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   20316篇
  免费   1101篇
  国内免费   41篇
电工技术   105篇
综合类   119篇
化学工业   5124篇
金属工艺   377篇
机械仪表   302篇
建筑科学   563篇
矿业工程   47篇
能源动力   573篇
轻工业   4136篇
水利工程   151篇
石油天然气   149篇
武器工业   1篇
无线电   737篇
一般工业技术   2419篇
冶金工业   4413篇
原子能技术   98篇
自动化技术   2144篇
  2024年   40篇
  2023年   169篇
  2022年   690篇
  2021年   818篇
  2020年   469篇
  2019年   545篇
  2018年   632篇
  2017年   635篇
  2016年   693篇
  2015年   524篇
  2014年   802篇
  2013年   1379篇
  2012年   1192篇
  2011年   1301篇
  2010年   983篇
  2009年   925篇
  2008年   815篇
  2007年   699篇
  2006年   554篇
  2005年   467篇
  2004年   411篇
  2003年   434篇
  2002年   341篇
  2001年   265篇
  2000年   211篇
  1999年   301篇
  1998年   1489篇
  1997年   918篇
  1996年   638篇
  1995年   355篇
  1994年   309篇
  1993年   281篇
  1992年   82篇
  1991年   66篇
  1990年   63篇
  1989年   69篇
  1988年   76篇
  1987年   71篇
  1986年   45篇
  1985年   56篇
  1984年   34篇
  1983年   32篇
  1982年   40篇
  1981年   34篇
  1980年   58篇
  1979年   21篇
  1978年   26篇
  1977年   90篇
  1976年   229篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
51.
This study examined the mediating role of service climate in the prediction of employee performance and customer loyalty. Contact employees (N=342) from 114 service units (58 hotel front desks and 56 restaurants) provided information about organizational resources, engagement, and service climate. Furthermore, customers (N=1,140) from these units provided information on employee performance and customer loyalty. Structural equation modeling analyses were consistent with a full mediation model in which organizational resources and work engagement predict service climate, which in turn predicts employee performance and then customer loyalty. Further analyses revealed a potential reciprocal effect between service climate and customer loyalty. Implications of the study are discussed, together with limitations and suggestions for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
53.
Some sufficient conditions concerning stability of solutions of stochastic differential evolution equations with general decay rate are first proved. Then, these results are interpreted as suitable stabilization ones for deterministic and stochastic systems. Also, they permit us to construct appropriate linear stabilizers in some particular situations.  相似文献   
54.
55.
采用Gaussian 03在B3LYP/6-31G(d)水平上分别优化新型多苯并咪唑环芳(MBICP)受体和氨基酸甲酯(AAME)配体,再用基于模拟退火的分子动力学方法 CDOCKER将配体与受体对接,对每一个复合物获得了一组最低能量的初始构象。最后用Turbomole在BLYP/def-TZVP水平对初始构象进一步优化,并对收敛后的复合物最低能量构象作NBO分析。以密度泛函理论计算获得的相互作用能作为核心参数,采用组合策略建立了表达MBICP-AAME复合物结合常数的定量关系模型,计算了该类复合物的结合常数。对MBICP受体和AAME配体间的作用模式以及影响MBICP受体识别AAME配体的主要因素,作了深入讨论。  相似文献   
56.
The distribution of the protein energy ratio indicators (Pe%), amino acid score and protein value (NDpCal%) in the three daily meals (breakfast, lunch and dinner) of the diet of pregnant women from Santa María Cauqué, Guatemala, was studied. The results were compared with those obtained for the total daily food intake. The differences observed were not significant, confirming the validity of the determination of amino acid score, Pe% and NDpCal% in the foods consumed during the whole day in this type of populations. It also reflects the nutritional benefit of the food pattern, since protein utilization would not be decreased by a different distribution of protein quality and concentration throughout the three daily meals. The variability among individuals of Pe% intake, amino acid score and NDpCal% gave the following values: 16.0, 9.3 and 15.6, respectively. It is noteworthy to add that the variability of Pe% observed is similar to that reported for populations of developed countries.  相似文献   
57.
A study has been made of the elastic behaviour of Polyvinylchloride commercial samples at high shear stresses, under similar conditions to those used in the processing industry, by means of an extrusion capillary rheometer.The influence in the die swell of variables as molecular weight, temperature and shear rate has been studied. Results are in agreement with general literature data.Smooth extrudates are obtained only in the zone of intermediate shear rates. In this zone it is observed that the die swell increases with shear rate.  相似文献   
58.
59.
The Principal Component Regression model of multiple responses is extended to forccast a continuous-time stochastic process. Orthogonal projection on a subspace of trigonometric functions is applied in order to estimate the principal components using discrete-time observations from a sample of regular curves. The forecasts provided by this approach are compared with classical principal component regression on simulated data.  相似文献   
60.
Immunotherapy has brought hope to the fight against glioblastoma, but its efficacy remains unclear. We present the case of CST, a 25-year-old female patient with a large right-hemisphere glioblastoma treated with a dendritic–tumor cell fusion vaccine. CST showed a near-complete tumor response, with a marked improvement in her functional status and simultaneous increases in tumor-specific CD8+ and CD4+ T cells. Two months before recurrence, the frequency of tumor-specific T cells decreased, while that of IL-17 and CD4+ T cells increased. CST passed away 15 months after enrollment. In this illustrative case, the tumor-specific CD4+ T-cell numbers and phenotype behaved as treatment efficacy biomarkers, highlighting the key role of the latter in glioblastoma immunotherapy.  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