全文获取类型
收费全文 | 2473篇 |
免费 | 184篇 |
国内免费 | 54篇 |
专业分类
电工技术 | 49篇 |
综合类 | 90篇 |
化学工业 | 723篇 |
金属工艺 | 34篇 |
机械仪表 | 47篇 |
建筑科学 | 147篇 |
矿业工程 | 14篇 |
能源动力 | 61篇 |
轻工业 | 418篇 |
水利工程 | 26篇 |
石油天然气 | 179篇 |
武器工业 | 23篇 |
无线电 | 38篇 |
一般工业技术 | 566篇 |
冶金工业 | 45篇 |
原子能技术 | 12篇 |
自动化技术 | 239篇 |
出版年
2024年 | 5篇 |
2023年 | 36篇 |
2022年 | 42篇 |
2021年 | 38篇 |
2020年 | 73篇 |
2019年 | 77篇 |
2018年 | 82篇 |
2017年 | 89篇 |
2016年 | 101篇 |
2015年 | 77篇 |
2014年 | 127篇 |
2013年 | 172篇 |
2012年 | 143篇 |
2011年 | 145篇 |
2010年 | 110篇 |
2009年 | 131篇 |
2008年 | 99篇 |
2007年 | 151篇 |
2006年 | 140篇 |
2005年 | 124篇 |
2004年 | 113篇 |
2003年 | 105篇 |
2002年 | 77篇 |
2001年 | 80篇 |
2000年 | 67篇 |
1999年 | 59篇 |
1998年 | 59篇 |
1997年 | 47篇 |
1996年 | 38篇 |
1995年 | 28篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1967年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有2711条查询结果,搜索用时 0 毫秒
131.
The use of animals in research has always been a debatable issue. Over the past few decades, efforts have been made to reduce, replace, and refine experiments for ethical use of experimental animals. The use of chick chorioallantoic membrane (CAM) was one of the proposed alternatives to the Draize rabbit ocular irritation test with several advantages including simplicity, rapidity, sensitivity, ease of performance, and cost-effectiveness. The recent use of CAM in the development of pharmaceuticals and testing models to mimic human tissue, including drug transport across CAM, will be discussed in this review. 相似文献
132.
《Drug development and industrial pharmacy》2013,39(5):816-824
Many of the increasing number of intranasal products available for either local or systemic action can be considered sub-optimal, most notably where nasal drip or run-off give rise to discomfort/tolerability issues or reduced/variable efficacy. PecSys, an in situ gelling technology, contains low methoxy (LM) pectin which gels due to interaction with calcium ions present in nasal fluid. PecSys is designed to spray readily, only forming a gel on contact with the mucosal surface. The present study employed two in vitro models to confirm that gelling translates into a reduced potential for drip/run-off: (i) Using an inclined TLC plate treated with a simulated nasal electrolyte solution (SNES), mean drip length [±SD, n = 10] was consistently much shorter for PecSys (1.5?±?0.4?cm) than non-gelling control (5.8?±?1.6?cm); (ii) When PecSys was sprayed into a human nasal cavity cast model coated with a substrate containing a physiologically relevant concentration of calcium, PecSys solution was retained at the site of initial deposition with minimal redistribution, and no evidence of run-off/drip anteriorly or down the throat. In contrast, non-gelling control was significantly more mobile and consistently redistributed with run-off towards the throat. Conclusion: In both models PecSys significantly reduced the potential for run-off/drip ensuring that more solution remained at the deposition site. In vivo, this enhancement of retention will provide optimum patient acceptability, modulate drug absorption and maximize the ability of drugs to be absorbed across the nasal mucosa and thus reduce variability in drug delivery. 相似文献
133.
