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   1817篇
  免费   80篇
  国内免费   3篇
耳鼻咽喉   11篇
儿科学   54篇
妇产科学   55篇
基础医学   204篇
口腔科学   20篇
临床医学   163篇
内科学   364篇
皮肤病学   37篇
神经病学   88篇
特种医学   121篇
外科学   362篇
综合类   40篇
预防医学   122篇
眼科学   26篇
药学   105篇
中国医学   6篇
肿瘤学   122篇
  2023年   25篇
  2022年   50篇
  2021年   56篇
  2020年   42篇
  2019年   61篇
  2018年   53篇
  2017年   37篇
  2016年   34篇
  2015年   41篇
  2014年   82篇
  2013年   85篇
  2012年   121篇
  2011年   131篇
  2010年   53篇
  2009年   55篇
  2008年   98篇
  2007年   106篇
  2006年   105篇
  2005年   80篇
  2004年   73篇
  2003年   60篇
  2002年   43篇
  2001年   25篇
  2000年   37篇
  1999年   22篇
  1998年   18篇
  1997年   12篇
  1996年   8篇
  1992年   25篇
  1991年   13篇
  1990年   17篇
  1989年   15篇
  1988年   9篇
  1987年   15篇
  1986年   11篇
  1985年   11篇
  1984年   10篇
  1983年   9篇
  1982年   12篇
  1980年   7篇
  1979年   9篇
  1978年   10篇
  1977年   7篇
  1976年   7篇
  1975年   11篇
  1973年   13篇
  1972年   10篇
  1971年   11篇
  1970年   7篇
  1968年   11篇
排序方式: 共有1900条查询结果,搜索用时 15 毫秒
991.

Introduction

High level evidence to guide surveillance following curative intent treatment for pancreatic cancer is lacking and this has likely resulted in wide variations in practice. We aim to describe patterns of surveillance and evaluate their impact on outcomes.

Methods

A total of 147 adult patients who received at least one cycle of adjuvant gemcitabine or 5-fluorouracil-based chemotherapy at any one of five British Columbia Cancer Agency centers between 2001 and 2015 were included. Surveillance strategies were classified into two categories: discharged to primary care physicians (PCPs) or follow-up at cancer centers (CC) that included regular clinical assessments, laboratory testing, and/or diagnostic imaging.

Results

Median age at diagnosis was 64 (range 38–85) years and 48% were men. More patients were followed by CC than by PCPs (66 vs. 44%). Among the measured prognostic factors, only patients with advanced tumor stage (T3/4) were more likely to be followed by cancer specialists (78 vs. 62%, P = 0.03), while other patient and disease characteristics were balanced between the two groups. In the entire cohort, 100 (68%) patients had a documented recurrence. Patients followed by CC were more likely to receive palliative chemotherapy at recurrence than those followed by PCPs (58 vs. 34%, respectively, P = 0.03). The median overall survival (OS) was 2.82 (95% CI 2.17–3.32) years in the CC group and 3.35 (95% CI 2.85–5.06) years in the PCP group while the median relapse-free survival (RFS) was 1.4 (95% CI 1.37–1.77) and 2.4 (95% CI 2.07–4.59) years, respectively. On multivariate analysis, there was no significant difference in OS between CC and PCP-based surveillance (HR 1.23; 95% CI 0.74–2.04, P = 0.40); however, RFS favored the PCP group (HR 1.62; 95% CI 1.01–2.56, P = 0.04, for the CC group).

