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   108663篇
  免费   6129篇
  国内免费   655篇
耳鼻咽喉   1069篇
儿科学   3522篇
妇产科学   2534篇
基础医学   15631篇
口腔科学   3966篇
临床医学   9826篇
内科学   24483篇
皮肤病学   2758篇
神经病学   10597篇
特种医学   2522篇
外国民族医学   1篇
外科学   9756篇
综合类   399篇
一般理论   48篇
预防医学   10846篇
眼科学   1770篇
药学   7585篇
中国医学   429篇
肿瘤学   7705篇
  2024年   120篇
  2023年   1039篇
  2022年   2237篇
  2021年   3692篇
  2020年   2313篇
  2019年   3110篇
  2018年   3541篇
  2017年   2705篇
  2016年   3145篇
  2015年   3463篇
  2014年   4566篇
  2013年   5941篇
  2012年   9038篇
  2011年   9405篇
  2010年   5130篇
  2009年   4314篇
  2008年   7468篇
  2007年   7469篇
  2006年   6869篇
  2005年   6414篇
  2004年   5758篇
  2003年   5131篇
  2002年   4622篇
  2001年   612篇
  2000年   429篇
  1999年   634篇
  1998年   799篇
  1997年   660篇
  1996年   563篇
  1995年   458篇
  1994年   434篇
  1993年   353篇
  1992年   322篇
  1991年   220篇
  1990年   209篇
  1989年   188篇
  1988年   180篇
  1987年   151篇
  1986年   173篇
  1985年   122篇
  1984年   142篇
  1983年   132篇
  1982年   165篇
  1981年   116篇
  1980年   130篇
  1979年   84篇
  1978年   88篇
  1977年   74篇
  1976年   63篇
  1974年   55篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

OBJECTIVE:

to estimate survival, mortality and cause of death among users or not of hydroxyurea with sickle cell disease.

METHOD:

cohort study with retrospective data collection, from 1980 to 2010 of patients receiving inpatient treatment in two Brazilian public hospitals. The survival probability was determined using the Kaplan-Meier estimator, survival calculations (SPSS version 10.0), comparison between survival curves, using the log rank method. The level of significance was p=0.05.

RESULTS:

of 63 patients, 87% had sickle cell anemia, with 39 using hydroxyurea, with a mean time of use of the drug of 20.0±10.0 years and a mean dose of 17.37±5.4 to 20.94±7.2 mg/kg/day, raising the fetal hemoglobin. In the comparison between those using hydroxyurea and those not, the survival curve was greater among the users (p=0.014). A total of 10 deaths occurred, with a mean age of 28.1 years old, and with Acute Respiratory Failure as the main cause.

CONCLUSION:

