全文获取类型
收费全文 | 8387篇 |
免费 | 224篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 103篇 |
综合类 | 1篇 |
化学工业 | 1168篇 |
金属工艺 | 121篇 |
机械仪表 | 157篇 |
建筑科学 | 326篇 |
矿业工程 | 28篇 |
能源动力 | 233篇 |
轻工业 | 704篇 |
水利工程 | 77篇 |
石油天然气 | 18篇 |
无线电 | 851篇 |
一般工业技术 | 1317篇 |
冶金工业 | 2147篇 |
原子能技术 | 54篇 |
自动化技术 | 1309篇 |
出版年
2022年 | 61篇 |
2021年 | 108篇 |
2020年 | 81篇 |
2019年 | 126篇 |
2018年 | 131篇 |
2017年 | 125篇 |
2016年 | 148篇 |
2015年 | 113篇 |
2014年 | 179篇 |
2013年 | 407篇 |
2012年 | 316篇 |
2011年 | 420篇 |
2010年 | 284篇 |
2009年 | 276篇 |
2008年 | 352篇 |
2007年 | 328篇 |
2006年 | 283篇 |
2005年 | 251篇 |
2004年 | 211篇 |
2003年 | 185篇 |
2002年 | 184篇 |
2001年 | 171篇 |
2000年 | 133篇 |
1999年 | 159篇 |
1998年 | 520篇 |
1997年 | 352篇 |
1996年 | 232篇 |
1995年 | 215篇 |
1994年 | 190篇 |
1993年 | 174篇 |
1992年 | 111篇 |
1991年 | 83篇 |
1990年 | 109篇 |
1989年 | 106篇 |
1988年 | 85篇 |
1987年 | 84篇 |
1986年 | 80篇 |
1985年 | 98篇 |
1984年 | 91篇 |
1983年 | 75篇 |
1982年 | 59篇 |
1981年 | 56篇 |
1980年 | 62篇 |
1979年 | 72篇 |
1978年 | 58篇 |
1977年 | 87篇 |
1976年 | 166篇 |
1975年 | 62篇 |
1974年 | 40篇 |
1973年 | 43篇 |
排序方式: 共有8614条查询结果,搜索用时 187 毫秒
1.
With the emergence of distributed ledger technology (DLT), numerous practitioners and researchers have proclaimed its beneficial impact on supply chain transactions in the future. However, the vast majority of DLT initiatives are discontinued after a short period. With the full potential of DLT laying far down the road, especially managers in supply chain management (SCM) seek for short-term cost-saving effects of DLT in order to achieve long-term benefits of DLT in the future. However, the extant research has bypassed grounding long-term as well as short-term effects of DLT on supply chain transaction with empirical data. We address this shortcoming, following an abductive research approach and combining empirical data from a multiple case study design with the corresponding literature. Our study reveals that the effects of DLT on supply chain transactions are two-sided. We found six effects of DLT solutions that have a cost-reducing or cost avoidance impact on supply chain transactions. In addition, we found two effects that change the power distribution between buyers and suppliers in transactions and a single effect that reduces the dependency of supply chain transactions on third parties. While cost-reducing and avoidance as well as dependency-reducing effects are positive effects, the change in power distribution might come with disadvantages. With these findings, the paper provides the first empirical evidence of the impact of DLT on supply chain transactions, which will enable managers to improve their assessment of DLT usage in supply chains. 相似文献
2.
3.
Effects of breed and age at slaughter on degradation of muscle lipids during processing of dry‐cured hams
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Linda Storrustløkken Hanne Marie Devle Lars Erik Gangsei Carl Fredrik Naess‐Andresen Bjørg Egelandsdal Ole Alvseike Dag Ekeberg 《International Journal of Food Science & Technology》2015,50(8):1933-1943
Hams from Landrace, Duroc and Hampshire pigs slaughtered at ages 6, 7.5 and 9 months were processed to generate Norwegian Parma‐style hams. Lipid contents and the compositions of fatty acid classes (ΣSFA, ΣMUFA, ΣPUFA) within neutral lipids, phospholipids and free fatty acids were determined. Small differences in lipid degradation and composition of the classes were revealed. However, significant sensory differences related to lipids were observed. Breed was more important than age. Dry‐cured Hampshire hams gave a more intense mature odour that may be associated with higher overall lipid degradation. Unexpectedly, these hams also demonstrated high juiciness and tenderness, which could be related to the melting characteristics of the fat. Dry‐cured Duroc hams showed a higher susceptibility towards rancidity, presumably associated with preferential oxidation of n‐6 fatty acids relative to C18:1 n‐9. Dry‐cured Landrace hams showed the lowest juiciness and tenderness, likely due to their lower fat content (marbling). 相似文献
4.
Ricardo Cambraia Parreira Diana Paola Gmez‐Mendoza Itamar Couto Guedes de Jesus Rafael Pereira Lemos Anderson Kennedy Santos Cristiana Perdigo Rezende Henrique Csar Pereira Figueiredo Mauro Cunha Xavier Pinto Frank Kjeldsen Silvia Guatimosim Rodrigo Ribeiro Resende Thiago Verano‐Braga 《Proteomics. Clinical applications》2020,14(4)
5.
6.
