全文获取类型
收费全文 | 7187篇 |
免费 | 429篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 34篇 |
儿科学 | 318篇 |
妇产科学 | 162篇 |
基础医学 | 741篇 |
口腔科学 | 423篇 |
临床医学 | 702篇 |
内科学 | 1768篇 |
皮肤病学 | 100篇 |
神经病学 | 697篇 |
特种医学 | 299篇 |
外科学 | 828篇 |
综合类 | 44篇 |
一般理论 | 2篇 |
预防医学 | 299篇 |
眼科学 | 81篇 |
药学 | 523篇 |
中国医学 | 4篇 |
肿瘤学 | 620篇 |
出版年
2023年 | 47篇 |
2022年 | 71篇 |
2021年 | 140篇 |
2020年 | 81篇 |
2019年 | 120篇 |
2018年 | 161篇 |
2017年 | 134篇 |
2016年 | 127篇 |
2015年 | 155篇 |
2014年 | 217篇 |
2013年 | 258篇 |
2012年 | 353篇 |
2011年 | 384篇 |
2010年 | 253篇 |
2009年 | 206篇 |
2008年 | 380篇 |
2007年 | 413篇 |
2006年 | 369篇 |
2005年 | 358篇 |
2004年 | 299篇 |
2003年 | 285篇 |
2002年 | 268篇 |
2001年 | 222篇 |
2000年 | 231篇 |
1999年 | 252篇 |
1998年 | 100篇 |
1997年 | 95篇 |
1996年 | 84篇 |
1995年 | 81篇 |
1994年 | 49篇 |
1993年 | 53篇 |
1992年 | 140篇 |
1991年 | 138篇 |
1990年 | 122篇 |
1989年 | 121篇 |
1988年 | 105篇 |
1987年 | 103篇 |
1986年 | 91篇 |
1985年 | 69篇 |
1984年 | 61篇 |
1983年 | 46篇 |
1982年 | 27篇 |
1981年 | 39篇 |
1980年 | 27篇 |
1979年 | 52篇 |
1978年 | 24篇 |
1977年 | 24篇 |
1976年 | 30篇 |
1969年 | 25篇 |
1966年 | 19篇 |
排序方式: 共有7645条查询结果,搜索用时 31 毫秒
71.
The search for further variation at the APOE gene in a sample of patients with sporadic late-onset Alzheimer's disease (AD) and related controls revealed two different mutations in the exon 3 of the gene. One, the Leu28-->Pro, always found on an APOE e(*)4 allele, was present in five of the 94 patients and in 1 of the 157 controls. The other, Thr42-->Ala, found on an e(*)3 allele, was observed in only one AD patient, who also carried the Leu28-->Pro, but in none of the controls.In the AD patient group the allele e(*)4(-), corresponding to Leu28-->Pro, showed a frequency of 0.027, compared with only 0.003 in the controls. Compared to E3/3 and E3/2 genotypes, the risk of developing AD associated with the genotypes carrying the e(*)4 allele, the well-established risk allele for AD onset, was observed to be high (OR=3.16; 95% CI=1.62-6.20; P=0.0009), but the risk associated with genotypes carrying the Leu28-->Pro mutation was higher still (OR=10.95; 95% CI=1.25-95.75; P=0.015). The higher risk associated with this mutation was assessed by meta-analysis carried out using the data of three patient groups from a previously published study Kamboh et al. and from our study. The results indicated that, compared with all the other APOE genotypes, those carrying the Leu28-->Pro mutation were at a substantially higher risk of developing AD (OR=4.25; 95% CI=1.21-14.97). 相似文献
72.
