全文获取类型
收费全文 | 492篇 |
免费 | 30篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 14篇 |
妇产科学 | 13篇 |
基础医学 | 56篇 |
口腔科学 | 17篇 |
临床医学 | 48篇 |
内科学 | 106篇 |
皮肤病学 | 10篇 |
神经病学 | 23篇 |
特种医学 | 12篇 |
外科学 | 63篇 |
综合类 | 7篇 |
预防医学 | 44篇 |
眼科学 | 8篇 |
药学 | 49篇 |
中国医学 | 5篇 |
肿瘤学 | 46篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 40篇 |
2020年 | 20篇 |
2019年 | 36篇 |
2018年 | 36篇 |
2017年 | 28篇 |
2016年 | 26篇 |
2015年 | 21篇 |
2014年 | 26篇 |
2013年 | 30篇 |
2012年 | 43篇 |
2011年 | 38篇 |
2010年 | 26篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 26篇 |
2006年 | 18篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
排序方式: 共有524条查询结果,搜索用时 62 毫秒
51.
Ilnaz Sahragard Yahya Tahamtan Majid Valadan Masoumeh Hyati Farid Moazeni Zahra Shirazi 《Comparative clinical pathology》2012,21(6):1333-1336
Toxigenicity, species, and type species of Pasteurella multocida isolates cannot be differentiated by morphology or standard biochemical reactions. A more rapid method is needed for P. multocida detection from clinical cases. These findings provide rapid insights into the characteristics of P. multocida isolates and suggest that this method can identify toxigenic and specific capsular type P. multocida. A PCR assay has been developed for rapid detection of P. multocida and differentiation of capsular types A and D. In this rapid method, kmt1, capA and capD, and toxA genes were amplified and a reliable multiplex PCR method for the detection of P. multocida in sheep and goats in the south of Iran was designed. Twenty isolates were obtained, which evinced characteristic morphological and cultural properties. Ten samples were identified simultaneously through the presence of the kmt1 gene as P. multocida species, the hydD–hydC gene as type A capsule, and the toxA gene as dermonecrotic toxin by mPCR, but none of them belonged to type D. 相似文献
52.
53.
54.
Hakimeh Sadeghian M.D. Farzaneh Ahmadi M.D. Masoumeh Lotfi‐Tokaldany M.D. Rezvanyieh Salehi M.D. Reyhane Zavar M.D. Mahmood Sheikh Fathollahi Seyed Hesameddin Abbasi M.D. 《Echocardiography (Mount Kisco, N.Y.)》2010,27(7):803-808
Background: Longitudinal myocardial tissue velocity imaging (TVI) and strain rate imaging (SRI) quantify regional myocardial function. We aimed to measure TVI and SRI indices for inferobasal aneurysmal segments by echocardiography at rest. Method: Sixteen patients with inferobasal left ventricular (LV) aneurysm, LV ejection fraction (EF) ≤50%, and 14 normal coronaries with normal echocardiography (control group) were studied. In SRI, peak systolic strain (ST), strain rate (SR), and pattern of strain curves and in TVI, peak systolic inward motion (Sm) were evaluated all at rest. Ascending curve means systolic expansion and descending means shortening. Results: LVEF was significantly lower in the patient group. Mean ST, SR, and Sm of inferobasal segment showed significant difference between patient and control groups; for ST: 1.45 ± 7.18% versus ?17.64 ± 7.45%, P < 0.0001; SR: ?0.25 ± 0.26 versus ?1.44 ± 0.64 sec?1, P < 0.0001; and Sm: 3.85 ± 1.26 versus 5.56 ± 1.28 cm/sec, P = 0.006, respectively. All inferobasal aneurysmal segments had ascending curve while normal segments showed a descending curve. In patient group, aneurysmal segments had significantly reduced ST and SR compared to normal segments. Normal functioning segments of patients showed significant reduction of ST and SR compared to normal LV segments in control subjects. The range of SR and ST for inferobasal aneurysmal segments did not overlap with that of the normal segments (?0.60, 0.19 and ?3.00, ?0.80 sec?1 for SR, and ?8.30, 23.30 and ?35.30, ?10.00% for ST, respectively). Conclusion: SRI indices were significantly reduced in inferobasal aneurysmal segment in comparison with either the same segment in normal subjects or normal functioning segments in the same patients. SR and ST may be superior to Sm in the evaluation of inferobasal aneurysmal segments. (Echocardiography 2010;27:803‐808) 相似文献
55.
