全文获取类型
收费全文 | 29776篇 |
免费 | 1587篇 |
国内免费 | 130篇 |
专业分类
电工技术 | 477篇 |
综合类 | 238篇 |
化学工业 | 5033篇 |
金属工艺 | 805篇 |
机械仪表 | 676篇 |
建筑科学 | 846篇 |
矿业工程 | 147篇 |
能源动力 | 481篇 |
轻工业 | 4073篇 |
水利工程 | 212篇 |
石油天然气 | 136篇 |
武器工业 | 10篇 |
无线电 | 1590篇 |
一般工业技术 | 5466篇 |
冶金工业 | 7560篇 |
原子能技术 | 171篇 |
自动化技术 | 3572篇 |
出版年
2023年 | 322篇 |
2022年 | 278篇 |
2021年 | 637篇 |
2020年 | 516篇 |
2019年 | 436篇 |
2018年 | 904篇 |
2017年 | 821篇 |
2016年 | 924篇 |
2015年 | 808篇 |
2014年 | 963篇 |
2013年 | 1792篇 |
2012年 | 1361篇 |
2011年 | 1368篇 |
2010年 | 1171篇 |
2009年 | 1111篇 |
2008年 | 1247篇 |
2007年 | 1201篇 |
2006年 | 837篇 |
2005年 | 689篇 |
2004年 | 508篇 |
2003年 | 473篇 |
2002年 | 420篇 |
2001年 | 351篇 |
2000年 | 340篇 |
1999年 | 463篇 |
1998年 | 2364篇 |
1997年 | 1425篇 |
1996年 | 994篇 |
1995年 | 600篇 |
1994年 | 497篇 |
1993年 | 441篇 |
1992年 | 185篇 |
1991年 | 195篇 |
1990年 | 159篇 |
1989年 | 168篇 |
1988年 | 159篇 |
1987年 | 165篇 |
1986年 | 151篇 |
1985年 | 227篇 |
1984年 | 193篇 |
1983年 | 175篇 |
1982年 | 135篇 |
1981年 | 188篇 |
1980年 | 180篇 |
1979年 | 127篇 |
1978年 | 107篇 |
1977年 | 226篇 |
1976年 | 489篇 |
1975年 | 91篇 |
1973年 | 113篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Iryna Smokovych Manja Krüger Michael Scheffler 《Journal of the European Ceramic Society》2019,39(13):3634-3642
Silica-based coating systems were developed using polymer derived ceramics (PDCs) technology. Ceramic composites on the base of a SiO2 and SiNO matrix and homogeneously distributed Mo5SiB2, SiB6, Si and B fillers were manufactured. The coating systems have low porosity and provide a high oxidation resistance up to 100 h at 800 °C and 1100 °C in air. The influence of temperature and atmosphere of pyrolysis on the polymer precursor, the volume fraction of filler materials on the chemical composition of compacts as well as their high-temperature oxidation protection was investigated. 相似文献
32.
33.
34.
35.
Bengü Ergüden 《Yeast (Chichester, England)》2019,36(2):99-105
The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (S my2, E ap1, S cp160, A sc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA. 相似文献
36.
37.
Freddy A. Bernal Dr. Marcel Kaiser Prof. Dr. Bernhard Wünsch Prof. Dr. Thomas J. Schmidt 《ChemMedChem》2020,15(1):68-78
Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model. 相似文献
38.
I. Ansia H.H. Stein C. Brøkner C.A. Hayes J.K. Drackley 《Journal of dairy science》2021,104(3):2979-2995
The aims of this experiment were (1) to compare the effects of a soybean meal with an enzymatic treatment (ESBM) to reduce the concentration of antinutritional factors versus a standard soybean meal (SBM) on foregut and small intestine digestion in weaned dairy calves and (2) to estimate the endogenous losses of crude protein (CP) in the small intestine. Our hypothesis was that a diet containing ESBM instead of SBM would improve ruminal and small intestine digestion and absorption of nutrients. A T-cannula was placed in the duodenum, and a second T-cannula was installed in the distal ileum of 12 Holstein calves at approximately 3 wk of age. Calves were weaned on d 42, and on d 50 they were assigned randomly to a quadruplicated 3 × 3 Latin square with 10-d periods. Digesta samples were collected on d 7 and 8 from the ileum and d 9 and 10 from the duodenum. The diets were fed for ad libitum intake and consisted of a calf starter (CS) of 20% CP with SBM as the main source of protein (CTRL), and an isonitrogenous CS with an ESBM instead of SBM (ENZT). A third diet with a low content of CP (10%) and no soy protein was fed to estimate endogenous N losses and digestibilities of test ingredients. Flows and digestibilities of nutrients were compared between CTRL and ENZT and their test ingredients (SBM vs. ESBM, respectively). Duodenal net flows of CP and total AA as well as ruminal microbial protein synthesis per kilogram of digested CP were greater, and flow of nonprotein N and CP true (corrected by endogenous and microbial flows) foregut digestibility were lower with ENZT than CTRL. The apparent small intestine digestibilities of CP and total AA were greater for ESBM than SBM, but there were no differences between the CTRL and ENZT diets. We observed no differences in digestibilities at the duodenum or ileum of starch or NDF, but true small intestine digestibilities of CP and all AA were greater with ENZT than CTRL. Total endogenous protein losses in the small intestine estimated from calves fed the low-CP with no soy protein diet were 37 ± 1.5 g of CP and 29 ± 1.4 g of AA/kg of DMI. These values may be considered the basal endogenous losses as they are similar to values obtained with the regression method, which estimates N losses when dietary N is null. Our results indicated that the inclusion of an ESBM improved the efficiency of ruminal microbial protein synthesis per digested kilogram of organic matter and CP, and increased CP and AA absorption in the small intestine despite a greater proportion of undigested dietary protein entering the duodenum. 相似文献
39.
40.
Özge Seçmeler Özlem Güçlü Üstündağ 《International Journal of Food Science & Technology》2019,54(5):1609-1616
The partitioning of predominant lipophilic olive bioactives (squalene, β-sitosterol and α-tocopherol) in olive oil processing was studied for the first time using common integrated olive milling plant. 7% of the oil and 5% of the squalene present in the olives was lost in the last pomace. β-sitosterol and α-tocopherol, which are mainly concentrated in the seed of the olive fruit, was recovered in virgin olive oil to a lesser extent (66%, 67%) while 10% were lost in last pomace. Thus, the loss of β-sitosterol and α-tocopherol was higher than that of squalene and oil, due to nonrecovered bound forms. 19% of the α-tocopherol and 21% of the β-sitosterol loss was unaccounted for, which can be attributed to degradation of α-tocopherol and incomplete recovery of sterols from the olive and pomace matrices. This study provides a basis for process development studies. 相似文献