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   5223篇
  免费   432篇
  国内免费   9篇
耳鼻咽喉   33篇
儿科学   102篇
妇产科学   141篇
基础医学   940篇
口腔科学   104篇
临床医学   523篇
内科学   961篇
皮肤病学   184篇
神经病学   783篇
特种医学   196篇
外科学   487篇
综合类   44篇
一般理论   4篇
预防医学   348篇
眼科学   138篇
药学   273篇
中国医学   8篇
肿瘤学   395篇
  2024年   21篇
  2023年   104篇
  2022年   161篇
  2021年   240篇
  2020年   169篇
  2019年   218篇
  2018年   245篇
  2017年   193篇
  2016年   251篇
  2015年   252篇
  2014年   280篇
  2013年   319篇
  2012年   505篇
  2011年   480篇
  2010年   239篇
  2009年   219篇
  2008年   311篇
  2007年   257篇
  2006年   260篇
  2005年   239篇
  2004年   168篇
  2003年   181篇
  2002年   135篇
  2001年   15篇
  2000年   11篇
  1999年   14篇
  1998年   26篇
  1997年   23篇
  1996年   17篇
  1995年   11篇
  1994年   14篇
  1993年   5篇
  1992年   6篇
  1991年   5篇
  1990年   4篇
  1988年   3篇
  1986年   6篇
  1985年   3篇
  1983年   4篇
  1981年   4篇
  1980年   2篇
  1979年   3篇
  1976年   2篇
  1972年   2篇
  1964年   2篇
  1962年   2篇
  1961年   2篇
  1933年   4篇
  1931年   2篇
  1926年   5篇
排序方式: 共有5664条查询结果,搜索用时 10 毫秒
41.
42.
OBJECTIVE: We investigated whether gestational diabetes mellitus is associated with monocyte-chemoattractant-protein-1 (MCP-1) and soluble CD40 ligand (sCD40L), the functional relevant proteins in the inflammatory process. METHODS: In all 32 women with gestational diabetes mellitus, 18 women without gestational diabetes mellitus and 40 nonpregnant women were included. MCP-1 and sCD40L were measured at the time of the oral glucose tolerance test (second trimester), in the third trimester and postpartum. RESULTS: MCP-1 was higher in pregnant women (women with gestational diabetes mellitus and without) than in nonpregnant women (p < 0.001) in the third trimester, and also in the second trimester and postpartum. MCP-1 was elevated in patients with gestational diabetes mellitus in the third trimester compared to healthy pregnant women (p = 0.007). In gestational diabetes mellitus, MCP-1 increased from the second to the third trimester (p = 0.003). We found no association of sCD40L and gestational diabetes mellitus. CONCLUSION: The elevation of MCP-1 in the third trimester in gestational diabetes mellitus suggests an association between inflammation and GDM. Copyright (c) 2008 John Wiley & Sons, Ltd.  相似文献   
43.
44.
Increasing demand for energy-efficient means of transport has steadily intensified the trend towards lightweight components. Thermoplastic glass fiber composites (organo sheets) play a major role in the production of functional automotive components. Organo sheets are cut, shaped and functionalized by injection molding to produce hybrid components, such as those used in car door modules. The cutting process produces a considerable amount of production waste, which has thus far been thermally recycled. This study develops a closed mechanical recycling process and analyzes the different steps of the process. The offcuts were shredded using two shredding methods and implemented directly in the injection-molding process. Using tensile tests and impact bending tests, the material properties of the recycled materials were compared with the virgin material. In addition, fiber length degradation via the injection-molding process and the influence of the waterjet-cutting process on the mechanical properties are investigated. Recycled offcuts are both comparable to new material in terms of mechanical properties and usability, and are also economically and ecologically advantageous. Recycling polypropylene waste with glass fiber reinforcement in a closed loop is an effective way to reduce industrial waste in a sustainable and economical production process.  相似文献   
45.
Background Delivering high-quality palliative and end-of-life care for cancer patients poses major challenges for health services. We examine the intensity of cancer care in England in the last year of life.Methods We included cancer decedents aged 65+ who died between January 1, 2010 and December 31, 2017. We analysed healthcare utilisation and costs in the last 12 months of life including hospital-based activities and primary care.Results Healthcare utilisation and costs increased sharply in the last month of life. Hospital costs were the largest cost elements and decreased with age (0.78, 95% CI: 0.73–0.72, p < 0.005 for age group 90+ compared to age 65–69 and increased substantially with comorbidity burden (2.2, 95% CI: 2.09–2.26, p < 0.005 for those with 7+ comorbidities compared to those with 1–3 comorbidities). The costs were highest for haematological cancers (1.45, 95% CI: 1.38–1.52, p < 0.005) and those living in the London region (1.10, 95% CI: 1.02–1.19, p < 0.005).Conclusions Healthcare in the last year of life for advanced cancer patients is costly and offers unclear value to patients and the healthcare system. Further research is needed to understand distinct cancer populations’ pathways and experiences before recommendations can be made about the most appropriate models of care.Subject terms: Cancer, Cancer  相似文献   
46.
OBJECTIVE: The purpose of this retrospective study was to present 7 years of data from operations of currently active, chronic venous leg ulcers (CEAP: C6), focusing on the short- and long-term effects of healing and recurrence and considering concomitant risk factors. METHODS: Between January 1997 and March 2004, 173 patients (239 legs) with a currently active, chronic venous leg ulcer were surgically treated. The surgical procedures included two main steps: (1) the surgical interruption of reflux in the superficial and perforating veins to reduce venous hypertension in the entire leg and/or the affected area and (2) the surgical procedure involving the ulcer. A total of 123 patients (173 legs) who came to the follow-up were examined. The follow-up period ranged from 3 months to 7 years. The data collection integrated a preoperative examination that included medical history and clinical diagnoses and incorporated measurements such as body mass index, ankle-brachial pressure index, and the neutral position method at the follow-up. The function of the veins was measured with duplex ultrasonography. Finally, the data were analyzed by using various statistical methods, including Kaplan-Meier analysis, Cox regression analysis, and paired t tests. RESULTS: Initially, ulcer healing occurred in 87% of the cases (151 legs). A total of 13% (22 legs) of the venous ulcers never healed, and recurrent venous ulcers occurred in 5% (9 legs). The Kaplan-Meier analyses of ulcer healing showed a healing rate of 85% in 6 months for all legs. The mean time of healing was 1.5 months. Furthermore, the Kaplan-Meier analyses of ulcer recurrence showed a 1.7% rate of recurrence in 6 months for all legs. The 5-year ulcer recurrence rate was 4.6%. The mean time of recurrence was 70.4 months. CONCLUSIONS: On the basis of the results from the 7 years of data from functional surgery of venous leg ulcers and as a result of the outcomes of our study, we recommend surgical treatment of venous leg ulcers at any stage. We therefore conclude that surgery is indicated before an ulcer is intractable to treatment. In general, our findings are based on the understanding and identification of the causes and symptoms of venous ulceration and illustrate that standard surgical methods can be applied for the therapy of venous leg ulcers at any stage.  相似文献   
47.

