全文获取类型
收费全文 | 2486篇 |
免费 | 267篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 41篇 |
妇产科学 | 90篇 |
基础医学 | 400篇 |
口腔科学 | 128篇 |
临床医学 | 268篇 |
内科学 | 403篇 |
皮肤病学 | 51篇 |
神经病学 | 218篇 |
特种医学 | 168篇 |
外科学 | 376篇 |
综合类 | 45篇 |
一般理论 | 6篇 |
预防医学 | 259篇 |
眼科学 | 38篇 |
药学 | 125篇 |
肿瘤学 | 131篇 |
出版年
2023年 | 14篇 |
2022年 | 15篇 |
2021年 | 36篇 |
2020年 | 21篇 |
2019年 | 43篇 |
2018年 | 46篇 |
2017年 | 45篇 |
2016年 | 38篇 |
2015年 | 45篇 |
2014年 | 51篇 |
2013年 | 76篇 |
2012年 | 102篇 |
2011年 | 110篇 |
2010年 | 78篇 |
2009年 | 62篇 |
2008年 | 105篇 |
2007年 | 105篇 |
2006年 | 89篇 |
2005年 | 100篇 |
2004年 | 86篇 |
2003年 | 79篇 |
2002年 | 75篇 |
2001年 | 72篇 |
2000年 | 71篇 |
1999年 | 65篇 |
1998年 | 36篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 22篇 |
1994年 | 27篇 |
1993年 | 27篇 |
1992年 | 86篇 |
1991年 | 62篇 |
1990年 | 71篇 |
1989年 | 66篇 |
1988年 | 53篇 |
1987年 | 54篇 |
1986年 | 44篇 |
1985年 | 59篇 |
1984年 | 52篇 |
1983年 | 31篇 |
1982年 | 25篇 |
1981年 | 21篇 |
1980年 | 20篇 |
1979年 | 35篇 |
1977年 | 14篇 |
1975年 | 18篇 |
1974年 | 14篇 |
1971年 | 20篇 |
1970年 | 14篇 |
排序方式: 共有2756条查询结果,搜索用时 15 毫秒
991.
CHERILYN G. SHEETS DDS YASUYUKI ONO DT †TADANORI TANIGUCHI DT † 《Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.]》1993,5(5):215-220
A method to provisionalize porcelain laminate veneers, similar to previously described methods for provi-sionalizing crowns, is presented. The advantages of this system include the ability to have a prototype restoration for evaluation of esthetics and phonetics, thermal protection, and protection from preparation fracture. Additional advantages include improved tissue health and ease of progressing from the provisionaliza-tion stage to the final bonding stage. 相似文献
992.
Graves PM Osgood DE Thomson MC Sereke K Araia A Zerom M Ceccato P Bell M Del Corral J Ghebreselassie S Brantly EP Ghebremeskel T 《Tropical medicine & international health : TM & IH》2008,13(2):218-228
Objective To assess the effectiveness of impregnated mosquito nets, indoor residual spraying and larval control relative to the impacts of climate variability in the decline of malaria cases in Eritrea.
Methods Monthly data on clinical malaria cases by subzoba (district) in three zoba s (zones) of Eritrea for 1998–2003 were used in Poisson regression models to determine whether there is statistical evidence for reduction in cases by DDT, malathion, impregnated nets and larval control used over the period, while analysing the effects of satellite-derived climate variables in the same geographic areas.
Results Both indoor residual spraying (with DDT or malathion) and impregnated nets were independently and significantly negatively associated with reduction in cases, as was larval control in one zoba . Malaria cases were significantly positively related to differences in current and previous months' vegetation (NDVI) anomalies. The relationship to rainfall differences 2 and 3 months previously was also significant, but the direction of the effect varied by zoba . Standardized regression coefficients indicated a greater effect of climate in the zoba with less intense malaria transmission.
