全文获取类型
收费全文 | 19027篇 |
免费 | 1998篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 165篇 |
儿科学 | 528篇 |
妇产科学 | 501篇 |
基础医学 | 2592篇 |
口腔科学 | 360篇 |
临床医学 | 2120篇 |
内科学 | 3839篇 |
皮肤病学 | 187篇 |
神经病学 | 2043篇 |
特种医学 | 709篇 |
外科学 | 2788篇 |
综合类 | 363篇 |
一般理论 | 14篇 |
预防医学 | 1846篇 |
眼科学 | 280篇 |
药学 | 1181篇 |
中国医学 | 5篇 |
肿瘤学 | 1530篇 |
出版年
2021年 | 262篇 |
2020年 | 165篇 |
2019年 | 269篇 |
2018年 | 302篇 |
2017年 | 236篇 |
2016年 | 265篇 |
2015年 | 278篇 |
2014年 | 389篇 |
2013年 | 672篇 |
2012年 | 856篇 |
2011年 | 930篇 |
2010年 | 493篇 |
2009年 | 547篇 |
2008年 | 816篇 |
2007年 | 871篇 |
2006年 | 838篇 |
2005年 | 914篇 |
2004年 | 841篇 |
2003年 | 787篇 |
2002年 | 764篇 |
2001年 | 624篇 |
2000年 | 647篇 |
1999年 | 597篇 |
1998年 | 258篇 |
1997年 | 218篇 |
1996年 | 219篇 |
1995年 | 184篇 |
1994年 | 197篇 |
1993年 | 182篇 |
1992年 | 430篇 |
1991年 | 419篇 |
1990年 | 408篇 |
1989年 | 430篇 |
1988年 | 344篇 |
1987年 | 347篇 |
1986年 | 338篇 |
1985年 | 308篇 |
1984年 | 252篇 |
1983年 | 206篇 |
1982年 | 166篇 |
1981年 | 145篇 |
1980年 | 128篇 |
1979年 | 211篇 |
1978年 | 174篇 |
1977年 | 140篇 |
1976年 | 137篇 |
1974年 | 176篇 |
1973年 | 139篇 |
1972年 | 152篇 |
1971年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
In 1987, die Department of Health in the UK set up a working party to identify reasons contributing to a shortfall in donor organs. One recommendation was reimbursement to the District Health Authorities for costs incurred in providing the donor organs. The figure chosen was not to be seen as an incentive to donate organs, merely as an appropriate compensation for the costs incurred. There would be no direct payment to doctors, trustees or relatives of the donor. With the development of the competitive health care environment in the United Kingdom, the reimbursement of donating hospital costs is being considered with these data. 相似文献
22.
23.
24.
S. Gururangan R. A. M. Lawson P. Morris Jones R. F. Stevens R. H. A. Campbell 《Pediatric hematology and oncology》1992,9(2):107-113
The role of open lung biopsy (OLB) in the diagnosis of the etiology of lung infiltrates in children was analyzed for a 10-year period 1979-1989 in a tertiary referral center. A total of 18 children had 19 lung biopsies to ascertain the cause of lung infiltrates. Thirteen of these children (72 %) were immunocompromised due to treatment of hematological/solid malignancies and bone marrow transplantation. The clinical diagnosis was bilateral lung infiltrates of unknown etiology in 17 of 18 children. Eight of these children were ventilated for respiratory failure. The biopsy was useful in achieving a histological diagnosis in 18 of 19 samples (diagnostic yield 95%) and an etiological diagnosis in 14 of 19 samples (etiological yield 74 %). Therapeutic strategy was altered in 14 of 18 patients based on the biopsy results. Five of 14 patients responded favorably to a change in specific treatment. The lime interval from onset of respiratory illness to biopsy was 2-60 days (mean 16 days). Despite the critical state of these children there were few complications associated with the biopsy and no mortality directly related to the procedure. We recommend that OLE be undertaken sooner rather than later in immunocompromised children with bilateral pulmonary infiltrates of unknown etiology. 相似文献
25.
26.
