全文获取类型
收费全文 | 1364篇 |
免费 | 78篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 18篇 |
妇产科学 | 27篇 |
基础医学 | 296篇 |
口腔科学 | 4篇 |
临床医学 | 128篇 |
内科学 | 333篇 |
皮肤病学 | 9篇 |
神经病学 | 192篇 |
特种医学 | 31篇 |
外科学 | 103篇 |
综合类 | 4篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 59篇 |
眼科学 | 13篇 |
药学 | 100篇 |
中国医学 | 5篇 |
肿瘤学 | 125篇 |
出版年
2024年 | 3篇 |
2023年 | 41篇 |
2022年 | 74篇 |
2021年 | 134篇 |
2020年 | 47篇 |
2019年 | 71篇 |
2018年 | 60篇 |
2017年 | 31篇 |
2016年 | 44篇 |
2015年 | 62篇 |
2014年 | 55篇 |
2013年 | 66篇 |
2012年 | 85篇 |
2011年 | 96篇 |
2010年 | 56篇 |
2009年 | 43篇 |
2008年 | 72篇 |
2007年 | 78篇 |
2006年 | 78篇 |
2005年 | 81篇 |
2004年 | 55篇 |
2003年 | 35篇 |
2002年 | 23篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1987年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1451条查询结果,搜索用时 0 毫秒
41.
Boris Ionin Robert J. Hopkins Brett Pleune Gloria S. Sivko Frances M. Reid Kristin H. Clement Thomas L. Rudge Jr. Gregory V. Stark Alison Innes Suha Sari Tina Guina Cris Howard Jeffrey Smith M. Lisa Swoboda Ekaterina Vert-Wong Virginia Johnson Gary S. Nabors Mario H. Skiadopoulos 《Clinical and Vaccine Immunology : CVI》2013,20(7):1016-1026
Antimicrobials administered postexposure can reduce the incidence or progression of anthrax disease, but they do not protect against the disease resulting from the germination of spores that may remain in the body after cessation of the antimicrobial regimen. Such additional protection may be achieved by postexposure vaccination; however, no anthrax vaccine is licensed for postexposure prophylaxis (PEP). In a rabbit PEP study, animals were subjected to lethal challenge with aerosolized Bacillus anthracis spores and then were treated with levofloxacin with or without concomitant intramuscular (i.m.) vaccination with anthrax vaccine adsorbed (AVA) (BioThrax; Emergent BioDefense Operations Lansing LLC, Lansing, MI), administered twice, 1 week apart. A significant increase in survival rates was observed among vaccinated animals compared to those treated with antibiotic alone. In preexposure prophylaxis studies in rabbits and nonhuman primates (NHPs), animals received two i.m. vaccinations 1 month apart and were challenged with aerosolized anthrax spores at day 70. Prechallenge toxin-neutralizing antibody (TNA) titers correlated with animal survival postchallenge and provided the means for deriving an antibody titer associated with a specific probability of survival in animals. In a clinical immunogenicity study, 82% of the subjects met or exceeded the prechallenge TNA value that was associated with a 70% probability of survival in rabbits and 88% probability of survival in NHPs, which was estimated based on the results of animal preexposure prophylaxis studies. The animal data provide initial information on protective antibody levels for anthrax, as well as support previous findings regarding the ability of AVA to provide added protection to B. anthracis-infected animals compared to antimicrobial treatment alone. 相似文献
42.
Alexey A. Moskalev Mikhail V. Shaposhnikov Ekaterina N. Plyusnina Alex Zhavoronkov Arie Budovsky Hagai Yanai Vadim E. Fraifeld 《Ageing research reviews》2013,12(2):661-684
Since the first publication on Somatic Mutation Theory of Aging (Szilárd, 1959), a great volume of knowledge in the field has been accumulated. Here we attempted to organize the evidence “for” and “against” the hypothesized causal role of DNA damage and mutation accumulation in aging in light of four Koch-like criteria. They are based on the assumption that some quantitative relationship between the levels of DNA damage/mutations and aging rate should exist, so that (i) the longer-lived individuals or species would have a lower rate of damage than the shorter-lived, and (ii) the interventions that modulate the level of DNA damage and repair capacity should also modulate the rate of aging and longevity and vice versa. The analysis of how the existing data meets the proposed criteria showed that many gaps should still be filled in order to reach a clear-cut conclusion. As a perspective, it seems that the main emphasis in future studies should be put on the role of DNA damage in stem cell aging. 相似文献
43.
