全文获取类型
收费全文 | 49121篇 |
免费 | 5674篇 |
国内免费 | 345篇 |
学科分类
医药卫生 | 55140篇 |
出版年
2024年 | 133篇 |
2023年 | 794篇 |
2022年 | 585篇 |
2021年 | 1224篇 |
2020年 | 1335篇 |
2019年 | 1183篇 |
2018年 | 1811篇 |
2017年 | 1521篇 |
2016年 | 1761篇 |
2015年 | 1689篇 |
2014年 | 2396篇 |
2013年 | 2925篇 |
2012年 | 3364篇 |
2011年 | 3357篇 |
2010年 | 2308篇 |
2009年 | 2366篇 |
2008年 | 2937篇 |
2007年 | 2890篇 |
2006年 | 2714篇 |
2005年 | 2680篇 |
2004年 | 2368篇 |
2003年 | 2230篇 |
2002年 | 2091篇 |
2001年 | 572篇 |
2000年 | 401篇 |
1999年 | 575篇 |
1998年 | 685篇 |
1997年 | 627篇 |
1996年 | 582篇 |
1995年 | 563篇 |
1994年 | 395篇 |
1993年 | 333篇 |
1992年 | 317篇 |
1991年 | 315篇 |
1990年 | 207篇 |
1989年 | 302篇 |
1988年 | 233篇 |
1987年 | 203篇 |
1986年 | 199篇 |
1985年 | 200篇 |
1984年 | 204篇 |
1983年 | 159篇 |
1982年 | 151篇 |
1981年 | 130篇 |
1980年 | 138篇 |
1979年 | 87篇 |
1978年 | 94篇 |
1977年 | 91篇 |
1976年 | 75篇 |
1975年 | 85篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Christine Roberts Deborah Turnbull Les Irwig 《Australian and New Zealand journal of public health》1992,16(1):58-65
Abstract: The aim of this study was to determine changes in Sydney general practitioners' (GPs) knowledge about, attitude towards and intention to recommend screening mammography over the two years since a screening mammography program was first implemented in the Central Sydney Health Service (CSHS) area. 123 GPs from the CSHS area were selected from a list maintained by the Breast X-ray Programme, while 127 GPs from the rest of Sydney were selected from the Yellow Pages telephone directory. The overall response rate was 84 per cent. Outcomes were assessed by a self-administered questionnaire covering knowledge, attitudes and beliefs, self-report of recent referral practice, intention to recommend, and sources of information about mammography screening. Demographic data were also collected. Results showed that overall knowledge has increased both inside and outside the CSHS area, but important deficiencies in knowledge remain in both areas. Attitudes to screening mammography have improved in the CSHS area, especially regarding the efficacy of screening mammography and patient compliance. Importantly, positive views of screening mammography have declined outside the CSHS area, especially about whether screening mammography can save women's lives. GPs in both areas remain concerned about costs. The presence and strategies of the Breast X-ray Programme have had some positive effect on the attitudes of GPs towards, but not knowledge of, screening mammography. 相似文献
102.
Margaret J. Tango Evelyn Safaris Margarita Romanella Atousa Aminian Marina Katerelos Christine Somerwille RIek G. Tearle Martin J. Pearse Anthony J.E d'Apice 《Xenotransplantation》1997,4(1):25-33
Abstract: Transgenic expression of the human complement regulatory molecule CD59 in mice and genetic deletion of the major xenoantigen galactose α 1,3 galactose (Gal KO) each resulted in partial protection of spleen cells from lysis by human serum. These protective effects were additive when the two genetic modifications were combined. However, when the effects of these genetic modifications were examined in an ex vivo model in which mouse hearts were perfused with human plasma, it was Gal KO which was the modification which determined protection. CD59 expression alone was not protective and CD59 expression in combination with Gal knockout did not result in a significant additional increase in protection over and above that provided by Gal knockout alone. The likely explanation for this discrepancy between the in vitro and ex vivo data is that the H2-Kb promoter used to drive CD59 expression results I in substantially less expression on endothelium than on spleen cells. 相似文献
103.
104.
The current study evaluated psychosocial variables that may contribute to the experience of headache in college adults. One hundred ninety-nine participants, 103 women and 96 men, completed head pain logs for 4 weeks after completing measures assessing psychosocial variables. Multiple regression analyses indicated that level of emotional functioning, perception of stress, and gender were predictive of future headache frequency, intensity, and duration. Family history and health habits did not predict headache activity. These findings are consistent with research investigating psychosocial variables and headache activity. 相似文献
105.
J J Tiedeman L Lippiello J F Connolly B S Strates 《Clinical orthopaedics and related research》1990,(253):279-286
A noninvasive method was developed to assess fracture healing using optical densitometric methodology. Photometric measurements of osseous tissue density were based on illuminance or intensity of light, transmitted through standard roentgenograms. The method was tested in 6-mm tibial segmental defects and single-cut osteotomy defects in adult mongrel dogs. The lowest measureable bone density in the defect was compared to bending rigidity of the involved extremity. For both types of defect, an exponential relationship was found between the densitometric evaluation of the healing fracture gap and bending rigidity. This method proved superior to a roentgenographic scoring method and is capable of detecting small differences in mineral content using standard roentgenograms. The high correlation between densitometric evaluation and bone rigidity indicates this method has potential for use in the in vivo assessment of fracture healing. 相似文献
106.
107.
