全文获取类型
收费全文 | 1006篇 |
免费 | 36篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 18篇 |
儿科学 | 9篇 |
妇产科学 | 54篇 |
基础医学 | 157篇 |
口腔科学 | 56篇 |
临床医学 | 70篇 |
内科学 | 257篇 |
皮肤病学 | 11篇 |
神经病学 | 83篇 |
特种医学 | 22篇 |
外科学 | 117篇 |
综合类 | 4篇 |
预防医学 | 68篇 |
眼科学 | 12篇 |
药学 | 75篇 |
中国医学 | 18篇 |
肿瘤学 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 16篇 |
2021年 | 23篇 |
2020年 | 18篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 23篇 |
2016年 | 23篇 |
2015年 | 31篇 |
2014年 | 33篇 |
2013年 | 51篇 |
2012年 | 79篇 |
2011年 | 103篇 |
2010年 | 53篇 |
2009年 | 54篇 |
2008年 | 82篇 |
2007年 | 100篇 |
2006年 | 68篇 |
2005年 | 62篇 |
2004年 | 50篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有1044条查询结果,搜索用时 0 毫秒
1.
Geraldo F. Busatto Lyn S. Pilowsky Durval C. Costa John Mertehs Dirk Terriere Peter J. Ell Rachel Mulligan Michael J. Travis Josée E. Leysen Dominic Lui Sveto Gacinovic Wendy Waddington Anne Lingford-Hughes Robert W. Kerwin 《European journal of nuclear medicine and molecular imaging》1997,24(2):119-124
The mapping of 5-HT2 receptors in the brain using functional imaging techniques has been limited by a relative lack of selective radioligands.
Iodine-123 labelled 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide (123I-5-I-R91150 or123I-R93274) is a new ligand for single-photon emission tomography (SPET), with high affinity and selectivity for 5-HT2A receptors. This study reports on preliminary123I-5-I-R91150 SPET, wholebody and blood distribution findings in five healthy human volunteers. Maximal brain uptake was approximately
2% of total body counts at 180 min post injection (p.i.). Dynamic SPET sequences were acquired with the brain-dedicated, single-slice
multi-detector system SEM-810 over 200 min p.i. Early peak uptake (at 5 min p.i.) was seen in the cerebellum, a region free
from 5HT2A receptors. In contrast, radioligand binding in the frontal cortex increased steadily over time, up to a peak at approximately
100–120 min p.i. Frontal cortex-cerebellum activity ratios reached values of 1.4, and remained stable from approximately 100
min p.i. onwards. Multi-slice SPET sequences showed a pattern of regional variation of binding compatible with the autoradiographic
data on the distribution of 5-HT2A receptors in (cerebral cortex>striatum>cerebellum). These findings suggest that123I-5-I-R91150 may be used for the imaging of 5-HT2A receptors in the living human brain with SPET. 相似文献
2.
N K Nakagawa F Donato-Júnior C S Kondo M King J O C Auler-Júnior P H N Saldiva G Lorenzi-Filho 《The European respiratory journal》2004,24(5):805-810
Furosemide is a potent diuretic that affects water transfer across the respiratory epithelium, which is closely related to the transepithelial potential difference (PD). Water is a critical factor that determines mucus transport; an important lung defence mechanism that removes particles and microorganisms from the respiratory system. The aim of the present study was to investigate the acute effects of furosemide and hypovolaemia on tracheal PD and mucus properties. A total of 36 male mixed-breed dogs were submitted to anaesthesia, mechanical ventilation and haemodynamic monitoring. They were randomly assigned to three groups consisting of: a control group, a furosemide (40 mg i.v.) + hypovolaemia group, and a furosemide (40 mg i.v.) + volume replacement group. Tracheal PD and mucus samples were collected at time 0, 1 and 2 h after intervention. Mucus properties were analysed by means of a magnetic microrheometer and in vitro mucociliary transportability on the frog palate. Compared to controls, furosemide decreased PD to intermediate values, and only significantly when associated with hypovolaemia (-13+/-5 and -8+/-2 mV, time 0 and 2 h, respectively). In addition to the direct effect of furosemide, these results indicate that hypovolaemia also affects ion transport in the tracheal membrane. Furosemide and hypovolemia have no acute effects on respiratory mucus properties. 相似文献
3.
