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   952篇
  免费   70篇
  国内免费   1篇
耳鼻咽喉   9篇
儿科学   33篇
妇产科学   20篇
基础医学   193篇
口腔科学   8篇
临床医学   76篇
内科学   133篇
皮肤病学   41篇
神经病学   47篇
特种医学   52篇
外科学   68篇
综合类   5篇
一般理论   2篇
预防医学   64篇
眼科学   25篇
药学   73篇
中国医学   3篇
肿瘤学   171篇
  2023年   5篇
  2022年   4篇
  2021年   12篇
  2020年   12篇
  2019年   17篇
  2018年   17篇
  2017年   13篇
  2016年   16篇
  2015年   21篇
  2014年   31篇
  2013年   44篇
  2012年   53篇
  2011年   65篇
  2010年   50篇
  2009年   49篇
  2008年   60篇
  2007年   67篇
  2006年   58篇
  2005年   59篇
  2004年   61篇
  2003年   61篇
  2002年   62篇
  2001年   18篇
  2000年   26篇
  1999年   21篇
  1998年   22篇
  1997年   13篇
  1996年   9篇
  1995年   11篇
  1994年   5篇
  1993年   3篇
  1992年   6篇
  1991年   3篇
  1990年   3篇
  1987年   4篇
  1985年   3篇
  1982年   4篇
  1981年   5篇
  1980年   4篇
  1977年   3篇
  1974年   2篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1966年   3篇
  1963年   1篇
  1946年   1篇
  1936年   2篇
  1935年   1篇
  1934年   3篇
排序方式: 共有1023条查询结果,搜索用时 15 毫秒
1.
Summary Background Pregnancy is prossible in female patients who underwent cardiac transplantation but is associated with unpredictable risks. Methods A 23-year old female patient underwent cardiac transplantation because of dilatative cardiomyopathy. Results Against our advice, she became pregnant 4 months after transplantation. Following an uneventful pregnancy, spontaneous vaginal delivery occurred 13 months after transplantation. The patient gave birth to a healthy new-born in good physical condition. Thereafter, the patient refused to attend any further routine follow-up control. 9 months after delivery, the patient was admitted to hospital in severe cardiac shock. Biopsy showed a serious, acute rejection which was treated with a course of methylprednisolone. Clinically, the patient recovered within 1 week, but died from acute myocardial infarction 1 day after discharge from hospital. Conclusions Only women without a history of rejection episodes, with good kidney function, good graft function, and high compliance should be counselled to become pregnant.   相似文献   
2.

Background  

Streptococcus (S.) pneumoniae meningitis has a high lethality despite antibiotic treatment. Inflammation is a major pathogenetic factor, which is unresponsive to antibiotics. Therefore adjunctive therapies with antiinflammatory compounds have been developed. TNF484 is a TNF-alpha converting enzyme (TACE) inhibitor and has been found efficacious in experimental meningitis. Toll-like receptor 2 (TLR2) contributes to host response in pneumococcal meningitis by enhancing bacterial clearing and downmodulating inflammation. In this study, TNF484 was applied in mice, which lacked TLR2 and exhibited a strong meningeal inflammation.  相似文献   
3.
Valproic acid (VPA) is a broad-spectrum antiepileptic drug and is usually well-tolerated. Rare serious complications may occur in some patients, including haemorrhagic pancreatitis, bone marrow suppression, VPA-induced hepatotoxicity and VPA-induced encephalopathy. The typical signs of VPA-induced encephalopathy are impaired consciousness, sometimes marked EEG background slowing, increased seizure frequency, with or without hyperammonemia. There is still no proof of causative effect of VPA in patients with encephalopathy, but only of an association with an assumed causal relation. We report 19 patients with VPA-associated encephalopathy in Germany from the years 1994 to 2003, none of whom had been published previously.  相似文献   
4.
A Null lymphocyte-enriched population was isolated from human peripheral blood of healthy donors using a combination of Ficoll density gradient centrifugation followed by elimination of mononuclear phagocytes, passage through Ig-anti-Ig columns and sedimentation of E rosettes. After each separation step lymphocyte fractions were examined for morphology, cell surface markers, mitogen responsiveness and effector functions in antibody-dependent (ADCC) and spontaneous cellular cytotoxicity (SCMC) reactions against an allogeneic melanoma cell line. The final Null lymphocyte preparation was recovered at a rate of 1 to 3 % from the population passed through Ig-anti-Ig columns (fraction FFF-C). The marker analysis revealed over 99 %of surface Ig-negative lymphoid cells; 50 to 60 % of these cells were ‘real Null’ cells lacking immunological cell surface markers, 7 % formed EA, 13 % EAC and 24 %E rosettes. Regarding the mitogen responses, passage through Ig-anti-Ig columns drastically reduced concanavalin A (Con A), pokeweed mitogen (PWM)and tuberculin (PPD) responses, whereas the phytohemagglutinin (PHA) response was reduced in absolute counts but not in the stimulation index. Compared to the T cell-enriched lymphocyte fraction, the Null cells showed significantly diminished proliferative responses to PHA and Con A and slightly increased reactivity to PWM and PPD. Although depleted of high affinity Fc receptor lymphocytes, the Null cell fractions exhibited good ADCC and SCMC activities being about 4 to 6 times higher than in the T cell fraction.  相似文献   
5.
