全文获取类型
收费全文 | 2063篇 |
免费 | 68篇 |
学科分类
工业技术 | 2131篇 |
出版年
2023年 | 19篇 |
2022年 | 10篇 |
2021年 | 55篇 |
2020年 | 38篇 |
2019年 | 31篇 |
2018年 | 39篇 |
2017年 | 38篇 |
2016年 | 39篇 |
2015年 | 34篇 |
2014年 | 50篇 |
2013年 | 115篇 |
2012年 | 107篇 |
2011年 | 140篇 |
2010年 | 100篇 |
2009年 | 100篇 |
2008年 | 122篇 |
2007年 | 109篇 |
2006年 | 108篇 |
2005年 | 91篇 |
2004年 | 83篇 |
2003年 | 69篇 |
2002年 | 72篇 |
2001年 | 42篇 |
2000年 | 45篇 |
1999年 | 35篇 |
1998年 | 68篇 |
1997年 | 50篇 |
1996年 | 46篇 |
1995年 | 38篇 |
1994年 | 33篇 |
1993年 | 30篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1971年 | 4篇 |
1956年 | 3篇 |
排序方式: 共有2131条查询结果,搜索用时 31 毫秒
1.
Kathleen T. Lauser Amy L. Rueter Michelle A. Calabrese 《American Institute of Chemical Engineers》2022,68(12):e17850
While protein medications are promising for treatment of cancer and autoimmune diseases, challenges persist in terms of development and injection stability of high-concentration formulations. Here, the extensional flow properties of protein-excipient solutions are examined via dripping-onto-substrate extensional rheology, using a model ovalbumin (OVA) protein and biocompatible excipients polysorbate 20 (PS20) and 80 (PS80). Despite similar PS structures, differences in extensional flow are observed based on PS identity in two regimes: at moderate total concentrations where surface tension differences drive changes in extensional flow behavior, and at small PS:OVA ratios, which impact the onset of weakly elastic flow behavior. Undesirable elasticity is observed in ultra-concentrated formulations, independent of PS identity; higher PS contents are required to observe these effects than in analogous polymeric excipient solutions. These studies reveal novel extensional flow behaviors in protein-excipient solutions, and provide a straightforward methodology for assessing the extensional flow stability of new protein-excipient formulations. 相似文献
2.
Minds and Machines - To address the rising concern that algorithmic decision-making may reinforce discriminatory biases, researchers have proposed many notions of fairness and corresponding... 相似文献
3.
Evangelos Pavlakis Michelle Neumann Thorsten Stiewe 《International journal of molecular sciences》2020,21(24)
Tumor progression to a metastatic and ultimately lethal stage relies on a tumor-supporting microenvironment that is generated by reciprocal communication between tumor and stromal host cells. The tumor–stroma crosstalk is instructed by the genetic alterations of the tumor cells—the most frequent being mutations in the gene Tumor protein p53 (TP53) that are clinically correlated with metastasis, drug resistance and poor patient survival. The crucial mediators of tumor–stroma communication are tumor-derived extracellular vesicles (EVs), in particular exosomes, which operate both locally within the primary tumor and in distant organs, at pre-metastatic niches as the future sites of metastasis. Here, we review how wild-type and mutant p53 proteins control the secretion, size, and especially the RNA and protein cargo of tumor-derived EVs. We highlight how EVs extend the cell-autonomous tumor suppressive activity of wild-type p53 into the tumor microenvironment (TME), and how mutant p53 proteins switch EVs into oncogenic messengers that reprogram tumor–host communication within the entire organism so as to promote metastatic tumor cell dissemination. 相似文献
4.
To enhance the understanding of the behavior and effects of the precipitation of MnO2 particles in the subsurface generated during in situ chemical oxidation (ISCO) using permanganate, laboratory batch experiments were completed to examine the influence that varied reaction matrix conditions have on the generation and properties of manganese oxides. The conditions examined include organic material type and concentration, permanganate concentration, pH, and the presence of calcium (as a representative divalent cation) in solution. Experimental studies included: (1) spectrophotometric examination of permanganate depletion and manganese oxides generation over time during reactions with trichloroethene; (2) scanning electron microscopy analyses of manganese particle morphology; (3) particle size distribution (filtration) characterization studies; and (4) optical particle sizing and numeration studies. Bench-scale, batch experiments were conducted to focus on fundamental chemical properties affecting particle development under varied potential environmental conditions. The amount of manganese oxides particles that develop, grow, and potentially settle as a result of permanganate ISCO of organic contaminants is a function of the particle size and concentration, the time allowed for particle development, and the impact of matrix conditions on the ability of particles to agglomerate. 相似文献
5.
6.
7.
IG Sumner A Vaughan R Eisenthal RW Pickersgill AJ Owen PW Goodenough 《Canadian Metallurgical Quarterly》1993,1164(3):243-251
Papaya proteinase omega (pp omega) has been purified from dried latex both by immunoaffinity and traditional methods. Kinetic analysis revealed that (1), the pp omega-catalysed hydrolysis of N-benzoyl-L-arginine p-nitroanilide (BApNA) has a lower specificity (kcat/Km) than the same reaction catalysed by papain; (2), the pp omega-catalysed hydrolysis of a tripeptide substrate having phenylalanine at the second position (S2-site) showed a more similar specificity to that catalysed by papain; (3), the significant difference between the two enzymes is that steady state kinetics with both L-BApNA and a tripeptide enables the identification in pp omega of other ionizations affecting binding. The active sites of papain and pp omega can therefore be distinguished by pH-dependence of kcat/Km. 相似文献
8.
9.
Michelle Abraham 《电子产品世界》2008,(7)
数字视频编码和解码芯片目前需求量很大.在未来几年里,这种芯片的市场将更加强劲地增长.推动这个市场增长的因素有三个:一个是全球范围的从模拟电视向数字电视的过渡,这种过渡将刺激数字接收机和基础设施设备的需求;另一个因素是手机、便携式播放机和汽车内的移动视频功能日益流行;第三个因素是数字视频标准的持续发展将推动对提供高性能芯片的新需求. 相似文献
10.
This report summarizes the panel held at the 109th Annual Convention, American Psychological Association, August 26, 2001, San Francisco. The chair was William Glover and the speakers were Samuel Gerson, Karen Maroda, and Andre Patsalides. The invited symposium was directed at discussing different perspectives related to the presence of desire in the analytic process. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献