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   2540篇
  免费   79篇
  国内免费   17篇
耳鼻咽喉   28篇
儿科学   203篇
妇产科学   126篇
基础医学   178篇
口腔科学   119篇
临床医学   189篇
内科学   460篇
皮肤病学   69篇
神经病学   129篇
特种医学   144篇
外科学   561篇
综合类   16篇
一般理论   2篇
预防医学   50篇
眼科学   143篇
药学   111篇
中国医学   6篇
肿瘤学   102篇
  2024年   1篇
  2023年   18篇
  2022年   15篇
  2021年   43篇
  2020年   35篇
  2019年   47篇
  2018年   42篇
  2017年   50篇
  2016年   70篇
  2015年   75篇
  2014年   74篇
  2013年   166篇
  2012年   195篇
  2011年   195篇
  2010年   103篇
  2009年   85篇
  2008年   178篇
  2007年   228篇
  2006年   210篇
  2005年   215篇
  2004年   148篇
  2003年   156篇
  2002年   96篇
  2001年   53篇
  2000年   45篇
  1999年   24篇
  1998年   2篇
  1997年   7篇
  1996年   4篇
  1995年   2篇
  1994年   2篇
  1993年   5篇
  1992年   5篇
  1991年   3篇
  1990年   3篇
  1989年   2篇
  1988年   8篇
  1987年   8篇
  1986年   3篇
  1985年   6篇
  1984年   2篇
  1977年   2篇
  1974年   1篇
  1973年   1篇
  1970年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有2636条查询结果,搜索用时 15 毫秒
71.

INTRODUCTION

Atypical presentations of appendix have been reported including backache, left lower quadrant pain and groin pain from a strangulated femoral hernia containing the appendix. We report a case presenting an epigastric pain that was diagnosed after computed tomography as a perforated appendicitis on intestinal malrotation.

PRESENTATION OF CASE

A 27-year-old man was admitted with a three-day history of epigastric pain. Physical examination revealed tenderness and defense on palpation of epigastric region. There was a left subcostal incision with the history of diaphragmatic hernia repair when the patient was 3 days old. He had an intestinal malrotation with the cecum fixed at the epigastric region and the inflamed appendix extending beside the left lobe of liver.

DISCUSSION

While appendicitis is the most common abdominal disease requiring surgical intervention seen in the emergency room setting, intestinal malrotation is relatively uncommon. When patients with asymptomatic undiagnosed gastrointestinal malrotation clinically present with abdominal pain, accurate diagnosis and definitive therapy may be delayed, possibly increasing the risk of morbidity and mortality.

CONCLUSION

Atypical presentations of acute appendicitis should be kept in mind in patients with abdominal pain in emergency room especially in patients with previous childhood operation for diaphragmatic hernia.  相似文献   
72.
73.
A one-step preparation method for hybrid electromagnetic nanomaterials based on polydiphenylamine (PDPA) and bimetallic Co–Fe particles in the absence and presence of single-walled carbon nanotubes (SWCNT) was proposed. During IR heating of PDPA in the presence of Co(ii) and Fe(iii) salts in an inert atmosphere at T = 450–600 °C, the polycondensation of diphenylamine (DPA) oligomers and dehydrogenation of phenyleneamine units of the polymer with the formation of C Created by potrace 1.16, written by Peter Selinger 2001-2019 N bonds and reduction of metals by evolved hydrogen with the formation of bimetallic Co–Fe particles dispersed in a polymer matrix occur simultaneously. When carbon nanotubes are introduced into the reaction system, a nanocomposite material is formed, in which bimetallic Co–Fe particles immobilized on SWCNT are distributed in the matrix of the polymer. According to XRD data, reflection peaks of bimetallic Co–Fe particles at diffraction scattering angles 2θ = 69.04° and 106.5° correspond to a solid solution based on the fcc-Co crystal lattice. According to SEM and TEM data, a mixture of particles with sizes of 8–30 nm and 400–800 nm (Co–Fe/PDPA) and 23–50 nm and 400–1100 nm (Co–Fe/SWCNT/PDPA) is formed in the nanocomposites. The obtained multifunctional Co–Fe/PDPA and Co–Fe/SWCNT/PDPA nanomaterials demonstrate good thermal, electrical and magnetic properties. The saturation magnetization of the nanomaterials is MS = 14.99–31.32 emu g−1 (Co–Fe/PDPA) and MS = 29.48–48.84 emu g−1 (Co–Fe/SWCNT/PDPA). The electrical conductivity of the nanomaterials reaches 3.5 × 10−3 S cm−1 (Co–Fe/PDPA) and 1.3 S cm−1 (Co–Fe/SWCNT/PDPA). In an inert medium, at 1000 °C the residue is 71–77%.

