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   49682篇
  免费   3041篇
  国内免费   241篇
耳鼻咽喉   511篇
儿科学   923篇
妇产科学   632篇
基础医学   6503篇
口腔科学   1082篇
临床医学   5185篇
内科学   10911篇
皮肤病学   997篇
神经病学   5808篇
特种医学   2522篇
外科学   8332篇
综合类   301篇
一般理论   13篇
预防医学   2283篇
眼科学   659篇
药学   2968篇
中国医学   69篇
肿瘤学   3265篇
  2023年   434篇
  2022年   692篇
  2021年   1426篇
  2020年   849篇
  2019年   1282篇
  2018年   1445篇
  2017年   1136篇
  2016年   1358篇
  2015年   1568篇
  2014年   1979篇
  2013年   2443篇
  2012年   3939篇
  2011年   3964篇
  2010年   2343篇
  2009年   2118篇
  2008年   3374篇
  2007年   3454篇
  2006年   3205篇
  2005年   3145篇
  2004年   2774篇
  2003年   2650篇
  2002年   2391篇
  2001年   453篇
  2000年   352篇
  1999年   416篇
  1998年   485篇
  1997年   365篇
  1996年   290篇
  1995年   224篇
  1994年   221篇
  1993年   168篇
  1992年   149篇
  1991年   147篇
  1990年   106篇
  1989年   97篇
  1988年   102篇
  1987年   74篇
  1986年   87篇
  1985年   81篇
  1984年   107篇
  1983年   90篇
  1982年   78篇
  1981年   59篇
  1980年   64篇
  1979年   51篇
  1978年   56篇
  1977年   53篇
  1976年   48篇
  1975年   50篇
  1974年   50篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
The authors present a case of amyloid infiltration involving the trigeminal nerve that mimicked a malignant cavernous sinus tumor with perineural tumor infiltration. A 64-year-old man presented with trigeminal nerve numbness. Imaging revealed a plaque-like enhancing lesion along the right lateral cavernous sinus extending anteriorly into Meckel's cave and involving the proximal V2 and V3 branches of the trigeminal nerve. The patient underwent an extradural frontotemporal craniotomy with middle fossa exposure of the cavernous sinus to diagnose and treat the presumed malignant cavernous sinus tumor. A reddish mass involving the lateral dural wall of the cavernous sinus was resected. The gasserian ganglion, V2, and V3, the latter of which was biopsied, were enlarged. Permanent histopathological studies showed microscopic eosinophilic, amorphous material, which stained positive for Congo red, and an absence of neoplastic cells. The final diagnosis was amyloidoma. Thus, amyloidomas can involve the trigeminal nerve or ganglia and should be considered in the differential diagnosis of a cavernous sinus lesion mimicking a tumor. Patients may have symptomatic improvement of trigeminal neuropathy with resection of the amyloidoma outside the nerve capsule that is compressing the nerve, while resection of the lesion from within the capsule may result in permanent trigeminal nerve dysfunction.  相似文献   
34.
In order to establish a venom fingerprint and a peptide profile of the Lasiodora parahybana tarantula venom gland, we used conventional methods such as reversed phase liquid chromatography coupled to an electrospray-ionisation hybrid quadrupole time of flight mass spectrometer (LC/ESI-QqTOFMS), matrix-assisted laser desorption/ionization time-of-flight-MS (MALDI-TOFMS) and direct study of L. parahybana venom by nanospray-ionization QqTOFMS (nanoESI-QqTOFMS) and a new technology for the direct analysis of fresh tissues using MALDI-TOFMS. The analysis of the crude venom allowed the characterization of specific juvenile and adult biomarkers. In situ MALDI analysis of L. parahybana venom gland sections revealed different peptide expression levels all along the gland and non-processed peptide precursors, demonstrating the power of the method for the dynamic investigation of peptide evolution in the venom gland of spiders.  相似文献   
35.
Abstract Objective: To define the diagnostic accuracy of clinical examination in patients with impaired consciousness or endotracheal intubation to detect pelvic ring fractures and to identify those with severe bleeding. Methods: Included in this prospective data collection with retrolective data analysis were a consecutive series of blunt trauma victims with either a Glasgow Coma Scale ≤ 13 or tracheal intubation. Clinical examination comprised testing for stability of the iliac wings. Results: From 784 subjects (injury severity score 23.3 ± 17.4) 93 patients (11.9%) were found to have a pelvic ring fracture. Clinical instability of the pelvic ring was found in 42 patients. There was only one false positive. Fifty-two fractures could not be identified by clinical examination, including nine fractures (17%) that required surgical fracture stabilization (sensitivity of clinical examination 44.1%). Seventeen fractures (18.3%) were associated with a blood loss larger than 20% of circulating blood volume. Sixteen of those were identified by clinical instability of the pelvic ring (sensitivity 94.1%, specificity 97.0%, positive predictive value 38.1%, negative predictive value 99.9%). Conclusions: Clinical examination for stability of the pelvis in this selected group of patients missed a significant number of pelvic ring fractures including fractures that require surgical stabilization. The finding of a clinically unstable identifies most of the patients with the pelvic ring fracture being a major source of bleeding. A stable pelvis makes pelvic ring fracture as being the source of bleeding quite unlikely.  相似文献   
36.

Introduction  

Planning human resources for health (HRH) is a complex process for policy-makers and, as a result, many countries worldwide swing from surplus to shortage. In-depth case studies can help appraising the challenges encountered and the solutions implemented. This paper has two objectives: to identify the key challenges in HRH planning in Belgium and to formulate recommendations for an effective HRH planning, on the basis of the Belgian case study and lessons drawn from an international benchmarking.  相似文献   
37.
38.
OBJECTIVE: The aim of this study was to evaluate soft tissue image quality of a mobile cone-beam computed tomography (CBCT) scanner with an integrated flat-panel detector. STUDY DESIGN: Eight fresh human cadavers were used in this study. For evaluation of soft tissue visualization, CBCT data sets and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) data sets were acquired. Evaluation was performed with the help of 10 defined cervical anatomical structures. RESULTS: The statistical analysis of the scoring results of 3 examiners revealed the CBCT images to be of inferior quality regarding the visualization of most of the predefined structures. Visualization without a significant difference was found regarding the demarcation of the vertebral bodies and the pyramidal cartilages, the arteriosclerosis of the carotids (compared with CT), and the laryngeal skeleton (compared with MRI). Regarding arteriosclerosis of the carotids compared with MRI, CBCT proved to be superior. CONCLUSIONS: The integration of a flat-panel detector improves soft tissue visualization using a mobile CBCT scanner.  相似文献   
39.
40.
Development of the central nervous system (CNS) involves the transformation of a two-dimensional epithelial sheet of uniform ectodermal cells, the neuroectoderm, into a highly complex three-dimensional structure consisting of a huge variety of different neural cell types. Characteristic numbers of each cell type become arranged in reproducible spatial patterns, which is a prerequisite for the establishment of specific functional contacts. The fruitfly Drosophila is a suitable model to approach the mechanisms controlling the generation of cell diversity and pattern in the developing CNS, as it allows linking of gene function to individually identifiable cells. This review addresses aspects of the formation and specification of neural stem cells (neuroblasts) in Drosophila in the light of recent studies on their segmental diversification.  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