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   626篇
  免费   62篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   21篇
妇产科学   55篇
基础医学   92篇
口腔科学   9篇
临床医学   60篇
内科学   236篇
皮肤病学   4篇
神经病学   34篇
特种医学   59篇
外科学   23篇
综合类   13篇
预防医学   14篇
眼科学   2篇
药学   15篇
中国医学   3篇
肿瘤学   45篇
  2021年   6篇
  2016年   7篇
  2015年   8篇
  2014年   10篇
  2013年   16篇
  2012年   11篇
  2011年   6篇
  2010年   14篇
  2009年   11篇
  2008年   18篇
  2007年   12篇
  2006年   19篇
  2005年   12篇
  2004年   6篇
  2003年   15篇
  2002年   18篇
  2001年   17篇
  2000年   12篇
  1999年   15篇
  1998年   28篇
  1997年   18篇
  1996年   14篇
  1995年   19篇
  1994年   14篇
  1993年   21篇
  1992年   13篇
  1991年   18篇
  1990年   13篇
  1989年   22篇
  1988年   20篇
  1987年   18篇
  1986年   18篇
  1985年   21篇
  1984年   16篇
  1983年   10篇
  1982年   13篇
  1981年   7篇
  1980年   22篇
  1979年   18篇
  1978年   18篇
  1977年   12篇
  1976年   12篇
  1975年   6篇
  1974年   7篇
  1973年   5篇
  1972年   5篇
  1957年   6篇
  1956年   4篇
  1955年   4篇
  1954年   5篇
排序方式: 共有689条查询结果,搜索用时 196 毫秒
51.
OBJECTIVES: The aim of this study was to compare the visual analyses of fetal heart rate tracings by observers according to recent National Institute of Child Health and Human Development interpretative guidelines both with each other and with those of a computerized fetal heart rate analysis and alerting system. STUDY DESIGN: One-hour sections of intrapartum fetal heart rate records were analyzed by a computerized monitoring system (Hewlett-Packard TraceVue; HP GmbH, B?blingen, Germany) and by 4 observers (a registered obstetric nurse, a certified nurse-midwife, an obstetrics resident physician, and a physician maternal-fetal medicine faculty member) instructed to use the new National Institute of Child Health and Human Development guidelines. We compared specific alerts, baseline rates, frequencies of accelerations and decelerations, and signal quality assessments generated by the TraceVue system and the observers. Power analysis indicated that 50 tracings were required to detect interobserver and observer-computer agreement levels of 80% +/- 10%. Statistical comparisons used kappa coefficient, chi(2) test, and analysis of variance with repeated measures as appropriate. RESULTS: Levels of agreement between observer pairs and the computer did not vary significantly across successive 10-minute intervals. Overall levels of interobserver agreement for baseline rate, tracing quality assessment, frequencies of accelerations and decelerations, and alerts ranged from 45% to 99% and were highest for baseline rate and signal loss and lowest for acceleration and deceleration counts. Interobserver agreement for alerts was relatively high (range, 72%-84%), with virtually no difference between any of the observers and the computer (range, 76.9%-79.2%; kappa = 0.25). CONCLUSION: Use of the National Institute of Child Health and Human Development guidelines for visual fetal heart rate interpretation did not increase agreements on most fetal heart rate features beyond those expected by chance or noted in previous reports. These guidelines did appear to blunt some interpretive differences, possibly as a result of observer background. Although levels of agreement on fetal heart rate features differed, agreements on clinical alerts were similar among all observers and a computerized fetal heart rate monitoring system. Computer analysis of fetal heart rate tracings could eliminate interobserver variation that results from visual analysis and could produce more consistent clinical responses to normal and abnormal fetal heart rate patterns.  相似文献   
52.
53.
Five patients at risk for primary central nervous system lymphoma (PCNSL) recurrence were treated with high-dose methylprednisolone (HDMP) to prevent 'trafficking' of malignant lymphocytes into the central nervous system (CNS). HDMP was chosen because of its ability to stabilize the 'blood brain barrier (BBB)'. Three men with newly diagnosed PCNSL, ages 62, 76 and 78y, whose survival was projected to be 6.6 months, began treatment after achieving complete response (CR) to initial radiation therapy alone and survived 27, 37 and 59 months after treatment. In none was death from recurrent disease in CNS but one patient did die of systemic non-Hodgkin's lymphoma (NHL) five years after PCNSL diagnosis. A 20 y old man was treated with HDMP after successful combined modality therapy and is alive 75+ months after initial diagnosis without evidence of disease recurrence. A 34 y old man relapsed after combined modality initial treatment and failed to respond to HDMP when treatment was begun after unsuccessful salvage therapy; he died of disease 12 months after initial diagnosis. There were no treatment complications. The promising results in this pilot study from the basis for a North Central Cancer Treatment Group (NCCTG) 96-73-51, a Phase 2 clinical trial of brain radiotherapy and HDMP for PCNSL patients 70y of age and older, a group of patients at high risk for toxicity from intensive combined modality therapy.  相似文献   
54.
