全文获取类型
收费全文 | 3115篇 |
免费 | 58篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 35篇 |
综合类 | 1篇 |
化学工业 | 435篇 |
金属工艺 | 47篇 |
机械仪表 | 58篇 |
建筑科学 | 148篇 |
矿业工程 | 135篇 |
能源动力 | 48篇 |
轻工业 | 262篇 |
水利工程 | 35篇 |
石油天然气 | 7篇 |
无线电 | 244篇 |
一般工业技术 | 399篇 |
冶金工业 | 822篇 |
原子能技术 | 24篇 |
自动化技术 | 474篇 |
出版年
2023年 | 15篇 |
2022年 | 25篇 |
2021年 | 33篇 |
2020年 | 30篇 |
2019年 | 47篇 |
2018年 | 48篇 |
2017年 | 46篇 |
2016年 | 56篇 |
2015年 | 46篇 |
2014年 | 68篇 |
2013年 | 166篇 |
2012年 | 94篇 |
2011年 | 163篇 |
2010年 | 103篇 |
2009年 | 135篇 |
2008年 | 112篇 |
2007年 | 115篇 |
2006年 | 111篇 |
2005年 | 97篇 |
2004年 | 93篇 |
2003年 | 80篇 |
2002年 | 80篇 |
2001年 | 64篇 |
2000年 | 50篇 |
1999年 | 60篇 |
1998年 | 198篇 |
1997年 | 140篇 |
1996年 | 99篇 |
1995年 | 59篇 |
1994年 | 57篇 |
1993年 | 62篇 |
1992年 | 36篇 |
1991年 | 28篇 |
1990年 | 32篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 34篇 |
1986年 | 29篇 |
1985年 | 36篇 |
1984年 | 25篇 |
1983年 | 21篇 |
1982年 | 32篇 |
1981年 | 29篇 |
1980年 | 28篇 |
1979年 | 20篇 |
1978年 | 21篇 |
1977年 | 30篇 |
1976年 | 47篇 |
1974年 | 11篇 |
1972年 | 14篇 |
排序方式: 共有3174条查询结果,搜索用时 15 毫秒
1.
The author relates his experiences in a small software development company. These experiences show that project management is challenging and if the project manager is an obstacle, the project is bound to fail. When it does, it can spell disaster for the manager and anyone who accompanies him or her on a software development journey. 相似文献
2.
3.
Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank. 相似文献
4.
Jonathan J. Cook 《Software》2004,34(9):815-845
We discuss P#, our implementation of a tool that allows interoperation between a concurrent superset of the Prolog programming language and C#. This enables Prolog to be used as a native implementation language for Microsoft's .NET platform. P# compiles a linear logic extension of Prolog to C# source code. We can thus create C# objects from Prolog and use C#'s graphical, networking and other libraries. We add language constructs on the Prolog side that allow concurrent Prolog code to be written. A primitive predicate is provided that evaluates a Prolog structure on a newly forked thread. Communication between threads is based on the unification of variables contained in such a structure. It is also possible for threads to communicate through a globally accessible table. All of the new features are available to the programmer through new built-in Prolog predicates. We discuss two software engineering tools implemented using P#. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
5.
Aard J. Groen Petra C. De WeerdNederhof Inge C. Kerssensvan Drongelen Rob A.J. Badoux Gerard P.H. Olthuis 《Creativity & Innovation Management》2002,11(1):2-16
In this paper we describe a framework for analysing the creation and justification of Research & Development. The 4S framework is developed for analysing the scope, scale, skills and social network aspects of Research & Development value. The framework is based on social system theory, a process contingency model, and recent Research & Development metrics. We present a first empirical assessment based on a workshop using the 4S framework for leveraging Research & Development. Results that assist in the assessment of value creation utilising R & D within networks are very relevant in high tech industries. The multi–dimensional process approach of this framework seems promising for understanding and managing R&D value creation, but needs further operationalisation. Case studies are described and a Dutch network on leveraging R&D has been initiated. 相似文献
6.