44.
Vanya Mantareva Vesselin Kussovski Mahmut Durmuş Ekaterina Borisova Ivan Angelov 《Lasers in medical science》2016,31(8):1591-1598
Photodynamic inactivation (PDI) is a light-associated therapeutic approach suitable for treatment of local acute infections. The method is based on specific light-activated compound which by specific irradiation and in the presence of molecular oxygen produced molecular singlet oxygen and other reactive oxygen species, all toxic for pathogenic microbial cells. The study presents photodynamic impact of two recently synthesized water-soluble cationic lutetium (III) acetate phthalocyanines (LuPc-5 and LuPc-6) towards two pathogenic strains, namely, the Gram-negative bacterium Pseudomonas aeruginosa and a fungus Candida albicans. The photodynamic effect was evaluated for the cells in suspensions and organized in 48-h developed biofilms. The relatively high levels of uptakes of LuPc-5 and LuPc-6 were determined for fungal cells compared to bacterial cells. The penetration depths and distribution of both LuPcs into microbial biofilms were investigated by means of confocal fluorescence microscopy. The photoinactivation efficiency was studied for a wide concentration range (0.85–30 μM) of LuPc-5 and LuPc-6 at a light dose of 50 J cm?2 from red light-emitting diode (LED; 665 nm). The PDI study on microbial biofilms showed incomplete photoinactivation (<3 logs) for the used gentle drug-light protocol. 相似文献
45.
Ekaterina Urch Samuel A. Taylor Elizabeth Cody Peter D. Fabricant Jayme C. Burket Stephen J. O’Brien David M. Dines Joshua S. Dines 《HSS journal》2016,12(3):209-215
Background
The internet has an increasing role in both patient and physician education. While several recent studies critically appraised the quality and accuracy of web-based written information available to patients, no studies have evaluated such parameters for open-access video content designed for provider use.Questions/Purposes
The primary goal of the study was to determine the accuracy of internet-based instructional videos featuring the shoulder physical examination.Methods
An assessment of quality and accuracy of said video content was performed using the basic shoulder examination as a surrogate for the “best-case scenario” due to its widely accepted components that are stable over time. Three search terms (“shoulder,” “examination,” and “shoulder exam”) were entered into the four online video resources most commonly accessed by orthopaedic surgery residents (VuMedi, G9MD, Orthobullets, and YouTube). Videos were captured and independently reviewed by three orthopaedic surgeons. Quality and accuracy were assessed in accordance with previously published standards.Results
Of the 39 video tutorials reviewed, 61% were rated as fair or poor. Specific maneuvers such as the Hawkins test, O’Brien sign, and Neer impingement test were accurately demonstrated in 50, 36, and 27% of videos, respectively. Inter-rater reliability was excellent (mean kappa 0.80, range 0.79–0.81).Conclusion
Our results suggest that information presented in open-access video tutorials featuring the physical examination of the shoulder is inconsistent. Trainee exposure to such potentially inaccurate information may have a significant impact on trainee education.46.
Lopez-Ramirez Felipe Gushchin Vadim Sittig Michelle King Mary Caitlin Baron Ekaterina Nikiforchin Andrei Nieroda Carol Sardi Armando 《Annals of surgical oncology》2022,29(6):3404-3404
Annals of Surgical Oncology - 相似文献
47.