In a 30 month interval at the Los Angeles County-University of Southern California Medical Center, 85 patients had tuboovarian abscesses removed that were unrelated to complications of pregnancy. Thirty-seven patients (44 per cent) of the 85 had unilateral abscesses. Twenty patients (54 per cent) of the 37 patients with a unilateral abscess were using an intrauterine contraceptive device (IUD). In 13 (65 per cent) of the 20 women using an IUD, the foreign body was a Dalkon Shield. Unilateral pelvic abscesses can occur with or without the presence of an IUD.  相似文献   
55.
Lymphangiomas in children: MR imaging   总被引:9,自引:0,他引:9  
Seventeen lymphangiomas in 15 patients were imaged with magnetic resonance (MR) to define the nature, extent, and anatomic relationships of these lesions. The MR and pathologic findings were then compared to determine the histologic basis for the signal-intensity characteristics of these lesions. The signal intensity of 13 lesions was similar to or slightly less than that of muscle on T1-weighted images and greater than that of fat on T2-weighted images. This appearance correlated with the presence of ectatic lymphatic channels containing clear fluid on histologic section. Four lymphangiomas had high signal intensity, approximately equal to that of fat, on T1-weighted images, reflecting the presence of clotted blood or small cystic spaces with a higher ratio of fat to fluid. Sixteen of 17 lesions had visible septations on MR images. The authors' experience suggests that most lymphangiomas have a characteristic appearance on MR images. The information obtained with MR imaging can help in providing a preoperative diagnosis, in planning surgical resection, and in defining recurrence.  相似文献   
56.
Appelman  PT; De Jong  TE; Lampmann  LE 《Radiology》1987,163(3):743-746
In a prospective study, 121 consecutive patients with a clinical diagnosis of deep venous thrombosis of the leg were examined with real-time ultrasonography. The findings were correlated with the results of venography. The common femoral vein and the popliteal vein were evaluated for intraluminal echoes and compressibility, and the common femoral vein was also evaluated for an increase in diameter in response to the Valsalva maneuver. The superficial femoral vein and the calf veins were not evaluated. The results indicate that compressibility of the common femoral and popliteal veins is the best indication of deep venous thrombosis, with a sensitivity of 96% and a specificity of 97%. The accuracy of detection was not improved by including data from thrombus visualization or the response of the common femoral vein to the Valsalva maneuver.  相似文献   
57.
Human T cell leukemia virus (HTLV-II) is an infrequently encountered human T cell leukemia virus first isolated from a patient with atypical hairy cell leukemia. Recently, we identified a second patient infected with HTLV-II who had a similar clinical syndrome of atypical hairy cell leukemia associated with peripheral T cell lymphocytosis. HTLV-II was detected by molecular hybridization studies, and more recently, by electron microscopy, in cell lines derived from the patient. Both patients came from the Los Angeles area and had spent several years in Alaska. As opposed to our two patients, 21 patients with more typical cases of hairy cell leukemia were seronegative for HTLV-II. Two additional cases of unusual T cell malignancy linked to HTLV-II have been described by other investigators and bear limited similarity to our index cases. Further studies are necessary to define the spectrum of malignancies linked to HTLV-II and to identify infected individuals for prospective study.  相似文献   
58.
G C Baldwin  N D Fuller  R L Roberts  D D Ho  D W Golde 《Blood》1989,74(5):1673-1677
Although the control of retroviral disease in animal systems often involves antibody-dependent cell-mediated cytotoxicity (ADCC), the role of cytotoxic function in human retroviral disorders is uncertain. The ability of the neutrophil to kill HIV-infected targets directed by antiviral antibody was examined. Neutrophils from patients with AIDS killed HIV-infected MOLT-3A cells in a manner equivalent to neutrophils obtained from normal volunteers. Both granulocyte- and granulocyte-macrophage colony-stimulating factors (G-CSF and GM-CSF) markedly augmented the cytotoxic function. Studies done with fractionated human antisera revealed that ADCC to HIV-infected cells was mediated only by antibody to the env glycoprotein. ADCC in this system was not dependent on oxidative metabolism because neutrophils from patients with chronic granulomatous disease (CGD) were capable of CSF-augmented cytotoxicity. Although ADCC can be mediated by various classes of lymphocytes and mononuclear phagocytes, such cells may be infected by HIV. Because the neutrophil apparently is not productively infected by the virus, it is an ideal cell to focus on with regard to cytotoxic function in AIDS patients. The findings regarding neutrophil ADCC in AIDS are clinically relevant because the availability of CSFs now permits therapeutic regulation of neutrophils in AIDS patients, and presumably natural antibody may be useful in targeting HIV-infected cells for neutrophil cytotoxicity in vivo.  相似文献   
59.
60.
A monoclonal antibody-secreting hybrid cell line, E7, was constructed from myeloma cells and spleen cells from BALB/c mice immunized with partially purified human MIF from culture fluid of the human T-lymphoblast cell line Mo. The hybrid cell line E7 was selected by screening hybridoma cultures for their capacity to adsorb added MIF activity when assayed together with rabbit anti-mouse IgG-coupled to protein A-Sepharose. The monoclonal antibody produced by the cloned hybridoma E7 also directly neutralized MIF activity from Mo cells and two species of MIF from the culture fluid of human peripheral blood lymphocytes, but did not neutralize IFN-gamma from Mo cells and from human peripheral blood lymphocytes. This antibody reacted also with a component in phytohemagglutinin preparations with an apparent molecular weight of 60,000; however, it did not react with the active tetramer of phytohemagglutinin.  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