全文获取类型
收费全文 | 2088篇 |
免费 | 124篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 144篇 |
妇产科学 | 95篇 |
基础医学 | 225篇 |
口腔科学 | 67篇 |
临床医学 | 196篇 |
内科学 | 520篇 |
皮肤病学 | 24篇 |
神经病学 | 157篇 |
特种医学 | 149篇 |
外科学 | 235篇 |
综合类 | 13篇 |
一般理论 | 1篇 |
预防医学 | 150篇 |
眼科学 | 23篇 |
药学 | 141篇 |
中国医学 | 3篇 |
肿瘤学 | 83篇 |
出版年
2022年 | 16篇 |
2021年 | 38篇 |
2020年 | 32篇 |
2019年 | 39篇 |
2018年 | 54篇 |
2017年 | 35篇 |
2016年 | 41篇 |
2015年 | 43篇 |
2014年 | 38篇 |
2013年 | 76篇 |
2012年 | 108篇 |
2011年 | 131篇 |
2010年 | 81篇 |
2009年 | 64篇 |
2008年 | 114篇 |
2007年 | 121篇 |
2006年 | 88篇 |
2005年 | 86篇 |
2004年 | 64篇 |
2003年 | 63篇 |
2002年 | 55篇 |
2001年 | 63篇 |
2000年 | 47篇 |
1999年 | 39篇 |
1998年 | 53篇 |
1997年 | 57篇 |
1996年 | 58篇 |
1995年 | 48篇 |
1994年 | 37篇 |
1993年 | 39篇 |
1992年 | 29篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 34篇 |
1988年 | 31篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 26篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 9篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 16篇 |
1976年 | 15篇 |
1975年 | 12篇 |
1974年 | 9篇 |
1970年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有2241条查询结果,搜索用时 13 毫秒
51.
In vivo fragmentation of heparan sulfate by heparanase overexpression renders mice resistant to amyloid protein A amyloidosis
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Li JP Galvis ML Gong F Zhang X Zcharia E Metzger S Vlodavsky I Kisilevsky R Lindahl U 《Proceedings of the National Academy of Sciences of the United States of America》2005,102(18):6473-6477
Amyloid diseases encompass >20 medical disorders that include amyloid protein A (AA) amyloidosis, Alzheimer's disease, and type 2 diabetes. A common feature of these conditions is the selective organ deposition of disease-specific fibrillar proteins, along with the sulfated glycosaminoglycan, heparan sulfate. We have generated transgenic mice that overexpress human heparanase and have tested their susceptibility to amyloid induction. Drastic shortening of heparan sulfate chains was observed in heparanase-overproducing organs, such as liver and kidney. These sites selectively escaped amyloid deposition on experimental induction of inflammation-associated AA amyloidosis, as verified by lack of material staining with Congo Red, as well as lack of associated polysaccharide, whereas the same tissues from control animals were heavily infiltrated with amyloid. By contrast, the spleens of transgenic mice that failed to significantly overexpress heparanase contained heparan sulfate chains similar in size to those of control spleen and remained susceptible to amyloid deposition. Our findings provide direct in vivo evidence that heparan sulfate is essential for the development of amyloid disease. 相似文献
52.
Eosinophil autofluorescence and its use in isolation and analysis of human eosinophils using flow microfluorometry 总被引:5,自引:1,他引:5
Unstained human eosinophils exhibit unusually bright autofluorescence, which allows them to be distinguished from other leukocytes using fluorescence microscopy. Eosinophil fluorescence is associated with the cytoplasmic granules of the cells. Eosinophil granule extracts, containing an as-yet-undefined eosinophil fluorescence factor, exhibited excitation maxima at 370 nm and 450 nm, with maximum emission at 520 nm. Eosinophils adhering to opsonized parasites in vitro deposit fluorescent material onto the parasite surface. Eosinophil fluorescence was of sufficient intensity to allow the preparation of viable, highly enriched (greater than or equal to 98%), eosinophil suspensions from peripheral blood of normal and eosinophilic donors using a fluorescence- activated cell sorter. Quantitative studies of eosinophil autofluorescence were performed using flow microfluorometry. Fluorescence intensity of blood eosinophils from normal volunteers and eosinophilic patients varied inversely with the log of the donor's absolute eosinophil count regardless of clinical diagnosis. 相似文献
53.
