全文获取类型
收费全文 | 1732篇 |
免费 | 29篇 |
国内免费 | 6篇 |
专业分类
化学 | 1214篇 |
晶体学 | 23篇 |
力学 | 17篇 |
数学 | 119篇 |
物理学 | 394篇 |
出版年
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 29篇 |
2015年 | 19篇 |
2014年 | 14篇 |
2013年 | 65篇 |
2012年 | 70篇 |
2011年 | 71篇 |
2010年 | 51篇 |
2009年 | 50篇 |
2008年 | 102篇 |
2007年 | 94篇 |
2006年 | 96篇 |
2005年 | 122篇 |
2004年 | 94篇 |
2003年 | 89篇 |
2002年 | 80篇 |
2001年 | 41篇 |
2000年 | 45篇 |
1999年 | 29篇 |
1998年 | 15篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 15篇 |
1992年 | 21篇 |
1991年 | 16篇 |
1990年 | 27篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 21篇 |
1985年 | 21篇 |
1984年 | 41篇 |
1983年 | 14篇 |
1982年 | 32篇 |
1981年 | 26篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 12篇 |
1977年 | 17篇 |
1976年 | 14篇 |
1975年 | 16篇 |
1974年 | 10篇 |
1968年 | 12篇 |
1967年 | 12篇 |
排序方式: 共有1767条查询结果,搜索用时 15 毫秒
201.
Nobuo Inagaki Pranab Kumar Sen 《Annals of the Institute of Statistical Mathematics》1985,37(1):251-269
Summary The basic regularity conditions pertaining to the asymptotic theory of progressively truncated likelihood functions and maximum
likelihood estimators are considered, and the uniform strong consistency and weak convergence of progressively truncated maximum
likelihood estimators are studied systematically.
Work done during the first author's visit (as a visiting scholar) to the University of North Carolina at Chapel Hill, supported
by the Ministry of Education of the Japanese Government.
Work supported by the (U.S.) National Heart, Lung and Blood Institute, Contact NIH-NHLBI-F1-2243-L. 相似文献
202.
The vibrational spectrum of thionyl fluoride, SOF2, has been reinvestigated by means of high resolution infrared and Raman spectroscopy. Substitution of oxygen-16 by oxygen-18 led to a definitive identification of those modes to which sulfur-oxygen motion makes a large contribution. The band structure of the sulfur-oxygen stretching vibration, which is obscured by Fermi resonance with a combination band in S16OF2, has been resolved in S18OF2. The experimental isotopic splittings are compared with those calculated by previous investigators. 相似文献
203.
Fumiaki Watanabe Mitsuko Masutani Nobuo Kamada Hiroshi Suzuki Hitoshi Nakagama Takashi Sugimura Hirobumi Teraoka 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(6):248
One immediate cellular response to DNA damage is the polyADP-ribosylation reaction by poly(ADP-ribose) polymerase-1 (Parp-1). The importance of Parp-1 has been established in many cellular processes, such as the maintenance of genomic stability, DNA repair and cell-death induction. Here, we established Parp-1−/− mice of C57BL/6J congenic strain and characterized the role of Parp-1 in cell-cycle progression. In this study, we also improved a method to observe G0/G1 to S-phase transition of splenocytes and bone marrow cells prepared from mice. The cells were cultured and stimulated with mitogens (50 μM ionomycin/1 μM phorbol 12, 13-dibutyrate). We found that addition of a commercially available growth supportive reagent, BM Condimed RH1, greatly enhanced the transition of G0/G1 to the S-phase, which was determined by bromodeoxyuridine (BrdU) incorporation to DNA. Using this method, G0/G1 to the S-phase entry was measured using splenocytes derived from Parp-1−/−, Parp-1+/− and wild-type (Parp-1+/+) mice. DNA synthesis in Parp-1+/+ and Parp-1+/− splenocytes started from day 1 after addition of mitogens, whereas that in Parp-1−/− cells started from day 2. The peak of the S-phase was at day 2 in all genotypes and notably DNA synthesis in Parp-1−/− cells was approximately halved compared to Parp-1+/+ cells on day 2, 3 and 4. These results suggested that Parp-1 is involved in positive regulation of S-phase entry in quiescent mouse splenocytes. 相似文献
204.
205.
The simultaneous determination of alkaline-earth metal ions in acid solution was studied by modified normal pulse polarography. Well-defined waves were recorded for calcium, strontium and barium, but no limiting current was found for magnesium, because of its very negative reduction potential. The differential mode of this method gives peak-type polarograms and is useful for the simultaneous determination of species for which the half-wave potentials lie close together. The interference of dissolved oxygen was eliminated by the use of tetramethylammonium chloride as a supporting electrolyte. 相似文献
206.
Hexafluoroacetone reacted with diphenylketene in the presence of potassium fluoride to give a 1:1 cycloadduct of β-lactone structure. On the other hand, hexafluorothioacetone, liberated from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane by potassium fluoride, reacted with diphenylketene to give a “reverse” cycloadduct, a 3-thietanone derivative. Several reactions ofthe above product, including a reductive desulfuration of the 3-thietanone derivative were carried out. 相似文献
207.
208.
Takahiko Hara 《Annals of the Institute of Statistical Mathematics》1988,40(2):395-406
This paper is concerned with two kinds of multiple outlier problems in multivariate regression. One is a multiple location-slippage problem and the other is a multiple scale-inflation problem. A multi-decision rule is proposed. Its optimality is shown for the first problem in a class of left orthogonally invariant distributions and is also shown for the second problem in a class of elliptically contoured distributions. Thus the decision rule is robust against departures from normality. Further the null robustness of the decision statistic which the rule is based on is pointed out in each problem. 相似文献
209.
A laser Doppler imaging system with a TV camera has been constructed and velocity distributions of fluid flow in cross sections of a rectangular channel have been measured. Consequently, it has been found that the system has some advantages in comparison with usual laser Doppler velocimeters, for example, the visualization of flow can be easily achieved. 相似文献
210.
Xestospongin A,B,C and D represent a new class of macrocyclic 1-oxaquinolizidines, have been isolated from Australian sponge . The structure of xestospongin C has been determined by X-ray analysis. 相似文献