全文获取类型
收费全文 | 2395篇 |
免费 | 185篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 39篇 |
综合类 | 7篇 |
化学工业 | 639篇 |
金属工艺 | 43篇 |
机械仪表 | 61篇 |
建筑科学 | 91篇 |
矿业工程 | 5篇 |
能源动力 | 183篇 |
轻工业 | 334篇 |
水利工程 | 43篇 |
石油天然气 | 11篇 |
无线电 | 305篇 |
一般工业技术 | 422篇 |
冶金工业 | 56篇 |
原子能技术 | 12篇 |
自动化技术 | 339篇 |
出版年
2024年 | 8篇 |
2023年 | 74篇 |
2022年 | 138篇 |
2021年 | 237篇 |
2020年 | 144篇 |
2019年 | 119篇 |
2018年 | 167篇 |
2017年 | 157篇 |
2016年 | 166篇 |
2015年 | 114篇 |
2014年 | 154篇 |
2013年 | 191篇 |
2012年 | 158篇 |
2011年 | 191篇 |
2010年 | 109篇 |
2009年 | 103篇 |
2008年 | 55篇 |
2007年 | 52篇 |
2006年 | 46篇 |
2005年 | 38篇 |
2004年 | 27篇 |
2003年 | 31篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2590条查询结果,搜索用时 15 毫秒
991.
Owen Hudson James C. Fulton Alexi K. Dong Nicholas S. Dufault Md Emran Ali 《International journal of molecular sciences》2021,22(18)
Watermelon is an important commercial crop in the Southeastern United States and around the world. However, production is significantly limited by biotic factors including fusarium wilt caused by the hemibiotrophic fungus Fusarium oxysporum forma specialis niveum (Fon). Unfortunately, this disease has increased significantly in its presence over the last several decades as races have emerged which can overcome the available commercial resistance. Management strategies include rotation, improved crop resistance, and chemical control, but early and accurate diagnostics are required for appropriate management. Accurate diagnostics require molecular and genomic strategies due to the near identical genomic sequences of the various races. Bioassays exist for evaluating both the pathogenicity and virulence of an isolate but are limited by the time and resources required. Molecular strategies are still imperfect but greatly reduce the time to complete the diagnosis. This article presents the current state of the research surrounding races, both how races have been detected and diagnosed in the past and future prospects for improving the system of differentiation. Additionally, the available Fon genomes were analyzed using a strategy previously described in separate formae speciales avirulence gene association studies in Fusarium oxysporum races. 相似文献
992.
Katharina Schimmel Md Khadem Ali Serena Y. Tan Joyce Teng Huy M. Do Gary K. Steinberg David A. Stevenson Edda Spiekerkoetter 《International journal of molecular sciences》2021,22(16)
Arteriovenous malformations are a vascular anomaly typically present at birth, characterized by an abnormal connection between an artery and a vein (bypassing the capillaries). These high flow lesions can vary in size and location. Therapeutic approaches are limited, and AVMs can cause significant morbidity and mortality. Here, we describe our current understanding of the pathogenesis of arteriovenous malformations based on preclinical and clinical findings. We discuss past and present accomplishments and challenges in the field and identify research gaps that need to be filled for the successful development of therapeutic strategies in the future. 相似文献
993.
Song Hana Yoon Jae-Hyun Choi Yun-Sun Han Areum Kim Ji-Yeon Kim Ju-Hee Hyun Jeong-Eun Bae Young-Min Huq Md. Amdadul Choi Changsun Park Ki-Hwan Lee Sun-Young 《Food science and biotechnology》2019,28(4):1265-1274
Food Science and Biotechnology - In this study, a total of 195 samples including fresh produce and farming environments was used to perform the microbial risk assessment. Levels of total aerobic... 相似文献
994.
