全文获取类型
收费全文 | 29170篇 |
免费 | 2179篇 |
国内免费 | 1227篇 |
专业分类
电工技术 | 1359篇 |
技术理论 | 6篇 |
综合类 | 1939篇 |
化学工业 | 5114篇 |
金属工艺 | 1826篇 |
机械仪表 | 1801篇 |
建筑科学 | 2260篇 |
矿业工程 | 794篇 |
能源动力 | 792篇 |
轻工业 | 1675篇 |
水利工程 | 497篇 |
石油天然气 | 1956篇 |
武器工业 | 159篇 |
无线电 | 3172篇 |
一般工业技术 | 3675篇 |
冶金工业 | 1570篇 |
原子能技术 | 390篇 |
自动化技术 | 3591篇 |
出版年
2024年 | 109篇 |
2023年 | 470篇 |
2022年 | 741篇 |
2021年 | 1059篇 |
2020年 | 806篇 |
2019年 | 680篇 |
2018年 | 772篇 |
2017年 | 842篇 |
2016年 | 840篇 |
2015年 | 996篇 |
2014年 | 1339篇 |
2013年 | 1642篇 |
2012年 | 1670篇 |
2011年 | 1924篇 |
2010年 | 1732篇 |
2009年 | 1675篇 |
2008年 | 1585篇 |
2007年 | 1425篇 |
2006年 | 1423篇 |
2005年 | 1286篇 |
2004年 | 973篇 |
2003年 | 996篇 |
2002年 | 1054篇 |
2001年 | 1022篇 |
2000年 | 792篇 |
1999年 | 868篇 |
1998年 | 725篇 |
1997年 | 576篇 |
1996年 | 521篇 |
1995年 | 428篇 |
1994年 | 375篇 |
1993年 | 265篇 |
1992年 | 208篇 |
1991年 | 153篇 |
1990年 | 119篇 |
1989年 | 105篇 |
1988年 | 75篇 |
1987年 | 51篇 |
1986年 | 54篇 |
1985年 | 24篇 |
1984年 | 29篇 |
1983年 | 27篇 |
1982年 | 20篇 |
1981年 | 19篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 5篇 |
1976年 | 13篇 |
1970年 | 6篇 |
1966年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
应用不同剂量的~(60)Coγ射线照射含NT株弓形虫包囊的鼠脑匀浆后,以0.4%胰蛋白酶液消化,使弓形虫缓殖子从包囊中释放出来,并用生理盐水作连续10倍稀释,使成为含不同数量缓殖子的悬液,将此悬液接种小鼠,用生物检测方法确定其感染性。另设未经照射处理的缓殖子悬液感染小鼠的对照组。结果表明,γ射线0.55kGy剂量为控制鼠脑中NT株弓形虫感染性的最小有效剂量。γ射线0.1kGy剂量对弓形虫缓殖子感染性无明显影响,而0.45kGy照射后,其感染性较前者下降了10~4倍。 相似文献
12.
13.
To pick up serum high risk lithogenic factors predisposing one to gallstone formation and protective factors against gallstone formation in gallbladder. We compared serum lipid and apolipoprotein level of patients with gallbladder stone (stone group) with that of patients without gallbladder stone (control group). The correlation between serum lipid, apolipoprotein level and bile lipid level, cholesterol saturated index (CSI), characteristics of lipidemia in different kinds of gallbladder stones were studied. The results showed that the increase of serum Apo A1, C2 and E level in the stone group was more significant than in the control group. But there was no statistical significance in TC, TG, LDL-C, HDL-C, Apo A2, B, C3 level between the stone and control groups. These results suggested that serum apolipoproteins perhaps are more sensitive parameters than serum lipids in distinguishing patients with stones from those without stones. There were different profiles of serum lipid and apolipoproteins in different chemical types of gallbladder stones. Increased level in serum LDL-C, Apo B and ratio of LDL-C/HDL-C were characterized by an index for cholesterol stone, otherwise that in serum TG and Apo C2 an index for pigment stones. There was a positive correlation between serum total cholesterol (TC) or Apo B, C2, C3 and cholesterol amount or CSI in gallbladder bile. Therefore, TC, Apo B, C2, C3 could be considered as high risk lithogenic factors. A positive correlation existed between serum HDL-C and lecithin in gallbladder or common bile duct (CBD) bile as well as between HDL-C and bile acids in CBD bile. Thus, HDL-C might be a protective factor against gallstone formation in gallbladder. 相似文献
14.
以氧化锰矿粉为原料,添加ZB粘结剂进行冷固成团,所得冷固团块不仅具有足够的机械强度,而且具有良好的耐湿性,适用于长距离运输和露天堆存,是一种可与块矿性能相媲美的优质炉料,为充分利用矿山及冶炼厂的锰矿粉找到了一条良好的途径. 相似文献
15.
Minyue Fu 《International Journal of Adaptive Control and Signal Processing》2006,20(5):197-211
The switching adaptive control method has been used for quite a few years to solve the adaptive stabilization and model reference adaptive control problems. However, a serious problem with the switching control method is that the number of ‘candidate’ controllers can potentially be very large, especially for multi‐input–multi‐output systems. In this paper, we consider a class of minimum‐phase multi‐input–multi‐output plants with some mild compactness assumptions. Given any polynomial reference input, we provide a switching control law which guarantees exponentially stability of the closed‐loop system with exponential tracking performance. The main contribution of the paper is that we give the minimum number of candidate controllers required for switching. In particular, the number is equal to 2 for single‐input–single‐output plants (one for each sign of the high‐frequency gain), and is equal to 2m for m‐input–m‐output plants. That is, the number is independent of the degree and the relative degree of the plant. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
16.
Tien-Hsiang Sun Chao-Weng Cheng Li-Chen Fu 《Industrial Electronics, IEEE Transactions on》1994,41(6):593-601
In this paper, a timed-place Petri net (TPPN) model for flexible manufacturing systems (FMSs) is constructed, which contains two major submodels: the stationary transportation model; and the variable process flow model. For multiple automated guided vehicle (AGV) systems, the authors embed a simple rule and introduce a push-AGV strategy in a TPPN model to solve the collision and traffic jam problems of such vehicles. Since a firing sequence of the TPPN from the initial marking to the final marking can be seen as a schedule of the modeled FMS, by using an A* based search algorithm, namely, the limited-expansion A algorithm, an effective schedule of the part processing can be obtained. To show the promising potential of the proposed work, a prototype FMS is used as a target system for implementation. The experiment results assert that the job-shop scheduling problem can always be satisfactorily solved 相似文献
17.
Shye Lin Wu Chung Len Lee Tan Fu Lei Chen C.F. Chen L.J. Ho K.Z. Ling Y.C. 《Electron Device Letters, IEEE》1994,15(4):120-122
In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p+-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900°C. As a result, the junction depth of the BF2-implanted device is much larger than that of the boron-implanted device 相似文献
18.
傅文祖 《有色金属材料与工程》1994,15(5):300-307
连续挤压法的特点是:挤压所需的压力是借助一个回转的摩擦轮来实现的。摩擦轮的轮缘上设有一个凹槽,其断面取决于原坯的断面(线材坯料)。本文将就这种工艺的设备和有关铝材生产阶段中的一些问题作一简介。 相似文献
19.
本文论述了局部施肥对植株地上部与地下部的影响。局部施肥促进了施肥区根系的发达 ,第一侧根与第二侧根较多 ,根的吸收表面积增多 ,根鲜重增加 ,对养分的吸收能力增强 ,但整个根系与地上部的干鲜重下降。 相似文献
20.