全文获取类型
收费全文 | 3858篇 |
免费 | 28篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 22篇 |
综合类 | 1篇 |
化学工业 | 304篇 |
金属工艺 | 17篇 |
机械仪表 | 55篇 |
建筑科学 | 96篇 |
矿业工程 | 13篇 |
能源动力 | 54篇 |
轻工业 | 186篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 245篇 |
一般工业技术 | 295篇 |
冶金工业 | 2316篇 |
原子能技术 | 19篇 |
自动化技术 | 255篇 |
出版年
2022年 | 17篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 18篇 |
2016年 | 17篇 |
2015年 | 22篇 |
2014年 | 20篇 |
2013年 | 82篇 |
2012年 | 50篇 |
2011年 | 52篇 |
2010年 | 51篇 |
2009年 | 40篇 |
2008年 | 55篇 |
2007年 | 64篇 |
2006年 | 63篇 |
2005年 | 59篇 |
2004年 | 40篇 |
2003年 | 52篇 |
2002年 | 39篇 |
2001年 | 49篇 |
2000年 | 50篇 |
1999年 | 102篇 |
1998年 | 687篇 |
1997年 | 389篇 |
1996年 | 281篇 |
1995年 | 150篇 |
1994年 | 140篇 |
1993年 | 156篇 |
1992年 | 35篇 |
1991年 | 57篇 |
1990年 | 50篇 |
1989年 | 53篇 |
1988年 | 84篇 |
1987年 | 57篇 |
1986年 | 50篇 |
1985年 | 57篇 |
1984年 | 26篇 |
1983年 | 35篇 |
1982年 | 41篇 |
1981年 | 50篇 |
1980年 | 31篇 |
1979年 | 23篇 |
1978年 | 15篇 |
1977年 | 86篇 |
1976年 | 155篇 |
1973年 | 21篇 |
1972年 | 14篇 |
1966年 | 13篇 |
排序方式: 共有3888条查询结果,搜索用时 125 毫秒
81.
82.
GS Bhudhikanok J Lim R Marcus A Harkins RB Moss LK Bachrach 《Canadian Metallurgical Quarterly》1996,97(1):103-111
The responses to heat shock in Tritrichomonas mobilensis, a squirrel monkey parasite and Tritrichomonas augusta, an amphibian trichomonad, were evaluated by means of metabolic labeling with [35S]methionine. Electrophoretically separated trichomonad proteins synthesized at different temperatures were visualized by autoradiography and the label incorporation quantitated by a trichloroacetic acid precipitation procedure. A considerable difference in thermotolerance between the two species was found as the protein synthesis reached a maximum at 41 C in T. mobilensis and 37 C in T. augusta. The latter tolerated temperature increases 13 C above normal cultivation temperatures as compared to only 4 C thermotolerance range above normal in T. mobilensis. Major heat shock proteins (Hsps) were expressed in both T. mobilensis (with apparent Mr 94, 72, and 58 kDa) and T. augusta (Mr 94, 70, and 56 kDa) as revealed by autoradiography. Western blot analysis with polyclonal antibody against DnaK of Escherichia coli showed the presence of antigenic Hsp70 homologs in both trichomonads. Similarly, a polyclonal antibody against Hsp60 with broad interspecies cross-reactivity detected Hsp60 homologs in both T. mobilensis and T. augusta. The anti-DnaK antibody cross-reacted with a T. mobilensis protein localized in Golgi apparatus as demonstrated by immunoelectron microscopy. Immunocytochemistry on trichomonad frozen sections revealed the presence of the Hsp60 homolog in light-microscopic granules corresponding to hydrogenosomes. 相似文献
83.
84.
85.
The effects of nitric oxide (NO) annealing on conventional thermal oxides are reported in this letter. The oxide thickness increase, resulting from NO annealing, is found to be only a few angstroms (<0.5 nm) and independent on the initial oxide thickness. Furthermore, both the electrical and physical characteristics are improved. This technique is expected to achieve sub-5 nm high quality ultrathin dielectric films for the applications in EEPROM's and ULSI 相似文献
86.
