首页 | 本学科首页   官方微博 | 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   798篇
  免费   42篇
  国内免费   24篇
耳鼻咽喉   7篇
儿科学   24篇
妇产科学   12篇
基础医学   75篇
口腔科学   7篇
临床医学   93篇
内科学   146篇
皮肤病学   4篇
神经病学   54篇
特种医学   73篇
外科学   106篇
综合类   10篇
预防医学   106篇
眼科学   59篇
药学   62篇
肿瘤学   26篇
  2021年   12篇
  2020年   6篇
  2019年   6篇
  2018年   9篇
  2017年   10篇
  2016年   14篇
  2015年   12篇
  2014年   11篇
  2013年   23篇
  2012年   22篇
  2011年   23篇
  2010年   19篇
  2009年   13篇
  2008年   25篇
  2007年   45篇
  2006年   26篇
  2005年   29篇
  2004年   22篇
  2003年   17篇
  2002年   26篇
  2001年   25篇
  2000年   20篇
  1999年   29篇
  1998年   25篇
  1997年   20篇
  1996年   21篇
  1995年   21篇
  1994年   20篇
  1993年   26篇
  1992年   15篇
  1991年   27篇
  1990年   24篇
  1989年   31篇
  1988年   23篇
  1987年   17篇
  1986年   23篇
  1985年   17篇
  1984年   11篇
  1983年   12篇
  1982年   8篇
  1981年   4篇
  1980年   4篇
  1979年   10篇
  1978年   13篇
  1977年   4篇
  1976年   5篇
  1975年   8篇
  1972年   6篇
  1971年   4篇
  1966年   3篇
排序方式: 共有864条查询结果,搜索用时 15 毫秒
1.
A convenience sample of hospital workers, those receiving influenza vaccine and those not receiving vaccine, were asked to complete questionnaires delineating the occurrence of symptoms (e.g., fever, headache, extreme tiredness, dry cough, sore throat, runny nose, stuffy nose, muscle aches) and absenteeism in the 7-day period post-vaccination if vaccinated. Those unvaccinated completed the questionnaire in a self-selected 7 consecutive day period during the study conducted from November 2004 to February 2005. Those receiving either Fluzone or FluMist reported significantly fewer symptoms and related absenteeism than the unvaccinated group (p < .05). Administration of influenza vaccine did not result in higher rates of post-vaccination symptoms as compared to an unvaccinated group. Further, vaccinated employees did not experience higher absenteeism rates as a result of receiving either influenza vaccine. However, for those reporting absenteeism as a result of symptoms, mean absenteeism days were highest in the FluMist group (4.5 days) compared to the unvaccinated group (2.1 days) and the Fluzone group (1.9 days).  相似文献   
2.
3.
4.
A greenstick intercondylar fracture of the distal humerus occurred in a 14-year-old boy. The minimal displacement and stability of the injury allowed early range of motion with healing in an anatomic position and restoration of the preinjury arc of motion.  相似文献   
5.
The beta-amyloid (Abeta) precursor protein (APP) is cleaved sequentially by beta-site of APP-cleaving enzyme (BACE) and gamma-secretase to release the Abeta peptides that accumulate in plaques in Alzheimer's disease (AD). GGA1, a member of the Golgi-localized gamma-ear-containing ARF-binding (GGA) protein family, interacts with BACE and influences its subcellular distribution. We now report that overexpression of GGA1 in cells increased the APP C-terminal fragment resulting from beta-cleavage but surprisingly reduced Abeta. GGA1 confined APP to the Golgi, in which fluorescence resonance energy transfer analyses suggest that the proteins come into close proximity. GGA1 blunted only APP but not notch intracellular domain release. These results suggest that GGA1 prevented APP beta-cleavage products from becoming substrates for gamma-secretase. Direct binding of GGA1 to BACE was not required for these effects, but the integrity of the GAT (GGA1 and TOM) domain of GGA1 was. GGA1 may act as a specific spatial switch influencing APP trafficking and processing, so that APP-GGA1 interactions may have pathophysiological relevance in AD.  相似文献   
6.
