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   868篇
  免费   24篇
  国内免费   6篇
电工技术   41篇
化学工业   139篇
金属工艺   32篇
机械仪表   23篇
建筑科学   16篇
能源动力   25篇
轻工业   85篇
水利工程   4篇
无线电   89篇
一般工业技术   180篇
冶金工业   203篇
原子能技术   26篇
自动化技术   35篇
  2023年   8篇
  2022年   4篇
  2021年   12篇
  2020年   12篇
  2019年   5篇
  2018年   8篇
  2017年   16篇
  2016年   12篇
  2015年   12篇
  2014年   20篇
  2013年   41篇
  2012年   33篇
  2011年   44篇
  2010年   30篇
  2009年   31篇
  2008年   29篇
  2007年   26篇
  2006年   17篇
  2005年   32篇
  2004年   32篇
  2003年   26篇
  2002年   31篇
  2001年   23篇
  2000年   27篇
  1999年   13篇
  1998年   89篇
  1997年   54篇
  1996年   30篇
  1995年   22篇
  1994年   19篇
  1993年   15篇
  1992年   5篇
  1991年   12篇
  1990年   9篇
  1989年   15篇
  1988年   7篇
  1987年   5篇
  1986年   4篇
  1985年   4篇
  1984年   4篇
  1983年   3篇
  1982年   12篇
  1981年   5篇
  1980年   3篇
  1979年   7篇
  1977年   5篇
  1976年   11篇
  1974年   2篇
  1973年   3篇
  1972年   2篇
排序方式: 共有898条查询结果,搜索用时 31 毫秒
841.
This paper describes the performance of NASDA's various space solar cells by comparing flight data and ground test data. We first present the flight data from the Solar Cell Monitor on Engineering Test Satellite-VI. We then describe the ground irradiation tests of solar cells performed in collaboration with the Japan Atomic Energy Research Institute. Then discuss the radiation effects on solar cells, and present other flight data of solar cells and optical data of the coverglass from other satellites in addition. Finally, we describe the future plan to obtain flight data on various solar cells.  相似文献   
842.
The Gmicro/200, a microprocessor that has been developed as part of Japan's TRON (The Real-Time Operating Nucleus) project, is described. This microprogram-based processor with six-state pipeline, 730000 transistors and on-chip caches will serve in an engineering workstation or a high-speed graphics accelerator system. The authors discuss features of the instruction set; memory management; handling of exceptions, interrupts and traps; and the implementation of the Gmicro/200  相似文献   
843.
844.
The mixture of a Zr-Al metallo-organic compound and Al2O3 powder yields dense ZrO2-Al2O3 composite ceramics. The fraction of the tetragonal ZrO2 phase in as-sintered ZrO2-Al2O3 ceramics is almost 100% and the ZrO2 grains at about 500 nm in diameter are dispersed in the matrix. The ceramics have high fracture toughness and bending strength.  相似文献   
845.
A conductor temperature monitoring system using the current method was developed to estimate conductor temperatures at joints of extra-high-voltage (EHV) underground power transmission XLPE cables in real time. The validity of the software and hardware was confirmed by measurements on an extrusion molded joint (EMJ) of a 275 kV 1×2500 mm2 aluminum-sheathed XLPE cable. The mean circumferential jacket surface temperature over the EMJ, where the cross section was larger than that at the cable portion, was measured by a line thermosensor using thermocouples or a distributed temperature sensor using an optical fiber. The conductor temperature in the cable joint was estimated by numerically solving simultaneous differential equations with 31 unknowns. A system which allows measurement of the cable conductor current at insulation joints of installed lines was also developed  相似文献   
846.
The human PWP2 gene is the human homologue of the yeast periodic tryptophan protein 2 (PWP2) gene and is a member of the gene family that contains tryptophan-aspartate (WD) repeats. Genomic sequencing revealed that the human PWP2 gene consists of 21 exons spanning approximately 24 kb and locates just between the two genes EHOC-1 and KNP-I and distal to a NotI site of LJ104 (D21S1460) on chromosome 21q22.3. Analysis of the 5'-flanking DNA sequence revealed that the upstream region of the PWP2 gene is associated with a CpG island containing the NotI site of LJ104. Since PWP2 is considered to be a candidate for genetic disorders mapped in the 21q22.3 region, the information including nucleotide sequence and genomic organization of the PWP2 gene should be invaluable for the mutation analysis of the corresponding genetic disorders.  相似文献   
847.
