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   78478篇
  免费   7306篇
  国内免费   5013篇
耳鼻咽喉   619篇
儿科学   1028篇
妇产科学   463篇
基础医学   6007篇
口腔科学   1876篇
临床医学   9405篇
内科学   8143篇
皮肤病学   1103篇
神经病学   2480篇
特种医学   3406篇
外国民族医学   20篇
外科学   8863篇
综合类   19401篇
现状与发展   17篇
一般理论   8篇
预防医学   7438篇
眼科学   1184篇
药学   8845篇
  81篇
中国医学   6226篇
肿瘤学   4184篇
  2024年   223篇
  2023年   929篇
  2022年   1959篇
  2021年   3155篇
  2020年   2759篇
  2019年   1784篇
  2018年   2001篇
  2017年   2248篇
  2016年   1804篇
  2015年   3273篇
  2014年   4433篇
  2013年   5068篇
  2012年   7108篇
  2011年   7734篇
  2010年   6738篇
  2009年   5941篇
  2008年   6079篇
  2007年   5583篇
  2006年   5297篇
  2005年   4259篇
  2004年   2972篇
  2003年   2419篇
  2002年   1876篇
  2001年   1492篇
  2000年   1165篇
  1999年   692篇
  1998年   342篇
  1997年   324篇
  1996年   214篇
  1995年   186篇
  1994年   184篇
  1993年   96篇
  1992年   74篇
  1991年   74篇
  1990年   47篇
  1989年   38篇
  1988年   41篇
  1987年   33篇
  1986年   30篇
  1985年   13篇
  1984年   10篇
  1983年   16篇
  1982年   8篇
  1965年   4篇
  1964年   10篇
  1963年   4篇
  1959年   4篇
  1958年   4篇
  1957年   9篇
  1956年   6篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
41.
The objective of the present study was to evaluate the clinical, radiological, and functional outcomes of a subscapularis transthoracic surgical approach and a posterolateral surgical approach with debridement, bone graft fusion, and internal fixation for the treatment of upper thoracic tuberculosis.There is currently debate over the best surgical approach for the treatment of upper thoracic tuberculosis. Traditionally, the subscapularis transthoracic approach has been preferred; however, the posterolateral approach has gained popularity in the past few years.A prospective, consecutive cohort of 43 upper thoracic tuberculosis patients with a mean age of 39 years (range: 20–52 years) was followed up for a minimum of 12 months (range: 12–60 months). Patients were randomly divided into 2 groups. Group A (n = 21) was treated by the subscapularis transthoracic approach and group B (n = 22) was treated by the posterolateral approach. All cases were evaluated for clinical, radiological, and functional outcomes. Intraoperative blood loss, operative duration, intraoperative and postoperative complications, hospital stay, the cure rate, fusion time, and the Frankel scale were used for clinical and functional evaluation, whereas the kyphosis angle was used for radiological evaluation.Grafted bones were fused by 10 months in all cases. There was no statistically significant difference between groups before surgery in terms of gender, age, segmental tuberculosis, erythrocyte sedimentation rate (ESR), Frankel scale, or Cobb''s angle (P > 0.05). The average operative duration for Group B was lower than that of Group A. There were no significant differences in intraoperative blood loss, intraoperative and postoperative complications, hospital stay, grafted bone fusion time, or cure rate between groups (P > 0.05). The Cobb''s angle correction rate for group B (68.5%) was significantly better than that of group A (30.9%). The neurological score showed significant postoperative improvement in both groups, with no significant difference between the groups.The subscapularis transthoracic approach and the posterolateral approach with debridement, bone graft fusion, and internal fixation are both sufficient and satisfactory for the surgical treatment of upper thoracic tuberculosis. However, the posterolateral approach is superior to the subscapularis transthoracic approach in terms of surgical trauma, operative time, and kyphosis correction.  相似文献   
42.
本文报道并分析8例寄生虫病例,其中包括脑裂头蚴病、眼部裂头蚴病、肺吸虫幼虫移行症、肺吸虫病、钩虫病、肝吸虫病、包虫病和广州管圆线虫病各1例。8例寄生虫病均有不同程度的误诊,其中6例在寄生虫抗体筛查检测阳性后得以确诊。因此,寄生虫病应引起临床医生的重视,抗体筛查有助于发现寄生虫病例。  相似文献   
43.
Chen  Si-Bao  Tian  Xiu-Zhi  Ding  Chris H. Q.  Luo  Bin  Liu  Yi  Huang  Hao  Li  Qiang 《Cognitive computation》2020,12(6):1144-1153