Conclusion The results support the view that both indoor residual spraying and impregnated nets have been independently effective against malaria, and that larval control was also effective in one area. Thus climate, while significant, is not the only explanation for the recent decline in malaria cases in Eritrea. If appropriate statistical approaches are used, routine surveillance data from cases attending health facilities can be useful for assessing control programme success and providing estimates of the effectiveness of individual control measures. Effectiveness estimates suitable for use in cost-effectiveness analysis have been obtained. 相似文献
Methods Monthly data on clinical malaria cases by subzoba (district) in three zoba s (zones) of Eritrea for 1998–2003 were used in Poisson regression models to determine whether there is statistical evidence for reduction in cases by DDT, malathion, impregnated nets and larval control used over the period, while analysing the effects of satellite-derived climate variables in the same geographic areas.
Results Both indoor residual spraying (with DDT or malathion) and impregnated nets were independently and significantly negatively associated with reduction in cases, as was larval control in one zoba . Malaria cases were significantly positively related to differences in current and previous months' vegetation (NDVI) anomalies. The relationship to rainfall differences 2 and 3 months previously was also significant, but the direction of the effect varied by zoba . Standardized regression coefficients indicated a greater effect of climate in the zoba with less intense malaria transmission.
Conclusion The results support the view that both indoor residual spraying and impregnated nets have been independently effective against malaria, and that larval control was also effective in one area. Thus climate, while significant, is not the only explanation for the recent decline in malaria cases in Eritrea. If appropriate statistical approaches are used, routine surveillance data from cases attending health facilities can be useful for assessing control programme success and providing estimates of the effectiveness of individual control measures. Effectiveness estimates suitable for use in cost-effectiveness analysis have been obtained. 相似文献
993.
J. D. Beck J. A. Weintraub J. A. Disney R. C. Graves J. W. Stamm L. M. Kaste H. M. Bohannan 《Community dentistry and oral epidemiology》1992,20(6):313-321
The purpose of this analysis is to compare three different statistical models for predicting children likely to be at risk of developing dental caries over a 3-yr period. Data are based on 4117 children who participated in the University of North Carolina Caries Risk Assessment Study, a longitudinal study conducted in the Aiken, South Carolina, and Portland, Maine areas. The three models differed with respect to either the types of variables included or the definition of disease outcome. The two "Prediction" models included both risk factor variables thought to cause dental caries and indicator variables that are associated with dental caries, but are not thought to be causal for the disease. The "Etiologic" model included only etiologic factors as variables. A dichotomous outcome measure--none or any 3-yr increment, was used in the "Any Risk Etiologic model" and the "Any Risk Prediction Model". Another outcome, based on a gradient measure of disease, was used in the "High Risk Prediction Model". The variables that are significant in these models vary across grades and sites, but are more consistent among the Etiologic model than the Predictor models. However, among the three sets of models, the Any Risk Prediction Models have the highest sensitivity and positive predictive values, whereas the High Risk Prediction Models have the highest specificity and negative predictive values. Considerations in determining model preference are discussed. 相似文献
994.
Despite 40 years of research demonstrating the efficacy of antihypertensive medications for lowering blood pressure and decreasing cardiovascular disease, hypertension control rates worldwide remain low. We explored here how both medication efficacy rates and patient/physician decision-making (discontinuation rates) affect overall hypertension control rates. To do this we introduced the use of Kaplan-Meier methodology to predict hypertension control rates separately within age strata. An important aspect of our analysis is the use of a "treatment intensity score," including both the number of agent(s) and the percentage of maximal dose of agent(s). We investigated how blood pressure control rates vary with age, gender, and treatment intensity. Our analysis found that both efficacy and discontinuation rates at different treatment intensities vary with age and gender, so that for each increase in age by 1 decade, the log hazard of achieving controlled blood pressure at any given intensity decreases by 0.10 in men and 0.20 in women. Overall hypertension control rates ranged from 80.8% for persons age 15 to 39 years to only 42.1% for persons age >/=80 years. Our analysis more accurately represents achievable hypertension control rates, with differences by gender, than previous work, because we investigated the contributions of efficacy and treatment aggressiveness in the control of hypertension. 相似文献
995.
