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   7885篇
  免费   815篇
  国内免费   478篇
耳鼻咽喉   31篇
儿科学   37篇
妇产科学   73篇
基础医学   1098篇
口腔科学   80篇
临床医学   1090篇
内科学   1465篇
皮肤病学   60篇
神经病学   431篇
特种医学   278篇
外国民族医学   15篇
外科学   858篇
综合类   927篇
现状与发展   4篇
预防医学   456篇
眼科学   68篇
药学   812篇
  35篇
中国医学   585篇
肿瘤学   775篇
  2024年   21篇
  2023年   155篇
  2022年   397篇
  2021年   638篇
  2020年   482篇
  2019年   423篇
  2018年   418篇
  2017年   360篇
  2016年   391篇
  2015年   568篇
  2014年   658篇
  2013年   624篇
  2012年   760篇
  2011年   786篇
  2010年   506篇
  2009年   405篇
  2008年   385篇
  2007年   349篇
  2006年   306篇
  2005年   326篇
  2004年   64篇
  2003年   58篇
  2002年   25篇
  2001年   17篇
  2000年   14篇
  1999年   9篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1988年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1964年   1篇
排序方式: 共有9178条查询结果,搜索用时 171 毫秒
111.
112.
Background:Alzheimer disease (AD) is a progressive neurodegenerative disease characterized by impaired memory and cognitive judgment. It is the leading cause of dementia in the elderly, and its high morbidity and mortality have also brought a significant social burden. So far, there is no method can completely cure Alzheimer''s dementia, but there are many non-drug treatments that have been praised by people, especially the cognitive behavioral therapy proposed in recent years. The main purpose of this article is to evaluate the effect of cognitive behavioral therapy on the cognitive function improvement of patients with Alzheimer''s dementia.Methods:We did a network meta-analysis to identify both direct and indirect evidence in relevant studies. A systematic literature search will be performed in the Cochrane Library, PubMed, and EMBASE from inception to October 2020. We extracted the relevant information from these trials with a predefined data extraction sheet and assessed the risk of bias with the Cochrane risk of bias tool.The outcomes investigated were Mini–Mental State Examination and AD Assessment Scale-Cognitive section scores. We did a pair-wise meta-analysis using the fixed-effects model and then did a random-effects network meta-analysis within a Bayesian framework. The = the Assessment of Multiple Systematic Reviews-2 scale, Preferred Reporting Items for Systematic Reviews and Meta-Analyses scale and Grading of Recommendations Assessment, Development and Evaluation were used to assess the quality and evidence grade of the literature. General characteristics of the eligible randomized controlled trials will be summarized and described. Meanwhile, The ADDIS software will be used to perform the network meta-analysis, and the result figures will be generated by STATA 15.0 software.Results:Using the draft search strategy of databases and after screening,7 randomized controlled trials met the a priori criteria and were included. This network mate-analysis will be published in a peer-reviewed journal.Conclusion:Our study will provide evidence for cognitive behavioral intervention in AD patients. And provide recommendations and guidelines for the clinic.Protocol Registration:INPLASY2020110052.  相似文献   
113.

Aim:

SMXZF (a combination of ginsenoside Rb1, ginsenoside Rg1, schizandrin and DT-13) derived from Chinese traditional medicine formula ShengMai preparations) is capable of alleviating cerebral ischemia-reperfusion injury in mice. In this study we used network pharmacology approach to explore the mechanisms of SMXZF in the treatment of cardio-cerebral ischemic diseases.

Methods:

Based upon the chemical predictors, such as chemical structure, pharmacological information and systems biology functional data analysis, a target-pathway interaction network was constructed to identify potential pathways and targets of SMXZF in the treatment of cardio-cerebral ischemia. Furthermore, the most related pathways were verified in TNF-α-treated human vascular endothelial EA.hy926 cells and H2O2-treated rat PC12 cells.

Results:

Three signaling pathways including the NF-κB pathway, oxidative stress pathway and cytokine network pathway were demonstrated to be the main signaling pathways. The results from the gene ontology analysis were in accordance with these signaling pathways. The target proteins were found to be associated with other diseases such as vision, renal and metabolic diseases, although they exerted therapeutic actions on cardio-cerebral ischemic diseases. Furthermore, SMXZF not only dose-dependently inhibited the phosphorylation of NF-κB, p50, p65 and IKKα/β in TNF-α-treated EA.hy926 cells, but also regulated the Nrf2/HO-1 pathway in H2O2-treated PC12 cells.

