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   5574篇
  免费   449篇
  国内免费   5篇
  6028篇
  2023年   38篇
  2022年   61篇
  2021年   95篇
  2020年   88篇
  2019年   78篇
  2018年   86篇
  2017年   86篇
  2016年   142篇
  2015年   251篇
  2014年   295篇
  2013年   371篇
  2012年   403篇
  2011年   347篇
  2010年   235篇
  2009年   215篇
  2008年   319篇
  2007年   321篇
  2006年   275篇
  2005年   253篇
  2004年   281篇
  2003年   255篇
  2002年   205篇
  2001年   90篇
  2000年   74篇
  1999年   83篇
  1998年   60篇
  1997年   43篇
  1996年   55篇
  1995年   57篇
  1994年   45篇
  1993年   45篇
  1992年   57篇
  1991年   63篇
  1990年   59篇
  1989年   54篇
  1988年   35篇
  1987年   44篇
  1986年   39篇
  1985年   46篇
  1984年   44篇
  1983年   31篇
  1982年   24篇
  1981年   22篇
  1980年   25篇
  1979年   19篇
  1978年   19篇
  1975年   18篇
  1974年   20篇
  1973年   20篇
  1972年   17篇
排序方式: 共有6028条查询结果,搜索用时 0 毫秒
111.
Anita Herle 《Ethnos》2013,78(2):253-274
Preparations for a centenary exhibition to mark the 1898 Cambridge Anthropological Expedition to the Torres Strait incorporated cross-cultural collaborative work, reflecting the changing roles of museums as sites for contact and research combining curatorial expertise and indigenous knowledge. Specific objects in the collections of the University of Cambridge Museum of Archaeology and Anthropology continue to be active intermediaries in the relationship between museum staff and Torres Strait Islanders and the museum itself has become an important field site. This paper provides an ethnography of the process of creating the exhibition and explores different ways that many of the objects displayed have resonance for Islanders today.  相似文献   
112.
Summary 1242 HLA-ABC haplotypes of the North German population (Hamburg) as deduced by family analyses are described. They are in perfect agreement with recently published data by Mayr (1977) from Austria (Vienna) in all parameters tested: frequency of the single HLA-alleles, haplotype distribution and linkage disequilibrium values. Gametic association studies revealed that 69.4% of the B and C genes (map distance 0.2 cM) 36.9% of the A and C genes (0.6 cM), but only 23.2% of the A and B genes (0.8 cM) were significantly more often combined than expected due to their frequencies. From these findings it seems likely that the linkage disequilibrium within the MHC is rather due to a short evolutionary period than to selective forces. Some observations as to the most common European haplotype A1,B8 are discussed.  相似文献   
113.
1. Lipogenesis has been studied in intact genetically obese mice by measuring the incorporation of a single oral dose of 250mg. of [U-14C]glucose into fatty acid and cholesterol in the liver and extrahepatic tissues. Studies were also carried out with [U-14C]glucose added to the diet and fed for 24hr. With either method of isotope administration, the conversion of [U-14C]glucose into fatty acid was greatly elevated in the livers of the obese mice. In contrast, conversion of the single dose of [14C]glucose into fatty acid in extrahepatic tissues of obese mice was only half that occurring in the non-obese litter mates. When [14C]glucose was given in the diet for 24hr. the total accumulation of labelled fatty acid in extrahepatic tissues of obese mice was slightly less than in the non-obese. Uptake of labelled glucose and conversion into fatty acid in adipose tissue of the obese mice decreased with age. 2. Conversion of the single dose of [14C]glucose into liver cholesterol was comparable in obese and non-obese mice fed on a purified low-fat diet. However, obese mice given this diet for 12 weeks accumulated 1·54% of cholesterol in the liver compared with 0·29% in the non-obese litter mates. This accumulation apparently resulted from a decrease in removal of cholesterol from the liver, rather than an increased synthesis. 3. Conversion of the single dose of [14C]glucose into extrahepatic fatty acid was decreased by 18hr. starvation proportionally as much in obese as in non-obese mice. The decrease in liver fatty acid synthesis caused by starvation also was considerable in obese mice, although somewhat less marked than in the non-obese. 4. The metabolic derangements in the liver could be more fundamental to the development of the obesity than the changes seen in extrahepatic tissues.  相似文献   
114.
We have previously produced a series of antigalactose (anti-Gal) hybridomas and characterized their heavy chain gene usage. Here we have quantified the affinity of these Abs for the alpha-Gal epitope and characterized their in vitro effects on endothelial cell activation and apoptosis. We report that anti-Gal mAbs derived from Gal(-/-) mice show a range of affinity for the alpha-Gal epitope, and that affinity was generally increased as the V(H) gene usage transitioned from germline sequences to sequences exhibiting somatic maturation. Despite an 85-fold range in affinity, all the anti-Gal mAbs examined induced alpha-Gal-specific endothelial cell activation, and after prolonged exposure induced endothelial cell apoptosis in a complement-independent manner. Only murine anti-Gal mAbs of the IgM or IgG3 subclass, but not IgG1, were effective at initiating complement-dependent cell lysis. Using a novel rat to mouse xenograft model, we examined the in vivo ability of these mAbs to induce xenograft rejection and characterized the rejection using histology and immunohistochemistry. Infusion of complement-fixing IgG3 mAbs resulted in either hyperacute rejection or acute vascular rejection of the xenograft. Surprisingly, infusion of an equal amount of a high affinity anti-Gal IgG1 mAb, that fixed complement poorly also induced a rapid xenograft rejection, which we have labeled very acute rejection. These studies emphasize the importance of in vivo assays, in addition to in vitro assays, in understanding the role of anti-Gal IgG-mediated tissue injury and xenograft rejection.  相似文献   
115.

