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   10910篇
  免费   938篇
  国内免费   46篇
耳鼻咽喉   77篇
儿科学   346篇
妇产科学   257篇
基础医学   1760篇
口腔科学   89篇
临床医学   1231篇
内科学   2342篇
皮肤病学   255篇
神经病学   1203篇
特种医学   277篇
外科学   1254篇
综合类   45篇
现状与发展   1篇
一般理论   6篇
预防医学   857篇
眼科学   210篇
药学   631篇
中国医学   11篇
肿瘤学   1042篇
  2024年   24篇
  2023年   146篇
  2022年   248篇
  2021年   512篇
  2020年   324篇
  2019年   478篇
  2018年   450篇
  2017年   359篇
  2016年   362篇
  2015年   401篇
  2014年   541篇
  2013年   609篇
  2012年   981篇
  2011年   974篇
  2010年   525篇
  2009年   376篇
  2008年   701篇
  2007年   687篇
  2006年   612篇
  2005年   648篇
  2004年   524篇
  2003年   472篇
  2002年   415篇
  2001年   55篇
  2000年   33篇
  1999年   48篇
  1998年   92篇
  1997年   69篇
  1996年   36篇
  1995年   35篇
  1994年   23篇
  1993年   23篇
  1992年   7篇
  1991年   3篇
  1990年   8篇
  1989年   3篇
  1988年   3篇
  1987年   6篇
  1986年   6篇
  1985年   7篇
  1984年   5篇
  1983年   4篇
  1982年   4篇
  1981年   6篇
  1980年   3篇
  1978年   3篇
  1967年   3篇
  1933年   2篇
  1932年   2篇
  1928年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
A retrospective review is presented of 1353 consecutivepatients with histopathologically confirmed invasive breast carcinoma treatedradically with curative intent during the decade 1980–89.None had received adjuvant systemic therapy with hormonesor prolonged chemotherapy. The distribution of lymph-node negative(N–) and lymph-node positive (N+) patients was 75%and 25%, respectively.The treatment and outcome were analysed as regardsconventional prognostic parameters, in particular considering the axillarylymph-node status and the responsible hospital category (GeneralMunicipal Hospitals (MH)) versus Comprehensive Cancer Center (CC)).The most striking difference was detected as regardsthe number of examined lymph nodes. The mediannumber of nodes described at the MH was7, as compared to 14 at the CC(p < 0.001). In patients with pT1 tumoursthe highest rate of lymph-node positivity was observedwhen 10 or more axillary nodes were removed.Adjuvant radiotherapy reduced the loco-regional recurrence rate inthe N– patients, whereas only the regional recurrenceswere reduced among the N+ patients. The five-and 10-year tumor-related survival rates were 86% and76%, respectively, with no difference between the MHand the CC.As life-prolonging adjuvant hormone therapy and chemotherapy isnow available for patients with axillary lymph nodemetastases, it is important that patients with breastcancer are operated adequately with the aim toremove at least 10 axillary lymph nodes. Athorough examination of the axillary content should beperformed by the pathologist, and the number ofresected lymph nodes and metastases should be reported.The establishment of nation-wide standard criteria for themanagement of breast cancer is recommended.  相似文献   
42.
OBJECTIVE: To investigate the relationship between overweight and obesity, and mental health problems in Australian 4- to 5-year-old children. METHODS: The study used data from wave 1 (2004) of the Longitudinal Study of Australian Children (LSAC). The participants were 4983 4- to 5-year-old children (2537 boys and 2446 girls) with a mean age of 56.9 months (standard deviation 2.6 months; range 51-67 months). Children were classified as nonoverweight, overweight, and obese on the basis of International Obesity Task Force definitions. Mental health problems were assessed by the Strengths and Difficulties Questionnaire (SDQ) completed by parents and teachers. RESULTS: Although obese 4- to 5-year-old boys had more mental health problems than nonoverweight boys, differences between the groups were small and substantially reduced when analyses controlled for children's sociodemographic characteristics. Parents reported that overweight/obese girls had more peer problems, whereas teachers reported they had more conduct problems. Children in all weight groups had mean scores within the normal range of scores on all the SDQ subscales. CONCLUSIONS: Differences in rates of mental health problems experienced by young children of different weight status appear relatively small. Higher rates of mental health problems experienced by more obese boys may reflect differences in their sociodemographic characteristics rather than their weight status per se. Policies that reduce the number of young children living in poverty or experiencing other adverse social circumstances have the potential to reduce rates of mental health problems experienced by older children with overweight/obesity.  相似文献   
43.