Peruhype-Magalhães V Martins-Filho OA Prata A Silva Lde A Rabello A Teixeira-Carvalho A Figueiredo RM Guimarães-Carvalho SF Ferrari TC Correa-Oliveira R 《Scandinavian journal of immunology》2005,62(5):487-495
We investigated the cytokine profile of cells of the innate immune response and its association with active (ACT), asymptomatic (AS) and cured (CUR) human visceral leishmaniasis (VL), as well as noninfected (NI) subjects. The frequency of cytokine-producing cells was determined after short-term in vitro incubation of whole peripheral blood samples with soluble Leishmania antigen (SLA). Our data demonstrated a predominant type 2 cytokine profile in NI and ACT. In NI, we observed an increase of IL-4+ neutrophils, IL-10+ eosinophils besides a decrease of tumour necrosis factor (TNF)-alpha+ eosinophils/monocytes. Yet in ACT, we observed an increase of IL-4+ neutrophils and natural killer (NK) cells and IL-10+ monocytes, a reduced frequency of IL-12+ and IFN-gamma+ eosinophils and lower levels of TNF-alpha+ and IL-12+ monocytes. AS presented a mixed profile, characterized by an increase of IFN-gamma+ neutrophils/eosinophils and NK cells, of IL-12+ eosinophils/monocytes, as well as increase of IL-4+ neutrophils and NK cells and IL-10+ eosinophils/monocytes. In contrast, CUR was characterized by a type 1 response with an increase of IFN-gamma+ neutrophils/eosinophils and NK cells, associated with an increase in IL-12+ monocytes. In conclusion, we show a correlation between innate immune cytokine patterns and clinical status of VL, suggesting that these cells, in addition to other factors, may contribute to the cytokine microenvironment in which Leishmania-specific T cells are primed and to disease outcome. 相似文献
73.
Abnormal skeletal and cardiac muscle mitochondria induced by zidovudine (AZT) in human muscle in vitro and in an animal model. 总被引:1,自引:0,他引:1
L Lamperth M C Dalakas F Dagani J Anderson R Ferrari 《Laboratory investigation; a journal of technical methods and pathology》1991,65(6):742-751
To examine the mechanism of mitochondrial myocytotoxicity caused by long-term administration of zidovudine (AZT) in human immunodeficiency virus-positive patients, we examined the effect of AZT in vitro on human muscle in tissue culture and in vivo in rats treated with daily intraperitoneal injections of AZT at doses equivalent to the total daily dose used in acquired immunodeficiency syndrome patients. After 19 days, the AZT-treated myotubes in tissue culture exhibited abnormal mitochondria characterized by proliferation (mean +/- SD, 27.5 +/- 8 mitochondria/16 microns2 surface area, compared with 12.8 +/- 4 in the control cultures (p less than 0.001], enlarged size, abnormal cristae and electron-dense deposits in their matrix. The changes were partially reversible after AZT withdrawal. Rats treated with AZT developed weight loss, 100-fold elevation of creatine kinase, and increased serum lactate and glucose. In tissues, AZT had its highest concentration in the skeletal muscle and the heart. Skeletal and heart muscles from the treated animals, but not the controls, showed enlarged mitochondria with disorganized or absent cristae and electron-dense deposits in their matrix. Study of the mitochondrial functions assessed by evaluating stimulated oxygen consumption rate, enzymatic activities of electron transport chain and coupling state of oxidative phosphorylation (respiratory control ratio) revealed a decrease in rotenone-sensitive NADH cytochrome C reductase (complex I + III) and an uncoupling effect demonstrated by decreased respiratory control ratio. We conclude that AZT, a DNA chain terminator, is a muscle mitochondrial toxin that affects the oxidation-phosphorylation coupling and the activity of complex I and III of the mitochondrial respiratory chain. 相似文献
74.
Ferrari G Neal W Jones A Olender N Ottinger J Ha R McElrath MJ Goepfert P Weinhold KJ 《Immunology letters》2001,79(1-2):37-45
We evaluated MHC-class I-restricted CTL responses induced by HIV-1 clade B-based vaccines in nine HIV-1 seronegative vaccine recipients with regard to their patterns of HLA restriction and epitope recognition. We found that seven of nine volunteers developed detectable CTL reactivities against novel epitopes within the HIV-1 Env and Gag proteins. Although four of nine subjects were HLA-A*0201, none of the cellular responses was restricted in the context of this allele. The type of responses observed in this sampling of vaccines appeared similar to those reported during primary infection and among long term non-progressors, with three out of nine subjects recognizing HLA-B27 or HLA-B17(57)-restricted epitopes. Although the majority of CTL responses were directed against novel epitopes, these effectors were still able to mediate cross-clade reactivities. 相似文献
75.