The patient was a 68-year-old male, who underwent total gastrectomy for giant leiomyosarcoma of the stomach and then had multiple hepatic metastases one year and six months later. Thus, transarterial hepatic chemo-embolization therapy with Lipiodol, adriamycin and gelfoam was given. Moreover, using a reservoir catheter and infusion arterial port, intermittent arterial infusion therapy with adriamycin, cyclophosphamide, and vincristine was attempted. In the metastasis lesion where there were rich blood vessels, Lipiodol was accumulated and the tumor was reduced on abdominal CT. The result indicated the efficacy of this treatment.  相似文献   
848.
The effect of activating the renin-angiotensin system on the metabolism of angiotensins (ANGs) in normotensive human plasma was investigated. In normotensive supine human plasma, four peptides with in vitro angiotensin I-converting enzyme (ACE) inhibitory activity which correspond to the sequence of ANG (3-8), ANG (4-8), ANG (5-8), and ANG (3-4) existed at a concentration of > 39 fmol/ml of plasma. When activating the renin activity by keeping upright in posture for 60 min, ANG II and the four peptides significantly increased as compared with the levels in the supine posture, except for ANG I. In particular, Val-Tyr corresponding to ANG (3-4) in the upright posture was about 4-fold more than the value in the supine posture, and was predominantly present (447 fmol/ml of plasma) as well as ANG I. As a result of in vitro degradation tests on ANGs, ANG (3-4) was produced from ANG I, and not from ANG II, III or (3-8), during the 30-min incubation.  相似文献   
849.
The initiation of DNA synthesis is an important cell cycle event that defines the beginning of S phase. This critical event involves the participation of proteins whose functions are regulated by cyclin dependent protein kinases (Cdks). The Mcm2-7 proteins are a family of six conserved proteins that are essential for the initiation of DNA synthesis in all eukaryotes. In Saccharomyces cerevisiae, members of the Mcm2-7 family undergo cell cycle-specific phosphorylation. Phosphorylation of Mcm proteins at the beginning of S phase coincides with the removal of these proteins from chromatin and the onset of DNA synthesis. In this study, we identified DBF4, which encodes the regulatory subunit of a Cdk-like protein kinase Cdc7-Dbf4, in a screen for second site suppressors of mcm2-1. The dbf4 suppressor mutation restores competence to initiate DNA synthesis to the mcm2-1 mutant. Cdc7-Dbf4 interacts physically with Mcm2 and phosphorylates Mcm2 and three other members of the Mcm2-7 family in vitro. Blocking the kinase activity of Cdc7-Dbf4 at the G1-to-S phase transition also blocks the phosphorylation of Mcm2 at this defined point of the cell cycle. Taken together, our data suggest that phosphorylation of Mcm2 and probably other members of the Mcm2-7 proteins by Cdc7-Dbf4 at the G1-to-S phase transition is a critical step in the initiation of DNA synthesis at replication origins.  相似文献   
850.
To reduce renal cyst size in autosomal dominant polycystic kidney disease (ADPKD), minocycline hydrochloride solution was instilled into the enlarged cysts in three ADPKD patients. In one patient with reduced renal function, such sclerotherapy apparently diminished cyst size, but without apparent improving effect on renal function at 7 months of follow-up. The second patient, who needed the replacement therapy on admission, had been free from hemodialysis over 4 months after the therapy. Persistent flank pain disappeared in both patients. In the third patient with normal renal function, sclerotherapy was done to get a better control of hypertension. Initially blood pressure decreased, but it returned up to the pre-therapy level irrespective of definite reduction of the enlarged cysts at 8 months of follow-up. The therapy with minocycline hydrochloride did not appear harmful, and may be helpful in the management of ADPKD.  相似文献   
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