全文获取类型
收费全文 | 251845篇 |
免费 | 23644篇 |
国内免费 | 11150篇 |
专业分类
电工技术 | 14441篇 |
技术理论 | 32篇 |
综合类 | 24325篇 |
化学工业 | 40156篇 |
金属工艺 | 10385篇 |
机械仪表 | 11944篇 |
建筑科学 | 32735篇 |
矿业工程 | 13414篇 |
能源动力 | 8990篇 |
轻工业 | 20449篇 |
水利工程 | 11230篇 |
石油天然气 | 13971篇 |
武器工业 | 3577篇 |
无线电 | 17528篇 |
一般工业技术 | 21370篇 |
冶金工业 | 13066篇 |
原子能技术 | 1896篇 |
自动化技术 | 27130篇 |
出版年
2024年 | 1176篇 |
2023年 | 3708篇 |
2022年 | 6473篇 |
2021年 | 8550篇 |
2020年 | 8499篇 |
2019年 | 6617篇 |
2018年 | 6126篇 |
2017年 | 7706篇 |
2016年 | 9114篇 |
2015年 | 9626篇 |
2014年 | 17045篇 |
2013年 | 15224篇 |
2012年 | 18014篇 |
2011年 | 19729篇 |
2010年 | 14490篇 |
2009年 | 14825篇 |
2008年 | 13375篇 |
2007年 | 16448篇 |
2006年 | 14994篇 |
2005年 | 13069篇 |
2004年 | 10896篇 |
2003年 | 9487篇 |
2002年 | 7734篇 |
2001年 | 6440篇 |
2000年 | 5483篇 |
1999年 | 4352篇 |
1998年 | 3095篇 |
1997年 | 2685篇 |
1996年 | 2236篇 |
1995年 | 1881篇 |
1994年 | 1591篇 |
1993年 | 1150篇 |
1992年 | 936篇 |
1991年 | 696篇 |
1990年 | 586篇 |
1989年 | 530篇 |
1988年 | 322篇 |
1987年 | 270篇 |
1986年 | 235篇 |
1985年 | 268篇 |
1984年 | 203篇 |
1983年 | 156篇 |
1982年 | 103篇 |
1981年 | 95篇 |
1980年 | 103篇 |
1979年 | 44篇 |
1978年 | 26篇 |
1977年 | 23篇 |
1959年 | 26篇 |
1951年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
911.
Marleen Julia Meyer Simon Falk Sarah Rmer Clarissa Prinzinger Sabine Tacke Joachim Geyer Stefan Simm Mladen Vassilev Tzvetkov 《International journal of molecular sciences》2022,23(9)
OCT1 and OCT2 are polyspecific membrane transporters that are involved in hepatic and renal drug clearance in humans and mice. In this study, we cloned dog OCT1 and OCT2 and compared their function to the human and mouse orthologs. We used liver and kidney RNA to clone dog OCT1 and OCT2. The cloned and the publicly available RNA-Seq sequences differed from the annotated exon-intron structure of OCT1 in the dog genome CanFam3.1. An additional exon between exons 2 and 3 was identified and confirmed by sequencing in six additional dog breeds. Next, dog OCT1 and OCT2 were stably overexpressed in HEK293 cells and the transport kinetics of five drugs were analyzed. We observed strong differences in the transport kinetics between dog and human orthologs. Dog OCT1 transported fenoterol with 12.9-fold higher capacity but 14.3-fold lower affinity (higher KM) than human OCT1. Human OCT1 transported ipratropium with 5.2-fold higher capacity but 8.4-fold lower affinity than dog OCT1. Compared to human OCT2, dog OCT2 showed 10-fold lower transport of fenoterol and butylscopolamine. In conclusion, the functional characterization of dog OCT1 and OCT2 reported here may have implications when using dogs as pre-clinical models as well as for drug therapy in dogs. 相似文献
912.
