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   1469篇
  免费   114篇
  国内免费   30篇
耳鼻咽喉   12篇
儿科学   25篇
妇产科学   13篇
基础医学   154篇
口腔科学   121篇
临床医学   117篇
内科学   95篇
皮肤病学   8篇
神经病学   113篇
特种医学   65篇
外科学   385篇
综合类   151篇
预防医学   122篇
眼科学   11篇
药学   81篇
  2篇
中国医学   69篇
肿瘤学   69篇
  2024年   5篇
  2023年   58篇
  2022年   70篇
  2021年   82篇
  2020年   64篇
  2019年   56篇
  2018年   63篇
  2017年   78篇
  2016年   58篇
  2015年   53篇
  2014年   116篇
  2013年   91篇
  2012年   74篇
  2011年   83篇
  2010年   68篇
  2009年   68篇
  2008年   61篇
  2007年   69篇
  2006年   54篇
  2005年   48篇
  2004年   47篇
  2003年   36篇
  2002年   20篇
  2001年   16篇
  2000年   26篇
  1999年   17篇
  1998年   12篇
  1997年   8篇
  1996年   11篇
  1995年   9篇
  1994年   10篇
  1993年   5篇
  1992年   8篇
  1991年   5篇
  1990年   7篇
  1989年   6篇
  1988年   8篇
  1987年   7篇
  1986年   1篇
  1985年   7篇
  1984年   4篇
  1983年   4篇
  1982年   3篇
  1981年   4篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1976年   3篇
  1973年   3篇
排序方式: 共有1613条查询结果,搜索用时 15 毫秒
41.
The loss of regional cervical sagittal alignment and the progressive development of cervical kyphosis is a factor in the advancement of myelopathy. Adequate decompression of the spinal canal along with reestablishment of cervical lordosis are desired objective with regard to the surgical treatment of patients with cervical spondylotic myelopathy. A retrospective chart review was conducted in which patients who underwent either a combined anterior/posterior instrumentation and decompression or a posterior alone instrumentation and decompression for the treatment of CSM at our institution were identified. Any patient undergoing operative intervention for trauma, infection or tumors were excluded. Similarly, patients undergoing posterior instrumentation with constructs extending beyond the level of C2–C7 were similarly excluded from this study. A total of 67 patients met the inclusion criteria for this study. A total of 32 patients underwent posterior alone surgery and the remaining 35 underwent combined anterior/posterior procedure. Radiographic evaluation of patient’s preoperative and postoperative cervical lordosis as measured by the C2–C7 Cobb angle was performed. Each patient’s preoperative and postoperative functional disability as enumerated by the Nurick score was also recorded. Statistical analysis was conducted to determine if there was a significant relationship between improvement in cervical lordosis and improvement in patient’s clinical outcomes as enumerated by the Nurick Score in patients undergoing posterior alone versus combined anterior/posterior decompression, instrumentation and fusion of the cervical spine.  相似文献   
42.
43.
可逆性上矢状窦血栓大鼠模型的建立   总被引:1,自引:0,他引:1  
目的建立可逆性上矢状窦血栓(SSST)大鼠模型,观察模型的稳定性和成功率。方法取雄性SD大鼠90只,随机分为模型组和对照组,每组45只;模型组采用上矢状窦局部置管并注射活化部分凝血活酶试剂建立大鼠SSST模型;对照组采用上矢状窦三氯化铁滤纸贴敷法建立SSST模型。两组于手术后24h行MRI及MR静脉造影(MRV),确定造模是否成功。模型成功后,分别于1、2、3、4周行MRI、MRV,观察上矢状窦再通情况及脑组织改变;取大鼠上矢状窦顶叶皮质脑组织标本行病理学观察。结果模型组模型成功41只,成功率为91%;总再通率为10%;对照组模型成功34只,成功率为75%,总再通率为45%。两组比较差异有统计学意义,P〈0.05。模型组大鼠脑组织水肿及梗死较对照组明显,而内皮细胞损伤较对照组轻微。结论改良法建立的大鼠可逆性上矢状窦血栓模型成功率高、稳定和重复性好。  相似文献   
44.
Background and aimsMetabolic syndrome (MetS) affects ~10% of adolescents and is associated with cardiometabolic disease risk. The most prevalent MetS component is abdominal obesity. Healthy diet and physical activity (PA) are inversely associated with abdominal obesity and may reduce MetS risk in youth. Our aim was to examine associations of diet, activity, and abdominal obesity with MetS z-score (MetS-z).Methods and resultsAn analysis of National Health and Nutrition Examination Survey (NHANES) 2011–2016 data in adolescents was performed. Healthy Eating Index (HEI)- 2015 scores were calculated for diet quality, PA habits were used to determine alignment with national guidelines, and abdominal obesity was assessed by sagittal abdominal diameter (SAD). MetS-z represented severity or potential risk for MetS. Multivariable regression evaluated the relationships of HEI, SAD and PA with MetS-z. Among 1214 black and white adolescents, SAD was significantly associated with MetS-z [β (95% CI) = 0.17 (0.16, 0.19); P <0.0001] while HEI-2015 components showed associations with MetS-z overall (HEI total, dairy, and sodium scores), and by sex (total, refined grains, dairy for males; added sugar, protein, whole grains for females). Mean HEI-2015 score was 47.4/100 (51.6 using the population-ratio method), and the proportion of adolescents meeting national PA guidelines was 37.6%, yet PA was not a significant predictor of MetS-z.ConclusionsUS adolescents have poor diet quality and fewer than half meet PA guidelines. Strategies for preventing MetS and related conditions in adolescence should focus on weight management – specifically, abdominal fat reduction – with individualized diet counseling.  相似文献   