Objectives

How medical students handle negative emotions expressed by simulated patients during Objective Structured Clinical Examinations (OSCE) has not been fully investigated. We aim to explore (i) whether medical students respond differently to different types of patients’ emotional cues; and (2) possible effects of patients’ progressive disclosure of emotional cues on students’ responses.

Methods

Forty OSCE consultations were video recorded and coded for patients’ expressions of emotional distress and students’ responses using a validated behavioural coding scheme (the Verona Coding Definitions of Emotional Sequence). Logistic multilevel regression was adopted to model the probability of the occurrence of student reduce space response behaviour as a function of the number of patients’ expressions of emotional cues.

Results

We found that medical students offered responses that differed to emotional cue types expressed by simulated patients. Students appeared to provide space to emotional cues when expressed in vague and unspecific words and reduce space to cues emphasizing physiological or cognitive correlates. We also found that medical students were less likely to explore patients’ emotional distress nearer the end of the consultation and when the duration of a patient speech turn got larger. Cumulative frequency of patients’ emotional cues also predicted students’ reduce space behaviour.

Practical Implications

Understanding how medical students manage negative emotions has significant implications for training programme development focusing on emotion recognition skills and patient-centred communication approach. In addition, the statistical approaches adopted by this study will encourage researchers in healthcare communication to search for appropriate analytical techniques to test theoretical propositions.  相似文献   
116.
117.
118.
119.
Podocytes are insulin-sensitive and take up glucose in response to insulin. This requires nephrin, which interacts with vesicle-associated membrane protein 2 (VAMP2) on GLUT4 storage vesicles (GSVs) and facilitates their fusion with the plasma membrane. In this paper, we show that the filament-forming GTPase septin 7 is expressed in podocytes and associates with CD2-associated protein (CD2AP) and nephrin, both essential for glomerular ultrafiltration. In addition, septin 7 coimmunoprecipitates with VAMP2. Subcellular fractionation of cultured podocytes revealed that septin 7 is found in both cytoplasmic and membrane fractions, and immunofluorescence microscopy showed that septin 7 is expressed in a filamentous pattern and is also found on vesicles and the plasma membrane. The filamentous localization of septin 7 depends on CD2AP and intact actin organization. A 2-deoxy-d-glucose uptake assay indicates that depletion of septin 7 by small interfering RNA or alteration of septin assembly by forchlorfenuron facilitates glucose uptake into cells and further, knockdown of septin 7 increased the interaction of VAMP2 with nephrin and syntaxin 4. The data indicate that septin 7 hinders GSV trafficking and further, the interaction of septin 7 with nephrin in glomeruli suggests that septin 7 may participate in the regulation of glucose transport in podocytes.  相似文献   
120.
The objective of this study was to describe the rate of change in knee cartilage volume over 4.5 years in subjects with symptomatic knee osteoarthritis (OA) and to determine factors associated with cartilage loss. One hundred and five subjects were eligible for this longitudinal study. Subjects' tibial cartilage volume was assessed by magnetic resonance imaging (MRI) at baseline, at 2 years and at 4.5 years. Of 105 subjects, 78 (74%) completed the study. The annual percentage losses of medial and lateral tibial cartilage over 4.5 years were 3.7 ± 4.7% (mean ± SD; 95% confidence interval 2.7 to 4.8%) and 4.4 ± 4.7% (mean ± SD; 95% confidence interval 3.4 to 5.5%), respectively. Cartilage volume in each individual seemed to track over the study period, relative to other study participants. After multivariate adjustment, annual medial tibial cartilage loss was predicted by lesser severity of baseline knee pain but was independent of age, body mass index and structural factors. No factors specified a priori were associated with lateral cartilage volume rates of change. Tibial cartilage declines at an average rate of 4% per year in subjects with symptomatic knee OA. There was evidence to support the concept that tracking occurs in OA. This may enable the prediction of cartilage change in an individual. The only significant factor affecting the loss of medial tibial cartilage was baseline knee pain, possibly through altered joint loading.  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