Summary Five adenovirus 15/Hx and one Ad9/Hx strain with a common novel hemagglutinin were compared serologically and by DNA restriction analysis with six endonucleases with the related prototypes. The five Ad15/Hx strains represented five different genome types.With 1 FigureAided by grants from the Deutsche Forschungsgemeinschaft (Wi 2/21-1), Bundesministerium für Jugend, Familie und Gesundheit, and Förderverein der Deutschen Vereinigung zur Bekämpfung der Viruskrankheiten e. V., FRG.  相似文献   
6.
We employ diffuse optical tomography (DOT) to track treatment progress in a female subject presenting with locally advanced invasive carcinoma of the breast during neoadjuvant chemotherapy. Three-dimensional images of total hemoglobin concentration and scattering identified the tumor. Our measurements reveal tumor shrinkage during the course of chemotherapy, in reasonable agreement with magnetic resonance images of the same subject. A decrease in total hemoglobin concentration contrast between tumor and normal tissue was also observed over time. The results demonstrate the potential of DOT for measuring physiological parameters of breast lesions during chemotherapy.  相似文献   
7.
In head and neck cancer as well as in other carcinomas, tumor expansion and spread to distant sites require the secretion of destructive enzymes that degrade the extracellular matrix. A variety of proteases contribute to matrix destruction. Characteristics of the invasive tumor front may reflect tumor prognosis better than do other parts of the tumor. Therefore, it was the aim of the present study to (i) compare central and peripheral tumor zones for differences in the expression of matrix-metalloproteinases (MMP) -2 and -9 and their naturally occurring inhibitors (tissue inhibitor of matrix-metalloproteinases (TIMP) -1 and -2), (ii) examine the morphological potential of malignancy, and (iii) correlate these findings with clinicopathological parameters. The study population consisted of 106 surgical specimens of advanced head and neck squamous cell carcinomas. The invasive front was graded for malignancy, and immunohistochemical staining with MMP-2, MMP-9, TIMP-1 and TIMP-2 antibodies was performed. Both MMP-2 and MMP-9 were found to be significantly overexpressed at the tumor front. The MMP-2-positive invasive front exhibited diminished overall survival times. In multivariate analysis, MMP-2 expression retained its correlation with overall survival in addition to nodal status and total malignancy score. Expression of TIMP-2 correlated with local tumor invasion. We conclude that the expression of MMP-2 at the invasive front is a marker of poor survival and appears to be associated with early recurrence in initially lymph node-negative patients.  相似文献   
8.
A paradigm for Streptococcus interspecies gene transfer is represented by the mosaic pbp genes encoding the target enzymes for beta-lactam antibiotics, the penicillin-binding proteins, in Streptococcus pneumoniae. We investigated a collection of oral streptococci from three continents by comprehensive multi-locus sequence typing analysis in order to trace the origin of a mosaic block belonging to a dominant family of mosaic pbp2x implicated in penicillin resistance of S. pneumoniae. One widespread family of mosaic pbp2x occurred in all three distinct clusters of S. pneumoniae, Streptococcus mitis and Streptococcus oralis, documenting independent inter- and intraspecies recombination events. Moreover, potential ancestor genes of this mosaic block could be identified in two penicillin-susceptible S. mitis strains from South Africa and Spain, facilitating the identification of pbp2x mutations relevant for resistance development.  相似文献   
9.
The permanent human cell line C3842 was established from a secondary chondrosarcoma in a typical case of Olliers disease. In the present study, we analyzed the morphological, cytogenetic and molecular biological characteristics of the cultured cells in comparison with the original tumor and investigated the invasion properties of the tumor model using functional imaging of proteolysis, matrigel assay and chick chorioallantoic membrane assay. C3842 cells exhibit the typical features of malignant cartilage tumor cells in vitro, including the expression of collagen types II, IX, XI and aggrecan. The proteolytic ability of C3842 cells is attributed to the expression of several proteases, such as cathepsin B, urokinase plasminogen activator and matrix-metalloproteinase-2, which enable the cells to degrade collagen type I and to permeate matrigel matrix. In accordance with the biological features in vivo, C3842 cells are not able to invade through the epithelium of the chick chorioallantoic membrane. In conclusion, the cell line C3842 provides the first model of a secondary chondrosarcoma in Olliers disease in vitro, which is characterized by distinct features of such malignant cartilage tumors.  相似文献   
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