Conclusion:

NF-κB signaling pathway, oxidative stress pathway and cytokine network pathway are mainly responsible for the therapeutic actions of SMXZF against cardio-cerebral ischemic diseases.  相似文献   
114.
目的探讨连续血液净化(CBP)对重症脓毒症合并应激性心肌病患者的疗效。方法回顾性收集2012年1月至2014年1月60例重症脓毒症合并应激性心肌病患者,分为常规治疗组30例和血液净化组30例,分析2组治疗前、治疗后24、48、72 h相关血流动力学及72 h炎症感染指标变化。结果CBP治疗后患者平均动脉压、心率、每搏输出量、左心室射血分数和氧合指数(Pa O2/Fi O2)均较治疗前有所改善(P<0.05);与常规治疗组相比,CBP治疗组在C-反应蛋白、降钙素原、白细胞介素-6、脑利钠肽及血乳酸等指标均降低(P<0.05),氧合指数上升(P<0.05),急性生理学及慢性健康状况评分Ⅱ(APACHEⅡ)亦降低(P<0.05)。结论对于重症脓毒症合并应激性心肌病患者采用连续性血液净化治疗,在早期能有效清除炎症因子,维持血流动力学稳定,改善氧合功能。  相似文献   
115.
Journal of Thrombosis and Thrombolysis - Patients undergoing percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) are at increased risk for thrombotic and bleeding...  相似文献   
116.
Although vaccine and passive immunotherapy were widely used to prevent goose parvovirus (GPV) infection in goose industry, GPV still poses a big problem in Southeastern China. In this study, 23 GPV isolates were isolated from goslings suspected with GPV infection in Southeastern China during 2012–2013, and the genetic diversity of VP3 of GPV was analyzed. Phylogenetic tree revealed that these isolates could be clustered into two groups, and 11 of 23 could be further clustered into a new subgroup. Moreover, eight novel mutations and seventeen conserved amino acids were found in these 23 isolates in comparison with isolates previously deposited in GenBank. These isolates and findings not only provide insights into the etiology and molecular characteristics of GPV endemic in Southeastern China, but also enrich the GPV genetic information for better controlling the disease.  相似文献   
117.
Aprotic lithium-oxygen (Li-O2) batteries have gained extensive interest in the past decade, but are plagued by slow reaction kinetics and induced large-voltage hysteresis. Herein, we use a plasmonic heterojunction of Au nanoparticle (NP)–decorated C3N4 with nitrogen vacancies (Au/NV-C3N4) as a bifunctional catalyst to promote oxygen cathode reactions of the visible light–responsive Li-O2 battery. The nitrogen vacancies on NV-C3N4 can adsorb and activate O2 molecules, which are subsequently converted to Li2O2 as the discharge product by photogenerated hot electrons from plasmonic Au NPs. While charging, the holes on Au NPs drive the reverse decomposition of Li2O2 with a reduced applied voltage. The discharge voltage of the Li-O2 battery with Au/NV-C3N4 is significantly raised to 3.16 V under illumination, exceeding its equilibrium voltage, and the decreased charge voltage of 3.26 V has good rate capability and cycle stability. This is ascribed to the plasmonic hot electrons on Au NPs pumped from the conduction bands of NV-C3N4 and the prolonged carrier life span of Au/NV-C3N4. This work highlights the vital role of plasmonic enhancement and sheds light on the design of semiconductors for visible light–mediated Li-O2 batteries and beyond.

