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   996篇
  免费   75篇
  国内免费   1篇
耳鼻咽喉   12篇
儿科学   35篇
妇产科学   13篇
基础医学   199篇
口腔科学   10篇
临床医学   116篇
内科学   158篇
皮肤病学   9篇
神经病学   70篇
特种医学   71篇
外科学   116篇
综合类   3篇
预防医学   37篇
眼科学   33篇
药学   140篇
肿瘤学   50篇
  2021年   16篇
  2020年   8篇
  2019年   7篇
  2018年   12篇
  2017年   12篇
  2016年   16篇
  2015年   16篇
  2014年   27篇
  2013年   28篇
  2012年   52篇
  2011年   43篇
  2010年   18篇
  2009年   18篇
  2008年   35篇
  2007年   39篇
  2006年   41篇
  2005年   35篇
  2004年   52篇
  2003年   41篇
  2002年   48篇
  2001年   51篇
  2000年   48篇
  1999年   46篇
  1998年   22篇
  1997年   7篇
  1996年   14篇
  1995年   6篇
  1992年   15篇
  1991年   10篇
  1990年   10篇
  1989年   13篇
  1988年   12篇
  1987年   13篇
  1986年   7篇
  1985年   8篇
  1983年   9篇
  1979年   7篇
  1978年   6篇
  1977年   7篇
  1973年   8篇
  1972年   15篇
  1971年   9篇
  1967年   10篇
  1954年   8篇
  1949年   7篇
  1940年   6篇
  1939年   8篇
  1938年   7篇
  1937年   6篇
  1936年   6篇
排序方式: 共有1072条查询结果,搜索用时 15 毫秒
1.
Polyploidization and centrosome hyperamplification in inflammatory bronchi   总被引:1,自引:0,他引:1  
OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi.  相似文献   
2.
3.
M E Eichler  K M Rich 《Brain research》1989,482(2):340-346
The time course of dependence on nerve growth factor (NGF) for survival in sensory neurons in vitro was examined with microscopic and biochemical methods. Primary dorsal root ganglion (DRG) cultures from embryonic-day-15 (E-15) and day-19 (E-19) rats were maintained with standard dissociated cell culture techniques in the absence of most non-neuronal cells. After various times in culture, neurons were acutely deprived of neurotrophic support by changing to NGF-free medium and adding NGF antiserum to eliminate any residual NGF. Neuronal cultures were examined with phase microscopy; and, their metabolic activity was measured with a protein assay at various time points after NGF deprivation. E-15 neurons grown in culture for 5 days were exquisitely sensitive to acute NGF deprivation. By 12 h after NGF deprivation, neuronal morphology was severely disrupted and the majority of neurons appeared dead. E-15 neurons grown in culture for 8 or 11 days showed progressively less dependence on NGF for survival. These older neurons did not die until 24 and 48 h, respectively, following NGF withdrawal. Neurons grown in culture for 20 days did not show any morphologic changes by phase microscopy up to 4 days after NGF deprivation. Protein incorporation progressively decreased between 12 and 48 h after NGF withdrawal in E-15 neurons grown in culture for 5, 8, or 11 days.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
4.
5.
Eosinophilic activation in cystic fibrosis.   总被引:1,自引:1,他引:0       下载免费PDF全文
D Y Koller  M Gtz  I Eichler    R Urbanek 《Thorax》1994,49(5):496-499
BACKGROUND--The neutrophil is a potent contributor to pulmonary destruction in cystic fibrosis. Since eosinophils also possess destructive potential the involvement of eosinophils in cystic fibrosis has been investigated. METHODS--Eosinophil numbers and levels of eosinophil cationic protein (ECP), a marker of eosinophil activation, were determined in the serum of 42 patients with cystic fibrosis and in the sputum of 10 of them. To determine neutrophil activation levels of myeloperoxidase (MPO) were also measured. RESULTS--In cystic fibrosis increased serum levels of ECP were detected compared with healthy non-atopic subjects. Serum ECP levels were not related to the peripheral blood eosinophil count. A strong correlation with ECP concentrations in sputum indicated that the level of ECP in serum was representative of its pulmonary level. Levels of MPO were also increased in cystic fibrosis. A strong correlation was found between MPO and pulmonary function. In addition, ECP was related to arterial oxygen and carbon dioxide tensions. Antibiotic treatment reduced neutrophil activation without effect on ECP levels. CONCLUSIONS--Until now Pseudomonas aeruginosa and neutrophils were held to be primarily responsible for progressive tissue damage in cystic fibrosis. The results of this study suggest that eosinophils might also participate in such pulmonary destruction.  相似文献   
6.
7.
Echographic follow-up examinations were performed in 72 patients in whom a choroidal melanoma was treated with (106Ru/106Rh) applicators. The observation period was between 6 and 15 months. Echographic measurement of tumor prominence and assessment of the degree of reflection proved to be important indicators for judging the success of beta radiation therapy. If the prominence diminishes and the degree of reflection increases after treatment, regression of the tumor may safely be assumed to have occurred. Apart from an increase in the prominence of the tumor, a constantly low or even falling level of reflection are signs of a less favorable prognosis.  相似文献   
8.
9.
10.
Zusammenfassung Aus mitteleuropäischen Singvögeln werden die folgenden neuen Menacanthus-Arten beschrieben: M. festivus nov. spec. von Fringilla coelebs, M. pius nov. spec. von Turdus merula, M. polonicus nov. spec. von Turdus pilaris, M. vistulanus nov. spec. von Sylvia borin und M. wipszyckii nov. spec. von Chloris chloris. Die Tatsache, daß das insgesamt aus mehreren Funden und besonders für M. pius nov. spec. aus zahlreichen Exemplaren bestehende, dieser Arbeit zugrunde liegende Untersuchungsmaterial fast ausschließlich Weibchen enthält, wird als Ausgangspunkt für eine Diskussion des Speziesbegriffs bei uniparentalen Mallophagenarten herangezogen. Zur Klärung dieser auch evolutionstheoretisch bemerkenswerten Problematik wird ein Forschungsprogramm für Menacanthus-Arten entwickelt.Mit 10 Textabbildungen  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