Md Soriful Islam Most Mauluda Akhtar James H. Segars 《Critical reviews in food science and nutrition》2017,57(17):3583-3600
Uterine fibroids (myomas or leiomyomas) are common benign tumors of reproductive aged women. Fibroids are clinically apparent in 20–50% of women, and cause abnormal uterine bleeding, abdominal pain and discomfort, pregnancy complications and infertility. Unfortunately, limited numbers of medical treatment are available but no effective preventive strategies exist. Moreover, the benefits of medical treatments are tempered by lack of efficacy or serious adverse side effects. Fibrosis has recently been recognized as a key pathological event in leiomyoma development and growth. It is defined by the excessive deposition of extracellular matrix (ECM). ECM plays important role in making bulk structure of leiomyoma, and ECM-rich rigid structure is believed to be a cause of abnormal bleeding and pelvic pain/pressure. Dietary phytochemicals are known to regulate fibrotic process in different biological systems, and being considered as potential tool to manage human health. At present, very few dietary phytochemicals have been studied in uterine leiomyoma, and they are mostly known for their antiproliferative effects. Therefore, in this review, our aim was to introduce some dietary phytochemicals that could target fibrotic processes in leiomyoma. Thus, this review could serve as useful resource to develop antifibrotic drugs for possible prevention and treatment of uterine fibroids. 相似文献
995.
Md. Shahjahan Kaisar Alam Sarkar S.W. Donne G.M. Evans 《Advanced Powder Technology》2010,21(4):412-418
In this study the flotation recovery of silica using air, and molecular and electrolytically-generated hydrogen was investigated. For comparison of air and molecular hydrogen recoveries, a laboratory Denver, type D12, flotation machine was used. For both gases, pH of the suspension, gas flow rate, concentration of collector and frother, solids concentration, particle size and speed of impeller were kept constant. Almost identical recoveries were obtained for both gases, suggesting that gas composition played no significant role in silica flotation. Electroflotation experiments were carried out using 12.6 μm mean diameter silica particles. While fine particles had very poor recovery in the Denver cell, greater than 70% recoveries were achieved in the electroflotation cell. This was thought to be the result of the very small (less than 40 μm) bubbles generated by the electroflotation process. A population-balance model, incorporating the hydrogen generation process, supported the conclusion that increased recovery for electroflotation, for very fine silica particles at least, was attributed to the reduced bubble size and not by the composition of the gas. 相似文献
996.
Ababneh ZQ Ababneh R Maier SE Winalski CS Oshio K Ababneh AM Mulkern RV 《Magma (New York, N.Y.)》2008,21(4):273-278
PURPOSE: To assess the transverse relaxation time T(2) and diffusion coefficient D before and following exercise in the tibialis anterior muscle and determine whether T(2) and D values were correlated. METHODS: Measurements of T(2) and D were performed at 3 T within axial slices through the calf muscles of six healthy volunteers at 95 s intervals before and for 10-12 min after a dorsiflexion exercise to exhaustion. RESULTS: The mean +/- standard deviation (SD) of T(2) and D before exercise were 32 +/- 1.55 ms and 1.52 +/- 0.15 mum(2)/ms, and after exercise were 43 +/- 2.5 ms and 1.72 +/- 0.13 mum(2)/ms, respectively. The mean +/- SD inter-individual recovery times of the % change in T(2) and D after exercise were 7.9 +/- 4.2 and 10.9 +/- 7.0 min, respectively. The T(2) and D values showed a significant correlation throughout the experiments (r (2) = 0.45). CONCLUSIONS: The increase in T(2) of skeletal muscle after exercise is correlated with the increase of the diffusion coefficient D and the recovery times appear similar, indicating that any model used to explain T(2) increases with exercise must also account for increased diffusion coefficients. 相似文献
997.
Md Shafiullah 《电力部件与系统》2017,45(8):807-824
Electricity customers are usually connected to the power system networks through distribution grids, and any interruption in these grids causes customer minute loss (CML). Most of the CMLs are caused due to different types of faults sustained for a longer period of time. Therefore, rapid fault location techniques are very necessary in order to restore the power supply quickly by reducing outage durations and revenue losses. To expedite restoration process and to ensure reliable power supply in traditional distribution networks, many fault location techniques were presented by researchers with satisfactory accuracy for last two decades. However, the recent trends of adopting distributed generators (DGs) to distribution grids are disturbing grid protection schemes by changing their technical parameters and direction of current/power flows. Additionally, the accuracy of traditional fault lactation techniques is also being affected significantly. The aim of this research paper is to review the available fault location techniques in distribution grid as well as to highlight the potential research opportunities in this field. 相似文献
998.
