全文获取类型
收费全文 | 1845篇 |
免费 | 26篇 |
专业分类
电工技术 | 22篇 |
化学工业 | 135篇 |
金属工艺 | 14篇 |
机械仪表 | 19篇 |
建筑科学 | 53篇 |
矿业工程 | 2篇 |
能源动力 | 15篇 |
轻工业 | 90篇 |
水利工程 | 4篇 |
无线电 | 199篇 |
一般工业技术 | 206篇 |
冶金工业 | 968篇 |
原子能技术 | 14篇 |
自动化技术 | 130篇 |
出版年
2021年 | 12篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 23篇 |
2013年 | 36篇 |
2012年 | 28篇 |
2011年 | 38篇 |
2010年 | 36篇 |
2009年 | 47篇 |
2008年 | 38篇 |
2007年 | 39篇 |
2006年 | 41篇 |
2005年 | 25篇 |
2004年 | 29篇 |
2003年 | 35篇 |
2002年 | 27篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 57篇 |
1998年 | 284篇 |
1997年 | 148篇 |
1996年 | 90篇 |
1995年 | 71篇 |
1994年 | 67篇 |
1993年 | 68篇 |
1992年 | 24篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 29篇 |
1988年 | 19篇 |
1987年 | 30篇 |
1986年 | 29篇 |
1985年 | 33篇 |
1984年 | 22篇 |
1983年 | 20篇 |
1982年 | 18篇 |
1981年 | 23篇 |
1980年 | 14篇 |
1979年 | 20篇 |
1978年 | 9篇 |
1977年 | 24篇 |
1976年 | 61篇 |
1975年 | 14篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1971年 | 11篇 |
排序方式: 共有1871条查询结果,搜索用时 500 毫秒
81.
Richard L. Schwartz 《Computer Languages, Systems and Structures》1978,3(2):75-94
A design for a separate compilation facility for the SIMULA 67 programming language is presented. The paper explores the problems with existing separate compilation schemes, and proposes a new scheme that allows top-down, bottom-up, or even parallel development and integration of program modules. An evaluation of the proposal and a discussion of its applicability to other languages are then given. 相似文献
82.
Berndt David J.; Schwartz Steven; Kaiser Charles F. 《Canadian Metallurgical Quarterly》1983,51(4):627
Reading grade levels were obtained for 10 depression scales (e.g., Beck Depression Inventory) using 2 empirically based readability formulae, one by R. Gunning (1952) and the other by R. F. Flesch (1949). Results suggest that most of the scales are appropriate for use with both adolescents and adult patients who have attained 9th-grade-level reading skills. The limitations of empirical estimates of readability are discussed, and it is noted that comprehension could be influenced by contextual variables such as scale format. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
83.
84.
Presents arguments crediting group therapy with the rise of eclecticism among psychologists. A 2-semester course for advanced doctoral candidates is described and its 5-yr history outlined. Items discussed include physical setup, course planning and conduct, prerequisites, observation (patient) group composition, recruitment and preparation, and therapist recruitment. Advantages of the method are presented. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
86.
In their recent review of instrumental conditioning of autonomic functions, E. S. Katkin and E. N. Murray (see 42: criticized most of the existing studies on the human level as artifactual on 1 or more grounds. The criteria they employed for rejecting these demonstrations are themselves open to criticism, however. Specifically, it is argued that (1) peripheral or cognitive mediation hypotheses are unlikely alternative explanations of the obtained results; (2) an increase in response frequency over a preconditioning operant level is not a necessary condition for demonstrating an increase in response probability with contingent reinforcement; and (3) yoked-control designs, frequently used in this research, do not automatically invalidate experiments in which they are employed. It is concluded that the strongest hypothesis to account for the existing data remains the direct instrumental strengthening of autonomic activity. (35 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
87.
