全文获取类型
收费全文 | 4278篇 |
免费 | 338篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 103篇 |
妇产科学 | 123篇 |
基础医学 | 509篇 |
口腔科学 | 67篇 |
临床医学 | 578篇 |
内科学 | 824篇 |
皮肤病学 | 40篇 |
神经病学 | 241篇 |
特种医学 | 292篇 |
外国民族医学 | 1篇 |
外科学 | 667篇 |
综合类 | 127篇 |
一般理论 | 1篇 |
预防医学 | 332篇 |
眼科学 | 55篇 |
药学 | 253篇 |
1篇 | |
中国医学 | 7篇 |
肿瘤学 | 385篇 |
出版年
2023年 | 26篇 |
2022年 | 53篇 |
2021年 | 79篇 |
2020年 | 53篇 |
2019年 | 59篇 |
2018年 | 116篇 |
2017年 | 85篇 |
2016年 | 86篇 |
2015年 | 109篇 |
2014年 | 157篇 |
2013年 | 174篇 |
2012年 | 251篇 |
2011年 | 303篇 |
2010年 | 170篇 |
2009年 | 153篇 |
2008年 | 211篇 |
2007年 | 227篇 |
2006年 | 201篇 |
2005年 | 188篇 |
2004年 | 186篇 |
2003年 | 194篇 |
2002年 | 178篇 |
2001年 | 121篇 |
2000年 | 91篇 |
1999年 | 90篇 |
1998年 | 60篇 |
1997年 | 47篇 |
1996年 | 67篇 |
1995年 | 60篇 |
1994年 | 56篇 |
1993年 | 40篇 |
1992年 | 56篇 |
1991年 | 64篇 |
1990年 | 55篇 |
1989年 | 54篇 |
1988年 | 58篇 |
1987年 | 45篇 |
1986年 | 55篇 |
1985年 | 46篇 |
1984年 | 37篇 |
1983年 | 23篇 |
1982年 | 16篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1978年 | 18篇 |
1975年 | 16篇 |
1972年 | 14篇 |
1971年 | 17篇 |
1969年 | 14篇 |
1966年 | 16篇 |
排序方式: 共有4630条查询结果,搜索用时 15 毫秒
1.
2.
Maher Saqqur MD Michael D. Hill MD MSc FRCPC Andrei V. Alexandrov MD Jayanta Roy MD Marcia Schebel BSc Andrea Krol BSc Zsolt Garami MD Ashfaq Shuaib MD FRCPC Andrew M. Demchuk MD FRCPC 《Journal of neuroimaging》2006,16(4):323-328
BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies. 相似文献
3.
4.
A Decade of Change in Obesity Surgery 总被引:4,自引:0,他引:4
Edward E Mason MD PhD Shenghui Tang MS Kathleen E Renquist BS Dwight T Barnes Joseph J Cullen MD Cornelius Doherty MD James W Maher MD 《Obesity surgery》1997,7(3):189-197
Background: The International (formerly National) Bariatric Surgery Registry began collecting data in January 1986. The aim
of this study was to examine changes in the practice of surgical treatment of severe obesity that occurred during the decade
of 1986 through 1995, as observed in the IBSR data. Methods: All data submitted to the IBSR during the decade were transferred
to the IBM mainframe computer for analysis. Characteristics of operative type populations were compared over time using analysis
of variance (ANOVA) for age, body mass index (BMI), operative weight and Chi-square (χ2) test for gender. Results: There has been a steady increase over the decade in mean patient weight. The operations used have
changed from predominantly ‘simple’ operations to more frequent use of ‘complex’ operations. Within the categories of ‘simple’
and ‘complex’, an increase in the variety of operations occurred. As a group, patients with ‘simple’ operations have been
heavier, more often male and public pay patients than those who have undergone ‘complex’ operations. One year weight loss
was greater for Roux-en-Y gastric bypass (RGB) than vertical banded gastroplasty (VBG), but follow-up rates were too low to
study the relative merits of the operations used. The reported incidence of operative mortality and serious complications
(leak with peritonitis, abscess and pulmonary embolism) remained low. Conclusions: These observations and their implications
can be summarized in three statements which relate to action for improved patient care in the beginning of the new century:
(1) increasing weight of candidates for surgical treatment during this decade indicates the need for earlier use of operative
treatment before irreversible complications of obesity can develop; (2) low risk of obesity surgery, decreasing postoperative
hospital stay, and early weight control support the continued and increased use of surgical treatment; (3) continued widespread
use of both ‘simple’ and ‘complex’ operations with increased modifications of standard RGB and VBG procedures emphasizes the
need for standardized long-term data and analyses regarding both weight control and postoperative side-effects. 相似文献
5.
6.
Do-not-resuscitate orders for critically ill patients in the hospital. How are they used and what is their impact? 总被引:9,自引:0,他引:9
We studied compliance with do-not-resuscitate (DNR) orders at a university hospital where a DNR protocol has existed since 1979. Documentation of DNR status in patient progress notes and chart orders increased through 1983. During a 12-month period (March 1983 through April 1984), we studied in detail the medical records of 521 patients who had a cardiopulmonary arrest in the hospital. Seventy-five percent (389 of 521) of these patients were designated DNR. Patients who were designated DNR were significantly more likely to be older, to have malignancy or an abnormal mental status, and to be less likely to have acute myocardial infarction, stroke, or chronic obstructive pulmonary disease than patients in whom resuscitation was attempted. Eighty-six percent of families, but only 22% of patients, were involved in the decision to designate a patient DNR. The decision to designate a patient DNR occurred late in the course of a patient's illness, often when the patient was in coma. For 28% of patients, some form of medical care was withdrawn or withheld after they were designated DNR. These data suggest that use of the DNR protocol requires changes if patients are to participate in the decision not to undergo cardiopulmonary resuscitation. 相似文献
7.
Ulrich Weber Christian WA Pfirrmann Rudolf O Kissling Juerg Hodler Marco Zanetti 《BMC musculoskeletal disorders》2007,8(1):20
Background
Ankylosing spondylitis is a chronic inflammatory rheumatic disorder which usually begins in early adulthood. The diagnosis is often delayed by many years. MR imaging has become the preferred imaging method for detection of early inflammation of the axial skeleton in ankylosing spondylitis. 相似文献8.
Elise Maher 《Child: care, health and development》2004,30(4):395-396
Early childhood factors influencing health-related quality of life in adolescents at 13 years . Wilkins , A.J. , O'Callaghan , M.J. , Najman , J.M. , Williams , G.M. & Shuttlewood , G. ( 2004 ) Journal of Paediatrics and Child Health 40 , 102 – 109 . 相似文献
9.
Serum ferritin in haemodialysis patients: is there a relationship to 'haemochromatosis alleles' HLA A3, B7, B14? 总被引:1,自引:0,他引:1
Serum ferritin levels were measured in 57 patients on maintenance haemodialysis to determine if patients who possessed 1 or more of the histocompatibility antigens associated with idiopathic haemochromatosis (HLA A3, B7 or B14) were at increased risk of iron overload. There was no significant difference in the mean serum ferritin levels between those patients with HLA A3, B7 or B14 (357.9 +/- 522.6 ng/1; n = 19) and those without these antigens (393.7 + 556.2 ng/1; n = 38). Iron overload in haemodialysis patients is not a histocompatibility-linked disorder. 相似文献
10.