首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1420篇
  免费   122篇
  国内免费   5篇
耳鼻咽喉   7篇
儿科学   30篇
妇产科学   46篇
基础医学   259篇
口腔科学   65篇
临床医学   140篇
内科学   243篇
皮肤病学   49篇
神经病学   207篇
特种医学   46篇
外科学   121篇
综合类   11篇
预防医学   117篇
眼科学   12篇
药学   71篇
中国医学   5篇
肿瘤学   118篇
  2024年   3篇
  2023年   21篇
  2022年   34篇
  2021年   50篇
  2020年   29篇
  2019年   55篇
  2018年   56篇
  2017年   33篇
  2016年   50篇
  2015年   41篇
  2014年   56篇
  2013年   85篇
  2012年   117篇
  2011年   121篇
  2010年   85篇
  2009年   46篇
  2008年   103篇
  2007年   79篇
  2006年   65篇
  2005年   76篇
  2004年   54篇
  2003年   43篇
  2002年   34篇
  2001年   17篇
  2000年   10篇
  1999年   13篇
  1998年   12篇
  1997年   15篇
  1996年   8篇
  1995年   13篇
  1994年   6篇
  1993年   7篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1989年   3篇
  1988年   8篇
  1987年   5篇
  1986年   10篇
  1985年   7篇
  1984年   3篇
  1983年   4篇
  1982年   10篇
  1981年   11篇
  1980年   4篇
  1979年   8篇
  1978年   3篇
  1977年   5篇
  1976年   3篇
  1973年   4篇
排序方式: 共有1547条查询结果,搜索用时 46 毫秒
1.
Caring for patients with end-stage kidney disease (ESKD) in the United States is challenging, due in part to the complex epidemiology of the disease's progression as well as the ways in which care is delivered. As CKD progresses toward ESKD, the number of comorbidities increases and care involves multiple healthcare providers from multiple subspecialties. This occurs in the context of a fragmented US healthcare delivery system that is traditionally siloed by provider specialty, organization, as well as systems of payment and administration. This article describes the role of care fragmentation in the delivery of optimal ESKD care and identifies research gaps in the evidence across the continuum of care. We then consider the impact of care fragmentation on ESKD care from the patient and health system perspectives and explore opportunities for system-level interventions aimed at improving care for patients with ESKD.  相似文献   
2.
PURPOSE: In children with locally advanced or recurrent malignant tumours, prognosis can be improved by regional deep hyperthermia (RHT) in combination with platin-based chemotherapy. However, because of the increasing number of patients that achieve long-time remission with this therapy, it is necessary to evaluate long-term sequelae of thermochemotherapy. During the years 1993-2004 one has observed avascular osteonecrosis (AON) of the femoral head after RHT in seven children with pelvic germ cell tumours or rhabdomyosarcomas. METHODS: Although AON may develop in patients with malignancies treated with chemo- or radiotherapy alone, RHT might nevertheless contribute to the occurrence of AON. In order to determine potential risk factors for AON after RHT, this study analysed the relationship of AON to the patient's age, medical history and treatment parameters such as thermal dose equivalent and power output. RESULTS AND CONCLUSIONS: In the present study AON was associated with young age as well as intensity of hyperthermia indicated by high power levels that exceed 20 W per kg body weight and/or application of eight or more heat sessions as well as additional radiotherapy. Based on this observation, it was assumed that an optimized three dimensional thermal field modelling may be helpful to avoid hazardous temperatures in the femoral heads during RHT treatment and to reduce AON of the femoral heads.  相似文献   
3.
Summary The rotation and structural changes of the apex vertebra in the horizontal plane as well as of the thoracic cage deformity were quantified by measurements on computed tomography (CT) scans from patients with right convex thoracic idiopathic scoliosis (IS). The CT scans were obtained from 12 patients with moderate scoliosis (mean Cobb angle 25.8°, r 13°–30°) and from 33 with severe scoliosis (mean Cobb angle 46.2°, r 35°–71°). In addition, CT scans of thoracic vertebrae from 15 patients without scoliosis were used as reference material. Ten of the scoliotic cases had had Cotrel-Dubousset instrumentation (CDI) and posterior fusion and had entered a longitudinal study on the effect of operative correction on the re-modelling of the apical vertebra. An increasingly asymmetrical vertebral body, transverse process angle, pedicle width and canal width were found in the groups with scoliosis as compared with the reference material. Vertebral rotation and rib hump index were significantly larger in patients with early and advanced scoliosis than in normal subjects. The modelling angle of the vertebral body, the transverse process angle index and the vertebral rotation in relation to the middle axis of the thoracic cage were significantly greater in patients with severe than with moderate scoliosis. The results of this longitudinal study suggest that the structural changes of the apical vertebra regress 2 years or more after CD instrumentation.  相似文献   
4.
In 1906 Bergonié and Tribondeau postulated a correlation between proliferation rate and radiosensitivity. Allowing for modern radiotherapeutic and radiobiological experience this postulate is no longer tenable.  相似文献   
5.
