全文获取类型
收费全文 | 2121篇 |
免费 | 222篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 80篇 |
妇产科学 | 26篇 |
基础医学 | 301篇 |
口腔科学 | 36篇 |
临床医学 | 212篇 |
内科学 | 540篇 |
皮肤病学 | 31篇 |
神经病学 | 211篇 |
特种医学 | 133篇 |
外科学 | 169篇 |
综合类 | 55篇 |
一般理论 | 1篇 |
预防医学 | 133篇 |
眼科学 | 64篇 |
药学 | 71篇 |
中国医学 | 2篇 |
肿瘤学 | 262篇 |
出版年
2021年 | 26篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 19篇 |
2015年 | 24篇 |
2014年 | 30篇 |
2013年 | 60篇 |
2012年 | 83篇 |
2011年 | 80篇 |
2010年 | 52篇 |
2009年 | 45篇 |
2008年 | 71篇 |
2007年 | 84篇 |
2006年 | 74篇 |
2005年 | 76篇 |
2004年 | 74篇 |
2003年 | 92篇 |
2002年 | 72篇 |
2001年 | 65篇 |
2000年 | 63篇 |
1999年 | 65篇 |
1998年 | 31篇 |
1997年 | 23篇 |
1996年 | 27篇 |
1995年 | 17篇 |
1994年 | 31篇 |
1993年 | 16篇 |
1992年 | 51篇 |
1991年 | 46篇 |
1990年 | 43篇 |
1989年 | 44篇 |
1988年 | 56篇 |
1987年 | 68篇 |
1986年 | 64篇 |
1985年 | 67篇 |
1984年 | 40篇 |
1983年 | 43篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1980年 | 30篇 |
1979年 | 42篇 |
1978年 | 28篇 |
1977年 | 33篇 |
1976年 | 19篇 |
1975年 | 25篇 |
1974年 | 34篇 |
1973年 | 31篇 |
1972年 | 28篇 |
1971年 | 14篇 |
1969年 | 20篇 |
排序方式: 共有2344条查询结果,搜索用时 31 毫秒
41.
Teipel SJ Hampel H Pietrini P Alexander GE Horwitz B Daley E Möller HJ Schapiro MB Rapoport SI 《Archives of neurology》1999,56(4):467-473
BACKGROUND: Positron emission tomographic studies of patients with Alzheimer disease (AD) suggest a loss of metabolic functional interactions between different cortical regions. Atrophy of the corpus callosum as the major tract of intracortical connective fibers may reflect decreased cortical functional integration in AD. OBJECTIVES: To investigate whether regional atrophy of the corpus callosum is correlated with regional reductions of cortical glucose metabolism, as shown by positron emission tomography, and whether primary white matter degeneration is a possible cofactor of corpus callosum atrophy in AD. PATIENTS AND METHODS: We measured total and regional cross-sectional areas of the corpus callosum on midsagittal magnetic resonance imaging scans from 12 patients with AD and 15 age-matched control subjects. Regional cerebral metabolic rates for glucose in cortical lobes were measured by positron emission tomography using fludeoxyglucose F 18. White matter hyperintensities were rated in T2-weighted magnetic resonance imaging scans. RESULTS: The total cross-sectional area of corpus callosum was significantly reduced in patients with AD, with the most prominent changes in the rostrum and splenium and relative sparing of the body of the corpus callosum. Frontal and parietal lobe metabolism was correlated with the truncal area of the corpus callosum in AD. The ratios of frontal to parietal and of frontal to occipital metabolism were correlated with the ratio of anterior to posterior corpus callosum area in the group with AD. White matter hyperintensities did not correlate with corpus callosum atrophy in the patients with AD. CONCLUSION: The regional pattern of corpus callosum atrophy correlated with reduced regional glucose metabolism independently of primary white matter degeneration in the patients with AD. 相似文献
42.
43.
44.
The activity of N-acetyl galactosamine-6-sulfate sulfatase was studied for the first time in the liver and brain of a patient with a clinically typical case of Morquio syndrome with keratosulfaturia. As has been demonstrated in the fibroblasts of patients with this syndrome, this enzymatic activity was markedly decreased in both organs. Neuropathological examination revealed moderately swollen neurons containing PAS-positive, coarse globular inclusions in the cerebral cortex, Ammon's horn, basal ganglia, and thalamic nuclei. Ultrastructurally, the inclusions consisted of stacked, straight or loose, wavy membranes of various lengths, often associated with pale or moderately electron dense homogeneous "lipid droplets." These ultrastructural features of the inclusions were closely similar to the granulomembranous bodies of Hurler syndrome and the inclusions described in type B of the Sanfilippo syndrome. Unlike those mucopolysaccharidoses, however, no abnormalities were found in the gangliosides in the brain of the patient with Morquio syndrome. 相似文献
45.
Kernan WN Viscoli CM Brass LM Makuch RW Sarrel PM Horwitz RI 《Stroke; a journal of cerebral circulation》2000,31(2):415-419
BACKGROUND AND PURPOSE: After a transient ischemic attack or stroke, the risk for recurrence may be reduced by treatment of hypertension. The purpose of this study was to determine how commonly blood pressure exceeds national guidelines among patients who have had one of these events. METHODS: Subjects were 644 women participating in a randomized trial of estrogen for secondary stroke prevention. We measured blood pressure 1 month after the stroke or TIA while patients were under the care of their personal physicians. Among 536 patients, a second measure was made at an average of 2.9 years after the first. RESULTS: The mean age of participants was 71 years, and 73% reported a history of hypertension. At baseline, only 44% (280/644) of the women had blood pressure values within national guidelines (<140/90 mm Hg). With separate guidelines used for diabetics (<130/85 mm Hg) and nondiabetics (<140/90 mm Hg), the proportions of women within the guidelines were 27% and 44%, respectively. Overall, 39% of patients were within the diabetes-adjusted guidelines. Among patients whose blood pressure exceeded 140/90 mm Hg at first examination, 55% were still in excess at follow-up. Features associated with severe hypertension at first examination (>160/100 mm Hg) were history of hypertension, education less than college, and higher cognitive functioning. CONCLUSIONS: Blood pressure values in excess of national guidelines are common after stroke and TIA, especially among diabetic patients. Efforts to lower blood pressure control may enhance secondary prevention. 相似文献
46.
