全文获取类型
收费全文 | 845篇 |
免费 | 75篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 41篇 |
妇产科学 | 3篇 |
基础医学 | 97篇 |
口腔科学 | 17篇 |
临床医学 | 137篇 |
内科学 | 135篇 |
皮肤病学 | 14篇 |
神经病学 | 64篇 |
特种医学 | 61篇 |
外科学 | 93篇 |
综合类 | 21篇 |
预防医学 | 55篇 |
眼科学 | 50篇 |
药学 | 57篇 |
中国医学 | 7篇 |
肿瘤学 | 61篇 |
出版年
2023年 | 8篇 |
2022年 | 18篇 |
2021年 | 39篇 |
2020年 | 20篇 |
2019年 | 33篇 |
2018年 | 28篇 |
2017年 | 21篇 |
2016年 | 22篇 |
2015年 | 33篇 |
2014年 | 23篇 |
2013年 | 37篇 |
2012年 | 53篇 |
2011年 | 46篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 45篇 |
2007年 | 45篇 |
2006年 | 42篇 |
2005年 | 28篇 |
2004年 | 37篇 |
2003年 | 25篇 |
2002年 | 27篇 |
2001年 | 18篇 |
2000年 | 18篇 |
1999年 | 23篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1971年 | 3篇 |
1946年 | 2篇 |
1936年 | 2篇 |
1931年 | 3篇 |
1927年 | 5篇 |
1926年 | 3篇 |
排序方式: 共有924条查询结果,搜索用时 31 毫秒
21.
Nguyen Ha Anh Mai Quan Doan Ngo Xuan Dinh Tran Quang Huy Doan Quang Tri Le Thi Ngoc Loan Bui Van Hao Anh-Tuan Le 《RSC advances》2022,12(18):10950
Modern society has been facing serious health-related problems including food safety, diseases and illness. Hence, it is urgent to develop analysis methods for the detection and control of food contaminants, disease biomarkers and pathogens. As the traditional instrumental methods have several disadvantages, including being time consuming, and having high cost and laborious procedures, optical nanosensors have emerged as promising alternative or complementary approaches to those traditional ones. With the advantages of simple preparation, high surface-to-volume ratio, excellent biocompatibility, and especially, unique optical properties, gold nanoparticles (AuNPs) have been demonstrated as excellent transducers for optical sensing systems. Herein, we provide an overview of the synthesis of AuNPs and their excellent optical properties that are ideal for the development of optical nanosensors based on local surface plasmon resonance (LSPR), colorimetry, fluorescence resonance energy transfer (FRET), and surface-enhanced Raman scattering (SERS) phenomena. We also review the sensing strategies and their mechanisms, as well as summarizing the recent advances in the monitoring of food contaminants, disease biomarkers and pathogens using developed AuNP-based optical nanosensors in the past seven years (2015–now). Furthermore, trends and challenges in the application of these nanosensors in the determination of those analytes are discussed to suggest possible directions for future developments.We provide an overview of the synthesis of AuNPs and their excellent optical properties for the development of optical nanosensors including colorimetric, fluorescence resonance energy transfer, and surface-enhanced Raman scattering sensors. 相似文献
22.
Alpinia Roxb. is the largest genus of the Zingiberaceae family. A large number of Alpinia species has been used as food and traditional medicines. Alpinia essential oils have been studied for their chemical profiles, in which 1,8-cineole, β-pinene, α-pinene, β-myrcene, camphor, γ-terpinene, p-cymene, geraniol, α-fenchyl acetate, ocimene, methyl cinnamate, and β-caryophyllene have been found to be the major compounds. Essential oils isolated from Alpinia plants have been reported to have antimicrobial, cytotoxic, antioxidant, anti-inflammatory, anti-asthmatic, tyrosinase inhibitory, insecticidal, and larvicidal activities and slimming aromatherapy. In this review, the comprehensive information regarding the volatile components of various Alpinia plants, the bioactivities of Alpinia essential oils and their major compounds are provided. Alpinia Roxb. is the largest genus of the Zingiberaceae family. 相似文献
23.