Ketanserin, a recently developed 5-HT2 receptor antagonist, competitively and selectively blocks the vasoconstrictor activity of 5-hydroxytryptamine (serotonin). We explored a possible contribution of serotonin to augmented vascular tone in patients with severe heart failure, using intravenous and oral formulations of ketanserin. When administered intravenously (10 mg bolus, 4 mg/hr infusion for +/- 40 min) to 10 patients with congestive heart failure (NYHA III or IV) secondary to congestive cardiomyopathy (n = 8) or ischemic heart disease (n = 2), the drug produced a significant increase in cardiac output (rest 24%, p less than 0.001; exercise 19%, p less than 0.01) which was accompanied by a fall in systemic arterial pressure (rest 7%, p less than 0.001; exercise 10%, p less than 0.05) and pulmonary wedge (rest 17%, p less than 0.05; exercise 23%, p less than 0.001) pressure. Calculated systemic vascular resistance (SVR, rest 27%, p less than 0.001; exercise 23%, p less than 0.05) decreased significantly. No significant hemodynamic changes were observed when 40 mg of ketanserin was administered orally to the same group of patients. Plasma catecholamines (norepinephrine, NEP:epinephrine, EP:dopamine) were measured before and after ketanserin at rest and during exercise. Baseline NEP levels were markedly elevated at rest and during exercise in all patients (rest: 878 +/- 381 ng/mL, exercise: 1453 +/- 697 ng/mL). Baseline EP levels were within normal limits. Ketanserin did not produce any change in catecholamine concentration.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
27.
Habitat characteristics were examined in two marshes and the littoral zones of two lakes in central Florida to determine their effect on the density and distribution of Coquillettidia perturbans. Larval and water samples were collected and habitat characteristics were recorded at monthly intervals for one year. Several significantly different physicochemical parameters were found between the marshes and lakeshores. Sites with dissolved oxygen less than 1.5 mg/liter (from October through May), pH less than 5.2, total alkalinity less than 6.0 mg CaCO3/liter, and orthophosphate less than 0.25 mg/liter were associated with significantly higher concentrations of Cq. perturbans. Arrow-arum, caric sedge, and maidencane were also associated with higher numbers of Coquillettidia. 相似文献
28.
Effect of meal on the physiological and physicochemical actions of potassium citrate 总被引:1,自引:0,他引:1
The effect of meals on the physiological and physicochemical actions of potassium citrate was examined in 8 patients with nephrolithiasis maintained on a constant metabolic dietary regimen. Potassium citrate (20 mEq. 3 times per day), whether given with food or on an empty stomach, significantly increased urinary pH, citrate and potassium, and decreased urinary calcium and ammonium. Moreover, potassium citrate decreased urinary saturation of calcium oxalate and uric acid, although it slightly increased that of brushite. However, there was no significant difference in these measures when the drug was given with meals from the time when it was given on an empty stomach. Thus, the effect of potassium citrate on urinary risk factors is unaffected by food. 相似文献
29.
Alzheimer's disease can be accurately diagnosed by clinical methods alone in about 90% of cases. The adoption of uniform diagnostic criteria and assessment procedures, such as those developed by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), will likely improve the characterization of the disease across a variety of clinical settings. In general, Alzheimer's disease is a relentlessly progressive disorder; however, it also is clinically heterogeneous. This is underscored by its diverse cognitive deficits, neurologic features, behavioral pathology, and rates of progression. 相似文献
30.
J C Henry T van Amelsvoort R G Morris M J Owen D G M Murphy K C Murphy 《Neuropsychologia》2002,40(5):471-478
Velo-cardio-facial syndrome (VCFS) is associated with deletions on the long arm of chromosome 22, mild intellectual disability, poor social interaction and a high prevalence of psychosis. However, to date there have been no studies investigating the neuropsychological functioning of adults with VCFS. We compared 19 adults with VCFS with 19 age, gender and IQ matched controls using a comprehensive neuropsychological battery. Compared to controls, adults with VCFS had significant impairments in visuoperceptual ability (Visual Object and Space Perception Battery), problem solving and planning (Tower of London) and abstract and social thinking (Comprehension WAIS-R). It is likely that haploinsufficiency (reduced gene dosage) of a neurodevelopmental gene or genes mapping to chromosome 22q11 underlies the cognitive deficits observed in individuals with VCFS. 相似文献