全文获取类型
收费全文 | 5541篇 |
免费 | 491篇 |
国内免费 | 175篇 |
专业分类
电工技术 | 221篇 |
技术理论 | 2篇 |
综合类 | 338篇 |
化学工业 | 1059篇 |
金属工艺 | 319篇 |
机械仪表 | 318篇 |
建筑科学 | 513篇 |
矿业工程 | 201篇 |
能源动力 | 133篇 |
轻工业 | 296篇 |
水利工程 | 92篇 |
石油天然气 | 406篇 |
武器工业 | 51篇 |
无线电 | 632篇 |
一般工业技术 | 664篇 |
冶金工业 | 269篇 |
原子能技术 | 33篇 |
自动化技术 | 660篇 |
出版年
2024年 | 28篇 |
2023年 | 107篇 |
2022年 | 166篇 |
2021年 | 247篇 |
2020年 | 204篇 |
2019年 | 170篇 |
2018年 | 181篇 |
2017年 | 212篇 |
2016年 | 182篇 |
2015年 | 231篇 |
2014年 | 282篇 |
2013年 | 380篇 |
2012年 | 380篇 |
2011年 | 398篇 |
2010年 | 335篇 |
2009年 | 289篇 |
2008年 | 289篇 |
2007年 | 265篇 |
2006年 | 300篇 |
2005年 | 238篇 |
2004年 | 169篇 |
2003年 | 138篇 |
2002年 | 125篇 |
2001年 | 99篇 |
2000年 | 93篇 |
1999年 | 130篇 |
1998年 | 121篇 |
1997年 | 107篇 |
1996年 | 79篇 |
1995年 | 62篇 |
1994年 | 48篇 |
1993年 | 36篇 |
1992年 | 28篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有6207条查询结果,搜索用时 15 毫秒
51.
针对实时监控系统中的运行设备或装置的异常报警信息,设计了基于GSM无线通讯的微机监测系统,实现了多故障远程短信息报警功能,介绍了系统的软硬件设计及主要功能;经应用测试,系统具有宴时性强、稳定性高、投入成本低等特点,能将信息同时发送至多个移动通信终端,已成功应用于农业温室大棚监控系统的实时故障报警,系统也可方便地应用于工厂生产线、金融、交通及家庭安全等方面的远程监测. 相似文献
52.
This paper studies optimal path problems integrated with the concept of second order stochastic dominance. These problems arise from applications where travelers are concerned with the trade off between the risks associated with random travel time and other travel costs. Risk-averse behavior is embedded by requiring the random travel times on the optimal paths to stochastically dominate that on a benchmark path in the second order. A general linear operating cost is introduced to combine link- and path-based costs. The latter, which is the focus of the paper, is employed to address schedule costs pertinent to late and early arrival. An equivalent integer program to the problem is constructed by transforming the stochastic dominance constraint into a finite number of linear constraints. The problem is solved using both off-the-shelf solvers and specialized algorithms based on dynamic programming (DP). Although neither approach ensures satisfactory performance for general large-scale problems, the numerical experiments indicate that the DP-based approach provides a computationally feasible option to solve medium-size instances (networks with several thousand links) when correlations among random link travel times can be ignored. 相似文献
53.
介绍一种梅山冶金公司板坯连同上应用的新型的结晶器液位控制系统,它由浮式式液位检测装置,RSE1000控制器和电动塞棒执行机构所组成,由法国SERT公司成套制造。 相似文献
54.
Miaomiao Shen Yanshen Nie Yueyue Chen Xiufeng Zhang Jie Zhao 《International journal of molecular sciences》2021,22(1)
Meiotic recombination 11 (Mre11) is a relatively conserved nuclease in various species. Mre11 plays important roles in meiosis and DNA damage repair in yeast, humans and Arabidopsis, but little research has been done on mitotic DNA replication and repair in rice. Here, it was found that Mre11 was an extensively expressed gene among the various tissues and organs of rice, and loss-of-function of Mre11 resulted in severe defects of vegetative and reproductive growth, including dwarf plants, abnormally developed male and female gametes, and completely abortive seeds. The decreased number of cells in the apical meristem and the appearance of chromosomal fragments and bridges during the mitotic cell cycle in rice mre11 mutant roots revealed an essential role of OsMre11. Further research showed that DNA replication was suppressed, and a large number of DNA strand breaks occurred during the mitotic cell cycle of rice mre11 mutants. The expression of OsMre11 was up-regulated with the treatment of hydroxyurea and methyl methanesulfonate. Moreover, OsMre11 could form a complex with OsRad50 and OsNbs1, and they might function together in non-homologous end joining and homologous recombination repair pathways. These results indicated that OsMre11 plays vital roles in DNA replication and damage repair of the mitotic cell cycle, which ensure the development and fertility of rice by maintaining genome stability. 相似文献
55.
56.
57.
