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   12837篇
  免费   970篇
  国内免费   778篇
耳鼻咽喉   15篇
儿科学   48篇
妇产科学   24篇
基础医学   981篇
口腔科学   255篇
临床医学   1338篇
内科学   187篇
皮肤病学   15篇
神经病学   517篇
特种医学   806篇
外科学   5156篇
综合类   2312篇
现状与发展   1篇
预防医学   289篇
眼科学   496篇
药学   646篇
  15篇
中国医学   1362篇
肿瘤学   122篇
  2024年   263篇
  2023年   290篇
  2022年   427篇
  2021年   499篇
  2020年   490篇
  2019年   354篇
  2018年   397篇
  2017年   425篇
  2016年   448篇
  2015年   477篇
  2014年   1072篇
  2013年   948篇
  2012年   904篇
  2011年   943篇
  2010年   823篇
  2009年   664篇
  2008年   582篇
  2007年   598篇
  2006年   533篇
  2005年   444篇
  2004年   403篇
  2003年   404篇
  2002年   337篇
  2001年   267篇
  2000年   210篇
  1999年   223篇
  1998年   152篇
  1997年   138篇
  1996年   128篇
  1995年   107篇
  1994年   101篇
  1993年   85篇
  1992年   65篇
  1991年   54篇
  1990年   22篇
  1989年   49篇
  1988年   25篇
  1987年   30篇
  1986年   36篇
  1985年   26篇
  1984年   25篇
  1983年   12篇
  1982年   29篇
  1981年   16篇
  1980年   6篇
  1979年   13篇
  1978年   10篇
  1977年   14篇
  1976年   3篇
  1973年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Neuro-Chirurgie》2021,67(6):624-627
BackgroundSpinal cord herniation (SCH) remains a challenging diagnosis for neuroradiologists and may require treatment challenging for neurosurgeons. Most cord herniations are usually found at anterior thoracic levels.Clinical presentationA 28-year-old woman presented at our department with a 7-year history of progressive myelopathy. MR analysis showed a displacement of the spinal cord in a lateral thoracic dural defect. The herniated cord was released using a microscope and the patient significantly recovered 6 months after surgery.ConclusionWe present a unique case of pure lateral SCH. In the light of reviewed literature and operative findings, the underlying pathophysiological mechanisms are discussed.  相似文献   
2.
Background/ObjectiveOccurrence of post-dural puncture headache (PDPH) after diagnostic lumbar puncture (LP) for idiopathic intracranial hypertension (IIH) may seem very unlikely in clinical practice. Nevertheless, it has been suggested by several studies, mainly in sub-group analyses. We aimed to evaluate the prevalence of PDPH in an IIH population and determine any eventual predictive factors of PDPH occurrence.MethodsWe conducted a retrospective multiple-center observational study. All newly diagnosed IIH patients who met the International Classification of Headache Disorders (ICHD-3) or the Dandy modified criteria were included from three different French hospitals. They all underwent LP following the same process with the same type of needle. We recorded PDPH occurring within five days after LP, as defined by ICHD-3 criteria.ResultsSeventy-four IIH patients were recruited, of whom 23 (31%) presented with PDPH. Neither classical risk factors for PDPH such as body mass index, age or gender, nor cerebrospinal fluid opening pressure, or specific IIH features were associated with occurrence of PDPH.ConclusionPDPH can occur after LP in IIH patients. Clinicians should be aware of this possible event during the IIH diagnosis assessment and should not automatically reconsider IIH diagnosis. PDPH prevention using an atraumatic needle and dedicated PDPH treatment seem relevant in IIH patients.  相似文献   
3.
This study was designed to evaluate the influence of prolonged tensile stress on the viscoelasticity of the temporomandibular joint (TMJ) disc. Twenty discs from 10, 3-year-old cattle were used. Tensile stress of 1.5 MPa was applied to specimens from the discs for 10, 20, 40 and 60 min. Following the prescribed period of tension for creep, the specimens were removed from the tension device and any recovery observed for 20 min. In all specimens, strain increased at the onset of stress application and reached almost steady conditions after 5 min. Although, the strain became slightly larger when the creep time was longer, no significant differences were found in the strains between any two tests with different periods of creep. The residual strain increased significantly with creep duration, and similarly the degree of recovery decreased significantly. In 10- and 20-min creep tests, the residual strains were 0.1 and 1.0%, the specimens in 40- and 60-min tests revealed irreversible changes in length. It was concluded that continuous loading for >40 min causes creep damage in bovine TMJ disc, and that prolonged sustained tension affects the recovery of joint homeostasis.  相似文献   
4.