Carlos Escobar Julio Martí-Almor Alejandro Pérez Cabeza M. José Martínez-Zapata 《Revista espa?ola de cardiología》2019,72(4):305-316
Introduction and objectives
To assess the effectiveness of direct oral anticoagulants vs vitamin K antagonists in real-life patients with atrial fibrillation.Methods
A systematic review was performed according to Cochrane methodological standards. The results were reported according to the PRISMA statement. The ROBINS-I tool was used to assess risk of bias.Results
A total of 27 different studies publishing data in 30 publications were included. In the studies with a follow-up up to 1 year, apixaban (HR, 0.93; 95%CI, 0.71-1.20) and dabigatran (HR, 0.95; 95%CI, 0.80-1.13) did not significantly reduce the risk of ischemic stroke vs warfarin, whereas rivaroxaban significantly reduced this risk (HR, 0.83; 95%CI, 0.73-0.94). Apixaban (HR, 0.66; 95%CI, 0.55-0.80) and dabigatran (HR, 0.83; 95%CI, 0.70-0.97) significantly reduced the major bleeding risk vs warfarin, but not rivaroxaban (HR, 1.02; 95%CI, 0.95-1.10), although with a high statistical heterogeneity among studies. Apixaban (HR, 0.56; 95%CI, 0.42-0.73), dabigatran (HR, 0.45; 95%CI, 0.39-0.51), and rivaroxaban (HR, 0.66; 95%CI, 0.49-0.88) significantly reduced the risk of intracranial bleeding vs warfarin. Reduced doses of direct oral anticoagulants were associated with a slightly better safety profile, but with a marked reduction in stroke prevention effectiveness.Conclusions
Data from this meta-analysis suggest that, vs warfarin, the stroke prevention effectiveness and bleeding risk of direct oral anticoagulants may differ in real-life patients with atrial fibrillation. 相似文献54.
Rationale,design and preliminary results of the GALIPEMIAS study (prevalence and lipid control of familial dyslipidemia in Galicia,northwest Spain)
下载免费PDF全文
![点击此处可从《International journal of clinical practice》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rosa María Argüeso‐Armesto Teresa‐Rosalia Pérez‐Castro José Luis Díaz‐Díaz Avelino Rodríguez‐González María Eugenia Ameneiros‐Lago Alberto del Alamo‐Alonso José Manuel de Toro‐Santos Pablo Ángel Fernández‐Catalina Marta Pena‐Seijo Jose Antonio Díaz‐Peromingo Antonio Pose‐Reino Carlos Alberto Názara‐Otero María Rosa Vázquez‐Freire Lisett Escobar‐Seoane Pedro Gordo‐Fraile María del Mar Castellanos‐Rodríguez José Ángel Rodríguez‐Fernández Javier Muñiz 《International journal of clinical practice》2018,72(9)
55.
Pedro?Gullón Hannah?M.?Badland Silvia?Alfayate Usama?Bilal Francisco?Escobar Alba?Cebrecos Julia?Diez Manuel?FrancoEmail author 《Journal of urban health》2015,92(5):923-939
Audit tools are useful for exploring the urban environment and its association with physical activity. Virtual auditing options are becoming increasingly available potentially reducing the resources needed to conduct these assessments. Only a few studies have explored the use of virtual audit tools. Our objective is to test if the Madrid Systematic Pedestrian and Cycling Environment Scan (M-SPACES) discriminates between areas with different urban forms and to validate virtual street auditing using M-SPACES. Three areas (N?=?500 street segments) were selected for variation in population density. M-SPACES was used to audit street segments physically and virtually (Google Street View) by two researchers in 2013–2014. For both physical and virtual audits, all analyzed features score significantly different by area (p?<?0.05). Most of the features showed substantial (ICC?=?0.6–0.8) or almost perfect (ICC?≥?0.8) agreement between virtual and physical audits, especially neighborhood permeability walking infrastructure, traffic safety, streetscape aesthetics, and destinations. Intra-rater agreement was generally acceptable (ICC?>?0.6). Inter-rater agreement was generally poor (ICC?<?0.4). Virtual auditing provides a valid and feasible way of measuring residential urban environments. Comprehensive auditor training may be needed to guarantee good inter-rater agreement. 相似文献
56.
