全文获取类型
收费全文 | 5999篇 |
免费 | 568篇 |
国内免费 | 319篇 |
专业分类
电工技术 | 1577篇 |
综合类 | 823篇 |
化学工业 | 366篇 |
金属工艺 | 91篇 |
机械仪表 | 118篇 |
建筑科学 | 1106篇 |
矿业工程 | 296篇 |
能源动力 | 469篇 |
轻工业 | 170篇 |
水利工程 | 384篇 |
石油天然气 | 313篇 |
武器工业 | 10篇 |
无线电 | 129篇 |
一般工业技术 | 235篇 |
冶金工业 | 282篇 |
原子能技术 | 14篇 |
自动化技术 | 503篇 |
出版年
2024年 | 8篇 |
2023年 | 62篇 |
2022年 | 139篇 |
2021年 | 172篇 |
2020年 | 211篇 |
2019年 | 164篇 |
2018年 | 132篇 |
2017年 | 142篇 |
2016年 | 187篇 |
2015年 | 208篇 |
2014年 | 317篇 |
2013年 | 295篇 |
2012年 | 365篇 |
2011年 | 428篇 |
2010年 | 328篇 |
2009年 | 424篇 |
2008年 | 392篇 |
2007年 | 523篇 |
2006年 | 461篇 |
2005年 | 403篇 |
2004年 | 318篇 |
2003年 | 290篇 |
2002年 | 203篇 |
2001年 | 177篇 |
2000年 | 140篇 |
1999年 | 101篇 |
1998年 | 59篇 |
1997年 | 53篇 |
1996年 | 33篇 |
1995年 | 39篇 |
1994年 | 32篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1959年 | 1篇 |
1958年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有6886条查询结果,搜索用时 93 毫秒
1.
Asami Nishikori Yoshito Nishimura Rei Shibata Koh-ichi Ohshima Yuka Gion Tomoka Ikeda Midori Filiz Nishimura Tadashi Yoshino Yasuharu Sato 《International journal of molecular sciences》2021,22(8)
Immunoglobulin G4-related disease (IgG4-RD) is a systemic disorder characterized by tissue fibrosis and intense lymphoplasmacytic infiltration, causing progressive organ dysfunction. Activation-induced cytidine deaminase (AID), a deaminase normally expressed in activated B-cells in germinal centers, edits ribonucleotides to induce somatic hypermutation and class switching of immunoglobulin. While AID expression is strictly controlled under physiological conditions, chronic inflammation has been noted to induce its upregulation to propel oncogenesis. We examined AID expression in IgG4-related ophthalmic disease (IgG4-ROD; n = 16), marginal zone lymphoma with IgG4-positive cells (IgG4+ MZL; n = 11), and marginal zone lymphoma without IgG4-positive cells (IgG4- MZL; n = 12) of ocular adnexa using immunohistochemical staining. Immunohistochemistry revealed significantly higher AID-intensity index in IgG4-ROD and IgG4+ MZL than IgG4- MZL (p < 0.001 and = 0.001, respectively). The present results suggest that IgG4-RD has several specific causes of AID up-regulation in addition to inflammation, and AID may be a driver of oncogenesis in IgG4-ROD to IgG4+ MZL. 相似文献
2.
Elli Ntakou Ralph Masiello Farnaz Farzan Shay Bahramirad Aleksi Paaso M.A. Nayeem Maigha Maigha Daniel Kushner 《The Electricity Journal》2019,32(4):45-49
This paper presents part of the work ComEd and Quanta Technology have performed to quantify the locational and temporal value of DER to avoid distribution grid upgrade investments. It focuses on the formulation of a robust and efficient algorithm for DER optimal dispatch on a distribution feeder to mitigate the violation of current and voltage limits using the allocated cost of capacity and locational marginal value of real and reactive DER injection/withdrawal. 相似文献
3.
针对我国建材行业传统使用的常压固定床煤气发生炉及化肥行业固定床间歇气化炉面临淘汰,无烟煤市场萎缩的情况,提出以晋城无烟煤为原料,利用赛鼎碎煤加压气化技术,生产适合建材行业大规模使用的工业燃气。以无烟煤为原料的河北沙河年产26亿m^3工业清洁燃气项目为基础,对无烟煤与天然气价格、项目经济性的关系进行了分析,结果表明,以晋城无烟块煤运到河北沙河的到厂价935元/t计算,盈亏平衡天然气价约2.26元/m^3;以沙河工业天然气到户售价2.5元/m^3计算,盈亏平衡到厂煤价约1 077元/t,项目经济性较好。 相似文献
4.
鉴于分布式能源的出力性质为间歇性和波动性,影响电网安全高效运行,而虚拟电厂可解决此问题。对虚拟电厂进行申报-调度两阶段建模,以包含分布式电源(光电、风电和燃气轮机)和储能系统(储能电池)两大类分布式能源的虚拟电厂为例,基于光照强度及风速等不确定因素,研究峰谷分时电价下日前市场虚拟电厂的出力申报和运行调度策略并利用风险价值模型进行风险管理。结果表明,申报出力时,当电价激励足够高时储能电池方会参与出力,成功起到削峰填谷的作用;运行调度时,平衡出力偏差方面,储能电池发挥主要作用,且虚拟电厂运行调度策略具有一定的经济效益。 相似文献
5.
为提高矿山工程建设项目造价管理水平,设计了矿山工程建设项目造价管理系统。通过分析矿山工程项目的造价组成,并采用三层B/S架构设计系统硬件框架,运用Web服务器传输矿山工程项目各项数据,划分系统功能子系统,并对矿山工程建设项目造价额与价差预备费进行计算,完成系统软件设计。结果表明,该系统能够有效管理矿山工程建设项目造价,并对外部的恶意攻击进行及时报警,系统具有有效性与安全性。 相似文献
6.
7.
This note reconsiders the marginal density of a threshold moving average process and proposes a simple yet effective numerical algorithm to implement that by solving an associated integral equation. This algorithm can also be applied to calculate stationary probability density or distribution functions of a few other types of nonlinear stationary stochastic processes numerically. 相似文献
8.
The proposed study investigates a continuous review inventory model with order quantity, reorder point, backorder price discount, process quality, and lead time as decision variables. An investment function is used to improve the process quality. Two models are developed based on the probability distribution of lead time demand. The lead time demand follows a normal distribution in the first model and in the second model it does not follow any specific distribution but mean and standard deviation are known. We prove two lemmas to obtain optimal solutions for the normal distribution model and distribution free model. Finally, some numerical examples are given to illustrate the model. 相似文献
9.
Distributed generation has been playing a vital role in dealing with issues related to distribution systems. This paper presents an approach which provides the distribution system operator with a set of solutions for DG placement to optimize reliability and total cost of power consumed by the distribution system. Optimal location of a Distributed Generator is evaluated based on the performance indices derived for reliability index and total cost of power consumed by the system. The proposed approach is applied to a 15-bus radial distribution system and a 18-bus radial distribution system and the results are analyzed. 相似文献
10.
In this paper, we study scheduling games under mixed coordination mechanisms on hierarchical machines. The two scheduling policies involved are ‐ and ‐, where ‐ (resp., ‐) policy sequences jobs in nondecreasing order of their hierarchies, and jobs of the same hierarchy in nonincreasing (resp., nondecreasing) order of their processing times. We first show the existence of a Nash equilibrium. Then we present the price of anarchy and the price of stability for the games with social costs of minimizing the makespan and maximizing the minimum machine load. All the bounds given in this paper are tight. 相似文献