全文获取类型
收费全文 | 5409篇 |
免费 | 558篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 133篇 |
妇产科学 | 97篇 |
基础医学 | 526篇 |
口腔科学 | 99篇 |
临床医学 | 615篇 |
内科学 | 976篇 |
皮肤病学 | 128篇 |
神经病学 | 423篇 |
特种医学 | 258篇 |
外科学 | 756篇 |
综合类 | 184篇 |
现状与发展 | 30篇 |
一般理论 | 5篇 |
预防医学 | 704篇 |
眼科学 | 111篇 |
药学 | 279篇 |
中国医学 | 53篇 |
肿瘤学 | 570篇 |
出版年
2023年 | 191篇 |
2021年 | 61篇 |
2020年 | 73篇 |
2019年 | 64篇 |
2018年 | 112篇 |
2017年 | 86篇 |
2016年 | 95篇 |
2015年 | 128篇 |
2014年 | 160篇 |
2013年 | 199篇 |
2012年 | 240篇 |
2011年 | 217篇 |
2010年 | 186篇 |
2009年 | 173篇 |
2008年 | 218篇 |
2007年 | 246篇 |
2006年 | 227篇 |
2005年 | 207篇 |
2004年 | 173篇 |
2003年 | 191篇 |
2002年 | 175篇 |
2001年 | 159篇 |
2000年 | 172篇 |
1999年 | 147篇 |
1998年 | 87篇 |
1997年 | 94篇 |
1996年 | 83篇 |
1995年 | 78篇 |
1994年 | 70篇 |
1993年 | 84篇 |
1992年 | 123篇 |
1991年 | 101篇 |
1990年 | 98篇 |
1989年 | 103篇 |
1988年 | 101篇 |
1987年 | 97篇 |
1986年 | 90篇 |
1985年 | 90篇 |
1984年 | 69篇 |
1983年 | 49篇 |
1982年 | 39篇 |
1981年 | 42篇 |
1980年 | 45篇 |
1979年 | 45篇 |
1977年 | 37篇 |
1976年 | 46篇 |
1975年 | 36篇 |
1974年 | 43篇 |
1973年 | 39篇 |
1972年 | 31篇 |
排序方式: 共有5990条查询结果,搜索用时 15 毫秒
51.
Ann W. Hsing Joseph K. McLaughlin Pierluigi Cocco Harvey T. Co Chien Joseph F. Fraumeni Jr. 《Cancer causes & control : CCC》1998,9(3):269-275
Objectives: The etiology of male breast cancer is obscure, although an excess risk has been associated with Klinefelter syndrome, testicular disorders, benign breast disease including gynecomastia, use of exogenous estrogens, radiation, and a family history of male or female breast cancer. We conducted a case-control study to investigate risk factors further for breast cancer in men.Methods: Based on data from the 1986 National (United States) Mortality Followback Survey (NMFS) of almost 20,000 deceased adults (age 25 years or over), we compared information obtained from next-of-kin interviews of 178 men who died of breast cancer with that of 512 male controls who died of other causes. Information was obtained on selected demographic and other factors, including diet, exercise, occupation, height and weight, and use of tobacco and alcohol.Results: Increased risks were found for men who were described by their next-of-kin as very overweight (odds ratio [OR] = 2.3, 95 percent confidence interval [CI] = 1.1-5.0). The risks associated with the three upper quartiles of body mass index (BMI) (wt/ht2) were 1.3, 1.6, and 2.3, respectively, with a significant dose-response relationship (P < 0.01). An excess risk was also associated with limited exercise (OR = 1.3, CI = 0.8-2.0). Consumption of red meat was associated with an increased risk, and consumption of fruits and vegetables with a decreased risk, although the trends were not significant. No association was found for tobacco or alcohol use, but an excess risk was associated with higher levels of socioeconomic status (SES) (OR = 1.8, CI = 1.1-3.0).Conclusions: Our study suggests that obesity increases the risk of male breast cancer, possibly through hormonal mechanisms, while dietary factors, physical activity, and SES indicators also deserve further investigation. Cancer Causes andd Control 1998, 269-275 相似文献
52.