Md. Nooruzzaman Shogo Kawai Nguyen Thi Thanh Thuy Osanori Koyama Yutaka Katsuyama 《IEEJ Transactions on Electrical and Electronic Engineering》2012,7(3):300-307
Stackable reconfigurable optical add/drop multiplexers (S‐ROADMs) have been proposed for use in IP over coarse wavelength‐division multiplexing (CWDM) networks so as to provide capabilities of remote lightpath reconfiguration and manual ROADM reconfiguration under the best effort transmission specified by the service level agreement. The S‐ROADM can be constructed by connecting modules with different wavelengths required in the node. The experimental results clarify that the S‐ROADM can add/drop or pass through the wavelengths successfully, providing no limit to the passing‐through (PT) wavelengths, that is, ensuring the wavelength transparency in the network. The S‐ROADMs could remove congestions by adding a lightpath remotely within a recovery time with degraded SLA. The transmission break time was also within the recovery time when adding a module manually to the in‐service S‐ROADM to increase bandwidth to be provided to new users. As a result, the S‐ROADMs provide more flexible CWDM networks in terms of scalability and reconfigurability. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
999.
Rainwater: A Potential Alternative Source for Scarce Safe Drinking and Arsenic Contaminated Water in Bangladesh 总被引:2,自引:1,他引:1
Md. Manzurul Islam F. N. -F. Chou M. R. Kabir C. -H. Liaw 《Water Resources Management》2010,24(14):3987-4008
Although Bangladesh receives plenty of rainwater during its monsoon, both rural and urban areas suffer from shortages of safe drinking water during dry season. Arsenic contamination of ground water affects many rural areas, whilst some urban areas including the capital, Dhaka City, lack sufficient potable ground water to meet the demand. To cope with the problem, this research explore: the feasibility of harvesting rainwater during monsoon as a source of quality safe drinking water in Dhaka City. A questionnaire survey was conducted about potable water shortage in four slums of Dhaka City. Rainwater was collected using a non-toxic waterproof cloth as a catchment during monsoon and stored in a ferro-cement storage tank with an initial flushing device attached at the inlet of the tank. Different important physical, chemical and bacteriological parameters were tested throughout the storage period of 4 months. The efficiency of the rainwater harvesting system increased from 51% to 80% before and after installing the system. The test results were compared with the Bangladesh water quality standards. The tests have revealed slightly higher pH value (8.1 to 8.3) and enormity of color beyond the acceptable range. Although the presence of total coliform was detected after three months, traditional filtering of that stored rainwater showed a promising solution to mitigate potable water shortages in Bangladesh. 相似文献
1000.
Md.?Sirajul?IslamEmail author Toshiya?Aramaki Keisuke?Hanaki 《Water Resources Management》2005,19(4):423-445
This study investigates the water availability scenario along Tokyo Metropolitan Area (TMA) under future climatic changes.
TMA, which depends largely on the adjacent Tone river for its water supply, suffers from water shortage almost once in 2–3
yr. A methodology was developed considering integrated approach to ascertain probable impact of climatic changes on the overall
water availability along the Tone river and its impact on TMA. Historical trend in hydro-climatic characteristics of the Tone
River basin was investigated at the first place to assess the changes and interrelationships. A deterministic water balance
model was later developed, integrating natural hydrological balance as well as several water uses and river regulation effects.
The natural water balance part of the model was tested for some hypothetical climate change scenarios to observe the sensitivity
of the Tone river flow to climatic perturbations. For the worst scenario of precipitation and temperature changes, the unregulated
Tone river flow was observed to be reduced by around 20–50%, varying over different months. After considering river regulation
effects from reservoirs and diversion, the regulated flow was further analyzed based on some risk indices. Drought risk was
observed to be increased significantly for the periods between April–July. 相似文献