Thi Le Anh Nguyen Thi Hoai Nam Doan Dinh Hieu Truong Nguyen Thi Ai Nhung Duong Tuan Quang Dorra Khiri Sonia Taamalli Florent Louis Abderrahman El Bakali Duy Quang Dao 《RSC advances》2021,11(35):21433
Antioxidant and UV absorption activities of three aaptamine derivatives including piperidine[3,2-b]demethyl(oxy)aaptamine (C1), 9-amino-2-ethoxy-8-methoxy-3H-benzo[de][1,6]naphthyridine-3-one (C2), and 2-(sec-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-ij][1,6]-naphthyridin-10(9H)-one (C3) were theoretically studied by density functional theory (DFT). Direct antioxidant activities of C1–C3 were firstly evaluated via their intrinsic thermochemical properties and the radical scavenging activity of the potential antioxidants with the HOO˙/HO˙ radicals via four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO˙ scavenging in water occurs via HAT mechanism with C1 (kapp, 7.13 × 106 M−1 s−1) while RAF is more dominant with C2 (kapp, 1.40 × 105 M−1 s−1) and C3 (kapp, 2.90 × 105 M−1 s−1). Antioxidant activity of aaptamine derivatives can be classified as C1 > C3 > C2. Indirect antioxidant properties based on Cu(i) and Cu(ii) ions chelating activity were also investigated in aqueous phase. All three studied compounds show spontaneous and favorable Cu(i) ion chelating activity with ΔG0 being −15.4, −13.7, and −15.7 kcal mol−1, whereas ΔG0 for Cu(ii) chelation are −10.4, −10.8, and −2.2 kcal mol−1 for C1, C2 and C3, respectively. In addition, all compounds show UVA and UVB absorption; in which the excitations are determined mostly as π–π* transition. Overall, the results suggest the potential applications of the aaptamines in pharmaceutics and cosmetics, i.e. as a sunscreen and antioxidant ingredient.Antioxidant and UV absorption activities of three aaptamine derivatives were theoretically studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). 相似文献
24.
Coronary artery disease remains the major cause of perioperative mortality after abdominal aortic aneurysm (AAA) repair. The
beneficial effect of coronary artery bypass (CAB) before AAA repair in patients with severe coronary artery disease has been
proven. The coexistence of a very large or symptomatic AAA and coronary artery disease remains a therapeutic challenge since
there is the risk of AAA rupture in the interval between CAB and AAA repair. Combined CAB and aortic aneurysm repair has been
suggested for these cases, and results on several series of patients have been published. However, the exact indication for
the combined operation remains to be clarified. We present a series of 13 patients who underwent CAB on cardiopulmonary bypass
and aortic aneurysm repair as a one-stage procedure. The indication was a large AAA in seven patients and a symptomatic AAA
in six patients. In four patients, the aortic reconstruction was performed without the use of cardiopulmonary bypass; in nine
patients, the aortic reconstruction was performed under partial cardiopulmonary bypass. Thirty-day mortality was 15%. Major
morbidity was 31%. All major complications were due to excessive bleeding and occurred in patients who had AAA repair performed
with partial cardiopulmonary bypass, suggesting that prolonged bypass time represents a major source of morbidity. A detailed
review of the literature is presented. From the evidence available we suggest that the combined procedure can be recommended
only for patients with very high rupture risk, such as in symptomatic AAA. In all other cases, the staged approach — CAB followed
by AAA repair 2-4 weeks later — is preferable. During the combined procedure, cardiopulmonary bypass support during AAA repair
should be used only in patients with clear evidence of hemodynamic instability. 相似文献
25.