The mechanism of oxygen reduction on the as-polished and corroded zinc specimens has been studied using a rotating ring disc electrode (RRDE) system. On the as-polished surface, oxygen was reduced into two distinct steps. In the first step, about 44% of O2 was reduced to H2O2 in a 2-electron reaction with the rest being reduced to OH? in a 4-electron reaction. On the other hand, in the second step, with the increase of overpotential O2 was almost exclusively reduced to OH? in a 4-electron reaction. The first step reduction occurred on an air-formed oxide-covered surface at more positive potential than ?1.2 V vs. Ag/AgCl and the second step reduction (E < ?1.2 V) took place on a semi-uniformly active surface. On the corroded surface, the second step was not distinctly observed on the polarization curve, because reduction of the zinc corrosion products simultaneously took place around ?1.2 V. The O2 reduction in the first step was inhibited by deposition of the corrosion products, though the ratio of amount of O2 reduced to OH? in a 4-electron reaction was larger than that on the as-polished surface. The mechanism of oxygen reduction is discussed on the basis of results obtained from the RRDE experiment.  相似文献   
5.
目的 用透射电镜的方法对两只1月龄健康山羊四只颞下颌关节盘的细胞及胶原结构进行了观察.方法 切取山羊双侧颞下颌关节盘,经组织学处理后行透射电镜观察细胞和胶原超微结构特征.结果 颞下颌关节盘由不均分布的细胞和胶原纤维组成,细胞有成纤维细胞样细胞和软骨细胞样细胞两种,其中成纤维细胞样细胞较软骨细胞样细胞占优势.成纤维细胞样细胞表现有细长的突起,核大,梭形或不规则形,细胞器较少.软骨细胞样细胞胞核呈圆形或椭圆形,周围少有电子透射区,细胞膜不明显,胞突少见.胶原纤维由平行排列的有周期性横纹特征的胶原原纤维组成.结论 颞下颌关节盘细胞有成纤维细胞样和软骨细胞样细胞两种,前者占优势,胶原原纤维表现有周期性横纹特征.这为颞下颌关节盘组织工程研究中细胞来源及表型分析奠定了一定基础.  相似文献   
6.
颞下颌关节盘前移位后关节组织中S-100的表达   总被引:1,自引:0,他引:1  
目的:探讨颞下颌关节盘前移位后关节组织中S-100表达的变化及其意义。方法:26只日本大耳白兔,在建立颞下颌关节盘前移位动物模型后,分别于术后1周、2周、4周、6周、8周、10周和12周处死,用免疫组织化学方法检测关节组织内S-100的分布。结果:正常时S-100的表达主要位于关节盘前带和后带的软骨细胞中,双板区内无软骨细胞亦无S-100的表达。1周时下板内有少量成纤维细胞和纤维软骨细胞弱表达S-100,2周时出现少量弱表达S-100的游离软骨细胞。以后软骨细胞数目逐渐增多、S-100表达逐渐增强。10周时,可见多数强表达S-100的软骨细胞,12周时,滑膜层亦可见软骨细胞的出现及S-100的表达。结论:关节盘前移位后双板区出现软骨细胞及S-100的表达,S-100的表达可能与双板区组织的适应性改建有关。  相似文献   
7.
It is of clinical interest to record the amplitudes of temporomandibular joint (TMJ) sounds. The aim was to test the hypothesis that sealing the meatus, when placing a microphone in the ear canal affects such recording by increasing the sound pressure level (SPL). Bilateral recordings of 249 TMJ clickings were made from three subjects, using sampling rates of 48 or 96 kHz and 24 bits A/D conversion, with and without the ear canals sealed by Silicone putty. The peak-to-peak equivalent sound pressure level (peSPL) was higher (P < 0.001) when the ear canal was sealed (range of mean differences was 8.3-24.9 dB peSPL). This means that the signal to noise ratio can be improved by sealing the meatus because the electronic noise level is not increased. Most important is that the dynamic range of the clicking sounds was 62 dB that is larger than the effective dynamic range of a 16 bits sound card. Future studies are needed to establish normative peSPL values. However, cards with at least 24 bits A/D conversion will be required, especially in patients with suspected disc displacement with reduction, where the difference in loudness between opening and closing clicking often is large.  相似文献   
8.