Conclusion

In this population-based analysis, surveillance tests and imaging performed by CC detected recurrences earlier when compared to follow-up by PCPs, but this did not result in OS differences. Patients with more advanced tumors were more likely to be seen at CC. PCPs may play a larger role in the follow-up care of selected low risk patients with resected pancreatic cancer.
  相似文献   
992.
Objectives: To detect Leishmania species in human patients, animal reservoirs and Phlebotomus sandflies in Waziristan, Pakistan. Methods: Tissue smears and aspirates from 448 cutaneous leishmaniasis(CL) suspected patients were analyzed. To sort out role of the reservoir hosts, skin scrapings, spleen and liver samples from 104 rodents were collected. Furthermore, buffy coat samples were obtained from 60 domestic animals. Sandflies were also trapped. All human, animals and sandfly samples were tested by microscopy, kinetoplastic PCR and internal transcribed spacer 1(ITS1) PCR followed by restriction fragment length polymorphism for detection of Leishmania species. Results: An overall prevalence of 3.83% and 5.21% through microscopy and ITS1 PCR respectively was found. However, the statistically non-significant correlation was found between area, gender, and number of lesions. The presence of rodents, sandflies, domestic animals and internally displaced people increased the risk of CL. Using ITS1-PCR-RFLP, Leishmania tropica(L. tropica) was confirmed in 106 samples while 25 of the isolates were diagnosed as Leishmania major(L. major). Similarly, 3/104 rodents were positive for L. major and 14 pools of DNA samples containing Phlebotomus sergenti sandflies were positive for L. tropica. None of samples from domestic animals were positive for leishmaniasis. Conclusions: In the present study, L. tropica and L. major are found to be the main causative agents of CL in study area. Movement of internally displaced people from CL endemic areas presents a risk for nearby CL free areas. To the best of our knowledge, we report for the first time L. major infection in rodents(Rattus rattus) and L. tropica in Phlebotomus sergenti sandflies trapped in Waziristan, Pakistan.  相似文献   
993.
Sullivan T  Haider A  DiRusso SM  Nealon P  Shaukat A  Slim M 《The Journal of trauma》2003,55(6):1083-7; discussion 1087-8
BACKGROUND: The Injury Severity Score (ISS) is a widely accepted method of measuring severity of traumatic injury. A modification has been proposed--the New Injury Severity Score (NISS). This has been shown to predict mortality better in adult trauma patients, but it had no predictive benefit in pediatric patients. The aim of this study was to determine whether the NISS outperforms the ISS in a large pediatric trauma population. METHODS: Admissions in the National Pediatric Trauma Registry between April 1996 and September 1999 were included. The ISS and NISS were calculated for each patient. The study endpoints were mortality at hospital discharge, functional outcome in three domains (expression, locomotion, and feeding), and discharge disposition for the survivors. Predictive ability of each score was assessed by area under the receiver operating characteristic curve. RESULTS: The NISS and ISS performed equally well at predicting mortality in patients with lower injury severity (ISS < 25), but the NISS was significantly better at predicting mortality in the more severely injured patients. Both scores performed equally well at predicting expression and feeding ability. The NISS was superior to the ISS in predicting locomotion ability at discharge. Thirty-seven percent of patients had an NISS that was higher than their ISS. These patients had a significantly higher mortality and suffered worse functional outcomes. CONCLUSION: The NISS performs as well as the ISS in pediatric patients with lower injury severity and outperforms the ISS in those with higher injury severity.  相似文献   
994.
OBJECTIVES: We sought to determine whether seropositivity to Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus (CMV) is an independent predictor of incident cardiovascular disease. BACKGROUND: Recent reports have suggested that infections may contribute to risk of cardiovascular disease. However, prospective studies of these associations in a free-living population are lacking. METHODS: We measured serum H. pylori IgG, C. pneumoniae IgG and IgA, and CMV IgG levels in Framingham Heart Study cohort participants. Blood samples were drawn during the 16th biennial examination cycle (1979 to 1982) from 1,187 participants free of cardiovascular disease (mean age 69 years) and stored at -20 degrees C. A pooled primary end point of myocardial infarction, atherothrombotic stroke, and coronary heart disease deaths was studied in relation to serology. Using a Cox model, hazard ratios (HR) and 95% confidence intervals (CI) were calculated, adjusting for age, gender, and established risk factors. RESULTS: Seropositivity to H. pylori IgG, C. pneumoniae IgG, C. pneumoniae IgA, and CMV IgG was 60%, 45%, 11%, and 69%, respectively. During 10 years of follow-up, incident cardiovascular disease occurred in 199 participants (16.8%). In age- and gender-adjusted models, H. pylori IgG (HR 1.09, 95% CI 0.81 to 1.46), C. pneumoniae IgG (HR 0.91, 95% CI 0.68 to 1.20), C. pneumoniae IgA (HR 0.65, 95% CI 0.39 to 1.07), and CMV IgG (HR 0.84, 95% CI 0.62 to 1.12) were not associated with incident cardiovascular disease. These associations were further attenuated after adjustment for risk factors including body mass index, total and high-density lipoprotein cholesterol, diabetes mellitus, smoking, and hypertension. These estimates did not change for the individual components of cardiovascular disease, and seropositivity to more than one organism did not alter these risk estimates substantially. CONCLUSIONS: In this elderly cohort, chronic H. pylori, C. pneumoniae, and CMV infections, as evidenced by seropositivity, were not associated with increased risk for cardiovascular disease. Additional studies are needed to determine the relations of chronic infections to cardiovascular disease risk in younger persons.  相似文献   