Viruses MT325 and FR483, members of the family Phycodnaviridae, genus Chlorovirus, infect the fresh water, unicellular, eukaryotic, chlorella-like green alga, Chlorella Pbi. The 314,335-bp genome of MT325 and the 321,240-bp genome of FR483 are the first viruses that infect Chlorella Pbi to have their genomes sequenced and annotated. Furthermore, these genomes are the two smallest chlorella virus genomes sequenced to date, MT325 has 331 putative protein-encoding and 10 tRNA-encoding genes and FR483 has 335 putative protein-encoding and 9 tRNA-encoding genes. The protein-encoding genes are almost evenly distributed on both strands, and intergenic space is minimal. Approximately 40% of the viral gene products resemble entries in public databases, including some that are the first of their kind to be detected in a virus. For example, these unique gene products include an aquaglyceroporin in MT325, a potassium ion transporter protein and an alkyl sulfatase in FR483, and a dTDP-glucose pyrophosphorylase in both viruses. Comparison of MT325 and FR483 protein-encoding genes with the prototype chlorella virus PBCV-1 indicates that approximately 82% of the genes are present in all three viruses. 相似文献
996.
Anthony Spirito Lynn Hernandez Mary Kathryn Cancilliere Hannah R. Graves Ana Maria Rodriguez Don Operario 《Journal of clinical child and adolescent psychology》2018,47(6):S467-S479
The purpose of this article is to present the results of a treatment development study designed to examine the feasibility, acceptability, and preliminary efficacy of motivational enhancement therapy (MET) for substance using, truant adolescents plus the Family Check-Up (FCU) for parents. A randomized controlled trial was used to test the hypothesis that MET plus the FCU (MET/FCU) would lead to greater reductions in alcohol and marijuana use as well as truant behavior compared to a psychoeducation (PE) condition delivered to both adolescents and parents. Participants (n = 69; M age = 15.8 years) were 39% female, 59% White, and 31% Hispanic/Latino. Adolescents were referred from family court, from school truancy courts, from school counselors, or after presentations in high school health classes. Eligible participants reported using marijuana at least 3 times in the prior 90 days and a history of school truancy in the prior school year. The MET/FCU condition was found to be feasible to implement and was acceptable to both adolescents and parents. The PE condition was also found to be an acceptable and credible comparison condition by participants. Results at the 6-month follow-up favored MET/FCU over PE on days of marijuana use and number of times marijuana was smoked per day (medium effect), high volume drinking days and other drug use (small to medium effects), truancy indicators (small effects), parental monitoring (medium to large effects), and parent–teen problem solving (medium to large effects). A larger study to test the ef?cacy of the MET/FCU appears warranted based on these promising findings. 相似文献
997.
998.
Colleen A. Weeks Jacquelyn D. Marsh Steven J. MacDonald Stephen Graves Edward M. Vasarhelyi 《The Journal of arthroplasty》2018,33(11):3412-3415
Background
This study estimates the cost-effectiveness of patellar resurfacing in total knee arthroplasty (TKA).Methods
We conducted a cost-effectiveness analysis using a decision analytic model representing a hypothetical TKA cohort, with or without patellar resurfacing, using data from the 2014 Australian Registry. The model represents 3 possible postoperative health states: (1) well, (2) patellofemoral pain, or (3) serious adverse event (any event resulting in a revision). Our effectiveness outcome was the quality-adjusted life year, from published utility scores. We estimated cost-effectiveness from a Canadian public healthcare payer perspective. Costs and quality of life were valued in 2015 United States dollars and discounted annually at 5%.Results
Our results suggest that TKA with resurfacing is cost-effective compared to nonresurfacing. Unresurfacing the patellae resulted in higher costs ($13,296.63 vs $12,917.01) and lower quality-adjusted life year (5.37 vs 6.01) at 14 years. Sensitivity analysis suggests that if rates of secondary resurfacing are <0.5%, there was no cost difference.Conclusion
Over 14 years postoperative, patellar resurfacing appears to be cost-effective, due to higher revision rates for unresurfaced TKA. Although our results suggest resurfacing improves quality of life, our model is limited by the availability and validity of long-term utility outcomes reported for TKA. Our cost-effectiveness analysis showed superiority of the resurfacing compared to retention of the patella. 相似文献999.
