全文获取类型
收费全文 | 104182篇 |
免费 | 21142篇 |
国内免费 | 2056篇 |
专业分类
电工技术 | 4004篇 |
技术理论 | 1篇 |
综合类 | 2268篇 |
化学工业 | 37920篇 |
金属工艺 | 2417篇 |
机械仪表 | 2857篇 |
建筑科学 | 3462篇 |
矿业工程 | 403篇 |
能源动力 | 2461篇 |
轻工业 | 23010篇 |
水利工程 | 758篇 |
石油天然气 | 2130篇 |
武器工业 | 231篇 |
无线电 | 12002篇 |
一般工业技术 | 19835篇 |
冶金工业 | 1752篇 |
原子能技术 | 537篇 |
自动化技术 | 11332篇 |
出版年
2024年 | 282篇 |
2023年 | 953篇 |
2022年 | 3376篇 |
2021年 | 3851篇 |
2020年 | 4318篇 |
2019年 | 6855篇 |
2018年 | 6180篇 |
2017年 | 6930篇 |
2016年 | 6841篇 |
2015年 | 6828篇 |
2014年 | 7305篇 |
2013年 | 7968篇 |
2012年 | 7384篇 |
2011年 | 7454篇 |
2010年 | 5740篇 |
2009年 | 5396篇 |
2008年 | 5206篇 |
2007年 | 5347篇 |
2006年 | 4973篇 |
2005年 | 4057篇 |
2004年 | 3541篇 |
2003年 | 3150篇 |
2002年 | 2906篇 |
2001年 | 2343篇 |
2000年 | 2060篇 |
1999年 | 1485篇 |
1998年 | 579篇 |
1997年 | 519篇 |
1996年 | 554篇 |
1995年 | 515篇 |
1994年 | 474篇 |
1993年 | 343篇 |
1992年 | 306篇 |
1991年 | 233篇 |
1990年 | 197篇 |
1989年 | 169篇 |
1988年 | 126篇 |
1987年 | 97篇 |
1986年 | 109篇 |
1985年 | 79篇 |
1984年 | 72篇 |
1983年 | 37篇 |
1982年 | 40篇 |
1981年 | 33篇 |
1980年 | 59篇 |
1979年 | 37篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
101.
102.
J Strother Moore 《Formal Aspects of Computing》1994,6(1):60-91
We present a formal model of asynchronous communication between two digital hardware devices. The model takes the form of a function in the Boyer-Moore logic. The function transforms the signal stream generated by one processor into that consumed by an independently clocked processor, given the phases and rates of the two clocks and the communications delay. The model can be used quantitatively to derive concrete performance bounds on communications at ISO protocol level 1 (physical level). We use the model to show that an 18-bit/cell biphase mark protocol reliably sends messages of arbitrary length between two processors provided the ratio of the clock rates is within 5% of unity. 相似文献
103.
104.
105.
106.
乳腺癌中着丝粒蛋白CenpG的差异表达 总被引:4,自引:0,他引:4
用间接免疫荧光(IIF)验证了着丝粒蛋白CenpG的一种抗血清;通过对31例乳腺癌组织块及每一例病人的癌旁正常(非癌性)组织块蛋白提取物进行免疫印迹(Western blot)分析,发现多数情况下(71%)癌组织中着丝粒蛋白CenpG(95kD)过表达;在两例乳腺癌组织中还发现了一种能被CenpG抗血清识别的43kD蛋白质成分。结果表明,新近发现和命名的CenpG(或者还有其他相关成分)的差异表达可能与细胞恶性增殖有关。 相似文献
107.
108.
The effects of induction conditions on production of a soluble antitumor sFv in Escherichia coli 总被引:2,自引:0,他引:2
Jaymie R.Sawyer; Schlom Jeffrey; Kashmiri S. V. S. 《Protein engineering, design & selection : PEDS》1994,7(11):1401-1406
CC49 is a second generation monoclonal antibody(mAb) with highaffinity to a pancarcinoma antigen, TAG-72. A single-chain Fv(sFv)ofCC49 may have a role in managing human carcinomas. Most reportedsFvs have been expressed as insoluble products that must besolubilized and renatured. Soluble sFv expression is advantageousas activity can be assayed directly from the periplasmic fraction.Also, gene-level immunoconjugates may not be amenable to refoldingprotocols. Using a vector that carries the tac promoter andomp A signal, we have examined the effects of four variableson the expression and accumulation of soluble CC49 sFv: (i)linker sequence joining VL and VH, (ii) isopropylthio-ß-D-galactosideconcentration for induction, (iii) temprature, and (iv) theaddition of nonmetabolizable sugars to the medium. We have beenable to demonstrate, using rapidly prepared periplasmic extracts,that the yield of soluble sFv improves by the addition of 0.4Msucrose to the medium and by inducing expression with a verylow concentration of IPTG (0.020.03 mM). Under theseinduction conditions periplasmic extracts demonstrate increasedexpression of the sFv, as shown by the larger amount of a 27kDa band on SDS-polyacrylamide gel, and an increased abilityto inhibit binding of the mAb CC49 to immobilized tumor extracts. 相似文献
109.
Abstract— We have developed a process to fabricate optical components, such as a lens, prism, or diffuser, directly on to a glass substrate. Processes include precision mastering by diamond cutting and multi‐layer photopolymer (2P) molding to realize flat surfaces and the integration of multiple components with an alignment within a few micrometers. 相似文献
110.
An inversion relationship is clarified between lightness and brightness, and also between chroma and colorfulness under nonuniform illumination with different illuminance levels (high and low) within the same visual field. Brightness (or colorfulness) of object color with low lightness (or chroma) under high illuminance level is perceived higher than that of another object color with high lightness (or chroma) under low illuminance level. Two color images are given for showing the inversion phenomena on brightness–lightness and colorfulness–chroma between object colors under different illuminance levels. These color images are useful for making researchers on color understand the differences in concept between brightness and lightness, and also between colorfulness and chroma. In particular, the concept of colorfulness is important, but difficult to understand. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 372–377, 2007 相似文献