全文获取类型
收费全文 | 8865篇 |
免费 | 527篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 189篇 |
妇产科学 | 146篇 |
基础医学 | 1157篇 |
口腔科学 | 179篇 |
临床医学 | 900篇 |
内科学 | 2086篇 |
皮肤病学 | 222篇 |
神经病学 | 762篇 |
特种医学 | 385篇 |
外科学 | 1310篇 |
综合类 | 15篇 |
一般理论 | 3篇 |
预防医学 | 706篇 |
眼科学 | 69篇 |
药学 | 576篇 |
中国医学 | 41篇 |
肿瘤学 | 640篇 |
出版年
2024年 | 6篇 |
2023年 | 41篇 |
2022年 | 74篇 |
2021年 | 177篇 |
2020年 | 135篇 |
2019年 | 233篇 |
2018年 | 277篇 |
2017年 | 159篇 |
2016年 | 203篇 |
2015年 | 227篇 |
2014年 | 359篇 |
2013年 | 495篇 |
2012年 | 677篇 |
2011年 | 731篇 |
2010年 | 415篇 |
2009年 | 371篇 |
2008年 | 584篇 |
2007年 | 685篇 |
2006年 | 604篇 |
2005年 | 585篇 |
2004年 | 585篇 |
2003年 | 507篇 |
2002年 | 467篇 |
2001年 | 74篇 |
2000年 | 67篇 |
1999年 | 80篇 |
1998年 | 91篇 |
1997年 | 71篇 |
1996年 | 65篇 |
1995年 | 54篇 |
1994年 | 45篇 |
1993年 | 42篇 |
1992年 | 16篇 |
1991年 | 43篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 20篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 21篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1972年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有9450条查询结果,搜索用时 15 毫秒
61.
van Roekel E Goossens L Scholte RH Engels RC Verhagen M 《Journal of child psychology and psychiatry, and allied disciplines》2011,52(10):1044-1051
Background: Loneliness is a common problem in adolescence. Earlier research focused on genes within the serotonin and oxytocin systems, but no studies have examined the role of dopamine‐related genes in loneliness. In the present study, we focused on the dopamine D2 receptor gene (DRD2). Methods: Associations among the DRD2, sex, parental support, and loneliness were examined in a longitudinal study spanning five annual waves (N = 307). Results: Using Latent Growth Curve Modeling, DRD2 genotype was not directly related to loneliness. Interactions were found between parental support and DRD2 genotype, showing that adolescents with the A2A2 genotype who perceived little support from their parents had the highest baseline levels of loneliness. Adolescents with an A1 allele were not susceptible to the rewarding effect of parental support. Conclusions: The present study is the first to examine the role of the DRD2 genotype in loneliness. Our results contribute to a further understanding of the environmental and genetic basis of loneliness in adolescence. 相似文献
62.
HPV circulating tumor DNA to monitor the efficacy of anti‐PD‐1 therapy in metastatic squamous cell carcinoma of the anal canal: A case report 下载免费PDF全文
Luc Cabel François‐Clément Bidard Vincent Servois Wulfran Cacheux Pascale Mariani Emanuela Romano Mathieu Minsat Ivan Bieche Fereshteh Farkhondeh Emmanuelle Jeannot Bruno Buecher 《International journal of cancer. Journal international du cancer》2017,141(8):1667-1670
Squamous cell carcinoma of the anal canal (SCCA) is a rare HPV‐associated cancer with limited sensitivity to standard chemotherapy. In a phase 2 study, nivolumab, an anti PD‐1 immune checkpoint inhibitor, demonstrated significant efficacy as single‐agent therapy in metastatic SCCA patients. Nevertheless, imaging assessment by standard RECIST criteria of the efficacy of immune therapy can be difficult in some patients due to tumor immune cell infiltration, and biomarkers of treatment efficacy are needed. We have previously developed a quantitative droplet digital PCR (ddPCR) technique to detect HPV circulating tumor DNA (HPV ctDNA), with excellent sensitivity and specificity. Here, we report, for the first time, the kinetics of HPV ctDNA during therapy in a patient with metastatic SCCA, who obtained sustained partial response to single‐agent nivolumab. We observed an early and very significant decrease of HPV ctDNA during therapy from the baseline level of 3713 copies/ml plasma to 564 copies/ml plasma at 4 weeks, and 156 copies/ml at 6 weeks, followed by a plateau. This observation provides proof‐of‐concept that HPV ctDNA can be used as a noninvasive early dynamic biomarker to monitor the efficacy of new immunotherapy agents. 相似文献
63.
