全文获取类型
收费全文 | 4716篇 |
免费 | 452篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 134篇 |
儿科学 | 131篇 |
妇产科学 | 140篇 |
基础医学 | 674篇 |
口腔科学 | 85篇 |
临床医学 | 566篇 |
内科学 | 811篇 |
皮肤病学 | 51篇 |
神经病学 | 325篇 |
特种医学 | 365篇 |
外科学 | 647篇 |
综合类 | 124篇 |
一般理论 | 2篇 |
预防医学 | 442篇 |
眼科学 | 116篇 |
药学 | 355篇 |
1篇 | |
中国医学 | 3篇 |
肿瘤学 | 228篇 |
出版年
2023年 | 47篇 |
2022年 | 36篇 |
2021年 | 74篇 |
2020年 | 70篇 |
2019年 | 89篇 |
2018年 | 115篇 |
2017年 | 81篇 |
2016年 | 93篇 |
2015年 | 99篇 |
2014年 | 120篇 |
2013年 | 191篇 |
2012年 | 252篇 |
2011年 | 263篇 |
2010年 | 137篇 |
2009年 | 133篇 |
2008年 | 212篇 |
2007年 | 206篇 |
2006年 | 203篇 |
2005年 | 224篇 |
2004年 | 209篇 |
2003年 | 175篇 |
2002年 | 188篇 |
2001年 | 102篇 |
2000年 | 119篇 |
1999年 | 90篇 |
1998年 | 66篇 |
1997年 | 54篇 |
1996年 | 63篇 |
1995年 | 65篇 |
1994年 | 58篇 |
1993年 | 57篇 |
1992年 | 118篇 |
1991年 | 91篇 |
1990年 | 77篇 |
1989年 | 84篇 |
1988年 | 75篇 |
1987年 | 78篇 |
1986年 | 66篇 |
1985年 | 67篇 |
1984年 | 57篇 |
1983年 | 54篇 |
1982年 | 25篇 |
1981年 | 26篇 |
1980年 | 29篇 |
1979年 | 26篇 |
1978年 | 35篇 |
1977年 | 27篇 |
1976年 | 30篇 |
1974年 | 39篇 |
1973年 | 34篇 |
排序方式: 共有5200条查询结果,搜索用时 11 毫秒
61.
An Unexpected Change in DXA Calibration not Detected by Routine Quality Control Checks 总被引:2,自引:0,他引:2
G. M. Blake N. G. Preston R. Patel R. J. M. Herd I. Fogelman 《Osteoporosis international》1999,9(2):115-120
Since its commercial introduction a decade ago, the technique of dual-energy X-ray absorptiometry (DXA) has been widely recognized
as a useful and sensitive method of measuring changes in bone mineral density (BMD) at selected sites in the skeleton such
as the spine and proximal femur. Because of their high precision and stable calibration, DXA scanners are frequently used
in clinical trials to evaluate new treatments for osteoporosis. Quality assurance procedures based on regular scanning of
phantoms are widely adopted in such trials, and continuity of the phantom BMD measurements is generally believed to ensure
continuity in the in-vivo calibration. We report a change in calibration of a DXA scanner that occurred during a clinical
trial where the calibration shift was different for the spine and femur sites and was not predicted or explained by the standard
quality control procedures using phantoms. However, we show that provided patients enrolled in studies are thoroughly randomized
and the statistical analysis is confined to the differences between the treated and control groups, then the effects of such
calibration shifts on conclusions regarding the efficacy of treatment are considerably smaller than the random statistical
errors.
Received: 12 February 1998 / Accepted: 20 May 1998 相似文献
62.
Simmonds NJ Millar AD Blake DR Rampton DS 《Alimentary pharmacology & therapeutics》1999,13(3):363-372
BACKGROUND: The therapeutic efficacy of 5-aminosalicylic acid in inflammatory bowel disease may be related to its antioxidant properties. AIM: To compare in vitro the antioxidant effects of conventional drugs (5-aminosalicylic acid, corticosteroids, metronidazole), with new aminosalicylates (4-aminosalicylic acid, balsalazide) and other potential therapies (ascorbate, N-acetylcysteine, glutathione, verapamil). METHODS: Compounds were assessed for efficacy in reducing the in vitro production of reactive oxygen species by cell-free systems (using xanthine/xanthine oxidase, with or without myeloperoxidase) and by colorectal biopsies from patients with ulcerative colitis using luminol-amplified chemiluminescence. RESULTS: 5-aminosalicylic acid and balsalazide were more potent antioxidants than 4-aminosalicylic acid or N-acetyl-5-aminosalicylic acid in cell-free systems. 5-aminosalicylic acid (20 mM) and balsalazide (20 mM) inhibited rectal biopsy chemiluminescence by 93% and 100%, respectively, compared with only 59% inhibition by 4-aminosalicylic acid (20 mM). Hydrocortisone, metronidazole and verapamil had no significant effect on chemiluminescence in any system. Ascorbate (20 mM) inhibited chemiluminescence by 100% in cell-free systems and by 60% in rectal biopsies. N-acetyl cysteine (10 mM), and both oxidized and reduced glutathione (10 mM), completely inhibited chemiluminescence in cell-free systems, but not with rectal biopsies. CONCLUSIONS: The antioxidant effects of compounds varies between cell-free systems and inflamed colorectal biopsies. The effect of drugs on the chemiluminescence produced by these two assay systems is useful for screening potentially new antioxidant treatments for inflammatory bowel disease. Ascorbate seems worth further study as a novel therapy. 相似文献
63.