Daria Gognieva Yulia Mitina Timur Gamilov Roman Pryamonosov Yuriy Vasilevskii Sergey Simakov Fuyou Liang Sergey Ternovoy Natalya Serova Ekaterina Tebenkova Valentin Sinitsyn Ekaterina Pershina Sergey Abugov Gaik Mardanian Narek Zakarian Vardan Kirakosian Vladimir Betelin Dmitry Shchekochikhin Abram Syrkin Philippe Kopylov 《Global Heart》2021,16(1)
Background:Until recently, Russia did not utilize noninvasive fractional flow reserve (FFR) assessment. We developed an automated algorithm for noninvasive assessment of FFR based on a one-dimensional (1D) mathematical modeling.Objective:The research aims to evaluate the diagnostic accuracy of this algorithm.Methods:The study enrolled 80 patients: 16 of them underwent 64-slice computed tomography – included retrospectively, 64 – prospectively, with a 640-slice CT scan. Specialists processed CT images and evaluated noninvasive FFR. Ischemia was confirmed if FFR < 0.80 and disproved if FFR ≥ 0.80. The prospective group of patients was hospitalized for invasive FFR assessment as a reference standard. If ischemic, patients underwent stent implantation. In the retrospective group, patients already had invasive FFR values.Statistical analysis was performed using GraphPad Prism 8. We compared two methods using a Bland–Altman plot and per-vessel ROC curve analysis. Considering the abnormality of distribution by the Kolmogorov-Smirnov test, we have used Spearman’s rank correlation coefficient.Results:During data processing, three patients of the retrospective and 46 patients of the prospective group were excluded. The sensitivity of our method was 66.67% (95% CI: 46.71–82.03); the specificity was 78.95% (95% CI: 56.67–91.49), p = 0.0052, in the per-vessel analysis. In per-patient analysis, the sensitivity was 69.57% (95% CI: 49.13–84.40); the specificity was 87.50% (95% CI: 52.91–99.36), p = 0.0109. The area under the ROC curve in the per-vessel analysis was 77.52% (95% CI: 66.97–88.08), p < 0.0001.Conclusion:The obtained indices of sensitivity, specificity, PPV, and NPV are, in general, comparable to those in other studies. Moreover, the noninvasive values of FFR yielded a high correlation coefficient with the invasive values. However, the AUC was not high enough, 77.52 (95% CI: 66.97–88.08), p < 0.0001. The discrepancy is probably attributed to the initial data heterogeneity and low statistical power. 相似文献
48.
Jos I. Labarta Michael B. Ranke Mohamad Maghnie David Martin Laura Guazzarotti Roland Pfffle Ekaterina Koledova Jan M. Wit 《Journal of clinical research in pediatric endocrinology》2021,13(2):124
Assessment and management of children with growth failure has improved greatly over recent years. However, there remains a strong potential for further improvements by using novel digital techniques. A panel of experts discussed developments in digitalization of a number of important tools used by pediatric endocrinologists at the third 360° European Meeting on Growth and Endocrine Disorders, funded by Merck KGaA, Germany, and this review is based on those discussions. It was reported that electronic monitoring and new algorithms have been devised that are providing more sensitive referral for short stature. In addition, computer programs have improved ways in which diagnoses are coded for use by various groups including healthcare providers and government health systems. Innovative cranial imaging techniques have been devised that are considered safer than using gadolinium contrast agents and are also more sensitive and accurate. Deep-learning neural networks are changing the way that bone age and bone health are assessed, which are more objective than standard methodologies. Models for prediction of growth response to growth hormone (GH) treatment are being improved by applying novel artificial intelligence methods that can identify non-linear and linear factors that relate to response, providing more accurate predictions. Determination and interpretation of insulin-like growth factor-1 (IGF-1) levels are becoming more standardized and consistent, for evaluation across different patient groups, and computer-learning models indicate that baseline IGF-1 standard deviation score is among the most important indicators of GH therapy response. While physicians involved in child growth and treatment of disorders resulting in growth failure need to be aware of, and keep abreast of, these latest developments, treatment decisions and management should continue to be based on clinical decisions. New digital technologies and advancements in the field should be aimed at improving clinical decisions, making greater standardization of assessment and facilitating patient-centered approaches. 相似文献
49.
Ekaterina S. Prokudina Boris K. Kurbatov Konstantin V. Zavadovsky Alexander V. Vrublevsky Natalia V. Naryzhnaya Yuri B. Lishmanov Leonid N. Maslov Peter R. Oeltgen 《Current Cardiology Reviews》2021,17(2):188
The purpose of the review is the analysis of clinical and experimental data on the etiology and pathogenesis of takotsubo syndrome (TS). TS is characterized by contractile dysfunction, which usually affects the apical region of the heart without obstruction of coronary artery, moderate increase in myocardial necrosis markers, prolonged QTc interval (in 50% of patients), sometimes elevation of ST segment (in 19% of patients), increase N-Terminal Pro-B-Type Natriuretic Peptide level, microvascular dysfunction, sometimes spasm of the epicardial coronary arteries (in 10% of patients), myocardial edema, and life-threatening ventricular arrhythmias (in 11% of patients). Stress cardiomyopathy is a rare disease, it is observed in 0.6 - 2.5% of patients with acute coronary syndrome. The occurrence of takotsubo syndrome is 9 times higher in women, who are aged 60-70 years old, than in men. The hospital mortality among patients with TS corresponds to 3.5% - 12%. Physical or emotional stress do not precede disease in all patients with TS. Most of patients with TS have neurological or mental illnesses. The level of catecholamines is increased in patients with TS, therefore, the occurrence of TS is associated with excessive activation of the adrenergic system. The negative inotropic effect of catecholamines is associated with the activation of β2 adrenergic receptors. An important role of the adrenergic system in the pathogenesis of TS is confirmed by studies which were performed using 125I-metaiodobenzylguanidine (125I -MIBG). TS causes edema and inflammation of the myocardium. The inflammatory response in TS is systemic. TS causes impaired coronary microcirculation and reduces coronary reserve. There is a reason to believe that an increase in blood viscosity may play an important role in the pathogenesis of microcirculatory dysfunction in patients with TS. Epicardial coronary artery spasm is not obligatory for the occurrence of TS. Cortisol, endothelin-1 and microRNAs are challengers for the role of TS triggers. A decrease in estrogen levels is a factor contributing to the onset of TS. The central nervous system appears to play an important role in the pathogenesis of TS. 相似文献
50.
