首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   641901篇
  免费   8581篇
  国内免费   1871篇
电工技术   11324篇
综合类   2837篇
化学工业   93140篇
金属工艺   28382篇
机械仪表   22107篇
建筑科学   15363篇
矿业工程   3319篇
能源动力   15893篇
轻工业   50439篇
水利工程   6955篇
石油天然气   10593篇
武器工业   37篇
无线电   72063篇
一般工业技术   126915篇
冶金工业   109253篇
原子能技术   11399篇
自动化技术   72334篇
  2022年   3166篇
  2021年   4900篇
  2020年   3483篇
  2019年   4560篇
  2018年   25169篇
  2017年   24520篇
  2016年   19232篇
  2015年   6401篇
  2014年   9483篇
  2013年   24262篇
  2012年   18777篇
  2011年   33271篇
  2010年   27780篇
  2009年   26998篇
  2008年   27916篇
  2007年   29824篇
  2006年   15654篇
  2005年   17692篇
  2004年   15843篇
  2003年   15474篇
  2002年   13537篇
  2001年   12955篇
  2000年   12110篇
  1999年   12657篇
  1998年   32856篇
  1997年   22920篇
  1996年   17491篇
  1995年   13050篇
  1994年   11316篇
  1993年   11003篇
  1992年   7929篇
  1991年   7459篇
  1990年   7261篇
  1989年   7013篇
  1988年   6476篇
  1987年   5766篇
  1986年   5656篇
  1985年   6266篇
  1984年   5900篇
  1983年   5170篇
  1982年   4900篇
  1981年   4967篇
  1980年   4705篇
  1979年   4609篇
  1978年   4408篇
  1977年   5335篇
  1976年   6971篇
  1975年   3796篇
  1974年   3550篇
  1973年   3665篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies.  相似文献   
76.
Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein.  相似文献   
77.
Vertical arrays of nanostructures (NSs) are emerging as promising platforms for probing and manipulating live mammalian cells. The broad range of applications requires different types of interfaces, but cell settling on NS arrays is not yet fully controlled and understood. Cells are both seen to deform completely into NS arrays and to stay suspended like tiny fakirs, which have hitherto been explained with differences in NS spacing or density. Here, a better understanding of this phenomenon is provided by using a model that takes into account the extreme membrane deformation needed for a cell to settle into a NS array. It is shown that, in addition to the NS density, cell settling depends strongly on the dimensions of the single NS, and that the settling can be predicted for a given NS array geometry. The predictive power of the model is confirmed by experiments and good agreement with cases from the literature. Furthermore, the influence of cell‐related parameters is evaluated theoretically and a generic method of tuning cell settling through surface coating is demonstrated experimentally. These findings allow a more rational design of NS arrays for the numerous exciting biological applications where the mode of cell settling is crucial.  相似文献   
78.
79.
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号