995.
The hypothesis is tested, whether increasing language processing demands draw on the capacity of working memory thereby leading to an increase in theta band power. Previous research has shown that theta reflects working memory whereas upper alpha semantic memory demands. Sentences were presented in four chunks in a reading and a semantic task. In the latter, subjects had to find a superordinate concept to a noun presented in the third chunk. The data show an increase in theta during sentence processing which was significantly smaller in the semantic task. In contrast, the upper alpha band exhibited a significantly larger change in band power during the semantic task and that time window in which subjects searched for the superordinate concept. Thus, we conclude that semantic processing does not draw selectively on the capacity of working memory and that different linguistic processes have no direct influence on theta oscillations.  相似文献   
996.
997.
998.
Diminished left ventricular contractility and increased right ventricular afterload are issues in cardiac surgery. The usual administration of catecholamines (epinephrine) via the central venous (CV) catheter increases cardiac output, but also may increase pulmonary vascular constriction. Epinephrine was, therefore, administered via the left atrial (LA) catheter or the CV catheter in 8 cardiac surgery patients, each serving as his or her own control. The LA administration of epinephrine has an advantage with its immediate effect on the coronary circulation, while avoiding associated pulmonary vasoconstriction by passing through the systemic capillary bed before reaching the lung. It was found in this study that administration of epinephrine via an LA catheter increased the average cardiac output by 1.05 L/ min, which was significantly (P < 0.05) greater than with administration via the CV catheter. With LA administration of epinephrine, systemic arterial pressures (systolic arterial pressure and diastolic arterial pressure) (SAP, DAP) were also elevated to a greater extent than by CV administration. On the other hand, pulmonary arterial pressures (systolic pulmonary arterial pressure and diastolic pulmonary arterial pressure) (SPAP, DPAP) were less elevated than by administration via the CV catheter. This produced increased coronary perfusion and a smaller increase in pulmonary vascular tone by LA administration in contrast to CV administration of epinephrine. It is concluded that epinephrine administration via an LA catheter improved myocardial performance and pulmonary perfusion due to direct entry of the agent into the coronary circulation and partial metabolism while passing through the systemic capillary bed before reaching the lung.  相似文献   
999.
The prevalence of human leukocyte antigen (HLA) DR alleles has been determined in 69 Kuwaiti Arab children with juvenile rheumatoid arthritis (JRA) and compared to that in 212 ethnically matched normal healthy controls using a PCR-sequence specific primers (PCR-SSP) method. A very high incidence of DR3 was detected in JRA patients compared to the controls (P < 0.0001, RR = 2.235). The high incidence of HLA-DR3 in JRA patients was accounted for mainly by an excess of DRB1*0307 (P < 0.05, RR = 3.072) and DRB1*0308 (P < 0.009, RR = 2.663) compared to the controls. Moreover, DR3 was more prevalent when patients with ANA-positive JRA were analysed separately; 73% compared to 58% for the whole JRA patient group. The frequency of DR1 was also higher in the JRA group compared to controls (P = 0.019, RR = 3.585). Although the incidence of some alleles was higher in the control group (DR13 and DR7), none reached a statistically significant level. All the patients with iridocyclitis had either a DR1 or DR3 allele, except for one child. The frequency of DRB1*03 was found to be much higher in the polyarticular subtype of Kuwaiti JRA cases compared to the oligoarticular subgroup and the controls. Also, a non-significant increase in the frequency of the DRB1*04, *11 and *15 alleles was detected in the polyarticular subtype of the Kuwaiti JRA cases compared to the controls.  相似文献   
1000.
Rheumatoid arthritis is a chronic inflammatory disease characterized by the destruction of articular cartilage and bone in a chronic phase. Pathology of rheumatoid arthritis suggests autoimmunity linked to inflammation. In our study, rheumatoid arthritis was induced in Wistar rats by intradermal injections of 100 μl of emulsion containing bovine type II collagen in complete Freund’s adjuvant at the base of the tail. Disease developed about 13 ± 1 days after immunization and treatment with hesperidin (HES) at a dose of 160 mg kg?1 body weight was given after onset of disease daily until 20th day. The effect of treatment in the rats was monitored by clinical scoring, biochemical parameters and histological evaluations in joints. A steady increase in the articular elastase, nitric oxide and lipid peroxidation was observed in joints of arthritic rats as compared to control, whereas a significant decrease in reduced glutathione, superoxide dismutase activity and catalase was observed in collagen-induced arthritis rats as compared to control group. The results from the present work indicate that the treatment with hesperidin was effective in bringing about significant changes on all the parameters studied in collagen-induced arthritis rats. These data confirm that erosive destruction of the joint cartilage in collagen-induced arthritis is due free radicals released by activated neutrophils and produced by other biochemical pathways. In the present study, an attempt has been made to amelioration of the disease process by a natural product. These results suggest that oral administration of HES could be effective for treating human 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