全文获取类型
收费全文 | 8257篇 |
免费 | 457篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 59篇 |
儿科学 | 229篇 |
妇产科学 | 196篇 |
基础医学 | 1145篇 |
口腔科学 | 148篇 |
临床医学 | 744篇 |
内科学 | 2093篇 |
皮肤病学 | 226篇 |
神经病学 | 639篇 |
特种医学 | 156篇 |
外科学 | 899篇 |
综合类 | 21篇 |
预防医学 | 888篇 |
眼科学 | 90篇 |
药学 | 555篇 |
中国医学 | 27篇 |
肿瘤学 | 636篇 |
出版年
2023年 | 57篇 |
2022年 | 134篇 |
2021年 | 283篇 |
2020年 | 132篇 |
2019年 | 283篇 |
2018年 | 318篇 |
2017年 | 157篇 |
2016年 | 183篇 |
2015年 | 198篇 |
2014年 | 333篇 |
2013年 | 409篇 |
2012年 | 624篇 |
2011年 | 728篇 |
2010年 | 368篇 |
2009年 | 337篇 |
2008年 | 543篇 |
2007年 | 531篇 |
2006年 | 474篇 |
2005年 | 513篇 |
2004年 | 381篇 |
2003年 | 404篇 |
2002年 | 304篇 |
2001年 | 102篇 |
2000年 | 96篇 |
1999年 | 106篇 |
1998年 | 69篇 |
1997年 | 70篇 |
1996年 | 43篇 |
1995年 | 53篇 |
1994年 | 32篇 |
1993年 | 35篇 |
1992年 | 50篇 |
1991年 | 43篇 |
1990年 | 48篇 |
1989年 | 47篇 |
1988年 | 38篇 |
1987年 | 26篇 |
1986年 | 27篇 |
1985年 | 21篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1973年 | 7篇 |
1971年 | 6篇 |
1969年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有8751条查询结果,搜索用时 31 毫秒
71.
72.
73.
Differential neuronal survival in the avian ciliary ganglion after chronic acetylcholine receptor blockade 总被引:2,自引:0,他引:2
We have described in the preceding 2 papers the development of the pharmacological and contractile properties of all targets of the ciliary ganglion: the iris and ciliary body (Pilar et al., 1987), and the choroidal coat (Meriney and Pilar, 1987). In this paper, we examine the chronic effects of ACh receptor (AChR) blockade on ciliary ganglion neuron survival. Nicotinic or muscarinic AChR blockers were administered daily to developing chicken embryos during the normal neuronal death period in the ciliary ganglion. The effects of the blockers on ganglionic and neuromuscular transmission were assessed, and neuronal survival was assayed by counting both the total number of ganglion neurons and the selectively HRP-labeled ciliary neurons after the normal neuronal death period. Blockade of ganglionic transmission decreases survival in both populations of neurons. Blockade of neuromuscular muscular transmission increases survival in the ciliary population, which innervates the striated iris and ciliary body muscle. In contrast, blockade of synaptic activity has various influences on the survival of the choroid population, which innervates the smooth muscle of the choroid coat. Smooth muscle muscarinic receptor blockade with atropine does not influence survival. At higher doses (which block ganglionic transmission), atropine decreases choroid survival. Survival of the choroid population is increased by nicotinic blockade with 75 micrograms alpha bungarotoxin (alpha BTX), but decreased by 12.5 micrograms alpha BTX. Two main conclusions arise from these studies. Activation of postsynaptic AChRs in both the ganglion and the periphery are important in the regulation of neuronal survival. These effects usually occur in opposite directions: Blockade of ganglionic transmission decreases neuronal survival, while paralysis of neuromuscular transmission increases neuronal survival. This embodies the "balance" hypothesis (Cunningham, 1982) for neuronal survival, which states that motoneurons must balance afferent and target interactions during a critical period after synapses are formed in both regions. The present observations support this hypothesis. However, although both ciliary and choroid neurons have been shown to depend on the presence of the periphery for survival, target muscle paralysis via AChR blockade rescues the ciliary neurons but does not influence survival in the choroid population. Target-dependent regulation of choroid neuron survival during the normal neuronal death period is clearly different from the regulation of ciliary neuron survival. 相似文献
74.
Rosa M. García-García María Arias-lvarez Pilar Milln María Rodríguez Ana Snchez-Rodríguez Pedro L. Lorenzo Pilar G. Rebollar 《Nutrients》2021,13(2)
Nutritional status during gestation can influence mother and offspring metabolism. Undernutrition in pregnancy affects women in both western and developing countries, and it is associated with a high prevalence of chronic diseases in later life. The present work was conducted in the rabbit model, as a longitudinal study, to examine the effect of food restriction during early and mid-gestation, and re-feeding ad libitum until the end of pregnancy on metabolic status and body reserves of mother and, its association with development and metabolism of fetuses and female offspring to the juvenile stage. Little changes in live body weight (LBW), compensatory feed intake, similar body reserves, and metabolism were observed in dams. Placenta biometry and efficiency were slightly affected, but fetal BW and phenotype were not modified. However, hyperinsulinemia, insulin resistance, and hypertriglyceridemia were demonstrated in pre-term fetuses. In the juvenile period, these changes were not evidenced, and a similar pattern of growth and serum metabolic parameters in offspring of food-restricted mothers were found, except in serum aminotransferases levels, which increased. These were associated with higher liver fibrosis. Maternal food restriction in the early and mid-pregnancy followed by re-feeding in our rabbit model established a compensatory energy status in dams and alleviated potential long-term consequences in growth and metabolism in the offspring, even if fetal metabolism was altered. 相似文献
75.
