全文获取类型
收费全文 | 17638篇 |
免费 | 985篇 |
国内免费 | 68篇 |
专业分类
耳鼻咽喉 | 215篇 |
儿科学 | 529篇 |
妇产科学 | 387篇 |
基础医学 | 2563篇 |
口腔科学 | 937篇 |
临床医学 | 2038篇 |
内科学 | 3340篇 |
皮肤病学 | 365篇 |
神经病学 | 1600篇 |
特种医学 | 312篇 |
外科学 | 1441篇 |
综合类 | 157篇 |
一般理论 | 10篇 |
预防医学 | 2100篇 |
眼科学 | 300篇 |
药学 | 1191篇 |
中国医学 | 84篇 |
肿瘤学 | 1122篇 |
出版年
2024年 | 19篇 |
2023年 | 182篇 |
2022年 | 359篇 |
2021年 | 686篇 |
2020年 | 409篇 |
2019年 | 618篇 |
2018年 | 656篇 |
2017年 | 474篇 |
2016年 | 468篇 |
2015年 | 575篇 |
2014年 | 744篇 |
2013年 | 933篇 |
2012年 | 1476篇 |
2011年 | 1602篇 |
2010年 | 787篇 |
2009年 | 684篇 |
2008年 | 1181篇 |
2007年 | 1116篇 |
2006年 | 1052篇 |
2005年 | 951篇 |
2004年 | 811篇 |
2003年 | 787篇 |
2002年 | 747篇 |
2001年 | 124篇 |
2000年 | 94篇 |
1999年 | 82篇 |
1998年 | 140篇 |
1997年 | 89篇 |
1996年 | 78篇 |
1995年 | 61篇 |
1994年 | 63篇 |
1993年 | 59篇 |
1992年 | 41篇 |
1991年 | 49篇 |
1990年 | 45篇 |
1989年 | 27篇 |
1988年 | 22篇 |
1987年 | 28篇 |
1986年 | 33篇 |
1985年 | 30篇 |
1984年 | 30篇 |
1983年 | 31篇 |
1982年 | 29篇 |
1981年 | 28篇 |
1980年 | 28篇 |
1979年 | 21篇 |
1978年 | 10篇 |
1977年 | 13篇 |
1975年 | 12篇 |
1930年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Camilla Rodrigues de Almeida Ribeiro Katrini Guidolini Martinelli Vinícius da Motta de Mello Natlia Spitz Oscar Rafael Carmo Araújo Lia Laura Lewis-Ximenez Natalia Motta Araujo Vanessa Salete de Paula 《Viruses》2022,14(7)
Several hepatitis B virus (HBV)-related factors, including the viral load, genotype, and genomic mutations, have been linked to the development of liver diseases. Therefore, in this study we aimed to investigate the influence of HBV genetic variability during acute and chronic infection phases. A real-time nested PCR was used to detect HBV DNA in all samples (acute, n = 22; chronic, n = 49). All samples were sequenced for phylogenetic and mutation analyses. Genotype A, sub-genotype A1, was the most common genotype in the study population. A total of 190 mutations were found in the pre-S/S gene area and the acute profile revealed a greater number of nucleotide mutations (p < 0.05). However, both profiles contained nucleotide mutations linked to immune escape and an increased risk of hepatocellular carcinomas (acute, A7T; chronic, A7Q). Furthermore, 17 amino acid substitutions were identified in the viral polymerase region, including the drug resistance mutations lamivudine and entecavir (rtL180M), with statistically significant differences between the mutant and wild type strains. Owing to the natural occurrence of these mutations, it is important to screen for resistance mutations before beginning therapy. 相似文献
83.
Lisa Bastian Anumita Samanta Demetrius Ribeiro de Paula Frederik D. Weber Robby Schoenfeld Martin Dresler Lisa Genzel 《Human brain mapping》2022,43(13):3923
After experiences are encoded, post‐encoding reactivations during sleep have been proposed to mediate long‐term memory consolidation. Spindle–slow oscillation coupling during NREM sleep is a candidate mechanism through which a hippocampal‐cortical dialogue may strengthen a newly formed memory engram. Here, we investigated the role of fast spindle‐ and slow spindle–slow oscillation coupling in the consolidation of spatial memory in humans with a virtual watermaze task involving allocentric and egocentric learning strategies. Furthermore, we analyzed how resting‐state functional connectivity evolved across learning, consolidation, and retrieval of this task using a data‐driven approach. Our results show task‐related connectivity changes in the executive control network, the default mode network, and the hippocampal network at post‐task rest. The hippocampal network could further be divided into two subnetworks of which only one showed modulation by sleep. Decreased functional connectivity in this subnetwork was associated with higher spindle–slow oscillation coupling power, which was also related to better memory performance at test. Overall, this study contributes to a more holistic understanding of the functional resting‐state networks and the mechanisms during sleep associated to spatial memory consolidation. 相似文献
84.
