全文获取类型
收费全文 | 8053篇 |
免费 | 550篇 |
国内免费 | 421篇 |
专业分类
电工技术 | 571篇 |
综合类 | 642篇 |
化学工业 | 67篇 |
金属工艺 | 50篇 |
机械仪表 | 232篇 |
建筑科学 | 123篇 |
矿业工程 | 70篇 |
能源动力 | 39篇 |
轻工业 | 52篇 |
水利工程 | 32篇 |
石油天然气 | 39篇 |
武器工业 | 28篇 |
无线电 | 2919篇 |
一般工业技术 | 166篇 |
冶金工业 | 71篇 |
原子能技术 | 33篇 |
自动化技术 | 3890篇 |
出版年
2024年 | 6篇 |
2023年 | 23篇 |
2022年 | 37篇 |
2021年 | 59篇 |
2020年 | 74篇 |
2019年 | 59篇 |
2018年 | 62篇 |
2017年 | 91篇 |
2016年 | 102篇 |
2015年 | 146篇 |
2014年 | 304篇 |
2013年 | 278篇 |
2012年 | 422篇 |
2011年 | 501篇 |
2010年 | 411篇 |
2009年 | 533篇 |
2008年 | 632篇 |
2007年 | 718篇 |
2006年 | 734篇 |
2005年 | 737篇 |
2004年 | 632篇 |
2003年 | 674篇 |
2002年 | 556篇 |
2001年 | 414篇 |
2000年 | 320篇 |
1999年 | 169篇 |
1998年 | 83篇 |
1997年 | 52篇 |
1996年 | 49篇 |
1995年 | 32篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1964年 | 1篇 |
排序方式: 共有9024条查询结果,搜索用时 15 毫秒
1.
2.
Irena Dapic Lucia Baljeu‐Neuman Naomi Uwugiaren Jesper Kers David R. Goodlett Garry L. Corthals 《Mass spectrometry reviews》2019,38(4-5):403-441
Tissues and biofluids are important sources of information used for the detection of diseases and decisions on patient therapies. There are several accepted methods for preservation of tissues, among which the most popular are fresh‐frozen and formalin‐fixed paraffin embedded methods. Depending on the preservation method and the amount of sample available, various specific protocols are available for tissue processing for subsequent proteomic analysis. Protocols are tailored to answer various biological questions, and as such vary in lysis and digestion conditions, as well as duration. The existence of diverse tissue‐sample protocols has led to confusion in how to choose the best protocol for a given tissue and made it difficult to compare results across sample types. Here, we summarize procedures used for tissue processing for subsequent bottom‐up proteomic analysis. Furthermore, we compare protocols for their variations in the composition of lysis buffers, digestion procedures, and purification steps. For example, reports have shown that lysis buffer composition plays an important role in the profile of extracted proteins: the most common are tris(hydroxymethyl)aminomethane, radioimmunoprecipitation assay, and ammonium bicarbonate buffers. Although, trypsin is the most commonly used enzyme for proteolysis, in some protocols it is supplemented with Lys‐C and/or chymotrypsin, which will often lead to an increase in proteome coverage. Data show that the selection of the lysis procedure might need to be tissue‐specific to produce distinct protocols for individual tissue types. Finally, selection of the procedures is also influenced by the amount of sample available, which range from biopsies or the size of a few dozen of mm2 obtained with laser capture microdissection to much larger amounts that weight several milligrams. 相似文献
3.
Determining patent filing targets based on patent cost retrieval from Patent Examination Data System
I have utilized Patent Examination Data System (PEDS) to propose a patent filing strategy decomposed by sub-divisions within a Research and Development (R&D) department of a large organization. The unique method relies on breaking the patent cost into fixed cost and variable cost. The variable cost is determined by automatically retrieving data from PEDS. The data includes historical average of number of interactions of a patent applicant with the patent office, grouped by technology domains. The variable cost may then be used in a linear programming model to obtain optimal filing targets for each sub-division within the R&D department. The proposed strategy will help an organization to take objective decisions for determining patent filing targets for its sub-divisions, which will eventually help with an efficient patent strategy for the organization. 相似文献
4.
