首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   192269篇
  免费   2039篇
  国内免费   138篇
医药卫生   194446篇
  2024年   31篇
  2023年   255篇
  2022年   695篇
  2021年   1081篇
  2020年   727篇
  2019年   878篇
  2018年   22724篇
  2017年   17929篇
  2016年   20137篇
  2015年   1661篇
  2014年   1828篇
  2013年   1944篇
  2012年   8512篇
  2011年   22512篇
  2010年   19679篇
  2009年   12173篇
  2008年   20437篇
  2007年   22531篇
  2006年   1296篇
  2005年   2790篇
  2004年   3853篇
  2003年   4726篇
  2002年   2809篇
  2001年   310篇
  2000年   469篇
  1999年   214篇
  1998年   241篇
  1997年   240篇
  1996年   126篇
  1995年   130篇
  1994年   111篇
  1993年   88篇
  1992年   62篇
  1991年   106篇
  1990年   143篇
  1989年   97篇
  1988年   71篇
  1987年   51篇
  1986年   38篇
  1985年   46篇
  1984年   39篇
  1983年   37篇
  1982年   42篇
  1980年   51篇
  1974年   29篇
  1938年   60篇
  1937年   25篇
  1934年   30篇
  1932年   57篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Objective: To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.

Design/Methods: VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3?h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45?min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15?ml/kg of PRBC transfusion was given over 3?h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48?h after the transfusion.

Results: Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48?h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.

Conclusions: PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24?h post-transfusion.  相似文献   
2.
3.
4.
5.
6.
The formation of superoxide partially accounts for the well-known oxygen enhancement of radiation-induced biochemical changes and cell damage. Radioprotective effects of copper (II), manganese (IV) or vanadium (IV) complexes, of superoxide dismutase-mimetic activity, on body weight, survival rate and some biochemical parameters in pre-treated irradiated, untreated irradiated and treated non-irradiated female albino rats have been studied 24 h after whole body gamma-irradiation at a dose level of 6 Gy. Survival time, body weight, red blood cell (RBC) and white blood cell (WBC) counts, hemoglobin (Hb) concentration, percentage of hematocrit (Hct%), reduced glutathione (GSH), serum total protein, albumin, globulin (G), blood urea, creatinine and cholesterol were estimated, as well as the activities of blood superoxide dismutase (SOD), glutamate-oxaloacetic (GOT) and glutamate-pyruvic (GPT) transaminases, and alkaline phosphatase were assessed. A significant decline was shown in body weight, survival rate, the mean values of RBC and WBC counts, Hb and Hct percentages, and GSH concentration, as well as blood SOD activity, in whole body gamma-irradiated rats compared with the control non-irradiated rat group. The mean activity values of alkaline phosphatase, GOT and GPT, as well as the average values of blood urea, creatinine, total cholesterol, total protein and globulin were significantly elevated, while the average values of albumin and the albumin/globulin ratio were decreased in gamma-irradiated rats compared with the corresponding values of the normal control rat group. Pretreatment of rats with either manganese or vanadium complexes resulted in a significant increase in survival rate and body weight over that of the non-treated irradiated rat group. Pretreatment of rats with copper (II), manganese (IV) or vanadium (IV) complexes caused a significant increase in RBC and WBC counts, Hb concentration, HCt (%), GSH content and SOD activity in blood when compared to the irradiated rat group without treatment. The administration of copper (II), manganese (IV) or vanadium (IV) complexes prior to irradiation exposure resulted in a significant decrease in GOT and GPT activities in addition to blood urea, creatinine, cholesterol, globulin and total protein contents, while each complex exhibited a significant increase in plasma alkaline phosphatase, albumin, and the albumin/globulin ratio compared to the untreated irradiated rat group. Administration of vanadium (IV), manganese (IV) or copper (II) complexes in non-irradiated rats caused a significant increase in SOD activity without changing other biochemical parameters compared with the corresponding values of the normal control rat group. We conclude that these metallo-elements, particularly manganese (IV) and vanadium (IV) complexes of 2-methylaminopyridine, have radiation protection and radiation recovery. Furthermore, these metal complexes offer a new approach to overcome the pathological effects of ionizing radiation and suggest their use as a physiological approach to preventing or perhaps predominantly facilitating recovery from radiation injury.  相似文献   
7.
Anliegen dieses Artikels ist, die besondere Qualit?t und Chance von Psychodramatischer Supervision zu beschreiben, und gleichzeitig die Kompatibilit?t und fruchtbare Erg?nzung des Moreno’schen Ansatzes innerhalb des Formats Supervision innerhalb der Sozialen Arbeit auf zuzeigen. Dies wird anhand von 2 ausgew?hlten Praxisbeispielen dargestellt. Die Handlungskompetenz von Supervisandinnen und Supervisanden kann durch einfache psychodramatische Interventionen erweitert werden. Handlungshemmung wird überwunden, Spontaneit?t und Kreativit?t kommen ins Laufen und er?ffnen Perspektiven.  相似文献   
8.
9.
Relationship-centered care reflects both knowing and feeling: the knowledge that physician and patient bring from their respective domains of expertise, and the physician’s and patient’s experience, expression, and perception of emotions during the medical encounter. These processes are conveyed and reciprocated in the care process through verbal and nonverbal communication. We suggest that the emotional context of care is especially related to nonverbal communication and that emotion-related communication skills, including sending and receiving nonverbal messages and emotional self-awareness, are critical elements of high-quality care. Although nonverbal behavior has received far less study than other care processes, the current review argues that it holds significance for the therapeutic relationship and influences important outcomes including satisfaction, adherence, and clinical outcomes of care.  相似文献   
10.
Coronary flow reserve (CFR) has been used toassess coronary microcirculation and epicardial coro-nary stenoses[1— 3 ] . CFR is defined as the ratio ofcoronary flow under maximal coronary vasodilatationto coronary flow under resting conditions[4 ] .Whenthe cross- sectional area of epicardial coronary arteriesis constant,coronary flow velocity (CFV) ratios areequal to volume flow ratios.The most common method used clinically formeasuring CFVR is intracoronary Doppler flow(ICD) analysis re…  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号