Mariantonia Logozzi Rossella Di Raimo Davide Mizzoni Stefano Fais 《International journal of molecular sciences》2022,23(9)
Research in science and medicine is witnessing a massive increases in literature concerning extracellular vesicles (EVs). From a morphological point of view, EVs include extracellular vesicles of a micro and nano sizes. However, this simplistic classification does not consider both the source of EVs, including the cells and the species from which Evs are obtained, and the microenvironmental condition during EV production. These two factors are of crucial importance for the potential use of Evs as therapeutic agents. In fact, the choice of the most suitable Evs for drug delivery remains an open debate, inasmuch as the use of Evs of human origin may have at least two major problems: (i) autologous Evs from a patient may deliver dangerous molecules; and (ii) the production of EVs is also limited to cell factory conditions for large-scale industrial use. Recent literature, while limited to only a few papers, when compared to the papers on the use of human EVs, suggests that plant-derived nanovesicles (PDNV) may represent a valuable tool for extensive use in health care. 相似文献
913.
914.
915.
916.
Alessandro Di Minno Monica Gelzo Marianna Caterino Michele Costanzo Margherita Ruoppolo Giuseppe Castaldo 《International journal of molecular sciences》2022,23(9)
Metabolomics helps identify metabolites to characterize/refine perturbations of biological pathways in living organisms. Pre-analytical, analytical, and post-analytical limitations that have hampered a wide implementation of metabolomics have been addressed. Several potential biomarkers originating from current targeted metabolomics-based approaches have been discovered. Precision medicine argues for algorithms to classify individuals based on susceptibility to disease, and/or by response to specific treatments. It also argues for a prevention-based health system. Because of its ability to explore gene–environment interactions, metabolomics is expected to be critical to personalize diagnosis and treatment. Stringent guidelines have been applied from the very beginning to design studies to acquire the information currently employed in precision medicine and precision prevention approaches. Large, prospective, expensive and time-consuming studies are now mandatory to validate old, and discover new, metabolomics-based biomarkers with high chances of translation into precision medicine. Metabolites from studies on saliva, sweat, breath, semen, feces, amniotic, cerebrospinal, and broncho-alveolar fluid are predicted to be needed to refine information from plasma and serum metabolome. In addition, a multi-omics data analysis system is predicted to be needed for omics-based precision medicine approaches. Omics-based approaches for the progress of precision medicine and prevention are expected to raise ethical issues. 相似文献
917.
918.
研究了低合金钢板在尖头弹冲击条件下的侵彻过程,讨论了应力条件和材料冶金质量对损伤和断裂的影响。结果表明,在侵彻过程前期靶材主要表现为三向压应力下的塑性流动;中期,靶材挤压流动,靶材内部的流速差造成剪切变形,并导致沿轧制偏析带的开裂;后期,靶材在剧烈剪切作用下剪切变形、局部失稳、形成剪切带和沿剪切带的开裂或撕裂。断裂按微孔聚集型机制进行。通常所谓花瓣型开裂实质上就是上述在切应力作用下的剪切撕裂。 相似文献
919.
鲜红斑痣光动力治疗数学模型及临床验证 总被引:7,自引:1,他引:7
为了研究光动力治疗(PDT)中各个因素作用的规律,帮助临床采取有效的治疗方案,针对鲜红斑痣(PWS)组织特性,将光动力治疗中组织光分布、单线态氧产生、光敏剂漂白过程和光敏剂扩散过程结合起来,建立适合于光动力治疗鲜红斑痣病变的系统模型。利用建立的模型,对临床中出现的第二光斑治疗效果差的问题进行仿真研究,发现影响其治疗效果的因素,并通过仿真实验提出改进其治疗效果的新方案。通过临床实验,证明了新方案的有效性和模型的有效性。研究结果说明,针对特定的病例条件建立仿真模型,通过仿真实验可以为临床和理论研究提供一种有效的分析方法。 相似文献
920.