全文获取类型
收费全文 | 39530篇 |
免费 | 2639篇 |
国内免费 | 185篇 |
专业分类
耳鼻咽喉 | 517篇 |
儿科学 | 876篇 |
妇产科学 | 798篇 |
基础医学 | 5383篇 |
口腔科学 | 2532篇 |
临床医学 | 3293篇 |
内科学 | 8074篇 |
皮肤病学 | 798篇 |
神经病学 | 3345篇 |
特种医学 | 1244篇 |
外科学 | 5159篇 |
综合类 | 277篇 |
现状与发展 | 1篇 |
一般理论 | 34篇 |
预防医学 | 3933篇 |
眼科学 | 881篇 |
药学 | 2924篇 |
中国医学 | 256篇 |
肿瘤学 | 2029篇 |
出版年
2024年 | 39篇 |
2023年 | 394篇 |
2022年 | 800篇 |
2021年 | 1540篇 |
2020年 | 906篇 |
2019年 | 1244篇 |
2018年 | 1529篇 |
2017年 | 1080篇 |
2016年 | 1164篇 |
2015年 | 1369篇 |
2014年 | 1807篇 |
2013年 | 2177篇 |
2012年 | 3168篇 |
2011年 | 3383篇 |
2010年 | 1813篇 |
2009年 | 1522篇 |
2008年 | 2406篇 |
2007年 | 2421篇 |
2006年 | 2121篇 |
2005年 | 1997篇 |
2004年 | 1709篇 |
2003年 | 1514篇 |
2002年 | 1307篇 |
2001年 | 610篇 |
2000年 | 505篇 |
1999年 | 494篇 |
1998年 | 278篇 |
1997年 | 206篇 |
1996年 | 176篇 |
1995年 | 140篇 |
1994年 | 128篇 |
1993年 | 96篇 |
1992年 | 237篇 |
1991年 | 201篇 |
1990年 | 171篇 |
1989年 | 174篇 |
1988年 | 146篇 |
1987年 | 105篇 |
1986年 | 125篇 |
1985年 | 95篇 |
1984年 | 109篇 |
1983年 | 90篇 |
1982年 | 58篇 |
1981年 | 65篇 |
1980年 | 64篇 |
1979年 | 68篇 |
1978年 | 49篇 |
1977年 | 40篇 |
1976年 | 51篇 |
1974年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
2.
3.
Selwyn Arlington Headley Nayara Emily Viana Mariana de Mello Zanim Michelazzo Ana Aparecida Correa Xavier Cícero Júlio Silva Costa Felipe Hideki Ogo de Pinho Marcelo Diniz dos Santos 《Transboundary and Emerging Diseases》2020,67(Z2):49-59
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2. 相似文献
4.
5.
6.
7.
Moises Rodriguez-Gonzalez Antonio Moruno Tirado Reza Hosseinpour Jose Santos de Soto 《Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital》2015,42(4):350-356
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic. 相似文献
8.
9.
10.