全文获取类型
收费全文 | 418846篇 |
免费 | 14340篇 |
国内免费 | 1092篇 |
专业分类
耳鼻咽喉 | 6192篇 |
儿科学 | 13907篇 |
妇产科学 | 11215篇 |
基础医学 | 56933篇 |
口腔科学 | 13153篇 |
临床医学 | 29293篇 |
内科学 | 85555篇 |
皮肤病学 | 10899篇 |
神经病学 | 30682篇 |
特种医学 | 15986篇 |
外国民族医学 | 105篇 |
外科学 | 55203篇 |
综合类 | 2354篇 |
一般理论 | 51篇 |
预防医学 | 41553篇 |
眼科学 | 9711篇 |
药学 | 30742篇 |
2篇 | |
中国医学 | 1255篇 |
肿瘤学 | 19487篇 |
出版年
2022年 | 2370篇 |
2021年 | 5535篇 |
2020年 | 2962篇 |
2019年 | 5147篇 |
2018年 | 10650篇 |
2017年 | 8182篇 |
2016年 | 7427篇 |
2015年 | 9160篇 |
2014年 | 10248篇 |
2013年 | 12484篇 |
2012年 | 23613篇 |
2011年 | 19974篇 |
2010年 | 10295篇 |
2009年 | 10044篇 |
2008年 | 14360篇 |
2007年 | 15612篇 |
2006年 | 15236篇 |
2005年 | 22841篇 |
2004年 | 23448篇 |
2003年 | 18427篇 |
2002年 | 13211篇 |
2001年 | 10695篇 |
2000年 | 8952篇 |
1999年 | 11143篇 |
1998年 | 1947篇 |
1992年 | 9361篇 |
1991年 | 9231篇 |
1990年 | 9468篇 |
1989年 | 8750篇 |
1988年 | 8237篇 |
1987年 | 7823篇 |
1986年 | 7569篇 |
1985年 | 6743篇 |
1984年 | 4692篇 |
1983年 | 3869篇 |
1979年 | 5046篇 |
1978年 | 3218篇 |
1977年 | 2606篇 |
1976年 | 2342篇 |
1975年 | 3378篇 |
1974年 | 4258篇 |
1973年 | 3924篇 |
1972年 | 3870篇 |
1971年 | 3829篇 |
1970年 | 3574篇 |
1969年 | 3513篇 |
1968年 | 3343篇 |
1967年 | 3148篇 |
1966年 | 2744篇 |
1965年 | 1674篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
j. gonenne t. esfandyari m. camilleri d. d. burton d. a. stephens k. l. baxter a. r. zinsmeister † & a. e. bharucha 《Neurogastroenterology and motility》2006,18(10):911-918
Females are disproportionately affected by constipation, which is often aggravated during pregnancy. Bowel function also changes during the luteal phase of the menstrual cycle. The aim was to compare the effects of acute administration of female sex steroids on gastric emptying, small bowel transit and colonic transit in healthy postmenopausal subjects. A second aim was to determine whether withdrawal of the hormones was associated with a change in transit. Forty-nine postmenopausal females were randomized to receive for 7 days 400 mg day(-1) micronized progesterone, 0.2 mg day(-1) oestradiol, combination of the two, or placebo. Treatment groups were balanced on age. Participants underwent whole gut transit measurement by scintigraphy using a 99m-labeled technetium-egg meal and 111-labeled indium-charcoal via a delayed-release capsule. Transit measurement was repeated after withdrawal of the study medications. The primary endpoints were ascending colon (AC) emptying half-life time (t1/2) and colonic geometric centre (GC) at 24 h. Secondary analysis variables were GC at 4 and 48 h, gastric emptying t1/2 and colonic filling at 6 h. There was a significant overall effect of progesterone on colonic transit with shorter AC emptying t1/2 and significantly greater colonic GC at 48 h. No transit endpoints were altered by oestradiol or combined hormonal treatment relative to placebo. Oestradiol and progesterone resulted in looser stool consistency. Withdrawal of the hormone supplement was not associated with significant alteration in transit. Micronized progesterone does not retard colonic transit in postmenopausal females. 相似文献
992.
M A Ye?ilipek G Lüleci N Oygür S Berker O Yegin 《The Turkish journal of pediatrics》1992,34(4):251-254
Cytogenetic abnormalities are rarely found in patients with juvenile chronic myelogenous leukemia (JCML). In patients with chromosomal abnormalities, chromosomes 7 and 8 are usually involved. A case of JCML with 47 XXX and a 46 XX karyotype is described and the literature is reviewed. To our knowledge, this is the first case ever to have been reported. 相似文献
993.
Histological studies describe in detail the changes of the small arteries wall with controversial results concerning lumen narrowing during the aging process. In this study, the anatomic and the angiographic parameters of the medial and lateral lenticulostriate arteries were analysed in 64 carotid angiograms. Only 20% of the total number of lenticulostriate arteries were shown on angiograms. Collateral branches were rarely visible, especially those of medial group. The course of the lenticulostriate arteries was mostly straight or moderately tortuous. No significant differences were noted in any of the measured parameters when compared with the age (p greater than 0.05). It appears that age-related changes spread over external layers of small arteries, with no lumen narrowing or filling defect. 相似文献
994.