Blake SM Caspersen CJ Finnegan J Crow RA Mittlemark MB Ringhofer KR 《American journal of health promotion : AJHP》1996,11(1):23-34
PURPOSE: To assess organizational and employee participation during three community-wide worksite exercise competitions in two communities. DESIGN: A one-group, posttest-only design was used. Lack of controls, exercise baseline, and the short-term nature of the interventions were limitations. SETTING: The Minnesota Heart Health Program conducted annual exercise campaigns between 1982 and 1989 within three intervention communities to reduce behavioral risk for cardiovascular disease. The Shape Up Challenge was a worksite exercise competition designed, in conjunction with other campaign activities, to increase levels of physical activity. SUBJECTS: A total of 119 participating companies in two Minnesota communities, and 17,626 employees within these worksites, composed the subjects in this study. INTERVENTION: Eligible worksites were invited to participate in a month-long competition during which employees recorded minutes spent daily in aerobic activities. Incentives were established to promote intragroup cooperation and intergroup competition. Companies competed for awards that were based on average minutes of exercise per employee versus per participant. MEASURES: Numbers of companies recruited and participating, campaign activities, minutes of exercise, and costs were recorded on implementation logs. Companies completed surveys describing business type, number and sex of employees, existing health promotion programs, and perceived benefits of participation. RESULTS: Of the 365 companies invited to participate, 33% participated (range 15% to 50%). Participating companies were more likely than nonparticipating companies to offer other health promotion programs and perceived greater benefits from participation. Women and smaller companies had significantly greater participation rates than men and larger companies. Average employee participation rates ranged from as high as 84% in smaller organizations to as low as 16% as organization size increased. CONCLUSIONS: Community-based worksite exercise competitions appear to be a viable strategy for promoting employee exercise, particularly in smaller companies. Group-based contingencies applied in natural work units may facilitate employee participation. Further research is needed to assess the relative efficacy of this approach, compare alternative incentives, and identify strategies to enhance exercise maintenance after the intervention has ceased. 相似文献
64.
65.
66.
Paul M. Busse M.D. Ph.D. Blake Cady M.D. Albert Bothe Jr. M.D. Roger Jenkins M.D. William V. McDermott M.D. Glenn Steele Jr. M.D. Ph.D. Michael D. Stone M.D. 《World journal of surgery》1991,15(3):352-356
The recognition of a high incidence of local failure following surgical management of adenocarcinoma of the gallbladder has led to the use of adjuvant radiation therapy. In order to deliver higher doses to the gallbladder bed, intraoperative radiation therapy (IORT) has been used both with and without external beam radiation.The experience to date is reviewed. Ten patients have been treated, all of whom had either gross residual or unresected disease. The median survival for the group was approximately 1 year. There were no long-term survivors. The IORT did not contribute to the overall morbidity.Because of the limited number of patients and the advanced nature of the disease, the role of IORT in the management of gallbladder carcinoma has yet to be determined. The utility of this modality will most likely reside in the treatment of minimal residual disease at the time of cholecystectomy rather than in the palliative treatment of unresectable tumors.
Resumen El reconocimiento de la elevada tasa de falla local en el tratamiento del adenocarcinoma de la vesícula biliar, ha motivado el uso de radioterapia adyuvante. Con el objeto de administrar altas dosis de irradiación al lecho de la vesícula billiar, se ha utilizado la radioterapia intraoperatoria (RTIO) con y sin irradiación externa.Se revisa la experiencia hasta la fecha. Diez pacientes han sido tratados, todos con enfermedad macroscópica residual o no resecable. La sobrevida media para el grupo fue de aproximadamente un año; no hay sobrevivientes a largo plazo. La RTIO no contribuyó a la morbilidad global.Debido al limitado número de pacientes y a lo avanzado de la enfermedad, el rol de la RTIO está aun por determinar. La utilidad de esta modalidad muy posiblemente habrá de residir en el tratamiento de enfermedad residual miima en el momento de la colecistectomiá, más qu en el tratamiento paliativo de tumores no resecables.
