全文获取类型
收费全文 | 35119篇 |
免费 | 2715篇 |
国内免费 | 95篇 |
专业分类
耳鼻咽喉 | 336篇 |
儿科学 | 1048篇 |
妇产科学 | 903篇 |
基础医学 | 5371篇 |
口腔科学 | 472篇 |
临床医学 | 5023篇 |
内科学 | 6214篇 |
皮肤病学 | 725篇 |
神经病学 | 3942篇 |
特种医学 | 810篇 |
外科学 | 3208篇 |
综合类 | 277篇 |
现状与发展 | 1篇 |
一般理论 | 33篇 |
预防医学 | 3733篇 |
眼科学 | 606篇 |
药学 | 2296篇 |
中国医学 | 42篇 |
肿瘤学 | 2889篇 |
出版年
2024年 | 32篇 |
2023年 | 278篇 |
2022年 | 431篇 |
2021年 | 896篇 |
2020年 | 601篇 |
2019年 | 928篇 |
2018年 | 1107篇 |
2017年 | 862篇 |
2016年 | 943篇 |
2015年 | 973篇 |
2014年 | 1381篇 |
2013年 | 1783篇 |
2012年 | 2815篇 |
2011年 | 2890篇 |
2010年 | 1568篇 |
2009年 | 1431篇 |
2008年 | 2441篇 |
2007年 | 2505篇 |
2006年 | 2263篇 |
2005年 | 2359篇 |
2004年 | 2102篇 |
2003年 | 1956篇 |
2002年 | 1841篇 |
2001年 | 254篇 |
2000年 | 154篇 |
1999年 | 293篇 |
1998年 | 391篇 |
1997年 | 325篇 |
1996年 | 238篇 |
1995年 | 239篇 |
1994年 | 192篇 |
1993年 | 180篇 |
1992年 | 123篇 |
1991年 | 109篇 |
1990年 | 92篇 |
1989年 | 101篇 |
1988年 | 84篇 |
1987年 | 71篇 |
1986年 | 61篇 |
1985年 | 51篇 |
1984年 | 71篇 |
1983年 | 52篇 |
1982年 | 59篇 |
1981年 | 66篇 |
1980年 | 66篇 |
1979年 | 31篇 |
1978年 | 30篇 |
1977年 | 37篇 |
1976年 | 29篇 |
1974年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 343 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.
8.
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9.
Eloise R. Galligan Lindsey Fix Sameera Husain Philip Zachariah Darrell J. Yamashiro Christine T. Lauren 《Journal of cutaneous pathology》2019,46(2):159-161
We report a case of disseminated Trichosporon asahii in a patient on systemic antifungal therapy who presented with multiple cutaneous nodules suggestive of fungal infection. Histologic features resembled neutrophilic eccrine hidradenitis but staining with periodic acid‐Schiff and Gomori methenamine silver confirmed the clinical diagnosis. This case highlights the importance of maintaining suspicion for trichosporonosis and contextualizing histologic findings within the underlying clinical picture. 相似文献
10.
Eloise R. Galligan Leila H. Shayegan Christine T. Lauren Kimberly D. Morel 《Pediatric dermatology》2019,36(5):753-754
Shaving and other modes of epilation can cause undue anxiety, pain, or skin irritation in children. Here, we present hair trimming as a safe, painless, and cost‐effective alternative for patients with unwanted hair which may be performed indefinitely or until the child is old enough to direct management. In select cases, removing unwanted hair using this technique may facilitate dermatologic surveillance. 相似文献