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   1626篇
  免费   28篇
电工技术   23篇
综合类   1篇
化学工业   264篇
金属工艺   27篇
机械仪表   15篇
建筑科学   40篇
矿业工程   1篇
能源动力   18篇
轻工业   71篇
水利工程   13篇
无线电   124篇
一般工业技术   225篇
冶金工业   564篇
原子能技术   8篇
自动化技术   260篇
  2020年   16篇
  2018年   21篇
  2017年   16篇
  2016年   14篇
  2015年   15篇
  2014年   16篇
  2013年   53篇
  2012年   46篇
  2011年   61篇
  2010年   42篇
  2009年   35篇
  2008年   53篇
  2007年   60篇
  2006年   45篇
  2005年   30篇
  2004年   25篇
  2003年   37篇
  2002年   32篇
  2001年   31篇
  2000年   30篇
  1999年   36篇
  1998年   125篇
  1997年   106篇
  1996年   66篇
  1995年   42篇
  1994年   50篇
  1993年   51篇
  1992年   25篇
  1991年   21篇
  1989年   15篇
  1988年   19篇
  1987年   16篇
  1986年   13篇
  1985年   14篇
  1984年   18篇
  1983年   14篇
  1982年   20篇
  1981年   21篇
  1980年   15篇
  1979年   13篇
  1978年   14篇
  1977年   24篇
  1976年   48篇
  1974年   16篇
  1973年   13篇
  1972年   16篇
  1971年   14篇
  1970年   13篇
  1969年   19篇
  1968年   13篇
排序方式: 共有1654条查询结果,搜索用时 62 毫秒
991.
This study examined the extent to which the validity scales of the Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A; J. N. Butcher et al., 1992) could differentiate between correctional adolescents instructed to fake good and both correctional and noncorrectional adolescents who received standard instructions. The noncorrectional participants (n?=?137) were from settings not connected with treatment or correctional facilities. Correctional participants (n?=?140) were from a facility in Northeastern Ohio. Mean profiles resembled those previously reported for adults on the MMPI and MMPI-2 and for adolescents on the MMPI and MMPI-A. It was possible to differentiate between (a) correctional youth instructed to fake good and noncorrectional youth with standard instructions and (b) correctional youth who were faking and correctional youth with standard instructions. Slightly different cutoff scores were needed for these two discriminations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
992.
Forskolin and dibutyryl cyclic adenosine monophosphate (cAMP) stimulate force of contraction independent of beta-adrenoceptor stimulation. We studied their effects on force of contraction and phosphorylation of regulatory proteins in isolated electrically driven trabeculae carneae from failing human ventricles. The phosphorylation state of the regulatory protein phospholamban was studied because its phosphorylation usually faithfully follows contractility. For comparison, the phosphorylation state of the inhibitory subunit of troponin was studied. The phosphorylation state was inferred from in vitro phosphorylation of homogenates with cAMP-dependent protein kinase in the presence of radioactive gamma[32P]ATP Proteins were separated by electrophoresis, and radioactivity in the proteins of interest was quantified. The maximal positive inotropic effects occurred at 30 microM forskolin and were attenuated in comparison with the maximal effects to dibutyryl cAMP (1 mM). Both forskolin and dibutyryl cAMP enhanced phospholamban phosphorylation. However, phospholamban phosphorylation in intact trabeculae treated with 30 microM forskolin and 1 mM dibutyryl cAMP was comparable. It is suggested that phospholamban phosphorylation can be dissociated from inotropy at least in isolated trabeculae from failing human hearts.  相似文献   
993.