The aprotic lithium-oxygen (Li-O2) battery promises ultrahigh theoretical energy density (∼3,600 Wh·kg−1) and is operated with oxygen reduction to generate the product of Li2O2 and its reverse oxidation (2Li+ + O2 + 2e ↔ Li2O2, E0 = 2.96 V) (15). The sluggish oxygen cathode reactions, including the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), lead to a high discharge/charge overvoltage (∼1.0 V) during cycles and low round-trip efficiency (69). Since the pioneering work on the photoinvolved Li-O2 battery using TiO2 (10) or C3N4 (11) under ultraviolet (UV)-light irradiation, reduction of the charge/discharge overvoltage via a photomediated strategy has been extensively studied and is anticipated to solve the kinetic issues of the Li-O2 battery (1218). However, the light absorption of most semiconductors used is confined in the region of UV light, accounting for only ca. 4% of the solar spectrum (1416). Expanding the light harvesting from UV to visible light is the long-term goal and challenge of photocatalysis (1720). Simultaneously, high carrier recombination consumes the majority of photoelectrons and holes before catalyzing the targeted reactions, resulting in a mismatch between the carrier lifetime and kinetics of ORR or OER (1921). This necessitates a structural design of semiconducting materials for visible-light harvesting to accelerate the cathode reactions in Li-O2 batteries.Localized surface plasmon resonance (LSPR), which refers to the collective oscillation of conduction band (CB) electrons in metal nanocrystals under resonant excitation, has recently gained much attention (2225). The decay of excited LSPR can produce hot electrons and holes, which initiate various chemical reactions (22, 23). Intriguingly, when plasmonic metal (e.g., Au, Ag) nanoparticles (NPs) come into contact with a semiconductor such as MoS2, TiO2, etc., an interfacial Schottky barrier forms; this barrier functions as a filter to force the energetic electrons or holes to migrate across the interface while inhibiting their reverse movement, thereby leading to effective electron–hole separation and suppressed charge–carrier recombination (2630). LSPR systems generally are composed of plasmonic metal and semiconductors and exhibit the benefits of a low electron–hole recombination rate, enhanced light harvesting, and tailored response wavelengths from the visible to the near-infrared region (22). Recently, Au/CdSe (31) and Au/Ni(OH)2 (32) heterojunctions have been attempted for a photocatalytic hydrogen evolution reaction and OER with the aid of hot electrons and holes under visible light. Coupling the plasmonic metal with suitable semiconductors for broadened light harvesting and a plasmon-enhanced effect is highly desirable for both ORR and OER in the Li-O2 battery.Herein, we report defective C3N4 (Au/NV-C3N4) decorated with plasmonic Au NPs as a bifunctional heterojunction catalyst that promotes cathode reactions of the Li-O2 battery under visible light. The NV on NV-C3N4 is prone to adsorb and activate O2, and the plasmon-excited electrons on Au migrate to the CB of NV-C3N4 and relax to the NV-induced defect band (DB) for O2 reduction to LiO2; then it undergoes electron reduction to Li2O2. Reversely, the Li2O2 is removed by the holes on the Au NPs driven by the applied voltage. The discharge voltage is raised to 3.16 V, and the charge voltage is lowered to 3.26 V at 0.05 mA·cm−2 with a good rate capability and cycle stability. This investigation integrates a plasmonic heterojunction into the aprotic Li-O2 battery and illustrates photoenergy conversion and storage under visible light.  相似文献   
118.
In early life, over-nutrition may increase the risk of insulin resistance in the adult stage. Adiponectin and its receptor may play a key role in this process. This study aimed to identify the effect of a high-fat (HF) maternal diet on metabolic parameters and muscle adiponectin signaling in young adult offspring. We found that offspring born to dams fed HF chow (HF; 31% of calories from fat) had elevated body and adipose tissue weight and higher serum glucose levels after glucose challenge at three weeks (W3) and eight weeks (W8) of age. Offspring exposed to a HF diet also had higher serum adiponectin levels at W3 compared to controls. However, adiponectin levels were significantly decreased compared to controls by W8. Adiponectin receptor 1?mRNA expression in skeletal muscle was decreased in the HF group at W3 and W8, and there was no difference between the two groups in adiponectin receptor 2 expression. Furthermore, glucose transporter 4?mRNA and protein expression was decreased in the skeletal muscle of the HF group at W3 and W8. Our results suggest that a HF maternal diet decreases adiponectin receptor 1 expression in the offspring, which could contribute to reduced sensitivity to adiponectin and to adverse nutritional programing outcomes.  相似文献   
119.
目的 探讨艾滋病合并肺结核的临床特点及治疗。方法 对24例艾滋病合并肺结核进行回顾性分析。结果 两病并发率由1998年的0.05%上升至2002年的0.73%。HIV感染途径为静脉吸毒(77.1%)及性途径(22.9%);临床表现有发热(91.7%),咳嗽(91.7%),咳痰(79.2%),明显消瘦(79.2%),淋巴结肿大(54.7%);胸部X线表现以继发性肺结核为主(66.7%);合并病毒性肝炎50%,痰菌阳性率41.7%,PPD试验阳性率16.7%,14例抗结核治疗(3HRZE/9HRE)治愈或完成疗程,抗结核药物不良反应发生率为79.2%。结论 艾滋病合并肺结核常发病急、症状重、PPD试验阳性率低、抗结核药物治疗不良反应多,应加强艾滋病高发区及高危人群肺结核患者并发艾滋病的警惕性。  相似文献   
120.
To guarantee the long-term stability of an orthopaedic implant, non-degradable surface coatings with the ability to selectively release bioactive drugs or ions are especially desirable. In this study, SrO–TiO2 composite coatings were deposited on the surface of Ti alloys, whose release behavior of bioactive Sr ions was modulated by the Sr configurations, either interstitial atoms in solid solution (TiySr2−2yO2) or strontium titanate (SrTiO3). A perfect linear relationship between the amount of the released Sr ions and the Sr content in the coating was observed. Among the SrO-doped TiO2 coatings, the 20% SrO–TiO2 coating where Sr existed in both forms of TiySr2−2yO2 and SrTiO3 not only promoted proliferation of bone cells but also enhanced their osteogenic differentiation, which was proved to be related to its Sr release behavior. However, overdosing with 30% SrO only resulted in one single Sr configuration (SrTiO3) and an inferior osteogenic function. This study suggests that Sr configurations of both interstitial atoms of the solid solution and SrTiO3 can realize the selective release of Sr, but they possibly have different effects on the biological functions and other properties including corrosion resistance.

Strontium configurations can modulate its release in the SrO–TiO2 coating system, thus being able to control the interfacial osteogenesis.  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