Yulia
V. Lanchuk Sviatlana A. Ulasevich Tatiana A. Fedotova Dmitry M. Kolpashchikov Ekaterina V. Skorb 《RSC advances》2018,8(66):37735
Blind and color blind people cannot use colorimetric diagnostics; the problem is especially severe in rural areas where high temperatures and the absence of electricity challenge modern diagnostics. Here we propose to replace the unstable component of a diagnostic test, H2O2, with stable TiO2. Under UV irradiation, TiO2 forms reactive oxygen species that initiate polymerization of acrylamide causing liquid-to-gel transition in an analyte-dependent manner. We demonstrate that specific DNA sequences can be detected using this approach. This development may enable the detection of biological molecules by users with limited resources, for example in developing countries or for travelers in remote areas.Blind and color blind people cannot afford colorimetric diagnostics; the problem is especially severe in rural areas where high temperatures and the absence of electricity challenge modern diagnostics.An ideal diagnosis, including diagnosis for infectious diseases, should meet the ASSURED criteria: (i) affordable by those at risk of infection; (ii) sensitive; (iii) specific; (iv) user-friendly; (v) rapid, and robust, for example not requiring refrigerated storage; (vi) equipment-free; (vii) delivered to those who need it.1Analytic methods with visually detectable outputs (e.g. color change) satisfy criteria (iv) and (vi), and are therefore among the most common. Indeed, pregnancy tests, test strips for measuring acetone and glucose in urine for diabetic people, and pH strips are known to be the best to make the analysis easiest in data output. However, such methods cannot be used by the visually impaired.Recently, we described an alternative output signal that cannot only be detected by sight, but also by touch and applied it in the detection of adenosine triphosphate (ATP) and deoxyribonucleic acid (DNA).2 The method is based on the analyte-dependent radical polymerization of acrylamide into polyacrylamide in the presence of hydrogen peroxide (H2O2). H2O2 serves as a source of radicals. The test uses affordable reagents and does not require any instrumentation for signal readout. Such test systems can be adopted for detection of a wide variety of biological analytes. Unfortunately, H2O2 is subject to light decomposition and should be refrigerated for long term storage; it is also prone to exploding at high concentrations. Therefore, substituting H2O2 with a more stable ingredient would increase the shelf life of the test system and make it usable in those environments with limited access to refrigeration. This work is devoted to addressing the ASSURED criterion (v): we substituted perishable H2O2 with stable titania (TiO2) as an alternative source of initiators of radical polymerization.Recently we demonstrated the possibility of converting electromagnetic energy into pH gradients3 or generating reactive oxygen species (ROS) using TiO2,3,4 which makes this approach attractive for controlling interactions between chemical networks. Moreover, combining several functional chemical networks can result in a network with new functions. We have also shown that the pH gradient on titania can be used for regulating enzymatic reaction networks.5 In this work, we were interested in using photogenerated ROS (such as superoxide anion O2˙−, hydroxyl radical ˙OH, and hydrogen peroxide H2O2) (Fig. 1) to initiate radical polymerization with the aim of making a visual and tactile portable sensor for the detection of biologically important molecules (DNA, RNA, ATP). Under ultraviolet (UV) irradiation, TiO2 splits water, which results in the generation of a high concentration of ROS and free radicals.6Open in a separate windowFig. 