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   4257篇
  免费   294篇
  国内免费   21篇
耳鼻咽喉   27篇
儿科学   172篇
妇产科学   94篇
基础医学   639篇
口腔科学   83篇
临床医学   435篇
内科学   949篇
皮肤病学   85篇
神经病学   351篇
特种医学   189篇
外科学   423篇
综合类   137篇
一般理论   3篇
预防医学   315篇
眼科学   55篇
药学   278篇
中国医学   8篇
肿瘤学   329篇
  2023年   38篇
  2022年   44篇
  2021年   154篇
  2020年   82篇
  2019年   104篇
  2018年   100篇
  2017年   72篇
  2016年   113篇
  2015年   117篇
  2014年   131篇
  2013年   190篇
  2012年   259篇
  2011年   265篇
  2010年   163篇
  2009年   129篇
  2008年   228篇
  2007年   236篇
  2006年   232篇
  2005年   211篇
  2004年   187篇
  2003年   167篇
  2002年   172篇
  2001年   82篇
  2000年   63篇
  1999年   74篇
  1998年   75篇
  1997年   54篇
  1996年   45篇
  1995年   32篇
  1994年   55篇
  1993年   18篇
  1992年   45篇
  1991年   35篇
  1990年   42篇
  1989年   40篇
  1988年   50篇
  1987年   36篇
  1986年   39篇
  1985年   33篇
  1984年   31篇
  1983年   29篇
  1982年   21篇
  1981年   18篇
  1980年   16篇
  1979年   21篇
  1978年   16篇
  1977年   15篇
  1976年   14篇
  1972年   12篇
  1966年   10篇
排序方式: 共有4572条查询结果,搜索用时 15 毫秒
991.
A case of hepatocellular carcinoma with invasion of the portal vein is reported. A tumor defect within the dilated portal vein is well demonstrated by computed tomography, and its appearance is compatible with the "thread and streaks" sign seen on hepatic angiography.  相似文献   
992.
993.
BackgroundPerson‐centred care (PCC) has been suggested as a potential means to improve the care of patients with chronic and long‐term disorders. In this regard, a model for PCC was developed by the University of Gothenburg Centre for Person‐Centred Care (GPCC).ObjectiveThe present study aimed to explore the theoretical frameworks, designs, contexts and intervention characteristics in the first 27 interventional studies conducted based on the ethics for person‐centredness provided by the GPCC.DesignCross‐sectional study.Setting and participantsA questionnaire to the principal investigators of the 27 intervention studies financed by the GPCC and conducted between 2010 and 2016.Main outcome measuresTheoretical frameworks, contexts of studies, person‐centred ethic, and outcome measures.ResultsMost of the interventions were based on the same ethical assumptions for person‐centredness but theories and models in applying the interventions differed. All studies were controlled; 12 randomized and 15 quasi‐experimental. Hospital in‐ and outpatient and primary care settings were represented and the outcome measures were related to the specific theories used. A complexity in designing, introducing and evaluating PCC interventions was evident.ConclusionThe frameworks, designs and interventions in the studies were in line with the established ethical basis of PCC, whereas outcome measures varied widely. Consensus discussions among researchers in the field are needed to make comparisons between studies feasible.Patient or public contributionsPatients or the public made no direct contributions, although most of the studied projects included such initiatives.  相似文献   
994.
To examine whether supplementation with low doses of fish or milk proteins would affect glucose regulation and circulating lipid concentrations in overweight healthy adults. Ninety-three overweight adults were assigned to receive 2.5 g protein/day from herring (HER), salmon (SAL), cod (COD) or milk (CAS, a casein–whey mixture as positive control) as tablets for 8 weeks. Seventy-seven participants were included in the analyses. HER and SAL did not affect glucose and insulin concentrations. COD significantly reduced within-group changes in 90 and 120 min postprandial glucose concentrations but changes were not different from HER and SAL groups. CAS supplementation significantly reduced the area under the curve for glucose concentrations (− 7%), especially when compared to SAL group, and reduced postprandial insulin c-peptide concentration (− 23%). Reductions in acetoacetate (− 24%) and β-hydroxybutyrate (− 29%) serum concentrations in HER group were more prominent compared to SAL and COD groups, with no differences between fish protein groups for α-hydroxybutyrate. Serum concentrations of α-hydroxybutyrate (− 23%), acetoacetate (− 39%) and β-hydroxybutyrate (− 40%) were significantly reduced within CAS group, and the decreases were significantly more pronounced when compared to SAL group. Serum lipid concentrations were not altered in any of the intervention groups. Findings indicate that 2.5 g/day of proteins from fish or milk may be sufficient to improve glucose regulation in overweight adults. The effects were most pronounced after supplementation with proteins from cod, herring and milk, whereas salmon protein did not affect any of the measurements related to glucose regulation. This trial was registered at clinicaltrials.gov as NCT01641055.  相似文献   
995.
Gallibacterium anatis is a major cause of reproductive tract infections in chickens. Here, we aimed to evaluate the efficacy of the recombinant protein GtxA-N at protecting hens, by addressing three objectives; (i) evaluating the antibody response following immunization (ii) scoring and comparing lesions, following challenge with G. anatis, in immunized and non-immunized hens and (iii) investigating if the anti-GtxA-N antibody titre in individual hens correlated with the observed lesions. Two consecutive experiments were performed in hens. In the first experiment hens were immunized with GtxA-N on day 0 and day 14, infected with G. anatis on day 28 and euthanized on day 56. The GtxA-N antibody response was assessed in pooled serum samples throughout the experiment, using an indirect enzyme-linked immunosorbent assay (ELISA). In the second experiment the GtxA-N antibody titres were assessed in individual hens before and after immunization. Subsequently, the hens were inoculated with G. anatis and finally all hens where euthanized and submitted for post mortem examination 48?h after inoculation. Immunization elicited strong antibody responses that lasted at least 8 weeks (P?G. anatis infection were significantly lower in immunized hens compared to non-immunized hens (P?=?.004). Within the immunized group, no correlation was found between the individual antibody titres and the lesion scores. This study clearly demonstrated GtxA-N as a vaccine antigen able of inducing protective immunity against G. anatis.  相似文献   
996.
Previously, we have shown that TNF-α protects iron-exposed J774 macrophages against iron-catalyzed oxidative lysosomal disruption and cell death by increasing reduced glutathione and H-ferritin in cells. Because J774 cells are able to harbor large amounts of iron, which is potentially harmful in a redox-active state, we hypothesized that TNF-α-stimulated J774 macrophages will prevent iron-driven oxidative killing of alveolar epithelial A549 cells in co-culture. In the present study, iron trichloride (which is endocytosed by cells as hydrated iron-phosphate complexes) was mainly deposited inside the lysosomes of J774 macrophages, while A549 cells, equally iron exposed, accumulated much less iron. When challenged by oxidants, however, reactive lysosomal iron in A549 cells promoted lysosomal disruption and cell death, particularly in the presence of TNF-α. This effect resulted from an elevation in ROS generation by TNF-α, while a compensatory upregulation of protective molecules (H-ferritin and/or reduced glutathione) by TNF-α was absent. A549 cell death was particularly pronounced when iron and TNF-α were present in the conditioned medium during oxidant challenge; thus, iron-driven oxidative reactions in the culture medium were a much greater hazard to A549 cells than those taking place inside their lysosomes. Consequently, the iron chelator, deferoxamine, efficiently prevented A549 cell death when added to the culture medium during an oxidant challenge. In co-cultures of TNF-α-stimulated lung cells, J774 macrophages sequestered iron inside their lysosomes and protected A549 cells from oxidative reactions and cell death. Thus, the collective effect of TNF-α on co-cultured lung cells was mainly cytoprotective.  相似文献   
997.
Sexuality and Disability - Hypopituitarism means a partial or complete inability to produce pituitary hormones, including those regulating gonadal function. The condition therefore leads to hormone...  相似文献   
998.

