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   1053篇
  免费   70篇
  国内免费   4篇
耳鼻咽喉   6篇
儿科学   42篇
妇产科学   8篇
基础医学   167篇
口腔科学   25篇
临床医学   102篇
内科学   233篇
皮肤病学   15篇
神经病学   72篇
特种医学   20篇
外科学   180篇
综合类   33篇
预防医学   71篇
眼科学   22篇
药学   67篇
中国医学   15篇
肿瘤学   49篇
  2024年   4篇
  2023年   12篇
  2022年   38篇
  2021年   66篇
  2020年   26篇
  2019年   40篇
  2018年   41篇
  2017年   30篇
  2016年   42篇
  2015年   32篇
  2014年   45篇
  2013年   74篇
  2012年   53篇
  2011年   74篇
  2010年   49篇
  2009年   30篇
  2008年   73篇
  2007年   62篇
  2006年   65篇
  2005年   55篇
  2004年   68篇
  2003年   48篇
  2002年   36篇
  2001年   15篇
  2000年   11篇
  1999年   7篇
  1998年   7篇
  1997年   2篇
  1996年   4篇
  1995年   1篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   4篇
  1989年   1篇
  1987年   1篇
  1986年   2篇
  1982年   1篇
  1978年   1篇
  1967年   1篇
排序方式: 共有1127条查询结果,搜索用时 250 毫秒
51.
Imam  Mohamed  Shehata  Mohamed  Morsi  Mahmoud  Shawqi  Muhammad  Elsehili  Ahmed  Trikha  Paul  Ernstbrunner  Lukas  Unnithan  Ashwin  Khaleel  Arshad  Monga  Puneet  Narvani  Ali  Sallam  Asser 《HSS journal》2020,16(3):222-232
HSS Journal ® - Hip hemiarthroplasty is a well-established treatment of displaced femoral neck fracture, although debate exists over whether cemented or uncemented fixation is superior....  相似文献   
52.
53.
Synthesis of zeolite T with a variety of desired characteristics necessitates extensive work in formulation and practical experiments, either by conventional hydrothermal methods or aided with different approaches and synthesis techniques, such as secondary growth or microwave irradiation. The objectives of this review are to adduce the potential work in zeolite T (Offretite-Erionite) synthesis, evaluating determining factors affecting the synthesis and quality of zeolite T crystals. Attention is given to extensive studies that interconnect with other significant findings.  相似文献   
54.
In recent years, research and development of geopolymers has gained significant interest in the fields of repairs and restoration. This paper investigates the application of a geopolymer as a repair material by implementation of high-calcium fly ash (FA) as a main precursor, activated by a sodium hydroxide and sodium silicate solution. Three methods of concrete substrate surface preparation were cast and patched: as-cast against ordinary Portland cement concrete (OPCC), with drilled holes, wire-brushed, and left as-cast against the OPCC grade 30. This study indicated that FA-based geopolymer repair materials (GRMs) possessed very high bonding strength at early stages and that the behavior was not affected significantly by high surface treatment roughness. In addition, the investigations using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy have revealed that the geopolymer repair material became chemically bonded to the OPC concrete substrate, due to the formation of a C–A–S–H gel. Fundamentally, the geopolymer network is composed of tetrahedral anions (SiO4)4− and (AlO4)5− sharing the oxygen, which requires positive ions such as Na+, K+, Li+, Ca2+, Na+, Ba2+, NH4+, and H3O+. The availability of calcium hydroxide (Ca(OH)2) at the surface of the OPCC substrate, which was rich in calcium ions (Ca2+), reacted with the geopolymer; this compensated the electron vacancies of the framework cavities at the bonding zone between the GRM and the OPCC substrate.  相似文献   
55.

Background:

Soft-tissue defects around the knees are common in injured limbs and in the same injury the leg is often involved and the thigh is spared. Furthermore due to pliable and relatively lax skin, we have used inferiorly based thigh flap to reconstruct defects around knee joint.

Aims and Objectives:

The aim of this study is to evaluate the use of inferiorly based thigh flap to cover soft-tissue defects over the proximal one-third of the leg, patellar region, knee, and lower thigh.

Materials and Methods:

This study was conducted during the period between October 2011 and February 2013. Inferiorly based anteromedial thigh fasciocutaneous flap was performed on 12 patients and inferiorly based anterolateral thigh fasciocutaneous flap on four patients. The sites of the soft-tissue defects included patellar regions, infrapatellar region, upper one-third of leg, lower thigh, and over the knee joint.

Results:

Patients were evaluated post-operatively in terms of viability of flap, the matching of the flap with the recipient site, and donor site morbidity. All the flaps survived well except one which developed distal marginal flap loss, one in which wound dehiscence was noticed, and two in which mild venous congestion was observed. Venous congestion in two patients subsided on its own within 3 days. One patient with wound dehiscence achieved complete healing by secondary intention. Patient who developed distal flap loss required debridement and skin grafting. No appreciable donor site morbidity was encountered. Skin colour and texture of the flap matched well with the recipient site.

