全文获取类型
收费全文 | 190878篇 |
免费 | 2157篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 1282篇 |
儿科学 | 7346篇 |
妇产科学 | 3430篇 |
基础医学 | 18332篇 |
口腔科学 | 1714篇 |
临床医学 | 14604篇 |
内科学 | 33713篇 |
皮肤病学 | 835篇 |
神经病学 | 18051篇 |
特种医学 | 9234篇 |
外科学 | 30342篇 |
综合类 | 2537篇 |
一般理论 | 15篇 |
预防医学 | 20207篇 |
眼科学 | 3083篇 |
药学 | 10319篇 |
中国医学 | 637篇 |
肿瘤学 | 17386篇 |
出版年
2023年 | 137篇 |
2022年 | 234篇 |
2021年 | 564篇 |
2020年 | 348篇 |
2019年 | 535篇 |
2018年 | 22366篇 |
2017年 | 17687篇 |
2016年 | 19866篇 |
2015年 | 1319篇 |
2014年 | 1371篇 |
2013年 | 1640篇 |
2012年 | 8113篇 |
2011年 | 22254篇 |
2010年 | 19384篇 |
2009年 | 12079篇 |
2008年 | 20451篇 |
2007年 | 22695篇 |
2006年 | 1520篇 |
2005年 | 3039篇 |
2004年 | 4154篇 |
2003年 | 5093篇 |
2002年 | 3139篇 |
2001年 | 396篇 |
2000年 | 527篇 |
1999年 | 303篇 |
1998年 | 351篇 |
1997年 | 301篇 |
1996年 | 169篇 |
1995年 | 187篇 |
1994年 | 168篇 |
1993年 | 122篇 |
1992年 | 139篇 |
1991年 | 206篇 |
1990年 | 215篇 |
1989年 | 166篇 |
1988年 | 127篇 |
1987年 | 109篇 |
1986年 | 110篇 |
1985年 | 121篇 |
1984年 | 86篇 |
1983年 | 79篇 |
1982年 | 76篇 |
1981年 | 55篇 |
1980年 | 96篇 |
1979年 | 53篇 |
1974年 | 55篇 |
1970年 | 49篇 |
1969年 | 50篇 |
1938年 | 60篇 |
1932年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
993.
Laser resurfacing is exciting "futuristic" surgery. The CO2 laser resurfaces using different parameters from the Er:YAG laser. When the surgeon understands these parameters, each laser can be used as a powerful tool for specific clinical applications. The Er:YAG laser was initially thought to be for the patient who has minimal skin laxity, but who desires skin resurfacing and needs a speedy return to social life. The CO2 laser has typically been thought to work best for skin laxity as well as rhytids, at the price of a longer recovery period. As the hardware and techniques continue to evolve, the differences between the clinical scope addressed by each laser diminishes. Both lasers deserve a place in the plastic surgeon's armamentarium. This new combination CO2/Er:YAG technique is intriguing and deserves further in-depth investigation. Laser resurfacing is not a cureall, but, when applied appropriately, it is an excellent tool that the plastic surgeon can use for skin rejuvenation. 相似文献
994.
