全文获取类型
收费全文 | 208382篇 |
免费 | 5107篇 |
国内免费 | 507篇 |
学科分类
医药卫生 | 213996篇 |
出版年
2021年 | 641篇 |
2018年 | 3998篇 |
2017年 | 4219篇 |
2016年 | 3532篇 |
2015年 | 5291篇 |
2014年 | 4872篇 |
2013年 | 4082篇 |
2012年 | 10940篇 |
2011年 | 5809篇 |
2010年 | 2783篇 |
2009年 | 4395篇 |
2008年 | 2921篇 |
2007年 | 3646篇 |
2006年 | 3846篇 |
2005年 | 11969篇 |
2004年 | 13328篇 |
2003年 | 8855篇 |
2002年 | 4015篇 |
2001年 | 4457篇 |
2000年 | 1778篇 |
1999年 | 5938篇 |
1998年 | 650篇 |
1992年 | 6953篇 |
1991年 | 7160篇 |
1990年 | 7405篇 |
1989年 | 7005篇 |
1988年 | 6516篇 |
1987年 | 6291篇 |
1986年 | 5995篇 |
1985年 | 5293篇 |
1984年 | 3641篇 |
1983年 | 2955篇 |
1982年 | 1040篇 |
1981年 | 815篇 |
1980年 | 873篇 |
1979年 | 3855篇 |
1978年 | 2401篇 |
1977年 | 1820篇 |
1976年 | 1595篇 |
1975年 | 2506篇 |
1974年 | 3136篇 |
1973年 | 2762篇 |
1972年 | 2781篇 |
1971年 | 2759篇 |
1970年 | 2574篇 |
1969年 | 2481篇 |
1968年 | 2255篇 |
1967年 | 2175篇 |
1966年 | 1912篇 |
1965年 | 1137篇 |
排序方式: 共有10000条查询结果,搜索用时 29 毫秒
1.
2.
3.
4.
5.
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
6.
7.
Peer-led teaching is an established paradigm with benefits for student teachers, learners and the wider medical community. Students are increasingly taking ownership of such teaching, which has fuelled the creation of new peer-led medical education societies at universities around the UK. Students wishing to undertake such an endeavor must contend with concerns over the quality of peer-led teaching, logistical challenges, lack of senior support and difficulties accessing relevant resources to design and appraise their initiatives. Peer-led medical education societies represent a relatively novel concept, and students may struggle to find practical information on how to approach these challenges. We propose that these obstacles can be overcome by thorough event planning, understanding the role and features of high quality peer-led education in supplementing medical school curricula, maintaining a strong working relationship with local medical faculty, and learning from the wider medical education community. 相似文献
8.
9.
Attachment is a behavioral and physiological system, which enables individual’s dynamic adaptation to its environment. Attachment develops in close interaction between an infant and his/her mother, plays an important role in the development of the infant’s brain, and influences the quality of interpersonal relationships throughout life.Security of attachment is believed to influence individual response to stress, exposing insecurely organized individuals to deregulated autonomic nervous system and exaggerated hypothalamic-pituitary-adrenal activity, which, in turn, produces increased and prolonged exposure to stress-hormones. Such stress responses may have considerable implications for the development of diverse health-risk conditions, such as insulin resistance and hyperlipidemia, shown by numerous studies.Although the mechanisms are not yet fully understood, there is compelling evidence highlighting the role of psychological stress in the development of type 1 diabetes (T1D). One of the possible contributing factors for the development of T1D may be the influence of attachment security on individual stress reactivity. Thus, the suggestion is that insecurely attached individuals are more prone to experience increased and prolonged influence of stress hormones and other mechanisms causing pancreatic beta-cell destruction.The present paper opens with a short overview of the field of attachment in children, the principal attachment classifications and their historic development, describes the influence of attachment security on individual stress-reactivity and the role of the latter in the development of T1D. Following is a review of recent literature on the attachment in patients with T1D with a conclusion of a proposed role of attachment organization in the etiology of T1D. 相似文献
10.
Torbj?rn Karlsson 《Upsala journal of medical sciences》2015,120(4):257-262
Background. Haemophagocytic lymphohistiocytosis (HLH) is a rare clinical syndrome characterized by fever, hepatosplenomegaly, cytopenia, and progressive multiple-organ failure. HLH in adults is often secondary to autoimmune diseases, cancer, or infections in contrast to familial HLH. Treatment of secondary HLH is directed against the triggering disease in addition to immunosuppressive therapy, the latter commonly according to the HLH-2004 protocol.Methods. We conducted a retrospective study to identify triggering diseases, disease-specific and immunosuppressive therapy administered, and prognosis in adult patients with secondary HLH. Patient data were collected from October 2010 to January 2015.Results. Ten adult patients with secondary HLH were identified. Seven were men, and the median age at diagnosis was 62 years. Five cases were triggered by malignant disease and five by infection. The median patient fulfilled five of the eight HLH-2004 diagnostic criteria. All patients fulfilled the criteria fever, cytopenia, and ferritin >500 µg/L. Median time from hospital admission to HLH diagnosis was 20 days. Four patients received immunosuppressive therapy according to the HLH-2004 protocol. The prognosis was dismal, especially for the patients with malignancy-associated HLH, of whom all died.Conclusion. HLH should be suspected in patients who present with fever, cytopenia, and ferritin >500 µg/L. Secondary HLH has a dismal prognosis. None of the patients with HLH triggered by malignancy survived. Achieving remission of the triggering disease seems to be important for a favourable outcome as, in all surviving patients, the haemophagocytic syndrome resolved after remission of the underlying infection. 相似文献