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   5364篇
  免费   272篇
  国内免费   29篇
耳鼻咽喉   58篇
儿科学   132篇
妇产科学   140篇
基础医学   626篇
口腔科学   122篇
临床医学   315篇
内科学   1199篇
皮肤病学   48篇
神经病学   308篇
特种医学   197篇
外科学   1053篇
综合类   36篇
预防医学   100篇
眼科学   439篇
药学   369篇
中国医学   9篇
肿瘤学   514篇
  2023年   31篇
  2022年   68篇
  2021年   105篇
  2020年   55篇
  2019年   65篇
  2018年   96篇
  2017年   78篇
  2016年   114篇
  2015年   111篇
  2014年   143篇
  2013年   183篇
  2012年   249篇
  2011年   311篇
  2010年   144篇
  2009年   133篇
  2008年   268篇
  2007年   241篇
  2006年   264篇
  2005年   237篇
  2004年   262篇
  2003年   249篇
  2002年   235篇
  2001年   192篇
  2000年   192篇
  1999年   192篇
  1998年   51篇
  1997年   56篇
  1996年   45篇
  1995年   54篇
  1994年   46篇
  1993年   34篇
  1992年   114篇
  1991年   101篇
  1990年   81篇
  1989年   98篇
  1988年   80篇
  1987年   92篇
  1986年   118篇
  1985年   78篇
  1984年   58篇
  1983年   39篇
  1980年   17篇
  1979年   28篇
  1978年   17篇
  1977年   24篇
  1975年   17篇
  1974年   18篇
  1970年   23篇
  1969年   24篇
  1967年   17篇
排序方式: 共有5665条查询结果,搜索用时 15 毫秒
101.
102.
A 69-year-old Japanese female was admitted to our hospital due to a 2-month history of vomiting after eating. Examination of the small intestinal tract revealed a tumor with calcification in the inner portion, from the horizontal portion to the ascending portion of the duodenum, and jejunojejunostomy was performed. The pathological findings of the tumor gave a diagnosis of non-Hodgkin's lymphoma, diffuse small cleaved cell (Working Formulation classification), B cell type, of the jejunum. Calcification is rarely found in untreated malignant lymphoma and 15 cases of untreated malignant lymphoma with calcification have been reviewed.  相似文献   
103.
Intervertebral disc degeneration and associated spinal disorders including low back pain are a leading source of morbidity and a major cause of work disability as well as increased health care costs. Recent advance of molecular biology enable us to utilize these new techniques for understanding disc cell function and mechanisms of disc degeneration. Furthermore, these new technology may open novel therapeutic strategy such as application of growth factors, stem cell therapy, and gene therapy to regenerate degenerated intervertebral discs.  相似文献   
104.
Somatostatin (SRIF)-like immunoreactivity (SLI) in the thyroid glands of human and several animal species were compared, and the SLI peptides were characterized chromatographically and immunologically. All specimens were extracted with 2 M acetic acid, and the SLI content determined by RIA. The SLI concentrations in guinea pigs [34.3 +/- (SE) 4.8 ng/mg protein] and rabbits (9.4 +/- 0.8 ng/mg protein) were much greater than those in other mammals: dogs, rats, mice, and humans. On gel filtration of extracts of the guinea pig, rabbit and dog thyroids, the major peak of SLI (1.6 K SLI) coeluted with synthetic SRIF-14 (S-14). Two other forms of SLI ("big" SLI and 3 K SLI) were also detected, although their relative proportions to total SLI were small (2.3 to 8.2%). The 3 K SLI and 1.6 K SLI from guinea pig and rabbit thyroids contained peptides coeluting with synthetic SRIF-28 (S-28) and S-14, respectively, on reverse-phase high performance liquid chromatography. The dilution curves of the two molecular forms of SLI, i.e. 3 K SLI and 1.6 K SLI, were parallel to the displacement curves of S-28 and S-14 in the SRIF RIA. It is concluded 1) that the thyroid contents of SLI varied greatly from species to species, with the highest content being found in guinea pig thyroids; 2) that in guinea pigs, rabbits, and dogs, the predominant form of thyroid SLI is 1.6 K SLI; and 3) that the 3 K SLI and 1.6 K SLI peptides from guinea pig and rabbit thyroids are immunologically and chromatographically indistinguishable from S-28 and S-14, respectively.  相似文献   
105.