In a self-organizing system within one stage under IR heating conditions, hybrid nanomaterials are formed with a structure that contains bimetallic Co–Fe particles, free or immobilized on the SWCNT surface, dispersed in the polymer PDPA matrix.  相似文献   
74.
European Archives of Psychiatry and Clinical Neuroscience - Cognitive deficits are increasingly recognized as a core dimension rather than a consequence of schizophrenia (SCZ). The previous...  相似文献   
75.
76.
This experimental study was designed to assess and to compare intra-abdominal adhesions following the use of five commercially available prosthetic mesh grafts in the repair if abdominal wall defects. Sixty Wistar albino rats were randomly divided into six groups (n = 10). A 2 × 1 cm defect at abdominal wall was created and defects were closed either primarily or with one of the following prosthetic mesh grafts: monofilament polypropylene, polytetrafluoroethylene, sodium hyaluronate/carboxymethylcellulose-coated polypropylene, polypropylene/polyglactin 910 composite, or resorbable hydrophilic collagen-coated multifiber polyester. The severity of adhesions was graded, tensile strengths of adhesions were measured, and histopathological grades of inflammation and fibrosis were evaluated. Polypropylene mesh resulted in more adhesion formation in comparison to primary repair and other grafts used in this study, except polypropylene/polyglactin 910 composite mesh. In addition, the highest tensile strength of omental adhesions was detected in the polypropylene group (χ2 = 26.249; p =. 0001). Polyester composite mesh caused the least adhesion formation among the groups. Sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polyester composite meshes revealed the highest fibrosis scores (χ2 = 50.776; p =. 0001). The highest inflammatory activity was detected in the polytetrafluoroethylene mesh group (χ2 = 16.564; p =. 005). Thus, sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polytetrafluoroethylene meshes following polyester composite mesh were the minimal adhesion-forming grafts in this study. Disadvantages of the polytetrafluoroethylene mesh were lower fibrotic activity and higher inflammatory reaction to the graft.  相似文献   
77.
78.
Pulmonary arteriovenous malformation (AVM) is a rare vascular malformation of the lung that carries a considerable risk of serious complications such as cerebral embolism, brain abscess, and pulmonary hemorrhage. Embolization with coils or detachable balloons is currently the preferred treatment. Paradoxical embolization of coils and balloons may occur, especially in patients with large feeding arteries. This report describes an initial experience with the use of the Amplatzer Vascular Plug used for endovascular treatment of bilateral multiple pulmonary AVMs in an adult patient.  相似文献   
79.
80.
Cyclosporine A (CsA), broadly used in organ transplantation, may contribute to pathogenesis of osteoporosis. The aim of this study was to investigate the effects of CsA on alveolar bone in rats subjected or not to experimental periodontal disease using biochemical, radiographic, and histometric analysis. Forty Wistar rats were divided into 4 equal groups: Group I (Control), Group II (CsA was injected subcutaneously in a daily dose of 10 mg/kg), Group III (Ligature was placed around the mandibular molars), Group IV (Ligature+CsA). After 60 days, rats were decapitated, serum alkaline phosphatase and calcium levels were measured. Radiographic-alveolar bone loss (ABL), histometric-ABL, and percentage of new alveolar bone formation (NABF%) were determined on mandibular molars. Significant increase in serum alkaline phosphatase levels (p < 0.001), no significant difference in calcium levels were observed (p > 0.05) in Group IV compared to Group III. Radiographic and histometric-ABL were significantly less (p < 0.001), NABF% was significantly greater (p < 0.05) in Group IV than in Group III. No significant difference in any of the parameters between Group II and Group I was found. It can be concluded that in the presence of periodontal disease, CsA treatment may bring out an imbalance in the alveolar bone homeostasis by decreasing resorption and stimulating formation of alveolar bone in rats.  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