全文获取类型
收费全文 | 2630篇 |
免费 | 196篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 58篇 |
妇产科学 | 80篇 |
基础医学 | 417篇 |
口腔科学 | 213篇 |
临床医学 | 219篇 |
内科学 | 622篇 |
皮肤病学 | 71篇 |
神经病学 | 263篇 |
特种医学 | 31篇 |
外科学 | 236篇 |
综合类 | 6篇 |
预防医学 | 213篇 |
眼科学 | 34篇 |
药学 | 205篇 |
中国医学 | 11篇 |
肿瘤学 | 128篇 |
出版年
2023年 | 39篇 |
2022年 | 63篇 |
2021年 | 155篇 |
2020年 | 77篇 |
2019年 | 128篇 |
2018年 | 143篇 |
2017年 | 89篇 |
2016年 | 97篇 |
2015年 | 123篇 |
2014年 | 132篇 |
2013年 | 156篇 |
2012年 | 266篇 |
2011年 | 253篇 |
2010年 | 123篇 |
2009年 | 116篇 |
2008年 | 161篇 |
2007年 | 140篇 |
2006年 | 144篇 |
2005年 | 104篇 |
2004年 | 96篇 |
2003年 | 51篇 |
2002年 | 50篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 12篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有2834条查询结果,搜索用时 31 毫秒
1.
Human papillomavirus genotype distribution in low-grade cervical lesions: comparison by geographic region and with cervical cancer. 总被引:13,自引:0,他引:13
Gary M Clifford Rashida K Rana Silvia Franceschi Jennifer S Smith Gerald Gough Jeanne M Pimenta 《Cancer epidemiology, biomarkers & prevention》2005,14(5):1157-1164
Low-grade squamous intraepithelial lesions (LSIL) associated with certain human papillomavirus (HPV) genotypes may preferentially progress to cervical cancer. HPV genotyping may thus have the potential to improve the effectiveness of screening programs and to reduce overtreatment. LSIL cases (n = 8,308) from 55 published studies were included in a meta-analysis. HPV genotype distribution was assessed by geographic region and in comparison with published data on cervical squamous cell carcinoma (SCC). HPV detection in LSIL was 80% in North America but less than 70% in other regions, most likely reflecting regional differences in LSIL diagnosis. Among 5,910 HPV-positive LSILs, HPV16 was the most common genotype (26.3%) followed by HPV31 (11.5%), HPV51 (10.6%), and HPV53 (10.2%). HPV-positive LSILs from Africa were 2-fold less likely to be infected with HPV16 than those in Europe, and HPV-positive LSILs from North America were more likely to be infected with HPV18 than those from Europe or South/Central America. Interpretation for rarer genotypes was hampered by variation in HPV testing methodology. SCC/LSIL prevalence ratios indicated that HPV16 was 2-fold and HPV18 was 1.5-fold more common in SCC than in HPV-positive LSIL, thus appearing more likely to progress than other high-risk genotypes (SCC/LSIL prevalence ratios between 0.05 and 0.85). HPV53 and HPV66 showed SCC/LSIL ratios of 0.02 and 0.01, respectively. HPV genotype distribution in LSIL differs from that in cervical cancer, highlighting the importance of HPV genotype in the risk of progression from LSIL to malignancy. Some regional differences in the relative importance of HPV genotypes in LSIL were noted. 相似文献
2.
3.
Tzu G Wu William A Rose Thomas B Albrecht Eugene P Knutson Rolf K?nig Joana R Perdig?o Alexandra P A Nguyen W Robert Fleischmann 《Journal of interferon & cytokine research》2007,27(1):13-22
Long-term treatment of mouse cancer cells with interferon-alpha (IFN-alpha) converts parental B16 melanoma cells to B16alpha vaccine cells. Inoculation of syngeneic mice with B16alpha vaccine cells triggers immunity to the parental B16 tumor that is mediated by host macrophages, T cells, and natural killer (NK) cells. Lymph node cells from mice inoculated with irradiated B16alpha vaccine cells, but not with irradiated parental cells, proliferate when cultured in vitro, suggesting long-term in vivo activation of lymphoid cells. Long-term IFN-alpha treatment of B16alpha vaccine cells induced both interleukin-15 (IL-15) mRNA and IL-15 protein. The bulk of the induced IL-15 remained cell associated, either cytoplasmic or associated with the cell membrane. Immunofluorescence microscopy studies showed that the cell-associated IL-15 was broadly distributed throughout the cytoplasm. These observations suggest that long-term IFN-alpha treatment may induce primarily the truncated isoform of IL-15. Vaccination with irradiated B16alpha vaccine cells may promote tumor immunity by releasing high levels of cell-associated IL-15 when spontaneously lysed or directly killed by innate immune cells. The release of accumulated cell-associated IL-15 may then trigger a host T cell response to tumor antigens and cause host development of immunity to the B16 tumor cells. 相似文献
4.
