全文获取类型
收费全文 | 12044篇 |
免费 | 1342篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 110篇 |
儿科学 | 390篇 |
妇产科学 | 317篇 |
基础医学 | 1733篇 |
口腔科学 | 292篇 |
临床医学 | 1439篇 |
内科学 | 2121篇 |
皮肤病学 | 141篇 |
神经病学 | 1199篇 |
特种医学 | 535篇 |
外国民族医学 | 1篇 |
外科学 | 1785篇 |
综合类 | 218篇 |
一般理论 | 6篇 |
预防医学 | 1241篇 |
眼科学 | 191篇 |
药学 | 783篇 |
中国医学 | 20篇 |
肿瘤学 | 891篇 |
出版年
2022年 | 88篇 |
2021年 | 188篇 |
2020年 | 100篇 |
2019年 | 162篇 |
2018年 | 216篇 |
2017年 | 194篇 |
2016年 | 190篇 |
2015年 | 241篇 |
2014年 | 309篇 |
2013年 | 438篇 |
2012年 | 590篇 |
2011年 | 556篇 |
2010年 | 307篇 |
2009年 | 326篇 |
2008年 | 542篇 |
2007年 | 501篇 |
2006年 | 510篇 |
2005年 | 510篇 |
2004年 | 479篇 |
2003年 | 443篇 |
2002年 | 400篇 |
2001年 | 371篇 |
2000年 | 392篇 |
1999年 | 338篇 |
1998年 | 178篇 |
1997年 | 171篇 |
1996年 | 165篇 |
1995年 | 143篇 |
1994年 | 130篇 |
1993年 | 122篇 |
1992年 | 271篇 |
1991年 | 246篇 |
1990年 | 271篇 |
1989年 | 265篇 |
1988年 | 247篇 |
1987年 | 234篇 |
1986年 | 220篇 |
1985年 | 226篇 |
1984年 | 179篇 |
1983年 | 152篇 |
1982年 | 119篇 |
1981年 | 111篇 |
1980年 | 97篇 |
1979年 | 145篇 |
1978年 | 124篇 |
1977年 | 105篇 |
1976年 | 102篇 |
1974年 | 102篇 |
1973年 | 108篇 |
1970年 | 80篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Marjolein C. H. van der Meulen Robert Marcus Laura K. Bachrach Dennis R. Carter 《Journal of orthopaedic research》1997,15(3):473-476
We have developed an analytical model of long bone cross-sectional ontogeny in which appositional growth of the diaphysis is primarily driven by mechanical stimuli associated with increasing body mass during growth and development. In this study, our goal was to compare theoretical predictions of femoral diaphyseal structure from this model with measurements of femoral bone mineral and geometry by dual energy x-ray absorptiometry. Measurements of mid-diaphyseal femoral geometry and structure were made previously in 101 Caucasian adolescents and young adults 9–26 years of age. The data on measured bone mineral content and calculated section modulus were compared with the results of our analytical model of cross-sectional development of the human femur over the same age range. Both bone mineral content and section modulus showed good correspondence with experimental measurements when the relationships with age and body mass were examined. Strong linear relationships were evident for both parameters when examined as a function of body mass. 相似文献
32.
Resting energy expenditure and nutritional state of patients with increased oxygen cost of breathing due to emphysema, scoliosis and thoracoplasty. 总被引:5,自引:3,他引:2 下载免费PDF全文
BACKGROUND--Weight loss is a well recognised feature of patients with emphysematous chronic obstructive pulmonary disease (COPD). It has been suggested that this weight loss could be due to a hypermetabolic state resulting from the increased oxygen cost of breathing (OCB). To clarify the relation between resting energy expenditure (REE), nutritional state, and OCB these indices were measured in patients with respiratory impairment and an increased OCB due to COPD, scoliosis, and thoracoplasty. METHODS--Eighteen patients (six COPD, six scoliosis, six thoracoplasty) of mean (SD) age 59.9 (8.6) years (8M, 10F) and six controls (45.5 (9.9) years; 2M, 4F) were studied. OCB was estimated by the addition of dead space to the breathing circuit and REE was measured by indirect calorimetry using a ventilated canopy system. Height, arm span, weight, triceps skin fold thickness (TSF), mid-arm muscle circumference (MAMC), forced expiratory volume in one second (FEV1), and vital capacity (VC) were measured in all study subjects. RESULTS--OCB was elevated in all patient groups (mean 7.0 ml/l) compared with controls (1.9 ml/l). All patients with COPD, four with scoliosis, three with thoracoplasty, and none of the controls were < 90% ideal body weight. Mean (SD) measured REE as % predicted (Harris-Benedict equation) was 103.8 (7.6) in patients with COPD, 105.5 (10.9) in those with scoliosis, 106.3 (6.9) in the thoracoplasty patients, and 103.3 (3.4) in controls. One patient with COPD, two with scoliosis, two with thoracoplasty, but no controls were hypermetabolic (REE > 110% predicted). In all groups there was a negative relation between OCB and lung function (OCB v FEV1 r = -0.83 in COPD, -0.62 in scoliosis, -0.67 in thoracoplasty, and -0.76 in controls). There was no correlation between REE and OCB or MAMC. CONCLUSIONS--In patients with respiratory disease OCB (augmented ventilation) is related to lung function but not to REE. This is evidence against the hypothesis that hypermetabolism due to increased oxygen cost of breathing at rest is the sole or major cause of malnutrition in patients with lung disease. 相似文献
33.
