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   3066篇
  免费   191篇
  国内免费   5篇
耳鼻咽喉   18篇
儿科学   167篇
妇产科学   41篇
基础医学   435篇
口腔科学   74篇
临床医学   257篇
内科学   681篇
皮肤病学   25篇
神经病学   416篇
特种医学   72篇
外科学   471篇
综合类   16篇
预防医学   150篇
眼科学   39篇
药学   225篇
中国医学   8篇
肿瘤学   167篇
  2023年   20篇
  2022年   40篇
  2021年   89篇
  2020年   54篇
  2019年   90篇
  2018年   80篇
  2017年   52篇
  2016年   49篇
  2015年   66篇
  2014年   81篇
  2013年   123篇
  2012年   202篇
  2011年   212篇
  2010年   131篇
  2009年   124篇
  2008年   171篇
  2007年   163篇
  2006年   169篇
  2005年   145篇
  2004年   116篇
  2003年   134篇
  2002年   117篇
  2001年   78篇
  2000年   85篇
  1999年   71篇
  1998年   40篇
  1997年   26篇
  1996年   24篇
  1995年   26篇
  1994年   17篇
  1993年   11篇
  1992年   36篇
  1991年   25篇
  1990年   39篇
  1989年   35篇
  1988年   32篇
  1987年   32篇
  1986年   26篇
  1985年   20篇
  1984年   19篇
  1983年   14篇
  1982年   18篇
  1981年   10篇
  1980年   10篇
  1979年   10篇
  1978年   15篇
  1976年   8篇
  1975年   8篇
  1973年   10篇
  1971年   8篇
排序方式: 共有3262条查询结果,搜索用时 15 毫秒
121.
122.
BackgroundA surveillance program was performed in colorectal cancer (CRC) patients after surgery, to diagnose asymptomatic recurrence.AimsTo assess whether 18-FDG positron emission tomography/CT (PET/CT) improved the detection of recurrence during a 3-year follow-up.MethodsA multicentre, two-arm randomised prospective trial comparing different 36-month follow-up strategies. Complete colonoscopy was performed at baseline and after 3 years and clinical exams with imaging every 3 months. The conventional arm (A) received carcinoembryonic antigen, liver echography, and alternated between lung radiography and computed tomography (CT) scans. The experimental arm (B) received PET/CT.ResultsA total of 365 patients with colon (79.4%) or rectal cancer (20.6%), stages II (48.2%) or III (50.8%), were enroled in this study. At 36 months, intention-to-treat analysis revealed recurrence in 31 (17.2%) patients in arm A and 47 (25.4%) in arm B (p = 0.063). At 3 years, 7 of 31 relapses (22.5%) in arm A were surgically treated with curative intent, compared to 17 of 47 (36.2%) in arm B (p = 0.25). The rates of recurrence and new cancers were higher in arm B than arm A (p = 0.038).ConclusionsPET/CT follow-up every 6 months did not increase the rate of recurrence at 3 years or the rate of surgically treated recurrence compared with conventional follow-up.  相似文献   
123.
124.
STUDY OBJECTIVES: This study examines long-term trends in incidence rates of hospitalized pulmonary sarcoidosis in a large cohort of Navy personnel, and evaluates the possible relationship of sarcoidosis with occupation. DESIGN: Incidence rates of first hospitalizations were determined for black and white male Navy enlisted personnel on active duty from 1975 to 2001. SETTING: Navy service includes a potential for exposure to a variety of substances, including nonskid coatings used on ship decks that may be aerosolized during removal. Particulate matter containing aluminum, titanium, and silicates has been identified in nonskid samples. Specific occupational groups may have had greater exposure potential than others. PATIENTS OR PARTICIPANTS: Hospitalized cases included sarcoidosis (n = 674), asthma (n = 3,536), emphysema and chronic bronchitis (n = 1,103), respiratory conditions due to fumes and vapors (n = 61), and pneumoconiosis (n = 51) observed in 9,953,607 person-years of active-duty service. INTERVENTIONS: None. However, improvements were made in personal protective gear and other countermeasures to prevent or limit respiratory exposures during service. MEASUREMENTS AND RESULTS: Annual overall hospitalized sarcoidosis incidence rates per 100,000 were 24.9 for black men and 3.5 for white men (black/white ratio of 7.1, p < 0.0001). Annual incidence rates in blacks declined markedly, particularly since 1989, but the black/white ratio remained high through 1999. Occupational associations were present in blacks and whites. Black ship's servicemen (23 cases) and aviation structural mechanics specializing in structures (12 cases) had more than twice the expected incidence rate compared to all blacks, and white mess management specialists (15 cases) had twice the overall white incidence rate. CONCLUSIONS: There was a steep decline in incidence of hospitalized sarcoidosis in blacks in the Navy. Occupational associations suggest the possibility that a dust or moisture-related lung disease may have been erroneously classified as sarcoidosis, or, alternatively, that sarcoidosis had a previously unrecognized occupational component.  相似文献   
125.