Albertini-Yagi CS Oliveira RC Vieira JE Negri EM de Oliveira LR Saldiva PH Lorenzi-Filho G 《Respiratory physiology & neurobiology》2005,145(1):101-110
The study objectives were to compare in vitro transportability and physical properties of respiratory mucus, obtained invasively by direct collection (DC) right after endotracheal intubation and non-invasively by sputum induction with 3% hypertonic saline solution inhalation (SI) 24 h before the anesthesia. Twenty-two patients with no pulmonary disease scheduled for elective abdominal surgical procedures were studied. The parameters analyzed and the main results are as follows. (1) Transportability by cilia (MCT), SI was higher than DC (0.94+/-0.25 and 0.62+/-0.25; P<0.001). There was a significant correlation between the two methods and DC could be estimated by: DC=0.21+(0.44 SI) (r=0.44; P<0.001). (2) Transportability by cough (CC), SI was higher than DC (68.23+/-32.1 and 33.58+/-19.04 mm; P=0.002). (3) Contact angle (CA), SI was lower than DC (10+/-3 degrees and 22+/-14 degrees ; P=0.025). (4) Rheological properties (no significant difference obtained between SI and DC). These results indicated that SI changes mucus physical properties and transportability in non-expectorators. 相似文献
4.
Presence of the cfxA gene in Bacteroides distasonis 总被引:1,自引:0,他引:1
Avelar KE Otsuki K Vicente AC Vieira JM de Paula GR Domingues RM Ferreira MC 《Research in microbiology》2003,154(5):369-374
In this study we investigated the presence of the cfxA gene (encoding a class A beta-lactamase) in 73 strains of the Bacteroides fragilis group belonging to the species B. distasonis (34), B. vulgatus (14), B. thetaiotaomicron (8), B. merdae (6), B. caccae (9) and B. ovatus (2) isolated from human intestinal microflora of healthy children and adults. Employing specific primers to the cfxA gene, a 312-bp amplified fragment was obtained in 2 strains of B. vulgatus and 9 strains, the majority from children, of B. distasonis. The expression of this enzyme was analysed by determining the MICs to cefoxitin and cefotaxime and values varied from 2 to >256 microg/ml of both cefoxitin and cefotaxime. Sequence analysis of the amplicons corresponding to the cfxA gene from B. distasonis and B. vulgatus revealed identical sequences between these isolates and high similarity with other beta-lactamase genes of anaerobes such as cfxA of B. vulgatus (99%) and cfxA2 of Prevotella intermedia (99%), both sequences of which deposited in Genbank under accession numbers U38243 and AF118110, respectively. However, a fragment obtained from a B. distasonis strain (EC17-4) showed a unique RFLP profile and 87% nucleotide similarity with cfxA and cfxA2 genes. These results seem to suggest a dissemination of these resistance determinants among Bacteroides species. 相似文献
5.
Mello MA Mascarenhas RE Ferraro GA Harn D Galvão-Castro M Bou-Habib DC 《Medical microbiology and immunology》2005,194(1-2):61-65
Patients infected with HIV-1 develop a potent humoral immune response against the virus, but HIV-1 primary isolates are remarkably resistant to neutralizing antibodies. Considering that the envelope glycoprotein of HIV-1 (gp120/41) is heavily glycosylated, we investigated whether anti-carbohydrate antibodies could inhibit HIV-1 infection in vitro. We studied the neutralizing activity of three monoclonal antibodies (mAbs) raised to carbohydrates of Schistosoma mansoni, against seven primary isolates of HIV-1. Assays were performed infecting peripheral blood mononuclear cells from normal donors with viral isolates previously treated with mAbs. Viral strains used were tropic for the coreceptors CCR5, CXCR4, and dual-tropic ones. We found that the anti-glycan mAbs vigorously inhibited HIV-1 infection, regardless of the preferential coreceptor usage of the isolate, in a dose-response manner. Importantly, five isolates were resistant to neutralization by two HIV-1 antibody-positive human sera endowed with potent anti-HIV-1 inhibitory activity. Our findings suggest that carbohydrates of the HIV-1 viral envelope may be a target of an effective humoral immune response elicited by vaccination.The first two authors contributed equally to this work 相似文献
6.