34.
L F Hiratzka C L Eastham J G Carter J R Moyers D R Elliott D B Doty C B Wright M L Marcus 《The Annals of thoracic surgery》1988,45(5):474-481
In normal coronary arteries, reactive hyperemic responses to a 20-second occlusion, an index of coronary reserve, usually demonstrate a peak-to-resting flow velocity ratio of 4:1 or more. Most intraoperative studies that have assessed reactive hyperemic responses in bypassed vessels have reported peak-to-resting flow velocity ratios of 2:1 or less following a 20-second occlusion. These decreased reactive hyperemic responses could be due to coronary vasodilatation after cardiopulmonary bypass or to an inadequate physiological result of the surgical procedure. In 14 patients with angiographically normal coronary arteries, the peak-to-resting flow velocity ratio following a 20-second coronary occlusion decreased significantly (p less than 0.05) from 4.4 +/- 0.2 (mean +/- standard error) before bypass to 3.0 +/- 0.3 after bypass. In a similar dog model, the peak-to-resting flow velocity ratio decreased by 36 to 52% during the first hour following one hour of cardiopulmonary bypass and cardioplegia. During the same period, left ventricular perfusion increased 21 to 30%, mean arterial pressure and coronary vascular resistance decreased, and myocardial oxygen consumption was unchanged. In a second group of dogs studied for the effects of duration (200 to 240 minutes) of anesthesia and thoracotomy alone, peak-to-resting flow velocity ratio was significantly lower. These clinical and experimental studies suggest that major coronary vasodilatation occurs early following cardiopulmonary bypass and cold cardioplegia, and may contribute to the blunted coronary reactive hyperemic responses reported during this time. Consequently, an intraoperative peak-to-resting flow velocity ratio of 3:1 for bypassed coronary arteries may represent an excellent physiological result. 相似文献
35.
36.
Stress analyses of glenoid component designs 总被引:2,自引:0,他引:2
Metal backing of glenoid components for total shoulder replacements and the use of bony ingrowth surfaces on these components have recently been introduced. In this study, finite element analyses were performed to determine the stress fields in the natural glenoid and to calculate the change in bone stresses after implantation of glenoid components of various designs. The effects of metal backing, keel geometry, and superior constraint on bone stresses indicate that stress distributions on the natural glenoid corresponded to bone morphology. Metal-backing the glenoid component may cause slight improvement in stress transfer to cortical bone. Altered fin geometry better stabilized the glenoid component. Superior restraints on the component intending to prevent subluxation increase stresses and may cause earlier loosening than encountered with unconstrained components. 相似文献
37.
38.
Bourn David; Carter Simon A.; Mason Susan; Evans D.Gareth R.; Strachan Tom 《Human molecular genetics》1994,3(5):813-816
The recent identification of the NF2 tumour suppressor genehas enabled large scale screening for pathological mutationsin the gene. We have sought germline mutations In the NF2 geneby SSCP and heteroduplex analysis of cDNA and genomic DNA samplesfollowed by cloning and sequencing of mutant alleles. In thepresent report we describe 11 putative pathological mutations,including five nonsense mutations, three short insertions ordeletions cauing frameshifts and three missense mutations. Moststop mutations and frameshift mutations were found In Individualsexpressing a severe phenotype while one of the three missensemutations was associated with a mild phenotype. Four unrelatedNF2 patients of the 93 tested were found to have identical nonsensemutations caused by a C to T transition (C169) in a CpG dinucleotide,which is a potential mutational hotspot in the NF2 tumour suppressorgene. 相似文献
39.
40.
W F Tatu W S Holmes W C Black R Mainwaring T Carter 《The Journal of computed tomography》1988,12(1):32-35
We report the imaging findings of an abdominal aggressive angiomyxoma, which communicated with the gastrointestinal tract. The literature on this rare tumor is reviewed. 相似文献