全文获取类型
收费全文 | 49193篇 |
免费 | 3714篇 |
国内免费 | 135篇 |
专业分类
耳鼻咽喉 | 450篇 |
儿科学 | 1285篇 |
妇产科学 | 1094篇 |
基础医学 | 6582篇 |
口腔科学 | 977篇 |
临床医学 | 4894篇 |
内科学 | 9388篇 |
皮肤病学 | 803篇 |
神经病学 | 4833篇 |
特种医学 | 1655篇 |
外科学 | 7837篇 |
综合类 | 700篇 |
现状与发展 | 1篇 |
一般理论 | 39篇 |
预防医学 | 4202篇 |
眼科学 | 1194篇 |
药学 | 3260篇 |
中国医学 | 125篇 |
肿瘤学 | 3723篇 |
出版年
2023年 | 235篇 |
2022年 | 376篇 |
2021年 | 1010篇 |
2020年 | 627篇 |
2019年 | 912篇 |
2018年 | 1160篇 |
2017年 | 840篇 |
2016年 | 851篇 |
2015年 | 1006篇 |
2014年 | 1513篇 |
2013年 | 2080篇 |
2012年 | 3232篇 |
2011年 | 3376篇 |
2010年 | 1913篇 |
2009年 | 1730篇 |
2008年 | 3041篇 |
2007年 | 3302篇 |
2006年 | 3081篇 |
2005年 | 3023篇 |
2004年 | 2911篇 |
2003年 | 2739篇 |
2002年 | 2524篇 |
2001年 | 669篇 |
2000年 | 658篇 |
1999年 | 663篇 |
1998年 | 556篇 |
1997年 | 504篇 |
1996年 | 473篇 |
1995年 | 405篇 |
1994年 | 377篇 |
1993年 | 358篇 |
1992年 | 497篇 |
1991年 | 436篇 |
1990年 | 365篇 |
1989年 | 363篇 |
1988年 | 326篇 |
1987年 | 343篇 |
1986年 | 319篇 |
1985年 | 348篇 |
1984年 | 277篇 |
1983年 | 285篇 |
1982年 | 289篇 |
1981年 | 257篇 |
1980年 | 232篇 |
1979年 | 218篇 |
1978年 | 201篇 |
1977年 | 205篇 |
1976年 | 181篇 |
1975年 | 170篇 |
1974年 | 162篇 |
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
1.
Lauren Tingey Britta Mullany Rachel Chambers Ranelda Hastings Angelita Lee Anthony Parker 《AIDS care》2015,27(9):1087-1097
Potential for widespread transmission of HIV/AIDS among American Indian (AI) adolescents exists, yet no evidence-based interventions (EBIs) have been adapted and evaluated with this population. Intensive psychoeducation may improve knowledge and decision-making which could potentially translate to reductions in HIV risk behaviors. A peer group randomized controlled comparison of an adapted EBI vs. control was delivered over an eight-day summer basketball camp in one reservation-based tribal community to adolescents ages 13–19. Outcome data were gathered immediately post-camp and at 6 and 12 months follow-up. Self-selected peer groups were randomized to intervention (n = 138) or control (n = 129) conditions for a total sample of 267 participants (56.2% female), mean age 15.1 years (SD = 1.7). Intervention participants had better condom use self-efficacy post-camp (Adjusted Mean Difference [AMD] = ?0.75, p < 0.005) and at 6 (AMD = ?0.44, p < 0.005) and 12 months (AMD = ?0.23, p < 0.05) follow-up. Intervention participants also had higher HIV prevention and transmission knowledge (post-camp: AMD = 0.07, p < 0.01; 6 months: AMD = 0.06, p < 0.01) were more likely to believe condoms prevent sexually transmitted infections (post-camp: RR = 1.41, p < 0.005; 6 months: RR = 1.34, p < 0.05), to talk with an adult about HIV/AIDS (post-camp: RR=1.78, p < 0.005; 6 months: RR = 1.14, p < 0.005), had higher partner negotiation efficacy related to substance use during sex (post-camp: AMD = 0.37, p < 0.01), and were more likely to intend to use a condom (post-camp: RR = 1.39, p < 0.01). The adapted intervention had short- and medium-term impacts on AI adolescent risk for HIV/AIDS, but attenuated at 12 months. Intervention delivery through a community-based camp is feasible and acceptable with strong retention. Additional study is needed to evaluate the adapted intervention's impact on sexual risk behaviors and if booster sessions and parent involvement translate to long-term impacts. 相似文献
2.
