全文获取类型
收费全文 | 500361篇 |
免费 | 13276篇 |
国内免费 | 6345篇 |
专业分类
电工技术 | 12253篇 |
技术理论 | 2篇 |
综合类 | 8314篇 |
化学工业 | 69417篇 |
金属工艺 | 21477篇 |
机械仪表 | 17574篇 |
建筑科学 | 17018篇 |
矿业工程 | 3068篇 |
能源动力 | 13131篇 |
轻工业 | 43537篇 |
水利工程 | 5657篇 |
石油天然气 | 6599篇 |
武器工业 | 695篇 |
无线电 | 65537篇 |
一般工业技术 | 88406篇 |
冶金工业 | 76141篇 |
原子能技术 | 5672篇 |
自动化技术 | 65484篇 |
出版年
2023年 | 2074篇 |
2022年 | 3964篇 |
2021年 | 5925篇 |
2020年 | 4236篇 |
2019年 | 4280篇 |
2018年 | 19450篇 |
2017年 | 18851篇 |
2016年 | 15589篇 |
2015年 | 6789篇 |
2014年 | 9383篇 |
2013年 | 21231篇 |
2012年 | 17422篇 |
2011年 | 27806篇 |
2010年 | 23178篇 |
2009年 | 21757篇 |
2008年 | 23513篇 |
2007年 | 24251篇 |
2006年 | 16054篇 |
2005年 | 15132篇 |
2004年 | 13344篇 |
2003年 | 12644篇 |
2002年 | 11386篇 |
2001年 | 11293篇 |
2000年 | 10393篇 |
1999年 | 11187篇 |
1998年 | 26477篇 |
1997年 | 18265篇 |
1996年 | 14064篇 |
1995年 | 10370篇 |
1994年 | 8957篇 |
1993年 | 8628篇 |
1992年 | 5886篇 |
1991年 | 5544篇 |
1990年 | 5116篇 |
1989年 | 4752篇 |
1988年 | 4474篇 |
1987年 | 3494篇 |
1986年 | 3371篇 |
1985年 | 4051篇 |
1984年 | 3567篇 |
1983年 | 3220篇 |
1982年 | 2993篇 |
1981年 | 3003篇 |
1980年 | 2725篇 |
1979年 | 2486篇 |
1978年 | 2253篇 |
1977年 | 2674篇 |
1976年 | 3649篇 |
1975年 | 1852篇 |
1973年 | 1786篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
81.
C Wittekind 《Canadian Metallurgical Quarterly》1996,121(6):435-441
A subpopulation of rabbit polyclonal anti-idiotypic antibody (anti-Id) was previously produced to a murine monoclonal antibody (mAb) (M1875) specific for the bluetongue virus core protein VP7. In this report, mimicry of VP7 by this anti-Id (designated RAb2-A) was functionally analyzed through immunization of Balb/c mice with RAb2-A or purified VP7. Animals immunized with RAb2-A were able to produce an M1875-like Ab3 antibody response with idiotype and epitope specificity resembling that of M1875 without subsequent exposure to the nominal antigen. This conclusion was supported by experiments showing that the RAb2-A-induced Ab3 antibodies (i) reacted specifically with the immunizing anti-Id; (ii) were capable of binding VP7; (iii) inhibited M1875 from binding to VP7; and (iv) inhibited M1875 from binding to RAb2-A. Similarly, mice immunized with purified VP7 also produced antibodies that exhibited characteristics such as idiotype and epitope specificity in common with M1875. No antibody response to VP7 was detected in control groups of mice immunized with either normal rabbit IgG or BHK-21 cell components. Therefore, it can be concluded that rabbit anti-Id RAb-2-A mimics an M1875-defined VP7 epitope sufficiently to function as a surrogate antigen for inducing an anti-bluetongue virus response. 相似文献
82.
W. Lim C. K. Wang 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1996,370(2-3):568-572
The one-dimensional (1D) position-sensitive superheated-liquid-droplet dosimeter (SLDD) has been fabricated and tested in the laboratory. The 1D SLDD is fabricated from a 9.525-mm OD, 6.35-mm ID, 20-cm long, Plexiglas-walled tube filled with a mixture of superheated-liquid Freon droplets and host medium glycerol. Washer-shaped piezoelectric acoustic transducers are positioned at both ends of the tube; they determine the number and positions of the acoustic events when the superheated-liquid droplets evaporate upon neutron irradiation. The SLDD is irradiated with the 137Cs and 60Co γ-sources, as well as 252Cf neutron source to test for its radiation response and spatial resolution. The SLDD based on the Freon-134a superheated-liquid droplets operating at 20°C and 1 atm is found to be ideal for measuring absorbed neutron dose. This study also proves that the positions of the radiation-induced nucleation acoustic events can be linearly determined from the differences in the transmission times received by the acoustic transducers on the 1D SLDD. The spatial resolution of the neutron depth-dose is 1 mm due the finite response time (1 μs) of the piezoelectric acoustic transducers. 相似文献
83.
84.
The Frizzled genes encode receptors for WNTs, secreted glycoproteins implicated in development as well as in carcinogenesis. In this paper, we report molecular cloning of Hfz6, the human homologue of Mfz6. Nucleotide sequence analysis showed that the Hfz6 gene encodes the 706 amino-acid protein with seven transmembrane domains, a cystein-rich domain in the N-terminal extracellular region, two N-linked glycosylation sites, and two cystein residues in the second and third extracellular loops. Hfz6 mRNA 4.4-kb in size was detected in various normal adult and fetal tissues, and a larger amount of Hfz6 mRNA was detected in both fetal lung and fetal kidney. The Hfz6 gene has been mapped to human chromosome 8q22.3-q23.1. In conclusion, we have cloned Hfz6, which encodes a seven-transmembrane receptor with the cystein-rich domain in the N-terminal extracellular region, but without the Ser/Thr-X-Val motif in the C-terminus. 相似文献
85.
In this study, the effect and side-effect of epidural injection with lappaconitine compound for post-operative analgesia was observed. One hundred and twenty patients were randomly divided into 4 groups. Lappaconitine compound (LB) consisted of 12 mg of lappaconitine and 22.5 mg of bupivacaine, was given to group A (the group of observation), and lappaconitine 12 mg, bupivacaine 22.5 mg and morphine 2 mg to group B, C and D respectively for control. All were given by epidural injection with single blind method during post-operative pain of incision operation. Result showed that the initiating of analgesia was quicker in group A and C than that in group B and D, and the efficacy was group D > A > C > B. There was significant difference between group A and B in the above two parameters, P < 0.01 and P < 0.05. The analgisia maintenence time of single injection was D > A > B > C, that of group D was significantly longer than that of group A (P < 0.01). It indicated that the epidural injection with LB was more rapid and potent than that with lappaconitine alone in post-operative analgesia, and the former had no side-effect, it was safer than morphine. 相似文献
86.
87.
88.
89.
90.