A 59-year-old woman was admitted to our hospital because of recurrent follicular lymphorna (FL). Colonoscopic examination revealed a rectal submucosal tumor (SMT) without any erosions and ulcers. In this patient, it was difficult to distinguish non-Hodgkin‘s lymphoma (NHL) invasion from other disorders of the colon including carcinoid tumor merely based on endoscopic findings. Histopathologic and immunohistochemical studies on biopsy specimens showed an infiltration of atypical lymphocytes that were positive for CD20 and BCL2 but negative for UCHL-1. Fluorescence in situ hybridization on paraffin-embedded tissue sections (T-FISH) identified a translocation of BCL2 with IGHgene.Based on these findings, the tumor was defined as an invasion of FL. T-FISH method is useful for the detection of a monoclonality of atypical lymphocytes in an SMT of the gastrointestinal tract, and particularly for the detection of chromosomal translocations specific to lymphoma subtypes.  相似文献   
106.
BackgroundProgress in neonatal medicine has dramatically improved the survival rate of preterm births, but the evidence suggests that these low-birth weight infants (LBWIs) go on to develop pervasive development disorders and attention deficit hyperactivity disorder (ADHD) at greater rates than the general population. Children with neurodevelopmental disorders are known to suffer from deficits in visual cognition, such as in face perception and attentional functions, the characteristics of which already manifest in early infancy.PurposeThis study aimed to investigate visual cognition in LBWIs during infancy.Subjects20 LBWIs and 20 normal-birth-weight infants (NBWIs: control) of age 9–10 months (corrected age was used for LBWIs).MethodChildren were held seated in front of an eye tracking system by a parent, and presented with facial photos as visual stimuli. During the familiarization phase, the child was presented with two images of the same human face (familiarization stimulus) on the left and right side of a display screen (5 × 10 s trials). Next, during the test phase, the child was presented with the same image on one side of the screen, and a photo of a different person’s face (novel stimulus) on the other (2 × 5 s trials). Gaze behavior was assessed in terms of the total time spent looking at either facial stimulus, and specifically at the eyes of the stimuli, as well as the number of attentional shifts between stimuli, and novelty preference.Results/DiscussionLBWIs spent significant less time looking at facial stimuli overall, and less time at the eye region, than NBWIs. These findings seem to evidence developmental differences in functions related to visual cognition.  相似文献   
107.
European Journal of Clinical Microbiology & Infectious Diseases - The aim of this study is to clarify the characteristics of gram-negative bacteremia (GNB), including extended-spectrum...  相似文献   
108.
Dedifferentiated liposarcoma (DDLPS) is a relatively common soft tissue sarcoma that results from the progression of well‐differentiated liposarcoma (WDLPS). This study aimed to investigate the progression process and to clarify the pathological and genetic factors related to poor prognosis in DDLPS. In 32 DDLPS cases and five WDLPS cases, genetic factors were analyzed by custom comparative genomic hybridization (CGH) array, which was designed to densely cover gene regions known to be frequently amplified in WD/DDLPS. The analyses comparing primary and metastatic lesions and those comparing histologically different areas in the same tumor revealed intra‐tumoral genetic heterogeneity and progression. According to a prognostic analysis comparing the good‐prognosis and the poor‐prognosis groups, we selected MDM2 and HMGA2 as candidate genes associated with poor and good prognosis, respectively. The ratios of the amplification or gain levels of MDM2 and HMGA2 expressed in log ratios (log[MDM2/HMGA2] = log[MDM2]‐log[HMGA2]) were significantly associated with prognosis. An amplification or gain level of MDM2 that was more than twice that of HMGA2 (MDM2/HMGA2 > 2, log[MDM2/HMGA2] > 1) was strongly related to poor OS (P < .001) and poor distant metastasis‐free survival (DMFS) (P < .001). In the pathological analysis of 44 cases of DDLPS, histological tumor grade, cellular atypia, and MDM2 immunoreactivity were related to overall survival (OS), while HMGA2 immunoreactivity tended to be associated with OS. Cellular atypia was also associated with DMFS. In conclusion, histological grade and MDM2 expression were determined to be prognostically important, and the MDM2/HMGA2 amplification or gain ratio was found to have significant prognostic value by the custom CGH array analysis.  相似文献   
109.
Journal of Artificial Organs - This work investigates the plasma skimming effect in a spiral groove bearing within a hydrodynamically levitated centrifugal blood pump when working with human blood...  相似文献   
110.
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