The aim of this study was to evaluate the effect of selective feticide (SF) compared to expectant management (EM) on perinatal outcome in dichorionic and monochorionic twins discordant for anencephaly. For this purpose, we conducted a systematic review of literature and added ten unpublished cases. As a result, we found that in dichorionic twins, mean gestational age (GA) at birth in the SF group was 38.0 weeks versus 34.9 weeks (P = 0.0002). Mean birth weight was 2922 g in the SF group versus 2474 g (P = 0.03). In monochorionic twins, mean GA at birth was 35.2 weeks versus 32.7 weeks (P = 0.1). Mean birth weight was 2711 g versus 1667 g (P = 0.0001).We conclude that while SF does not reduce perinatal mortality, it does result in significantly longer gestations and higher birth weight, and appears to be the management of choice in dichorionic twins discordant for anencephaly. In monochorionic twins, SF also increases birth weight, but in view of the complexity of this group, no clear recommendations can be made. 相似文献
64.
Muris C Girard B Creveuil C Durin L Herlicoviez M Dreyfus M 《European journal of obstetrics, gynecology, and reproductive biology》2007,131(2):163-168
OBJECTIVES: The aim of our study was to define the benefits and risks related to expectant management in the midtrimester rupture of membranes and to assess the prognostic factors in order to give objective informations to parents facing these obstetrical situations. STUDY DESIGN: We conducted a retrospective study. The study population included 49 patients with premature rupture of membranes at 16-23 weeks' gestation during the period January 1998-June 2003. The main criterion for judgement was neonate survival. Statistical analysis included chi2-test for the qualitative variables and Student's test for the quantitative variables. The threshold for significance was 5%. RESULTS: Twenty couples out of 49 chose medical termination of pregnancy. Among the 29 other pregnancies, the mean latency period was 2.1 weeks. The mean gestational age at delivery was 23.2 weeks. Nineteen patients were delivered after 22 weeks. The main prognostic factors were the initial amniotic fluid index (2.9 cm versus 0.8 cm) (p=0.042) and gestational age at delivery (26.7 weeks versus 22.6 weeks) (p<0.001). About 2% of the pregnancies were complicated by maternal infection. Eighty-three percent of the survivors had neonatal respiratory distress syndrome. 41.2% of them presented sepsis. We observed no cases of severe intraventricular haemorrhage. The number of infants born after 24 weeks of gestation and still alive at 1 week was 12, representing 24% of pregnancies and 63% of the infants born after 24 weeks. CONCLUSION: Expectant management can be widely suggested to patients. However, termination of pregnancy is acceptable, in cases with a poor prognosis including anamnios and premature rupture of membranes before 21 weeks. 相似文献
65.
Ravel C Letur H Le Lannou D Barthélémy C Bresson JL Siffroi JP;Genetics Commission of the French Federation of CECOS 《Fertility and sterility》2007,87(2):439-441
Oocyte donors are chosen among phenotypically normal and fertile women who are not expected to carry any chromosomal abnormality. A high incidence of balanced structural chromosomal rearrangements has been found within oocyte donors. This result raises the question of a possible bias in their recruitment with respect to their familial background and/or personal reproductive history. 相似文献
66.
67.
Zengfeng Zhao Jianzhuang Xiao Denis Damidot Sbastien Rmond David Bulteel Luc Courard 《Materials》2022,15(9)
Adherent hardened cement paste attached to recycled concrete aggregates (RCA) generally presents a higher porosity than natural aggregates, which induces a lower porosity in the properties of RCA. The characterization of the adherent hardened cement paste content (HCPC) in the fine RCA would promote better applications of RCA in concrete, but the determination of HCPC in fine RCA is not well established. A simple method based on salicylic acid dissolution was specifically developed to quantify the HCPC in RCA, especially for RCA containing limestone aggregates. The results demonstrated that the soluble fraction in salicylic acid (SFSA) was equal to the HCPC for white cement and slightly lower for grey Portland cement, which was also confirmed by a theoretical approach using modelling the hydration of cement paste with the chemical equations and the stoichiometric ratios. The physical and mechanical properties of RCA (e.g., water absorption) were strongly correlated to the SFSA. For industrial RCA, SFSA did not give the exact value of HCPC, but it was sufficient to correlate HCPC with the other properties of RCA. The water absorption could be estimated with good accuracy for very fine RCA (laboratory-manufactured RCA or industrial RCA) by extrapolating the relationship between water absorption and HCPC, which is very important for concrete formulation. 相似文献
68.
69.