全文获取类型
| 收费全文 | 44838篇 |
| 免费 | 3713篇 |
| 国内免费 | 106篇 |
专业分类
| 耳鼻咽喉 | 417篇 |
| 儿科学 | 1359篇 |
| 妇产科学 | 1057篇 |
| 基础医学 | 6835篇 |
| 口腔科学 | 803篇 |
| 临床医学 | 6081篇 |
| 内科学 | 7982篇 |
| 皮肤病学 | 916篇 |
| 神经病学 | 4645篇 |
| 特种医学 | 1183篇 |
| 外科学 | 4524篇 |
| 综合类 | 511篇 |
| 现状与发展 | 1篇 |
| 一般理论 | 37篇 |
| 预防医学 | 4683篇 |
| 眼科学 | 799篇 |
| 药学 | 2911篇 |
| 中国医学 | 55篇 |
| 肿瘤学 | 3858篇 |
出版年
| 2023年 | 305篇 |
| 2022年 | 483篇 |
| 2021年 | 1021篇 |
| 2020年 | 679篇 |
| 2019年 | 1043篇 |
| 2018年 | 1247篇 |
| 2017年 | 976篇 |
| 2016年 | 1066篇 |
| 2015年 | 1120篇 |
| 2014年 | 1560篇 |
| 2013年 | 2135篇 |
| 2012年 | 3233篇 |
| 2011年 | 3336篇 |
| 2010年 | 1832篇 |
| 2009年 | 1670篇 |
| 2008年 | 2811篇 |
| 2007年 | 2962篇 |
| 2006年 | 2682篇 |
| 2005年 | 2759篇 |
| 2004年 | 2512篇 |
| 2003年 | 2333篇 |
| 2002年 | 2198篇 |
| 2001年 | 535篇 |
| 2000年 | 465篇 |
| 1999年 | 572篇 |
| 1998年 | 510篇 |
| 1997年 | 437篇 |
| 1996年 | 330篇 |
| 1995年 | 334篇 |
| 1994年 | 272篇 |
| 1993年 | 275篇 |
| 1992年 | 391篇 |
| 1991年 | 353篇 |
| 1990年 | 298篇 |
| 1989年 | 317篇 |
| 1988年 | 242篇 |
| 1987年 | 259篇 |
| 1986年 | 244篇 |
| 1985年 | 259篇 |
| 1984年 | 202篇 |
| 1983年 | 182篇 |
| 1982年 | 157篇 |
| 1981年 | 152篇 |
| 1980年 | 152篇 |
| 1979年 | 164篇 |
| 1978年 | 119篇 |
| 1977年 | 127篇 |
| 1976年 | 123篇 |
| 1974年 | 111篇 |
| 1972年 | 110篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
1.
2.
3.
Jeffrey Buenaflor Parker Sommerville Hang Qian Christine Luscombe 《Macromolecular chemistry and physics.》2020,221(2)
A comparative study involving bimetallic nickel catalysts designed from disubstituted N,N,N′,N′‐tetra(diphenylphosphanylmethyl)benzene diamine bridging ligands is reported. Catalyst behavior is explored in the Kumada catalyst‐transfer polymerization (KCTP) using poly(3‐hexylthiophene) (P3HT) as the model system. The success of a controlled polymerization is monitored by analyzing monomer conversion, degree of polymerization, end‐group identity, and molecular weight distribution. The characterization of P3HT obtained from KCTP initiated with the bimetallic catalysts shows chain‐growth behavior; however, the presence of Br/Br end‐groups and broader molecular weight distribution reveals a reduced controlled polymerization compared to the commonly employed Ni(dppp)Cl2. The observed increase in intermolecular chain transfer and termination processes in KCTP initiation with the bimetallic catalysts can be attributed to a weaker Ni(0)‐π‐aryl complex interaction, which is caused by increased steric crowding of the coordination sphere. 相似文献
4.
5.
6.
7.
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8.
9.
Sarah Averbach Othman Kakaire Rachel McDiehl Christine Dehlendorf Felicia Lester Jody Steinauer 《Contraception》2019,99(2):87-93
Objective
This study assessed whether immediate postpartum insertion of levonorgestrel contraceptive implants is associated with a difference in infant growth from birth to 6 months, onset of lactogenesis, or breastfeeding continuation at 3 and 6 months postpartum compared to delayed insertion at 6 to 8 weeks postpartum.Study design
We conducted a randomized trial of women in Uganda who desired contraceptive implants postpartum. We randomly assigned participants to receive either immediate (within 5 days of delivery) or delayed (6 to 8 weeks postpartum) insertion of a two-rod levonorgestrel contraceptive implant system. This is a prespecified secondary analysis evaluating breastfeeding outcomes. The primary outcome of this secondary analysis was change in infant weight; infants were weighed and measured at birth and 6 months. We used a validated questionnaire to assess onset of lactogenesis daily in person while participants were in the hospital, and then daily by phone after they left the hospital, until lactogenesis was documented. We used interviewer-administered questionnaires to assess breastfeeding continuation and concerns at 3 months and 6 months postpartum.Results
Among the 96 women randomized to the immediate group and the 87 women to the delayed group, the mean change in infant weight from birth to 6 months was similar between groups: 4632?g in the immediate group and 4407?g in the delayed group (p=.26). Among the 97 women who had not experienced lactogenesis prior to randomization, the median time to onset of lactogenesis did not differ significantly between the immediate and delayed groups (65?h versus 63?h; p=.84). Similar proportions of women in the immediate and delayed groups reported exclusive breastfeeding at 3 months (74% versus 71%; p=.74) and 6 months (48% versus 52%; p=.58).Conclusion
We found no association between the timing of postpartum initiation of levonorgestrel contraceptive implants and change in infant growth from birth to 6 months, onset of lactogenesis, or breastfeeding continuation at 3 or 6 months postpartum.Implications
This study provides evidence that immediate postpartum initiation of contraception implants does not have a deleterious effect on infant growth or initiation or continuation of breastfeeding. 相似文献10.