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   532篇
  免费   105篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   37篇
妇产科学   10篇
基础医学   80篇
口腔科学   5篇
临床医学   142篇
内科学   79篇
皮肤病学   12篇
神经病学   34篇
特种医学   8篇
外科学   42篇
综合类   6篇
预防医学   49篇
眼科学   72篇
药学   34篇
中国医学   2篇
肿瘤学   24篇
  2024年   1篇
  2023年   3篇
  2022年   4篇
  2021年   18篇
  2020年   10篇
  2019年   11篇
  2018年   17篇
  2017年   13篇
  2016年   7篇
  2015年   18篇
  2014年   16篇
  2013年   29篇
  2012年   46篇
  2011年   50篇
  2010年   29篇
  2009年   21篇
  2008年   70篇
  2007年   112篇
  2006年   29篇
  2005年   23篇
  2004年   28篇
  2003年   21篇
  2002年   21篇
  2001年   5篇
  1999年   4篇
  1998年   3篇
  1997年   7篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   4篇
  1991年   4篇
  1988年   1篇
  1987年   2篇
  1986年   2篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有638条查询结果,搜索用时 15 毫秒
1.
2.
3.
At the present time fine-needle aspiration (FNA) is considered a routine diagnostic procedure in evaluating neoplastic vs. nonneoplastic lesions in many organs, with high sensitivity and specificity. The purpose of this study was to assess the utility of FNA in areas of diagnostic difficulty and its limitations in evaluating bone lesions in patients with a previous history of malignancy. From 1989 to 2000, 249 CT-guided FNAs of bone lesion were performed at our institutions; 187/249 (75.1%) patients had a previous history of malignancy. Aspirated material was air-dried for Diff-Quik stain or fixed in ethanol for Papanicolaou staining. Subsequent surgical tissue was available in 69/187 (36.9%) of the cases. There were 114 males and 73 females, ages 14-86 yr (mean, 64 yr). The primary tumor site was lung 49, genitourinary 46, breast 31, gastrointestinal 28, hematopoietic 26, soft tissue/skin 5, and thyroid 2. There were 125 FNAs of the vertebral spine, 19 from the pelvis, 11 from the ribs, 9 from the sternum, 5 from the femur, and 18 from miscellaneous bone sites. Out of 187, 166 (88.7%) were malignant aspirates confirming the patients' primary malignancies. The most common malignancy encountered was adenocarcinoma, 126/187 (67.4%). Surgical tissue was available for review in 69 patients and the results were in agreement with the FNAs diagnosis in all cases. Nine out of 187 (4.8%) cases were diagnosed as marrow elements on cytological material. These patients have been followed for 1-9 yr and have failed to reveal signs or symptoms of clinical recurrence. Three out of 187 (1.6%) cases showed osteomyelitis. Nine out of 187 (4.8%) were unsatisfactory specimens, with biopsy follow-up available in four cases, showing three metastatic tumors and one case of osteomyelitis. FNA of metastatic bone lesions is a major step in pretreatment diagnosis. On satisfactory specimens, the cytological diagnosis viewed in the clinical-radiological context proves to be similar to surgical diagnosis. FNA is an excellent technique with a high accuracy rate in assessing metastatic bone lesions.  相似文献   
4.
Summary.  A virus isolate causing mosaic disease of commercial sugarcane was purified to homogeneity. Electron microscopy revealed flexuous filamentous virus particles of ca 890 × 15 nm. The virus isolate reacted positively with heterologous antiserum to narcissus latent virus form UK, but failed to react with potyvirus group specific antiserum. N-terminal sequencing of the intact coat protein (CP) and the tryptic peptides indicated that the virus was probably a potyvirus but distinct from several reported potyviruses. Comparison of the 3′-terminal 1084 nucleotide sequence of the RNA genome of this virus revealed 93.6% sequence identity in the coat protein coding region with the recently described sugarcane streak mosaic virus (Pakistani isolate). The molecular weight of the coat protein (40 kDa) was higher than that deduced from the amino acid sequence (34 kDa). The apparent increase in size was shown to be due to glycosylation of the coat protein which has not been reported thus far in the family, Potyviridae. This is the first report on the molecular characterization of a virus causing mosaic disease of sugarcane in India and the results demonstrate that the virus is a strain of sugarcane streak mosaic virus, a member of the Tritimovirus genus of the Potyviridae. We have named it sugarcane streak mosaic virus – Andhra Pradesh isolate (SCSMV-AP). Received October 14, 1997 Accepted August 7, 1998  相似文献   
5.
Capillaria hepatica parasitism   总被引:1,自引:0,他引:1  
Capillaria hepatica is rarely encountered in humans, with fewer than 30 documented cases. The clinico-pathological features of capillaria hepatica infection, diagnosed on liver biopsy of a 6-year-old child are discussed. Pathologically, it is characterised by prominent granulomatous lesions in the liver surrounding the eggs, which on cursory examination may be confused withSchistosoma mansoni.  相似文献   
6.
7.
8.
A 39-year-old healthy woman presented for decreased vision at distance and near for 4 years. She also noted a decrease in her color vision. Her best-corrected visual acuities were 20/70 in each eye. Her visual fields were abnormal, and she had bilateral sluggish pupils, impaired color vision, and optic disc pallor. The magnetic resonance imaging of the brain, heavy metal screen, autoimmune work-up, B12, B6, folate, erythrocyte sedimentation rate, rapid plasma reagin, and Lyme titer were all normal. Optical coherence tomography of the macula and electroretinogram were normal; the visual evoked potential was unrecordable in both eyes. She denied a family history of similar ocular issues, and genotyping of the OPA1 gene revealed a novel previously unreported mutation at IVS12+10T >C.  相似文献   
9.
10.
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