全文获取类型
收费全文 | 135篇 |
免费 | 2篇 |
专业分类
化学工业 | 11篇 |
建筑科学 | 4篇 |
能源动力 | 2篇 |
轻工业 | 22篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 8篇 |
一般工业技术 | 14篇 |
冶金工业 | 57篇 |
自动化技术 | 17篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 18篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1965年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有137条查询结果,搜索用时 406 毫秒
41.
Kenneth J. Stephan Lynne Jianxiong Tom Peter Joe Ireland 《Computer Standards & Interfaces》2006,28(6):635-649
The need for policies to control calls is justified by the changing face of communications. It is argued that call control requires distinctive capabilities in a policy system. A specialised policy language called APPEL (ACCENT Project Policy Environment/Language) has therefore been developed for this purpose. However, the policy language is cleanly separated into a core plus specialisations for various application domains. The paper describes both the foundation and the call control ontologies. Sample policy examples are provided to illustrate use for call control. The paper also presents the policy system architecture in which the policy language is interpreted. The components of the policy system are described, particularly the policy server and the policy wizard. 相似文献
42.
The structured programming literature provides methods and a wealth of heuristic knowledge for guiding the construction of
provably correct imperative programs. We investigate these methods and heuristics as a basis for mechanizing program synthesis.
Our approach combines proof planning with conventional partial order planning. Proof planning is an automated theorem proving technique which uses high-level proof plans to guide the search for proofs. Proof plans are structured in terms of proof methods, which encapsulate heuristics for guiding proof search. We demonstrate that proof planning provides a local perspective on
the synthesis task. In particular, we show that proof methods can be extended to represent heuristics for guiding program
construction. Partial order planning complements proof planning by providing a global perspective on the synthesis task. This
means that it allows us to reason about the order in which program fragments are composed. Our hybrid approach has been implemented
in a semi-automatic system called Bertha. Bertha supports partial correctness and has been tested on a wide range of non-trivial programming examples. 相似文献
43.
This review chronicles the key concepts, studies, advancements and terms that have led to our current understanding of turnover of dominant follicles (growth and atresia) during the bovine estrous cycle. The "two-wave" concept of follicular development was first proposed in 1960, but remained controversial for the next 28 yr. The concept of the "dominant" follicle was adapted to cattle in 1987. By 1988, ultrasound analysis of individual follicles had demonstrated that heifers usually had two or three distinct waves of turnover of dominant follicles during an estrous cycle. From 1992 to 1993, it was established that a transient rise in serum concentrations of FSH initiated each follicular wave, and a decreased episodic secretion of LH was associated with loss of dominance and the end of a nonovulatory follicular wave. In the past decade, numerous intrafollicular growth factors, such as inhibins, activins, and insulin-like growth factors and their binding proteins, have been identified in follicular fluid of individual bovine follicles. In addition, in vitro studies demonstrate that these growth factors could have endocrine, autocrine, or paracrine actions that modify gonadotropin-stimulated follicular growth and differentiation. However, the precise role of intrafollicular growth factors in turnover of dominant follicles has not been defined. We concluded that two or three FSH-stimulated waves of follicular growth usually occur during the bovine estrous cycle, and each follicular wave culminates in development of a single nonovulatory or ovulatory dominant follicle. 相似文献
44.
The boundary element method is well adjusted to the numerical resolution of thermal diffusion problems existing in complex volumes such as teeth. This technique is used to determine the temperatures in the bulk and on the surface of a tooth illuminated by a CO2 laser beam. The parameters taken into account in calculations include power absorbed by the tooth, laser irradiation time, and diameter of the beam on the tooth. In each case, a very fast and short heating period is observed on the tooth surface; then, the temperature decreases slowly. Inside the tooth, temperature variations are small or nonexistent. Temperature increases due to a laser beam remain concentrated at the impact region. Results are in reasonable agreement with experimental results. 相似文献
45.
10年前把尼龙挤到市场份额的第四位后,聚丙烯持续进行着有条不紊的拓展。在回顾聚丙烯成功的潜在原因后,用图表对市场份额最大的国家和产品进行说明。 相似文献
46.
你可能使用一个ADT7461型单通道温度监控器.一个ADG708型低压低漏电CMOS 8对1多路复用器和三只标准2N3906型PNP晶体管来测量三个独立的远程高温区的温度(图1)。多路复用器的电阻RON与三只晶体管有关;通道匹配和电阻RON的平坦度通常都会引起不同的温度偏移。这一系统使用的ADT7461型温度监控器能自动抵消与外部温度传感器串联的电阻.从而可用作多通道温度监控器。电阻自动抵消后.RON平坦度和通道闻的变化就不会有什么影响。 相似文献
47.
