全文获取类型
收费全文 | 5871篇 |
免费 | 223篇 |
国内免费 | 139篇 |
专业分类
电工技术 | 177篇 |
技术理论 | 5篇 |
综合类 | 736篇 |
化学工业 | 887篇 |
金属工艺 | 438篇 |
机械仪表 | 267篇 |
建筑科学 | 705篇 |
矿业工程 | 370篇 |
能源动力 | 124篇 |
轻工业 | 698篇 |
水利工程 | 110篇 |
石油天然气 | 262篇 |
武器工业 | 25篇 |
无线电 | 103篇 |
一般工业技术 | 306篇 |
冶金工业 | 604篇 |
原子能技术 | 17篇 |
自动化技术 | 399篇 |
出版年
2024年 | 4篇 |
2023年 | 29篇 |
2022年 | 55篇 |
2021年 | 83篇 |
2020年 | 83篇 |
2019年 | 71篇 |
2018年 | 54篇 |
2017年 | 72篇 |
2016年 | 110篇 |
2015年 | 135篇 |
2014年 | 300篇 |
2013年 | 230篇 |
2012年 | 376篇 |
2011年 | 417篇 |
2010年 | 318篇 |
2009年 | 347篇 |
2008年 | 232篇 |
2007年 | 414篇 |
2006年 | 431篇 |
2005年 | 346篇 |
2004年 | 294篇 |
2003年 | 283篇 |
2002年 | 288篇 |
2001年 | 239篇 |
2000年 | 224篇 |
1999年 | 168篇 |
1998年 | 120篇 |
1997年 | 95篇 |
1996年 | 95篇 |
1995年 | 49篇 |
1994年 | 59篇 |
1993年 | 44篇 |
1992年 | 23篇 |
1991年 | 14篇 |
1990年 | 22篇 |
1989年 | 19篇 |
1988年 | 4篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1963年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有6233条查询结果,搜索用时 15 毫秒
1.
M. R. Thompson 《Drug development and industrial pharmacy》2015,41(8):1223-1231
Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique. 相似文献
2.
The paper considers the problem of stabilization of systems possessing a multiple zero eigenvalue at the origin. The controller that we propose, uses multiple delayed measurements instead of derivative terms. Doing so, we increase the performances of the closed loop in presence of system uncertainties and/or noisy measurements. The problem formulation and the analysis is presented through a classical engineering problem which is the stabilization of an inverted pendulum on a cart moving horizontally. On one hand, we perform a nonlinear analysis of the center dynamics described by a three dimensional system of ordinary differential equations with a codimension-three triple zero bifurcation. On the other hand, we present the complementary stability analysis of the corresponding linear time invariant system with two delays describing the behavior around the equilibrium. The aim of this analysis is to characterize the possible local bifurcations. Finally, the proposed control scheme is numerically illustrated and discussed. 相似文献
3.
The time window for effective climate change mitigation is closing. Technological change needs to be accelerated to limit global warming to a manageable level. Path dependence of technological change is one explanation for sluggish diffusion of green technologies. Firms acquire capital that differs by technology type and build up type-specific technological know-how needed to use capital efficiently. Path dependence emerges from cumulative knowledge stocks manifested in the productivity of supplied capital and firms’ capabilities. Increasing returns arise from induced innovation feedbacks and learning by doing. Relatively lower endowments with technological knowledge are a barrier to diffusion for new technologies. This paper shows how the evolution of relative stocks of technological knowledge explains different shapes of diffusion curves. Using an eco-technology extension of the macroeconomic agent-based model Eurace@unibi, it is shown how the effectiveness of different climate policies depends on the type and strength of diffusion barriers. Environmental taxes can outweigh lower productivity and subsidies perform better if lacking capabilities hinder firms to adopt a sufficiently mature technology. 相似文献
4.
In this article, the authors study the factorial structure of 2 versions (64 items and 32 items) of the Dutch translation of the Inventory of Interpersonal Problems (IIP; L. M. Horowitz, L. E. Alden, J. S. Wiggins, & A. L. Pincus, 2000) in both a clinical sample (n = 382) and a student sample (n = 287). First, the authors test whether both inventories are constituted by correlated uni-dimensional subscales, and they conclude that this is true only for the short version. Second, the authors study whether the correlations between the subscales follow a circumplex pattern. This proves to be true for both versions. Coefficients alpha and correlations between the IIP-64 and IIP-32 subscales are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
From its foundation until 2004, ETRI has registered over 1,000 US patents. This letter analyzes the characteristics of these patents and addresses the explanatory factors affecting their citation counts. For explanatory variables, research team related variables, invention specific variables, and geographical domain related variables are suggested. Zero‐altered count data models are used to test the impact of independent variables. A key finding is that technological cumulativeness, the scale of invention, outputs in the electronic field, and the degree of dependence on the US technology domain positively affect the citation counts of ETRI‐invented US patents. The magnitude of international presence appears to negatively affect the citation counts of ETRI‐invented US patents. 相似文献
6.
介绍了铁路电力试验车软件的设计思想、框架结构及其总体控制策略 ,并就其中的测试程序、数据库管理系统、串口通讯程序、复杂式样报表生成和系统安装程序的设计策略作了叙述。 相似文献
7.
位山引黄灌区泥沙淤积原因及处理对策 总被引:7,自引:2,他引:5
位山灌区是黄河下游大型引黄灌区 ,渠系泥沙淤积严重 ,泥沙处理困难。通过采用远距离输沙、集中处理沉沙区泥沙、分散沉沙和节水减淤等技术措施 ,减少了渠系的泥沙淤积。对清淤产生的泥沙 ,采取综合开发利用的技术和管理措施 ,取得了比较可靠的效果。 相似文献
8.
9.
从原料与生产工艺过程分析了瓷质势光砖批量色差产生的原因,并提出了相应对策,为生产质量佳化提供一定的参考。 相似文献
10.
实施油气回收的必要性和技术方案的探讨 总被引:8,自引:0,他引:8
郝保良 《石油化工管理干部学院学报》2002,(2):41-42,69
简要介绍油气回收技术;从环保和增加经济效益的角度,以福建炼化公司的实际情况为例提出了油气回收的方案,并对实行该方案的必要性和经济效益做了分析;希望增强炼化企业对油气回收问题的重视,达到安全生产、改善环境和节约能源的目的。 相似文献