肤病学   4880篇
神经病学   17173篇
特种医学   9655篇
外国民族医学   45篇
外科学   30785篇
综合类   5170篇
现状与发展   5篇
一般理论   38篇
预防医学   9843篇
眼科学   5204篇
药学   14413篇
  23篇
中国医学   1750篇
肿瘤学   9988篇
  2023年   1188篇
  2022年   1196篇
  2021年   2690篇
  2020年   2195篇
  2019年   2228篇
  2018年   3818篇
  2017年   3264篇
  2016年   4076篇
  2015年   4876篇
  2014年   5257篇
  2013年   6683篇
  2012年   10231篇
  2011年   9846篇
  2010年   5809篇
  2009年   4629篇
  2008年   9001篇
  2007年   9752篇
  2006年   9804篇
  2005年   10194篇
  2004年   9388篇
  2003年   9120篇
  2002年   8998篇
  2001年   6728篇
  2000年   6845篇
  1999年   6087篇
  1998年   1980篇
  1997年   1690篇
  1996年   1292篇
  1995年   1069篇
  1994年   940篇
  1993年   848篇
  1992年   2612篇
  1991年   2493篇
  1990年   2429篇
  1989年   2272篇
  1988年   1983篇
  1987年   1964篇
  1986年   1812篇
  1985年   1735篇
  1984年   1324篇
  1983年   1054篇
  1979年   1393篇
  1978年   1021篇
  1977年   855篇
  1975年   1084篇
  1974年   1123篇
  1973年   1016篇
  1972年   1026篇
  1971年   1006篇
  1970年   894篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
中药(单体/复方)药效物质基础研究是中医药现代研究的关键问题之一。然而,目前运用的生化和分子生物学方法很难诠释其多靶点、整体性和动态性的整合调节作用。课题组提出的"证治代谢组学"假说理论指出,不同的证候存在"证相关代谢谱群"和"证相关生物标志物",这可能是中药药效物质基础所在,辨证论治后偏离的代谢网络功能呈现回归趋势。基于"证治代谢组学"假说开展中药(单体/复方)药效物质基础研究,这将为阐释中药(单体/复方)防病治病和养生保健的科学内涵及其对疾病个体的整合调节作用提供新的思路。本文以冠心病为研究载体、气阴虚血瘀证为切入点、活血保心丸为干预措施,就该研究思路的内涵与总体模式、提出的背景与依据、实践的方式与可行性、创新与特色及其研究意义等进行了简要介绍。  相似文献   
82.
83.
Der Freie Zahnarzt - Risiken und Nebenwirkungen im Gesundheitswesen. Wer sich heute mit Digitalisierung beschäftigt, kommt am Thema „Künstliche Intelligenz (KI)“ nicht vorbei....  相似文献   
84.

Personality differences are important determinants of problematic online behaviors. The purpose of the present study was to investigate the mediating role of loneliness, depression, and online gaming motives and moderating role of age on the relationship between trait emotional intelligence (EI) and Internet gaming disorder (IGD) via the construction of a multiple mediation model. A total of 478 online gamers completed a self-report online survey, including validated psychometric scales assessing the aforementioned constructs. Results indicated that trait EI was directly and indirectly associated with IGD and that the motive of escape was a partial mediator between trait EI and IGD among the total sample and adult gamers, but not among adolescents. Moreover, trait EI was associated with coping, skill development, fantasy, and recreation gaming motives only among total sample and adult gamers, and the escape motive was positively associated with IGD among total sample and adult gamers. However, among these relationships, only the association between trait EI and fantasy was significantly moderated by age group. Furthermore, the direct effect of trait EI was stronger among adolescent gamers when compared to adult gamers. Results showed that trait EI is inversely associated with IGD and affects gaming for different motives among adolescent and adult gamers.

  相似文献   
85.
目的了解结核病患者的心理状态,并给予相应治疗,以观察其疗效。方法采用医院焦虑抑郁情绪调查表,对2004年1月—2005年1月收治的130名结核病患者进行心理测评,对心理治疗前后患者心态的变化进行u检验。结果回收有效问卷123份,调查发现心理状态变异者占90.2%(111/123),其中焦虑型患者占56.1%(69/123),抑郁型患者占21.1%(26/123),无所用心型患者占13.0%(16/123),心理状态稳定者仅占9.8%(12/123)。给予相应心理治疗后患者心态较治疗前显著改善(P<0.01),心理状态变异者由治疗前的90.2%减少为治疗后的11.4%(14/123),心理状态稳定者由治疗前的9.8%提高到治疗后的88.6%(109/123)。结论结核病患者存在严重的心理问题,在治疗过程中开展心理治疗是十分必要的。  相似文献   
86.
BACKGROUND AND PURPOSE: There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed. MATERIAL AND METHODS: The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer. Three-dimensional conformal radiotherapy was used in eleven patients, another eleven patients received IMRT with 6-MV photons, and eight patients were treated with spot-scanned protons. The treatment plans were recalculated with 15-MV and 18-MV photons. Secondary cancer risk was estimated based on the OED for the different treatment techniques. RESULTS: A modest increase of 15% radiation-induced cancer results from IMRT using low energies (6 MV), compared to conventional four-field planning with 15-MV photons (plateau dose-response: 1%). The probability to develop a secondary cancer increases with IMRT of higher energies by 20% and 60% for 15 MV and 18 MV, respectively (plateau dose-response: 2% and 30%). The use of spot-scanned protons can reduce secondary cancer incidence as much as 50% (independent of dose-response). CONCLUSION: By including the primary dose distribution into the analysis of radiation-induced cancer incidence, the resulting increase in risk for secondary cancer using modern treatment techniques such as IMRT is not as dramatic as expected from earlier studies. By using 6-MV photons, only a moderate risk increase is expected. Spot-scanned protons are the treatment of choice in regard to secondary cancer incidence.  相似文献   
87.