Ellen L. Vaughan Tiffany K. Chang Oscar S. Escobar Marcel A. de Dios 《Substance Abuse》2015,36(3):314-317
Background: Hispanic college students represent a growing proportion of the college population. Studies have found that an individual's perception of the drinking of others is linked to one's own personal use and that college students frequently overestimate the drinking of their peers. The current study builds on previous college student drinking literature by examining the influence that attending a Hispanic-serving institution (HSI) has on the personal alcohol use and perception of peers’ drinking norms among Hispanic college students. Methods: This secondary data analysis utilized data from the American College Health Association's National College Health Assessment. Participants were self-identified Hispanics between the ages of 18 and 25 (N = 4336). Results: Results indicated that there was a significant interaction between attending an HSI and the perception of the number of drinks of a typical student. Specifically, the perception of others’ drinking was more strongly linked to personal drinking for students in non-Hispanic serving institutions. Conclusions: The protective effect of attending a Hispanic-serving institution may be related to a more culturally affirming college environment. 相似文献
57.
Fábio Teixeira Kuhn Fabíola Trevizol Verônica Tironi Dias Raquel Cristine Silva Barcelos Camila Simonetti Pase Karine Roversi Caren Tatiane de David Antoniazzi Katiane Roversi Nardeli Boufleur Dalila Moter Benvegnú Tatiana Emanuelli Marilise Escobar Bürger 《Toxicology letters》2015
Chronic consumption of processed food causes structural changes in membrane phospholipids, affecting brain neurotransmission. Here we evaluated noxious influences of dietary fats over two generations of rats on amphetamine (AMPH)-conditioned place preference (CPP). Female rats received soybean oil (SO, rich in n-6 fatty acids (FA)), fish oil (FO, rich in n-3 FA) and hydrogenated vegetable fat (HVF, rich in trans fatty acids (TFA)) for two successive generations. Male pups from the 2nd generation were maintained on the same supplementation until 41 days of age, when they were conditioned with AMPH in CPP. While the FO group showed higher incorporation of n-3 polyunsaturated-FA (PUFA) in cortex/hippocampus, the HVF group showed TFA incorporation in these same brain areas. The SO and HVF groups showed AMPH-preference and anxiety-like symptoms during abstinence. Higher levels of protein carbonyl (PC) and lower levels of non-protein thiols (NPSH) were observed in cortex/hippocampus of the HVF group, indicating antioxidant defense system impairment. In contrast, the FO group showed no drug-preference and lower PC levels in cortex. Cortical PC was positively correlated with n-6/n-3 PUFA ratio, locomotion and anxiety-like behavior, and hippocampal PC was positively correlated with AMPH-preference, reinforcing connections between oxidative damage and AMPH-induced preference/abstinence behaviors. As brain incorporation of trans and n-6 PUFA modifies its physiological functions, it may facilitate drug addiction. 相似文献
58.