HSDPA的度理论上最高达4.4M bit/s,但额的流量对无线接网络和空载传输容量要求有巨大影响。“3G的势头已经成为一个始终如一的主题。不过,正如我们所指出的,对3G手机的深刻领会并不总是伴随着对3G服务的持续理解。看上去高速下行包接入(HSDPA)技术可能是一个例外。它在欧洲发布,并且已经引起了人们浓厚的兴趣。看看它在亚洲的发展,我们不禁要问:它就是最终真正的3G吗?回首2002~2003年,HSDPA的部署看上去是一条漫长的道路,并且3GPP方面没有什么紧迫感,它的成员忙于应付WCDMA部署方面的复杂性。两件事的发生加速了HSDPA的部署:… 相似文献
7.
Erik Jan Marinissen 《Journal of Electronic Testing》2002,18(4-5):435-454
Modular testing is an attractive approach to testing large system ICs, especially if they are built from pre-designed reusable embedded cores. This paper describes an automated modular test development approach. The basis of this approach is that a core or module test is dissected into a test protocol and a test pattern list. A test protocol describes in detail how to apply one test pattern to the core, while abstracting from the specific test pattern stimulus and response values. Subsequent automation tasks, such as the expansion from core-level tests to system-chip-level tests and test scheduling, all work on test protocols, thereby greatly reducing the amount of compute time and data involved. Finally, an SOC-level test is assembled from the expanded and scheduled test protocols and the (so far untouched) test patterns. This paper describes and formalizes the notion of test protocols and the algorithms for test protocol expansion and scheduling. A running example is featured throughout the paper. We also elaborate on the industrial usage of the concepts described. 相似文献
8.
Antisense oligonucleotide inhibition of hepatitis C virus gene expression in transformed hepatocytes
R Hanecak V Brown-Driver MC Fox RF Azad S Furusako C Nozaki C Ford H Sasmor KP Anderson 《Canadian Metallurgical Quarterly》1996,70(8):5203-5212
Genetic and biochemical studies have provided convincing evidence that the 5' noncoding region (5' NCR) of hepatitis C virus (HCV) is highly conserved among viral isolates worldwide and that translation of HCV is directed by an internal ribosome entry site (IRES) located within the 5' NCR. We have investigated inhibition of HCV gene expression using antisense oligonucleotides complementary to the 5' NCR, translation initiation codon, and core protein coding sequences. Oligonucleotides were evaluated for activity after treatment of a human hepatocyte cell line expressing the HCV 5' NCR, core protein coding sequences, and the majority of the envelope gene (E1). More than 50 oligonucleotides were evaluated for inhibition of HCV RNA and protein expression. Two oligonucleotides, ISIS 6095, targeted to a stem-loop structure within the 5' NCR known to be important for IRES function, and ISIS 6547, targeted to sequences spanning the AUG used for initiation of HCV polyprotein translation, were found to be the most effective at inhibiting HCV gene expression. ISIS 6095 and 6547 caused concentration-dependent reductions in HCV RNA and protein levels, with 50% inhibitory concentrations of 0.1 to 0.2 microM. Reduction of RNA levels, and subsequently protein levels, by these phosphorothioate oligonucleotides was consistent with RNase H cleavage of RNA at the site of oligonucleotide hybridization. Chemically modified HCV antisense phosphodiester oligonucleotides were designed and evaluated for inhibition of core protein expression to identify oligonucleotides and HCV target sequences that do not require RNase H activity to inhibit expression. A uniformly modified 2'-methoxyethoxy phosphodiester antisense oligonucleotide complementary to the initiator AUG reduced HCV core protein levels as effectively as phosphorothioate oligonucleotide ISIS 6095 but without reducing HCV RNA levels. Results of our studies show that HCV gene expression is reduced by antisense oligonucleotides and demonstrate that it is feasible to design antisense oligonucleotide inhibitors of translation that do not require RNase H activation. The data demonstrate that chemically modified antisense oligonucleotides can be used as tools to identify important regulatory sequences and/or structures important for efficient translation of HCV. 相似文献
9.
Valproate (VPA) has been shown to interact with all the major antiepileptic drugs (AEDs) through two mechanisms of action: displacement from albumin binding sites and inhibition of drug metabolism. More recently, evidence showed that VPA inhibits the elimination of drugs metabolized by glucuronide conjugation. Lorazepam (LZP), which is primarily eliminated by conjugation with glucuronic acid, is administered concurrently with VPA both in treatment of epilepsy and in patients treated with VPA for psychiatric disorders. Therefore, a significant drug interaction is likely. We investigated such interaction both in in vitro isolated perfused rat liver (IPRL) and in normal subjects. LZP [2 mg, intravenous (i.v.) bolus] was administered to 8 normal volunteers before and after chronic dosing with VPA. In 6 of 8 subjects, VPA significantly decreased LZP plasma clearance by an average of 40% (p < 0.05) and increased LZP concentrations by decreasing formation clearance of the LZP glucuronide. In the IPRL studies, VPA also significantly decreased formation of LZP glucuronide (from 0.72 +/- 0.14 to 0.22 +/- 0.15 ml/h/kg, p < 0.05), indicating that IPRL is a useful tool for evaluation of the effect of VPA on drugs eliminated by glucuronide conjugation. 相似文献
10.