Pengcheng Nie Fangfang Qu Lei Lin Yong He Xuping Feng Liang Yang Huaqi Gao Lihua Zhao Lingxia Huang 《International journal of molecular sciences》2021,22(7)
Molecular spectroscopy has been widely used to identify pesticides. The main limitation of this approach is the difficulty of identifying pesticides with similar molecular structures. When these pesticide residues are in trace and mixed states in plants, it poses great challenges for practical identification. This study proposed a state-of-the-art method for the rapid identification of trace (10 mg·L−1) and multiple similar benzimidazole pesticide residues on the surface of Toona sinensis leaves, mainly including benzoyl (BNL), carbendazim (BCM), thiabendazole (TBZ), and their mixtures. The new method combines high-throughput terahertz (THz) imaging technology with a deep learning framework. To further improve the model reliability beyond the THz fingerprint peaks (BNL: 0.70, 1.07, 2.20 THz; BCM: 1.16, 1.35, 2.32 THz; TBZ: 0.92, 1.24, 1.66, 1.95, 2.58 THz), we extracted the absorption spectra in frequencies of 0.2–2.2 THz from images as the input to the deep convolution neural network (DCNN). Compared with fuzzy Sammon clustering and four back-propagation neural network (BPNN) models (TrainCGB, TrainCGF, TrainCGP, and TrainRP), DCNN achieved the highest prediction accuracies of 100%, 94.51%, 96.26%, 94.64%, 98.81%, 94.90%, 96.17%, and 96.99% for the control check group, BNL, BCM, TBZ, BNL + BCM, BNL + TBZ, BCM + TBZ, and BNL + BCM + TBZ, respectively. Taking advantage of THz imaging and DCNN, the image visualization of pesticide distribution and residue types on leaves was realized simultaneously. The results demonstrated that THz imaging and deep learning can be potentially adopted for rapid-sensing detection of trace multi-residues on leaf surfaces, which is of great significance for agriculture and food safety. 相似文献
58.
Ali Raza Wei Su Ang Gao Sundas Saher Mehmood Muhammad Azhar Hussain Wenlong Nie Yan Lv Xiling Zou Xuekun Zhang 《International journal of molecular sciences》2021,22(8)
Catalase (CAT) is an antioxidant enzyme expressed by the CAT gene family and exists in almost all aerobic organisms. Environmental stresses induce the generation of reactive oxygen species (ROS) that eventually hinder plant growth and development. The CAT enzyme translates the hydrogen peroxide (H2O2) to water (H2O) and reduce the ROS levels to shelter the cells’ death. So far, the CAT gene family has not been reported in rapeseed (Brassica napus L.). Therefore, a genome-wide comprehensive analysis was conducted to classify the CAT genes in the rapeseed genome. The current study identified 14 BnCAT genes in the rapeseed genome. Based on phylogenetic and synteny analysis, the BnCATs belong to four groups (Groups I–IV). A gene structure and conserved motif analysis showed that Group I, Group II, and Group IV possess almost the same intron/exon pattern, and an equal number of motifs, while Group III contains diverse structures and contain 15 motifs. By analyzing the cis-elements in the promoters, we identified five hormone-correlated responsive elements and four stress-related responsive elements. Further, six putative bna-miRNAs were also identified, targeting three genes (BnCAT4, BnCAT6, and BnCAT8). Gene ontology (GO) enrichment analysis showed that the BnCAT genes were largely related to cellular organelles, ROS response, stimulus response, stress response, and antioxidant enzymes. Almost 10 BnCAT genes showed higher expression levels in different tissues, i.e., root, leaf, stem, and silique. The expression analysis showed that BnCAT1–BnCAT3 and BnCAT11–BnCAT13 were significantly upregulated by cold, salinity, abscisic acid (ABA), and gibberellic acid (GA) treatment, but not by drought and methyl jasmonate (MeJA). Notably, most of the genes were upregulated by waterlogging stress, except BnCAT6, BnCAT9, and BnCAT10. Our results opened new windows for future investigations and provided insights into the CAT family genes in rapeseed. 相似文献
59.
Nie Zuoren Zhang Xinming Yin Zhimin Department of Materials Science Engineering Central South University of Technology Changsha 《中国有色金属学会会刊》1997,(3)
MICROSTRUCTURESANDTEXTURESINCOLDROLLEDALUMINIUMSTRIP①NieZuoren,ZhangXinming,YinZhiminDepartmentofMaterialsScienceandEngineri... 相似文献
60.
history dependent forming limits of sheet metals are computed by examining the role of rate sensitivity of flow stress in forming limits for anisotropic materials. Assuming that necking or nonuniform deformation is caused by initial heterogeneity, the forming limits are computed by considering the flow theory and incorporating an isotropic hardening model for anisotropic materials. Representative results show some of the trends for changing forming limits with different parameters under complex nonproportional loading histories. The computed results agree well with published experimental data for different loading history, anisotropy, and rate sensitivity of sheet materials. 相似文献