Relation between prepublication release of clinical trial results and the practice of carotid endarterectomy 总被引:2,自引:2,他引:0
Context Little is known about how clinical practice is affected by disseminating results of clinical trials prior to publication in peer-reviewed journals. Objective To determine whether prepublication release of carotid endarterectomy (CEA) trial results via National Institutes of Health Clinical Alerts was associated with prompt changes in patient care that were consistent with the new medical evidence. Design, Setting, and Patients Longitudinal data series analysis using acute care hospital discharge data from the Healthcare Cost and Utilization Project for patients who had CEA performed in acute care hospitals in 7 states (New York, California, Pennsylvania, Florida, Colorado, Illinois, and Wisconsin). The trials were the North American Symptomatic Carotid Endarterectomy Trial (NASCET clinical alert released February 1991) and the Asymptomatic Carotid Atherosclerosis Study (ACAS clinical alert released September 1994). Main Outcome Measure Carotid endarterectomy rate during each month from 1989 (2 years before the NASCET clinical alert) to 1996 (2 years after the ACAS clinical alert), adjusted for age and sex. Because both trials were limited to patients 80 years or younger in hospitals with low mortality, we also stratified CEA rates by patient age and hospital mortality rate. Results From 1989 through 1996, 272,849 CEAs were performed in the acute care hospitals in these 7 states, with the annual number increasing from 22,300 to 51,495. After the NASCET clinical alert, the adjusted CEA rate increased 3.4% per month (95% confidence interval [CI], 1.6%-5.3%) during the following 6 months and then increased 0.5% per month (95% CI, 0.2%-0.8%; P<.04) after journal publication of the NASCET study. After the ACAS clinical alert, the CEA rate increased 7.3% per month (95% CI, 6.0%-8.5%) during the following 7 months and then decreased by 0.44% per month (95% CI, -0.86% to -0.0002%; P<.04) after journal publication of the ACAS study. After the ACAS clinical alert, the CEA rate increased more in patients aged 80 years or older than in younger patients; whereas, after journal publication of ACAS, the CEA rate decreased more rapidly in the older population. The overall proportion of CEAs performed in low-mortality hospitals did not change substantially after release of the clinical alerts or after journal publication. Conclusion In this study, prepublication dissemination of CEA trial results with clinical alerts was associated with prompt and substantial changes in medical practice, but the observed changes suggest that the results were extrapolated to patients and settings not directly supported by the trials. 相似文献
995.
996.
997.
998.
Wei Yue Steven J. Santner Shigeru Masamura Ji-Ping Wang Laurence M. Demers Christopher Hamilton Richard J. Santen 《Breast cancer research and treatment》1998,49(1):S1-S7
Estradiol stimulates the growth of breast tumor cells in both pre- and post menopausal women. Following the menopause, the levels of estradiol in breast tumor tissues are similar to those from tumors obtained prior to cessation of ovarian function, even though plasma estrogen levels are 10–50 fold lower in post- than in premenopausal women. These observations suggested the possibility of enhanced estradiol uptake from plasma or in situ synthesis in post-menopausal women. We systematically studied these possibilities in a series of model systems. Initially we demonstrated a very high affinity estradiol binding site in tissues from castrated rats. Enhanced uptake occurred under conditions of low plasma estrogen levels when compared to animals with higher estradiol levels. In situ synthesis also occurred both through the sulfatase and aromatase pathways. In further studies, we compared uptake from plasma with in situ synthesis via aromatase in a nude mouse model. Under the conditions utilized, in situ synthesis resulted in much higher tissue estradiol levels and tumor growth rates than did uptake from plasma. During these studies we demonstrated that tumors deprived of estradiol developed mechanisms rendering them more sensitive to estrogen. This involved the ability of cells to adapt to estradiol deprivation to allow them to be responsive to four log lower amounts of estrogen than when studied under wild type conditions. In addition, cells adapted by increasing their level of aromatase and thus developing the capability to become more sensitive to estrogen precursors. Taken together, these studies demonstrate that breast cancer tissue is highly plastic and can adapt to conditions of estrogen deprivation via a variety of mechanisms. 相似文献
999.
1000.
Anne M. Buison Michael A. Pellizzon Kathryn E. Brogan Maria J. Barnes K.-L. Catherine Jen 《Nutrition Research》2005,25(12):1097-1108
The present study tested the hypothesis that weight cycling (WC, repeated weight gain and loss) increases the tumorigenesis in rats exposed to carcinogen. Female Wistar rats consumed a high-fat diet (35% weight per weight) and were divided: (1) ad lib–fed rats that were treated with 7,12-dimethylbenzyl(1)anthracene (DMBA, 2 mg) at 55 days of age (AL-DMBA); (2) WC rats that were treated with DMBA (WC-DMBA); and (3) vehicle-treated WC rats (WC-VEH). In this study, WC did not alter blood parameter concentrations and did not influence insulin sensitivity. Mammary tissue F2-isoprostane concentrations were lowest in WC-VEH and highest in AL-DMBA groups. Tumor incidence and burden were similar among all groups. The data obtained from this study do not support our hypothesis. This may be due to low dose of DMBA used, strain and age of the rats, number of WC cycles, and the amount of trans–fatty acids in the diets. 相似文献