1(i) A portable sensor based on a light-induced liquid-to-gel transition for polymer by radical polymerization on TiO2 particles. The details of the sensor design are shown in Fig. 5; (ii) ROS formation on titania via reactions with photogenerated photohole (h+) and photoelectron (e−).The sensing system is based on deoxyribozyme sensor that produces ROS in the presence of a specific analyte, thereby triggering the radical polymerization of acrylamide into polyacrylamide. The buffer contained acetylacetone, H2O2, 40% acrylamide/bisacrylamide, hemin and a split deoxyribozyme sensor with peroxidase-like activity (PxR).2 In the presence of the specific analyte sequence (A1 in this study), the sensor hybridized with the analyte and formed PxR, which bound hemin and decomposed H2O2 to ROS. The latter oxidized acetylacetone to the acetylacetone radical, which initiated the polymerization of acrylamide, resulting in liquid-to-gel conversion. Here, the aim of the research is to increase the system sustainability by changing H2O2 to TiO2 particles. Noteworthy is that the system is externally controlled by UV light, since TiO2 produces ROS only upon irradiation.Firstly, we quantified the TiO2-derived ROS with the aim of finding the optimal conditions for the generation of the minimum amount of ROS needed for the polymerization. We used luminol chemiluminescence (CL) calibrated with hydrogen peroxide. Luminol (5-amino-2,3-dihydro-1,4-phthalazinedione) is a widely used CL reagent and has CL emission at different wavelengths depending on the conditions.6 Traditionally, luminol CL is observed in the presence of H2O2 in alkaline solutions (Fig. 2), which is catalyzed by metal ions, metal complexes or vitamins.7–10Open in a separate windowFig. 2Mechanism of chemiluminescence of luminol and O2−˙.The luminol CL signaling is conveniently used for the detection of ROS (particularly superoxide anion, hydrogen peroxide, hydroxyl radical) in biological systems.11–16Irradiation of TiO2 suspensions of different concentrations (0.03 M and 0.06 M) at two wavelengths (365 nm and 254 nm) revealed more ROS being formed upon irradiation at 254 nm – as was expected (Fig. 3).Open in a separate windowFig. 3Log concentration of ROS generated in TiO2 suspensions of different concentration (0.03 M and 0.06 M) under irradiation by UV light with different wavelengths vs. irradiation time.According to the data obtained, the minimum concentration of TiO2 needed to trigger polymerization after 5 min of irradiation at 365 nm was 1.25 mM (Fig. 4). We therefore used these conditions in the following experiments, since short irradiation time and longer wavelength of UV-A irradiation are less damaging to the DNA-based biosensor component than UV-C light with wavelength of 254 nm. It should be noted that control experiments were made without TiO2 particles and polymerization did not occur. Next, we optimized the conditions for the analyte-dependent activation of PxR resulting in acrylamide polymerization. If polymerization occurs, the gel will stick to the bottom of the inverted tubes (Fig. 5).2 To demonstrate the general applicability of the approach, we designed a sensor for an analyte of biomedical significance, nucleic acids, as an example. A sequence of 16S rRNA, which was represented in this study by synthetic A1 sequence (5′-CAT TAC TCA CCC GTC CGC CAC TCG TCA GCG AAG CAG CAA GCT GCT TCC TGT TAC CGT TCG), of pathogenic E. coli O157:H7 was chosen as the target analyte,. The binding of A1 to PxR1 and PxR2 stabilized the G-quadruplex structure, which then binds to hemin and catalyzes the polymerization (Fig. 5A).Open in a separate windowFig. 4The dependence of the log concentration of ROS generated on TiO2 particles on TiO2 suspension concentration. Inserts show the minimum concentration of TiO2 particles in a suspension (therefore minimum concentration of ROS generated on TiO2 particles), needed for the gel formation.Open in a separate windowFig. 5Polymerization-based visual and tactile detection of A1 analyte. (A) Sensor design: RNA strands PxR1 and PxR2 bind A1 sequence and form a G-quadruplex structure, which then binds to hemin (green oval) and catalyzes the radical polymerization of the acrylamide solution. The dotted lines represent triethylene glycol linkers. (B and C) Inverted test-tubes with radical polymerization of acrylamide initiated by reactive oxygen species generated on TiO2 particles under UV light 365 nm. (B) Systems with different concentrations of hemin (No. 1 2 3 4 5 6 C, M 10−9 2.5 × 10−8 5 × 10−8 7.5 × 10−8 10−7 2.5 × 10−7 Gel − − − + + +