Mário Martins Oliveira Nogueira da Silva Ana Teresa Timóteo Joana Feliciano Lídia de Sousa Sofia Santos Fernando Marques Rui Ferreira 《Revista portuguesa de cardiologia》2007,26(7-8):691-702
Atrial electrical remodeling plays a part in recurrence of atrial fibrillation (AF). It has been related to an increase in heterogeneity of atrial refractoriness that facilitates the occurrence of multiple reentry wavelets and vulnerability to AF. AIM: To examine the relationship between dispersion of atrial refractoriness (Disp_A) and vulnerability to AF induction (A_Vuln) in patients with clinical paroxysmal AF (PAF). METHODS: Thirty-six patients (22 male; age 55+/-13 years) with > or =1 year of history of PAF (no underlying structural heart disease--n=20, systemic hypertension--n=14, mitral valve prolapse--n=1, surgically corrected pulmonary stenosis--n=1), underwent electrophysiological study (EPS) while off medication. The atrial effective refractory period (AERP) was assessed at five different sites--high (HRA) and low (LRA) lateral right atrium, high interatrial septum (IAS), proximal (pCS) and distal (dCS) coronary sinus--during a cycle length of 600 ms. AERP was taken as the longest S1-S2 interval that failed to initiate a propagation response. Disp_A was calculated as the difference between the longest and shortest AERP. A_Vuln was defined as the ability to induce AF with 1-2 extrastimuli or with incremental atrial pacing (600-300 ms) from the HRA or dCS. The EPS included analysis of focal electrical activity based on the presence of supraventricular ectopic beats (spontaneous or with provocative maneuvers). The patients were divided into group A--AF inducible (n=25) and group B--AF not inducible (n=11). Disp_A was analyzed to determine any association with A_Vuln. Disp_A and A_Vuln were also examined in those patients with documented repetitive focal activity. Logistic regression was used to determine any association of the following variables with A_Vuln: age, systemic hypertension, left ventricular hypertrophy, left atrial size, left ventricular function, duration of PAF, documented atrial flutter/tachycardia and Disp_A. RESULTS: There were no significant differences between the groups with regard to clinical characteristics and echocardiographic data. AF was inducible in 71% of the patients and noninducible in 29%. Group A had greater Disp_A compared to group B (105+/-78 ms vs. 49+/-20 ms; p=0.01). Disp_A was >40 ms in 50% of the patients without A_Vuln and in 91% of those with A_Vuln (p=0.05). Focal activity was demonstrated in 14 cases (39%), 57% of them with A_Vuln. Disp_A was 56+/-23 ms in this group and 92+/-78 ms in the others (p=0.07). Using logistic regression, the only predictor of A_Vuln was Disp_A (p=0.05). CONCLUSION: In patients with paroxysmal AF, Disp_A is a major determinant of A_Vuln. Nevertheless, the degree of nonuniformity of AERP appears to be less important as an electrophysiological substrate for AF due to focal activation. 相似文献
5.
