全文获取类型
收费全文 | 27983篇 |
免费 | 1998篇 |
国内免费 | 90篇 |
专业分类
耳鼻咽喉 | 264篇 |
儿科学 | 797篇 |
妇产科学 | 709篇 |
基础医学 | 4092篇 |
口腔科学 | 1114篇 |
临床医学 | 3012篇 |
内科学 | 5549篇 |
皮肤病学 | 600篇 |
神经病学 | 2614篇 |
特种医学 | 820篇 |
外科学 | 2859篇 |
综合类 | 249篇 |
现状与发展 | 1篇 |
一般理论 | 26篇 |
预防医学 | 3044篇 |
眼科学 | 442篇 |
药学 | 2132篇 |
中国医学 | 133篇 |
肿瘤学 | 1614篇 |
出版年
2023年 | 344篇 |
2022年 | 554篇 |
2021年 | 986篇 |
2020年 | 664篇 |
2019年 | 1021篇 |
2018年 | 1056篇 |
2017年 | 812篇 |
2016年 | 832篇 |
2015年 | 903篇 |
2014年 | 1193篇 |
2013年 | 1502篇 |
2012年 | 2380篇 |
2011年 | 2304篇 |
2010年 | 1176篇 |
2009年 | 1079篇 |
2008年 | 1782篇 |
2007年 | 1773篇 |
2006年 | 1495篇 |
2005年 | 1504篇 |
2004年 | 1270篇 |
2003年 | 1105篇 |
2002年 | 1035篇 |
2001年 | 304篇 |
2000年 | 245篇 |
1999年 | 289篇 |
1998年 | 180篇 |
1997年 | 161篇 |
1996年 | 100篇 |
1995年 | 107篇 |
1994年 | 93篇 |
1993年 | 88篇 |
1992年 | 130篇 |
1991年 | 110篇 |
1990年 | 120篇 |
1989年 | 101篇 |
1988年 | 109篇 |
1987年 | 103篇 |
1986年 | 88篇 |
1985年 | 89篇 |
1984年 | 65篇 |
1983年 | 53篇 |
1982年 | 59篇 |
1981年 | 49篇 |
1980年 | 44篇 |
1979年 | 70篇 |
1977年 | 35篇 |
1975年 | 39篇 |
1974年 | 48篇 |
1973年 | 50篇 |
1970年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Adilson Cunha Ferreira Edward Araujo Júnior Wellington P. Martins João Francisco Jordão Antônio Hélio Oliani Simon E. Meagher 《The journal of maternal-fetal & neonatal medicine》2015,28(14):1706-1710
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality. 相似文献
2.
Mariana Spitz Alexandre Aluízio Costa Machado Rodrigo do Carmo Carvalho Fernanda Martins Maia Monica Santoro Haddad Dagoberto Calegaro Milberto Scaff Egberto Reis Barbosa 《Movement disorders》2006,21(9):1520-1522
We report on 3 patients with pseudoathetosis, which are involuntary, slow, writhing movements due to loss of proprioception. 相似文献
3.
Caroline A. Harrison BMedSci MRCS ; Martin J. Heaton MD FRCS ; Christopher M. Layton PhD ; Sheila Mac Neil PhD 《Wound repair and regeneration》2006,14(2):203-209
To produce a stable epidermis, keratinocytes need to be firmly attached to the basement membrane. However, following wounding, keratinocytes are required to develop a migratory phenotype in order to reepithelialize the wound. To investigate some of the issues underlying reepithelialization, we have developed a three-dimensional in vitro model of tissue-engineered skin, comprising sterilized human dermis seeded with human keratinocytes and dermal fibroblasts. Using this model, we have shown that the inclusion of fibroblasts within the model increases the stability of keratinocyte attachment. We have also demonstrated that keratinocyte migration occurs most effectively in the absence of a basement membrane and following the inclusion of fibroblasts in the model. In addition, subjecting the keratinocyte layer to mechanical trauma induces a migratory phenotype. We conclude that this three-dimensional in vitro wound model can be used to increase our understanding of the factors that enhance keratinocyte migration and hence wound healing in vivo. 相似文献
4.
