全文获取类型
收费全文 | 318412篇 |
免费 | 5765篇 |
国内免费 | 1419篇 |
专业分类
电工技术 | 5422篇 |
综合类 | 802篇 |
化学工业 | 48482篇 |
金属工艺 | 12164篇 |
机械仪表 | 9315篇 |
建筑科学 | 8027篇 |
矿业工程 | 1779篇 |
能源动力 | 8026篇 |
轻工业 | 28269篇 |
水利工程 | 3354篇 |
石油天然气 | 5939篇 |
武器工业 | 49篇 |
无线电 | 36255篇 |
一般工业技术 | 64233篇 |
冶金工业 | 56736篇 |
原子能技术 | 7795篇 |
自动化技术 | 28949篇 |
出版年
2021年 | 3242篇 |
2020年 | 2453篇 |
2019年 | 2913篇 |
2018年 | 4815篇 |
2017年 | 4950篇 |
2016年 | 5215篇 |
2015年 | 3558篇 |
2014年 | 5804篇 |
2013年 | 14592篇 |
2012年 | 8947篇 |
2011年 | 12060篇 |
2010年 | 9347篇 |
2009年 | 10551篇 |
2008年 | 10872篇 |
2007年 | 10765篇 |
2006年 | 9067篇 |
2005年 | 8414篇 |
2004年 | 8342篇 |
2003年 | 8061篇 |
2002年 | 7804篇 |
2001年 | 7760篇 |
2000年 | 7163篇 |
1999年 | 7394篇 |
1998年 | 18188篇 |
1997年 | 12869篇 |
1996年 | 9830篇 |
1995年 | 7509篇 |
1994年 | 6564篇 |
1993年 | 6584篇 |
1992年 | 4655篇 |
1991年 | 4507篇 |
1990年 | 4349篇 |
1989年 | 4288篇 |
1988年 | 3996篇 |
1987年 | 3582篇 |
1986年 | 3583篇 |
1985年 | 4019篇 |
1984年 | 3706篇 |
1983年 | 3382篇 |
1982年 | 3221篇 |
1981年 | 3256篇 |
1980年 | 3217篇 |
1979年 | 2976篇 |
1978年 | 3010篇 |
1977年 | 3325篇 |
1976年 | 4390篇 |
1975年 | 2550篇 |
1974年 | 2469篇 |
1973年 | 2496篇 |
1972年 | 2080篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Wireless Personal Communications - Chronic kidney disease (CKD) is a gradual loss of kidney function over the period of time and it is irrevocable once functionality reaches the critical state.... 相似文献
3.
Bernette Maria Oosterlaken Heiner Friedrich Gijsbertus de With 《Microscopy research and technique》2022,85(1):412-417
Transmission electron microscopy (TEM) is an important analysis technique to visualize (bio)macromolecules and their assemblies, including collagen fibers. Many protocols for TEM sample preparation of collagen involve one or more washing steps to remove excess salts from the dispersion that could hamper analysis when dried on a TEM grid. Such protocols are not standardized and washing times as well as washing solvents vary from procedure to procedure, with each research group typically having their own protocol. Here, we investigate the influence of washing with water, ethanol, but also methanol and 2-propanol, for both mineralized and unmineralized collagen samples via a protocol based on centrifugation. Washing with water maintains the hydrated collagen structure and the characteristic banding pattern can be clearly observed. Conversely, washing with ethanol results in dehydration of the fibrils, often leading to aggregation of the fibers and a less obvious banding pattern, already within 1 min of ethanol exposure. As we show, this process is fully reversible. Similar observations were made for methanol and propanol. Based on these results, a standardized washing protocol for collagenous samples is proposed. 相似文献
4.
Muniyandi Kasipandi Jagadeesan Gayathri George Blassan P. Manoharan Ashwini Lydia Nataraj Gayathri Abrahamse Heidi Thangaraj Parimelazhagan 《Food science and biotechnology》2022,31(13):1717-1728
Food Science and Biotechnology - A rich source of nutrients, figs have a number of clinically validated benefits. This study aimed to evaluate the in vitro simulated gastrointestinal digestion, and... 相似文献
5.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an... 相似文献
6.
Leibetseder Andreas Schoeffmann Klaus Keckstein Jörg Keckstein Simon 《Multimedia Tools and Applications》2022,81(5):6191-6215
Multimedia Tools and Applications - Endometriosis is a common gynecologic condition typically treated via laparoscopic surgery. Its visual versatility makes it hard to identify for non-specialized... 相似文献
7.
8.
Karimi Bayan Chang Yu-Cheng Pekola Jukka P. 《Journal of Low Temperature Physics》2022,207(3-4):220-225
We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.
相似文献9.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical... 相似文献
10.
Prof. Andrea Baier Dr. Anne Kokel Dr. William Horton Ewa Gizińska Dr. Garima Pandey Prof. Ryszard Szyszka Prof. Béla Török Prof. Marianna Török 《ChemMedChem》2021,16(12):1927-1932
A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH3)2 residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC50 values in the kinase assays. 相似文献