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   18670篇
  免费   1191篇
  国内免费   81篇
耳鼻咽喉   179篇
儿科学   596篇
妇产科学   414篇
基础医学   2467篇
口腔科学   370篇
临床医学   2186篇
内科学   4421篇
皮肤病学   527篇
神经病学   1873篇
特种医学   407篇
外科学   1443篇
综合类   100篇
一般理论   9篇
预防医学   1894篇
眼科学   303篇
药学   1278篇
中国医学   69篇
肿瘤学   1406篇
  2023年   152篇
  2022年   129篇
  2021年   532篇
  2020年   329篇
  2019年   525篇
  2018年   643篇
  2017年   404篇
  2016年   485篇
  2015年   549篇
  2014年   771篇
  2013年   997篇
  2012年   1566篇
  2011年   1590篇
  2010年   820篇
  2009年   788篇
  2008年   1297篇
  2007年   1278篇
  2006年   1239篇
  2005年   1238篇
  2004年   1058篇
  2003年   1021篇
  2002年   936篇
  2001年   97篇
  2000年   83篇
  1999年   141篇
  1998年   166篇
  1997年   145篇
  1996年   106篇
  1995年   106篇
  1994年   77篇
  1993年   90篇
  1992年   63篇
  1991年   40篇
  1990年   41篇
  1989年   42篇
  1988年   27篇
  1987年   26篇
  1986年   35篇
  1985年   40篇
  1984年   32篇
  1983年   30篇
  1982年   30篇
  1981年   31篇
  1980年   34篇
  1979年   16篇
  1978年   14篇
  1976年   12篇
  1975年   9篇
  1974年   13篇
  1973年   14篇
排序方式: 共有10000条查询结果,搜索用时 211 毫秒
991.
OBJECTIVE: In the light of the Workers' Food Program (WFP) growth and its recent review of nutritional parameters regulations, the study aimed at evaluating food intake in WFP through dietary assessment of lunch served in the program and workers' nutritional status. METHODS: A cross-sectional study was carried out in a representative sample of workers in Brasilia, Federal District, Brazil. A total of 1,044 subjects who had lunch at 52 food and nutrition units were evaluated. Social-economic and demographic data were collected as well as anthropometric measures for calculating the Body Mass Index. Food intake was assessed by dish weight and direct observation of dish composition. RESULTS: Of all subjects, 43% had excess weight, 33.7% were overweight and 9.3% were obese. Males were most affected. Median lunch energy intake was 515 kcal in women and 736 kcal in men. Median dietary fiber intake was 6.0 g among women and 8.3 g among men, and median cholesterol intake was over 90 mg among subjects with excess weight. CONCLUSIONS: The results indicate that the study population who is often seen as healthy is at nutritional risk. Workers in WFP should be targeted for health promotion strategies using especially nutritionists' skills as educators.  相似文献   
992.
The prevalence of obesity has reached epidemic dimension in industrialized countries and it is known that obesity is associated with increased risk of cardiovascular morbidity and mortality. Commonly, obesity is defined by the Body Mass Index (BMI). However, BMI fails to consider body fat distribution. The relationship between the risk of metabolic-cardiovascular diseases and body fat distribution indices such as the waist-to-hip ratio (WHR) and the waist circumference, rather than measures of the degree of body fatness as expressed by BMI, has long been recognized. Recently, clinical and epidemiological research has found waist circumference to be the best anthropometric indicator of both total body fat and intra-abdominal fat mass. Android or visceral obesity is associated with metabolic syndrome and increased cardiovascular morbidity and mortality through a variety of molecular mechanisms possibly linking the metabolic syndrome to hemostatic and vascular abnormalities. Obesity guidelines suggest the need for weight reduction using behavioural change to reduce caloric intake and increasing physical activity. A realistic goal for weight reduction is to reduce body weight by 5% to 10% over a period of 6 to 12 months. Combined intervention of a low calories diet, increased physical activity, and behaviour therapy provides better outcomes for long-term weight reduction and weight maintenance than programs that use only one or two of these modalities. The drugs used to promote weight loss have been anorexic drugs or appetite suppressants. All classes of anorexic drugs affect neurotransmitters in the brain. The new agent sibutramine has norepinephrine and serotonin effects. Another new agent, orlistat, has a different mechanism of action, the reduction of fat absorption. Weight loss drugs approved by the FDA for long-term use may be useful as an adjunct to diet, physical activity and behaviour therapy for patients with a BMI of > or =30 with no concomitant obesity-related risk factors or diseases, and for patients with a BMI of > or =27 with concomitant obesity-related risk factors or diseases.  相似文献   
993.