Jason Howitt Ulrich Putz Jenny Lackovic Anh Doan Loretta Dorstyn Hong Cheng Baoli Yang Tailoi Chan-Ling John Silke Sharad Kumar Seong-Seng Tan 《Proceedings of the National Academy of Sciences of the United States of America》2009,106(36):15489-15494
The regulation of metal ion transport within neurons is critical for normal brain function. Of particular importance is the regulation of redox metals such as iron (Fe), where excess levels can contribute to oxidative stress and protein aggregation, leading to neuronal death. The divalent metal transporter 1 (DMT1) plays a central role in the regulation of Fe as well as other metals; hence, failure of DMT1 regulation is linked to human brain pathology. However, it remains unclear how DMT1 is regulated in the brain. Here, we show that DMT1 is regulated by Ndfip1 (Nedd4 family-interacting protein 1), an adaptor protein that recruits E3 ligases to ubiquitinate target proteins. Using human neurons we show the Ndfip1 is upregulated and binds to DMT1 in response to Fe and cobalt (Co) exposure. This interaction results in the ubiquitination and degradation of DMT1, resulting in reduced metal entry. Induction of Ndfip1 expression protects neurons from metal toxicity, and removal of Ndfip1 by shRNAi results in hypersensitivity to metals. We identify Nedd4–2 as an E3 ligase recruited by Ndfip1 for the ubiquitination of DMT1 within human neurons. Comparison of brains from Ndfip1−/− with Ndfip1+/+ mice exposed to Fe reveals that Ndfip1−/− brains accumulate Fe within neurons. Together, this evidence suggests a critical role for Ndfip1 in regulating metal transport in human neurons. 相似文献
26.
27.
28.
Theodore M. Hammett Giulia D. Norton Ryan Kling Wei Liu Yi Chen Doan Ngu Kieu Thanh Binh Ha Viet Dong Don C. Des Jarlais 《Journal of urban health》2005,82(4):iv34-iv42
Success of HIV prevention projects for injection drug users (IDUs) depends on the support of the communities in which they are implemented. This article presents data from cross-sectional community surveys of HIV knowledge and attitudes toward peer-based HIV prevention interventions for injection drug users in a border area of Lang Son Province, Vietnam and Ning Ming County, Guangxi Province, China. Analysis of these surveys at baseline and 18 months reveals generally high or improving levels of HIV knowledge and positive attitudes toward the interventions in both Vietnam and China. Levels of knowledge and positive attitudes tended to be higher in Vietnam than in China. Interviews with staff and peer educators suggest that the project’s community education efforts have increased support for the interventions and contributed to their smooth implementation. However, the community surveys also reveal some continuing deficits in HIV knowledge and understanding of the interventions, including perceptions that provision of new needles/syringes will result in increased drug use. Additional education, including dissemination of countervailing project data, is necessary to address these deficits and further increase community support for the interventions. 相似文献
29.
Exchange transfusion in neutropenic septicemic neonates: effect on granulocyte functions 总被引:1,自引:0,他引:1
NB Mathur BKM Subramanian VK Sharma RK Puri 《Acta paediatrica (Oslo, Norway : 1992)》1993,82(12):939-943
Depletion neutropenia caused by overwhelming bacterial infection is associated with fatal outcome and is an objective indicator of the severity of sepsis. Studies on controlled evaluation of exchange transfusion in the management of severe neonatal sepsis have not considered neutropenia as an inclusion critcrion, and randomized, controlled trials on evaluation of ncutrophil functions after exchange transfusion are scarce. This prompted us to carry out the present study. Septicemic neonates were enrolled if they had neutropenia and were randomized to undergo exchange transfusion (study group, n = 20) or not (controls, n= 10). Granulocyte functions were assessed using the nitro blue tetrazolium (NBT) reduction test and the staphylococcicidal index. Blood was drawn for granulocyte function tests once from controls and donors, and before, immediately after and 6 h after exchange transfusion in the study group. Mortality was 35% in the study group and 70% in controls. Gram-negative organisms accounted for 80%, in the study group and 90% in controls. Mean total leukocyte count and neutrophil count increased significantly immediately after exchange transfusion and 6 h later. Absolute band count decreased significantly immediately after exchange transfusion and incrcased 6 h later. NBT reduction in septicemic neonates in the study group, as wclras in controls. was significantly decreascd as compared to donor cells. NBT reduction improved significantly immediately after exchange transfusion and 6 h later. The valucs of the perccntage of viable staphylococci recovered from neutrophils also improved significantly immediately after exchange transfusion and 6 h later. We conclude that exchange transfusion with fresh whole blood in severe neonatal septicemia with neutropenia improves survival, increases the neutrophil count and cnhances neutrophil function. 相似文献
30.