In the area of large-scale graph data representation and semi-supervised learning, deep graph-based convolutional neural networks have been widely applied. However, typical graph convolutional network (GCN) aggregates information of neighbor nodes based on binary neighborhood similarity (adjacency matrix). It treats all neighbor nodes of one node equally, which does not suppress the influence of dissimilar neighbor nodes. In this paper, we investigate GCN based on similarity matrix instead of adjacency matrix of graph nodes. Gaussian heat kernel similarity in Euclidean space is first adopted, which is named EGCN. Then biologically inspired manifold similarity is trained in reproducing kernel Hilbert space (RKHS), based on which a manifold GCN (named MGCN) is proposed for graph data representation and semi-supervised learning with four different kernel types. The proposed method is evaluated with extensive experiments on four benchmark document citation network datasets. The objective function of manifold similarity learning converges very quickly on different datasets using various kernel functions. Compared with state-of-the-art methods, our method is very competitive in terms of graph node recognition accuracy. In particular, the recognition rates of MGCN (Gaussian kernel) and MGCN (Polynomial Kernel) outperform that of typical GCN about 3.8% on Cora dataset, 3.5% on Citeseer dataset, 1.3% on Pubmed dataset and 4% on Cora_ML dataset, respectively. Although the proposed MGCN is relatively simple and easy to implement, it can discover local manifold structure by manifold similarity learning and suppress the influence of dissimilar neighbor nodes, which shows the effectiveness of the proposed MGCN.