Sarraf-Zadegan N Sadri G Malek Afzali H Baghaei M Mohammadi Fard N Shahrokhi S Tolooie H Poormoghaddas M Sadeghi M Tavassoli A Rafiei M Kelishadi R Rabiei K Bashardoost N Boshtam M Asgary S Naderi G Changiz T Yousefie A 《Acta cardiologica》2003,58(4):309-320
The Isfahan Healthy Heart Programme (IHHP) is a five to six year comprehensive integrated community-based programme for cardiovascular diseases (CVD) prevention and control via reducing CVD risk factors and improvement of cardiovascular healthy behaviour in a target population. IHHP started late in 1999 and will be finished in 2005-2006. A primary survey was done to collect baseline data from interventional (Isfahan and Najaf-Abad) and reference (Arak) communities. In a two-stage sampling method, we randomly selected 5 to 10 percent of households from randomly selected clusters. Then individuals aged > or = 19 years were selected for the survey. This way, data from 12,600 individuals (6300 in interventional counties and 6300 in the reference county) was collected and stratified according to living area (urban vs. rural) and different age and sex groups. The samples underwent a 30-minute interview to complete validated questionnaires containing questions on demography, socioeconomic status, smoking behaviour, physical activity, nutritional habits and other behaviour regarding CVD. Blood pressure and body mass index (BMI) measurements were done and fasting blood samples were taken for two hours post load plasma glucose (2 hpp), serum (total, HDL and LDL) cholesterol and triglyceride levels. A twelve-lead electrocardiogram was recorded in all persons above 35 years of age. Community-wide surveillance of deaths, hospital discharges, myocardial infarction and stroke registry was carried out in the intervention and control areas. Four to five years of interventions based on different categories such as mass media, community partnerships, health system involvement and policy and legislation have started in the intervention area while Arak will be followed without intervention. Considering the results of the baseline surveys, (assessments needed, the objectives, existing resources and the possibility of national implementation) the interventions were planned. They were set based on specific target groups like school children, women, work-site, health personnel, high-risk persons, and community leaders were actively engaged as decision makers. A series of teams was arranged for planning and implementation of the intervention strategies. Monitoring will be done on small samples to assess the effect of different interventions in the intervention area. While four periodic surveys will be conducted on independent samples to assess health behaviours related to CVD risk factors in the intervention and reference areas, the original pre-intervention subjects aged more than 35 years will be followed in both areas to assess the individual effect of interventions and outcomes like sudden death, fatal and nonfatal MI and stroke. The whole baseline survey will be repeated on the original and an independent sample in both communities at the end of the study. 相似文献
56.
Shervin Ghaffari Hoseini Kiyan HeshmatGhahdarijani Saeid Khosrawi Mohammad Garakyaraghi Davood Shafie Hamidreza Roohafza Marjan Mansourian Elham Azizi Yousof Gheisari Masoumeh Sadeghi 《Clinical cardiology》2021,44(9):1263
BackgroundThis study aimed to investigate the effect of melatonin supplementation on endothelial function in patients with heart failure with reduced ejection fraction (HFrEF).MethodsThis is an analysis of the MeHR trial, a randomized double‐blinded placebo‐controlled clinical trial with two parallel arms of 1:1. Oral 10 mg melatonin tablets or placebo was administered for 24 weeks. Deference in the percentage of flow‐mediated dilatation (FMD) after the intervention was the primary outcome.ResultsNinety‐two patients were included in the study (age: 62.7±10.3 years, 87.0% male, ejection fraction (EF): 28.6±8.1). After adjustment for baseline FMD and age, a statistically significant difference in post‐treatment FMD in favor of the melatonin group was seen (estimated marginal means [95%CI], melatonin: 7.84% [6.69–8.98], placebo: 5.98% [4.84–7.12], p = .027). There was no significant difference in the mean of post‐treatment systolic/diastolic blood pressure, serum total antioxidant capacity, and serum malondialdehyde (MDA) between groups. Subgroup analysis showed significant improvement in FMD and MDA in the melatonin group in nondiabetic patients, while no difference was seen between study groups in diabetic patients.ConclusionsMelatonin supplementation in HFrEF might improve endothelial function; however, this beneficial effect might not be seen in diabetic patients. 相似文献
57.