BACKGROUND: It is generally acknowledged that calcium excretion is a determinant of bone mineral density. Since data confirming this hypothesis are not conclusive, the present study evaluates the relationship between calcium excretion and volumetric bone mineral density (vBMD) in a sample of general population mostly composed of elderly subjects. METHODS: This relationship was studied in 595 subjects in good health (M/F 302/293), selected from the InCHIANTI population, an epidemiologic survey on aging in Tuscany (Italy). Of these subjects, 432 (72.6%) were 65 years old or older. Trabecular and cortical apparent vBMDs were measured by peripheral quantitative computed tomography at right tibia and standardized to age and body mass index (BMI) in each gender (z-score). RESULTS: Men in the highest tertile of calcium excretion had significantly lower trabecular vBMD, and were more likely to have a trabecular z-score of -1 or less. These results were confirmed in men older than 64 years, but not in women and younger men. Sodium excretion and 25-hydroxycolecalciferol (25(OH)D) were greater in men and women in the highest tertile. No differences among tertiles were observed for cortical vBMD, circulating levels of interleukin-1beta and interleukin-6, and intake of principal nutrients and calcium. The lower levels of vBMD z-score were confirmed in men in the highest tertile of calcium excretion, standardized to creatinine clearance, sodium excretion, plasma calcium, and logarithm of circulating 25(OH)D, and resulted to be associated with calcium excretion at multiple regression analysis in men. CONCLUSION: High calcium excretion is associated with a decreased trabecular BMD in elderly men and may predispose men to trabecular bone loss.  相似文献   
994.
OBJECTIVE: The current study investigates covariation bias (illusory correlation) in the perceived association between happiness and body type, as well as the association between covariation bias and eating disorder symptoms. METHOD: Undergraduate women (n = 186) rated pictures of women on a variety of attributes, including happiness, degree of overweight, and attractiveness. Later, they were asked to judge the level of covariation between these attributes that was present in the stimuli that they had rated. Participants also completed the Eating Disorder Examination-Self-Report Questionnaire (EDE-Q). RESULTS: Participants reported that there was a negative association between weight and happiness in the stimuli that they had rated, even though the true correlation in the data was zero. This covariation bias was stronger among participants with higher levels of eating disorder symptoms. DISCUSSION: The results suggest a cognitive bias that may play a role in maintaining and enhancing concerns about shape and weight in symptomatic women.  相似文献   
995.
PURPOSE: Urinary incontinence after radical prostatectomy is a significant clinical problem. In this prospective study we investigate the effectiveness of early pelvic floor muscle training (PFMT) on a large population, that had undergone radical retropubic prostatectomy (RRP) at our department. METHODS: 300 consecutive patients who had undergone RRP for clinically confined prostate cancer were randomized in two groups after catheter removal. One group of 150 patients took part in a structured PFMT program. This began before discharge and consisted of Kegel exercises. The remaining 150 patients constituted the control group, they were not formally instructed in PFMT. Incontinence was assessed objectively using the 1 hour and 24 hour pad test, as well as with the ICS-Male questionnaire. All patients who were incontinent after 6 months underwent urodynamic evaluation. RESULTS: In the treated group, 19% (29 patients) achieved continence after 1 month, and 94.6% (146 patients) after 6 months. In the control group 8% (12 patients) achieved continence after 1 month, and 65% (97 patients) after 6 months (p<0.001). Patient age did not correlate with continence in the control group (p>0.05), although a significant correlation was revealed within the treated group (p<0.01). Overall, 93.3% of the total population achieved continence after one year. CONCLUSIONS: After RRP an early supportive rehabilitation program like PFMT significantly reduces continence recovery time.  相似文献   
996.
We report a case of hamulus (hook of hamate) fracture nonunion and secondary flexor digitorum profundus tendon rupture caused by repetitive wrist hyperextension sustained during clay shotgun shooting. The hyperextension caused avulsion of the hamulus by the pisohamate ligament. The hamulus was excised and a flexor digitorum profundus tendon transfer of the ring to small finger side to side was performed with satisfactory outcome.  相似文献   
997.
Qualitative assessment of breast reconstruction in a specialist breast unit   总被引:1,自引:0,他引:1  
Nano MT  Gill PG  Kollias J  Bochner MA  Carter N  Winefield HR 《ANZ journal of surgery》2005,75(6):445-53; discussion 371-2
BACKGROUND: Breast reconstruction is an integral part of the surgical management of women with breast cancer. It is often performed by plastic surgeons but, in some centres, it is performed by breast surgeons trained in breast reconstruction and oncoplastic surgery. We evaluated the objective and subjective outcomes of reconstruction for breast cancer at the Royal Adelaide Hospital Breast Unit (Adelaide, Australia) between 1990 and June 2002. METHODS: A chart analysis was conducted of all patients who underwent breast cancer reconstruction at the Royal Adelaide Hospital Breast Unit with analysis of type of reconstruction and complications. Patients were interviewed and self-assessment quality of life questionnaires (FACT-B, body image), and overall satisfaction with reconstruction using an analogue scale were performed. Three observers carried out photographic analysis of the reconstructions. A comparison was then made between the different forms of reconstruction used. RESULTS: One hundred and ninety-two patients underwent a total of 219 breast reconstructions during this period. The reconstructions included 18 latissimus dorsi mini flaps, 83 tissue expander/implants, 43 latissimus dorsi flaps and 75 TRAM flaps. There were no perioperative deaths. Significant systemic complications occurred in four patients (2%). Significant implant related complications occurred in four patients (3.2% of patients with implants). Total flap loss occurred in four patients (2.9% of flaps). One hundred and twenty-three patients were able to be contacted and completed the questionnaires. Overall 77% of patients were highly satisfied with breast reconstruction and 82% scored a satisfactory result on photographic analysis. All four forms of reconstruction rated highly with respect to quality of life, body image, patient satisfaction and photographic assessment. CONCLUSIONS: Breast reconstruction undertaken by breast surgeons trained in breast reconstruction and oncoplastic techniques has been performed with an acceptable rate of complications and a high level of patient satisfaction. Satisfaction with breast reconstruction was similar across the four methods of reconstruction used.  相似文献   
998.