Joana Correia Fátima Franco Silva Carla Roque Henrique Vieira Luís Augusto Providéncia 《Revista portuguesa de cardiologia》2007,26(4):335-343
BACKGROUND: High rates of morbidity and mortality are observed in patients with advanced heart failure (AHF). AHF is now considered the most costly syndrome in cardiology owing to the substantial economic burden associated with hospitalizations for acute decompensation. A management program that involves specialized follow-up by a multidisciplinary team has been suggested as a desirable strategy for improving outcomes for these patients. ObjectivE: To evaluate the impact of a specialized outpatient heart failure (HF) follow-up program for patients with AHF on frequency and duration of hospitalization for HF and functional status. METHODS: We retrospectively studied 167 consecutive patients with AHF who were referred to the outpatient HF follow-up program in our institution between January and November 2002, of whom 147 followed for > or =30 days were included in the analysis. In addition to demographic and baseline clinical characteristics, HF medication and NYHA functional class, the number and duration of hospitalizations for HF during the previous 12 months were recorded and compared at the time of referral and after a follow-up period of 6.5+/-3 months. RESULTS: Of the 147 patients analyzed (aged 60.8+/-13 years; 79% male; left ventricular ejection fraction 27+/-11%), 67% were in NYHA functional class III, 20% in class II and 13% in class IV at the time of referral. There was a significant improvement in functional class during the mean follow-up period: 55% of the patients were in class III, 37% in class II, 5% in class I and 3% in class IV (p<0.0001). The proportion of patients on beta-blockers or spironolactone increased from 33% and 51% at the time of referral to 69% and 71% respectively after referral (p<0.0001). In the 12 months before referral, 39% of the patients had been hospitalized for acute decompensation of HF (87 hospitalizations - mean 7.2/month) versus 13% of the patients during the mean follow-up period (25 hospitalizations - 3.8/month, p<0.0001). No significant differences were found in the proportion of patients on angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, digoxin or diuretics, or in the mean duration of hospitalization before and after referral. ConclusioN: The specialized follow-up of patients with AHF by a team with expertise in HF resulted in significant therapeutic optimization. Increased use of beta-blockers and spironolactone was associated with significant improvement in functional capacity and significant reduction in hospitalizations. 相似文献
6.
7.
Dina Ruano António Macedo Ana Dourado Maria Jo?o Soares José Valente Isabel Coelho Vítor Santos Maria Helena Azevedo Ann Goodman Mara Helena Hutz Clarissa Gama Maria Inês Lobato Paulo Belmonte-de-Abreu Joana Almeida Palha 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2004,(1):41-45
8.
de Andrade AL Pimenta FC Laval CA de Andrade JG Guerra ML Brandileone MC 《Journal of clinical microbiology》2004,42(5):2345-2346
We present a case of invasive pneumococcal infection in a healthy 10-month-old infant from whom Streptococcus pneumoniae serotype 23F was isolated from the blood and serotype 23B was isolated from the cerebrospinal fluid. Both serotypes were penicillin nonsusceptible. Pulsed-field gel electrophoresis analysis demonstrated that the two serotypes had distinct DNA patterns, indicating that infection did not occur as a result of capsular transformation but as a result of a mixed infection with two distinct pneumococcal serotypes. 相似文献
9.
Genetic relationship between Streptococcus pneumoniae isolates from nasopharyngeal and cerebrospinal fluid of two infants with Pneumococcal Meningitis
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
de Andrade AL Pimenta FC Brandileone MC Laval CA Guerra ML de Andrade JG Di Fabio JL 《Journal of clinical microbiology》2003,41(8):3970-3972
The molecular epidemiology of Streptococcus pneumoniae isolates from carriage and cerebrospinal fluid (CSF) concurrently recovered from the same individual has not yet been reported. By using pulsed-field gel electrophoresis, we demonstrated the genetic linkage among strains from CSF and nasopharynges of two children with pneumococcal meningitis. 相似文献
10.
Paredes J Milanezi F Viegas L Amendoeira I Schmitt F 《Virchows Archiv : an international journal of pathology》2002,440(1):16-21
Cadherins are calcium-dependent cell-cell adhesion glycoproteins, separated into several subclasses with distinct adhesive specificities and tissue distribution, which play an important role in many cellular events. We analyse the expression of E-, N- and P-cadherin in a series of ductal carcinoma in situ (DCIS) of the breast, since this disease represents a heterogeneous group, with different risks of progression to invasive breast carcinoma. We also studied the correlation between cadherin expression and DCIS classification systems, namely the Van Nuys and the Holland et al. classification, this latter based on cytonuclear differentiation and cell polarity. Our results showed that, regardless the classification applied, P-cadherin expression is strongly associated with high histological grade of DCIS (P=0.0047) and lack of estrogen receptors (P=0.0008). The use of Holland et al. classification showed a significant correlation between P-cadherin expression and decreased cell polarity (P=0.01). In conclusion, P-cadherin expression seems to be more relevant in DCIS pathogenesis than the altered expression of any other cadherin, including the decrease of E-cadherin expression. 相似文献