全文获取类型
收费全文 | 144420篇 |
免费 | 31156篇 |
国内免费 | 1333篇 |
专业分类
耳鼻咽喉 | 3105篇 |
儿科学 | 3346篇 |
妇产科学 | 3039篇 |
基础医学 | 8427篇 |
口腔科学 | 6375篇 |
临床医学 | 28910篇 |
内科学 | 35732篇 |
皮肤病学 | 3941篇 |
神经病学 | 16015篇 |
特种医学 | 5227篇 |
外科学 | 26197篇 |
综合类 | 308篇 |
现状与发展 | 40篇 |
一般理论 | 2篇 |
预防医学 | 14677篇 |
眼科学 | 2862篇 |
药学 | 4971篇 |
中国医学 | 102篇 |
肿瘤学 | 13633篇 |
出版年
2024年 | 753篇 |
2023年 | 5235篇 |
2022年 | 1582篇 |
2021年 | 3504篇 |
2020年 | 5679篇 |
2019年 | 2558篇 |
2018年 | 7469篇 |
2017年 | 7787篇 |
2016年 | 8507篇 |
2015年 | 8659篇 |
2014年 | 11250篇 |
2013年 | 13232篇 |
2012年 | 5672篇 |
2011年 | 5565篇 |
2010年 | 8001篇 |
2009年 | 10057篇 |
2008年 | 5540篇 |
2007年 | 4622篇 |
2006年 | 5816篇 |
2005年 | 4366篇 |
2004年 | 3742篇 |
2003年 | 3475篇 |
2002年 | 3382篇 |
2001年 | 3522篇 |
2000年 | 2976篇 |
1999年 | 3304篇 |
1998年 | 2723篇 |
1997年 | 2426篇 |
1996年 | 2431篇 |
1995年 | 2102篇 |
1994年 | 1477篇 |
1993年 | 1267篇 |
1992年 | 1900篇 |
1991年 | 1622篇 |
1990年 | 1462篇 |
1989年 | 1513篇 |
1988年 | 1363篇 |
1987年 | 1227篇 |
1986年 | 1155篇 |
1985年 | 1082篇 |
1984年 | 797篇 |
1983年 | 742篇 |
1982年 | 467篇 |
1981年 | 383篇 |
1980年 | 324篇 |
1979年 | 558篇 |
1978年 | 407篇 |
1977年 | 380篇 |
1974年 | 301篇 |
1972年 | 278篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Milos Jesenak MD PhD Peter Banovcin MD PhD Zuzana Rennerova MD PhD Lubica Jakusova MD PhD Zuzana Havlicekova MD PhD Vladimir Pohanka MD PhD MPH FCCP Maria Pia Villa MD PhD Roberto Ronchetti MD PhD 《International journal of dermatology》2009,48(9):941-946
Background The atopy patch test (APT) is no longer an experimental method; it is increasingly being used as a standard diagnostic tool for the characterization of patients with aeroallergen- and food-triggered disorders. Some technical aspects of this test still remain to be answered. We aimed to study the reproducibility of this test over time in the general child population.
Methods In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances. 相似文献
Methods In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances. 相似文献
52.
Ludger Grote MD PhD Lena Leissner MD Jan Hedner MD PhD Jan Ulfberg MD PhD 《Movement disorders》2009,24(10):1445-1452
Iron deficiency may exacerbate symptoms in the Restless Legs Syndrome (RLS). We investigated the effect of intravenous iron sucrose or placebo on symptoms in patients with RLS and mild to moderate iron deficit. Sixty patients with primary RLS (seven males, age 46 (9) years, S‐ferritin ≤45 μg/L) recruited from a cohort of 231 patients were randomly assigned in a 12‐months double‐blind, multi‐centre study of iron sucrose 1000 mg (n = 29) or saline (n = 31). The primary efficacy variable was the RLS severity scale (IRLS) score at week 11. Median IRLS score decreased from 24 to 7 (week 11) after iron sucrose and from 26 to 17 after placebo (P = 0.123, N.S. for between treatment comparison). The corresponding scores at week 7 were 12 and 20 in the two groups (P = 0.017). Drop out rate because of lack of efficacy at 12 months was 19/31 after placebo and 5/29 patients after iron sucrose (Kaplan–Meier estimate, log rank test P = 0.0006) suggesting an iron induced superior long term RLS symptom control. Iron sucrose was well tolerated. This study showed a lack of superiority of iron sucrose at 11 weeks but found evidence that iron sucrose reduced RLS symptoms both in the acute phase (7 weeks) and during long‐term follow up in patients with variable degree of iron deficiency. Further studies on target patient groups, dosing and dosing intervals are warranted before iron sucrose could be considered for treatment of iron deficient patients with RLS. © 2009 Movement Disorder Society 相似文献
53.
54.
Leonard A. Jason PhD Steven B. Pokorny PhD Monica Adams MPH Annie Topliff MA Courtney Harris BA Yvonne Hunt PhD 《The American journal on addictions / American Academy of Psychiatrists in Alcoholism and Addictions》2009,18(5):367-374
This study evaluated the effects of tobacco Purchase, Use and Possession (PUP) laws on student perceptions of adolescent tobacco use within towns and schools. Twenty‐four towns were randomly assigned into two conditions, the experimental condition (E PUP) involved efforts to increase both PUP law enforcement and reduce minors' access to commercial sources of tobacco, whereas the control condition (C) focused only on efforts to reduce minors' access to commercial sources of tobacco. A hierarchical linear modeling analytical approach was selected due to the multilevel data and nested design. The present study found that over time, youth in the experimental PUP condition observed less youth tobacco usage at school and in their town, and perceived lower rates of tobacco among their peers at school and among friends than youth in the control condition. The findings suggest that PUP law enforcement might be used to strengthen community norms against youth tobacco use. 相似文献
55.
56.
57.
58.
59.
Yasuo Suzuki 《Journal of neuro-ophthalmology》2007,27(2):138-142
Kenji Ohtsuka, MD and his colleagues at the Sapporo Medical University have investigated the central organization of the near response with anatomical and neurophysiologic studies in cats. Based on their data and clinical observations, they proposed that the rostral pole of the superior colliculus has a critical role in the control of accommodation, vergence, and fixation. Although the central pathways have yet to be fully worked out, the contributions of Dr. Ohtsuka, who died in 2005, have laid an important foundation in the understanding of these functions. 相似文献
60.
Color Stability of Dry Earth Pigmented Maxillofacial Silicone A-2186 Subjected to Microwave Energy Exposure 总被引:2,自引:0,他引:2
Sudarat Kiat-amnuay DDS MS ; Dennis A. Johnston PhD ; John M. Powers PhD ; Rhonda F. Jacob DDS MS 《Journal of prosthodontics》2005,14(2):91-96
PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments. 相似文献