  相似文献   
44.
目的探讨PBL与思维导图相结合教学模式在临床教学中的应用。方法本文研究对象为在我院见习的临床本科生,为大理大学2015级一个班级,共55名学生,数据收集时间为2019年1月;按照授课方式的差异将学生分为实验班与对照班,实验班27名学生,对照班28名学生;对照班实施常规教学法,实验班实施PBL与思维导图相结合教学法。结果实验班教学结束测试得分为(85.60±3.46)分,对照班教学结束测试得分为(77.48±3.12)分,差异具有统计学意义(P<0.05);实验班教学方式满意度评分为(90.35±4.12)分,对照班教学方式满意度评分为(80.25±4.05)分,差异具有统计学意义(P<0.05)。结论在临床教学中采用PBL与思维导图相结合教学模式,能够提高学生的专业知识掌握水平与对教学模式的认可度。  相似文献   
45.
Conservation laws are considered to be fundamental laws of nature. It has broad applications in many fields, including physics, chemistry, biology, geology, and engineering. Solving the differential equations associated with conservation laws is a major branch in computational mathematics. The recent success of machine learning, especially deep learning in areas such as computer vision and natural language processing, has attracted a lot of attention from the community of computational mathematics and inspired many intriguing works in combining machine learning with traditional methods. In this paper, we are the first to view numerical PDE solvers as an MDP and to use (deep) RL to learn new solvers. As proof of concept, we focus on 1-dimensional scalar conservation laws. We deploy the machinery of deep reinforcement learning to train a policy network that can decide on how the numerical solutions should be approximated in a sequential and spatial-temporal adaptive manner. We will show that the problem of solving conservation laws can be naturally viewed as a sequential decision-making process, and the numerical schemes learned in such a way can easily enforce long-term accuracy. Furthermore, the learned policy network is carefully designed to determine a good local discrete approximation based on the current state of the solution, which essentially makes the proposed method a meta-learning approach. In other words, the proposed method is capable of learning how to discretize for a given situation mimicking human experts. Finally, we will provide details on how the policy network is trained, how well it performs compared with some state-of-the-art numerical solvers such as WENO schemes, and supervised learning based approach L3D and PINN, and how well it generalizes.  相似文献   
46.
目的探讨补骨脂素抗增生性瘢痕的作用机制。方法体外培养成纤维细胞,按随机数字表法分为正常组(培养正常成纤维细胞)、瘢痕组(培养增生性瘢痕成纤维细胞)、TGF-β1组(10 ng/ml TGF-β1处理增生性瘢痕成纤维细胞5 min^12 h)、Smurf2 RNA干扰组[Smad泛素化调节因子2(Smad ubiquitin regulatory factor2,Smurf2)siRNA转染增生性瘢痕成纤维细胞72 h]、补骨脂素组(10μmol/L补骨脂素处理增生性瘢痕成纤维细胞继续培养72 h)、补骨脂素+TGF-β1组(增生性瘢痕成纤维细胞加入补骨脂素培养72 h后加入TGF-β1培养6 h)。采用Western blot法检测Smurf2、α-平滑肌肌动蛋白(α-actin SMA,α-SMA)蛋白表达;RT-PCR法检测Ⅰ型胶原蛋白mRNA表达;ELISA法检测TGF-β1蛋白分泌。结果与正常组比较,瘢痕组Smurf2蛋白[(0.83±0.08)比(0.38±0.07)]表达增加(P<0.05);与瘢痕组比较,Smurf2 RNA干扰组TGF-β1[(2.2±0.18)比(4.2±0.47)]表达降低(P<0.05);TGF-β1组Smurf2[(0.71±0.06)比(0.42±0.04)]、α-SMA[(1.42±0.12)比(0.91±0.09)]蛋白表达增加(P<0.05),Ⅰ型胶原蛋白mRNA[(0.72±0.09)比(0.41±0.07)]表达增加(P<0.05);补骨脂素组Smurf2[(0.05±0.01)比(0.42±0.04)]、α-SMA[(0.71±0.07)比(0.91±0.09)]蛋白表达降低(P<0.05),Ⅰ型胶原蛋白mRNA表达[(0.12±0.04)比(0.41±0.07)]降低(P<0.05)。结论补骨脂素可能通过TGF-β1/Smurf2信号通路抑制α-SMA蛋白表达,从而降低Ⅰ型胶原蛋白表达,起到抑制瘢痕形成的作用。  相似文献   
47.
目的观察改良俯卧位对俯卧位通气(PPV)临床疗效及并发症的影响。方法将该院呼吸和危重症医学科行PPV的52例患者随机分为对照组和实验组各26例,对照组应用常规方法进行PPV,实验组采用改良俯卧位进行PPV。比较两组患者PPV的临床效果和并发症发生情况。结果两组间俯卧位前和俯卧位后12 h的氧合指数无明显差异(P>0.05);两组患者俯卧位后12 h的氧合指数均较各组俯卧位前明显改善(P<0.05);两组患者气管插管脱出、血流动力学显著波动、误吸和面部水肿的发生率无显著差异(P>0.05);实验组皮肤压疮的发生率明显低于对照组(P<0.05)。结论改良俯卧位对PPV的临床疗效无显著影响,但可以降低皮肤压疮的发生率。  相似文献   
48.
目的 研究皖南地区儿童呼吸道病原体感染的流行病学特点,探讨混合病原体感染患儿血清中干扰素诱生蛋白10(interferon-inducible protein-10,IP-10),单核细胞趋化蛋白-1( monogyte chemoattractant protein-1),MCP-1表达水平在急性呼吸道感染诊断中的应用价值。方法 收集2017年6月~2019年6月皖南医学院第一、二附属医院急性呼吸道感染患儿血标本,采用间接免疫荧光法检测呼吸道九项病原体IgM,分析不同年龄段呼吸道病原体感染的差异性。采用酶联免疫吸附试验检测混合感染患儿血清中IP-10,MCP-1的表达水平,分析炎症因子表达水平与疾病严重程度的相关性。结果 5 122例急性呼吸道感染患儿中,以肺炎支原体感染率最高,混合感染患儿共544例,以肺炎支原体联合呼吸道合胞病毒感染率最高。检测血清中的CRP,IP-10和MCP-1的表达水平相比较单独感染组,混合感染组升高更为明显,对比组之间的差异均具有统计学意义(F=1.045~4.889,均P<0.05)。相关性研究分析显示,混合感染组IP-10,MCP-1与CRP 表达水平呈正相关性(r = 0.612,P<0.001; r= 0.804,P<0.001)。结论 急性呼吸道感染患儿中,混合感染更易表现为咳嗽、鼻塞流涕及发热等症状,同时炎症反应增强,病情的严重程度增加,血清IP-10和MCP-1表达水平可作为急性呼吸道感染病情严重程度指标之一。  相似文献   
49.

