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   2632篇
  免费   204篇
  国内免费   5篇
耳鼻咽喉   27篇
儿科学   107篇
妇产科学   21篇
基础医学   353篇
口腔科学   39篇
临床医学   265篇
内科学   370篇
皮肤病学   33篇
神经病学   286篇
特种医学   215篇
外国民族医学   1篇
外科学   358篇
综合类   86篇
一般理论   1篇
预防医学   274篇
眼科学   8篇
药学   196篇
中国医学   3篇
肿瘤学   198篇
  2022年   28篇
  2021年   45篇
  2020年   26篇
  2019年   40篇
  2018年   51篇
  2017年   37篇
  2016年   58篇
  2015年   70篇
  2014年   66篇
  2013年   112篇
  2012年   108篇
  2011年   89篇
  2010年   53篇
  2009年   60篇
  2008年   109篇
  2007年   120篇
  2006年   106篇
  2005年   88篇
  2004年   83篇
  2003年   82篇
  2002年   92篇
  2001年   80篇
  2000年   70篇
  1999年   68篇
  1998年   48篇
  1997年   35篇
  1996年   25篇
  1995年   44篇
  1994年   33篇
  1993年   42篇
  1992年   69篇
  1991年   64篇
  1990年   60篇
  1989年   41篇
  1988年   55篇
  1987年   49篇
  1986年   63篇
  1985年   38篇
  1984年   43篇
  1983年   39篇
  1982年   27篇
  1981年   25篇
  1980年   21篇
  1979年   28篇
  1978年   15篇
  1977年   19篇
  1976年   16篇
  1974年   25篇
  1973年   17篇
  1971年   15篇
排序方式: 共有2841条查询结果,搜索用时 15 毫秒
81.
European Child & Adolescent Psychiatry - The Strengths and Difficulties Questionnaire (SDQ) is widely used, based on evidence of its value for screening. This evidence primarily regards the...  相似文献   
82.
Embryonic stem (ES) cells can generate neural progenitors and neurons in vitro and incorporate into the adult central nervous system (CNS) following transplantation, suggesting their therapeutic potential for treating neurological disorders. However, our understanding of the conditions that direct ES-derived neural progenitor (ESNP) migration and differentiation within different regions of the adult CNS is incomplete. Rodents treated with the chemoconvulsant kainic acid (KA) experience seizures and display hippocampal sclerosis, as well as enhanced hippocampal neurogenesis, similar to pathological findings in patients with temporal lobe epilepsy (TLE). To examine the potential for ESNPs to incorporate into the adult hippocampus and differentiate into hippocampal neurons or glia following seizure-induced damage, we compared the fates of ESNPs after they were transplanted into the CA3 region or fimbria 1 week following KA-induced seizures. After 4-8 weeks, ESNPs grafted into the CA3 region had migrated to the dentate gyrus (DG), where a small subset adopted neural stem cell fates and continued to proliferate, based on bromodeoxyuridine uptake. Others differentiated into neuroblasts or dentate granule neurons. In contrast, most ESNPs transplanted into the fimbria migrated extensively along existing fiber tracts and differentiated into oligodendrocytes or astrocytes. Hippocampal grafts in mice not subjected to seizures displayed a marked tendency to form tumors, and this effect was more pronounced in the DG than in the fimbria. Taken together, these data suggest that seizures induce molecular changes in the CA3 region and DG that promote region-specific neural differentiation and suppress tumor formation.  相似文献   
83.
84.
85.
86.

Purpose  

In this study, two unreported estrogen antagonists were identified using a combination of computational screening and a simple bacterial estrogen sensor.  相似文献   
87.
A case of congenital pancreatic cysts detected antenatally by ultrasound is presented. This is the second case detected antenatally. Congenital pancreatic cysts should be included in the differential diagnosis of upper abdominal cystic masses in the fetus and newborn infant.  相似文献   
88.
The first case of a patient with interrupted inferior vena cava, four post-renal veins and an azygoshemiazygos continuation is presented. The complicated anomalies were omphalocele and atrial septal defect. Cine-magnetic resonance imaging and cardiac catheterization showed an anomalous retroaortic left innominate vein, azygos-hemiazygos continuation in the prerenal portion, arch formed renal vein in the renal portion and four embryonic vessels in the post-renal portion. Combination of these anomalies in the major venous system suggested that the inferior vena cava had failed to form and that the bilateral embryonic venous system, postcardinal and supracardinal veins persisted to be the systemic venous channels.  相似文献   
89.
Mutations in the TP53 tumor suppressor gene have been studied in different types of brain tumors. Little is known about this genetic event in human meningioma, a mostly benign tumor. To investigate the frequency of TP53 gene mutations in human tumors derived from meningeal tissues, paraffin-embedded tissues from 30 cases (including 2 malignant and 4 atypical meningiomas, as well as 2 hemangioblastomas and 3 hemangiopericytomas) were screened by immunohistochemistry. Polymerase chain reaction/single strand conformational polymorphism (PCR/SSCP) and direct DNA sequencing were thereafter performed in selected cases. Nuclear p53 staining was not seen in any of the 19 benign meningiomas tested, while atypical meningiomas, hemangioblastomas, and hemangiopericytomas displayed nuclear staining in a subpopulation of tumor cells in 4 out of 5, 2 out of 2, and 3 out of 3 cases, respectively. One malignant meningioma showed an intense nuclear staining and a band shift in SSCP. In this case, we identified a mutation in the TP53 gene at codon 161 changing GCC to ACC and resulting in an alteration of alanine to threonine in this position. Our results indicate that TP53 gene mutation may be considered as a marker for malignant transformation in meningioma. p53 immunoreactivity, even in the absence of detectable gene mutation, is also associated with atypia and does not appear in regular benign meningiomas. © 1995 Wiley-Liss, Inc.  相似文献   
90.
Rofecoxib is a highly active and selective cyclo-oxygenase II inhibitor. A stability-indicating method for the assay of rofecoxib has been developed using reverse-phase high-performance liquid chromatography (HPLC). Stress testing of rofecoxib was conducted during the method development and validation. HPLC analysis of rofecoxib solutions stressed under alkaline and photolytic conditions revealed the presence of several degradates. Two main degradates were determined to be the cyclization product formed by photo-cyclization and the dicarboxylate formed by ring opening in the presence of base and oxygen. The identities of these degradates were confirmed by comparison of UV spectra and HPLC retention time with the independently synthesized products. The mechanistic pathways for the formation of these degradates are discussed. Further improvement of the HPLC method's ruggedness has been made based on these studies.  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