全文获取类型
收费全文 | 4602篇 |
免费 | 106篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 98篇 |
综合类 | 11篇 |
化学工业 | 849篇 |
金属工艺 | 100篇 |
机械仪表 | 75篇 |
建筑科学 | 220篇 |
矿业工程 | 18篇 |
能源动力 | 63篇 |
轻工业 | 388篇 |
水利工程 | 47篇 |
石油天然气 | 8篇 |
无线电 | 426篇 |
一般工业技术 | 672篇 |
冶金工业 | 1281篇 |
原子能技术 | 39篇 |
自动化技术 | 417篇 |
出版年
2022年 | 38篇 |
2021年 | 49篇 |
2019年 | 41篇 |
2018年 | 51篇 |
2017年 | 42篇 |
2016年 | 69篇 |
2015年 | 61篇 |
2014年 | 63篇 |
2013年 | 188篇 |
2012年 | 105篇 |
2011年 | 162篇 |
2010年 | 116篇 |
2009年 | 130篇 |
2008年 | 148篇 |
2007年 | 148篇 |
2006年 | 147篇 |
2005年 | 122篇 |
2004年 | 128篇 |
2003年 | 119篇 |
2002年 | 105篇 |
2001年 | 83篇 |
2000年 | 95篇 |
1999年 | 102篇 |
1998年 | 215篇 |
1997年 | 158篇 |
1996年 | 133篇 |
1995年 | 95篇 |
1994年 | 83篇 |
1993年 | 93篇 |
1992年 | 60篇 |
1991年 | 48篇 |
1990年 | 59篇 |
1989年 | 68篇 |
1988年 | 55篇 |
1987年 | 51篇 |
1986年 | 55篇 |
1985年 | 61篇 |
1984年 | 77篇 |
1983年 | 71篇 |
1982年 | 51篇 |
1981年 | 55篇 |
1980年 | 62篇 |
1979年 | 48篇 |
1978年 | 58篇 |
1977年 | 61篇 |
1976年 | 97篇 |
1975年 | 47篇 |
1974年 | 41篇 |
1972年 | 43篇 |
1971年 | 42篇 |
排序方式: 共有4712条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Hans-Jürgen Odenthal Herbert Pfeifer Ina Lemanowicz Rainer Gorissen 《Metallurgical and Materials Transactions B》2002,33(2):163-172
The present work describes quantitative digital particle image velocimetry measurements of a full-scale water model of a thin
slab mold. Different casting speeds and two submerged entry nozzles with one and two outlet ports have been investigated.
The flow pattern of the single-port nozzle shows a counterclockwise-rotating double vortex that is nearly steady-state but
leads to high stationary surface waves. The flow jets out of the two-port nozzle oscillate and produce a transient flow pattern
with low wave amplitudes. The amplitudes for the one-port nozzle show a linear variation with the volumetric flow rate. The
experimental results lead to a good interpretation of the flow phenomena and are used to validate steady-state numerical simulations
with the commercial program, CFX, on the basis of the Reynolds equations. To describe anisotropic turbulence effects, the
Reynolds stress model (RSM) is used for the flat single-port nozzle and the standard k-ɛ model for the mold flow. The calculated mean velocities and wave amplitudes, predicted from pressure distribution at the
water surface, are generally in the consensus of the experimental data.
An erratum to this article is available at . 相似文献
6.
7.
8.
An innovative method for modelling biological processes under anaerobic conditions is presented and discussed. The method is based on titrimetric and off-gas measurements. Titrimetric data is recorded as the addition rate of hydroxyl ions or protons that is required to maintain pH in a bioreactor at a constant level. An off-gas analysis arrangement measures, among other things, the transfer rate of carbon dioxide. The integration of these signals results in a continuous signal which is solely related to the biological reactions. When coupled with a mathematical model of the biological reactions, the signal allows a detailed characterisation of these reactions, which would otherwise be difficult to achieve. Two applications of the method to the enhanced biological phosphorus removal processes are presented and discussed to demonstrate the principle and effectiveness of the method. 相似文献
9.
The vicissitudes of the Israeli-Palestinian peace process since 1967 are analyzed using attitudes and related concepts where relevant. The 1967 war returned the two peoples' zero-sum conflict around national identity to its origin as a conflict within the land both peoples claim. Gradually, new attitudes evolved regarding the necessity and possibility of negotiations toward a two-state solution based on mutual recognition, which became the building stones of the 1993 Oslo agreement. Lacking a commitment to a final outcome, the Oslo-based peace process was hampered by reserve options, which increased avoidance at the expense of approach tendencies as the parties moved toward a final agreement. The resulting breakdown of the process in 2000 produced clashing narratives, reflecting different anchors for judgment and classical mirror images. Public support for violence increased, even as public opinion continued to favor a negotiated two-state solution. Reviving the peace process requires mutual reassurance about the availability of a partner for negotiating a principled peace based on a historic compromise that meets the basic needs and validates the identities of both peoples. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
We investigated changes in the anterior tibial muscle during lengthening of the lower leg in rabbits. In 37 rabbits, an osteotomy of the right middle tibia was performed and was fixed by a unilateral external fixator. The rabbits were randomized into 6 groups. In groups 1, 2, and 3 the tibiae were distracted 0.5 mm/day. In groups 1 and 2, the rabbits were killed after 14 and 28 days of distraction, respectively, and in group 3 after 28 days of distraction, followed by 14 days of rest. Groups 1a, 2a, and 3a served as controls. They were treated similarly as groups 1, 2, and 3, but no distraction was performed. Proliferating cell nuclei were labeled with 5-bromo-2-deoxyuridine and were identified by immunohistochemical staining. The weight of the muscle was measured. During bone lengthening the muscle showed signs of growth, as indicated by increasing weight and number of proliferating cell nuclei. This was observed only during lengthening and it ceased when the lengthening was stopped. 相似文献