Alieh Daryabor Mohammad Samadian Masoumeh Veiskarami Monireh Ahmadi Bani 《Disability and rehabilitation. Assistive technology》2017,12(4):324-332
Background: Adolescent idiopathic scoliosis (AIS) is a progressive growth disease that affects spinal anatomy, mobility, and left-right trunk symmetry. As a consequence, AIS can modify human gait. Spinal orthoses are a commonly used conservative method for the treatment of AIS.Objective: This review evaluated the AIS spinal orthosis literature that involved gait and energy consumption evaluations.Study design: Literature review.Method: According to the population intervention comparison outcome measure methods and based on selected keywords, 10 studies met the inclusion criteria.Results: People with AIS who wore a spinal orthosis, compared with able-bodied participants, walked slower with decreased hip and pelvic movements, decreased hip mediolateral forces, ground reaction force asymmetry, and excessive energy cost. Pelvis and hip frontal plane motion decreased when wearing an orthosis. Hip and pelvis movement symmetry improved when using an orthosis. Ankle and foot kinematics did not change with orthotic intervention. People with AIS continued to have excessive energy expenditure with an orthosis.Conclusion: Spinal orthoses may be considered for improving the walking style, although energy cost does not decline following the orthotic intervention.
- Implications for Rehabilitations
Problems related to scoliosis include reduced quality of life, disability, pain, postural alterations, sensory perturbations, standing instability and gait modifications.
Wearing corrective spinal orthoses in AIS subjects produce a reduction in walking speed and cadence, increase in stride length and reduction of gait load asymmetry compared to without brace condition.
Spinal orthoses do not decline excessive energy expenditure to walk versus without it.
58.
Julia J. Griese Katarina Roos Nicholas Cox Hannah S. Shafaat Rui M. M. Branca Janne Lehti? Astrid Gr?slund Wolfgang Lubitz Per E. M. Siegbahn Martin H?gbom 《Proceedings of the National Academy of Sciences of the United States of America》2013,110(43):17189-17194
Although metallocofactors are ubiquitous in enzyme catalysis, how metal binding specificity arises remains poorly understood, especially in the case of metals with similar primary ligand preferences such as manganese and iron. The biochemical selection of manganese over iron presents a particularly intricate problem because manganese is generally present in cells at a lower concentration than iron, while also having a lower predicted complex stability according to the Irving–Williams series (MnII < FeII < NiII < CoII < CuII > ZnII). Here we show that a heterodinuclear Mn/Fe cofactor with the same primary protein ligands in both metal sites self-assembles from MnII and FeII in vitro, thus diverging from the Irving–Williams series without requiring auxiliary factors such as metallochaperones. Crystallographic, spectroscopic, and computational data demonstrate that one of the two metal sites preferentially binds FeII over MnII as expected, whereas the other site is nonspecific, binding equal amounts of both metals in the absence of oxygen. Oxygen exposure results in further accumulation of the Mn/Fe cofactor, indicating that cofactor assembly is at least a two-step process governed by both the intrinsic metal specificity of the protein scaffold and additional effects exerted during oxygen binding or activation. We further show that the mixed-metal cofactor catalyzes a two-electron oxidation of the protein scaffold, yielding a tyrosine–valine ether cross-link. Theoretical modeling of the reaction by density functional theory suggests a multistep mechanism including a valyl radical intermediate.Half of all enzymes are estimated to contain metallocofactors (1). An important subset uses transition metal ions to perform key redox reactions such as oxygen activation. The diiron cofactor of the ferritin-like superfamily of proteins is particularly versatile (2). While ferritin itself simply oxidizes and sequesters iron (3), in other family members the diiron center acts as a transient one- or two-electron oxidant. In the R2 subunits of class I ribonucleotide reductases (RNRs) it generates a redox-active tyrosyl radical (4, 5), whereas in the bacterial multicomponent monooxygenases (BMMs) it catalyzes the hydroxylation of a variety of hydrocarbons (6). For four decades it was assumed that all ferritin superfamily proteins contained diiron cofactors. However, in recent years new