全文获取类型
收费全文 | 78294篇 |
免费 | 5727篇 |
国内免费 | 408篇 |
专业分类
耳鼻咽喉 | 752篇 |
儿科学 | 1908篇 |
妇产科学 | 1859篇 |
基础医学 | 9710篇 |
口腔科学 | 1881篇 |
临床医学 | 7831篇 |
内科学 | 17306篇 |
皮肤病学 | 997篇 |
神经病学 | 6538篇 |
特种医学 | 2531篇 |
外国民族医学 | 2篇 |
外科学 | 12072篇 |
综合类 | 1191篇 |
现状与发展 | 2篇 |
一般理论 | 131篇 |
预防医学 | 6535篇 |
眼科学 | 2351篇 |
药学 | 5597篇 |
中国医学 | 159篇 |
肿瘤学 | 5076篇 |
出版年
2023年 | 393篇 |
2022年 | 612篇 |
2021年 | 1765篇 |
2020年 | 1021篇 |
2019年 | 1457篇 |
2018年 | 1764篇 |
2017年 | 1230篇 |
2016年 | 1360篇 |
2015年 | 1623篇 |
2014年 | 2431篇 |
2013年 | 3595篇 |
2012年 | 5048篇 |
2011年 | 5356篇 |
2010年 | 3023篇 |
2009年 | 2825篇 |
2008年 | 4991篇 |
2007年 | 5179篇 |
2006年 | 4952篇 |
2005年 | 5063篇 |
2004年 | 4646篇 |
2003年 | 4179篇 |
2002年 | 4081篇 |
2001年 | 850篇 |
2000年 | 695篇 |
1999年 | 825篇 |
1998年 | 869篇 |
1997年 | 709篇 |
1996年 | 579篇 |
1995年 | 565篇 |
1994年 | 521篇 |
1993年 | 492篇 |
1992年 | 586篇 |
1991年 | 551篇 |
1990年 | 461篇 |
1989年 | 482篇 |
1988年 | 431篇 |
1987年 | 406篇 |
1986年 | 379篇 |
1985年 | 439篇 |
1984年 | 466篇 |
1983年 | 423篇 |
1982年 | 554篇 |
1981年 | 477篇 |
1980年 | 517篇 |
1979年 | 312篇 |
1978年 | 338篇 |
1977年 | 335篇 |
1976年 | 277篇 |
1975年 | 299篇 |
1974年 | 258篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
Objective
The aim of the study was to estimate the effect of the state-based reinsurance programs through the section 1332 State Innovation Waivers on health insurance marketplace premiums and insurer participation.Data Source
2015 to 2022 Robert Wood Johnson Foundation Health Insurance Exchange Compare Datasets.Study Design
An event study difference-in-differences (DD) model separately for each year of implementation and a synthetic control method (SCM) are used to estimate year-by-year effects following program implementation.Data Collection/Extraction Methods
Not applicable.Principal Findings
Reinsurance programs were associated with a decline in premiums in the first year of implementation by 10%–13%, 5%–19%, and 11%–17% for bronze, silver, and gold plans (p < 0.05). There is a trend of sustained declines especially for states that implemented their programs in 2019 and 2020. The SCM analyses suggest some effect heterogeneity across states but also premium declines across most states. There is no evidence that reinsurance programs affected insurer participation.Conclusion
State-based reinsurance programs have the potential to improve the affordability of health insurance coverage. However, reinsurance programs do not appear to have had an effect on insurer participation, highlighting the need for policy makers to consider complementary strategies to encourage insurer participation. 相似文献2.
Rajendrababu Sharmila Puthuran George Varghese Alia Laxmi Ananya Uduman Mohammed Sithiq Wijesinghe Hiruni Kaushalya 《International ophthalmology》2022,42(8):2609-2618
International Ophthalmology - To investigate the efficacy and safety of non-valved Aurolab aqueous drainage implant (AADI) surgery combined with phacoemulsification in eyes with refractory glaucoma... 相似文献
3.
N. Cody Schaal Raushan A. Salaam Michael Stevens Alex Stubner 《Journal of occupational and environmental hygiene》2019,16(5):329-335
The purpose of this investigation was to characterize noise levels in spaces designated as “effective quiet” areas on a U.S. Navy aircraft carrier. Noise dosimetry samples were collected in 15 designated spaces, representing 15 noise measurements, while at-sea during airwing carrier qualifications. Equivalent sound level (Leq) measurements were collected during flight operations (Leq (flt ops)), non-flight operations (Leq (non-flt ops)), and over 24-hr periods (Leq (24-hr)). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH®) Threshold Limit Value (TLV®) for “effective quiet” areas intended for temporary threshold shift recovery when personnel live and work in a potentially noise hazardous environment for periods greater than 24?hr. The monitored areas were selected based on personnel occupancy/use during off-duty time periods. Areas were classified by either (1) leisure areas that included mess (eating areas), gyms, lounges, an internet cafe, and the fantail social area or (2) berthing (sleeping) areas. The Leq measurements in decibels “A” weighted (dBA) were compared to determine significant differences between Leq (flt ops), Leq (non-flt ops), and Leq (24-hr) and were compared between leisure area and berthing area. Measured noise levels according to time period ranged as follows: (1) Leq (24-hr): 70.8–105.4 dBA; (2) Leq (flt ops): 70–101.2 dBA; and (3) Leq (non-flt ops): 39.4–104.6 dBA. All area measurements over the 24-hr period and during flight operations and 46.7% of the areas during the non-flight operation time period exceeded the “effective quiet” 70 dBA ACGIH TLV. Mean Leqs were 15 dBA higher during flight operations compared to non-flight operations in “effective quiet” areas (p?=?0.001). The Leqs in leisure areas were significantly higher than berthing areas by approximately 21 dBA during non-flight operation periods (p?=?0.001). Results suggest noise levels in “effective quiet” areas frequented by aircraft carrier personnel during off-duty hours when at-sea may inhibit auditory recovery from occupational noise exposures that occur on-duty. 相似文献
4.
5.
6.
7.
8.
9.
10.