The purpose of this study was to determine whether 12.5 MHz ultrasonography (US) could be used to assess the presence or absence of temporomandibular joint (TMJ) internal derangement (ID). In 48 consecutive patients with TMJ disorders 192 TMJ positions were investigated by US to analyse the functional disc-condyle relationship (DCR). In order to compare the respective findings with those of a diagnostic method offering a high accuracy, coronal and sagittal magnetic resonance imaging was carried out immediately afterwards. With US showing a sensitivity of 0.58 and 0.75, and a specificity of 0.92 and 0.84 for disc displacement with and without reduction, the data revealed US to be marginal in detecting the presence, but sensitive in detecting the absence of the respective types of a TMJ ID. In addition, with a positive predictive value of 0.83 and 0.71, and a negative predictive value of 0.81 and 0.87 for disc displacement with and without reduction, the results indicate that US may be insufficient in establishing a correct diagnosis for the presence or absence of the respective types of TMJ ID. Regarding the diagnosis of absence or presence of TMJ ID, the results demonstrate high-resolution (HR)-US to be sensitive in detecting the absence, and reliable in predicting the presence of TMJ ID. In view of the fact that the 12.5 MHz US technique proved to be a reliable diagnostic aid for the detection of normal, and the prediction of abnormal DCR, the results of this study should be of further interest and encourage research in its potential uses and diagnostic capabilities.  相似文献   
9.
The objective of this study was to detect soluble-form tumour necrosis factor receptors (sTNFRs) in temporomandibular joint (TMJ) synovial fluid aspirates, and to compare the sTNFR concentrations between painful anterior disc displacement without reduction and osteoarthritis (ADDwoR/OA) and asymptomatic TMJs.Synovial fluid was sampled from the superior TMJ cavity of 11 painful ADDwoR/OA cases (mean age: 36.9 years) and 10 asymptomatic females (mean age: 24.7 years) by diluted aspiration. The concentrations of sTNFR-I and -II in the synovial fluid were measured using human sTNFR-I and -II enzyme-linked immunosorbent assays. The total protein concentrations in synovial fluids were measured using a bicinchoninic acid protein assay kit. All data were normalised to the total protein concentration of each sample.Two-way factorial analysis of variance and post hoc multiple comparison revealed that: (1). mean normalised sTNFR-I and -II concentrations were higher in TMJ synovial aspirates from ADDwoR/OA patients than from healthy controls; (2). in the ADDwoR/OA patients and the healthy controls, the sTNFR-I concentration in TMJ synovial aspirates was higher than the sTNFR-II concentration; and (3). high TMJ synovial aspirate sTNFR-II seemed to be associated with less TMJ pain and a less restricted range of mouth opening in the ADDwoR/OA patients.The concentrations of sTNFRs in TMJ synovial fluid are higher in the presence of painful ADDwoR/OA, which could modulate intracapsular inflammation.  相似文献   
10.
Authors – Wadhawan N, Kumar S, Kharbanda OP, Duggal R, Sharma R Aim – To document the alterations within the condyle‐glenoid fossa (C‐GF) complex and the positional changes of the glenoid fossa in the cranium after removable functional appliance therapy and after the completion of fixed appliance therapy. Setting and Sample – The Department of Orthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India. The study sample consisted of 12 growing children (eight girls and four boys) between 10 and 14 years of age with skeletal Class II division 1 malocclusion selected on well defined criteria. Materials and Methods – All patients were treated with either the Twin Block or the Bionator appliance followed by fixed appliances. Mean total treatment duration was 28 months. The changes in and around the C‐GF complex were evaluated using MRI at pre‐treatment stage, after functional appliance therapy and at the completion of fixed mechanotherapy. Results – Forward condylar position within the glenoid fossa and articular disc retrusion with respect to the condylar head were statistically significant after functional appliance therapy. However, the condyles had a relatively concentric position within the glenoid fossa, while the articular disc resumed its pre‐treatment position at the end of the treatment. Linear measurements from the centre of the external auditory meatus to the post‐glenoid spine revealed a 1.3‐mm forward relocation of the post‐glenoid spine along the Frankfurt Horizontal plane. Conclusions – Forward relocation of the C‐GF complex seems to be one of the mechanisms of action of functional appliances, while the internal anatomic arrangement within the temporomandibular joint (TMJ) complex normalizes to its pre‐treatment position.  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