全文获取类型
收费全文 | 70906篇 |
免费 | 6312篇 |
国内免费 | 142篇 |
专业分类
耳鼻咽喉 | 809篇 |
儿科学 | 2013篇 |
妇产科学 | 1633篇 |
基础医学 | 10496篇 |
口腔科学 | 1831篇 |
临床医学 | 9060篇 |
内科学 | 13355篇 |
皮肤病学 | 1100篇 |
神经病学 | 6806篇 |
特种医学 | 2039篇 |
外国民族医学 | 2篇 |
外科学 | 7943篇 |
综合类 | 1193篇 |
现状与发展 | 1篇 |
一般理论 | 63篇 |
预防医学 | 7515篇 |
眼科学 | 1602篇 |
药学 | 5058篇 |
1篇 | |
中国医学 | 69篇 |
肿瘤学 | 4771篇 |
出版年
2023年 | 395篇 |
2022年 | 647篇 |
2021年 | 1409篇 |
2020年 | 916篇 |
2019年 | 1471篇 |
2018年 | 1686篇 |
2017年 | 1292篇 |
2016年 | 1402篇 |
2015年 | 1538篇 |
2014年 | 2169篇 |
2013年 | 2947篇 |
2012年 | 4433篇 |
2011年 | 4605篇 |
2010年 | 2488篇 |
2009年 | 2316篇 |
2008年 | 3949篇 |
2007年 | 4111篇 |
2006年 | 3741篇 |
2005年 | 3899篇 |
2004年 | 3510篇 |
2003年 | 3315篇 |
2002年 | 3168篇 |
2001年 | 1329篇 |
2000年 | 1286篇 |
1999年 | 1349篇 |
1998年 | 766篇 |
1997年 | 628篇 |
1996年 | 588篇 |
1995年 | 566篇 |
1994年 | 517篇 |
1993年 | 501篇 |
1992年 | 972篇 |
1991年 | 941篇 |
1990年 | 948篇 |
1989年 | 865篇 |
1988年 | 805篇 |
1987年 | 796篇 |
1986年 | 745篇 |
1985年 | 751篇 |
1984年 | 594篇 |
1983年 | 533篇 |
1982年 | 358篇 |
1981年 | 378篇 |
1980年 | 349篇 |
1979年 | 500篇 |
1978年 | 406篇 |
1977年 | 338篇 |
1974年 | 398篇 |
1973年 | 376篇 |
1971年 | 318篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
James A. Akingbasote Alison J. Foster Ian Wilson Sunil Sarda Huw B. Jones J. Gerry Kenna 《Archives of toxicology》2016,90(4):853-862
Hepatic NADPH-cytochrome P450 oxidoreductase null (HRN?) mice exhibit normal hepatic and extrahepatic biotransformation enzyme activities when compared to wild-type (WT) mice, but express no functional hepatic cytochrome P450 activities. When incubated in vitro with [14C]-diclofenac, liver microsomes from WT mice exhibited extensive biotransformation to oxidative and glucuronide metabolites and covalent binding to proteins was also observed. In contrast, whereas glucuronide conjugates and a quinone-imine metabolite were formed when [14C]-diclofenac was incubated with HRN? mouse liver, only small quantities of P450-derived oxidative metabolites were produced in these samples and covalent binding to proteins was not observed. Livers from vehicle-treated HRN? mice exhibited enhanced lipid accumulation, bile duct proliferation, hepatocellular degeneration and necrosis and inflammatory cell infiltration, which were not present in livers from WT mice. Elevated liver-derived alanine aminotransferase, glutamate dehydrogenase and alkaline phosphatase activities were also observed in plasma from HRN? mice. When treated orally with diclofenac for 7 days, at 30 mg/kg/day, the severities of the abnormal liver histopathology and plasma liver enzyme findings in HRN? mice were reduced markedly. Oral diclofenac administration did not alter the liver histopathology or elevate plasma enzyme activities of WT mice. These findings indicate that HRN? mice are valuable for exploration of the role played by hepatic P450s in drug biotransformation, but poorly suited to investigations of drug-induced liver toxicity. Nevertheless, studies in HRN? mice could provide novel insights into the role played by inflammation in liver injury and may aid the evaluation of new strategies for its treatment. 相似文献
2.
Rocha Déborah Ribeiro Nery Jaqueline Freire Furini Leonardo Negri Constantino Carlos José Leopoldo Eller Lizziane Kretli Winkelströter Nai Gisele Alborghetti Nakagaki Wilson Romero 《Lasers in medical science》2020,35(8):1703-1709
Lasers in Medical Science - Studies reported the harmful effects of 2,4-D on body tissues, provoking changes in the anatomy and physiology of the kidneys, liver, and testicles. Thus, the objective... 相似文献
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.
Leyi Wang Saraswathi Lanka Debbie Cassout Nohra E. Mateus‐Pinilla Ganwu Li William C. Wilson Dongwan Yoo Paul Shelton Richard L. Fredrickson 《Transboundary and Emerging Diseases》2019,66(5):1809-1820
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year. 相似文献
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.
To increase the overall rate of breastfeeding initiation and duration, factors involved in a mother's decision to breastfeed must be identified. Self‐objectification in the context of breastfeeding was a concept selected for exploring factors associated with negative views of breastfeeding. A concept analysis following the eight‐step Walker & Avant method provides clarity and context to the concept of self‐objectification in the context of breastfeeding. The antecedents of self‐objectification in the context of breastfeeding include living in a culture of sexualization and objectification of women and the internalization of the values of objectification. Attributes of self‐objectification in the context of breastfeeding are a prioritization of physical appearance attributes of the breast over the health benefits of breastfeeding and a preoccupation with physical appearance. Consequences include negative views toward breastfeeding initiation, duration, and public breastfeeding. A concept analysis on self‐objectification in the context of breastfeeding will provide definition and clarity to this phenomenon, lend to theory and measurement, and add literature to the sociocultural factors impacting breastfeeding decisions. 相似文献
10.