A case formulation, for a client with depression, based on emotion-focused therapy treatment principles will be presented. The client was seen for 16 sessions in emotion-focused therapy. Based on information provided in the first interview, the therapist discusses how the client’s issues can be formulated in an emotion-focused treatment by attending to different process markers, including markers of characteristic styles of being or ways of treating the self and emotional experience; modes of engagement or ways that emotional experience is processed in terms of whether it is overregulated or underregulated; specific in-session tasks like focusing, two-chair or empty chair work; and micromarkers of nonverbal behaviors including vocal quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
134.
The complexity of a standard compact-in-form Lagrangian dynamical expression is proportional to the fourth power of the number of degrees of freedom (DOF) of a robotic system. This fact challenges both simulation and control of robots with hyper degrees of freedom. In this paper, a systematic approach for deriving the dynamical expression of so-called general constrained robots is proposed. This proposed approach has two main features. First, it uses the subsystem dynamics such as the dynamics of joints and rigid links to construct the dynamical expression of the entire robotic system in a closed form. The complexity of the resulted dynamic expression is linearly proportional to the number of DOF of a robotic system. Second, it extends the standard dynamical form and properties of the conventional single-arm constrained robots to a class of more general robotic systems including the coordinated multiple-arm robotic systems. Three spaces, namely the general joint space, the general task space, and the extended subsystems space, are connected through corresponding velocity/force mapping matrices.An erratum to this article can be found at 相似文献
135.
Karol Mikula Alessandro Sarti Fiorella Sgallari 《Computing and Visualization in Science》2006,9(1):23-31
We introduce semi-implicit complementary volume numerical scheme for solving the level setformulation of Riemannian mean curvature
flow problem arising in image segmentation, edge detection, missing boundary completion and subjective contour extraction.
The scheme is robust and efficient since it is linear, and it is stable in L_∞ and weighted W
1,1 sense without any restriction on a time step. The computational results related to medical image segmentation with partly
missing boundaries and subjective contours extraction are presented. 相似文献
136.
油气储层流动单元划分标准的探讨 总被引:8,自引:0,他引:8
根据对大量岩心样品的统计分析,研究了流动层指数(flow zone idex,Ifz)的基础定义和物理意义.结果认为:Ifz值相近的岩心样品具有较大的孔隙度和大的渗透率变化范围,但不一定属于同一类流动单元.Ifz值并不能准确的表征影响流体流动的岩石物理性质,单纯采用Ifz值作为划分储层流动单元的标准是值得商榷的.采用渗透率、层内渗透率纵向非均质参数(变异系数、突进系数、极差)、孔隙度和束缚水饱和度等参数作为标准划分流动单元并应用该方法研究了蒙古林砾岩油藏储层,结果表明:这些参数能够较为准确的描述储层内部油水运动规律相似的储集带. 相似文献
137.
138.
Ping Gao 《Information Systems Journal》2005,15(3):255-275
Abstract. Drawing upon actor-network theory, this article analyses the socio-technological construction of China's strategy for the telecommunications market transformation. We define the telecommunications market as the non-human actor. The public and society, the state, and the operators constitute three groups of human actors representing the social interests in the telecommunications industry. We have observed that these actors' interests are influenced by the situation of technology advance, the telecommunications development level, the macro reform progress and the national policies concerning the political and economic systems, and the international trend in telecommunications reforms. Owing to the dynamics of these contextual elements and the struggle of actors to inscribe their interests into the national strategy, China has transformed the telecommunications market by four stages, each stage with specific foci. Our case study demonstrates that the applications of actor-network theory can be extended to investigate the formulation of a national strategy. The research design in which the social and technological contexts are dynamically connected with strategy formulation can be drawn upon by other actor-network studies. 相似文献
139.
介绍了大空间气流组织设计中主要的三种方法,即计算公式法、数值模拟法和模型实验法,同时分析它们的优缺点并介绍一种综合应用的方法. 相似文献
140.
用 2 b方程证明移源法 ,并得出它的推论 ;在此基础上 ,给出了移源法的新应用——消去受控源 相似文献