The deltaccr5 mutation conferring protection against HIV-1 in Caucasian populations has a single and recent origin in Northeastern Europe 总被引:6,自引:0,他引:6
Libert F; Cochaux P; Beckman G; Samson M; Aksenova M; Cao A; Czeizel A; Claustres M; de la Rua C; Ferrari M; Ferrec C; Glover G; Grinde B; Guran S; Kucinskas V; Lavinha J; Mercier B; Ogur G; Peltonen L; Rosatelli C; Schwartz M; Spitsyn V; Timar L; Beckman L; Vassart G 《Human molecular genetics》1998,7(3):399-406
The chemokine receptor CCR5 is encoded by the CMKBR5 gene located on the
p21.3 region of human chromosome 3, and constitutes the major co- receptor
for the macrophage-tropic strains of HIV-1. A mutant allele of the CCR5
gene, Delta ccr5 , was shown to provide to homozygotes with a strong
resistance against infection by HIV. The frequency of the Delta ccr5 allele
was investigated in 18 European populations. A North to South gradient was
found, with the highest allele frequencies in Finnish and Mordvinian
populations (16%), and the lowest in Sardinia (4%). Highly polymorphic
microsatellites (IRI3.1, D3S4579 and IRI3.2, D3S4580 ) located respectively
11 kb upstream and 68 kb downstream of the CCR5 gene deletion were used to
determine the haplotype of the chromosomes carrying the Delta ccr5 variant.
A strong linkage disequilibrium was found between Delta ccr5 and specific
alleles of the IRI3.1 and IRI3.2 microsatellites: >95% of the Delta ccr5
chromosomes carried the IRI3.1-0 allele, while 88% carried the IRI3.2-0
allele. These alleles were found respectively in only 2 or 1.5% of the
chromosomes carrying a wild-type CCR5 gene. From these data, it was
inferred that most, if not all Delta ccr5 alleles originate from a single
mutation event, and that this mutation event probably took place a few
thousand years ago in Northeastern Europe. The high frequency of the Delta
ccr5 allele in Caucasian populations cannot be explained easily by random
genetic drift, suggesting that a selection advantage is or has been
associated with homo- or heterozygous carriers of the Delta ccr5 allele.
相似文献
76.
Alessandro Assandri Antonio Perazzi Pietro Ferrari Edoardo Martinelli Ambrogio Ripamonti Giorgio Tarzia Giorgio Tuan 《Naunyn-Schmiedeberg's archives of pharmacology》1985,328(3):341-347
Summary Healthy volunteers administered orally a single dose (20 mg) of [2-14C]zetidoline, a new dopamine antagonist, exhibited rapid absorption of radioactivity with peak plasma levels of 250–300 ng/ml achieved in 1 h. The compound underwent intensive metabolic first-pass so that plasma radioactivity was represented mostly by two products, metabolite B endowed with neuroleptic activity, and metabolite D inactive, while unchanged zetidoline was not detected. Disappearance of radioactivity from plasma was rapid with a half-life of 1.78±0.20 h.The simultaneous assay of plasma prolactin showed increased levels of the hormone (+464% at the peak time) up to the 6th h after dosing, with plasma concentration profile which mimic those of metabolite B.The radioactive test-dose was eliminated mainly via the kidneys with an average urinary recovery of 84.7±1.7% in 4 days (73.4±1.1% within 8 h). The main urinary metabolite (metabolite G) and two minor ones (metabolites B and D) were purified and their structures assigned by IR, MS and NMR spectroscopy, they are: 1-(3-chloro-4-hydroxyphenyl)-3[2-(3,3-dimethyl-1-azetidinyl)ethyl]imidazolidin-2-one, metabolite B; 1-[2-(3,3-dimethyl-1-azetidinyl)ethyl]imidazolidin-2-one, metabolite D and the 4-O-sulphate ester of metabolite B, metabolite G.The metabolic fate of zetidoline in man follows the same phase I reactions demonstrated in rats and dogs, while the phase II reaction is sulphoconjugation instead of the glucuronidation observed in animals. 相似文献
77.
