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   9297篇
  免费   105篇
  国内免费   6篇
教育   6208篇
科学研究   1104篇
各国文化   323篇
体育   712篇
综合类   4篇
文化理论   63篇
信息传播   994篇
  2021年   88篇
  2020年   124篇
  2019年   172篇
  2018年   216篇
  2017年   240篇
  2016年   215篇
  2015年   145篇
  2014年   181篇
  2013年   1612篇
  2012年   192篇
  2011年   194篇
  2010年   174篇
  2009年   174篇
  2008年   229篇
  2007年   211篇
  2006年   177篇
  2005年   167篇
  2004年   179篇
  2003年   123篇
  2002年   114篇
  2001年   153篇
  2000年   184篇
  1999年   160篇
  1998年   86篇
  1997年   85篇
  1996年   75篇
  1994年   68篇
  1993年   81篇
  1992年   138篇
  1991年   147篇
  1990年   149篇
  1989年   156篇
  1988年   120篇
  1987年   117篇
  1986年   116篇
  1985年   157篇
  1984年   126篇
  1983年   118篇
  1982年   99篇
  1981年   80篇
  1980年   91篇
  1979年   142篇
  1978年   89篇
  1977年   90篇
  1976年   78篇
  1975年   78篇
  1974年   88篇
  1973年   82篇
  1971年   74篇
  1968年   75篇
排序方式: 共有9408条查询结果,搜索用时 15 毫秒
171.
The Journal of the Medical Library Association (JMLA) selects new editorial board members every year. In the spring of 2021, JMLA used a new process for reviewing and selecting applicants for the limited number of open editorial board positions. This reevaluation of the selection process was spurred by a desire to create a more diverse and representative board. Changes to the procedures for selecting new editorial board members included having an open call for editorial board members, creating an application form, creating a selection committee to screen applicants, creating a form for the selection committee to extract data from applications, and creating a two-step process for screening and then selecting board members. As part of construction of this new process, areas for continued improvement were also identified, such as refining the application form to allow more specific answers to areas of interest to the selection committee. The newly created selection process for editorial board members constitutes a significant change in JMLA processes; however, more can be done to build on this work by further refining the selection process and ensuring that new members are selected in a transparent and streamlined manner.  相似文献   
172.
Understanding the mineralogy of the Earth''s interior is a prerequisite for unravelling the evolution and dynamics of our planet. Here, we conducted high pressure-temperature experiments mimicking the conditions of the deep lower mantle (DLM, 1800–2890 km in depth) and observed surprising mineralogical transformations in the presence of water. Ferropericlase, (Mg, Fe)O, which is the most abundant oxide mineral in Earth, reacts with H2O to form a previously unknown (Mg, Fe)O2Hx (x ≤ 1) phase. The (Mg, Fe)O2Hx has a pyrite structure and it coexists with the dominant silicate phases, bridgmanite and post-perovskite. Depending on Mg content and geotherm temperatures, the transformation may occur at 1800 km for (Mg0.6Fe0.4)O or beyond 2300 km for (Mg0.7Fe0.3)O. The (Mg, Fe)O2Hx is an oxygen excess phase that stores an excessive amount of oxygen beyond the charge balance of maximum cation valences (Mg2+, Fe3+ and H+). This important phase has a number of far-reaching implications including extreme redox inhomogeneity, deep-oxygen reservoirs in the DLM and an internal source for modulating oxygen in the atmosphere.  相似文献   
173.
174.
175.
176.
During soccer matches, performance decrements have been reported that relate to both physical abilities and technical skills. To investigate the effects of low-frequency electrical stimulation LFES (VeinoplusSport®, Ad Rem Technology, France) administered during half-time recovery on performance alterations during the second half. Twenty-two highly trained young players undertook a soccer-match simulation (SAFT90). During half-time, they were randomly assigned to LFES group or Placebo group. Each half was split into 3 bouts of 12 minutes. Following each bout, maximal strike speed (MSS), sprint test (ST), maximal sprint accelerations (MA) and metabolic power (MP) were determined in both groups. Arterial (AF) and venous flows (VF) were measured at rest and at the end of half-time. LEFS group exhibited beneficial effects on performance compared to the Placebo group with a likely effect for MSS, ST, MA, and a possible effect for MP. AF and VF increased statistically more in LEFS group compared to Placebo group. The use of specific calf-pump LFES during half-time of a youth simulated soccer match attenuated the decrease in performance during the second half compared to Placebo group. This effect is most marked at the beginning of the second half with regards to explosive parameters.  相似文献   
177.
178.
The lower limb kinetics of curve sprinting in amputees are not well described in the literature, particularly with respect to the effect of the side of amputation. This is an issue due to the importance of the knowledge for prosthetic design and classification of athletes. Thus, the aim of this study was to investigate the influence of side of amputation on curve sprinting performance in athletes with a unilateral leg amputation. A three-dimensional motion analysis system (Vicon), four force plates (Kistler) and a modified mathematical human model (ALASKA) were used to compare clockwise and counter clockwise curve sprinting lower limb kinematics and kinetics of a Paralympic medalist with a left-sided knee exarticular amputation. Results reveal that vertical ground reaction force application and total vertical impulse were lower when the affected limb was at the inside of the curve. The unaffected limb showed joint mechanics different to those established for non-amputee athletes and might contribute better to propulsion when being the inside limb. Curve sprinting biomechanics and the ability to attain high radial velocities are directly dependent on the side of amputation relative to the curve direction in a unilateral amputee athlete of highest performance level.  相似文献   
179.
This study investigated patterns of Bannatyne's recategorized WISC-R scores of 146 predominantly Tlingit Indian children who were referred for psychoeducational testing. The students were divided into two groups, ages 6 through 10 and 11 through 16, in order to investigate patterns that occurred at each level and to investigate the proportions that exhibited a typically “Indian” pattern: Spatial > Sequential > Conceptual and Acquired Knowledge. As a group, the older children displayed an Indian pattern, but the younger children displayed a different one: Spatial > Conceptual and Sequential > Acquired Knowledge. Both groups, however, displayed a significantly greater proportion of children with an Indian pattern than would be expected by chance. A considerable number of individuals from both groups attained significant differences among scores in the Indian direction.  相似文献   
180.
Form A of the Boehm Test of Basic Concepts (BTBC) was administered to 180 kindergartners—90 boys and 90 girls. Neither their mean scores nor their standard deviations differed significantly, and the distributions of scores for the two groups were virtually identical. Moreover, the application of three internal criteria for bias yielded totally negative results; thus, there was no evidence of either sex differences or sex bias in the data.  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