全文获取类型
收费全文 | 948篇 |
免费 | 74篇 |
国内免费 | 63篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 47篇 |
妇产科学 | 4篇 |
基础医学 | 89篇 |
口腔科学 | 24篇 |
临床医学 | 81篇 |
内科学 | 190篇 |
皮肤病学 | 24篇 |
神经病学 | 17篇 |
特种医学 | 258篇 |
外科学 | 40篇 |
综合类 | 62篇 |
预防医学 | 60篇 |
眼科学 | 5篇 |
药学 | 96篇 |
肿瘤学 | 86篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 13篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 19篇 |
2013年 | 23篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 19篇 |
2009年 | 29篇 |
2008年 | 16篇 |
2007年 | 38篇 |
2006年 | 21篇 |
2005年 | 35篇 |
2004年 | 17篇 |
2003年 | 21篇 |
2002年 | 20篇 |
2001年 | 30篇 |
2000年 | 16篇 |
1999年 | 29篇 |
1998年 | 56篇 |
1997年 | 66篇 |
1996年 | 60篇 |
1995年 | 57篇 |
1994年 | 35篇 |
1993年 | 43篇 |
1992年 | 20篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 48篇 |
1988年 | 37篇 |
1987年 | 34篇 |
1986年 | 18篇 |
1985年 | 21篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 14篇 |
1976年 | 10篇 |
1975年 | 7篇 |
排序方式: 共有1085条查询结果,搜索用时 17 毫秒
101.
102.
OBJECTIVE: Both AIDS and cervical neoplasia (CN) can result from sexual transmission of HIV infection and may affect similar groups of women. Available data on the association between AIDS and CN have practical implications for gynecological care. We review these data to provide an estimate of the magnitude of the association between CN and HIV infection. DESIGN: Twenty-one studies were reviewed, including reports and abstracts published from January 1986 to July 1990. Of these, five included a comparison group and had sufficient data for inclusion in the analysis. RESULTS: All five controlled studies reported a significant association between HIV infection and CN. One included women with both intraepithelial and invasive lesions; the other four considered women with intraepithelial lesions only. The summary odds ratio indicated that the odds of HIV-infected women having CN are 4.9 (95% confidence interval, 3.0-8.2) times that of HIV-negative women. CONCLUSIONS: Research is needed to clarify etiological relationships and the role of human papillomavirus in the causal pathway of the observed association. Meanwhile, available data are sufficient to encourage regular Papanicolaou's smear screening of HIV-infected women, and HIV testing and counseling of women with CN considered at risk for HIV infection. 相似文献
103.
锌酞菁脂质体光动力作用引起小鼠肿瘤的细胞程序性死亡 总被引:4,自引:1,他引:3
电镜观察了锌酞菁脂质体光动力作用引起小鼠MS-2纤维肉瘤的形态学变化。发现其作用很强,并对肿瘤细胞有明显的直接影响。肿瘤细胞的结构表现出明显的程序性细胞死亡(apoptosis,programmedceldeath)的特点:胞核染色质凝聚边集、核固缩、核破裂、染色质凝块流失、胞质内吞噬现象、胞膜表面肿胀粗钝的胞突形成、细胞碎裂等。加深了对锌酞菁脂质体光敏作用机理的认识,但其详细的发生机制和调节途径有待阐明。 相似文献
104.
Patients infected with influenza A virus (IAV) are at increased risk for bacterial superinfections, and this occurs in association with depressed polymorphonuclear leukocyte (PMNL) function. Recently, we reported that in vitro exposure of human PMNL to granulocyte-macrophage colony-stimulating factor (GM-CSF) reverses IAV-induced cell dysfunction. The present study used an established animal model of IAV infection to examine whether G-CSF and/or GM-CSF can overcome IAV- induced PMNL dysfunction and thereby prevent secondary infections. Preliminary studies determined a dosing schedule of these cytokines that caused significant priming of chinchilla PMNL. In subsequent studies, animals were inoculated intranasally with IAV (day 1) followed 3 days later by Streptococcus pneumoniae, and administered daily intraperitoneal injections with a cytokine or placebo on days 3 through 9. Animals had blood obtained on multiple occasions for PMNL studies, and were followed-up for evidence of pneumococcal disease. Both cytokines caused significant priming of the PMNL chemiluminescence response and this was associated with reversal of the IAV-induced PMNL dysfunction. However, neither cytokine decreased the incidence of pneumococcal disease. 相似文献
105.