J Strausz S Kis J Juhász A Bede J Elek Z Monostori G Nagy I Repa 《Orvosi hetilap》1992,133(36):2293-2296
Six patients with obstruction of the trachea were treated with silicone rubber endothracheal stents implanted with flexible bronchoscope. In every case the stent caused significant clinical improvement of the ventilation. At the postintubation stenosis the stent can result a final recovery, at the malignant processes the implantation seems to be a new palliative method. 相似文献
995.
996.
An 19 year old male patient with cystic fibrosis is reported. The clinical, pathogenetic, anatomical features and literature data are reviewed. Attention is called to recent diagnostic facilities. 相似文献
997.
The complete amino acid sequences of chicken and turkey beta 2-microglobulins have been determined by analyses of tryptic, V8-proteolytic and cyanogen bromide fragments, and by N-terminal sequencing. Mass spectrometric analysis of chicken beta 2-microglobulin supports the sequence-derived Mr of 11,048. The higher apparent Mr obtained for the avian beta 2-microglobulins as compared to human beta 2-microglobulin by SDS-PAGE is not understood. Chicken and turkey beta 2-microglobulin consist of 98 residues and deviate at seven positions: 60, 66, 74-76, 78 and 82. The chicken and turkey sequences are identical to human beta 2-microglobulin at 46 and 47 positions, respectively, and to bovine beta 2-microglobulin at 47 positions, i.e. there is about 47% identity between avian and mammalian beta 2-microglobulins. The known X-ray crystallographic structures of bovine beta 2-microglobulin and human HLA-A2 complex suggest that the seven chicken to turkey differences are exposed to solvent in the avian MHC class I complex. The key residues of beta 2-microglobulin involved in alpha chain contacts within the MHC class I molecule are highly conserved between chicken and man. This explains that heterologous human beta 2-microglobulin can substitute the chicken beta 2-microglobulin in exchange studies with B-F (chicken MHC class I molecule), and suggests that the MHC class I structure is conserved over long evolutionary distances. 相似文献
998.
J M G?tz A J Nielander P J Brouwers C H ten Napel 《Nederlands tijdschrift voor geneeskunde》1992,136(33):1611-1613
Transfusion-associated symptomatic HIV infection in four patients led to death in two patients and to development of serious neurological sequelae in a third patient who also transmitted HIV infection to his spouse. The tardy diagnosis of HIV-associated disease in all cases can be ascribed to ignoring the earlier blood transfusion as a possible cause of HIV infection. This was due partly to advanced age of the patients and partly to lack of familiarity of the attending physicians with HIV-associated problems. This resulted in a substantial doctor's delay. 相似文献
999.
Sergio Navarro-Gutiérrez Félix González-Martínez Maria Teresa Fernández-Pérez Maria Teresa García-Moreno Maria Rosa Ballester-Vidal Francisco J Pulido-Morillo 《European journal of emergency medicine》2003,10(4):331-333
Alterations in blood glucose levels are known to be involved in electrocardiogram changes. Various types of arrhythmias have been reported. We present here the case of an 81-year-old woman presenting with transient atrial fibrillation while being treated for hypoglycaemia with dextrose infusion, and finally developing a sinus rhythm. The presence of alterations in glucose blood levels should always be considered as a potential cause of transient atrial fibrillation. 相似文献
1000.
Renal dysfunction after myocardial revascularization. 总被引:5,自引:0,他引:5
Pedro E Antunes David Prieto J Ferr?o de Oliveira Manuel J Antunes 《European journal of cardio-thoracic surgery》2004,25(4):597-604
OBJECTIVES: In this study, we evaluate the incidence of and analyse the pre and intraoperative risk factors for the development of postoperative renal dysfunction (PRD), and the impact of such an event on perioperative mortality and on hospital length of stay. In addition, we sought to investigate the influence of a mildly increased serum creatinine (1.3-2.0 mg/dl) on perioperative mortality and morbidity. METHODS: The study included 2445 consecutive patients who had no pre-existing renal disease (creatinine or=2.1 mg/dl with a preoperative-to-postoperative increase >or=0.9 mg/dl. Univariate and multivariate analyses were performed where appropriate. RESULTS: Global 30-day mortality was 0.7%. The incidence of PRD was 5.6% (136 patients). Mortality for patients who experienced PRD was 8.8 vs. 0.1% for patients who did not (P<0.001). PRD increased the length of hospital stay by 3.4 days (7.6 vs. 11.0 days; P<0.001), and patients who needed haemodialysis (11%) had a perioperative mortality of 33.3% and a mean hospital length of stay of 16 days. Multivariable logistic regression identified the following variables as independent predictors of PRD: age (P=0.017; odds ratio (OR) 1.3 per 10 years), angina class III/IV (P=0.003; OR 1.7); cardiopulmonary bypass time (P=0.007; OR 1.01 per minute); preoperative serum creatinine levels: group 1 (1.3-1.6 mg/dl (P<0.001; OR 5.5)) and group 2 (1.7-2.0 mg/dl (P<0.001; OR 14.2)). Finally, a mild elevation of the preoperative creatinine level (1.3-2.0 mg/dl) increased significantly the probability of perioperative mortality, low cardiac output, haemodialysis and prolonged hospital stay. CONCLUSIONS: Although the likelihood of PRD in patients without pre-existing renal dysfunction is relatively low, it dramatically increases mortality, morbidity and length of stay after CABG. Mildly elevated (>1.2 mg/dl) preoperative serum creatinine level significantly increases the perioperative mortality and morbidity. 相似文献