Conclusions:

The inferiorly based thigh flap is a reliable flap to cover the defect over proximal one-third of the leg, patellar region, knee, and lower thigh.KEY WORDS: Defect around the knee joint, inferiorly based thigh flap, perforator based flap  相似文献   
56.
In this study, noble ligands of (E)-N′-(benzo[d]dioxol-5-ylmethylene)-4-methyl-benzenesulfonohydrazide (BDMMBSH) were prepared via a simple condensation method using benzo-[d][1,3]-dioxole carbaldehyde, benzenesulfonylhydrazine (BSH), and 4-methyl-benzenesulphonylhydrazine (4-MBSH) in good yield, which were crystallized in acetone, EtOAc, and EtOH. The BDMMBSH derivatives were characterized using different spectroscopic techniques, such as 1H-NMR, 13C-NMR, FTIR, and UV-Vis spectroscopy, and their crystal structures were analyzed using the single crystal X-ray diffraction method (SCXRDM). Subsequently, the BDMMBSH compounds were used for the significant detection of the carcinogenic heavy metal ion, lead (Pb2+), via a reliable electrochemical approach. A sensitive and selective Pb2+ sensor was developed via the deposition of a thin layer of BDMMBSH on a GCE with the conducting polymer matrix Nafion (NF). The sensitivity, LOQ, and LOD of the proposed sensor towards Pb2+ were calculated from the calibration curves to be 2220.0 pA μM−1 cm−2, 320.0 mM, and 96.0 pM, respectively. The validation of the BDMMBSH/GCE/NF sensor probe was performed via the selective determination of Pb2+ in spiked natural samples with a satisfactory and rational outcome.

A sensitive cationic sensor was developed by BDMMBSH onto GCE with 5% Nafion using electrochemical method, which was validated with the selective determination of Pb2+ in spiked samples and found satisfactory results.  相似文献   
57.
58.
BACKGROUND: Tumour necrosis factor alpha (TNFalpha) is a major therapeutic target in a range of chronic inflammatory disorders characterised by a Th1 type immune response in which TNFalpha is generated in excess. By contrast, asthma is regarded as a Th2 type disorder, especially when associated with atopy. However, as asthma becomes more severe and chronic, it adopts additional characteristics including corticosteroid refractoriness and involvement of neutrophils suggestive of an altered inflammatory profile towards a Th1 type response, incriminating cytokines such as TNFalpha. METHODS: TNFalpha levels in bronchoalveolar lavage (BAL) fluid of 26 healthy controls, 42 subjects with mild asthma and 20 with severe asthma were measured by immunoassay, and TNFalpha gene expression was determined in endobronchial biopsy specimens from 14 patients with mild asthma and 14 with severe asthma. The cellular localisation of TNFalpha was assessed by immunohistochemistry. An open label uncontrolled clinical study was then undertaken in 17 subjects with severe asthma to evaluate the effect of 12 weeks of treatment with the soluble TNFalpha receptor-IgG1Fc fusion protein, etanercept. RESULTS: TNFalpha levels in BAL fluid, TNFalpha gene expression and TNFalpha immunoreative cells were increased in subjects with severe corticosteroid dependent asthma. Etanercept treatment was associated with improvement in asthma symptoms, lung function, and bronchial hyperresponsiveness. CONCLUSIONS: These findings may be of clinical significance in identifying TNFalpha as a new therapeutic target in subjects with severe asthma. The effects of anti-TNF treatment now require confirmation in placebo controlled studies.  相似文献   
59.
Membrane fouling is a major hindrance to widespread wastewater treatment applications. This study optimizes operating parameters in membrane rotating biological contactors (MRBC) for maximized membrane fouling through Response Surface Methodology (RSM) and an Artificial Neural Network (ANN). MRBC is an integrated system, embracing membrane filtration and conventional rotating biological contactor in one individual bioreactor. The filtration performance was optimized by exploiting the three parameters of disk rotational speed, membrane-to-disk gap, and organic loading rate. The results showed that both the RSM and ANN models were in good agreement with the experimental data and the modelled equation. The overall R2 value was 0.9982 for the proposed network using ANN, higher than the RSM value (0.9762). The RSM model demonstrated the optimum operating parameter values of a 44 rpm disk rotational speed, a 1.07 membrane-to-disk gap, and a 10.2 g COD/m2 d organic loading rate. The optimization of process parameters can eliminate unnecessary steps and automate steps in the process to save time, reduce errors and avoid duplicate work. This work demonstrates the effective use of statistical modeling to enhance MRBC system performance to obtain a sustainable and energy-efficient treatment process to prevent human health and the environment.  相似文献   
60.

Background  

Intellectual disability (ID) is a serious disorder of the central nervous system with a prevalence of 1-3% in a general population. In the past decades, the research focus has been predominantly on X-linked ID (68 loci and 19 genes for non syndromic X linked ID) while for autosomal recessive nonsyndromic ID (NSID) only 30 loci and 6 genes have been reported to date.  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