An adenoviral vector expressing the glucose transporter protects cultured striatal neurons from 3-nitropropionic acid 总被引:2,自引:0,他引:2
Considerable interest has focused on the possibility of using gene transfer techniques to introduce protective genes into neurons around the time of necrotic insults. We have previously used herpes simplex virus amplicon vectors to overexpress the rat brain glucose transporter, Glut-1 (GT), and have shown it to protect against a variety of necrotic insults both in vitro and in vivo, as well as to buffer neurons from the steps thought to mediate necrotic injury. It is critical to show the specificity of the effects of any such transgene overexpression, in order to show that protection arises from the transgene delivered, rather than from the vector delivery system itself. As such, we tested the protective potential of GT overexpression driven, in this case, by an adenoviral vector, against a novel insult, namely exposure of primary striatal cultures to the metabolic poison, 3-nitropropionic acid (3NP). We observed that GT overexpression buffered neurons from neurotoxicity induced by 3NP. 相似文献
53.
54.
David C Miller Martin G Sanda Rodney L Dunn James E Montie Hector Pimentel Howard M Sandler William P McLaughlin John T Wei 《Journal of clinical oncology》2005,23(12):2772-2780
PURPOSE: We sought to elucidate long-term changes in health-related quality-of-life (HRQOL) outcomes by prospectively re-evaluating a well-characterized cohort of prostate cancer (PC) survivors 4 to 8 years after primary treatment. PATIENTS AND METHODS: Patients who had been evaluated previously at a median of 2.6 years after radical prostatectomy (RP), external radiation (three-dimensional conformal radiation therapy [3-D CRT]), or brachytherapy (BT) were recontacted at a median of 6.2 years after treatment. The clinical relevance of long-term HRQOL impairment among survivors was established by comparison with controls of similar age. Factors associated with HRQOL changes during this interval were evaluated. RESULTS: Of the 964 eligible men, 709 (73.5%) completed measurable questionnaires. In four domains (urinary irritative-obstructive, urinary incontinence, bowel, and sexual), significant HRQOL differences were detected for at least one of the therapy groups, compared with controls (all P < .05). During the 4-year interval, significant improvement was observed for the urinary irritative-obstructive (P < .0001) and bowel (P < .0001) domains among BT patients, whereas urinary incontinence HRQOL worsened for both the BT (P = .0017) and 3-D CRT (P = .0008) treatment groups. Overall sexual HRQOL deteriorated for the 3-D CRT cohort (P = .0017), as well as for controls (P = .0136). Among RP patients, significant HRQOL changes were not observed. CONCLUSION: During a 4-year interval from earlier to longer-term phases of PC treatment survivorship, sexual, urinary, and bowel dysfunction remain significant concerns among early-stage PC treatment survivors, compared with control men. Although postprostatectomy HRQOL remains relatively stable during this interval, disease-specific HRQOL continues to evolve among men treated with BT and 3-D CRT. 相似文献
55.
56.
57.
McLaughlin JL 《Journal of natural products》2008,71(7):1311-1321
Extracts of paw paw ( Asimina triloba, Annonaceae) are among the most potent of the 3500 species of higher plants screened for bioactive compounds in our laboratories at Purdue University. The paw paw is a small tree native to eastern North America; its edible fruits (sometimes referred to as "Indiana Bananas") have nurtured mankind for centuries. Activity-directed fractionation of the paw paw extracts, using the brine shrimp lethality bioassay, led to the isolation and molecular characterization of over 50 unique annonaceous acetogenins. Fractionation of extracts from related species resulted in the identification of over 150 additional acetogenins. The annonaceous acetogenins are derivatives of long-chain (C32 or C34) fatty acids. They are potent inhibitors of mitochondrial (complex I) as well as cytoplasmic (anaerobic) production of adenosine triphosphate (ATP) and the related nucleotides. The powerful cytotoxicity, in vivo antitumor, pesticidal, antimalarial, anthelmintic, piscicidal, antiviral, and antimicrobial effects indicated a myriad of potentially useful applications. Commercial development of these compounds uses natural mixtures of active components, incorporated into pesticidal, topical, and dietary supplement products. Successful applications and commercial products include a shampoo, highly effective in treating infestations of head lice, fleas, and ticks; a series of pesticidal sprays, which protects host plants against a diversity of pests; and an ointment for treatment of oral herpes (HSV-1) and other skin afflictions. The extract (in capsule form) enhances a mixture of natural anthelmintics. In addition, an encapsulated extract has been effectively used by certain cancer patients as a botanical supplement product. 相似文献
58.
