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   2147篇
  免费   108篇
  国内免费   34篇
耳鼻咽喉   9篇
儿科学   36篇
妇产科学   32篇
基础医学   212篇
口腔科学   36篇
临床医学   191篇
内科学   325篇
皮肤病学   16篇
神经病学   80篇
特种医学   42篇
外科学   267篇
综合类   324篇
预防医学   250篇
眼科学   16篇
药学   228篇
中国医学   64篇
肿瘤学   161篇
  2023年   36篇
  2022年   70篇
  2021年   98篇
  2020年   86篇
  2019年   76篇
  2018年   96篇
  2017年   61篇
  2016年   70篇
  2015年   62篇
  2014年   173篇
  2013年   132篇
  2012年   123篇
  2011年   128篇
  2010年   101篇
  2009年   108篇
  2008年   94篇
  2007年   99篇
  2006年   83篇
  2005年   73篇
  2004年   52篇
  2003年   50篇
  2002年   35篇
  2001年   33篇
  2000年   46篇
  1999年   22篇
  1998年   17篇
  1997年   23篇
  1996年   29篇
  1995年   31篇
  1994年   19篇
  1993年   14篇
  1992年   9篇
  1991年   10篇
  1990年   9篇
  1989年   5篇
  1988年   5篇
  1987年   4篇
  1986年   6篇
  1985年   14篇
  1984年   5篇
  1983年   11篇
  1982年   9篇
  1981年   16篇
  1979年   9篇
  1978年   3篇
  1977年   4篇
  1976年   10篇
  1975年   3篇
  1974年   5篇
  1973年   4篇
排序方式: 共有2289条查询结果,搜索用时 31 毫秒
41.
《Vaccine》2021,39(51):7387-7393
BackgroundIn 2015, the German Standing Committee on Vaccination (STIKO) changed the pneumococcal conjugate vaccination (PCV) schedule for mature infants from a 3+1 scheme (2, 3, 4, and 11–14 months of age) to a 2+1 scheme (2, 4, and 11–14 months of age). For premature infants, the 3+1 scheme remained. The aim of this study was to assess vaccination rates, completeness, and timeliness for PCV in premature infants before and after the modified recommendation.MethodsA retrospective claims data analysis using the “Institut für angewandte Gesundheitsforschung Berlin” Research Database was conducted. Premature infants born in 2013 and 2016 with an individual follow-up of 24 months were included. Hexavalent combination (HEXA) vaccination with a consistent 3+1 recommendation for mature and premature infants was analyzed as reference vaccination.ResultsAfter 24 months, the PCV rate for at least one dose remained stable in premature newborns of 2016 compared to 2013, while the HEXA vaccination rate increased slightly. However, a significant decrease of a completed PCV schedule (4 doses) in premature infants was noted, whereas the completeness of HEXA vaccination did not change. The timeliness of PCV in premature newborns increased for the first and the booster PCV, while the timeliness of HEXA immunization did not change from 2013 to 2016.ConclusionAlthough STIKO still recommends a 3+1 PCV schedule for premature infants in Germany, premature infants were vaccinated according to the changed recommendations for mature born infants. A substantial share of premature infants remained unvaccinated, and their vaccinations were often delayed.  相似文献   
42.
In this paper, we propose a graphcut method to segment the cardiac right ventricle (RV) and left ventricle (LV) by using context information from each other. Contextual information is very helpful in medical image segmentation because the relative arrangement of different organs is the same. In addition to the conventional log-likelihood penalty, we also include a “context penalty” that captures the geometric relationship between the RV and LV. Contextual information for the RV is obtained by learning its geometrical relationship with respect to the LV. Similarly, RV provides geometrical context information for LV segmentation. The smoothness cost is formulated as a function of the learned context which helps in accurate labeling of pixels. Experimental results on real patient datasets from the STACOM database show the efficacy of our method in accurately segmenting the LV and RV. We also conduct experiments on simulated datasets to investigate our method’s robustness to noise and inaccurate segmentations.  相似文献   
43.
This quasi-experimental research aimed to study the effect of health behavior modification program in relation toknowledge, self-efficacy, expectation, and practice for liver fluke prevention among the risk group from Bueng Samrongsub-district, Kaeng Sanam Nang district, Nakhon Ratchasima province, Northeast Thailand. The total of 66 participantswas assigned to experimental and comparison group, 33 participants in each group, 12-weeks intervene period. Theexperimental group was received health behavioral modification programs based on health education, self-efficacy,motivation, social support and networking. Pre-and-post-tests were measured using predesigned questionnaires. Thecomparative analysis was analyzed by paired sample t-test and independent sample t-test at the 0.05 level of significance.The results revealed that the experimental group had significantly greater knowledge, self-efficacy, expectation, andpractice for liver fluke prevention than those in the comparison group (p < 0.05). In conclusion, this was a successfulhealth education program for liver fluke avoidance. Participants were gained the correct knowledge and had the higherself-efficacy, expectation, and practice regrading liver fluke prevention. Therefore, it may useful for further behaviormodification in the other epidemic areas.  相似文献   
44.
This paper is a summary of Anna Freud's important contribution to our understanding of child development and its deviations. It highlights her concern for the whole child, both his internal and external world and their mutual interactions. An example is given of changes in the law with regard to children in which her views were influential. Vignettes are given showing the evolution of her thinking regarding treatment techniques in the light of the widening range of developmental disturbances and presenting problems.  相似文献   
45.
The phenomenon of binaural summation in which the addition of signals presented to the two ears simultaneously takes place at a central level, has been known for many years. It is reasonable to assume that the pattern of summation differs between subjects with central lesions and those with lesions in the peripheral auditory tracts. Various tests have been proposed to aid in locating the site of the lesion which compare the monaural and binaural speech discrimination scores