Elisabeth Meloni Vieira Alcyone Artioli Machado Geraldo Duarte Regina Helena Brito de Souza Antonio Luis Rodrigues Junior 《Pan American journal of public health》2004,15(6):373-379
OBJECTIVES: To study HIV-positive women and women at risk of becoming infected with HIV who attended HIV prevention education group sessions at a university hospital in Brazil and to compare the use of the female condom and the male condom by these two groups of women. METHODS: The study subjects were 165 women participating in HIV prevention education group sessions at the Medical School Hospital of Ribeir?o Preto of the University of S?o Paulo, in the city of Ribeir?o Preto, S?o Paulo, Brazil. Women could be enrolled in the study from August 2000 to June 2001, and the follow-up observation time period was from August 2000 to July 2001. Male condoms and female condoms were freely distributed to all the participants at the end of each educational session and also at the end of each follow-up visit that the participants made. Each woman took part in an initial interview and was asked to return monthly. At each follow-up visit an additional short interview was carried out in order to investigate use of the male condom and of the female condom. Variables that were examined for the study included age, education, ethnic group, marital or relationship status, number of children, the women's use of male condoms and female condoms, commercial sex (whether the women had ever had sex in exchange for money, gifts, or favors), and previous knowledge of the female condom. RESULTS: The 165 women studied fell into the following three categories: 132 of them (80.0%) were HIV-positive, 26 of them (15.8%) had a sexually transmitted disease (STD) other than HIV and did not have an HIV-positive partner, and 7 of them (4.2%) had an HIV-positive partner but did not have HIV or any other STD. The women ranged in age from 15 to 64 years, with a mean of 30.3 years. Of the women in the study, 69.7% of them were married or were cohabitating, and 90.9% of them had a sexual partner. Just over two-thirds of the women had seven years of formal schooling or less. Out of 163 women, a total of 31 of them (19.0%) had never used the male condom with a partner, and 49 of the 163 (30.1%) had not used a male condom at the time of the last sexual intercourse. Out of the 165 women, 74 of them (44.8%) returned for at least one follow-up visit. Of these 74 women, 58 of them (78.3%) reported using the female condom between the initial interview and the first follow-up visit. The majority of the 74 women who returned for a visit liked using the female condom, and the women reported that their partners also generally accepted the female condom. In comparison to women at risk of HIV, HIV-positive women were more likely to have used the male condom with a partner before the initial interview. Women who continued returning over a longer follow-up period were more likely to have used the female condom at the time of the last sexual intercourse. No association was found between female condom use at the time of last sexual intercourse and the woman's HIV infection status. CONCLUSIONS: In comparison to the women at risk of HIV, the HIV-positive women in our study were more likely to use male condoms with their partners, to return for follow-up visits, and to have a longer follow-up period. The acceptance of the female condom among the HIV-positive women in this study, as reported at their first follow-up visit, appears to be similar to the acceptance of the female condom among women in general in Brazil. 相似文献
7.
Martinho O Gonçalves A Moreira MA Ribeiro LF Queiroz GS Schmitt FC Reis RM Longatto-Filho A 《Gynecologic oncology》2008,111(2):350-355
ObjectivesUterine adenosquamous carcinoma (ASC) is an uncommon, yet, one of the most aggressive cervical cancer subtype. The successful treatment of some tumors, such as gastrointestinal stromal tumors (GISTs), by anti-KIT inhibitors fosters the study of this receptor tyrosine kinase in other malignancies. In the present study, we intended to molecularly characterize KIT in ASC.MethodsIn a series of 30 cases, we studied KIT (CD117), KIT phosphorylated / activated form, as well as KIT ligand, stem cell factor (SCF), by immunohistochemistry. We further screened for KIT hotspot mutations (exon 9, 11, 13 and 17) by PCR-SSCP and for KIT gene amplification by Quantitative real-time PCR in CD117 positive cases.ResultsWe observed CD117 expression in ~ 13% of cases, with ~ 7% co-expressing SCF, which resulted in KIT phosphorylation/activation. No KIT activating mutations or gene amplification were found, despite the presence of 4q aneuploidy in one case.ConclusionsThis is the first study assessing KIT activation and molecular alterations in a large series of rare ASC. Our findings showed the absence of KIT molecular alterations and suggested the presence of KIT activation in a small proportion of cases through KIT/SCF co-expression. 相似文献
8.
