全文获取类型
收费全文 | 1483篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 117篇 |
金属工艺 | 16篇 |
机械仪表 | 15篇 |
建筑科学 | 35篇 |
矿业工程 | 3篇 |
能源动力 | 25篇 |
轻工业 | 88篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 85篇 |
一般工业技术 | 126篇 |
冶金工业 | 861篇 |
原子能技术 | 13篇 |
自动化技术 | 102篇 |
出版年
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 16篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 29篇 |
2010年 | 11篇 |
2009年 | 20篇 |
2008年 | 38篇 |
2007年 | 27篇 |
2006年 | 19篇 |
2005年 | 38篇 |
2004年 | 26篇 |
2003年 | 17篇 |
2002年 | 21篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1999年 | 43篇 |
1998年 | 250篇 |
1997年 | 143篇 |
1996年 | 121篇 |
1995年 | 68篇 |
1994年 | 58篇 |
1993年 | 62篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 28篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 21篇 |
1984年 | 19篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 23篇 |
1976年 | 34篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1970年 | 6篇 |
1968年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有1510条查询结果,搜索用时 140 毫秒
1.
Fertuck Eric A.; Bucci Wilma; Blatt Sidney J.; Ford Richard Q. 《Canadian Metallurgical Quarterly》2004,41(1):13
This study examined the relation between changes in clinical functioning and changes in verbal expression in 81 seriously disturbed and treatment-resistant young adults seen in a comprehensive, psychoanalytically oriented inpatient treatment. Clinical functioning was evaluated with a battery of clinical and social measures. Verbal representations were assessed using computer-assisted scoring of Thematic Apperception Test responses. Changes in the frequency of verbal content and style in the narratives of these patients covaried with changes in clinical functioning. Significantly different covariations of verbal and clinical change, particularly differences in covariates of referential activity, were found for patients with anaclitic versus introjective personality configurations. The implications of these findings for understanding and treating severe psychopathology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Antisense oligonucleotide inhibition of hepatitis C virus gene expression in transformed hepatocytes
R Hanecak V Brown-Driver MC Fox RF Azad S Furusako C Nozaki C Ford H Sasmor KP Anderson 《Canadian Metallurgical Quarterly》1996,70(8):5203-5212
Genetic and biochemical studies have provided convincing evidence that the 5' noncoding region (5' NCR) of hepatitis C virus (HCV) is highly conserved among viral isolates worldwide and that translation of HCV is directed by an internal ribosome entry site (IRES) located within the 5' NCR. We have investigated inhibition of HCV gene expression using antisense oligonucleotides complementary to the 5' NCR, translation initiation codon, and core protein coding sequences. Oligonucleotides were evaluated for activity after treatment of a human hepatocyte cell line expressing the HCV 5' NCR, core protein coding sequences, and the majority of the envelope gene (E1). More than 50 oligonucleotides were evaluated for inhibition of HCV RNA and protein expression. Two oligonucleotides, ISIS 6095, targeted to a stem-loop structure within the 5' NCR known to be important for IRES function, and ISIS 6547, targeted to sequences spanning the AUG used for initiation of HCV polyprotein translation, were found to be the most effective at inhibiting HCV gene expression. ISIS 6095 and 6547 caused concentration-dependent reductions in HCV RNA and protein levels, with 50% inhibitory concentrations of 0.1 to 0.2 microM. Reduction of RNA levels, and subsequently protein levels, by these phosphorothioate oligonucleotides was consistent with RNase H cleavage of RNA at the site of oligonucleotide hybridization. Chemically modified HCV antisense phosphodiester oligonucleotides were designed and evaluated for inhibition of core protein expression to identify oligonucleotides and HCV target sequences that do not require RNase H activity to inhibit expression. A uniformly modified 2'-methoxyethoxy phosphodiester antisense oligonucleotide complementary to the initiator AUG reduced HCV core protein levels as effectively as phosphorothioate oligonucleotide ISIS 6095 but without reducing HCV RNA levels. Results of our studies show that HCV gene expression is reduced by antisense oligonucleotides and demonstrate that it is feasible to design antisense oligonucleotide inhibitors of translation that do not require RNase H activation. The data demonstrate that chemically modified antisense oligonucleotides can be used as tools to identify important regulatory sequences and/or structures important for efficient translation of HCV. 相似文献
3.
4.
5.
Utilizing data from the Riggs-Yale Project, 45 male and 45 female 18-29-year-old treatment-resistant inpatients undergoing intensive psychoanalytically oriented treatment were studied. Twenty-seven mixed-type anaclitic-introjective inpatients were compared with 29 "pure" anaclitic and 34 "pure" introjective inpatients. At intake, mixed-type inpatients were more clinically impaired (i.e., were more symptomatic, cognitively impaired, and thought disordered) and more vulnerable (i.e., less accurate object representations and more frequently used maladaptive defense mechanisms) in comparison with clearly defined anaclitic and introjective patients. Mixed-type patients, however, improved significantly more in the course of psychoanalytically oriented treatment, in terms of clinical functioning (i.e., symptoms, cognitive functioning) and psychological vulnerability (i.e., utilization of more adaptive defense mechanisms). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Multichannel security protocols transmit messages over multiple communication channels, taking into account each channel's security properties. Our first intentional use of these protocols goes back to a 1999 article that proposed physical contact for imprinting as opposed to the wireless channel used in subsequent operations. Only later did we understand three key points. First, explicit use of multiple channels in the same protocol can offer significant advantages for both security and usability. Second, explicitly stating the properties of the channel on which each protocol message is transmitted is useful for understanding one's own protocol in greater depth and therefore for addressing subtle vulnerabilities early on. Third, multichannel protocols existed long before we recognized them as such - think of the courier handcuffed to the briefcase carrying the code book that will later protect postal or telegraphic traffic. The paper presents a security protocol that exploit additional transmissions over lower-capacity channels, typically found in ubicomp environments, that offer a different combination of security properties. 相似文献
7.
Two patients are presented where internal mammary artery grafting was performed for the relief of symptomatic coronary artery disease. At follow-up the internal mammary artery was occluded and a communication between the internal mammary vein and the native coronary artery was demonstrated. These patients were characterised by the early recurrence of angina or the appearance of a continuous murmur. Both patients were treated by re-operation with ligation of the arterio-venous fistula and saphenous vein grafting. 相似文献
8.
LH Ford 《Canadian Metallurgical Quarterly》1987,35(10):2955-2960
9.
From the rhizomes of Polygonatum alte-lobatum, two new homologous series of 1,4-benzoquinones, polygonaquinones A and B, a novel homoisoflavanone, a new gentrogenin glycoside and 13 known compounds were isolated and characterized. The structures of the new compounds were determined as two homologous series of three 2,5-dihydroxy-3-methyl-6-alkyl-1,4-benzoquinones and three 2-hydroxy-3-methyl-6-alkyl-1,4-benzoquinones, with chain lengths C21 to C23, and 4',5,7-trihydroxy-6,8-dimethylhomoisoflavanone and gentrogenin 3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)] -beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside. 相似文献
10.