3.
4.
Angela J. Jacques-Tiura Deborah A. Ellis April Idalski Carcone Sylvie Naar Kathryn Brogan Hartlieb Elizabeth K. Towner Thomas N. Templin K.-L. Catherine Jen 《The Journal of adolescent health》2019,64(3):355-361
Objective
Successful weight loss interventions for African-Americans adolescents are lacking. Cognitive-behavioral interventions seek to develop weight loss skills (e.g., counting calories, goal setting, managing one's environment). Little is known about how well adolescents implement such skills in their daily lives. Study aims were to (1) examine weight loss skills utilization at midpoint and end of a 6-month cognitive-behavioral/motivational interviewing weight loss sequential multiple assignment randomized trial (SMART), and (2) determine if greater skill utilization predicted weight loss at treatment end and 3 months post-treatment.Method
One hundred and eighty six African-Americans adolescents with obesity and their caregiver were first randomly assigned to complete 3 months of cognitive-behavioral and motivational interviewing family-based weight loss treatment in their home or in the research office (Phase 1). Nonresponders (i.e., those who lost < 3% of initial weight, n?=?161) were rerandomized to 3 months of continued skills training (n?=?83) or contingency management (n?=?78) for Phase 2; responders were allocated to 3 months of relapse prevention (n?=?20). Adolescents’ frequency of weight loss skills utilization was assessed via questionnaire at treatment midpoint and end.Results
Higher treatment attendance was associated with better skill utilization. Higher skill utilization was associated with more weight loss at treatment end, whereas higher baseline confidence was associated with more weight loss at follow-up.Conclusions
This study indicates the importance of attending weight loss intervention sessions to develop and strengthen weight loss skills in African-American adolescents with obesity, and strengthening confidence to use such skills for continued weight loss. 相似文献5.
6.
7.
Alan. B. Franklin Sarah N. Bevins Jeremy W. Ellis Ryan S. Miller Susan A. Shriner J. Jeffrey Root Daniel P. Walsh Thomas J. Deliberto 《Transboundary and Emerging Diseases》2019,66(2):705-714
Using data on waterfowl band recoveries, we identified spatially explicit hotspots of concentrated waterfowl movement to predict occurrence and spatial spread of a novel influenza A virus (clade 2.3.4.4) introduced from Asia by waterfowl from an initial outbreak in North America in November 2014. In response to the outbreak, the hotspots of waterfowl movement were used to help guide sampling for clade 2.3.4.4 viruses in waterfowl as an early warning for the US poultry industry during the outbreak . After surveillance sampling of waterfowl, we tested whether there was greater detection of clade 2.3.4.4 viruses inside hotspots. We found that hotspots defined using kernel density estimates of waterfowl band recoveries worked well in predicting areas with higher prevalence of the viruses in waterfowl. This approach exemplifies the value of ecological knowledge in predicting risk to agricultural security. 相似文献
8.
9.
10.
Anthony R. Flores Brittany E. Jewell Erika M. Versalovic Randall J. Olsen Beth A. Bachert Slawomir Lukomski James M. Musser 《Infection and immunity》2015,83(3):1122-1129
Group A Streptococcus (GAS) predominantly exists as a colonizer of the human oropharynx that occasionally breaches epithelial barriers to cause invasive diseases. Despite the frequency of GAS carriage, few investigations into the contributory molecular mechanisms exist. To this end, we identified a naturally occurring polymorphism in the gene encoding the streptococcal collagen-like protein A (SclA) in GAS carrier strains. All previously sequenced invasive serotype M3 GAS possess a premature stop codon in the sclA gene truncating the protein. The carrier polymorphism is predicted to restore SclA function and was infrequently identified by targeted DNA sequencing in invasive strains of the same serotype. We demonstrate that a strain with the carrier sclA allele expressed a full-length SclA protein, while the strain with the invasive sclA allele expressed a truncated variant. An isoallelic mutant invasive strain with the carrier sclA allele exhibited decreased virulence in a mouse model of invasive disease and decreased multiplication in human blood. Further, the isoallelic invasive strain with the carrier sclA allele persisted in the mouse nasopharynx and had increased adherence to cultured epithelial cells. Repair of the premature stop codon in the invasive sclA allele restored the ability to bind the extracellular matrix proteins laminin and cellular fibronectin. These data demonstrate that a mutation in GAS carrier strains increases adherence and decreases virulence and suggest selection against increased adherence in GAS invasive isolates. 相似文献