the survival curve is greater among the users of hydroxyurea. The results indicate the importance of the nurse incorporating therapeutic advances of hydroxyurea in her care actions.  相似文献   
992.
Objectives. We investigated whether eventual causes of death among a cohort of inmates imprisoned in the southeastern United States differed from those in previous prisoner studies.Methods. We matched 23 510 prisoners in Georgia, a state with historically low levels of heroin consumption but moderate amounts of injection drug use, who were incarcerated on June 30, 1991, to death registries through 2010. Main exposure was 4-year time intervals over 2 decades of observation; main outcome was mortality from liver disease, HIV, and overdose.Results. Although the HIV-related mortality rate exceeded that from liver-related conditions before 2003, liver disease subsequently surpassed HIV as a cause of death. Among 3863 deaths, 22 (0.6%) occurred within 2 weeks after release from prison. Of these, only 2 were caused by accidental poisoning (likely drug overdose). Cardiovascular disease and cancer were the most frequent causes of death in this aging cohort.Conclusions. Our study design deemphasized immediate deaths but highlighted long-term sequelae of exposure to viral hepatitis and alcohol. Treating hepatitis C and implementing interventions to manage alcohol use disorders may improve survival among prisoners in the Southeast.Drug use, incarceration, and mortality are intertwined: the use of illicit drugs can result in both incarceration and premature death. A 2010 international meta-analysis of prisoners'' survival after their release into the community emphasized mortality from overdose in the 2 weeks following discharge, possibly attributable to loss of opiate tolerance after forced sobriety in prison,1 but a more recent publication illustrates how this pattern may vary among subpopulations.2Long-term consequences of injection drug use include hepatitis C and HIV infection. In the United States, sexual exposure is the most common mode of HIV transmission, but the hepatitis C epidemic is mainly driven by the injection of drugs, even if the drug use is not sustained.3 HIV prevalence is 3 times as common among prisoners as among the general population,4 but hepatitis C prevalence is 13 times as high.5,6 Sequelae that could lead to death from hepatitis C typically occur 2 to 4 decades after injection drug use was initiated. Little is known about the long-term survival of inmates, particularly in the southeastern United States, where historical and recent patterns of drug use may differ from those in other regions.In contrast with other studies that have examined cohorts of released inmates, we sought to assess long-term prisoner survival by retrospectively following a cohort composed of a cross section of all imprisoned persons in the state of Georgia on a single day in 1991. In a previous study, we did not observe significantly higher mortality among members of this cohort immediately after release from prison than in the subsequent postrelease period.7 Multiple sources suggest that heroin use is less common in Georgia than in other states. Between 2002 and 2012, consistently fewer than 6.5% of men jailed in Atlanta, the capital of and largest city in Georgia, had evidence of heroin in their urine samples.8,9 The prevalence of opiate use in Atlanta was among the lowest for any city studied in the past decade by the Office of the National Drug Control Policy.8–10 In particular, heroin use was lower than in Washington State, site of a previous study of former inmate mortality.11 According to the Treatment Episode Data Set–Admissions for 1992 to 2010 from the Substance Abuse and Mental Health Services Administration, heroin addiction accounted for only 1.6% of admissions for drug rehabilitation in Georgia, but 9.7% in Washington State and 14.2% nationally.12In assessment of risk for hepatitis C, needle use—whether for heroin, cocaine, or another drug—is more important than what is injected. Needle use in Georgia is not uncommon. According to population-wide National Survey on Drug Use and Health data for 2002 to 2009, 1.1% of Georgians have ever used a needle to inject drugs, including cocaine—a moderate rate compared with the frequency in Washington State, where lifetime prevalence is 2.7%, and nationally, where prevalence is 1.6%.13 State-level data on needle use prior to 2002 are not publically available from the Substance Abuse and Mental Health Services Administration.The prevalence of hepatitis C in the Georgia general population is moderately high, especially in Atlanta. At Grady Memorial Hospital, the safety net charity hospital for Atlanta, the prevalence of hepatitis C among ambulatory primary care patients is 7%. A liver clinic established at this hospital saw 807 unique patients in its first 5 years of existence and was still receiving 60 new patient referrals each month through 2010.14 Three quarters of the patients were African American, and most patients were born between 1945 and 1965; 64% were former drug users, and only 4% were currently using.14 High prevalence of hepatitis C in this baby boomer birth cohort probably reflects time-limited parenteral drug use decades ago, perhaps as early as the Vietnam war era.15 Despite relatively low levels of heroin use in the state, we hypothesized that the prevalence of hepatitis C would be high among inmates in the Georgia prison system who were born between 1945 and 1965.We sought to describe the leading causes of death over 2 decades in a large cohort of all Georgians who were in state prisons on June 30, 1991, and to evaluate whether the immediate mortality following prison discharge was low, because Georgia is a state with low heroin use. In light of the moderate background rates of injection drug use in Georgia, we hypothesized that mortality from liver-related causes would rise over time as the cohort aged. Our first aim was to rank the causes of death and categorize which deaths occurred in prison, immediately after release, and subsequently. Second, we compared deaths from liver disease to those from HIV in 4-year intervals between 1991 and 2010.  相似文献   
993.

AIM:

qualitative study, which aimed to identify the barriers that influence nursing care practices related to the sexuality of women with gynecological and breast cancer.

METHODS:

the study was conducted with 16 professionals of the nursing area (nurses, nursing technicians and nursing assistants) from two sectors of a university hospital situated in the state of São Paulo, Brazil. The data was collected using semi-structured, in-depth individual interviews. All the interviews were recorded and the participants'' responses were identified and categorized using Content Analysis.

RESULTS:

three major themes were identified. These are as follows: 1) barriers related to the biomedical model; 2) barriers related to institutional dynamics and 3) barriers related to the social interpretations of sexuality.

CONCLUSIONS:

the results of this study showed that the systematized inclusion of this issue in nursing care routines requires changes in the health paradigm and in the work dynamic, as well as reflection on the personal values and social interpretations related to the topic. A major challenge is to divest sexuality of the taboos and prejudices which accompany it, as well as to contribute to the nursing team being more aware of the difficulties faced by women with gynaecological and breast cancer.  相似文献   
994.

OBJECTIVE:

to analyse the Redness, Oedema, Ecchymosis, Discharge, Approximation (REEDA) scale reliability when evaluating perineal healing after a normal delivery with a right mediolateral episiotomy.

METHOD:

observational study based on data from a clinical trial conducted with 54 randomly selected women, who had their perineal healing assessed at four time points, from 6 hours to 10 days after delivery, by nurses trained in the use of this scale. The kappa coefficient was used in the reliability analysis of the REEDA scale.

RESULTS:

the results indicate good agreement in the evaluation of the discharge item (0.75< Kappa ≥0.88), marginal and good agreement in the first three assessments of oedema (0.16< Kappa ≥0.46), marginal agreement in the evaluation of ecchymosis (0.25< Kappa ≥0.42) and good agreement regarding redness (0.46< Kappa ≥0.66). For the item coaptation, the agreement decreased from excellent in the first assessment to good in the last assessment. In the fourth evaluation, the assessment of all items displayed excellent or good agreement among the evaluators.

