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   3431篇
  免费   120篇
  国内免费   14篇
耳鼻咽喉   39篇
儿科学   126篇
妇产科学   24篇
基础医学   379篇
口腔科学   41篇
临床医学   188篇
内科学   831篇
皮肤病学   65篇
神经病学   274篇
特种医学   177篇
外科学   549篇
综合类   18篇
预防医学   152篇
眼科学   75篇
药学   265篇
中国医学   4篇
肿瘤学   358篇
  2022年   32篇
  2021年   47篇
  2020年   31篇
  2019年   29篇
  2018年   48篇
  2017年   27篇
  2016年   61篇
  2015年   45篇
  2014年   76篇
  2013年   98篇
  2012年   161篇
  2011年   205篇
  2010年   111篇
  2009年   114篇
  2008年   191篇
  2007年   190篇
  2006年   182篇
  2005年   228篇
  2004年   226篇
  2003年   204篇
  2002年   217篇
  2001年   55篇
  2000年   33篇
  1999年   54篇
  1998年   50篇
  1997年   65篇
  1996年   59篇
  1995年   57篇
  1994年   49篇
  1993年   48篇
  1992年   48篇
  1991年   42篇
  1990年   29篇
  1989年   38篇
  1988年   38篇
  1987年   16篇
  1986年   30篇
  1985年   31篇
  1984年   33篇
  1983年   20篇
  1982年   16篇
  1981年   16篇
  1980年   15篇
  1979年   10篇
  1978年   19篇
  1975年   9篇
  1957年   23篇
  1956年   16篇
  1955年   17篇
  1954年   11篇
排序方式: 共有3565条查询结果,搜索用时 14 毫秒
991.
992.
The movement of the carpal bones in gripping was clarified in the giant panda ( Ailuropoda melanoleuca ) by means of macroscopic anatomy, computed tomography (CT) and related 3-dimensional (3-D) volume rendering techniques. In the gripping action, 3-D CT images demonstrated that the radial and 4th carpal bones largely rotate or flex to the radial and ulnar sides respectively. This indicates that these carpal bones on both sides enable the panda to flex the palm from the forearm and to grasp objects by the manipulation mechanism that includes the radial sesamoid. In the macroscopic observations, we found that the smooth articulation surfaces are enlarged between the radial carpal and the radius on the radial side, and between the 4th and ulnar carpals on the ulnar side. The panda skilfully grasps using a double pincer-like apparatus with the huge radial sesamoid and accessory carpal.  相似文献   
993.
Osteosarcoma is the most frequent malignant bone tumor in children. It is highly invasive, however, the mechanisms behind osteosarcoma cell invasion are as yet still unknown. In the present study, treatment with TNFα enhanced the invasiveness of two human osteosarcoma cell lines, OST and MNNG. TNFα treatment also induced tumor cell motility, adhesion to laminin, the expression of matrix metalloproteinase 9 (MMP9), and the nuclear translocation of nuclear factor κB (NFκB) in the osteosarcoma cells. Moreover, antioxidants inhibited TNFα-induced osteosarcoma cell invasion, motility and NFκB nuclear translocation, but not adhesion to laminin or MMP9 expression. NFκB decoy, another NFκB inhibitor, also inhibited TNFα-induced osteosarcoma cell invasion and motility. Therefore, motility and NFκB activation were possibly related to TNFα-induced osteosarcoma cell invasion. However, adhesion to laminin or MMP did not demonstrate any correlation with TNFα-induced osteosarcoma cell invasion. Although NFκB is known to regulate TNFα-induced phenotypes, it may influence only motility and invasion, but not the MMP or laminin-mediated adhesion of these osteosarcoma cells. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
994.
Cell migration is important in the development of atherosclerotic lesions. Macrophages and smooth muscle cells migrate into the subendothelial space of arteries, leading to plaque formation. Long-term inhibition of the activity of Rho-kinase induces a regression of atherosclerotic coronary lesions, probably by preventing migration of macrophages and smooth muscle cells. Previous reports concerning the effect of Rho-kinase inhibitors on cell migration are contradictory, however. We examined here the cell type specificity of Rho-kinase inhibitors and found that migration of endothelial cells, macrophages, and smooth muscle cells was inhibited by treatment with Rho-kinase inhibitors in a dose-dependent fashion in a three-dimensional migration assay, whereas that of fibroblasts and epithelial cells was not inhibited. Myosin II inhibitor prevented cell migration in a manner similar to Rho-kinase inhibitors. In contrast, in a two-dimensional migration assay, cell migration was not inhibited by Rho-kinase or myosin II inhibitors for any of the cell types examined. Taken together, these results indicate that Rho-kinase inhibitors suppress migration of specific cell types under specific conditions through the regulation of myosin II activity. Our findings suggest that Rho-kinase is the therapeutic target of atherosclerosis accompanied with invasion by leukocytes and smooth muscle cells.  相似文献   
995.