The synthesis of boron-containing 1,3,5-triazines and 1,2,4-triazines is described. Derivatives of 1,3,5-triazine containing the o-carborane cluster have been obtained by reacting the corresponding propargyl derivatives with B(10)H(14). Derivatives of 1,2,4-triazine containing the B(12)H(12)(2-) cluster have been obtained by nucleophilic substitution of ethylsulfone derivatives with B(12)H(11)SH(2-). They have been isolated in their ring-protonated form. Reaction of RNH(2)-B(8)H(11)NH-R with stericly demanding heterocycles failed, either for steric or for solubility reasons.  相似文献   
7.
Research concerning hypothesized relationships between parental alcoholism and conduct problems in their children has had mixed findings. In this study, general and specific aspects of a possible relationship between a history of parental substance abuse (a category including parental alcohol abuse and parental abuse of other substances) with antisocial behavior and severe aggressive/destructive behavior was studied by reviewing preadmission variables in a large group of hospital-treated children and adolescents. The results indicated that various categories of more specifically defined parental substance abuse (e.g., substance abuse in fathers) were related to severe aggressive/destructive behavior and/or conduct disorder in their children. Parental abuse of nonalcohol substances appears to be more important than parental alcohol abuse in predicting severe aggressive and antisocial behavior. Substance abuse in fathers, especially abuse of substances other than alcohol, also seems more important than substance abuse in mothers in predicting severe aggression and conduct disorder.  相似文献   
8.
Mental health organizations are in the midst of massive changes brought about by managed care. This paper explores attitudes and reactions of leaders in mental health organizations to these changes. The leader's own conflicts regarding this approach to mental health care is a major determinant of why some organizations adapt more readily than others. Strategies for leaders that recognize the need to address conflict within the individual and the organization are discussed. The importance of facilitating dynamic interactional processes between leaders and non-leaders in regard to mutual expectations also is emphasized.  相似文献   
9.
Gaze control in various conditions is important, since retinal slip deteriorates the perception of 3-D shape of visual stimuli. Several studies have shown that visual perception of 3-D shape is better for actively moving observers than for passive observers watching a moving object. However, it is not clear to what extent the improved percept of 3-D shape for active observers has to be attributed to corollary discharges to higher visual centers or whether the improved percept might be due to improved gaze stabilization during active head movements. The aim of this study was to measure binocular eye movements and to make a quantitative comparison of retinal slip for subjects instructed to fixate a visual stimulus in an active condition (subject makes an active head movement, object is stationary) and in a passive condition (the stimulus moves, the subject is stationary) for various movement frequencies, viewing distances, and stimulus diameters. Retinal slip remains below the acuity threshold of about 4 deg/s in active conditions, except for the highest frequency tested in this study (1.5 Hz) for nearby targets (0.25 cm). Retinal slip exceeds this threshold for most passive conditions. These results suggest that the enhanced performance in the visual perception of 3-D shape during active head movements can, at least partly, be explained by better fixation by actively moving observers.  相似文献   
10.
Analysis of the mechanism of lipoprotein(a) assembly   总被引:2,自引:0,他引:2  
We have assessed the ability of a battery of purified recombinant apolipoprotein(a) (r-apo(a)) derivatives to bind to immobilized low-density lipoprotein (LDL) by ELISA. Removal of the apo(a) kringle IV type 8 and type 9 sequences dramatically reduced apo(a) binding to LDL. The binding of apo(a) to LDL was effectively inhibited by arginine, lysine, the lysine analogue ε-aminocaproic acid and proline; comparable inhibition was observed using the 17K and KIV5–8 r-apo(a) derivatives, suggesting a direct role for sequences contained in the latter species in mediating the initial non-covalent interactions which precede specific disulfide bond formation. We also determined that r-apo(a) binds directly to a synthetic apoB peptide spanning amino acid residues 3732–3745; this interaction appeared to be mediated by sequences present in apo(a) kringle IV types 8 and 9, and could be inhibited by arginine, lysine and proline. The results of this study indicate that the efficiency of Lp(a) assembly is a direct function of the initial non-covalent interactions between apo(a) and LDL; in addition, these studies suggest that Cys3734 in apoB mediates covalent linkage with apo(a) by virtue of the ability of the apoB sequences surrounding this residue to directly interact with apo(a) KIV type 9.  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