全文获取类型
收费全文 | 1816篇 |
免费 | 26篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 120篇 |
金属工艺 | 16篇 |
机械仪表 | 14篇 |
建筑科学 | 35篇 |
矿业工程 | 3篇 |
能源动力 | 25篇 |
轻工业 | 89篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 84篇 |
一般工业技术 | 130篇 |
冶金工业 | 1188篇 |
原子能技术 | 13篇 |
自动化技术 | 103篇 |
出版年
2022年 | 5篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 17篇 |
2016年 | 13篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 20篇 |
2008年 | 38篇 |
2007年 | 27篇 |
2006年 | 19篇 |
2005年 | 39篇 |
2004年 | 27篇 |
2003年 | 17篇 |
2002年 | 19篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1999年 | 46篇 |
1998年 | 335篇 |
1997年 | 203篇 |
1996年 | 142篇 |
1995年 | 85篇 |
1994年 | 64篇 |
1993年 | 74篇 |
1992年 | 13篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 31篇 |
1987年 | 23篇 |
1986年 | 30篇 |
1985年 | 29篇 |
1984年 | 19篇 |
1983年 | 9篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 14篇 |
1977年 | 36篇 |
1976年 | 107篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1970年 | 6篇 |
1967年 | 4篇 |
排序方式: 共有1844条查询结果,搜索用时 15 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.
GN Mozhokina GB Sokolova OV Makarova LP Mikha?lova 《Canadian Metallurgical Quarterly》1996,41(7-8):31-33
The effect of lomefloxacin was studied on mice with experimental infection due to Mycobacterium tuberculosis. The antibiotic was administered in doses of 100 and 200 mg/kg. It was shown that the use of lomefloxacin for a month provided a lower death rate of the animals with progressing acute generalized tuberculosis, a lower level of the lesions in the internal organs and a lower number of the Mycobacterium isolates from them. The efficacy of the treatment depended on the drug dose. When lomefloxacin was used in a dose of 200 mg/kg, the survival rate was much higher and the number of the epithelial unicellular granulomas in the tissue of the lung and spleen was markedly decreased while with the lower dose the indices did not differ from those in the control. 相似文献
4.
5.
Cypriano G da Trindade Neto Ana LP Fernandes Ana IB Santos Waldenice A Morais Marcos VM Navarro Tereza NC Dantas Mrcia R Pereira Jos LC Fonseca 《Polymer International》2005,54(4):659-666
Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry 相似文献
6.
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
7.
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
8.
9.
10.