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   5784篇
  免费   422篇
  国内免费   23篇
耳鼻咽喉   46篇
儿科学   239篇
妇产科学   136篇
基础医学   920篇
口腔科学   53篇
临床医学   621篇
内科学   1129篇
皮肤病学   62篇
神经病学   683篇
特种医学   140篇
外科学   592篇
综合类   38篇
预防医学   627篇
眼科学   52篇
药学   465篇
中国医学   26篇
肿瘤学   400篇
  2024年   5篇
  2023年   34篇
  2022年   59篇
  2021年   162篇
  2020年   96篇
  2019年   149篇
  2018年   164篇
  2017年   124篇
  2016年   140篇
  2015年   171篇
  2014年   194篇
  2013年   298篇
  2012年   408篇
  2011年   481篇
  2010年   253篇
  2009年   234篇
  2008年   398篇
  2007年   409篇
  2006年   383篇
  2005年   378篇
  2004年   374篇
  2003年   338篇
  2002年   318篇
  2001年   38篇
  2000年   24篇
  1999年   42篇
  1998年   64篇
  1997年   59篇
  1996年   57篇
  1995年   40篇
  1994年   37篇
  1993年   33篇
  1992年   20篇
  1991年   17篇
  1990年   17篇
  1989年   15篇
  1988年   15篇
  1987年   16篇
  1986年   10篇
  1985年   11篇
  1984年   22篇
  1983年   13篇
  1982年   17篇
  1981年   14篇
  1980年   22篇
  1979年   12篇
  1978年   13篇
  1977年   5篇
  1973年   5篇
  1972年   4篇
排序方式: 共有6229条查询结果,搜索用时 31 毫秒
991.
ObjectiveHow biochemical variables influence the costs of the Brazilian National Healthcare System, according to body composition and physical activity.MethodsParticipated in this study 168 patients. Biochemical variables were glucose, triglycerides, total cholesterol, high, low, very low density lipoprotein and C-reactive protein (CRP). For the cost analysis the medical records was analyzed. Physical activity was assessed through questionnaire. Body adiposity was assessed by body mass index. Four groups were defined according body adiposity and physical activity.ResultsThe active obese group had higher values of very low density lipoprotein and triglycerides when compared to the inactive obese. The non-obese inactive group had lower values of non-high density lipoprotein compared to the inactive obese. The non-obese active group presented lower insulin value when compared to the inactive obese. The inactive obese group presented higher values in the CRP when compared to the non-obese active and inactive groups when compared to non-obese and active obese group. There was a positive correlation between insulin, glucose, CRP and drug and total costs.ConclusionsBiochemical variables were different according to body composition and physical activity. Insulin, glucose and CRP were related to cost in drugs and total costs.  相似文献   
992.
The present study sought to identify Escherichia coli sources in a small catchment and to use the agro-hydrological model soil and water assessment tool (SWAT) to estimate their impact on river water quality. The innovative aspects of this research are to assess the hourly variations of fecal contamination and to take these variations into account in the model to provide a better evaluation of river quality. Thus, water samples were taken weekly at the river outlet (n = 4) and 24-h monitoring sessions were performed during low and high-flow periods (n = 74). E. coli variations were found to be primarily linked to rainfall and not to resuspension mechanisms. Subdaily fluctuations and deviations were ±0.33 log10 cfu/100 mL and ±0.70 log10 cfu/100 mL for dry (<3 mm/day) and wet (>3 mm/day) weather, respectively. After river flow calibration, all known pollution sources (septic systems, manure spreading, farm discharges) were introduced into SWAT. The model reproduced the fecal contamination in the river and the use of subdaily deviations allowed us to evaluate the simulation quality and compare grab samplings with simulated daily E. coli concentration, thus confirming that the performance of the model is better when additional information on hourly concentration variations is used.  相似文献   
993.
Cancer is the second leading cause of death in the US and in Mississippi. Breast cancer (BC) is the most common cancer among women, and the underlying pathophysiology remains unknown, especially among African American (AA) women. The study purpose was to examine the joint effect of menopause status (MS) and hormone replacement therapy (HRT) on the association with cancers, particularly BC using data from the Jackson Heart Study. The analytic sample consisted of 3202 women between 35 and 84 years of which 73.7% and 22.6% were postmenopausal and on HRT, respectively. There were a total of 190 prevalent cancer cases (5.9%) in the sample with 22.6% breast cancer cases. Menopause (p<0.0001), but not HRT (p=0.6402), was independently associated with cancer. Similar results were obtained for BC. BC, cancer, hypertension, type 2 diabetes, prevalent cardiovascular disease, physical activity and certain dietary practices were all significantly associated with the joint effect of menopause and HRT in the unadjusted analyses. The family history of cancer was the only covariate that was significantly associated with cancer in the age-adjusted models. In examining the association of cancer and the joint effect of menopause and HRT, AA women who were menopausal and were not on HRT had a 1.97 (95% CI: 1.15, 3.38) times odds of having cancer compared to pre-menopausal women after adjusting for age; which was attenuated after further adjusting for family history of cancer. Given that the cancer and BC cases were small and key significant associations were attenuated after adjusting for the above mentioned covariates, these findings warrant further investigation in studies with larger sample sizes of cancer (and BC) cases.  相似文献   
994.
995.
This article discusses the background and process for developing a multi-year corporate quality plan. The Ottawa Hospital's goal is to be a top 10% performer in quality and patient safety in North America. In order to create long-term measurable and sustainable changes in the quality of patient care, The Ottawa Hospital embarked on the development of a three-year strategic corporate quality plan. This was accomplished by engaging the organization at all levels and defining quality frameworks, aligning with internal and external expectations, prioritizing strategic goals, articulating performance measurements and reporting to stakeholders while maintaining a transparent communication process. The plan was developed through an iterative process that engaged a broad base of health professionals, physicians, support staff, administration and senior management. A literature review of quality frameworks was undertaken, a Quality Plan Working Group was established, 25 key stakeholder interviews were conducted and 48 clinical and support staff consultations were held. The intent was to gather information on current quality initiatives and challenges encountered and to prioritize corporate goals and then create the quality plan. Goals were created and then prioritized through an affinity exercise. Action plans were developed for each goal and included objectives, tasks and activities, performance measures (structure, process and outcome), accountabilities and timelines. This collaborative methodology resulted in the development of a three-year quality plan. Six corporate goals were outlined by the tenets of the quality framework for The Ottawa Hospital: access to care, appropriate care (effective and efficient), safe care and satisfaction with care. Each of the six corporate goals identified objectives and supporting action plans with accountabilities outlining what would be accomplished in years one, two and three. The three-year quality plan was approved by senior management and the board in April 2009. This process has supported The Ottawa Hospital's journey of excellence through the creation of a quality plan that will enable long-term measurable and sustainable changes in the quality of patient care. It also engaged healthcare providers who aim to achieve more measured quality patient care, engaged practitioners through collaboration resulting in both alignment of goals and outcomes and allowed for greater commitment by those responsible for achieving quality goals.  相似文献   
996.
We investigated time trends in maternal weight before and during pregnancy and in infant birthweight in France, from 1972 to 2003, using data on singleton live term births from the representative National Perinatal Surveys of 1972, 1981, 1995, 1998 and 2003 (n=8,664, 4,494, 11,445, 12,006, 12,692, respectively). Mothers were interviewed a few days after delivery and data on delivery and the newborn were extracted from hospital records. Maternal prepregnancy weight, height, body mass index and pregnancy weight gain all increased from 1972 to 2003; however, birthweight did not show a parallel trend. After taking gestational age, maternal age, parity, country of origin, newborn gender and maternal smoking during pregnancy into account, mean birthweight increased between 1972 and 1995 but decreased thereafter and, consistently, there was an increase in small-for-gestational age (SGA) and a decrease in large-for-gestational age newborns. Further adjustment for induced delivery, an indicator of obstetric practice, did not change the results. A similar variation has been observed very recently in the US and in Germany. Further research is needed to identify the factors responsible for these discordant changes and especially the factors responsible for the recent increase in SGA since this has been shown to be associated with poorer health in later life.  相似文献   
997.
Based on the idea that electric light at night might account for a portion of the high and rising risk of breast cancer worldwide, it was predicted long ago that women working a non-day shift would be at higher risk compared with day-working women. This hypothesis has been extended more recently to prostate cancer. On the basis of limited human evidence and sufficient evidence in experimental animals, in 2007 the International Agency for Research on Cancer (IARC) classified 'shift work that involves circadian disruption' as a probable human carcinogen, group 2A. A limitation of the epidemiological studies carried out to date is in the definition of 'shift work.' IARC convened a workshop in April 2009 to consider how 'shift work' should be assessed and what domains of occupational history need to be quantified for more valid studies of shift work and cancer in the future. The working group identified several major domains of non-day shifts and shift schedules that should be captured in future studies: (1) shift system (start time of shift, number of hours per day, rotating or permanent, speed and direction of a rotating system, regular or irregular); (2) years on a particular non-day shift schedule (and cumulative exposure to the shift system over the subject's working life); and (3) shift intensity (time off between successive work days on the shift schedule). The group also recognised that for further domains to be identified, more research needs to be conducted on the impact of various shift schedules and routines on physiological and circadian rhythms of workers in real-world environments.  相似文献   
998.

