全文获取类型
收费全文 | 1067篇 |
免费 | 30篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 75篇 |
综合类 | 2篇 |
化学工业 | 316篇 |
金属工艺 | 32篇 |
机械仪表 | 24篇 |
建筑科学 | 24篇 |
能源动力 | 54篇 |
轻工业 | 103篇 |
石油天然气 | 1篇 |
无线电 | 49篇 |
一般工业技术 | 192篇 |
冶金工业 | 90篇 |
原子能技术 | 49篇 |
自动化技术 | 89篇 |
出版年
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 31篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 18篇 |
2016年 | 34篇 |
2015年 | 21篇 |
2014年 | 37篇 |
2013年 | 74篇 |
2012年 | 54篇 |
2011年 | 74篇 |
2010年 | 47篇 |
2009年 | 45篇 |
2008年 | 53篇 |
2007年 | 52篇 |
2006年 | 57篇 |
2005年 | 36篇 |
2004年 | 38篇 |
2003年 | 30篇 |
2002年 | 18篇 |
2001年 | 18篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 20篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1966年 | 1篇 |
1964年 | 2篇 |
排序方式: 共有1100条查询结果,搜索用时 15 毫秒
101.
102.
A human RNA helicase gene, DBP1, was cloned by PCR methodsusing degenerate oligonucleotide primers corresponding to highly conserved motifs among known members of the DEAH-box protein family. The full-length DBP1 contains 3028 nucleotides and codes for a protein of 813 amino acids with a calculated mol. wt. of 92723 daltons. The predicted amino acid sequence shares extensive homology with Prp2, Prp16, and Prp22 proteins, which are required to splice mRNA precursors in budding yeast. The protein encoded by DBP1 has RGD, RD, and HS(A/T) repeat motifs close to the N-terminus. Southern blot analysis suggested the presence of a homologue of the DBP1 genes in other species, and Northern blot analysis showed that DBP1 is expressed ubiquitously in various human organs investigated. The DBP1 gene was found to be on chromosome 4p15.3 and encodes a putative nuclear ATP-dependent RNA helicase. 相似文献
103.
Osamu Nakagawa Haruo Shimamoto Tetsuya Ueda Kou Shimomura Tsutomu Hata Toru Tachikawa Jiro Fukushima Toshinobu Banjo Isamu Yamamoto 《Journal of Electronic Materials》1989,18(5):633-643
As electronic devices become more highly integrated, the demand for small, high pin count packages has been increasing. We
have developed two new types of IC packages in response to this demand. One is an ultra thin small outline package (TSOP)
which has been reduced in size from the standard SOP and the other, which uses Tape Automated Bonding (TAB) technology, is
a super thin, high pin count TAB in cap (T.I.C.) package. In this paper, we present these packages and their features along
with the technologies used to improve package reliability and TAB. Thin packages are vulnerable to high humidity exposure,
especially after heat shock.1 The following items were therefore investigated in order to improve humidity resistance: (1)
The molding compound thermal stress, (2) Water absorption into the molding compound and its effect on package cracking during
solder dipping, (3) Chip attach pad area and its affect on package cracking, (4) Adhesion between molding resin and chip attach
pad and its affect on humidity resistance. With the improvements made as a result of these investigations, the reliability
of the new thin packages is similar to that of the standard thicker plastic packages. 相似文献
104.
105.
A method for the stereospecific analysis of triacyl-sn-glycerols by high-performance liquid chromatography (HPLC) on a chiral column is described. Triacyl-sn-glycerols were partially degraded with ethyl magnesium bromide, and the monoacylglycerols produced were separated as 1- and
2-monoacylglycerol fractions by thin-layer chromatography on boric acid-impregnated silica gel plates. The 1-monoacylglycerols
were resolved intosn-1 andsn-3 monoacylglycerol fractions by HPLC on a chiral column (Sumichiral OA-4100) after derivatization with 3,5-dinitrophenyl
isocyanate. Fatty acid methyl esters obtained from the original triacyl-sn-glycerols, 1- and 2-monoacylglycerol fractions, andsn-1 andsn-3 monoacylglycerol fractions were analyzed by gas chromatography on open-tubular columns. Stereospecific acyl distributions
in triacyl-sn-glycerols were calculated from the data. The acyl distributions of several oils were obtained. The method is rapid, simple
and gave reproducible results. 相似文献
106.