Blythe A. Layton Devrim Kaya Christine Kelly Kenneth J. Williamson Dana Alegre Silke M. Bachhuber Peter G. Banwarth Jeffrey W. Bethel Katherine Carter Benjamin D. Dalziel Mark Dasenko Matthew Geniza Andrea George Anne-Marie Girard Roy Haggerty Kathryn A. Higley Denise M. Hynes Jane Lubchenco Katherine R. McLaughlin F. Javier Nieto Aslan Noakes Matthew Peterson Adriana D. Piemonti Justin L. Sanders Brett M. Tyler Tyler S. Radniecki 《Environmental health perspectives》2022,130(6)
Background: Positive correlations have been reported between wastewater SARS-CoV-2 concentrations and a community’s burden of infection, disease or both. However, previous studies mostly compared wastewater to clinical case counts or nonrepresentative convenience samples, limiting their quantitative potential.Objectives: This study examined whether wastewater SARS-CoV-2 concentrations could provide better estimations for SARS-CoV-2 community prevalence than reported cases of COVID-19. In addition, this study tested whether wastewater-based epidemiology methods could identify neighborhood-level COVID-19 hotspots and SARS-CoV-2 variants.Methods: Community SARS-CoV-2 prevalence was estimated from eight randomized door-to-door nasal swab sampling events in six Oregon communities of disparate size, location, and demography over a 10-month period. Simultaneously, wastewater SARS-CoV-2 concentrations were quantified at each community’s wastewater treatment plant and from 22 Newport, Oregon, neighborhoods. SARS-CoV-2 RNA was sequenced from all positive wastewater and nasal swab samples. Clinically reported case counts were obtained from the Oregon Health Authority.Results: Estimated community SARS-CoV-2 prevalence ranged from 8 to 1,687/10,000 persons. Community wastewater SARS-CoV-2 concentrations ranged from 2.9 to gene copies per liter. Wastewater SARS-CoV-2 concentrations were more highly correlated (Pearson’s ; ) with community prevalence than were clinically reported cases of COVID-19 (Pearson’s ; ). Monte Carlo simulations indicated that wastewater SARS-CoV-2 concentrations were significantly better than clinically reported cases at estimating prevalence (). In addition, wastewater analyses determined neighborhood-level COVID-19 hot spots and identified SARS-CoV-2 variants (B.1 and B.1.399) at the neighborhood and city scales.Discussion: The greater reliability of wastewater SARS-CoV-2 concentrations over clinically reported case counts was likely due to systematic biases that affect reported case counts, including variations in access to testing and underreporting of asymptomatic cases. With these advantages, combined with scalability and low costs, wastewater-based epidemiology can be a key component in public health surveillance of COVID-19 and other communicable infections. https://doi.org/10.1289/ EHP10289相似文献
59.
60.
Jessica Mangundayao T. F. McLaughlin Randy Lee Williams Ellie Toone 《Journal of developmental and physical disabilities》2013,25(4):461-473
The purpose of this study was to evaluate the effectiveness of the DI Flashcard system for teaching preliminary mathematic skills to three preschool students. The participants attended a self-contained special education preschool. All three participants’ eligibility category was “developmentally delayed”. A concurrent multiple baseline design across three sets (colors, shapes, and numerals) was use to evaluate the effectiveness of the DI flashcard system. The results indicated that all three participants showed an increase in their performance when DI flashcards were in effect. However, the amount of improvement varied for each participant. The importance of employing evidence-based procedures to teach skills to preschool students with developmental delays was outlined. 相似文献