首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3833篇
  免费   188篇
  国内免费   9篇
电工技术   55篇
综合类   2篇
化学工业   1065篇
金属工艺   55篇
机械仪表   93篇
建筑科学   194篇
矿业工程   3篇
能源动力   155篇
轻工业   565篇
水利工程   43篇
石油天然气   43篇
无线电   267篇
一般工业技术   533篇
冶金工业   160篇
原子能技术   14篇
自动化技术   783篇
  2024年   11篇
  2023年   45篇
  2022年   116篇
  2021年   171篇
  2020年   103篇
  2019年   137篇
  2018年   144篇
  2017年   118篇
  2016年   187篇
  2015年   90篇
  2014年   168篇
  2013年   322篇
  2012年   257篇
  2011年   320篇
  2010年   236篇
  2009年   249篇
  2008年   220篇
  2007年   171篇
  2006年   125篇
  2005年   93篇
  2004年   99篇
  2003年   75篇
  2002年   81篇
  2001年   47篇
  2000年   34篇
  1999年   43篇
  1998年   44篇
  1997年   46篇
  1996年   31篇
  1995年   33篇
  1994年   28篇
  1993年   19篇
  1992年   26篇
  1991年   14篇
  1990年   15篇
  1989年   16篇
  1988年   18篇
  1987年   8篇
  1986年   5篇
  1985年   9篇
  1984年   9篇
  1983年   8篇
  1982年   3篇
  1981年   7篇
  1980年   7篇
  1979年   3篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1962年   1篇
排序方式: 共有4030条查询结果,搜索用时 10 毫秒
81.
Leptosphaeria maculans causes blackleg disease, which is one of the most destructive diseases of canola (Brassica napus L.). Due to the erosion of the current resistance in B. napus, it is pivotal to introduce new resistant genotypes to the growers. This study evaluated the potential of Rlm7 gene as resistance to its corresponding avirulence AvrLm7 gene is abundant. The Rlm7 line was inoculated with L. maculans isolate with AvrLm7; UMAvr7; and the CRISPR/Cas9 knockout AvrLm7 mutant, umavr7, of the same isolate to cause incompatible and compatible interactions, respectively. Dual RNA-seq showed differential gene expressions in both interactions. High expressions of virulence-related pathogen genes-CAZymes, merops, and effector proteins after 7-dpi in compatible interactions but not in incompatible interaction—confirmed that the pathogen was actively virulent only in compatible interactions. Salicyclic and jasmonic acid biosynthesis and signaling-related genes, defense-related PR1 gene (GSBRNA2T00150001001), and GSBRNA2T00068522001 in the NLR gene family were upregulated starting as early as 1- and 3-dpi in the incompatible interaction and the high upregulation of those genes after 7-dpi in compatible interactions confirmed the early recognition of the pathogen by the host and control it by early activation of host defense mechanisms in the incompatible interaction.  相似文献   
82.
Sofrito is a key component of the Mediterranean diet, a diet that is strongly associated with a reduced risk of cardiovascular events. In this study, different Mediterranean sofritos were analysed for their content of polyphenols and carotenoids after a suitable work-up extraction procedure using liquid chromatography/electrospray ionisation-linear ion trap quadrupole-Orbitrap-mass spectrometry (LC/ESI-LTQ-Orbitrap-MS) and liquid chromatography/electrospray ionisation tandem triple quadrupole mass spectrometry (LC/ESI-MS-MS). In this way, 40 polyphenols (simple phenolic and hydroxycinnamoylquinic acids, and flavone, flavonol and dihydrochalcone derivatives) were identified with very good mass accuracy (<2 mDa), and confirmed by accurate mass measurements in MS and MS2 modes. The high-resolution MS analyses revealed the presence of polyphenols never previously reported in Mediterranean sofrito. The quantification levels of phenolic and carotenoid compounds led to the distinction of features among different Mediterranean sofritos according to the type of vegetables (garlic and onions) or olive oil added for their production.  相似文献   
83.