H Kaneko KO Orii E Matsui N Shimozawa T Fukao T Matsumoto A Shimamoto Y Furuichi S Hayakawa K Kasahara N Kondo 《Canadian Metallurgical Quarterly》1997,240(2):348-353
Bloom syndrome (BS) is a rare genetic disorder characterized by small body size, sun sensitivity, immunodeficiency and a high predisposition to various types of cancer. BLM was identified as the causative gene for BS, and BLM protein is homologous to DNA helicase. There are two putative nuclear localization signals (NLSs) within amino acid residues 1334-1349 in the C-terminus of the BLM protein, which has the distinctive structure of two basic residue arms separated by a spacer. The entire coding or deleted BLM sequences of various sizes were ligated into an enhanced green fluorescent protein (EGFP) vector and transfected into HeLa cells. The EGFP vector harboring the entire BLM coding sequence was transported to the nucleus. The BLM protein truncated at 1341 amino acid, containing an intact helicase domain and only one proximal arm, was not transported to the nucleus. The BLM protein truncated at 1357 amino acid, containing an intact helicase domain and two arms, was transported to the nucleus. The EGFP vector harboring DNA fragments encoding a protein having only the distal arms of basic amino acids in the C-terminus was also transported to the nucleus. The truncated BLM proteins corresponding to previously reported mutated BLM proteins were retained in the cytoplasm or both the cytoplasm and the nucleus as was the EGFP vector with no insert. These results show that the BLM protein translocates into the nucleus and that the distal arm of the bipartite basic residues in the C-terminus of the BLM protein is essential for targeting the nucleus. 相似文献
107.
Akihiko Yamaguchi Kosuke Kurokawa Toru Uno Masaharu Takahashi 《Solar Energy Materials & Solar Cells》2003,75(3-4):679-686
In this paper, the authors investigated the reflection and absorption characteristics of a general photovoltaic (PV) module. As a result, the electromagnetic waves could be attenuated only 6 dB in typical PV module. However, if the PV module is installed in the outer wall of buildings, electromagnetic interference is caused by the surroundings. To reduce this electromagnetic interference, the authors suggested a method to absorb electromagnetic wave using multiple PV modules that have deference impedance, and simulation was performed. As a result, it was confirmed that using a typical PV module and the PV module including electronic device, the reflection waves of those PV modules could be attenuated up to 12 dB. 相似文献
108.
An experimental study on gas absorption into falling liquid film formed on inner surface of vertical tubes has been carried out in order to clarify fundamental characteristics of the gas absorption and enhancement by surface waves. The water supplied into the test tubes is periodically disturbed by fluctuating a silicon tube before the test section with a speaker and the wavy films absorb the oxygen filled in the tubes. Imposing the periodic disturbance enhances the gas absorption and the enhancement has a maximum at around 20-30 Hz, where the gas absorption is 20-30% higher. Mass transfer coefficients obtained with five tubes agree well with those obtained with single tube. Two-dimensional numerical simulations have also been conducted for gas absorption by wavy film and the enhancement mechanism of the gas absorption is discussed. 相似文献
109.
Jalal Salami Akio Shibata Daniel Meier Edgar Kochka Satoshi Yamanaka Preston Davis John Easoz Toru Abe Kazuo Kinoshita 《Solar Energy Materials & Solar Cells》1997,48(1-4)
This paper presents, for the first time, a low-cost, high-throughput manufacturing approach for fabricating n-base dendritic web silicon solar cells with selectively doped emitters and self-aligned aluminum contacts using rapid thermal processing (RTP) and screen printing. The self-aligned locally diffused emitter (SALDE) structure is p+ nn++ where aluminum is screen-printed on a boron-doped emitter and fired in a belt furnace to form a deep self-doped p+-layer and a self-aligned positive contact to the emitter according to the well-known aluminum-silicon (Al---Si) alloying process. The SALDE structure preserves the shallow emitter (20.2 μm) everywhere except directly beneath the emitter contact. There the junction depth is greater than 5 μm, as desired, in order to shield carriers in the bulk silicon from that part of the silicon surface covered by metal where the recombination rate is high. This structure is realized by using n-base (rather than p-base) substrates and by utilizing screen-printed aluminum (rather than silver) emitter contacts. Prototype dendritic web silicon (web) cells (25 cm2 area) with efficiencies up to 13.2% have been produced. 相似文献
110.
A novel sealing material based on a CNT-rubber composite was developed for use in producing oil from deep, hot reservoirs. Fully dispersed and better bondings are two critical advances that enhance its mechanical properties. Authors solved the critical issues and clarified the mechanism of nano network reinforcement using test data. The resulting sealing solution underwent field tests around the world, and it marks a rare success story for the use of nanotechnology in the oilfield. 相似文献