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   2217篇
  免费   197篇
  国内免费   7篇
耳鼻咽喉   37篇
儿科学   88篇
妇产科学   30篇
基础医学   243篇
口腔科学   42篇
临床医学   281篇
内科学   447篇
皮肤病学   28篇
神经病学   209篇
特种医学   256篇
外科学   243篇
综合类   53篇
一般理论   3篇
预防医学   192篇
眼科学   32篇
药学   98篇
中国医学   5篇
肿瘤学   134篇
  2021年   29篇
  2020年   18篇
  2019年   32篇
  2018年   47篇
  2017年   29篇
  2016年   31篇
  2015年   36篇
  2014年   45篇
  2013年   56篇
  2012年   65篇
  2011年   68篇
  2010年   66篇
  2009年   88篇
  2008年   74篇
  2007年   72篇
  2006年   62篇
  2005年   59篇
  2004年   59篇
  2003年   62篇
  2002年   52篇
  2001年   69篇
  2000年   65篇
  1999年   49篇
  1998年   66篇
  1997年   66篇
  1996年   77篇
  1995年   58篇
  1994年   61篇
  1993年   60篇
  1992年   58篇
  1991年   45篇
  1990年   40篇
  1989年   68篇
  1988年   63篇
  1987年   57篇
  1986年   51篇
  1985年   43篇
  1984年   32篇
  1983年   29篇
  1982年   32篇
  1981年   22篇
  1980年   16篇
  1979年   15篇
  1978年   14篇
  1977年   21篇
  1976年   24篇
  1975年   21篇
  1971年   16篇
  1970年   12篇
  1969年   15篇
排序方式: 共有2421条查询结果,搜索用时 15 毫秒
91.
非酒精性脂肪性肝炎(non—alcoholicsteatohepatitis,NASH)现已成为肝移植愈来愈重要的基础肝病。鉴于晚期NASH患者常并存多种影响肝移植转归的临床问题,而至今尚无针对NASH患者进行肝移植的评估和治疗指南,为此英国移植学会(British Transplant Society,BTS)邀请相关专家制定了指南,以指导肝移植前后NASH患者的处理。  相似文献   
92.
Urosepsis is defined as sepsis caused by a urogenital tract infection. Urosepsis in adults comprises approximately 25% of all sepsis cases, and is in most cases due to complicated urinary tract infections. The urinary tract is the infection site of severe sepsis or septic shock in approximately 10–30% of cases. Severe sepsis and septic shock is a critical situation, with a reported mortality rate nowadays still ranging from 30% to 40%. Urosepsis is mainly a result of obstructed uropathy of the upper urinary tract, with ureterolithiasis being the most common cause. The complex pathogenesis of sepsis is initiated when pathogen or damage‐associated molecular patterns recognized by pattern recognition receptors of the host innate immune system generate pro‐inflammatory cytokines. A transition from the innate to the adaptive immune system follows until a TH2 anti‐inflammatory response takes over, leading to immunosuppression. Treatment of urosepsis comprises four major aspects: (i) early diagnosis; (ii) early goal‐directed therapy including optimal pharmacodynamic exposure to antimicrobials both in the plasma and in the urinary tract; (iii) identification and control of the complicating factor in the urinary tract; and (iv) specific sepsis therapy. Early adequate tissue oxygenation, adequate initial antibiotic therapy, and rapid identification and control of the septic focus in the urinary tract are critical steps in the successful management of a patient with urosepsis, which includes early imaging, and an optimal interdisciplinary approach encompassing emergency unit, urological and intensive‐care medicine specialists.  相似文献   
93.
94.
Child Psychiatry & Human Development - This study evaluated the psychometric properties of the Persian version of the Obsessive–Compulsive Inventory–Child Version (OCI-CV) in...  相似文献   
95.
Skin samples were taken from 10 experimental cattle exposed naturally, during a period extending over two winters, to Bovicola bovis and Solenoptes capillatus, five becoming infested and five being protected from infestation by repeated treatment with ectoparasiticides. Skin sections were examined histopathologically and immunohistochemically for expression of the immune cell markers CD3, CD4, CD8 and class II antigens of the major histocompatibility complex (MHC). Louse-infested cattle had a mixed infiltration of the superficial dermis and perifollicular regions with eosinophils and mononuclear cells. The skin of infested cattle differed from that of non-infested cattle in showing significantly more cells expressing CD3, CD4 and MHC class II (P<0.05). Many of the MHC class II(+) cells had dendritic morphology, suggesting active antigen presentation within the lesions. Louse infestations have previously been thought to produce a type 1 hypersensitivity response, mediated by Th2 lymphocytes. However, the increased number of lymphocytes and antigen-presenting cells observed in the present study suggests that in chronic infestation there is activation of local cell-mediated (Th1) immunity.  相似文献   
96.
97.

Aims

Patients hospitalized for heart failure (HF) are at high risk for 30‐day readmission. This study sought to examine the timings and causes of readmission within 30 days of an HF hospitalization.