A comparison of the stressors experienced by parents of intubated and non-intubated children 总被引:3,自引:0,他引:3
Caroline Haines BN RGN RSCN Christine Perger BHSc Sue Nagy RN BA FRCNA FCN 《Journal of advanced nursing》1995,21(2):350-355
When children are ill enough to require admission to paediatric intensive care, parents may become distressed about their child's medical condition and this distress may be compounded by the unfamiliar nature of the highly technological environment Parents of children who are sick enough to warrant intubation are particularly likely to be exposed to a frightening array of technological equipment Seventy-one parents of intubated and non-intubated children completed the Parental Stressor Scale Paediatnc Intensive Care Unit (PSS PICU) Overall the findings suggest that parents were most distressed (a) by the painful procedures to which their children were subjected, (b) by the sights and sounds of the intensive care unit and (c) by their children's reactions to intensive care The behaviour of staff towards parents and the way that staff communicated with them caused the least distress When the levels of stress reported by parents of intubated children were compared with those reported by parents of non-intubated children, different patterns of stress were found Painful procedures were a source of greater stress to parents of intubated children whereas the behaviour of staff and the children's reactions to the intensive care experience caused greater stress to the parents of the non-intubated children In general the findings suggest that the needs of parents of non-intubated children are being overlooked, with staff focusing more of their attention on the parents of intubated children 相似文献
108.
A J Waring C M Housworth R M Voorhies J R Douglas C F Walker S E Connolly 《Surgical neurology》1990,34(3):139-143
The authors have developed and patented a neurosurgical retractor system incorporating an infrared emitter and detector that allows detection of cerebral pulsations. Gentle contact with the surface of cat brains shows cerebral pulsations that correlate with arterial pulse as well as mechanical ventilation. The amplitude of cerebral pulsations decreases with higher retraction pressure and disappears at approximately 20 mmHg. The pressure on the surface of the brain decreased 50% in 5 minutes even though the position of the retractor was maintained constant. The authors postulate that monitoring cerebral pulsation may prove useful in clinical neurosurgery with respect to avoiding excessive retraction, which causes brain damage. 相似文献
109.
Helmut Seidel Barbara Harazin Kristina Pavlas Christine Sroka Jörg Richter Ralph Blüthner Udo Erdmann Jan Grzesik Barbara Hinz Reinhard Rothe 《International archives of occupational and environmental health》1988,61(1-2):95-106
Summary This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at 92 dBA, whole-body vibration (V) in the Z-axis at 4 Hz and 1.0 ms–2 rms, and noise and vibration (NV) for 90 min with each condition. Temporary threshold shifts of hearing (TTS) and their integrals (ITTS) were measured at 4, 6, 10, and 12 kHz. Visual acuity was examined by means of a very sensitive test. Cross-modality matching (CMM) of the handgrip force was used to judge the subjectively experienced strain. NV induced a clear tendency of higher TTS and ITTS than N, with several significant differences most pronounced at 10 kHz. With repeated exposures, the effect of NV decreased, while the reactions to N and V remained unchanged. The individual reactions to NV differed. The influence of the duration of exposures on vision depended on the condition; N caused time-dependent changes, whereas V did not. CMM-data increased with the duration of the exposure during V and NV. N was generally judged to be more straining than V; NV caused higher strain than V during the first 30 min of exposure only. Correlations between different effects suggest certain links between them. Additionally, less motivation — daily obtained by a questionnaire — often correlated with higher ITTS during N and NV. The results also illustrate the combined effects on the individual susceptibility, repetition of exposure, the kind of response, and, possibly, the actual psychic state.Abbreviations CMM
cross-modality matching
- MVC
maximum voluntary contraction force
- N
exposure condition: noise level 92dBA, no whole-body vibration
- NV
exposure condition: combined exposure to noise with a level of 92 dBA and wholebody vibration with 4 Hz, 1 ms–2 rms
- V
exposure condition: whole-body vibration with 4 Hz, 1 ms–2 rms
- TTS
temporary threshold shift
- ITTS
integral of temporary threshold shift
- WBV
whole-body vibration in the common sense
This work was done in the Temporary International Research Team on Combined Effects of Noise and Vibration of the Council of Mutual Economic Assistance of the Socialist Countries. The authors gratefully acknowledge the help and assistance of L.-M. Brumm, Y. Bening, M. Godau, G. Weber, and R. Vizcaino. 相似文献
110.
John D. Hughes MD Changyi Chen MD Samer G. Mattar MB ChB Ayten Someren MD Beverly Noe BS Carolyn R. Suwyn BS Alan B. Lumsden MD 《Annals of vascular surgery》1996,10(2):123-130
Hypothermia and preservative perfusates have been used to decrease ischemic renal injury. This study was performed to identify the preservative function of perfusates independent of the effects of hypothermia. Rats underwent 45 minutes of renal ischemia. Rectal and renal parenchyma temperatures were monitored and maintained within 1° C of normal. Perfusates were University of Wisconsin solution (UW), Euro-Collins solution, normal saline solution, and Ringer's lactate solution. A nonperfused ischemic control and a nonischemic control group were also evaluated. Parameters evaluated included serum creatinine and blood urea nitrogen levels, renal ischemic injury grade, renal weight, and gross appearance of the injured kidney. Rats treated with UW solution were found to have a significantly lower creatinine, blood urea nitrogen, and injury grade than the other three perfused groups. The external gross appearance of the UW-treated kidneys was normal, whereas that of the other groups demonstrated moderate to severe injury. Although the mean right/left renal weight difference of the UW-treated group was lower than that of the other three groups, this was not statistically significant. Under normothermic conditions in rats, UW solution affords significant renal protection from ischemia. Euro-Collins, normal saline, and Ringer's lactate solutions display no significant protective effect.Presented at the Twentieth Annual Meeting of the Peripheral Vascular Surgery Society, New Orleans, La., June 10, 1995. 相似文献