Fiala M Liu QN Sayre J Pop V Brahmandam V Graves MC Vinters HV 《European journal of clinical investigation》2002,32(5):360-371
BACKGROUND: Monocyte/macrophages are known to infiltrate the brain of patients with HIV-1 encephalitis (HIVE). In Alzheimer's disease brain, the origin of activated microglia has not been determined. MATERIALS AND METHODS: We employed the antigen retrieval technique, immunocytochemistry, immunofluorescense, and confocal microscopy to identify macrophages and microglia in relation to amyloid-beta plaques and the blood-brain barrier in autopsy brain tissues from patients with Alzheimer's disease (AD) and HIVE. RESULTS: In both conditions, cyclooxygenase-2 positive macrophages and, to a lesser degree, T and B cells infiltrate brain perivascular spaces and neuropil. The macrophages are distinguishable from ramified microglia, and decorate the vessels at the sites of apparent of endothelial tight junction protein ZO-1 disruption. The macrophages also infiltrate amyloid-beta plaques, display intracellular amyloid-beta and are surrounded by amyloid-beta-free lacunae. Furthermore, the macrophages partially encircle the walls of amyloid-beta-containing vessels in amyloid angiopathy, and exhibit intracellular amyloid-beta but not paracellular lacunae. Significantly larger zones of fibrinogen leakage surround the microvessels in HIVE brain tissues compared with AD tissues (P = 0.034), and AD tissues have significantly greater leakage than control tissues (P = 0.0339). The AD group differs from a normal control age-matched group with respect to both the area occupied by CD68 (P = 0.03) and cyclooxygenase-2 immunoreactive cells (P = 0.004). CONCLUSION: In both HIVE and AD, blood-borne activated monocyte/macrophages and lymphocytes appear to migrate through a disrupted blood-brain barrier. The lacunae around macrophages in amyloid-beta plaques but not in vessel walls are consistent with the ability of macrophages to phagocytize and clear amyloid-beta deposits in vitro. 相似文献
1000.
Transfer of specific unresponsiveness to organ allografts by thymocytes. Specific unresponsiveness by thymocyte transfer
下载免费PDF全文
![点击此处可从《The Journal of experimental medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
W S Hendry N L Tilney W M Baldwin M J Graves E Milford T B Strom C B Carpenter 《The Journal of experimental medicine》1979,149(5):1042-1055
Prolonged survival of vascularized organ allografts has been produced in unmodified inbred rats by transfer of thymocytes from enhanced, engrafted, syngeneic animals. For these thymocytes to increase significantly the survival of test allografts they must be harvested 6-9 d after transplantation. Thymectomy of the enhanced, engrafted animals during the same critical period causes acute rejection of othewise long surviving grafts. For optimal effect, the enhanced thymocyte donor must be actively and passively immunized and receive a cardiac allograft. The necessity for erythrocytes in the initial active immunization regimen is noted. Additionally, the antigenic specificity of the suppressor effect has been established with two histoincompatible donor rat strains. Cellular and humoral host responses mounted by test graft recipients after thymocyte transfer from enhanced, engrafted donors are different from those mounted either by unmodifed animals acutely rejecting their grafts or by enhanced rats bearing well-functioning grafts. Numbers of T lymphocytes are reduced in the grafted hearts and in the spleens of test graft recipients, a finding paralleled by the complete absence of specific direct lymphocyte-mediated cytotoxicity. In contrast, cytotoxic antibody production, although delayed, is increased in magnitude, peaking around the time of graft rejection. These studies provide evidence that different biological manipulations can modify separate pathways in the complex cellular and humoral responses towards organ allografts. They demonstrate that cellular immunity is critically involved in immunological enhancement of vascularized organ allografts, a phenomenon hitherto considered primarily humoral. It seems clear that cells with suppressor activity are present within the thymus during the early phases of immunological enhancement. 相似文献