106.
Mueller NT Noone AM Luta G Wallington SF Huerta EE Mandelblatt JS;Latin American Cancer Research Coalition 《Journal of immigrant and minority health / Center for Minority Public Health》2012,14(1):183-188
We report on information channels associated with awareness about human papillomavirus (HPV) among immigrant Central and South
American Latinos. We conducted a survey of 1,334 Latino ≥ 21 years attending safety-net clinics in 2007–2008. Logistic regression
analyses evaluated associations with HPV awareness. Forty-eight percent were aware of HPV infection and 40% were aware of
the vaccine. Spanish television (38%) and providers (23%) were the primary HPV information sources. Infection awareness was
associated with internet use (OR 1.47; 95% CI 1.10–1.96) and self-efficacy to find health information (OR 1.19; 95% CI 1.08–1.30).
Vaccine awareness was associated with media use for health information (OR 1.27; 95% CI 1.09–1.49) and internet use (OR 1.59;
95% CI 1.18–2.13). Although Spanish television has reached this low HPV awareness group, there may be missed opportunities
for education by providers. Television and the internet may also be effective channels for future interventions. 相似文献
107.
Wallington SF Luta G Noone AM Caicedo L Lopez-Class M Sheppard V Spencer C Mandelblatt J 《Journal of community health》2012,37(2):335-343
Clinical trials are considered the gold standard of evidence about the efficacy of cancer prevention, early detection, and
treatment interventions. A paucity of data exists on determinants of clinical trial participation in the growing US Latino
population despite poor cancer outcomes in this group. This study seeks to describe correlates of awareness of and willingness
to participate in clinical trials among largely Central, North, and South American Latinos using safety-net clinics. Between
June 2007 and November 2008, we conducted an interviewer-administered, Spanish-language cross-sectional survey (n = 944). Logistic regression was used to assess effects of health information sources and psychosocial variables on awareness
of and intention to participate in clinical trials. Analyses were completed in spring 2010. While only 48% knew what a clinical
trial was, when explained, 65% indicated a willingness to participate. Providers were the most common source of health information.
Use of Internet for health information, trust in health information, and higher education each independently increased the
odds of clinical trial awareness, but obtaining information from providers did not. Contacting the Cancer Information Service
and psychosocial factors were each independently associated with intent to join a clinical trial, while demographic factors
were not. Information channels such as the Internet may be effective in conveying clinical trial information to Latinos. Providers
being cited as the most common source of health information but not being associated with knowledge about or intent to participate
in trials suggests a missed opportunity for communication to this population. 相似文献
108.
This study utilized data from an ongoing randomized controlled trial to compare a culturally tailored video promoting positive attitudes toward mammography among Chinese immigrant women to a linguistically appropriate generic video and print media. Intervention development was guided by the Health Belief Model. Five hundred and ninety-two immigrant Chinese Americans from the metropolitan Washington, DC, and New York City areas completed telephone interviews before and after intervention. Changes in knowledge, Eastern views of health care (fatalism and self-care), health beliefs (perceived susceptibility, severity, benefits and barriers) and screening intentions were measured. Results showed that both videos improved screening knowledge, modified Eastern views of health care, reduced perceived barriers and increased screening intentions relative to print media (all P < 0.05). The generic video increased screening intention twice as much as the cultural video, although subgroup analysis showed the increase was only significant in women aged 50-64 years. Only Eastern views of health care were negatively associated with screening intentions after adjusting for all baseline covariates. These data suggest that a theoretically guided linguistically appropriate video that targets women from various ethnic groups is as efficacious in modifying attitudes toward mammography screening as a video that is exclusively tailored for Chinese immigrant women. 相似文献
109.