RJ O''Hara J Greenman PJ Drew AW McDonald GS Duthie PW Lee JR Monson 《Canadian Metallurgical Quarterly》1998,41(4):460-463
OBJECTIVE: Spontaneous spinal epidural hematoma (SSEH) is an idiopathic accumulation of blood in the vertebral epidural space without identifiable predisposing factors. First reported in 1869, the clinical outcome in children younger than 18 years old has not been clearly delineated. DESIGN: A comprehensive review of the English language literature revealed 26 patients younger than 18 years old with reported clinical outcomes. The 27th case is presented. RESULTS: Complete neurologic recovery occurred in 14 of 27 (52%) patients, partial recovery in 12 of 27 (44%) patients, and death in 1 of 27 (4%) patients. CONCLUSION: There is an overall good prognosis for neurologic recovery in children who experience SSEH. 相似文献
87.
TS Bocanegra AL Weaver EA Tindall DH Sikes JA Ball CB Wallemark GS Geis JG Fort 《Canadian Metallurgical Quarterly》1998,25(8):1602-1611
88.
D Morgan L Turnpenny J Goodship W Dai K Majumder L Matthews A Gardner G Schuster L Vien W Harrison FF Elder M Penman-Splitt P Overbeek T Strachan 《Canadian Metallurgical Quarterly》1998,20(2):149-156
A DNA fragment containing the recA gene of Gluconobacter oxydans was isolated and further characterized for its nucleotide sequence and ability to functionally complement various recA mutations. When expressed in an Escherichia coli recA host, the G. oxydans recA protein could efficiently function in homologous recombination and DNA damage repair. The recA gene's nucleotide sequence analysis revealed a protein of 344 amino acids with a molecular mass of 38 kDa. We observed an E. coli-like LexA repressor-binding site in the G. oxydans recA gene promoter region, suggesting that a LexA-like mediated response system may exist in G. oxydans. The expression of G. oxydans recA in E. coli RR1, a recA+ strain, surprisingly caused a remarkable reduction of the host wild-type recA gene function, whereas the expression of both Serratia marcescens recA and Pseudomonas aeruginosa recA gene caused only a slight inhibitory effect on function of the host wild-type recA gene product. Compared with the E. coli RecA protein, the identity of the amino acid sequence of G. oxydans RecA protein is much lower than those RecA proteins of both S. marcescens and Pseudomonas aeruginosa. This result suggests that the expression of another wild-type RecA could interfere with host wild-type recA gene's function, and the extent of such an interference is possibly correlated to the identity of the amino acid sequence between the two classes of RecA protein. 相似文献
89.
JG Gribben GJ Freeman VA Boussiotis P Rennert CL Jellis E Greenfield M Barber VA Restivo X Ke GS Gray 《Canadian Metallurgical Quarterly》1995,92(3):811-815
The regulation of T cell-mediated immune responses requires a balance between amplification and generation of effector function and subsequent selective termination by clonal deletion. Although apoptosis of previously activated T cells can be induced by signaling of the tumor necrosis factor receptor family, these molecules do not appear to regulate T-cell clonal deletion in an antigen-specific fashion. We demonstrate that cross-linking of the inducible T-cell surface molecule CTLA4 can mediate apoptosis of previously activated human T lymphocytes. This function appears to be antigen-restricted, since a concomitant signal T-cell receptor signal is required. Regulation of this pathway may provide a novel therapeutic strategy to delete antigen-specific activated T cells. 相似文献
90.
In this paper we explore the idea of aggression as a defence against threats to the psychological self. This aspect of the self allows reflection about people in psychological terms and develops, in the first three years of life, through appreciation of mental states in the other. When the object is unpredictable or hostile, recognition of this is painful to the child, and his reflective function will not be adequately established. The defences of aggression or avoidance will be invoked very frequently. In time, aggression may become an organising influence in the construction of the self; pathological destructiveness then takes the place of emotional relatedness and concern for the other. Psychoanalytic treatment no longer works primarily by addressing conflict. Instead, particularly through interpretations of transference and countertransference, the analyst recreates an intersubjective process which enhances the patient's reflective self, this time in the safety of a benign relationship. 相似文献