Acetaldehyde, the first product of ethanol metabolism, has been suggested to play a major role in many behavioral effects of ethanol. However, very few studies have directly tested the behavioral effects of the acute administration of acetaldehyde. In particular, the role of this metabolite in ethanol-induced anxiolytic effects has never been extensively tested. The aim of the present study was to characterize the anxiolytic effects of acetaldehyde in two strains of mice, C57BL/6J and CD1 mice with the elevated plus-maze procedure. The results show that acute injections of ethanol (1–2 g/kg) induced significant dose-dependent anxiolytic effects in both strains of mice. In contrast, acetaldehyde failed to produce any anxiolytic effect, although it induced a significant hypolocomotor effect at the highest doses. In an independent experiment, cyanamide, an aldehyde dehydrogenase inhibitor, prevented the locomotor stimulant effects of ethanol, although it failed to alter its anxiolytic effects. Together, the results of the present study indicate that acetaldehyde is not involved in ethanol-induced anxiolytic effects, although it may be involved in its sedative/hypolocomotor effects.  相似文献   
44.
Mental health problems are common in children and adolescents, yet evidence-based treatments are hard to access. Self-help interventions can increase such access. The aim of this paper was to conduct a systematic review and meta-analysis of the use of guided and unguided self-help for children and young people with symptoms of common mental health disorders. In contrast to previous reviews of self-help in children, all types of self-help and multiple mental health disorders were investigated in order to increase power to investigate potential moderators of efficacy. Importantly, studies with control arms as well as those comparing against traditional face-to-face treatments were included. Fifty studies (n = 3396 participants in self-help/guided self-help conditions) met the inclusion criteria. Results demonstrated a moderate positive effect size for guided and unguided self-help interventions when compared against a control group (n = 44; g = 0.49; 95% CI: 0.37 to 0.61, p < .01) and a small but significant negative effect size when compared to other therapies (n = 15; g = −0.17; 95% CI: –0.27 to –0.07, p < .01). Few potential moderators had a significant effect on outcome. Most comparisons resulted in significant heterogeneity and therefore results are interpreted with caution.  相似文献   
45.
46.
Coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 is associated with a wide spectrum of disease, ranging from asymptomatic infection to acute respiratory distress syndrome. Some biomarkers may predict disease severity. Among them, the anti-SARS-CoV-2 antibody response has been related to severe disease. The aim of this study was to assess the correlation between the anti-SARS-CoV-2 serological response and COVID-19 outcome. Demographic, clinical, and biological data from nasopharyngeal-PCR confirmed COVID-19 hospitalized patients were prospectively collected between April and August 2020 at our institution. All patients had serial weekly serology testing for a maximum of three blood samples or until discharge. Two different serological assays were used: a chemiluminescent assay and an in-house developed Luminex immunoassay. Kinetics of the serological response and correlation between the antibody titers and outcome were assessed. Among the 70 patients enrolled in the study, 22 required invasive ventilation, 29 required non-invasive ventilation or oxygen supplementation, and 19 did not require any oxygen supplementation. Median duration of symptoms upon admission for the three groups were 13, 8, and 9 days, respectively. Antibody titers gradually increased for up to 3 weeks since the onset of symptoms for patients requiring oxygen supplementation with significantly higher antibody titers for patients requiring invasive ventilation. Antibody titers on admission were also significantly higher in severely ill patients and serology performed well in predicting the necessity of invasive ventilation (AUC: 0.79, 95% CI: 0.67–0.9). Serology testing at admission may be a good indicator to identify severe COVID-19 patients who will require invasive mechanical ventilation.  相似文献   
47.
48.
Adsorption of particles across interfaces has been proposed as a way to create adhesion between hydrogels and biological tissues. Here, we explore how this particle bridging approach can be applied to attach a soft polymer substrate to biological tissues, using bioresorbable and nanostructured hydroxyapatite–bioactive glass microparticles. For this, microparticles of aggregated flower-like hydroxyapatite and bioactive glass (HA–BG) were synthesized via a bioinspired route. A deposition technique using suspension spreading was developed to tune the coverage of HA–BG coatings at the surface of weakly cross-linked poly(beta-thioester) films. By varying the concentration of the deposited suspensions, we produced coatings having surface coverages ranging from 4% to 100% and coating densities ranging from 0.02 to 1.0 mg cm−2. The progressive dissolution of these coatings within 21 days in phosphate-buffered saline was followed by SEM. Ex vivo peeling experiments on pig liver capsules demonstrated that HA–BG coatings produce an up-to-two-fold increase in adhesion energy (9.8 ± 1.5 J m−2) as compared to the uncoated film (4.6 ± 0.8 J m−2). Adhesion energy was found to increase with increasing coating density until a maximum at 0.2 mg cm−2, well below full surface coverage, and then it decreased for larger coating densities. Using microscopy observations during and after peeling, we show that this maximum in adhesion corresponds to the appearance of particle stacks, which are easily separated and transferred onto the tissue. Such bioresorbable HA–BG coatings give the possibility of combining particle bridging with the storage and release of active compounds, therefore offering opportunities to design functional bioadhesive surfaces.

Coatings of hydroxyapatite–bioactive glass microparticles are proposed as a way to create adhesion between hydrogels and biological tissues using adsorption of the microparticles across the interface.  相似文献   
49.
50.
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