A S Garden J Harris E E Vokes A A Forastiere J A Ridge C Jones E M Horwitz B S Glisson L Nabell J S Cooper W Demas E Gore 《Journal of clinical oncology》2004,22(14):2856-2864
PURPOSE: To define further the role of concurrent chemoradiotherapy for patients with advanced squamous carcinoma of the head and neck. PATIENTS AND METHODS: The Radiation Therapy Oncology Group developed this three-arm randomized phase II trial. Patients with stage III or IV squamous carcinoma of the oral cavity, oropharynx, or hypopharynx were eligible. Each of three arms proposed a radiation schedule of 70 Gy in 35 fractions. Patients on arm 1 were to receive cisplatin 10 mg/m(2) daily and fluorouracil (FU) 400 mg/m(2) continuous infusion (CI) daily for the final 10 days of treatment. Treatment on arm 2 consisted of hydroxyurea 1 g every 12 hours and FU 800 mg/m(2)/d CI delivered with each fraction of radiation. Arm 3 patients were to receive weekly paclitaxel 30 mg/m(2) and cisplatin 20 mg/m(2). Patients randomly assigned to arms 1 and 3 were to receive their treatments every week; patients on arm 2 were to receive their therapy every other week. RESULTS: Between 1997 and 1999, 241 patients were entered onto study; 231 were analyzable. Ninety-two percent, 79%, and 83% of patients on arms 1, 2, and 3, respectively, were able to complete their radiation as planned or with an acceptable variation. Fewer than 10% of patients had unacceptable deviations or incomplete chemotherapy in the three arms. Estimated 2-year disease-free and overall survival rates were 38.2% and 57.4% for arm 1, 48.6% and 69.4% for arm 2, and 51.3% and 66.6% for arm 3. CONCLUSION: We have demonstrated that three different approaches of concurrent multiagent chemotherapy and radiation were feasible and could be delivered to patients in a multi-institutional setting with high compliance rates. 相似文献
47.
Gerald E Hanks Thomas F Pajak Arthur Porter David Grignon Harmart Brereton Varagur Venkatesan Eric M Horwitz Colleen Lawton Seth A Rosenthal Howard M Sandler William U Shipley 《Journal of clinical oncology》2003,21(21):3972-3978
PURPOSE: Radiation Therapy Oncology Group (RTOG) Protocol 92-02 was a randomized trial testing long-term (LT) adjuvant androgen deprivation (AD) after initial AD with external-beam radiotherapy (RT) in patients with locally advanced prostate cancer (PC; T2c-4) and with prostate-specific antigen level less than 150 ng/mL. PATIENTS AND METHODS: Patients received a total of 4 months of goserelin and flutamide, 2 months before and 2 months during RT. A radiation dose of 65 to 70 Gy was given to the prostate and a dose of 44 to 50 Gy to the pelvic lymph nodes. Patients were randomly assigned to receive no additional therapy (short-term [ST]AD-RT) or 24 months of goserelin (LTAD-RT); 1,554 patients were entered onto the study. RESULTS: The LTAD-RT arm showed significant improvement in all efficacy end points except overall survival (OS; 80.0% v 78.5% at 5 years, P =.73), compared with the STAD-RT arm. In a subset of patients not part of the original study design, with tumors assigned Gleason scores of 8 to 10 by the contributing institutions, the LTAD-RT arm had significantly better OS (81.0% v 70.7%, P =.044). There was a small but significant increase in the frequency of late radiation grades 3, 4, and 5 gastrointestinal toxicity ascribed to the LTAD-RT arm (2.6% v 1.2% at 5 years, P =.037), the cause of which is not clear. CONCLUSION: The RTOG 92-02 trial supports the addition of LT adjuvant AD to STAD with RT for T2c-4 PC. In the exploratory subset analysis of patients with Gleason scores 8 to 10, LT adjuvant AD resulted in a survival advantage. 相似文献
48.
49.
WBG Macdonald AP Patrikeos RI Thompson BD Adler AA Van Der Schaaf 《Journal of Medical Imaging and Radiation Oncology》2005,49(1):32-38
The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses. 相似文献
50.
Mitchell E. Horwitz 《Current hematologic malignancy reports》2016,11(1):12-18
The outcome of umbilical cord blood transplantation for adult patients with hematologic malignancies now rivals that of matched unrelated donor transplantation. However, delayed hematopoietic and immunologic recovery remains a source of significant morbidity and mortality. Multiple strategies are now being studied to overcome these limitations. One strategy involves ex vivo expansion of the umbilical cord blood unit prior to transplantation. A second strategy involves exposure of the umbilical cord blood graft to compounds aimed at improving homing and engraftment following transplantation. Such a strategy may also address the problem of slow hematopoietic recovery as well as the increased risk of graft failure. Many of these strategies are now being tested in late phase multi-center clinical trials. If proven cost-effective and efficacious, they may alter the landscape of donor options for allogeneic stem cell transplantation. 相似文献