Drug-induced liver injury (DILI) is one of the leading causes of acute liver injury. Many factors may contribute to the susceptibility of patients to this condition, making DILI a global medical problem that has an impact on public health and the pharmaceutical industry. The use of mesenchymal stem cells (MSCs) has been at the forefront of regenerative medicine therapies for many years, including MSCs for the treatment of liver diseases. However, there is currently a huge gap between these experimental approaches and their application in clinical practice. In this concise review, we focus on the pathophysiology of DILI and highlight new experimental approaches conceived to improve cell-based therapy by the in vitro preconditioning of MSCs and/or the use of cell-free products as treatment for this liver condition. Finally, we discuss the advantages of new approaches, but also the current challenges that must be addressed in order to develop safer and more effective procedures that will allow cell-based therapies to reach clinical practice, enhancing the quality of life and prolonging the survival time of patients with DILI.  相似文献   
84.
85.
Recovery capability of bituminous materials plays a significant role in the development of new technologies for extending the service life of asphalt pavements. This capability originates from various phenomena such as thixotropy, cooling, relaxation of hardening, or healing. However, their real effect on mechanical response is not clear. This article aims to investigate how rest periods (RPs) available between traffic loads can contribute to the damage recovery of bituminous materials. For this purpose, different types and durations of RPs were applied during the laboratory evaluation of fatigue resistance of these materials using the University of Granada Fatigue Asphalt Cracking Test method. The results indicate that the addition of RPs to the loading regime could lead to an extension in the fatigue life of bituminous materials. Additionally, an increase in the RP duration showed a positive impact on the resistance of the materials against cyclic loading. Nonetheless, these benefits are not only related to the recovery of lost properties during RPs, but also a growth in the amount of plastic deformations as a result of the applying RPs could delay the appearance of damages (i.e. cracking). Consequently, the bituminous material can tolerate a higher number of load cycles during fatigue test.  相似文献   
86.
A complete characterization of the stability boundary of an asymptotically stable equilibrium point in the presence of type-k saddle-node non-hyperbolic equilibrium points, with k ≥ 0, on the stability boundary is developed in this paper. Under the transversality condition, it is shown that the stability boundary is composed of the stable manifolds of the hyperbolic equilibrium points on the stability boundary, the stable manifolds of type-0 saddle-node equilibrium points on the stability boundary and the stable centre and centre manifolds of the type-r saddle-node equilibrium points with r ≥ 1 on the stability boundary. This characterization is the first step to understanding the behaviour of stability regions and stability boundaries in the occurrence of saddle-node bifurcations on the stability boundary.  相似文献   
87.
The Journal of Supercomputing - Nowadays, cloud computing is a growing scenario applied to many scientific and manufacturing areas due to its flexibility for adapting to highly demanding computing...  相似文献   
88.
The purpose of this paper is to present an extension of the generalised supertwisting algorithm (STA) to the multivariable framework. We begin by introducing an algorithm that may be deemed as a linear, quasicontinuous, or discontinuous multivariable system, depending on the functions that define them. For the class represented by such an algorithm we prove the robust, Lyapunov stability of the origin and characterise the perturbations that preserve its stability. In particular, when its vector field is discontinuous or quasicontinuous our algorithm is endowed with finite‐time stability. Due to its resemblance to the scalar case, we denote such finite‐time stable systems as generalised multivariable STA. Furthermore, the class of finite‐time stable systems comprise the currently available versions of STAs. To finalise, by means of simulation examples, we show that our proposed finite‐time stable algorithms are well suited for signals online differentiation and highlight their dynamical traits.  相似文献   
89.
The objective of this article is to provide a generalized framework of a novel method that investigates the problem of combining and fusing different types of measurements for pose estimation. The proposed method allows to jointly minimize the different metric errors as a single measurement vector in n-dimensions without requiring a scaling factor to tune their importance. This paper is an extended version of previous works that introduced the Point-to-hyperplane Iterative Closest Point (ICP) approach. In this approach, an increased convergence domain and a faster alignment were demonstrated by considering a four-dimensional measurement vector (3D Euclidean points + Intensity). The method has the advantages of the classic point-to-plane ICP method, but extends this to higher dimensions. For demonstration purposes, this paper will focus on a RGB-D sensor that provides colour and depth measurements simultaneously and an optimal error in higher dimensions will be minimized from this. Results on both, simulated and real environments will be provided and the performance of the proposed method will be carried on real-time visual SLAM.  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号