Radiolabeled octreotide analogs (Oct) and metaiodobenzylguanidine (MIBG) offer 2 different approaches for imaging and targeting metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NET). Despite successful establishment of the revised World Health Organization (WHO) classification, which distinguishes between low- and high-grade malignant GEP-NET, there is a lack of scintigraphic studies comparing uptake behavior on the basis of this categorization. This study aims to define predisposing factors of tracer uptake for both imaging principles implementing the updated tumor criteria of the current WHO classification. METHODS: Fifty-seven consecutive patients with histologically confirmed metastatic GEP-NET evaluated with both 111In-pentetreotide and 123I/131I-MIBG scintigraphy were included in this study. Intensity of tracer uptake was graded according to the different metastatic regions. Patients were classified as overall positive when avid uptake in the clinically relevant tumor lesions was present. Correlation was tested between the proportion of positive patients and tumor origin, function, and malignancy. RESULTS: Overall, 52 patients (91.2%) were Oct positive and 28 patients (49.1%) were MIBG positive. The proportion of tracer-positive patients was significantly higher (P < 0.05) in low-grade malignant tumors for both tracers and in functioning as well as in gastroenteral NET for MIBG. Five patients were negative for both tracers. None of the Oct-negative patients proved to be MIBG positive. CONCLUSION: Oct affinity is observed with high frequency throughout the subgroups of metastatic GEP-NET, whereas corresponding MIBG uptake is overall less prevalent and more group dependent. Tumor differentiation significantly impacts both Oct and MIBG uptake, whereas functionality predisposes only for MIBG accumulation. Though clearly inferior to Oct-based radioimaging in most GEP-NET, MIBG achieves a remarkable rate of radioligand accumulation in functioning midgut enterochromaffin cell metastases (>80% of patients positive). These results may have implications for patient management and potentially for selection and performance of targeted therapy.  相似文献   
88.
During skeletal development the two ossification centers of the odontoid process are separated from the corpus of the axis by a subdental synchondrosis. This synchondrosis is thought to close and disappear spontaneously in adolescence although this has never been studied in detail. The basis of the dens is of clinical relevance as type II dens fractures are located here. To characterize the morphological architecture of the axis with particular attention to the subdental synchondrosis, the complete axis was harvested from thirty age-matched and gender-matched patients of the three different age groups at autopsy. The subdental synchondrosis and the bone structure of the dens, the basis of the dens and the body of C2 were analyzed by radiography, histology and quantitative histomorphometry. At the macroscopic level the persistency of the subdental synchondrosis in the adult cervical spine was detected in 87% (26 of 30) of the specimens. Histomorphometry revealed a residual disc blastema with an average size of 25.8% of the sagittal depth of the basis of the dens at this level. Bony integration of the synchondrosis was poor throughout all ages. Histologically a cartilaginous matrix composition of the subdental synchondrosis persisted throughout all groups. The trabecular microarchitecture demonstrated a significant reduction of bone volume and trabecular number as well as an increased trabecular separation within the basis of the dens as compared to the corpus or the dens of C2. This histomorphometric data regarding a poor integration of the synchondrosis into the trabecular network and the reduced bone mass within the basis of the dens might offer a previously underestimated explanation for the occurrence of type II dens fractures and their association with pseudoarthrosis, respectively.Matthias Gebauer and Christian Lohse contributed equally to this study and therefore share first authorship.  相似文献   
89.
不同强度运动对大鼠心脏降钙素基因相关肽的影响   总被引:5,自引:0,他引:5  
目的:探讨不同强度运动训练对降钙素基因相关肽(CGRP)在心脏组织中表达的影响及其作用机制。方法:将60只SD大鼠随机分为对照组(C组)、小强度运动组(LE组)、中等强度运动组(ME组)和大强度运动组(HE组),每组15只。建立8周不同强度运动训练动物模型,采用免疫组织化学法和计算机图像分析技术,对大鼠心脏形态结构进行观察,并进行心脏CGRP免疫组化分析。结果:8周小强度运动后,大鼠心脏CGRP表达较对照组变化不明显;8周中等强度运动后,大鼠心脏CGRP表达较对照组显著增加(P<0.05),HE染色、HBFP染色和变色酸2R亮绿染色显示心肌组织形态结构无明显改变,仅心肌纤维有轻度缺血缺氧改变;8周大强度运动后,大鼠心脏CGRP表达较对照组显著减少(P<0.05),HE染色、HBFP染色和变色酸2R亮绿染色显示心肌形态结构发生改变并存在明显的缺血缺氧损伤。结果表明,长期中等强度运动使心脏CGRP表达增加,改善了冠状循环和心肌血液供应,对心肌细胞具有保护作用;长期大强度运动使心脏CGRP对心肌细胞的保护作用减弱,可能是导致心肌发生缺血缺氧性损伤的重要原因之一。  相似文献   
90.
Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.  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