Embryonic tissues were obtained from normal (C) and thyroidectomized (T) rats between 9 and 21 days of pregnancy. We determined the number and weight, as well as the T4 and T3 contents (RIA), of 9- to 12-day-old embryotrophoblasts, of 13- to 21-day-old embryos and placentas, and of liver, lung, and brain from 20- and 21-day-old fetuses. T4 and T3 were found in all samples obtained from C dams, both before and after onset of fetal thyroid function. Despite low levels of both iodothyronines in fetal plasma near term, their concentrations in fetal brain and lung had reached half the maternal values. The T3/T4 ratio in fetal organs was the same, or higher, than in adult rats. Maternal thyroidectomy resulted in a marked decrease of the number and individual weights of viable conceptuses, throughout gestation. Fetal organ weights near term were also decreased, and changes were found in brain DNA and protein concentrations. T4 and T3 were undetectable in all embryotrophoblasts, embryos and placentas obtained from T dams before onset of fetal thyroid secretion. They were still markedly reduced in 21-day-old placentas. Total extrathyroidal contents of T3 and T4 in 20- and 21-day-old fetuses from T dams were also low as compared to those from normal mothers, but individual organs were not affected to the same degree. Thus concentrations were decreased in the carcass (whole embryo minus the trachea + thyroid + liver + lung + brain), but normal in the brain. These results show that maternal hypothyroidism is accompanied by thyroid hormone deficiency of the conceptus before the fetal thyroid functions. After this, alterations of T4 and T3 concentrations persist until term. Development is also delayed. Thus, adverse effects of maternal hypothyroidism may be due, at least in part, to the thyroid hormone deficiency of the embryonic tissues, and not only to the hypothyroid condition of the mother. 相似文献
59.
S Duran-Garcia J Gomez-Nieto M Fouchereau-Peron V F Padron M J Obregon G Morreale de Escobar F Escobar del Rey 《Clinical endocrinology》1979,11(3):275-290
Several weeks after thyroidectomy (T), female rats stopped growing, and their pituitary GH content had decreased to less than 2--3% of the values found for age-matched controls (C). The liver membranes of such animals were explored with human GH (hGH). It was found that in the severely hypothyroid T rat, the number, but not the affinity, of the lactogenic binding sites was markedly reduced. Treatment of these rats for 3 weeks with 1.75 micrograms or T4 or 0.5 micrograms T3/100 g body weight/day restored growth, increased pituitary GH content and restored the number of liver lactogenic binding sites were practically to normal. As regards the lactogenic binding sites, similar results were obtained when the severely hypothyroid rats were treated with a much lower T4 dose (0.2 microgram/100 g/day): this dose was clearly growth promoting, and restored to normal both the low circulating GH levels and the pituitary PRL content of the severely hypothyroid rat. The changes in plasma PRL were not clear. The lactogenic binding sites on liver membranes from rats which were both thyroidectomized and hypophysectomized were decreased in number. Treatment with 0.5 microgram T3/100 g/day for 30 days (but not for 12 days) resulted in an increase in the number of lactogenic binding sites, though it did not affect growth or the undetectable plasma GH levels. The effect on the lactogenic binding sites was less marked than in T rats with an intact pituitary. It would appear that minute amounts of thyroid hormones are needed for maintenance of liver lactogenic binding sites; it is possible that this not only occurs through mechanism(s) which involve the pituitary, but also through others which do not. The possible role of these receptors in growth processes is not yet clearly understood. 相似文献
60.
Thyroid destruction leading to endemic myxoedematous cretinism is highly prevalent in central Africa, where iodine (I) and selenium (SE) deficiencies as well as thiocyanate (SCN) overload are combined. All three factors have been studied experimentally in the etiology of the disease, but they have never been studied in combination. In a model using rats, we have previously shown that combining I and SE deficiencies increases the sensitivity of the thyroid to necrosis after iodide overload, an event unlikely to occur in the African situation. To develop a model that would more closely fit with the epidemiological findings, we have determined whether an SCN overload would also result in thyroid necrosis as does the I overload. The combination of the three factors increased by 3.5 times the amount of necrotic cells, from 5.5 +/- 0.3% in the I-SE+ thyroids to 18.9 +/- 1.6% in the I-SE-SCN-overloaded ones. Methimazole administration prevented the SCN-induced necrosis. SE- thyroids evolved to fibrosis, whereas SE+ thyroids did not. TGFbeta was prominent in macrophages present in SE- glands. Thyroid destruction in central Africa might therefore originate from the interaction of three factors: I and SE deficiencies by increasing H(2)O(2) accumulation, SE deficiency by decreasing cell defense and promoting fibrosis, and SCN overload by triggering follicular cell necrosis. 相似文献