全文获取类型
收费全文 | 20382篇 |
免费 | 1312篇 |
国内免费 | 72篇 |
专业分类
耳鼻咽喉 | 233篇 |
儿科学 | 735篇 |
妇产科学 | 583篇 |
基础医学 | 2348篇 |
口腔科学 | 250篇 |
临床医学 | 3523篇 |
内科学 | 3489篇 |
皮肤病学 | 203篇 |
神经病学 | 1947篇 |
特种医学 | 313篇 |
外科学 | 1642篇 |
综合类 | 204篇 |
一般理论 | 85篇 |
预防医学 | 3121篇 |
眼科学 | 709篇 |
药学 | 1020篇 |
中国医学 | 11篇 |
肿瘤学 | 1350篇 |
出版年
2023年 | 81篇 |
2022年 | 134篇 |
2021年 | 293篇 |
2020年 | 212篇 |
2019年 | 359篇 |
2018年 | 412篇 |
2017年 | 315篇 |
2016年 | 368篇 |
2015年 | 447篇 |
2014年 | 589篇 |
2013年 | 1022篇 |
2012年 | 1395篇 |
2011年 | 1467篇 |
2010年 | 810篇 |
2009年 | 694篇 |
2008年 | 1315篇 |
2007年 | 1523篇 |
2006年 | 1488篇 |
2005年 | 1479篇 |
2004年 | 1420篇 |
2003年 | 1318篇 |
2002年 | 1268篇 |
2001年 | 178篇 |
2000年 | 129篇 |
1999年 | 191篇 |
1998年 | 275篇 |
1997年 | 223篇 |
1996年 | 188篇 |
1995年 | 163篇 |
1994年 | 177篇 |
1993年 | 147篇 |
1992年 | 100篇 |
1991年 | 107篇 |
1990年 | 93篇 |
1989年 | 82篇 |
1988年 | 73篇 |
1987年 | 77篇 |
1986年 | 72篇 |
1985年 | 73篇 |
1984年 | 101篇 |
1983年 | 99篇 |
1982年 | 115篇 |
1981年 | 126篇 |
1980年 | 107篇 |
1979年 | 64篇 |
1978年 | 58篇 |
1977年 | 56篇 |
1976年 | 47篇 |
1975年 | 44篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Dr. Mary S. Brady MD Carol F. Garfein MBA Jeanne A. Petrek MD Murray F. Brennan MD 《Annals of surgical oncology》1994,1(1):66-72
Background: Many patients treated for breast cancer with radiotherapy will survive their disease and be at risk for treatment-related sarcoma for many years.
Methods: In order to identify patients with post-treatment sarcoma and define this disease, we examined the records of 99 patients treated for sarcoma with a history of antecedent breast carcinoma. Of these patients, 51 were felt to have a sarcoma unrelated to breast cancer treatment and 48 were felt to have a treatment-related sarcoma (secondary to lymphedema and/or radiation).
Results: Lymphangiosarcoma of the extremity was the most common histologic subtype of post-treatment sarcoma, accounting for 22 of 48 cases (46%). Twenty-six patients (54%) developed nonlymphangiosarcoma post-treatment sarcoma; all of these were radiation-associated sarcomas. The median latency interval between the diagnosis of breast cancer and the development of sarcoma was 11 years (range 4–44) and was not different between the two groups. However, patients with nonlymphangiosarcoma were significantly younger when diagnosed with breast cancer than were those with lymphangiosarcoma of the extremity (median 43 vs. 51 years, p<0.001). The survival of all 48 patients was poor: 5-year survival was 29%. Five-year survival of patients with other types of post-treatment sarcoma was just as poor as those with lymphangiosarcoma of the extremity (30% vs. 28%, p=0.98).
Conclusions: Patients who develop sarcoma after treatment for breast cancer have a poor prognosis whether it occurs as Stewart-Treves syndrome or other types of post-treatment sarcoma. Younger patients may be at higher risk than are older patients for the development of nonlymphangiosarcoma post-treatment sarcoma.Presented at the 46th Annual Cancer Symposium of the Society of Surgical Oncology, Los Angeles, March 18–21, 1993. 相似文献
42.
Ana P Martinez-Donate Melbourne F Hovell Elaine J Blumberg Jennifer A Zellner Carol L Sipan Audrey M Shillington Claudia Carrizosa 《AIDS education and prevention》2004,16(2):172-186
Adolescents are at increasing risk for HIV infection in Mexico. Research on gender differences in risk behaviors and determinants is needed to develop effective HIV prevention interventions targeting Mexican adolescents. This study examined gender differences in the likelihood of unprotected sex and theoretical correlates among high school students in the border city of Tijuana. Three hundred seventy high-school students completed a face-to-face interview and a self-administered survey. Differences in sexual initiation, condom use, intentions to use condoms in the future, and attitudes towards condoms in this population were assessed. Although male students initiated sexual practices earlier than females, females were more likely to have unprotected sex. Females perceived themselves as more likely to avoid unprotected sex in the future and held more favorable attitudes about condoms. The results suggest that stereotypical gender roles and communication barriers place Tijuana female high school students at higher risk for HIV infection than their male peers. 相似文献
43.
44.
Granulysin: A Novel Host Defense Molecule 总被引:5,自引:0,他引:5
Granulysin is a novel cationic molecule present in the granules of cytotoxic T lymphocytes and natural killer cells. Cytotoxic T lymphocytes have long been associated with graft destruction in transplant rejection. Recent studies implicate granulysin in cell-mediated cytotoxicity, chemoattraction, immune activation and as a potential diagnostic biomarker for transplant rejection. 相似文献
45.