Noguti AS Jarmy-Di Bella ZI de Oliveira E Castro RA Lima GR Baracat EC Sartori MG Girão MJ 《European journal of obstetrics, gynecology, and reproductive biology》2008,141(2):183-185
Objective
We aimed to study the cross-sectional area of levator ani muscle and the doppler velocimetric parameters of vessels its in premenopausal and postmenopausal women.Study design
Sixty-four patients, divided into 3 groups, were assessed: group I (20 women—average age 28 years) premenopausal and nulliparous (control); group II (24 women—average age 38 years, vaginal delivery 1–4) premenopausal with vaginal deliveries; group III (20 women—average age 55 years, parity 0–4) postmenopausal without hormonal therapy. Doppler velocimetry of levator ani muscle vessels through resistance and pulsatility indices was used and the means of the groups compared by adjusting the weighed variance model with multiple comparisons, according to Tukey's method. Similarly, we measured the cross-sectional area of the muscle using ultrasonography.Results
There was a significant increase in resistance and pulsatility indices in postmenopausal patients as compared to the other two groups. We also observed a significant decrease in the cross-sectional area of the muscle of postmenopausal patients when compared to those in premenopausal.Conclusion
The obtained results allow us to conclude that levator ani muscle vascularization significantly decreases after menopause (age and/or hipoestrogenism) and that it can be assumed that vaginal delivery does not promote long-term alterations in levator ani muscle vascularization. We also observed a significant decrease in the cross-sectional area of the muscle in postmenopausal women when compared to those in premenopausal. 相似文献9.
10.
Lymphatic vessel density and epithelial D2-40 immunoreactivity in pre-invasive and invasive lesions of the uterine cervix 总被引:3,自引:0,他引:3
Longatto-Filho A Pinheiro C Pereira SM Etlinger D Moreira MA Jubé LF Queiroz GS Baltazar F Schmitt FC 《Gynecologic oncology》2007,107(1):45-51
OBJECTIVE: We sought to determine the significance of lymphatic vessel density (LVD) in pre-malignant lesions and carcinomas of the uterine cervix and to evaluate the prognostic value of lymphatic invasion and D2-40 positivity in tumor cells in the three histological types of invasive lesions. The correlation of LVD, lymphatic invasion and D2-40 positivity in tumor cells with EGFR and COX-2 expressions was also evaluated. METHODS: We studied 50 cervicitis, 50 low-grade squamous intraepithelial lesions (LSIL) (CIN1), 51 high-grade squamous intraepithelial lesions (HSIL) (CIN2/CIN3), 49 invasive squamous cells carcinomas (SCC), 43 adenocarcinomas (AC) and 30 adenosquamous cells carcinomas (ASC). The immunoreaction assay was performed using the monoclonal antibody D2-40. RESULTS: Significant differences in LVD were found among all categories of pre-invasive and invasive lesions (p=0.001 and p<0.001, respectively). LVD in invasive lesions was significantly greater than in pre-invasive lesions (p<0.001) and no significant association was found between LVD in invasive lesions and both lymph node invasion and/or metastasis. D2-40 positivity in tumor cells was associated with a better prognosis in ASC cases. EGFR and COX-2 expressions in invasive lesions were not associated with LVD; however, they correlated with both lymphatic invasion and D2-40 positivity in tumor cells. CONCLUSIONS: Lymphatic neovascularization begins early in intraepithelial lesions and continues to increase towards malignancy. Both lymphatic invasion and decrease in D2-40 expression in tumor cells appear to have a prognostic value. 相似文献