Introduction

The use of risk calculators predicting clinically significant prostate cancer (csCaP) on biopsy reduces unnecessary biopsies and overdiagnosis of indolent disease compared to a Prostate Specific Antigen (PSA) strategy. Updating these tools using more specific outcome measures and contemporary predictors could potentially lead to further reductions. Our objective was to assess clinical impact of the 4 kallikrein (4K) score, the Rotterdam Prostate Cancer Risk Calculator (RPCRC), and the combination of both for predicting csCaP based on the latest International Society of Urological Pathology grading system and cribriform growth pattern.

Materials and methods

Our prospective cohort consisted of 2,872 men from the first screening round in the European Randomized Study of Screening for Prostate Cancer Rotterdam; biopsy indication PSA ≥ 3.0. The predictive performance of the 4Kscore, RPCRC, and the combination of RPCRC with 4Kscore were assessed with area under the receiver operator characteristic curve (AUC) and calibration plots. Decision curve analysis was used to evaluate the reduction of unnecessary biopsy and indolent CaP.

Results

The csCaP was present in 242 (8%) men, and indolent CaP in 578 (20%). The 4Kscore and RPCRC had similar high AUCs (0.88 vs. 0.87; P?=?0.41). The 4Kscore-RPCRC combination improved AUC to 0.89 compared to 4Kscore (P < 0.01) and RPCRC (P < 0.01). The RPCRC and 4Kscore reduced the number of Bx with 42 and 44, respectively, per 100 men at risk compared to a ≥PSA 3.0 strategy without increasing missed csCaP. The RPCRC-4Kscore combination resulted in a slight additional net reduction of 3.3 biopsies per 100 men.

Conclusions

The RPCRC and 4Kscore had similar reductions of unnecessary biopsies and overdiagnosis of indolent disease. Combination of both models slightly reduced unnecessary biopsies further. Gain in net benefit must, however, be weighed against additional costs and availability of tests.  相似文献   
999.
1000.
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