Objectives

In addition to routinely administered long-term medication, complex drug regimens of nursing home residents often include as needed or pro re nata (PRN) medication. However, there has been no systematic evaluation of the frequency and concomitants of PRN medication in nursing homes. The main objective of this systematic review was to provide a current assessment of PRN drug use in nursing homes.

Design

A systematic literature search was performed. Data were identified from 4 electronic bibliographic databases: MEDLINE, Embase, CINAHL, and Scopus. Studies were included if they reported quantitative data on PRN drug use in nursing home residents.

Results

Our search strategy resulted in 484 hits, of which 27 articles satisfied the inclusion criteria. The mean number of PRN drugs ranged between 0.4 and 4.9 per resident with a median of 2.5. The proportion of residents prescribed at least 1 PRN drug was between 48.4% and 97.4% (median = 74.9). Administration of prescribed PRN medication was rather low as the proportion of residents with administered PRN drugs ranged from 28% to 55%. Frequently prescribed PRN drugs were analgesics, laxatives, and sedatives. Advanced age, dementia, a higher number of regularly scheduled medications, and length of stay in the nursing home were associated with higher use of PRN drugs.

Conclusions/Implications

Although not regularly administered, PRN drug use in nursing home residents should be taken into account as part of complex drug regimens. In that sense, there seems to be an inadequate number of studies reporting on it. When screening tools like the Beers Criteria are adapted, PRN drugs should be included.  相似文献   
48.
49.
50.
Macrophage inflammatory protein-1alpha (MIP-1alpha) is an interesting chemokine because in addition to its variety proinflammatory activities including chemotaxis and immunomodulation, it is a potent inhibitor of hematopoetic stem cell proliferation. Inhibition of erythroid progenitor cells due to MIP-1alpha or other cytokines can play a role in the pathogenesis of anemia which is one of the most common extra-articular features of active rheumatoid arthritis (RA). In 84 patients with RA, serological and immunological parameters were assessed to detect inflammatory mechanisms and anemia in relation to the serum concentrations of MIP-1alpha. All patients fulfilled the ACR criteria for the diagnosis of a definite or classic RA. We used a quantitative enzyme immuno assay for the detection of MIP-1alpha as well as for the measurement of the acute phase protein serum amyloid A (SAA), the erythropoiesis inducer erythropoietin (EPO) and the transferrin receptor (TfR). The immune activation marker neopterin was measured radioimmunologically. Half of the patients with RA were anemic with hemoglobin values below 12 g/dl. MIP-1alpha was found to be elevated significantly in serum of patients with active rheumatoid arthritis and in patients with anemia. Most of the anemic patients with markedly elevated acute phase reactions had an anemia with chronic diseases and not a functional iron deficiency alone. TfR correlated with EPO. The results show that enhanced expression of MIP-1alpha is indicative of systemic inflammation in RA. Moreover, besides the regulation of inflammatory processes, this chemokine may influence the pathogenesis of anemia in RA patients.  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