BACKGROUND CONTEXT

Although 40% of adolescent idiopathic scoliosis (AIS) patients present with chronic back pain, the pathophysiology and underlying pain mechanisms remain poorly understood. We hypothesized that development of chronic pain syndrome in AIS is associated with alterations in pain modulatory mechanisms.

PURPOSE

To identify the presence of sensitization in nociceptive pathways and to assess the efficacy of the diffuse noxious inhibitory control in patients with AIS presenting with chronic back pain.

STUDY DESIGN

Cross-sectional study.

PATIENT SAMPLE

Ninety-four patients diagnosed with AIS and chronic back pain.

OUTCOME MEASURES

Quantitative sensory testing (QST) assessed pain modulation and self-reported questionnaires were used to assess pain burden and health-related quality of life.

METHODS

Patients underwent a detailed pain assessment using a standard and validated quantitative sensory testing (QST) protocol. The measurements included mechanical detection thresholds (MDT), pain pressure threshold (PPT), heat pain threshold (HPT), heat tolerance threshold (HTT), and a conditioned pain modulation (CPM) paradigm. Altogether, these tests measured changes in regulation of the neurophysiology underlying the nociceptive processes based on the patient's pain perception. Funding was provided by The Louise and Alan Edwards Foundation and The Shriners Hospitals for Children.

RESULTS

Efficient pain inhibitory response was observed in 51.1% of patients, while 21.3% and 27.7% had sub-optimal and inefficient CPM, respectively. Temporal summation of pain was observed in 11.7% of patients. Significant correlations were observed between deformity severity and pain pressure thresholds (p=.023) and CPM (p=.017), neuropathic pain scores and pain pressure thresholds (p=.015) and temporal summation of pain (p=.047), and heat temperature threshold and pain intensity (p=.048).

CONCLUSIONS

Chronic back pain has an impact in the quality of life of adolescents with idiopathic scoliosis. We demonstrated a high prevalence of impaired pain modulation in this group. The association between deformity severity and somatosensory dysfunction may suggest that spinal deformity can be a trigger for abnormal neuroplastic changes in this population contributing to chronic pain syndrome.  相似文献   
50.
目的: 评估液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)分析人全血中环孢素的基质效应,并探究其发生机理。方法: 全血裂解物的蛋白沉淀上清液用作全血基质。分别用乙腈水溶液和全血基质配制等浓度环孢素A(CyA)、环孢素C(CyC)的质控样品。分别在添加H+、NH4+和Na+的流动相中,用LC-ESI-MS/MS的MRM模式检测质控样品中CyA,CyC的[M+H]+、[M+NH4]+和[M+Na]+(M=CyA,CyC)峰面积,以其计算基质效应因子;用MS Scan模式检查质控样品中CyA、CyC色谱流出峰的质谱离子组成情况,用于判断基质效应原因。结果: 在添加H+、NH4+和Na+的流动相中,全血基质中CyA、CyC基质效应因子分别为-76.6%~-54.0%、-86.0%~-55.3%和-42.8%~-34.1%。在加H+、加NH4+流动相中,标准液加全血基质的CyA、CyC色谱峰的质谱中出现丰度很高的[M+Na]+和[M+K]+,在加Na+流动相中它们出现丰度很高的[M+K]+,而对应的定量离子[M+H]+、[M+NH4]+或[M+Na]+的丰度显著降低。结论: 全血基质对环孢素的LC-ESI-MS/MS分析产生明显的基质效应,其原因与基质中Na+、K+同添加在流动相中用于辅助电离的H+、NH4+或Na+竞争与环孢素加合,导致定量目标加合离子丰度显著降低有关。  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