In the present work, two of these tests have been examined. Thee group of subjects have been used: (1) a normally hearing group; (2) a group with hearing impairment resulting from cochlea pathology, and (3) a group with hearing impairment resulting from lesions at the level of the cochlear nuclei. The results showed that neither test differentiate between peripheral and cochlear nuclei lesions  相似文献   
46.

Introduction

The American Joint Committee on Cancer (AJCC) tumor, node, metastasis classification system (TNM) staging manual has been updated and provides more specified stage grouping for prostate cancer (PCa). We aimed to validate the updated AJCC stage groups for PCa using a radical prostatectomy (RP) cohort.

Patients and Methods

We analyzed the data of 3032 patients previously treated with RP for localized PCa. We stratified patients into stage groups according to the 8th edition of the AJCC manual and compared biochemical recurrence (BCR)-free survival using Kaplan-Meier analyses.

Results

There were 217 patients in stage group I, 33 in IIA, 1101 in IIB, 535 in IIC, 129 in IIIA, 781 in IIIB, and 236 in IIIC. There were no significant differences in BCR-free survival between stage groups IIC and IIIA (P = .875). Subsequently, the low–Gleason score (GS) IIIA subgroup (GS ≤ 3 + 4, P = .025) showed superior BCR-free survival than the IIC group, and the high-GS IIIA subgroups (GS ≥ 4 + 3, P = .004) showed a poorer BCR-free survival than the IIC group. Furthermore, there were no significant differences between groups I and IIA (P = 330) and between groups IIA and IIB (P = .942). Our new staging system provided a better ability to discriminate the prognosis of each group. However, our study has several limitations, such as retrospective design, relatively short follow-up period, and need for further validation.

