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   6506篇
  免费   585篇
  国内免费   1篇
  2023年   56篇
  2022年   148篇
  2021年   244篇
  2020年   134篇
  2019年   128篇
  2018年   150篇
  2017年   141篇
  2016年   229篇
  2015年   344篇
  2014年   392篇
  2013年   465篇
  2012年   581篇
  2011年   621篇
  2010年   327篇
  2009年   293篇
  2008年   354篇
  2007年   359篇
  2006年   339篇
  2005年   294篇
  2004年   248篇
  2003年   247篇
  2002年   254篇
  2001年   45篇
  2000年   38篇
  1999年   58篇
  1998年   50篇
  1997年   46篇
  1996年   38篇
  1995年   33篇
  1994年   26篇
  1993年   19篇
  1992年   27篇
  1991年   22篇
  1990年   13篇
  1989年   16篇
  1988年   22篇
  1987年   13篇
  1986年   15篇
  1985年   18篇
  1984年   15篇
  1983年   22篇
  1982年   10篇
  1981年   14篇
  1980年   18篇
  1979年   12篇
  1978年   15篇
  1977年   12篇
  1976年   11篇
  1974年   10篇
  1972年   12篇
排序方式: 共有7092条查询结果,搜索用时 15 毫秒
991.
This article explores the options that the Norwegian government has when it comes to the management of harvesting a new resource (redfeed) in the politically tense area surrounding Svalbard. The article argues that, by preparing a blueprint regime solely for redfeed rather than allowing the resource to be a catalyst for conflict, the impacts of introducing the fishery will be less dramatic.  相似文献   
992.
Synovial fibroblasts destroy articular cartilage and bone in rheumatoid arthritis, but the mechanism of fibroblast transformation remains elusive. Because gain-of-function mutations of BRAF can transform fibroblasts, we examined BRAF in rheumatoid synovial fibroblasts. The strong gain-of-function mutation, V600R, of BRAF found in melanomas and other cancers was identified in first passage synovial fibroblasts from two of nine rheumatoid arthritis patients and confirmed by restriction site mapping. BRAF-specific siRNA inhibited proliferation of synovial fibroblasts with V600R mutations. A BRAF aberrant splice variant with an intact kinase domain and partial loss of the N-terminal autoinhibitory domain was identified in fibroblasts from an additional patient, and fibroblast proliferation was inhibited by BRAF-specific siRNA. Our finding is the first to establish mechanisms for fibroblast transformation responsible for destruction of articular cartilage and bone in rheumatoid arthritis and establishes a new target for therapeutic intervention.  相似文献   
993.
Much of the recent neuropsychological literature on false beliefs (delusions) has tended to focus on individual or single beliefs, with few studies actually investigating the relationship or co-occurrence between different types of co-existing beliefs. Quine and Ullian proposed the hypothesis that our beliefs form an interconnected web in which the beliefs that make up that system must somehow “cohere” with one another and avoid cognitive dissonance. As such beliefs are unlikely to be encapsulated (i.e., exist in isolation from other beliefs). The aim of this preliminary study was to empirically evaluate the probability of belief co-occurrence as one indicator of coherence in a large sample of subjects involving three different thematic sets of beliefs (delusion-like, paranormal & religious, and societal/cultural). Results showed that the degree of belief co-endorsement between beliefs within thematic groupings was greater than random occurrence, lending support to Quine and Ullian’s coherentist account. Some associations, however, were relatively weak, providing for well-established examples of cognitive dissonance.  相似文献   
994.
We recently found that older adults show reduced learning rates when learning a new pattern of coordinated rhythmic movement. The purpose of this study was to extend that finding by examining the performance of all ages across the lifespan from the 20 s through to the 80 s to determine how learning rates change with age. We tested whether adults could learn to produce a novel coordinated rhythmic movement (90° relative phase) in a visually guided unimanual task. We determined learning rates to quantify changes in learning with age and to determine at what ages the changes occur. We found, as before, that learning rates of participants in their 70 s and 80 s were half those of participants in their 20 s. We also found a gradual slow decline in learning rate with age until approximately age 50, when there was a sudden drop to a reduced learning rate for the 60 though 80 year olds. We discuss possible causes for the “50 s cliff” in perceptuo-motor learning rates and suggest that age related deficits in perception of complex motions may be the key to understanding this result.  相似文献   
995.
996.
A new method of modulated kinesotherapy (MK) involving foot-paced movement (walking and running) with the pace and heart rate synchronized by means of a specially developed Marafon training device is described. In healthy subjects and patients with coronary disease complicated by functional class I or II (FC I–II) angina, the heart rate (HR) decreased by 20–25% during the MK; after the MK, the period of normalization of the HR decreased by 30%, relative to the control. The double product index, an integral representation of the circulatory efficiency, decreased by 15–20%. Normalization of the systolic component (on the average, 62.4 and 64.2% increase in the stroke volume and the end-diastolic volume, respectively) and diastolic function (40 and 43% increase in the peak left ventricular early filling rate and the ratio of the peak early filling rate to the atrial filling rate, respectively) was observed. The indications for and the contraindications to the MK application are specified.  相似文献   
997.
998.
999.
1000.
Acid soluble rat-tail tendon collagen was prepared from animals rendered diabetic by treatment with either streptozotocin or alloxan and from matched controls. In comparison to the normal, the diabetic collagens consistently demonstrated decreased solubility of reconstituted fibrils, marked increase in intrinsic viscosity and a decreased ratio of alpha to beta components. Electrophoresis in sodium dodecyl sulfate-polyacrylamide gels revealed a marked decrease in migration of alpha1, alpha2, and beta components from both types of diabetic collagen. These data indicate that diabetic collagens are larger than normal and are capable of higher degrees of polymerization due to increased intra- and inter-molecular interactions. These changes could explain, in part, the altered response of diabetic connective tissues to inflammation and trauma.  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