45.
AimTo explore the relationships between transient structural brain patterns on MRI at preterm and at term-equivalent age (TEA) as a predictor of general movements (GMs) and motor development at 1-year corrected age (CA) in very preterm infants.MethodsIn this prospective study, 30 very preterm infants (median = 28wks; 16 males) had structural magnetic resonance imaging (MRI) at preterm (median = 31wks + 6d) and at TEA (median = 40wks) and neuromotor assessments. The quality of GMs was assessed by Prechtl’s general movements assessment and a detailed analysis of the motor repertoire was performed by calculating a motor optimality score (MOS), both at term age and at 3 months post-term. Motor development at 1-year CA was evaluated with the Infant Motor Profile (IMP). Associations between qualitative MRI findings and neuromotor scores were investigated.ResultsAbnormal GMs and low motor performance at 1-year CA were associated with the poor visibility of transient structural pattern, that is with sagittal strata.InterpretationTransient structural MRI pattern, sagittal strata, at preterm age is related to the quality of GMs and later motor development in preterm infants. This transient fetal brain compartment may be considered as a component of neurobiological basis for early neuromotor behavior, as expressed by GMs.  相似文献   
46.
PurposeThe purpose of this study was to examine the changes in the mandibular border movement between class II and class III jaw deformity patients before and after orthognathic surgery, by using the same device.Subjectsand Methods: Eighty one patients (28 in class II and 53 in class III) who underwent sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy using absorbable plate fixation and 27 controls with normal occlusion were enrolled. Mandibular border movement (observed using a kinesiograph) was recorded with a mandibular movement measure system (K7) before surgery, and at 6 months and 1 year after surgery. Time-course changes of 5 components of the mandibular border movement (MVO: Maximum vertical opening, CO to MAP: Maximum antero-posterior movement from centric occlusion, MLDL: maximum lateral deviation left, MLDR: maximum lateral deviation right, CO to MO: centric occlusion to maximum opening) were compared between classes II, III and controls statistically. The relationship between lateral cephalometric measurements and the components of mandibular border movement was also examined.ResultsThere was a significant difference in CO to MAP (P = 0.0025) and CO to MO (P < 0.0001) between class II and class III in the time-course change.In class III, mean and standard deviation of MVO were 44.5 ± 6.7 mm before surgery and 39.8 ± 6.8 mm after 1 year. Mean and standard deviation of CO to MAP were 25.2 ± 6.8 mm before surgery and 21.5 ± 7.9 mm after 1 year. Mean and standard deviation of CO to MO were 53.4 ± 9.0 mm before surgery and 47.3 ± 8.4 mm after 1 year.In class II, mean and standard deviation of MVO were 38.8 ± 5.8 mm before surgery and 36.2 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MAP were 18.0 ± 6.3 mm before surgery and 17.8 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MO were 43.1 ± 7.5 mm before surgery and 39.6 ± 10.5 mm after 1 year.In MVO, CO to MAP and CO to MO, the values after 1 year did not significantly reach the pre-operative values in class III (P = 0.0001, P = 0.0007 and P < 0.0001), although there was no significant difference between pre-operation and after 1 year in class II.In CO to MO, class II (mean and standard deviation 39.6 ± 10.5 mm) and class III (mean and standard deviation 47.3 ± 8.4 mm) still remained smaller values than control (mean and standard deviation 52.7 ± 9.2 mm) after 1 year (P < 0.0001 and P = 0.0095).ConclusionThis study suggests that bi-maxillary surgery can have more influence on the reduction in the range of mandibular border movement including vertical or antero-posterior motion than lateral deviation motion, in both groups. The difference in the time-course change in the mandibular border movement between the groups might depend more on the mandibular length than on the movement direction of the mandible by surgery such as advancement or setback.  相似文献   
