全文获取类型
收费全文 | 1284篇 |
免费 | 41篇 |
国内免费 | 13篇 |
专业分类
化学 | 988篇 |
晶体学 | 29篇 |
力学 | 9篇 |
数学 | 68篇 |
物理学 | 244篇 |
出版年
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 33篇 |
2015年 | 34篇 |
2014年 | 25篇 |
2013年 | 53篇 |
2012年 | 56篇 |
2011年 | 88篇 |
2010年 | 41篇 |
2009年 | 38篇 |
2008年 | 67篇 |
2007年 | 67篇 |
2006年 | 70篇 |
2005年 | 55篇 |
2004年 | 68篇 |
2003年 | 51篇 |
2002年 | 47篇 |
2001年 | 48篇 |
2000年 | 30篇 |
1999年 | 30篇 |
1998年 | 19篇 |
1997年 | 13篇 |
1996年 | 20篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 21篇 |
1986年 | 12篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 15篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1972年 | 6篇 |
1967年 | 5篇 |
排序方式: 共有1338条查询结果,搜索用时 15 毫秒
1.
We study the relation between the cohomology of general linear and symmetric groups and their respective quantizations, using Schur algebras and standard homological techniques to build appropriate spectral sequences. As our methods fit inside a much more general context within the theory of finite-dimensional algebras, we develop our results first in that general setting, and then specialize to the above situations. From this we obtain new proofs of several known results in modular representation theory of symmetric groups. Moreover, we reduce certain questions about computing extensions for symmetric groups and Hecke algebras to questions about extensions for general linear groups and their quantizations. 相似文献
2.
Aging of concrete buildings and determining the pH value on the surface of concrete by using a handy semi-conductive pH meter. 总被引:1,自引:0,他引:1
A new method was devised for measuring the pH of a concrete surface by pHBOY-P2 with a piece of filter paper by extracting the pH value from concrete. This is a simple and inexpensive method that does not damage the concrete building, and is easy to apply on concrete samples for monitoring. By using the method mentioned above, a drastic decrease of the pH value of concrete bridges and buildings has investigated. The method is environmentally friendly to detect the pH value change of concrete as an environmental sample investigation. 相似文献
3.
4.
S. Nakano Y. Kuwano M. Ohnishi 《Applied Physics A: Materials Science & Processing》1986,41(4):267-274
The super chamber, a separated UHV reaction-chamber system has been developed. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method.As a new material, amorphous superlattice-structure films were fabricated by the photo-CVD method for the first time. Superlattice structure p-layer a-Si solar cells were fabricated, and a conversion efficiency of 10.5% was obtained.For the fabrication of integrated type a-Si solar cell modules, a laser pattering method was investigated. A thermal analysis of the multilayer structure was done. It was confirmed that selective scribing for a-Si, TCO and metal film is possible by controlling the laser power density. Recently developed a-Si solar power generation systems and a-Si solar cell roofing tiles are also described. 相似文献
5.
This paper presents a simple chaotic circuit consisting of two capacitors, one linear two-port VCCS and one time-state-controlled
impulsive switch. The impulsive switch causes rich chaotic and periodic behavior. The circuit dynamics can be simplified into
a one-dimensional return map that is piecewise linear and piecewise monotone. Using the return map, we clarify parameter conditions
for existence of chaotic and periodic attractors and coexistence state of attractors. 相似文献
6.
M. Fukushima H. Tamate N. Fujii Y. Nakano 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(1):105-108
In this work, we determined the levels of trace metals in protein fractions isolated from rock oysters by neutron activation analysis (NAA) and particle induced X-ray emission (PIXE). Proteins were extracted from mantles and hepatopancreases of rock oysters and fractionated by size-exclusion high performance liquid chromatography (HPLC). The protein fractions from mantles and hepatopancreases are found to be abundant in Fe, Cu, Zn, Mn, Pb, and Ag. HPLC profiles of Fe, Cu, Zn, and Ag indicate that those elements are bound to proteins extracted from mantles and hepatopancreases. 相似文献
7.
Kazuhiko Nakano Toshihiro Nakamura Izumi Nakai Akira Kawase Makoto Imai Mikio Hasegawa Yohichi Ishibashi Isamu Inamoto Kazuhuyu Sudou Masaru Kozaki Akira Tsuruta Akihiro Ono Kazutoshi Kakita Mamoru Sakata 《Analytical sciences》2006,22(9):1265-1268
The Japan Society for Analytical Chemistry has developed some new plastic certified reference materials (CRMs) for the analysis of mercury in polyester disks using XRF analysis. These CRMs (named as JSAC 0621-0625) were prepared by casting polyesters including a toluene solution of organometallic compounds as a standard. Concentrations of the five levels of mercury ranged from 0 to 250 mg/kg. Homogeneity tests of prepared disks had shown excellent results. Interlaboratory comparison study for the certification was performed by 15 laboratory participants. The z-scores in robust statistical method was applied for the evaluation of outliers. The certified values were assigned after discarding outliers. The uncertainties of certified values were determined as the confidence levels of 95%. 相似文献
8.
9.
10.
I Kanamori S Nakano M Hurukawa Y Okumura C Higuchi M Yanase M Onogi 《Radioisotopes》1988,37(8):460-463
From the clinical use of RIA-gnost trypsin kit, the following results were obtained. 1. Standard curve showed a steep and good curve was shown. 2. Incubation: The condition for the first incubation was set at the room temperature for 10-24 hours and that for the second incubation at the room temperature for 3-5 hours. With these settings, satisfactory results were obtained. 3. Reproducibility and recovery: The C.V. of the reproducibility and the recovery were considered superior, and the values were below 10% and +/- 3%, respectively. 4. Correlation between trypsin and serum elestase-1: An excellent positive correlation (coefficient of correlation r = 0.889) was shown. 5. Serum trypsin concentration of normal and pancreatic diseases: The normal range was from 100 to 500 ng/ml. Acute pancreatitis rose obviously. Diabetes mellitus and chronic pancreatitis was below 500 ng/ml and the pancreatic cancer showed a tendency to scatter in the range of 50-1,250 ng/ml. The above results indicated that serum trypsin can be easily measured with high precision by using this method. Thus the method is considered useful for the diagnosis of pancreatic diseases. 相似文献