OBJECTIVES: To evaluate multislice computed tomography (MSCT) as an alternative to coronary angiography, we prospectively studied its diagnostic accuracy for the detection of significant coronary artery lesions in patients with significant aortic valve stenosis undergoing valve surgery. BACKGROUND: In patients with aortic valve stenosis, coronary angiography is still recommended before surgery. Multislice computed tomography is a promising noninvasive technique for the detection of significant coronary artery lesions. METHODS: Fifty-five consecutive patients scheduled for coronary angiography in the preoperative assessment of aortic valve stenosis underwent 16-slice MSCT 24 h before coronary angiography. We analyzed coronary lesions, image quality, and arterial calcium score. RESULTS: The sensitivity of the MSCT-based strategy in detecting significant stenosis was 100%, and its specificity 80%. The positive and negative predictive values were respectively 55% and 100%. For calcium scores <1,000 (77% of patients), MSCT detected all patients without coronary artery disease, enabling conventional coronary angiography to be avoided in 35 of 55 cases (80%). For calcium scores >1,000, MSCT enabled conventional coronary angiography to be avoided in only 6% of cases, either because significant stenosis was found with a possible indication of revascularization, or because the examination was not interpretable. CONCLUSIONS: The results of this initial experience in relatively few patients suggest that MSCT-based coronary angiography may serve as an alternative to invasive coronary angiography to rule out significant coronary artery disease in patients scheduled for elective aortic valve replacement. Larger studies are necessary to fully explore the potential of coronary MSCT to improve preoperative risk stratification.  相似文献   
126.
During an influenza A(H7N7) virus outbreak among poultry in Italy during August–September 2013, infection with a highly pathogenic A(H7N7) avian influenza virus was diagnosed for 3 poultry workers with conjunctivitis. Genetic analyses revealed that the viruses from the humans were closely related to those from chickens on affected farms.  相似文献   
127.
Social representations of addiction and the resulting stigmatization have been widely described and studied in the literature, but their effects are no less problematic. These representations, which also occur in care settings, generate a climate of distrust which damages the therapeutic relationship, and its ethical quality. This article, combining clinical experience and an ethical stance, offers an original, innovating approach to the existence of distrust in care relationships in the area of addiction. Pragmatic approaches deriving from the human sciences and analytical philosophy provide an invitation to escape from the demanding climate of mistrust, and to take the gamble on trust so as to improve the quality of interactions between protagonists in care. In complementary fashion, a sociology of action can combat the disquiet generated by distrust through a new commitment to innovating forms of action. This “poetic” mode of action is legitimized by the reflection that backs it up, and by its presentation to peers qualified to approve it. Finally, continental moral philosophy underlines the importance of a carefully weighed commitment on the part of caregivers and addicted patients towards promises aiming to support a sincere care relationship, without damaging the therapeutic dynamic or the ethical quality by providing too many safety nets. This reflection is intended to achieve better identification of the clinical and ethical issues raised by mistrust, and inclusion of these aspects in the training of personnel and in care provision planning.  相似文献   
128.
129.
130.
Objectives. Increasing 25-hydroxyvitamin D serum levels can prevent a wide range of diseases. There is a concern about increasing kidney stone risk with vitamin D supplementation. We used GrassrootsHealth data to examine the relationship between vitamin D status and kidney stone incidence.Methods. The study included 2012 participants followed prospectively for a median of 19 months. Thirteen individuals self-reported kidney stones during the study period. Multivariate logistic regression was applied to assess the association between vitamin D status and kidney stones.Results. We found no statistically significant association between serum 25-hydroxyvitamin D and kidney stones (P = .42). Body mass index was significantly associated with kidney stone risk (odds ratio = 3.5; 95% confidence interval = 1.1, 11.3).Conclusions. We concluded that a serum 25-hydroxyvitamin D level of 20 to 100 nanograms per milliliter has no significant association with kidney stone incidence.An issue of possible concern related to the use of vitamin D supplementation is a reported increase in risk of kidney stones.1 Mounting evidence indicates that a 25-hydroxyvitamin D (25[OH]D) serum level in the range of 40 to 60 nanograms per milliliter (ng/mL) is needed for substantial reduction in risk of a wide range of diseases including breast cancer,2 colorectal cancer,3 multiple sclerosis,4 and type 1 diabetes.5,6 However, few people can achieve 25(OH)D in the range higher than 40 ng/mL without supplementation.7GrassrootsHealth is a nonprofit public health research organization that runs a large population cohort study of participants who reach and sustain, if desired, a 25(OH)D serum level of their choice and tracking subsequent health outcomes. GrassrootsHealth has assembled a database that includes information on serum 25(OH)D concentrations, demographic characteristics, and health status measures. These data include values from 5552 individuals with daily supplemental intakes averaging 3600 international units (IU) per day and an average 25(OH)D level of 45 ng/mL, which is higher than the ranges found in most other cohorts.2,4In this study we investigated whether serum 25(OH)D concentration in the range of 20 to 100 ng/mL was associated with incidence of kidney stones in all participants who provided data at 2 or more sampling times.  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