全文获取类型
收费全文 | 3309篇 |
免费 | 253篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 180篇 |
妇产科学 | 57篇 |
基础医学 | 413篇 |
口腔科学 | 174篇 |
临床医学 | 270篇 |
内科学 | 725篇 |
皮肤病学 | 44篇 |
神经病学 | 171篇 |
特种医学 | 380篇 |
外科学 | 299篇 |
综合类 | 37篇 |
一般理论 | 4篇 |
预防医学 | 278篇 |
眼科学 | 34篇 |
药学 | 231篇 |
1篇 | |
中国医学 | 6篇 |
肿瘤学 | 277篇 |
出版年
2022年 | 16篇 |
2021年 | 31篇 |
2020年 | 21篇 |
2019年 | 37篇 |
2018年 | 48篇 |
2017年 | 53篇 |
2016年 | 58篇 |
2015年 | 58篇 |
2014年 | 66篇 |
2013年 | 99篇 |
2012年 | 89篇 |
2011年 | 82篇 |
2010年 | 84篇 |
2009年 | 115篇 |
2008年 | 108篇 |
2007年 | 122篇 |
2006年 | 148篇 |
2005年 | 126篇 |
2004年 | 104篇 |
2003年 | 107篇 |
2002年 | 88篇 |
2001年 | 73篇 |
2000年 | 81篇 |
1999年 | 96篇 |
1998年 | 143篇 |
1997年 | 140篇 |
1996年 | 136篇 |
1995年 | 106篇 |
1994年 | 109篇 |
1993年 | 116篇 |
1992年 | 59篇 |
1991年 | 47篇 |
1990年 | 45篇 |
1989年 | 82篇 |
1988年 | 67篇 |
1987年 | 57篇 |
1986年 | 68篇 |
1985年 | 60篇 |
1984年 | 35篇 |
1983年 | 33篇 |
1982年 | 42篇 |
1981年 | 49篇 |
1980年 | 32篇 |
1979年 | 21篇 |
1978年 | 21篇 |
1977年 | 36篇 |
1976年 | 28篇 |
1975年 | 17篇 |
1972年 | 12篇 |
1969年 | 11篇 |
排序方式: 共有3589条查询结果,搜索用时 15 毫秒
1.
Danielle E Whittier Elizabeth J Samelson Marian T Hannan Lauren A Burt David A Hanley Emmanuel Biver Pawel Szulc Elisabeth Sornay-Rendu Blandine Merle Roland Chapurlat Eric Lespessailles Andy Kin On Wong David Goltzman Sundeep Khosla Serge Ferrari Mary L Bouxsein Douglas P Kiel Steven K Boyd 《Journal of bone and mineral research》2022,37(3):428-439
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR). 相似文献
2.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight. 相似文献
3.
ME BURGE AM JOSHUA CM McNEIL R HUI MJ BOYER R ABRAHAM 《Asia-Pacific Journal of Clinical Oncology》2005,1(1):47-52
Background: Pemetrexed and cisplatin have recently been shown to significantly improve survival compared with cisplatin alone. However, there are only limited data reflecting teaching hospital experience outside a clinical trial. Pemetrexed has only been available in Australia on a restricted basis since 2002. We reviewed our experience of patients treated on the Australian ‘Special Access Scheme’ at three major thoracic oncology units. Methods: Charts were reviewed for all patients enrolled on the scheme. Data was extracted on age, World Health Organization (WHO) performance status, histology, prior therapy, time from diagnosis to starting pemetrexed, chemotherapy (pemetrexed alone or with a platinum), cycle number, response rate, actuarial progression‐free and overall survival. Doses were cisplatin 75 mg/m2 or carboplatin AUC = 5 and pemetrexed 500 mg/m2 every 21 days. Results: 52 patients (32 male and 20 female) were reviewed. Median age was 58 years and 88% were WHO 0–1. Histology included 54% epithelial, 17% biphasic (epithelial and sarcomatoid) and 21% undefined. The median time from diagnosis to administration of pemetrexed was 145 days. Sixty‐five percent had minimal surgical intervention with video assisted thoracoscopy, pleurodesis and biopsy, while 19% had received prior palliative radiation. Seventy‐one percent were chemotherapy naïve, the remaining 29% having received previous platinum and/or gemcitabine regimens. Twenty‐three percent had pemetrexed alone, 35% in combination with carboplatin and 42% with cisplatin. The median number of cycles was 4 (range 1–13). The response rate was 33%. No toxicity was observed in 20% grade 3–4 toxicity in 10% (majority nausea/vomiting). The median progression‐free and overall survival times from starting pemetrexed were 184 days and 298 days, respectively. Conclusions: Pemetrexed‐based regimens are safe and effective in a community setting in malignant mesothelioma. 相似文献
4.
Prevalence of total tooth loss, dental caries, and periodontal disease in Mexican-American adults: results from the southwestern HHANES 总被引:2,自引:0,他引:2
The Southwestern portion of the Hispanic Health and Nutrition Examination Survey (HHANES) was conducted by the National Center for Health Statistics (NCHS) in 1982 and 1983. The survey population was Mexican-Americans residing in five Southwestern states. This report presents data on the prevalence of total tooth loss, dental caries, and periodontal diseases in 3860 Mexican-American adults aged from 18 to 74. Results show that 4.3% of this group was edentulous. Among the dentate, Mexican-Americans had lower overall DMF scores but higher numbers of untreated decayed teeth than did residents of the same region seen in the NHANES I survey in 1971-1974. Caries of the smooth surfaces in both posterior and anterior teeth was more pronounced in the older than in the younger age groups. Mexican-Americans had more gingivitis but fewer periodontal pockets than did the general population in the Western states during NHANES I. The caries pattern in the Mexican-Americans suggests that caries among adults may remain a problem in the future, with the possibility of increased involvement with the aging, although modest, of smooth tooth surfaces. 相似文献
5.
CM Reid M. Nelson P. Beckinsale P. Ryan LMH Wing LJ Beilin MA Brown GLR Jennings CI Johnston J. Marley JJ McNeil TO Morgan J. Shaw ID Steven MJ West 《Clinical and experimental pharmacology & physiology》1997,24(5):370-373
1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial. 相似文献
6.
7.
8.
9.
10.