Human and mouse genomes contain more than 20 related genes encoding diverse type I interferons (IFNs- alpha/beta), cytokines that are crucial for resistance of organisms against viral infections. Although the amino acid sequences of various IFN-alpha/beta subtypes differ markedly, they are all considered to share a common three-dimensional structure and to bind the same heterodimeric receptor, composed of the IFNAR-1 and IFNAR-2 subunits. Analysis of available mammalian IFN-beta sequences showed that they all carry 1 to 5 predicted N-glycosylation sites. Murine IFN-beta contains three predicted N-glycosylation sites (Asn29, Asn69, Asn76), one of which (Asn29) is located in the AB loop, in a region predicted to interact with the type I IFN receptor. The aim of this work was to test if this site is indeed N-glycosylated and if this glycosylation would affect IFN antiviral activity. We showed that all three N-glycosylation sites predicted from the sequence, including Asn29, carry N-linked sugars. Mutation of individual N-glycosylation sites had a weak negative influence on IFN antiviral activity. In contrast, the complete loss of glycosylation dramatically decreased activity. Our data suggest that interaction of murine IFN-beta with the IFNAR could locally differ from that of human IFN-alpha2 and human IFN-beta. 相似文献
5.
Prostatitis and male infertility are frequent disorders, and the role of prostatitis in male infertility has been under discussion for more than 30 years. Many researchers have shown relevant links between the two. Although a causal relationship has not been definitely demonstrated, increasing evidence shows that chronic prostatitis has a relevant negative impact on male fertility potential, at least in certain subgroups. In the following review, we focus on the present state of knowledge on the role of chronic prostatitis as an etiologic factor in male infertility. 相似文献
6.
7.
8.
D. Caroline Blanchard Jon K. Shepherd Antonio De Padua Carobrez Robert J. Blanchard 《Neuroscience and biobehavioral reviews》1991,15(4):461-468
Female rats consistently show a pattern of differences in defensive behaviors compared to males which parallel the effects of exposure to a nonpainful threat stimulus (cat or cat odor) in the same tests and measures. These indications of greater defensiveness for females are particularly common in situations involving potential, as opposed to actual and present, threat, a factor which probably also reflects ceiling or floor effects in situations involving very intense defensiveness. In addition, pharmacological studies indicate sex differences in the effects of selective serotonin (5-HT) receptor agonists and antagonists on defensive responding. These findings indicate that sex effects must be considered in studies of the pharmacological control of defensive behaviors, and suggest that responsivity to sex effects may be an additional criterion for the suitability of animal models of anxiety. 相似文献
9.
A patient with Hodgkin’s disease received a fractionated 3, 740 rad dosage over 4 weeks to a portal that included both kidneys. Three months later a computed tomographic scan obtained 2 hours after intravenous contrast injection demonstrated sharply demarcated, dense, persistent nephrograms corresponding to the irradiated areas. These changes are ascribed to acute radiation nephritis, reflecting tubular stasis and ischemia. 相似文献
10.
Betsy D. Kennard Susan G. Silva Simon Tonev Paul Rohde Jennifer L. Hughes Benedetto Vitiello Christopher J. Kratochvil John F. Curry Graham J. Emslie Mark Reinecke John March 《Journal of the American Academy of Child and Adolescent Psychiatry》2009,48(2):186-195
ObjectiveWe examine remission rate probabilities, recovery rates, and residual symptoms across 36 weeks in the Treatment for Adolescents with Depression Study (TADS).MethodThe TADS, a multisite clinical trial, randomized 439 adolescents with major depressive disorder to 12 weeks of treatment with fluoxetine, cognitive–behavioral therapy, their combination, or pill placebo. The pill placebo group, treated openly after week 12, was not included in the subsequent analyses. Treatment differences in remission rates and probabilities of remission over time are compared. Recovery rates in remitters at weeks 12 (acute phase remitters) and 18 (continuation phase remitters) are summarized. We also examined whether residual symptoms at the end of 12 weeks of acute treatment predicted later remission.ResultsAt week 36, the estimated remission rates for intention-to-treat cases were as follows: combination, 60%; fluoxetine, 55%; cognitive–behavioral therapy, 64%; and overall, 60%. Paired comparisons reveal that, at week 24, all active treatments converge on remission outcomes. The recovery rate at week 36 was 65% for acute phase remitters and 71% for continuation phase remitters, with no significant between-treatment differences in recovery rates. Residual symptoms at the end of acute treatment predicted failure to achieve remission at weeks 18 and 36.ConclusionsMost depressed adolescents in all three treatment modalities achieved remission at the end of 9 months of treatment. 相似文献