The consumption of ultra-processed food (UPF)-rich diets represents a potential threat to human health. Considering maternal diet adequacy during pregnancy is a major determinant for perinatal health outcomes, this study aimed to systematically review and meta-analyze studies investigating the association between maternal consumption of a UPF-rich diet and perinatal outcomes. Conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, five electronic databases and gray literature using Google Scholar and ProQuest Dissertations and Theses Global were searched up to 31 May 2022. No restrictions were applied on language and publication date. Two reviewers independently conducted the study selection and data extraction process. Meta-analysis was conducted according to the random-effects model. In total, 61 studies were included in the systematic review and the overall population comprised 698,803 women from all gestational trimesters. Meta-analysis of cohort studies showed that maternal consumption of UPF-rich diets was associated with an increased risk of gestational diabetes mellitus (odds ratio (OR): 1.48; 95% confidence interval (CI): 1.17, 1.87) and preeclampsia (OR: 1.28; 95% CI: 1.15, 1.42). Neonatal outcomes showed no association. The overall GRADE quality of the evidence for the associations was very low. The findings highlight the need to monitor and reduce UPF consumption, specifically during the gestational period, as a strategy to prevent adverse perinatal outcomes. 相似文献
85.
Prada Diddier Baccarelli Andrea A. Terry Mary Beth Valdéz Leonora Cabrera Paula Just Allan Kloog Itai Caro Haydee García-Cuellar Claudia Sánchez-Pérez Yesennia Cruz Rodrigo Diaz-Chávez Jose Cortés Carlo Pérez Delia Meneses-García Abelardo Cantú-de-León David Herrera Luis A. Bargalló Enrique 《Breast cancer research and treatment》2021,187(2):525-533
Breast Cancer Research and Treatment - Many patients seek breast reconstruction following mastectomy. Debate exists regarding the best reconstructive option. The authors evaluate outcomes comparing... 相似文献
86.
87.
de Faria DE Borges LV Peters VM Reis JE Ribeiro LC de Cássia da Silveira E Sá R Guerra Mde O 《Phytotherapy research : PTR》2008,22(2):185-189
The Gingko biloba extract is contraindicated during pregnancy and lactation due to the lack of information about its effects on these reproductive phases. Previous studies have shown that G. biloba extract contains components with estrogenic and antiestrogenic activities, thus nursing dams treated with the extract of this plant could show reduction in milk production, resulting in malnutrition and poor development of pups. This work analyzes the postnatal development of pups, whose mothers were treated with G. biloba extract during the lactation period. Nursing Wistar rats received 3.5 mg/kg/day of G. biloba aqueous extract, corresponding to the highest human dose. Clinical signs of maternal toxicity were evaluated. The growth rate, viability, survival during treatment and lactation indices of the pups were calculated. The physical, motor and sensorial development of the pups was also evaluated. No maternal signs of toxicity were observed. As there were no biological differences between control and G. biloba treated pups, it is possible to assume that, in this experimental design, the administration of G. biloba aqueous extract to nursing rats during the lactation period seems to be devoid of toxic effect to mothers and to the physical, motor and sensory development of the pups. 相似文献
88.
BACKGROUND: Leptin is a key regulator of satiety; and the serum concentration is considered to reflect nutritional status. Expressed predominantly by the adipocytes, leptin is also expressed in placenta, which is a major source of both leptin and the leptin receptor in pregnancy serum. As a placenta protein, leptin serum concentrations may be perturbed in Down syndrome (DS) pregnancies as seen for pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotrophin-beta (hCGbeta). We examined whether leptin is a maternal serum marker for foetal DS in the first trimester. MATERIALS AND METHODS: Serum samples from 44 pregnant women with a DS foetus, and 135 control pregnant women in week 8 to 14 had the leptin concentration determined by immunoassay and the concentrations were converted into multiples of the median (MoM) of controls based on log-regression analysis. The distributions of log10 MoM leptin was compared in DS and control pregnancies. RESULTS: Serum leptin increased significantly with gestational age in controls (p = 0.02). The mean log10 MoM in controls was - 0.0486, with a median empirical MoM of 0.89, and - 0.0618, with a median empirical MoM of 0.80, in DS pregnancies. This difference was not significant. The log10 MoM leptin values in DS pregnancies did not change with gestational age (p = 0.32). CONCLUSION: Leptin is not a first-trimester marker for foetal DS. 相似文献
89.
90.
Dusse LM Carvalho Md Bragança WF Paiva SG Godoi LC Guimarães DA Fernandes AP 《European journal of obstetrics, gynecology, and reproductive biology》2007,134(1):20-23
OBJECTIVE: The aim of the present study was to compare the distribution of G1691A, G20210A and C677T mutations in pre-eclamptic Brazilian women and in matched control women with an uncomplicated normal pregnancy. STUDY DESIGN: these mutations were investigated by PCR-RFLP in 83 normal pregnancies (control group) and in 30 pre-eclamptic pregnant women (severe form). RESULTS: G1691A mutation was detected neither in the control group nor in pre-eclamsia women. G20210A mutation was detected in heterozygosis in 3 (3.61%) control subjects, but not in pre-eclampsia group. C677T mutation was detected in homozygosis in 6 (7.23%) control subjects and 2 (6.67%) pre-eclamptic women and in heterozygosis in 31 (37.3%) control subjects and 12 (40%) pre-eclamptic women. Differences in the mutation frequencies detected in the two groups were not statistically significant. CONCLUSION: No correlation was observed between pre-eclampsia and presence of G1691A, G20210A and C677T mutations in Brazilian women. 相似文献