B Stachel R G?tz T Herrmann F Krüger W Knoth O P?pke U Rauhut H Reincke R Schwartz E Steeg S Uhlig 《Water science and technology》2004,50(5):309-316
As a result of extreme precipitation in August 2002 major flooding occurred in the catchment area of the rivers Elbe, Vltava (Moldau) and Mulde. Pollutants from industrial sites and from municipal sewage treatment works (STW) entered the Elbe and led to a serious pollution problem in the river. PCDD/F concentrations (in pg WHO-TEQ/g dw) in SPM ranged from 7-150, in sediments from 3-140; the "safe sediment value" of 20 was exceeded in 46% of the samples. 24 eels showed a wide concentration variation for these contaminants. The WHO-PCDD/F+PCB-TEQ values lay in the range from 11-56 pg/g ww, whereby the WHO-PCB-TEQ values were several times higher than the WHO-PCDD/F-TEQ values. The maximum permitted value of 4 pg WHO-PCDD/F/g ww (EU Directive No. 2375/2001) was reached or exceeded in 54% of the individuals. A statistical analysis using data from SPM and sediment samples showed that in the Czech river section the flooding activated a contamination source in the vicinity of the Spolana works. The influence of the tributary Mulde could be clearly demonstrated. Only a major clean-up of the contaminated sites in Bitterfeld can lead to a mid to long term improvement in respect of PCDD/F and dioxin-like PCB input into the Elbe. 相似文献
88.
Mach UR Hackling AE Perachon S Ferry S Wermuth CG Schwartz JC Sokoloff P Stark H 《Chembiochem : a European journal of chemical biology》2004,5(4):508-518
Based on N-alkylated 1,2,3,4-tetrahydroisoquinoline derivatives, which are structurally related to the partial agonist BP 897, a series of novel, selective dopamine D3 receptor antagonists has been synthesised. Derivatisation included changes in the arylamide moiety and the tetrahydroisoquinoline substructure leading to compounds with markedly improved selectivities and affinities in the low nanomolar concentration range. From the 55 structures presented here, (E)-3-(4-iodophenyl)-N-(4-(1,2,3,4-tetrahydroisoquinolin-2-yl)butyl)acrylamide (51) has high affinity (Ki(hD3)=12 nM) and a 123-fold preference for the D3 receptor relative to the D2 receptor subtype. Its pharmacological profile offers the prospect of a novel radioligand as a tool for various dopamine D3-receptor-related in vitro and in vivo investigations. 相似文献
89.
Recent advances in phosphopeptide enrichment prior to mass spectrometric analysis show genuine promise for characterization of phosphoproteomes. Tandem mass spectrometry of phosphopeptide ions, using collision-activated dissociation (CAD), often produces product ions dominated by the neutral loss of phosphoric acid. Here we describe a novel method, termed Pseudo MS(n), for phosphopeptide ion dissociation in quadrupole ion trap mass spectrometers. The method induces collisional activation of product ions, those resulting from neutral loss(es) of phosphoric acid, following activation of the precursor ion. Thus, the principal neutral loss product ions are converted into a variety of structurally informative species. Since product ions from both the original precursor activation and all subsequent neutral loss product activations are simultaneously stored, the method generates a "composite" spectrum containing fragments derived from multiple precursors. In comparison to analysis by conventional MS/MS (CAD), Pseudo MS(n) shows improved phosphopeptide ion dissociation for 7 out of 10 synthetic phosphopeptides, as judged by an automated search algorithm (TurboSEQUEST). A similar overall improvement was observed upon application of Pseudo MS(n) to peptides generated by enzymatic digestion of a single phosphoprotein. Finally, when applied to a complex phosphopeptide mixture, several phosphopeptides mis-assigned by TurboSEQUEST under the conventional CAD approach were successfully identified after analysis by Pseudo MS(n). 相似文献
90.
We present a method for characterizing transceiver performance in parallel optical data links. By establishing a bidirectional link between two optically enabled chips, the conditions for a ring oscillator are made possible. We propose this technique as a means of measuring the sensitivity of transceiver latency to controlled variables such as temperature, optical output power, supply voltage, and device misalignment. This method is noninvasive and independent of the packaging, circuit topology, and optical medium used. The technique is demonstrated experimentally, and results are compared with a simulation. 相似文献