Conclusion

The current AJCC prognostic groups show some contradictory results, particularly concerning prognosis of the IIC and IIIA groups. We suggest that GS be given more weight than serum prostate-specific antigen level in stage group stratification.  相似文献   
47.
《Urologic oncology》2015,33(3):109.e7-109.e13
BackgroundRobotic-assisted laparoscopic radical prostatectomy is a current standard treatment for localized prostate cancer, with treatment failure defined by biochemical recurrence (BCR). Open radical prostatectomy series have identified the presence of a positive surgical margin (PSM) as a predictor of long-term recurrence, a measure that is affected by the surgeon׳s skill. We evaluate the effect of PSM parameters on BCR rates from robotic-assisted laparoscopic radical prostatectomy, across 3 high-volume institutions.MethodsDe-identifiable clinicopathological and histopathological data were prospectively collected for 4,001 patients with at least 3 years of follow-up. Kaplan-Meier plots and 3 statistical models were used to evaluate the effect of margin parameters on BCR, via crude rates, traditional multivariable Cox regression, and a propensity-adjusted Cox regression model.ResultsOverall, 37% of men with a PSM developed BCR compared with 10% of men with negative margins (hazard ratio [HR] = 1.81, 95% CI: 1.47–2.22). Length ≥3 mm or a multifocal positive margin was associated with a higher risk of BCR compared with negative margin cases. On multivariable Cox regression analysis of the positive margin cohort, only apical margins significantly predicted BCR relative to basal margins (HR = 2.03, 95% CI: 1.01–4.09), whereas there was no significant difference in BCR rates for posterolateral margins relative to basal margins (HR = 1.62, 95% CI: 0.84–3.11). Propensity-adjusted modeling confirmed a greater effect of apical compared with posterolateral PSM.ConclusionsA PSM length ≥3 mm is predictive of BCR, as is to a lesser extent multiple positive margins. In contrast to open prostatectomy series, posterolateral margins carry a smaller risk of BCR compared with apical margins.  相似文献   
48.
ObjectiveTo assess serum vitamin D status and its relations to other biochemical parameters in type 2 diabetic patients from Gaza Strip.Materials and methodsThis case-control study included 58 type 2 diabetic patients as well as 58 non-diabetic controls. Patients and controls were matched for age and gender. Data were obtained from questionnaire interview, and biochemical analysis of blood samples.ResultsSerum vitamin D was significantly lower in diabetic patients compared to non-diabetic controls (25.9 ± 11.0 versus 34.6 ± 13.8 ng/dl, % difference = 28.8%, P < 0.001). The number of patients having vitamin D deficient, insufficient and sufficient were 6 (10.4%), 35 (60.3%) and 17 (29.3%) compared to controls of 3 (5.2%), 16 (27.6%) and 39 (67.2%), respectively (χ2 = 14.672, P < 0.001). Serum glucose, glycated hemoglobin (HbA1c), serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and triglycerides were significantly higher in patients than in controls whereas serum insulin, high density lipoprotein cholesterol (HDL-C) and calcium were significantly lower in patients. Serum vitamin D showed significant negative correlations with HbA1c (r = ? 0.186, P = 0.046), ALT (r = ? 192, P = 0.040) and AST (r = ? 0.188, P = 0.044) whereas significant positive correlations were found with HDL-C (r = 0.188, P = 0.044) and calcium (r = 0.239, P = 0.010).ConclusionThe significant negative and positive correlations of vitamin D with HbA1c and calcium, respectively suggests that vitamin D supplementation would be of potential therapeutic value in clinical settings for controlling of type 2 diabetes and more importantly its complications. However, a well-designed clinical trials are needed to define the contribution of vitamin D status and therapy in the global diabetes problem.  相似文献   
49.
Titanium dioxide nanoparticles (NpTiO2) are the most widely-used nanoparticle type and the adsorption of metals such as lead (PbII) onto their surface is a major source of concern to scientists. This study evaluated the effects of the associated exposure to both types of contaminant, i.e., lead (a known genotoxic metal) and NpTiO2, in a freshwater fish (Astyanax serratus) through intraperitoneal injection for an acute assay of 96 h. The effects of this exposure were evaluated using the comet assay, DNA diffusion assay and piscine micronucleus test, as well as the quantification of antioxidant enzymes (SOD, CAT, and GST) and metallothioneins. Our findings indicate that co-exposure of PbII with NpTiO2 can provoke ROS imbalances, leading to DNA damage in the blood and liver tissue of A. serratus, as well as modifying erythropoiesis in this species, inducing necrosis and changing the nuclear morphology of the erythrocytes.  相似文献   
50.
IntroductionThe aim of our study was to compare the detection rate of anti-3-18F-FACBC PET/CT in comparison with 11C-choline PET/CT in the evaluation of disease recurrence of PCa after radical prostatectomy.Patients and MethodsTwenty-eight consecutive patients with biochemical relapse after radical prostatectomy were submitted to anti-3-18F-FACBC PET/CT and 11C-choline PET/CT to evaluate the site of disease recurrence. Androgen deprivation therapy was avoided in all cases. The primary end point was the overall detection rate of the 2 radiotracers. A patient-based analysis and a lesion-based analysis was performed. The target to background ratio (TBR) of each lesion was reported.ResultsAt the time of PET scan, mean age was 67 years and mean prostate specific antigen (PSA) relapse was 2.9 ng/mL (range: 0.2-14.6). In patient-based analyses, 11C-choline PET/CT was positive in 5 patients and negative in 23 (detection rate = 17.8%) and anti-3-18F-FACBC PET/CT was positive in 10 patients and negative in 18 (detection rate = 35.7%). All lesions that were positive using 11C-choline were positive using anti-3-18F-FACBC PET/CT but with the latter radiotracer, 11 (61.1%) additional tumors were identified including 5 (17.8%) additional patients. The TBR of anti-3-18F-FACBC was greater than 11C-choline in 15 of 18 lesions, confirming a better image quality and contrast.ConclusionThis preliminary study demonstrated that the detection rate of anti-3-18F-FACBC PET/CT is greater in comparison with 11C-choline, with approximately 20% of additional patients and approximately 60% additional lesions detected. Further studies, however, are required to assess the exact added value of this new tracer.  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