Allogeneic and autologous marrow transplants are routinely used to correct a wide variety of diseases. In addition, autologous marrow transplants potentially provide opportune means of delivering genes in transfected, engrafting stem cells. However, relatively little is known about the mechanisms of engraftment in transplant recipients, especially in the nonablated setting and with regard to cells not of hemopoietic origin. In particular, this includes stromal cells and progenitors of the osteoblastic lineage. We have demonstrated for the first time that a whole bone marrow transplant contains cells that engraft and become competent osteoblasts capable of producing bone matrix. This was done at the individual cell level in situ, with significant numbers of donor cells being detected by fluorescence in situ hybridization in whole femoral sections. Engrafted cells were functionally active as osteoblasts producing bone before being encapsulated within the bone lacunae and terminally differentiating into osteocytes. Transplanted cells were also detected as flattened bone lining cells on the periosteal bone surface.  相似文献   
994.
995.
We have used six static parallelization tools on four Fortran-77 programs used in physics simulations. We indicate areas where current tools have difficulties in recognizing parallelism, and illustrate these issues with simple examples. We suggest that a dynamic dependency analysis tool is needed to aid the user in the parallelization of dusty decks.  相似文献   
996.
997.
In this paper we present two types of local error estimators for the primal finite‐element‐method (FEM) by duality arguments. They are first derived from the (explicit) residual error estimation method (REM) and then—as a new contribution—from the (implicit) posterior equilibrium method (PEM) using improved boundary tractions, gained by local post‐processing with local Neumann problems, with applications in elastic problems. For the displacements a local error estimator with an upper bound is derived and also a local estimator for stresses. Furthermore—for better numerical efficiency—the residua are projected energy‐invariant onto reference elements, where the local Neumann problems have to be solved. Comparative examples between REM‐ and PEM‐type local estimators show superior effectivity indices for the latter one. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
998.
Content and contextual memory for remote public figures and events was assessed with a modified version of the Presidents Test in patients with Alzheimer's disease (AD) or Parkinson's disease (PD). Contributions of executive functioning, semantic memory, and explicit anterograde memory to remote memory abilities were also examined. The AD group had temporally extensive deficits in content and contextual remote memory not accountable for by dementia severity. The PD group did not differ from the control group in remote memory, despite anterograde memory impairment. These results support the position that different component processes characterize remote memory, various mnemonic and nonmnemonic cognitive processes contribute to remote memory performance, and anterograde and remote memory processes are dissociable and differentially disrupted by neurodegenerative disease. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
999.
Studies showing that verbal priming can implicitly affect alcohol consumption have been used to support cognitive models of expectancies. However, because expectancy words reflect affective states as well as drinking outcomes, mediation through an affective pathway remains theoretically plausible (i.e., such words inadvertently may affect mood, which in turn influences drinking). The primary pathway was identified (and expectancy theory was tested) by comparing memory priming (using alcohol expectancy or neutral words) with mood induction (using positive or neutral music); an unrelated experiment paradigm allowed the priming manipulation to implicitly affect drinking. Men in the alcohol priming group drank significantly more than men in each of the other conditions, and, consistent with theory, men with histories of heavier drinking drank the most when primed with alcohol expectancies, indicating that expectancies can function as automatic memory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
1000.
Photoluminescence (PL) spectra of InAs/GaAs heteroepitaxial structures with quantum dots (QDs) have been studied. The structures were grown by submonolayer migration-enhanced epitaxy on vicinal substrates with the amount of deposited InAs close to the critical value of 1.8 monolayer (ML). The origin and evolution of the structure of PL spectra were studied in relation to the direction and angle of misorientation, temperature, and power density and spectrum of the exciting radiation. A blue shift and narrowing of the PL band with increasing misorientation angle was established experimentally. The fact that QDs become smaller and more uniform in size is explained in terms of a lateral confinement of QDs on terraces with account taken of the step bunching effect. The temperature dependences of the positions and full widths at half-maximum (FWHM) of PL bands are fundamentally different for isolated and associated QDs. The exciton ground states contribute to all low-temperature spectral components. The excited exciton state contributes to the recombination emission from QDs, as evidenced by the temperature dependence of the integrated intensity of the PL bands. A quantitative estimate is given of the electronic structure of different families of InAs QDs grown on GaAs substrates misoriented by 7° in the [001] direction.  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