Résumé Reconnaître la fréquence importante des échecs locaux à la suite du traitement chirurgical de l'adénocarcinome de la vésicule a amené à ajouter la radiothérapie. Pour pouvoir donner des doses plus importantes au lit de la vésicule, l'irradiation peropératoire (IP) a été administrée à la fois avec et sans irradiation externe. L'expérience à ce jour a été passée en revue. Dix patients ont été traités qui avaient soit une grosse tumeur résiduelle soit un cancer non réséqué. La survie moyenne du groupe était d'un an à peu près. Il n'y a eu aucun survivant à long terme. L'IP n'a rien changé à la mortalité globale. Compte tenu du nombre limité des patients et de la nature avancée de la maladie, le rôle de l'IP dans le traitement du cancer de la vésicule reste à déterminer. La valeur de l'IP sera probablement de traiter la petite tumeur résiduelle au moment de la cholécystectomie plutôt que les tumeurs non résécables.相似文献
67.
The inexhaustible beta cell. 总被引:1,自引:0,他引:1
Repeated intensive pancreatic beta-cell stimulation was carried out in 42 subjects, comprising 22 normal controls, 10 mild to "severe" maturity-onset diabetics, and 10 chronic pancreatitis patients. Each subject received 75 gm. oral glucose twice and 1 mg. glucagon plus 0.5 gm. tolbutamide intravenously three times at short intervals. Each of the three combined stimuli caused almost equivalent marked spikes of insulin release in all experimental groups. The total calculated output of insulin was equivalent to the total daily insulin output in normal subjects. Pancreatitics and those with severe diabetes (fasting blood sugar greater than 120 mg./100 ml.) had qualitatively similar but a quantitatively smaller response. Those with mild diabetes were similar to the normal subjects but had an exaggerated response to the second oral glucose dose, suggesting overactivity of the enteroinsular axis. Despite the inordinate insulin levels, hypoglycemia did not occur. 相似文献
68.
69.
A retrospective review was undertaken of the medical records of 52 women with stage II carcinoma of the endometrium who received adjuvant radiotherapy following surgery. The information was obtained from medical notes and a hospital database. Actuarial disease-free survival was 68% at 5 years for those women with stage IIA disease, and 70% at 5 years for those women with stage IIB disease. 6 of the women (11.5%) had side effects from treatment. In contrast to the literature, the only statistically significant prognostic factor in this study was histological differentiation; patients with poorly differentiated tumours fared worse (p = 0.05). This may indicate that a greater number than 52 women is needed to demonstrate weaker prognostic factors such as substage. A larger review is being undertaken of the remaining women recorded on the database, with stage I, III and IV disease. 相似文献
70.
The objective of this study was to evaluate whether the pharmacological activity of cyclical etidronate therapy is sustained
beyond the dosing period. A group of 121 postmenopausal women who had completed a 2-year, double-blind, placebo-controlled
parallel study with etidronate or placebo (400 mg/day for 14 days every 3 months) and calcium agreed to participate in a 1-year
open-label follow-up study to evaluate the effect of discontinuing etidronate treatment. Fifty-nine subjects in the former
etidronate group and 62 in the placebo group received 500 mg/day of elemental calcium; 54/59 and 58/62 subjects, respectively,
completed the study. Outcomes of the study were bone mineral density (BMD), measured by dual energy X-ray absorptiometry (DXA),
and biochemical markers of bone turnover (urinary deoxypyridinoline/creatinine and serum osteocalcin). To determine whether
there was a residual effect of previous therapy we compared mean percentage changes from baseline (year 0) to year 3 for both
spinal and femoral neck BMD and markers of bone turnover in the former cyclical etidronate and placebo groups. To evaluate
the carryover effect of treatment we compared the percent change from year 2 to year 3 for the same variables. Mean percentage
change (SEM) from year 2 to year 3 for spinal BMD in the former cyclical etidronate group was −2.87% (0.48%) versus −0.99%
(0.36%) in the placebo group (P= 0.0022). In the femoral neck, the BMD changes were −0.86% (0.42%) versus −1.01% (0.41%) (NS). Biochemical markers increased
within 6 months toward baseline levels. Mean percentage changes from baseline (year 0) in both spinal and femoral neck BMD
were significantly different between groups 1 year after treatment discontinuation. No differences between groups were maintained
in deoxypyridinoline and osteocalcin. It is concluded that following withdrawal of cyclical etidronate therapy bone loss resumes
at a normal and moderately accelerated rate in the proximal femur and lumbar spine, respectively. A positive effect on BMD
at both cortical and trabecular sites is maintained for 1 year after treatment withdrawal.
Received: 8 May 1999 / Accepted: 10 December 1999 相似文献