CONCLUSION:

the difference in the scores among the evaluators when applying the scale indicates that this tool must be improved to allow an accurate assessment of the episiotomy healing process.  相似文献   
995.
New high throughput technologies are now enabling simultaneous epigenetic profiling of DNA methylation at hundreds of thousands of CpGs across the genome. A problem of considerable practical interest is identification of large scale, global changes in methylation that are associated with environmental variables, clinical outcomes, or other experimental conditions. However, there has been little statistical research on methods for global methylation analysis using technologies with individual CpG resolution. To address this critical gap in the literature, we develop a new strategy for global analysis of methylation profiles using a functional regression approach wherein we approximate either the density or the cumulative distribution function (CDF) of the methylation values for each individual using B‐spline basis functions. The spline coefficients for each individual are allowed to summarize the individual's overall methylation profile. We then test for association between the overall distribution and a continuous or dichotomous outcome variable using a variance component score test that naturally accommodates the correlation between spline coefficients. Simulations indicate that our proposed approach has desirable power while protecting type I error. The method was applied to detect methylation differences, both genome wide and at LINE1 elements, between the blood samples from rheumatoid arthritis patients and healthy controls and to detect the epigenetic changes of human hepatocarcinogenesis in the context of alcohol abuse and hepatitis C virus infection. A free implementation of our methods in the R language is available in the Global Analysis of Methylation Profiles (GAMP) package at http://research.fhcrc.org/wu/en.html .  相似文献   
996.
997.
998.
999.

Objective

To examine associations between antidepressant use and health care utilization in young adults beginning maintenance hemodialysis (HD) therapy.

Patients and Methods

Antidepressant use, hospitalizations, and emergency department (ED) visits were examined in young adults (N=130; age, 18-44 years) initiating HD (from January 1, 2001, through December 31, 2013) at a midwestern US institution. Primary outcomes included hospitalizations and ED visits during the first year.

Results

Depression diagnosis was common (47; 36.2%) at HD initiation, yet only 28 patients (21.5%) in the cohort were receiving antidepressant therapy. The antidepressant use group was more likely to have diabetes mellitus (18 [64.3%] vs 33 [32.4%]), coronary artery disease (8 [28.6%] vs 12 [11.8%]), and heart failure (9 [32.1%] vs 15 [14.7%]) (P<.05 for all) than the untreated group. Overall, 68 (52.3%) had 1 or more hospitalizations and 33 (25.4%) had 1 or more ED visits in the first year. The risk of hospitalization during the first year was higher in the antidepressant use group (hazard ratio, 2.35; 95% CI, 1.39-3.96; P=.001), which persisted after adjustment for diabetes, coronary artery disease, and heart failure (hazard ratio, 1.94; 95% CI, 1.22-3.10; P=.006). Emergency department visit rates were similar between the groups.

Conclusion

Depression and antidepressant use for mood indication are common in young adult incident patients initiating HD and and are associated with higher hospitalization rates during the first year. Further research should determine whether antidepressants are a marker for other comorbidities or whether treated depression affects the increased health care use in these individuals.  相似文献   
1000.
Objectives: There is evidence that increasing severity of hypertriglyceridemia increases the risk of acute pancreatitis. There is a debate about superiority of treatment methods and previous works have specifically called for direct comparison between IV insulin and apheresis techniques. Identify patient characteristics predictive of lipid-lowering therapy selection in a large community hospital for treatment of hypertriglyceridemia; evaluate for a concentration-dependent relationship between hypertriglyceridemia severity and risk of acute pancreatitis; assess for differences in clinical outcomes between patients treated with IV insulin versus apheresis.

Methods: Single center, retrospective cohort study including patients with hypertriglyceridemia between January 2007 and December 2016. Main measures included frequency of pancreatitis, choice of lipid-lowering therapy, and clinical comparisons of diet, oral lipid-lowering agents, IV insulin, and apheresis.

Results: Initial serum triglyceride level and disease acuity was higher among patients in insulin and apheresis groups. Neither triglyceride level, Charlson comorbidity index, age, BISAP score, nor initial CRP predicted use of IV insulin versus apheresis. Prevalence of pancreatitis increased with higher triglyceride level, reaching 48% with triglycerides >2000 md/dL (p < 0.001). There was a significant decrease in serum triglycerides at each time interval (p < 0.05) in patients treated with IV insulin and apheresis, but no difference in clearance rate between the two. Length of stay did not differ between IV insulin and apheresis.

Conclusion: The presence of pancreatitis, hyperglycemia, and hypertriglyceridemia severity influenced selection of therapies like IV insulin and apheresis. We found no superiority of either IV insulin or apheresis in the treatment of severe hypertriglyceridemia among patients hospitalized for pancreatitis.  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