Simons Robert F.; MacMillan Frank W.; Ireland Frederick B. 《Canadian Metallurgical Quarterly》1982,91(6):414
Investigated whether evidence of RT crossover could be obtained in nonpsychotic, schizotypic Ss. Two groups of male undergraduates (N?=?33) were defined as schizotypic based on their high scores on either the Perceptual Aberration or Physical Anhedonia Scales. Schizotypic Ss were compared to 18 male normal controls using the "embedded set" procedure of A. Bellissimo and R. A. Steffy (see record 1973-09283-001). This procedure has frequently been used to demonstrate crossover among process schizophrenics. Both groups of schizotypic Ss showed evidence of RT crossover relative to control Ss, with the strongest pattern produced by the perceptual-aberration Ss. Results support the utility of this procedure in the study of psychological vulnerability and provide further evidence that Ss identified by high scores on these psychometric instruments may represent groups of psychosis-prone young adults. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
Colgrave ML Kotze AC Ireland DC Wang CK Craik DJ 《Chembiochem : a European journal of chemical biology》2008,9(12):1939-1945
The cyclotides are a family of backbone-cyclised cystine-knot-containing peptides from plants that possess anthelmintic activity against Haemonchus contortus and Trichostrongylus colubriformis, two important gastrointestinal nematode parasites of sheep. In the current study, we investigated the in vitro effects of newly discovered natural cyclotides on the viability of larval and adult life stages of these pests. The natural variants cycloviolacin O2, cycloviolacin O3, cycloviolacin O8, cycloviolacin O13, cycloviolacin O14, cycloviolacin O15, and cycloviolacin O16 extracted from Viola odorata showed up to 18-fold greater potency than the prototypic cyclotide kalata B1 in nematode larval development assays. Cycloviolacin O2 and cycloviolacin O14 were significantly more potent than kalata B1 in adult H. contortus motility assays. The lysine and glutamic acid residues of cycloviolacin O2, the most potent anthelmintic cyclotide, were chemically modified to investigate the role of these charged residues in modulating the biological activity. The single glutamic acid residue, which is conserved across all known cyclotides, was shown to be essential for activity, with a sixfold decrease in potency of cycloviolacin O2 following methylation. The three lysine residues present in cycloviolacin O2 were acetylated to effectively mask the positive charge, resulting in a 18-fold decrease in anthelmintic activity. The relative anthelmintic activities of the natural variants assayed against nematode larvae correlated with the number of charged residues present in their sequence. 相似文献
49.
The key to a successful proof often lies within the analysis of failed proof attempts. Motivated by this observation we have
developed and evaluated an interface to an inductive theorem prover which supports a collaborative style of failure analysis.
Our work builds upon an automatic proof patching mechanism and extends the capabilities of an existing theorem proving interface.
Our approach is multi-disciplinary, we draw upon work from both the automated theorem proving and human computer interaction
communities.
Received November 1998 / Accepted in revised form June 1999 相似文献
50.
The objective of this study was to evaluate the effects of recombinant bovine growth hormone-releasing factor (rGRF) or recombinant bovine somatotropin (rbST) on growth and function of the first-wave dominant follicle and corpus luteum. Primiparous Holstein cows (117 d postpartum) were infused with 12 mg/d of rGRF (n = 10) or 29 mg/d of rbST (n = 10) for 63 d, and non-infused cows (n = 10) were controls. At slaughter on d 5 of an estrous cycle, blood and ovaries were collected and data from cows with a corpus luteum were analyzed (control, n = 8; rGRF, n = 5; rbST, n = 6). Treatment with rGRF or rbST increased somatotropin (ST) and IGF-I in serum similarly compared with controls. In contrast, rbST-treated cows had higher concentrations of ST in follicular fluid (FF) compared with rGRF-treated and control cows. In addition, rbST, but not rGRF, increased the number and decreased the size of estrogen-active follicles (EA; estradiol > progesterone concentrations in FF), increased the abundance of IGF binding proteins-2, -3, and -4 in FF from EA follicles, and increased the number but decreased the size of corpora lutea and decreased concentration of progesterone in serum compared with controls. Based on these results, we concluded that long-term infusion of rbST alters growth and function of the first-wave dominant follicle and the corpus luteum in cattle. 相似文献