47.
PurposeThis study aimed to assess the factors that can possibly affect the positioning of the inferior alveolar nerve (IAN) in the proximal or distal segment following sagittal split osteotomy (SSO).Materials and methodsThis was a prospective cohort study. The patients were assigned according to the position of the IAN: the IAN was attached to the buccal plate in group 1 (27 SSOs), while it was in the distal segment in group 2 (83 SSOs).ResultsThe mean of the buccolingual thickness of the proximal segment at the vertical cut of the osteotomy (BLTP) was 5.0 ± 0.62 mm in group 1 and 4.16 ± 0.72 mm in group 2. The mean of the distance between the IAN and the external cortical bone at the distal of the second molar before the osteotomy (IANB) was 0.5 ± 0.24 mm in group 1 and 1.24 ± 0.45 mm in group 2. There were significant differences for the mean BLTP and IANB between the two groups (P = 0.001).ConclusionIt seems that the thickness of the buccal plate of the proximal segment, the distance from the IAN to the external cortical bone, the osteotomy technique, and the presence or absence of impacted third molars may be associated with the positioning of the IAN following SSO.  相似文献   
48.
目的探讨矢状切面在妊娠早期超声筛查胎儿腭裂中的价值。 方法回顾性选择2018年1月至2019年12月广东省妇幼保健院的31例妊娠早期腭裂的胎儿,分析头颈部超声检查矢状切面的异常征象,总结不同类型腭裂在矢状切面的超声表现以及其他结构异常情况。 结果(1)超声声像图表现:28例出现上颌骨间隙(90.3%,28/31),其中14例为单侧腭裂,5例为双侧腭裂,9例为正中腭裂;27例表现为缺失“重叠线征”(87.1%,27/31),其中正中腭裂5例,单侧腭裂15例,双侧腭裂6例,单纯腭裂1例;6例颌骨前突(19.4%,6/31),均为双侧唇腭裂。(2)合并其他结构异常情况:妊娠早期及妊娠中期诊断腭裂病例中,合并胎儿结构异常分别占75.0%(15/20)、45.5%(5/11),颈项透明层增厚分别占60.0%(12/20)、36.4%(4/11)。 结论矢状切面上颌间隙和缺失“重叠线征”是妊娠早期筛查胎儿腭裂的重要线索,颌骨前突是双侧腭裂的特征性超声表现。  相似文献   
49.
The juncturae tendinum and sagittal bands transmit precise forces through the dorsum of the hand. Both structures are integral in the mechanics of normal digital extension and in stabilization of the metacarpophalangeal (MCP) joints. Extensor tendon injury, or rupture/attenuation of sagittal bands and/or juncturae tendinum, may disrupt the kinematic chain and lead to a number of abnormal hand postures and motions. Early treatment of extensor tendon and/or sagittal band injury is dependent upon proper recognition of primary pathology. Proper evaluation and the use of special clinical tests should be implemented to rule out other pathologies. Once diagnosed, treatment may consist of relative motion splinting and standard pain/edema control measures to increase joint motion, tendon excursion, and functional use of the hand.  相似文献   
50.

Objective

Oxidative metabolism is impaired in several medical conditions including psychiatric disorders, and this imbalance may be involved in the etiology of these diseases. The present study evaluated oxidative balance in pediatric and adolescent patients with attention deficit hyperactivity disorder (ADHD).

Methods

The study included 48 children and adolescents (34 male, 14 female) with ADHD who had no neurological, systemic, or comorbid psychiatric disorders, with the exception of oppositional defiant disorder (ODD), and 24 sex- and age-matched healthy controls (17 male and seven female).

Results

TAS was significantly lower, and TOS and OSI were significantly higher in patients with ADHD than in healthy controls. Total antioxidant levels were lower in patients with comorbid ODD than in those with no comorbidity. No difference was found in TOS or OSI among the ADHD subtypes; however, TAS was higher in the attention-deficient subtype.

Conclusion

Our findings demonstrated that oxidative balance is impaired and oxidative stress is increased in children and adolescents with ADHD. This results are consistent with those of previous studies.  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