Five percent of children in the United States have asthma. Status asthmaticus is one of the most common conditions for which children seek care in a pediatric emergency department. beta 2-Agonists such as albuterol are the mainstay of emergency therapy for such children. We present a case of a 4-year-old boy who experienced supraventricular tachycardia (SVT) following albuterol therapy. This is believed to be the first report of adenosine being successfully used to treat a child with albuterol-induced SVT. We also briefly review the recognition and management of SVT in children and the pharmacokinetics of and indications for adenosine. 相似文献
7.
Cook R.D. Saulnier G.J. Gisser D.G. Goble J.C. Newell J.C. Isaacson D. 《IEEE transactions on bio-medical engineering》1994,41(8):713-722
Presents the design, implementation, and performance of Rensselaer's third-generation adaptive current tomograph, ACT3. This system uses 32 current sources and 32 phase-sensitive voltmeters to make a 32-electrode system that is capable of applying arbitrary spatial patterns of current. The instrumentation provides 16 b precision on both the current values and the real and reactive voltage readings and can collect the data for a single image in 133 ms. Additionally, the instrument is able to automatically calibrate its voltmeters and current sources and adjust the current source output impedance under computer control. The major system components are discussed in detail and performance results are given. Images obtained using stationary agar targets and a moving pendulum in a phantom as well as in vivo resistivity profiles showing human respiration are shown 相似文献
8.
Robert D. Cook 《Thin》1985,3(4):365-372
A cylindrical tank is mounted with its axis horizontal. Supports on either side run lengthwise. If the tank wall is thin, deformations significantly affect the stresses, so that standard stress formulae (which ignore deformations) may over-estimate stresses by a factor of ten or more. In this paper, deformations are accounted for by a nonlinear analysis. Stresses and deformed shapes are reported for various positions of the supports, radius to thickness ratios, and depths of fill. 相似文献
9.
Document caching and connection caching are extensively studied problems. In document caching, one has to maintain caches
containing documents accessible in a network. In connection caching, one has to maintain a set of open network connections
that handle data transfer. Previous work investigated these two problems separately while in practice the problems occur together:
In order to load a document, one has to establish a connection between network nodes if the required connection is not already
open. In this paper we present the first study that integrates document and connection caching. We first consider a very basic
model in which all documents have the same size and the cost of loading a document or establishing a connection is equal to
1. We present deterministic and randomized online algorithms that achieve nearly optimal competitive ratios unless the size
of the connection cache is extremely small. We then consider general settings where documents have varying sizes. We investigate
a FAULT model in which the loading cost of a document is 1 as well as a BIT model in which the loading cost is equal to the
size of the document. 相似文献
10.
MM Simon P Pavlik A Hartig M Binder H Ruis WJ Cook CL Denis B Schanz 《Canadian Metallurgical Quarterly》1995,249(3):289-296
We examined the hypoxic tolerance phenomenon in vitro. Brief exposure to hypoxia induced the production of basic fibroblast growth factor (bFGF) mRNA and protein in rat cortical neurons and protected them from hypoxic injury. Cortical neurons were cultured from 18th-day rat embryos in a serum-free medium and subjected to brief (4 h) and/or prolonged (24 h) hypoxia. Neuronal damage was assessed by quantifying lactate dehydrogenase (LDH) activity in the medium. After brief hypoxia, LDH release was identical to that of the controls, whereas prolonged hypoxia caused a significant increase in LDH release, indicating neuronal death. However, if brief hypoxia was applied 2 days prior to the prolonged hypoxia, no increase in LDH release was observed. The bFGF mRNA expression was assessed with Northern blot and protein immunoreactivity with Western blot analysis. The brief period of hypoxia caused a 2.5-fold increase in bFGF mRNA and considerable bFGF protein expression 1 day later, but prolonged hypoxia caused increase in the expression of bFGF mRNA at 2 days and no protein expression until 3 days after the start of the hypoxia. When cells were subjected to prolonged hypoxia 2 days after brief hypoxia, however, no increase in bFGF mRNA was observed, while bFGF protein was expressed continuously. We also observed that exogenously applied bFGF reduced neuronal injury produced by prolonged hypoxia. The results obtained with this model suggest that brief hypoxia induces bFGF protein and thus tolerance to subsequent lethal hypoxia. Basic FGF might play a role as a tolerance-associated factor in this process. Thus, an in vitro model is useful for assessing the response of cortical neurons to hypoxic stress and for researching new factors related to ischemic tolerance. 相似文献