SUMMARY: As human papillomavirus (HPV) infection is the main risk factor for squamous cell carcinoma of the cervix and overexpression of p16INK4a occurs when retinoblastoma protein is inactivated by high-risk HPV, the authors studied the association of HPV infection and expression of p16INK4a in cervical adenocarcinomas. Specimens of cervical glandular neoplasias were immunostained with a p16INK4a-specific monoclonal antibody (clone E6H4). Approximately 80% of glandular neoplasms showed overexpression of p16INK4a. Exfoliated cells from 14 adenocarcinomas were further examined by p16INK4a-specific immunocytochemistry, and 12 cases showed overexpression of p16INK4a, suggesting that immunostaining for p16INK4a may be a useful diagnostic tool for cervical adenocarcinomas. The authors further examined HPV DNA in cervical adenocarcinomas with the polymerase chain reaction method. Overexpression of p16INK4a was positive in 94% of cases in which HPV16 or 18DNA was positive, a finding suggesting that HPV16 or 18 may play an important role in cervical adenocarcinomas. Overexpression of p16INK4a may be an indicator of pathogenic activity of high-risk HPVs.  相似文献   
996.
997.
Rabies has almost a 100% case-fatality rate and kills more than 59,000 people annually around the world. There is no established treatment for rabies. The rabies virus (RABV) expresses only the glycoprotein (RABVG) at the viral surface, and it is the target for the neutralizing antibodies. We previously established mouse monoclonal antibodies, 15–13 and 12–22, which showed neutralizing activity against the RABV, targeting the sequential and conformational epitopes on the RABVG, respectively. However, the molecular basis for the neutralizing activity of these antibodies is not yet fully understood. In this study, we evaluated the binding characteristics of the Fab fragments of the 15–13 and 12–22 antibodies. The recombinant RABVG protein, in prefusion form for the binding analysis, was prepared by the silkworm–baculovirus expression system. Biolayer interferometry (BLI) analysis indicated that the 15–13 Fab interacts with the RABVG, with a KD value at the nM level, and that the 12–22 Fab has a weaker binding affinity (KD ~ μM) with the RABVG compared to the 15–13 Fab. Furthermore, we determined the amino acid sequences of both the antibodies and the designed single-chain Fv fragments (scFvs) of the 15–13 and 12–22 antibodies as another potential biopharmaceutical for targeting rabies. The 15–13 and 12–22 scFvs were successfully prepared by the refolding method and were shown to interact with the RABVG at the nM level and the μM level of the KD, respectively. These binding characteristics were similar to that of each Fab. On the other hand, differential scanning fluorometry (DSF) revealed that the thermal stability of these scFvs decreases compared to their Fabs. While the improvement of the stability of scFvs will still be required, these results provide insights into the neutralizing activity and the potential therapeutic use of antibody fragments for RABV infection.  相似文献   
998.
Smoking prevalence remains high (around 60%) among Japanese males, but smoking initiation among males born in the 1930s decreased by approximately 10% due to economic difficulties following World War II. The present study was designed to examine whether this temporary decline in smoking initiation influenced the subsequent incidence of lung cancers, especially adenocarcinoma. Trends of lung cancer incidence by histological type in both sexes were investigated using data from the population-based cancer registry in Nagasaki, Japan, from 1986 through 1995. During this period, 5668 males and 2309 females were diagnosed as having lung cancer, and the overall incidence of lung cancers among both sexes remained stable. However, males aged 55–59 years showed a decrease in the age-specific incidence of adenocarcinoma and squamous-cell carcinoma ( P < 0.05 and P < 0.01, respectively). In birth cohort analyses, the incidence of adenocarcinoma and squamous-cell carcinoma was lower in the 1935–1939 birth male cohort than in the successive cohorts. The incidence of lung cancers among females with low smoking prevalence did not change with birth cohort. The low smoking initiation among the 1935–1939 birth male cohort appeared to have resulted in a decreased incidence of adenocarcinoma and squamous cell carcinoma among middle-aged Japanese males. The present study suggests that smoking prevention has an effect in reducing the incidence of lung adenocarcinoma, as well as squamous-cell carcinoma, among smokers.  相似文献   
999.
We report two adult Japanese sisters with l-2-hydroxyglutaric aciduria (acidemia), both of whom were much older (aged 57, 47 years old) than previously reported patients (from neonate to 44 years old), and who presented with differing severity. Magnetic resonance imaging revealed typical subcortical white matter lesions in both cases and showed brainstem atrophy and thickness of the calvarium in the elder sister. l-2-Hydroxyglutaric acid levels were increased in urine, plasma, and cerebrospinal fluid. These cases suggest that organic acid analysis is necessary even in elderly patients who seem to have neurodegenerative disorders. Received: 6 May 1998 Received in revised form: 11 August 1998 Accepted: 5 October 1998  相似文献   
1000.
A 49-year-old man, who had a 3-year history of liver dysfunction but had not been treated, was admitted to the hospital with a sudden onset of fever and generalized muscle pain. He subsequently developed generalized purpura with scattered hemorrhagic bullae of the skin and massive bloody stools. Aeromonas sobria was proven by culture of both blood and bullous fluid. In spite of the extensive treatment with antibiotics and other medications in the intensive care unit (ICU), the patient went into septic shock and died 2 days after admission. Pathological examination on autopsy revealed segmental necrotizing gastroenteritis with bacterial colonies and alcoholic liver cirrhosis, in addition to extensive severe soft tissue damage involving cellulitis and rhabdomyolysis and epidermolysis. Although the prognosis for Vibrio vulnificus infection with severe soft tissue damage in patients with liver cirrhosis, malignancy, diabetes mellitus or other pre-existing diseases is poor, the unfavorable progression of Aeromonas species, especially A. sobria infection is rare. This is thought to be the first report of an autopsied case.  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