Genevieve Fridlund Dunton Carol K. Whalen Larry D. Jamner Josh N. Floro 《Annals of behavioral medicine》2007,34(2):144-153
BACKGROUND: Research has sought to understand how environmental factors influence adolescent physical activity, yet little is known about where and with whom adolescents are physically active. PURPOSE: This study used electronic ecological momentary assessment (e.EMA) to map the social and physical contexts of exercise and walking across adolescence. Differences in physical activity contexts by gender, grade in school, day of the week, and season were examined. METHODS: Twice a year between 9th and 12th grade, 502 adolescents (51% female) of mixed ethnicity (55% White) participated in 4-day e.EMA intervals (Thursday-Sunday) where their primary activity (e.g., exercise, TV, homework), social company (e.g., friends, family, class), and physical location (e.g., home, school, outdoors) were assessed every 30 (+/-10) min during waking hours. RESULTS: Overall, greater proportions of exercise and walking were reported with friends, outdoors, and at school. However, boys were more likely to report exercising and walking in outdoor locations than girls. Exercising with classmates, family, and at school decreased across high school. Walking with family, friends, and outdoors also decreased. On weekdays compared to weekends, students reported a greater proportion of their exercise and walking at school. Students were more likely to report exercising and walking outdoors in the fall and the spring than in the winter. CONCLUSION: e.EMA showed that the social and physical contexts of adolescent exercise and walking vary as a function of gender, grade in school, day of the week, and season. Understanding the contexts of physical activity during the high school years can be helpful in designing interventions during adolescence. 相似文献
46.
Van Buskirk Glenn A. González Mario A. Shah Vinod P. Barnhardt Scott Barrett Colin Berge Stephen Cleary Gary Chan Keith Flynn Gordon Foster Thomas Gale Robert Garrison Raymond Gochnour Scott Gotto Amanda Govil Sharad Gray Vivian A. Hammar James Harder Samuel Hoiberg Charles Hussain Ajaz Karp Carol Llanos Hector Mantelle Juan Noonan Patrick Swanson David Zerbe Horst 《Pharmaceutical research》1997,14(7):848-852
Pharmaceutical Research - 相似文献
47.
48.
Carol A. Sawka Kathleen I. Pritchard Wendy Shelley Gerrit DeBoer Alexander H.G. Paterson J. William Meakin Donald J.A. Sutherland 《Breast cancer research and treatment》1997,43(3):211-215
Background: The outcome of breast cancer is usuallydetermined by multiple factors. Serum tumor necrosis factoralpha concentration has been found to be increasedin the circulation of patients with malignancy. Thisstudy was designed with the aim to investigateany correlation between the serum tumor necrosis factoralpha and the clinicopathological fetures and furthermore evaluatethe prognostic significance of serum tumor necrosis factoralpha concentration in breast cancer. Methods: Forty consecutivepatients with invasive breast cancer undergoing modified radicalmastectomy were prospectively included and evaluated. Venous bloodsamples were collected before the surgery. Sera wereobtained by centrifugation, and stored at – 70°C until assayed. The control group consisted 30healthy, age-matched subjects. Serum concentrations of tumor necrosisfactor alpha were measured by the quantitative sandwichenzyme immunoassay technique. The data on tumor size,age, estrogen receptor status, lymph node status andTNM staging were reviewed and recorded.Results: The mean value of serum tumor necrosis factor alphain patients with invasive breast cancer was 1.47± 0.58 pg/ml and that of the controlgroup was 0.98 ± 0.37 pg/ml, and thedifference was significant (P < 0.01). With univariableanalysis, patients with maximum tumor size of 5cm or larger (P=0.03), more advancedTNM staging (P < 0.01); and more advancedlymph node status (P < 0.01) were shownto have significantly higher serum concentrations of tumornecrosis factor alpha. However, with multivariable analysis, TNMstaging appeared as the only independent factor (P< 0.01) predicting the significant, higher serum concentrationsof tumor necrosis factor alpha. Conclusion: Preoperative evaluationof serum tumor necrosis factor alpha concentrations maybe a valuable parameter for reflecting the severityof staging for invasive breast cancer. 相似文献
49.
Is commercial alcohol availability related to adolescent alcohol sources and alcohol use? Findings from a multi-level study. 总被引:1,自引:1,他引:0
Mallie J Paschall Joel W Grube Carol Black Christopher L Ringwalt 《The Journal of adolescent health》2007,41(2):168-174
PURPOSE: To examine whether compliance with underage sales laws by licensed retail establishments is related to underage use of commercial and social alcohol sources, perceived ease of obtaining alcohol, and alcohol use. METHODS: In 2005, alcohol purchase surveys were conducted at 403 off-premise licensed retail establishments in 43 Oregon school districts. A survey also was administered to 3,332 11th graders in the districts. Multi-level logistic regression analyses were used to examine relationships between the school district-level alcohol sales rate and students' use of commercial and social alcohol sources, perceived ease of obtaining alcohol, past-30-day alcohol use, and heavy drinking. RESULTS: The school district-level alcohol sales rate was positively related to students' use of commercial alcohol sources and perceived alcohol availability, but was not directly associated with use of social alcohol sources and drinking behaviors. Additional analyses indicated stronger associations between drinking behaviors and use of social alcohol sources relative to other predictors. These analyses also provided support for an indirect association between the school district-level alcohol sales rate and alcohol use behaviors. CONCLUSIONS: Compliance with underage alcohol sales laws by licensed retail establishments may affect underage alcohol use indirectly, through its effect on underage use of commercial alcohol sources and perceived ease of obtaining alcohol. However, use of social alcohol sources is more strongly related to underage drinking than use of commercial alcohol sources and perceived ease of obtaining alcohol. 相似文献
50.