Gianvito Difilippo Maria Pia Fanti Agostino Marcello Mangini 《IEEE/CAA Journal of Automatica Sinica》2022,9(2):259-269
The paper deals with the consensus problem in a leaderless network of agents that have to reach a common velocity while forming a uniformly spaced string. Moreover, the final common velocity (reference velocity) is determined by the agents in a distributed and leaderless way. Then, the consensus protocol parameters are optimized for networks characterized by a communication topology described by a class of directed graphs having a directed spanning tree, in order to maximize the convergence rate and avoid oscillations. The advantages of the optimized consensus protocol are enlightened by some simulation results and comparison with a protocol proposed in the related literature. The presented protocol can be applied to coordinate agents such as mobile robots, automated guided vehicles (AGVs) and autonomous vehicles that have to move with the same velocity and a common inter-space gap. 相似文献
5.
The 9‐point hedonic scale and hedonic ranking in food science: some reappraisals and alternatives 下载免费PDF全文
Sukanya Wichchukit Michael O'Mahony 《Journal of the science of food and agriculture》2015,95(11):2167-2178
The 9‐point hedonic scale has been used routinely in food science, the same way for 60 years. Now, with advances in technology, data from the scale are being used for more and more complex programs for statistical analysis and modeling. Accordingly, it is worth reconsidering the presentation protocols and the analyses associated with the scale, as well as some alternatives. How the brain generates numbers and the types of numbers it generates has relevance for the choice of measurement protocols. There are alternatives to the generally used serial monadic protocol, which can be more suitable. Traditionally, the ‘words’ on the 9‐point hedonic scale are reassigned as ‘numbers’, while other ‘9‐point hedonic scales’ are purely numerical; the two are not interchangeable. Parametric statistical analysis of scaling data is examined critically and alternatives discussed. The potential of a promising alternative to scaling itself, simple ranking with a hedonic R‐Index signal detection analysis, is explored in comparison with the 9‐point hedonic scale. © 2014 Society of Chemical Industry 相似文献
6.
The last decade has seen a growing interest in hybrid electrically conducting nanocomposites. This article aims to provide a detailed overview of the present status of research in carbon nanotube–polyaniline (CNT/PANI) composites, from processing to structural and property evaluations. CNT/PANI are synthesized by electrochemical and chemical processing. When chemical methods are used, the main challenge is to obtain processable CNT/PANI in the emeraldine salt (ES) form composites. Stable dispersions of ES–CNT in organic media are prepared using the post doping method, inverse emulsion polymerization, or ex situ polymerizations. On the contrary, stable water dispersions of CNT/ES are prepared using hydrophilization of a preformed CNT/ES composite, direct synthesis of micelle–CNT hybrid templates, interfacial polymerization, covalent functionalization of CNT with a water soluble polymer, or using electrostatic interactions between two oppositely charged ES and CNT aqueous colloids. Moreover, the strategies for the synthesis of ternary CNT/PANI composites incorporating noble metal nanoparticles, metal oxide, or graphene sheets are also presented and analyzed in depth. Finally, we give a review of potential applications, including chemical sensors, capacitors, fuel cells and electronic devices. 相似文献
7.
本文介绍了非开挖技术施工工艺在城市污水管道施工中具体的应用情况,解决了在市政建设中传统开挖技术所无法解决的问题,取得了很好的经济效益和社会效应。 相似文献
8.
9.
矿区煤层为走向近东西急倾斜的单斜产出,埋藏深度5 m左右,埋藏浅。经物性测定煤层整体表现为高阻、中高极化"两高"的地球物理特征。区内地势平缓,侏罗系受后期岩浆热液侵入和构造断裂变质作用不明显。地面干扰因素极为有限,为找寻隐伏煤层提供了地球物理前提。时间域激发极化法,通过激电中梯测量圈定激电异常,划定煤层范围和位置,通过激电测深,可定性、定量计算出隐伏矿床的产状、埋深、规模及空间展布特征等参数。后经钻探验证与推测煤层位置及深度基本吻合。按不同的工程网度求取资源量,实现了较好的经济效益和社会效益。 相似文献
10.