Studies on levamisole--induced agranulocytosis 总被引:1,自引:0,他引:1
Thompson JS; Herbick JM; Klassen LW; Severson CD; Overlin VL; Blaschke JW; Silverman MA; Vogel CL 《Blood》1980,56(3):388-396
Widespread clinical trials of leavo-tetramisole (levamisole) as an immunopotentiating agent in rheumatoid arthritis, metastatic carcinoma, and immunodeficiency states have been complicated by agranulocytosis (AGC) in 2.5%-13% of patients. Other than a relationship with prolonged high dosage, very little is known regarding the pathogenesis of levamisole-induced AGC. Whereas leukoagglutination was negative, fluorochromatic microgranulocytotoxicity (GCY) tests were positive with serum from 10 of 10 acutely neutropenic patients. The antibody was IgM, reacted with 100% of unrelated granulocytes, but not with T or B lymphocytes. Some sera also reacted with monocytes and the myeloid cell line, K-562. Tests for antigen-antibody complexes or cold autoantibodies were negative. Although clinical evidence strongly suggests a haptene (drug) mechanism, in vitro mixing experiments were also negative. An alternative choice parallels the model of aldomet- induced Coombs'-positive hemolytic anemia. Finally, GCY first became positive 2-3 mo prior to the onset of AGC on two patients, suggesting the possibility of identifying those at risk well before the onset of neutropenia. 相似文献
110.
Sawaya GF Grady D Kerlikowske K Valleur JL Barnabei VM Bass K Snyder TE Pickar JH Agarwal SK Mandelblatt J 《Annals of internal medicine》2000,133(12):942-950
BACKGROUND: The benefits and risks of performing annual cervical smears on postmenopausal women are not well defined. The independent effect of hormone replacement therapy on development of cytologic abnormalities is unknown. OBJECTIVE: To determine the positive predictive value of cervical smears in previously screened postmenopausal women and to determine the effect of oral estrogen plus progestin on incident cervical cytologic abnormalities. DESIGN: Prospective cohort study (incidence) and randomized, double-blind, placebo-controlled trial (hormone therapy). SETTING: 20 U.S. outpatient and community clinical centers. PARTICIPANTS: 2561 women with a uterus and normal cytologic characteristics at baseline. INTERVENTIONS: Annual smears; oral conjugated equine estrogens, 0. 625 mg/d, plus medroxyprogesterone acetate, 2.5 mg/d, or identical placebo. MEASUREMENTS: Incident cytologic abnormalities (atypical squamous cells of undetermined significance, atypical glandular cells of undetermined significance, low-grade squamous epithelial lesion, and high-grade squamous epithelial lesion) and final histologic diagnoses. RESULTS: The incidence of new cytologic abnormalities in the 2 years following a normal smear was 110 per 4895 person-years (23 per 1000 person-years [95% CI, 18 to 27 per 1000 person-years]). Among the 103 women with known histologic diagnoses, one had mild to moderate dysplasia. The positive predictive value of any smear abnormality identified 1 year after a normal smear, therefore, was 0% (CI, 0% to 5.0%) (0 of 78 women); the positive predictive value of abnormalities found within 2 years was 0.9% (CI, 0.0% to 3.0%) (1 of 110 women). In hormone-treated compared with non-hormone-treated women, the incidence of cytologic abnormalities was nonsignificantly higher (relative hazard, 1.36 [CI, 0.93 to 1.99]), largely because of a nonsignificant 58% greater incidence of atypical squamous cells of undetermined significance (relative hazard, 1.58 [CI, 0.99 to 2.52]). CONCLUSIONS: Because of a poor positive predictive value, cervical smears should not be performed within 2 years of normal cytologic results in postmenopausal women. Therapy with oral estrogen plus progestin does not significantly affect the incidence of cytologic abnormalities. 相似文献