Methods and results

Timing and cause of readmission in the ASCEND‐HF (Acute Study of Clinical Effectiveness of Nesiritide and Decompensated Heart Failure) trial were assessed. Early and late readmissions were defined as admissions occurring within 0–7 days and 8–30 days post‐discharge, respectively. Patients who died in hospital or remained hospitalized at day 30 post‐randomization were excluded. Patients were compared by timing and cause of readmission. Logistic and Cox proportional hazards regression analyses were used to identify independent risk factors for early vs. late readmission and associations with 180‐day outcomes. Of the 6584 patients (92%) in the ASCEND‐HF population included in this analysis, 751 patients (11%) were readmitted within 30 days for any cause. Overall, 54% of readmissions were for non‐HF causes. The median time to rehospitalization was 11 days (interquartile range: 6–18 days) and 33% of rehospitalizations occurred by day 7. Rehospitalization within 30 days was independently associated with increased risk for 180‐day all‐cause death [hazard ratio (HR) 2.38, 95% confidence interval (CI) 1.93–2.94; P < 0.001]. Risk for 180‐day all‐cause death did not differ according to early vs. late readmission (HR 0.99, 95% CI 0.67–1.45; P = 0.94).

Conclusions

In this hospitalized HF trial population, a significant majority of 30‐day readmissions were for non‐HF causes and one‐third of readmissions occurred in the first 7 days. Early and late readmissions within the 30‐day timeframe were associated with similarly increased risk for death. Continued efforts to optimize multidisciplinary transitional care are warranted to improve rates of early readmission.
  相似文献   
98.
To understand the hematopoietic and nonhematopoietic responses to interleukin-3 (IL-3), expression of cell-surface IL-3 receptors (IL-3R) was examined on bone marrow (BM) cells and peripheral blood (PB) cells of rhesus monkeys during the course of in vivo IL-3 treatment. Whereas IL-3R expression is low in untreated monkeys, IL-3 administration led to a gradual increase in both low- and high-affinity binding sites for IL-3. This increase reflected the total number of cells expressing IL- 3Rs, as detected by flow cytometry using biotinylated IL-3. Most of these IL-3R+ cells in both BM and PB could be characterized as basophilic granulocytes that contained high levels of histamine. In contrast to the effect on these differentiated cells, IL-3 administration did not significantly alter the low level IL-3R expression on immature, CD34+ cells. Further flow cytometric analysis using biotinylated growth factors showed that the IL-3R+ basophils also expressed receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), but not for IL-6 or Kit ligand. These findings indicated that the IL-3R+ cells included neither monocytes, which express GM-CSFRs and IL-6Rs abundantly, nor mast cells, which express c- kit. By combining flow cytometric and Scatchard data, it was calculated that the basophils contain as many as 1 to 2 x 10(3) high-affinity IL- 3Rs and 15 to 30 x 10(3) low-affinity sites. The finding that in vivo IL-3 treatment leads to the production of large numbers of cells that express high levels of IL-3R and are capable of producing histamine provides an explanation for the often severe allergic reactions that occur during prolonged IL-3 administration. It also indicates that IL- 3, in addition to its direct effects on hematopoietic cells, may also stimulate hematopoiesis through the release of secondary mediators such as histamine by IL-3-responsive mature cells.  相似文献   
99.
A group of hypertensive patients (n = 2855) with an untreated diastolic blood pressure greater than or equal to 90 mmHg were followed in the Department of Health and Social Security (DHSS) Hypertension Care Computing Project (DHCCP) for periods of up to 10 years. During this period 191 of these patients died. Survival was assessed in relation to pretreatment blood pressure levels and blood pressure achieved during treatment. The blood pressure during treatment was a useful predictor of mortality, but the pretreatment pressure was not. After adjusting for age, mortality was particularly related to the height of the systolic and diastolic blood pressure during the second and third years of treatment. In men, age-standardized 5-year mortality was greater than 10% in those with a first year treated systolic pressure greater than 150 mmHg or a diastolic pressure greater than 95 mmHg. In women, age standardized 5-year mortality was greater than 5% with the same levels of treated blood pressure. The longest survival occurred with the lowest bands of treated pressure, i.e. systolic pressure less than 140 and diastolic pressure less than 90 mmHg; the 5-year mortality being less than 7% in men and less than 3% in women. Treated systolic and diastolic pressures were useful in predicting death from ischaemic heart disease (IHD).  相似文献   
100.
The pufferfish Fugu rubripes has a genome ≈7.5 times smaller than that of mammals but with a similar number of genes. Although conserved synteny has been demonstrated between pufferfish and mammals across some regions of the genome, there is some controversy as to what extent Fugu will be a useful model for the human genome, e.g., [Gilley, J., Armes, N. & Fried, M. (1997) Nature (London) 385, 305–306]. We report extensive conservation of synteny between a 1.5-Mb region of human chromosome 11 and <100 kb of the Fugu genome in three overlapping cosmids. Our findings support the idea that the majority of DNA in the region of human chromosome 11p13 is intergenic. Comparative analysis of three unrelated genes with quite different roles, WT1, RCN1, and PAX6, has revealed differences in their structural evolution. Whereas the human WT1 gene can generate 16 protein isoforms via a combination of alternative splicing, RNA editing, and alternative start site usage, our data predict that Fugu WT1 is capable of generating only two isoforms. This raises the question of the extent to which the evolution of WT1 isoforms is related to the evolution of the mammalian genitourinary system. In addition, this region of the Fugu genome shows a much greater overall compaction than usual but with significant noncoding homology observed at the PAX6 locus, implying that comparative genomics has identified regulatory elements associated with this gene.  相似文献   
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