Objectives

There is a need to improve the assessment of emotional functioning (EF). In the international Advance Care Planning: an Innovative Palliative Care Intervention to Improve Quality of Life in Cancer Patients - a Multi-Centre Cluster Randomized Clinical Trial (ACTION) trial involving patients with advanced cancer, EF was assessed by a customized 10-item short form (EF10). The EF10 is based on the European Organisation for Research and Treatment of Cancer (EORTC) EF item bank and has the potential for greater precision than the common EORTC Quality of Life Questionnaire Core 30 four-item scale (EF4). We assessed the relative validity (RV) of EF10 compared with EF4.

Methods

Patients from Belgium, Denmark, Italy, the Netherlands, Slovenia, and the United Kingdom completed EF10 and EF4, and provided data on generic quality of life, coping, self-efficacy, and personal characteristics. Based on clinical and sociodemographic variables and questionnaire responses, 53 “known groups” that were expected to differ were formed, for example, females versus males. The EF10 and EF4 were first independently compared within this known group, for example, the EF10 score of females vs the EF10 score of males. When these differences were significant, the RV was calculated for the comparison of the EF10 with the EF4.

Results

A total of 1028 patients (57% lung, 43% colorectal cancer) participated. Forty-five of the 53 known-groups comparisons were significantly different and were used for calculating the RV. In 41 of 45 (91%) comparisons, the RV was more than 1, meaning that EF10 had a higher RV than EF4. The mean RV of EF10 compared with that of EF4 was 1.41, indicating superior statistical power of EF10 to detect differences in EF.

Conclusions

Compared with EF4, EF10 shows superior power, allowing a 20% to 34% smaller sample size without reducing power, when used as a primary outcome measure.  相似文献   
999.
1000.
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