76.
Alfredo García-Layana Sergio Recalde Maria Hernandez Maximino J. Abraldes Joo Nascimento Emiliano Hernndez-Galilea Begoa Olmedilla-Alonso Jose Juan Escobar-Barranco Miguel Angel Zapata Rufino Silva Mariana Caballero Arredondo María Carmen Lopez-Sabater Silvia Mendez-Martínez Nieves Pardias-Barn Pilar Calvo Patricia Fernndez-Robredo 《Nutrients》2021,13(4)
The purpose of this study is evaluate the efficacy and safety of medicinal products containing the original Age-Related Eye Disease group (AREDS) formulation at doses approved in Europe (EU, control group; n = 59) with a product that adds DHA, lutein, zeaxanthin, resveratrol and hydroxytyrosol to the formula (intervention group; n = 50). This was a multicenter, randomized, observer-blinded trial conducted in patients aged 50 years or older diagnosed with unilateral exudative Age related Macular Degeneration AMD. At month 12, the intervention did not have a significant differential effect on visual acuity compared with the control group, with an estimated treatment difference in Early Treatment Diabetic Retinopathy Study (ETDRS) of −1.63 (95% CI −0.83 to 4.09; p = 0.192). The intervention exhibited a significant and, in most cases, relevant effect in terms of a reduction in some inflammatory cytokines and a greater improvement in the fatty acid profile and serum lutein and zeaxantin concentration. In patients with unilateral wet AMD, the addition of lutein, zeaxanthin, resveratrol, hydroxytyrosol and DHA to the AREDS EU recommended doses in the short-term did not have a differential effect on visual acuity compared to a standard AREDS EU formula but, in addition to improving the fatty acid profile and increasing carotenoid serum levels, may provide a beneficial effect in improving the proinflammatory and proangiogenic profile of patients with AMD. 相似文献
77.
Lorena Villalba-Heredia Cristina Comeras-Chueca Alejandro Gonzlez-Agüero Daniel Domingo-del-Val Pilar Calmarza Germn Vicente-Rodríguez Jos A. Casajús ngel Matute-Llorente 《Nutrients》2021,13(5)
Childhood obesity has become a major global health problem. Vitamin D deficiency and poor cardiorespiratory fitness are highly prevalent in children with overweight or obesity, but little is known about their relationships. In this study, we aimed to analyze the relationship between serum 25-hydroxyvitamin D (25(OH)D) and cardiorespiratory fitness parameters in prepubertal obese and overweight children. A cross-sectional design with a sample of 57 prepubertal children, aged 9–11 years, with overweight or obesity was used. The fasting concentration of 25(OH)D was analyzed with a chemiluminescent microparticle immunoassay. Fat and lean body masses were determined by using DXA. Maximal oxygen uptake (VO2max) was measured with the maximal treadmill test. A total of 68.4% of the sample had sufficient levels of 25(OH)D. As expected, their cardiorespiratory fitness was poor compared with that of normal-weight children, but 60% of the group exceeded the median obesity-specific reference values. No differences were found between the sexes for relative VO2max or 25(OH)D levels. Moreover, no correlations were found between 25(OH)D and body composition or cardiorespiratory parameters for sex or vitamin D groups. Vitamin D status seems not to be directly related to body composition or cardiorespiratory fitness in prepubertal overweight or obese children. 相似文献
78.
Cobb Cory L. Salas-Wright Christopher P. John Rachel Schwartz Seth J. Vaughn Michael Martínez Charles R. Awad Germine Pinedo Miguel Cano Miguel Ángel 《Prevention science》2021,22(3):397-407
Prevention Science - We examined national trends and mental health correlates of discrimination among Latinos in the USA. We used data from two nationally representative surveys based on the... 相似文献
79.
Alba Manuel-Vázquez José Ramón Oliver-Guillén Raquel Latorre-Fragua Ana Palomares Cano Mario Serradilla Martín José Manuel Ramia 《Cirugía espa?ola》2021,99(2):124-131
IntroductionThe number of citations is considered as an indirect indicator of the merit of an article, journal or researcher, although it is not an infallible method to determine scientific quality. Our goal is to determine the characteristics of the articles most cited about pancreas and laparoscopy.MethodsWe performed a search of all articles published in any journal about pancreas and laparoscopy until September 2019 and selected the 100 most cited papers. We recorded number of citations, journal, year of publication, quartil, impact factor, institution, country, authors type of paper, type of surgery, topic and area.ResultsThe top 100 citations account 10,970 citations in total. The journal with the most articles is Surgical Endoscopy and 2007 is the year with the highest number of articles in the top 100 citations. The percentage of publications from America and Europe are similar.Case series is the most frequently paper, outcomes/morbidity is the most frequently discussed topic, and distal pancreatectomy is the most frequently type of surgery.ConclusionsThis bibliometric study on pancreas and laparoscopy is conditioned by the time factor, since laparoscopy has arrived later at pancreatic surgery, probably due to the morbidity and mortality associated with pancreatic surgery and the need for a high specialization in this field. The literature is recent and scarce. More and better-quality studies are needed in this field. 相似文献