BACKGROUND: Current surgical treatment modalities for breast cancer include breast conserving surgery, mastectomy alone and mastectomy with breast reconstruction. There are recognized benefits of breast conservation and breast reconstruction over mastectomy but there are few studies assessing this area in Australia. The aim of the present study was to compare the various surgical strategies for breast cancer treatment in terms of quality of life, cosmesis and patient satisfaction. METHODS: A chart analysis was conducted of all patients who underwent Breast Cancer Reconstruction at the Royal Adelaide Hospital Breast Unit between 1990 and 2002. Patients were then traced and asked to take part in an interview. Mastectomy and breast conservation patients who attended outpatient clinic for follow up were also approached. All three groups were interviewed and self-assessment quality of life questionnaires (Functional Assessment of Cancer Therapy-Breast, body image) were administered. The breast conservation and reconstruction groups also underwent assessment of satisfaction and cosmesis. RESULTS: A total of 78 mastectomy, 109 breast conservation and 123 breast reconstruction patients were interviewed. Quality of life assessment was similar between the three groups but the breast conservation and reconstruction patients' body image scores were superior to the mastectomy group. Patient satisfaction was higher in the reconstruction group than the breast conservation group of patients, while cosmesis was similar. CONCLUSION: While little difference was seen on quality of life assessment, body image is improved with the use of breast conservation and reconstruction. The high satisfaction and cosmesis scores in the breast reconstruction group are an indication of the superior results that can be achieved with breast reconstruction.  相似文献   
999.
Our objectives were to establish the incidence and progression of stenotic lesions in the contralateral carotid artery (CCA) after endarterectomy, to identify subpopulations of patients at risk of contralateral disease progression, and to evaluate the efficacy of duplex scanning surveillance at detecting these lesions. We performed a prospective study on 180 patients in whom the CCA to the operated artery was healthy or showed <70% stenosis. All patients had completed a clinical and hemodynamic follow-up program, including duplex scanning of both carotids, with sessions 3 and 6 months after surgery and then every semester until 2 years. Thereafter, examinations were scheduled according to the severity of stenosis. Mean follow-up time was 26.2 months (range 1.6-67.6). Disease progression was observed in 26 lesions (15%), nine of which (5.5%) progressed to severe stenosis (SS). Kaplan-Meier event-free rates of any disease progression were 89%, 88%, 82%, and 79% for 1, 2, 3, and 4 years, respectively. Event-free rates of progression to SS were 98%, 96%, 93%, and 90.6%, respectively, for 1, 2, 3, and 4 years. The risk of progression to SS was five times higher for stenoses that were moderate at the start of the study (p = 0.025). Severe contralateral stenoses were more common and appeared later during follow-up than ipsilateral restenoses. Progression of contralateral stenotic lesions is not uncommon and is essentially related to the presence of a moderate lesion at the start of follow-up. Indeed, moderate stenosis is a risk factor for progression to SS, which appears later and more frequently than ipsilateral restenosis. It therefore seems that patients with a moderate contralateral lesion would benefit from long-term duplex ultrasound surveillance.  相似文献   
1000.
PURPOSE: Obstructive uropathies, including posterior urethral valves (PUVs) and kidney hypodysplasia, are the most frequent cause of renal failure in children. The role of renin-angiotensin system genes in renal and urinary tract development has been observed in experimental models. The aim of this study was to investigate the distribution of angiotensin converting enzyme (ACE), angiotensinogen (AGT) and angiotensin receptor type 1 (ATR1) genetic polymorphisms in children affected by chronic renal failure due to renal hypodysplasia associated with posterior urethral valves or without urethral abnormalities. MATERIALS AND METHODS: The study included 50 children (21 with hypodysplasia associated with PUVs, 7 with obstructive uropathy and 22 with pure hypodysplasia) and 50 healthy subjects matched for sex and geographic origin. ACE ID, AGT TC and ATR1 AC gene polymorphisms were assayed in all patients with standard polymerase chain reaction techniques. RESULTS: ACE II was expressed more in patients with PUVs compared to those with other dysplasias and controls (43% vs 7% and 10%, respectively, chi-square test p <0.05), while ATR1 AA was significantly less represented in patients with hypodysplasia compared to controls (38% vs 56%, chi-square test p <0.05). ACE DD and AGT genotypes were not distributed differently in patients with PUVs compared to those with other dysplasias and controls. CONCLUSIONS: To our knowledge this is the first report associating severe congenital uropathies and renal hypodysplasia with decreased renin-angiotensin system activity associated with the ACE II genotype and a possible functional imbalance among ATR1 receptors.  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