subfamilies harboring either a dimanganese or heterodinuclear Mn/Fe cofactor have been documented (7–14). The Mn/Fe cofactor was discovered in class Ic RNR R2 subunits, where its MnIV/FeIII state functionally replaces the diiron-tyrosyl radical cofactor of class Ia R2s (9, 10). After a long controversy, class Ib R2 proteins were shown to use a dimanganese cofactor in the same scaffold (7, 8). These recent developments highlight the complexity of correctly identifying the metals that make up native metallocofactors. While the metal preferences of some primary coordination motifs are well known and distinct, others are more promiscuous and less well understood. Manganese and iron are two of the most important and versatile metals for biological redox chemistry. Their primary ligand preferences are very similar, and their binding sites in enzymes often appear virtually identical (15). However, their redox potentials differ greatly, and correct discrimination between them is therefore paramount for redox-active enzymes (16). Metal specificity is commonly discussed in terms of the intracellular availability of metal ions and the Irving–Williams series of metal complex stabilities (MnII < FeII < NiII < CoII < CuII > ZnII) (17). Manganese is generally present in cells at a lower concentration than iron (18) and also has a lower predicted complex stability. The biochemical selection of manganese over iron thus presents an intricate problem. Metallochaperones are required for correct metallation of some metalloproteins (19–22), but to date no chaperones have been identified for manganese, and it is unclear whether they are required for diiron clusters (16). Protein-folding location or general metal status can also control metallation (16, 23). However, these mechanisms cannot be used for proteins with mixed-metal cofactors.The heterodinuclear Mn/Fe cofactor recently discovered in a protein from Mycobacterium tuberculosis provides an ideal model system to study manganese/iron metallation. The protein was found to belong to a novel group of R2-like proteins, denoted R2-like ligand-binding oxidases (R2lox) (11, 24). These proteins are particularly interesting because the primary protein-derived metal-binding ligands are identical in both metal sites, and also identical to the closely related diiron-binding BMMs. To verify that the mixed-metal cofactor is a common feature of the R2lox group, here we characterize a homolog from the thermophilic bacterium Geobacillus kaustophilus (GkR2loxI). Using crystallography, spectroscopy, and quantum chemical calculations, we show that site-specific metal discrimination is inherent to the protein structure and diverges from the Irving–Williams series without requiring auxiliary factors in vitro. The mixed-metal cofactor activates oxygen and catalyzes the formation of an ether cross-link in the protein scaffold, demonstrating the chemical potential of this cofactor. 相似文献
59.
Novel hydrophobic cellulose aerogel (CA) supported graphene quantum dots (GQD)/Pd were synthesized with high lipophilicity, superior porosity as well as high catalytic activity. The nanocomposite aerogel was obtained in four steps, including transformation of cotton to CA, a silanization reaction of CA in the presence of TiO2 nanoparticles to give polysiloxane/TiO2 nanoparticles supported on CA (ST@CA), a modification of ST@CA with GQD to yield polysiloxane/TiO2 nanoparticles/graphene quantum dots supported on CA (STG@CA), and finally a deposition of Pd nanoparticles on STG@CA. The synthesized aerogel demonstrated hydrophobicity with a water contact angle of 136.2°. It also exhibited excellent oil/water selective absorption capacity with an oil absorption of up to 79 g g−1 with 134 g g−1 selectivity. Finally, the nanocomposite was used as a heterogeneous catalyst in the oxidation reaction of alcohols, ethylbenzene, and alkenes. High yields, excellent selectivities, green and mild reaction conditions, recyclability and biocompatibility of the catalyst were important features of the reactions.Novel hydrophobic cellulose aerogel (CA) supported graphene quantum dots (GQD)/Pd were synthesized with high lipophilicity, superior porosity as well as high catalytic activity. 相似文献
60.
Sharif-Alhoseini M Saadat S Rahimi-Movaghar A Motevalian A Amin-Esmaeili M Hefazi M Rahimi-Movaghar V 《中华创伤杂志(英文版)》2012,15(3):145-147
Objective: Injury is a major cause of morbidity and mortality in the world.The assessment of patterns and severity of injury in high-risk groups is crucial for planning and service development.On a lar... 相似文献