Braga M Baccari P Cristallo M Staudacher C Ferrari G Scaccabarozzi S DiPalo S DiCarlo V 《Clinical nutrition (Edinburgh, Scotland)》1984,3(4):231-235
Between June 1981 and June 1983 the delayed hypersensitivity response (DHR) was studied in 401 patients considered for major surgical procedure: 320 of these patients underwent surgery. The incidence of sepsis and postoperative mortality was higher in anergic and relative anergic patients than in normal responders (p<0.001). To evaluate whether DHR depression in cancer patients was due to the direct effect of cancer or to tumour-linked malnutrition, the 401 patients were divided into 4 groups: 1) 140 malnourished cancer patients, 2) 51 malnourished non-cancer patients, 3) 120 well-nourished cancer patients and 4) 90 well-nourished non-cancer patients. The mean age was not significantly different for the 4 groups. The results showed a relationship between DHR and nutritional status (p<0.001). The tumour-related DHR impairment disappeared when the cancer and non-cancer patient groups were homogeneous with regard to their nutritional status. Therefore, the tumour was able to determine the DHR depression because of the cancer-linked malnutrition. We did not observe any relationship between local extension of the tumour and lymph node involvement and DHR depression. In 90 well-nourished non-cancer patients the relation between DHR and age was investigated. The incidence of anergy and relative anergy was higher in patients over 59 years than in patients under 60 years (p<0.001). 相似文献
78.
Humberto Pea-Jorquera Valentina Campos-Núez Kabir P. Sadarangani Gerson Ferrari Carlos Jorquera-Aguilera Carlos Cristi-Montero 《Nutrients》2021,13(4)
This study aimed to determine whether pupils who have breakfast just before a cognitive demand, do not regularly skip breakfast, and consume a high-quality breakfast present higher cognitive performance than those who do not; furthermore, to establish differences according to their nutritional status. In this study, 1181 Chilean adolescents aged 10–14 years participated. A global cognitive score was computed through eight tasks, and the body mass index z-score (BMIz) was calculated using a growth reference for school-aged adolescents. The characteristics of breakfast were self-reported. Analyses of covariance were performed to determine differences in cognitive performance according to BMIz groups adjusted to sex, peak height velocity, physical fitness global score, and their schools. A positive association was found in adolescents’ cognitive performance when they had breakfast just before cognitive tasks, did not regularly skip breakfast, presented at least two breakfast quality components, and included dairy products. No significant differences were found between breakfast components, including cereal/bread and fruits/fruit juice. Finally, pupils who were overweight/obese who declared that they skipped breakfast regularly presented a lower cognitive performance than their normal-BMIz peers. These findings suggest that adolescents who have breakfast just prior to a cognitive demand and regularly have a high quality breakfast have better cognitive performance than those who do not. Educative nutritional strategies should be prioritized, especially in “breakfast skippers” adolescents living with overweight/obesity. 相似文献
79.
Amadio Eliane Martins Marcos Rodrigo Labat Serra Andrey Jorge dos Santos Solange Almeida Caires Jheniphe Rocha Fernandes Guilherme Henrique Cardosos Leal-Junior Ernesto Cesar Ferrari João Carlos Correa de Tarso Camillo de Carvalho Paulo 《Lasers in medical science》2021,36(7):1427-1435
Lasers in Medical Science - Photobiomodulation therapy (PBMT) has been indicated for enforcement on healing skin wounds. This study evaluated the effects of PBMT on the healing of skin wounds... 相似文献
80.
Belotti Francesco Tengattini Francesco Mattavelli Davide Ferrari Marco Fiorentino Antonio Agnelli Silvia Schreiber Alberto Nicolai Piero Fontanella Marco Maria Doglietto Francesco 《Neurosurgical review》2021,44(1):279-287
Neurosurgical Review - Recently, endoscopic transsphenoidal transclival approaches have been developed and their role is widely accepted for extradural pathologies. Their application to intradural... 相似文献