The concave and convex rib-vertebral angle (RVA) at levels T2–T12 was measured on AP radiographs of 19 patients with right convex idiopathic thoracic scoliosis and 10 patients with major thoracic right convex neuromuscular scoliosis. The difference between the angles on the concave and the convex sides, the RVAD, was calculated. The RVAs were also measured on radiographs from three animal groups in which spinal curves had been induced experimentally in a variety of ways. Group 1 comprised 16 rabbits that had been subjected to selective electrostimulation of the latissimus dorsi, the erector spinae and the intercostal muscles. Group 2 comprised four dead rabbits whose spines had been subjected to manual bending. Group 3 comprised eight rabbits that had undergone mechanical elongation of one rib. In both the idiopathic and the neuromuscular group, the convex RVA was smaller than the concave RVA between levels T2 and T8, with a maximal difference between T4 to T5. From T9 to T12 the concave RVA was smaller than the convex. The RVA in relation to the scoliotic segment, i.e. the apex level of the curve and the two neighbouring vertebrae above and below this level, showed similar results. With increasing Cobb angle the RVADs increased linearly with the greatest difference at the second vertebra above the apex. In the three experimental groups the pattern of the RVADs between T6 to T12 was basically similar to the findings of the clinical study. From the results of these clinical and experimental studies, it is concluded that the typical pattern of the RVAs on the concave and convex sides seems to be independent of the underlying cause of the spinal curvature. It is likely that the RVADs result from a passive mechanical adaptation of the ribs to the lateral curvature of the spine.  相似文献   
6.
7.
A single intramuscular injection of 2 mg estradiol valerate (EV) results in neuronal degeneration and β-endorphin depletion in the hypothalamic arcuate nucleus of adult female rats. We have hypothesized that peroxidase-positive astrocytes in this brain region oxidize estrogens and catecholestrogens to semiquinone radicals which mediate oxidative neuronal injury. In the present study, dietary administration of the potent antioxidant 21-aminosteroid, U-74389F, completely blocked EV-induced β-endorphin depletion in the hypothalami of adult female rats. Neither EV nor 21-aminosteroid treatment had any effect on hypothalamic concentrations of neuropeptide Y and Met-enkephalin, confirming that the estradiol lesion is fairly selective for the β-endorphin cell population. The present findings support the hypothesis that the toxic effect of estradiol on hypothalamic β-endorphin neurons is mediated by free radicals.  相似文献   
8.
 Age, hematopoietic growth factors, cyclosporin A, mode of bone marrow transplantation (BMT) (autologous, allogeneic-related, unrelated), and underlying disease were assessed as potential risk factors for capillary leakage syndrome (CLS) in 96 patients after BMT. CLS was defined as unexplained weight gain of >3% within 24 h and nonresponsiveness to furosemide. CLS occurred in 9/21 patients after unrelated compared with 2/33 after allogeneic-related BMT (p=0.0017) for hematopoietic disorders (n=54) and in 6/7 patients after allogeneic-related compared with 3/35 after autologous BMT (p=0.0001) for solid tumors (n=42). Hematopoietic growth factors and cyclosporin A were no signficant risk factors on their own. We conclude that unrelated BMTs or high-intensity conditioning regimens used in combination with allogeneic-related BMT are the main risk factors for CLS. Received: 6 January 1997 / Accepted: 10 March 1997  相似文献   
9.
L A Hilgers  H Snippe  M Jansze    J M Willers 《Immunology》1987,60(1):141-146
Referring to the strong immunostimulating activity of combinations of lipophilic agents and dextran sulphate, conjugates with chemical determinants of both types of adjuvants were synthesized and then examined for immunostimulatory capabilities in mice. Saturated fatty acids with varying chain lengths and sulphate groups were coupled covalently at defined ratios to the polysaccharide Ficoll (MW 400,000). Chemical analysis of 60 of the sulpholipopolysaccharides synthesized revealed that the number of sulphate groups per monosaccharide unit varied from 0 to 1.6, and the number of lipid groups from 0 to 0.8. Adjuvanticity of these conjugates for the humoral immune response was determined using sheep red blood cells (SRBC) and dinitrophenyl-haptenated bovine serum albumin (DNP-BSA) as antigens. Five days after intraperitoneal injection of adjuvant and antigen, the numbers of direct anti-SRBC plaque-forming cells (PFC) in the spleen were determined. Anti-DNP antibody titres were measured from 1 to 4 weeks after immunization. PFC responses to 2 X 10(6) SRBC were augmented up to a 100-fold by conjugates of Ficoll and sulphate (sulphopolysaccharides: SPs) or lipid groups (lipopolysaccharides: LPs). Introduction of low or moderate numbers of lipid groups in SPs reduced adjuvanticity. Adjuvant activity of sulpholipopolysaccharides (SLPs) with varying sulphate and high lipid content depended on the sulphate contents and the chain length of the lipids. Sulphate reduced adjuvanticity of the SLPs, and the number of sulphate groups required for complete annihilation increased with the chain length of the lipid. LPs and SLPs, including conjugates that did not enhance anti-SRBC PFC responses, augmented serum antibody responses to DNP-BSA while SPs were hardly effective.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号