全文获取类型
收费全文 | 2008篇 |
免费 | 3篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 24篇 |
金属工艺 | 12篇 |
机械仪表 | 12篇 |
建筑科学 | 4篇 |
能源动力 | 3篇 |
轻工业 | 19篇 |
水利工程 | 3篇 |
无线电 | 24篇 |
一般工业技术 | 47篇 |
冶金工业 | 1828篇 |
原子能技术 | 11篇 |
自动化技术 | 17篇 |
出版年
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 5篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 11篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 57篇 |
1998年 | 535篇 |
1997年 | 327篇 |
1996年 | 215篇 |
1995年 | 105篇 |
1994年 | 99篇 |
1993年 | 123篇 |
1992年 | 18篇 |
1991年 | 31篇 |
1990年 | 27篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 16篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 52篇 |
1976年 | 120篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1955年 | 3篇 |
排序方式: 共有2011条查询结果,搜索用时 15 毫秒
101.
The muscle and brain creatine kinases of giant panda have been isolated and purified. The purified muscle and brain enzymes (MM and BB) are homogeneous on both the polyacrylamide gel electrophoresis in the presence and absence of SDS. Both enzymes are dimers, consisting of two identical subunits each with a molecular weight of 42,000 daltons. The characteristics of muscle and brain enzymes have been studied, respectively. The hybridized enzyme, MB, was prepared by hybridization of MM and BB. The kinetic parameters of MM, BB and MB were determined, respectively. The results from modification of SH groups show that the SH groups of panda creatine kinases are essential for their activity and among the all SH groups in the enzyme only one per subunit is essential for enzymatic activity. 相似文献
102.
J Alexander C Oseroff J Sidney P Wentworth E Keogh G Hermanson FV Chisari RT Kubo HM Grey A Sette 《Canadian Metallurgical Quarterly》1997,159(10):4753-4761
Transgenic mice expressing chimeric human (alpha1 and alpha2 HLA-A11 domains) and murine (alpha3, transmembrane, and cytoplasmic H-2Kb domains) class I molecules were derived. These mice were used as a model system to study the immunogenicity of human CTL epitopes and also to examine the aspects of Ag processing differences of mice vs man. Immunization of these mice with seven known HLA-A11-restricted CTL epitopes emulsified in IFA resulted in vigorous specific CTL responses. A larger panel of 45 A11-binding peptides was used to examine the relationship between immunogenicity in the HLA-A11/Kb transgenic mice and HLA-A11 binding capacity. Twenty-one of 28 (75%) peptides with high binding affinities (50% inhibitory concentration (IC50), 2-50 nM) and 7 of 13 (54%) intermediate binding peptides (IC50, 50-500 nM range) were immunogenic. In parallel, 19 of these peptides were used for in vitro primary immunizations of PBMC derived from HLA-A11 healthy human donors. It was found that 8 of 8 peptides that were able to elicit CTL in primary human in vitro cultures were also immunogenic in HLA-A11/Kb mice. Finally, HLA-A11/Kb transgenic mice were found to generate an A11/Kb restricted CTL response following immunization with influenza virus A/PR/8/34, suggesting that, at least to some extent, A11 epitopes are generated by transgenic mice as a result of natural in vivo processing and presentation. 相似文献
103.
104.
105.
Investigated the conditions under which the incongruity effect was obtained in the free recall of generated targets in 2 experiments using 80 undergraduates. In Exp I, Ss were free to generate a response of their own choosing, and the incongruity effect was obtained; in Exp II, the generated response was predetermined, and the incongruity effect disappeared. It is concluded that the incongruity effect is an artifact of idiosyncratic item selection effects. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
107.
108.
D. Q. Hwang R. D. Horton S. Howard R. W. Evans S. J. Brockington 《Journal of Fusion Energy》2007,26(1-2):81-84
Several new experiments have been conducted on the UC Davis repetitive-pulsed spheromak-like compact toroid (SCT) accelerator
(CTIX). (1) SCT density and kinetic energy density has been increased by gas puffing in the acceleration section. With gas
puffing, SCT electrical to kinetic energy conversion efficiency has been increased to >20%. (2) SCT interaction with targets
has been recorded with a fast visible imaging system, combined with target-region helium gas puffing for increased brightness.
Images of both coherent waves and turbulent flow patterns were observed in the target region after the interaction. (3) A
laser deflection density diagnostic has been improved to obtain better reliability and resolution. Operated with high-density
gas-puffed SCTs, the second-generation diagnostic has successfully measured axial as well as radial deflection. The measured
line averaged densities are in good agreement with a conventional quadrature laser interferometer. 相似文献
109.
PA Winchester HM Lee NM Khilnani Y Wang DW Trost HL Bush TA Sos 《Canadian Metallurgical Quarterly》1998,9(6):891-9; discussion 900
PURPOSE: To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA). MATERIALS AND METHODS: Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found. RESULTS: Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively. CONCLUSION: Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity. 相似文献
110.
HM Trist SG Tyack MA Johnson CT Prideaux M Sheppard 《Canadian Metallurgical Quarterly》1996,40(1):130-139
Restriction enzyme linkage maps were produced for the genomic short region of the virulent infectious laryngotracheitis virus (CSW-1 strain). After comparison with the equivalent restriction enzyme linkage maps for the infectious laryngotracheitis virus SA-2 strain (a vaccine strain), it was determined that the maps for the short regions of the two strains were identical, apart from a single section in each of the inverted terminal repeats. Each inverted terminal repeat of the SA-2 strain was discovered to contain 467 base pairs more DNA than the CSW-1 strain's inverted terminal repeats. This extra DNA was more precisely mapped entirely within the EcoRI fragments D and d of SA-2, which were found to form part of the SmaI fragments U and P of SA-2 and Q and b of SA-2 and to contain one SmaI restriction enzyme site. 相似文献