全文获取类型
收费全文 | 82347篇 |
免费 | 457篇 |
国内免费 | 383篇 |
专业分类
化学 | 26435篇 |
晶体学 | 838篇 |
力学 | 6796篇 |
数学 | 32631篇 |
物理学 | 16487篇 |
出版年
2021年 | 86篇 |
2020年 | 65篇 |
2018年 | 10467篇 |
2017年 | 10299篇 |
2016年 | 6173篇 |
2015年 | 947篇 |
2014年 | 416篇 |
2013年 | 562篇 |
2012年 | 3969篇 |
2011年 | 10716篇 |
2010年 | 5783篇 |
2009年 | 6177篇 |
2008年 | 6679篇 |
2007年 | 8847篇 |
2006年 | 296篇 |
2005年 | 1386篇 |
2004年 | 1605篇 |
2003年 | 2040篇 |
2002年 | 1083篇 |
2001年 | 302篇 |
2000年 | 359篇 |
1999年 | 227篇 |
1998年 | 260篇 |
1997年 | 213篇 |
1996年 | 270篇 |
1995年 | 177篇 |
1994年 | 136篇 |
1993年 | 158篇 |
1992年 | 109篇 |
1991年 | 116篇 |
1990年 | 114篇 |
1989年 | 118篇 |
1988年 | 104篇 |
1987年 | 125篇 |
1986年 | 96篇 |
1985年 | 101篇 |
1984年 | 106篇 |
1983年 | 97篇 |
1982年 | 101篇 |
1981年 | 100篇 |
1980年 | 93篇 |
1979年 | 108篇 |
1978年 | 90篇 |
1977年 | 63篇 |
1976年 | 78篇 |
1975年 | 75篇 |
1974年 | 57篇 |
1973年 | 65篇 |
1972年 | 57篇 |
1966年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
1.
Zakrajšek Srečko Rajkovič Vladislav Bernik Mojca Jereb Eva Rajkovič Uroš 《Central European Journal of Operations Research》2021,29(3):841-857
Central European Journal of Operations Research - Digital competences are among the most important competences in modern society, with the education system playing a key role in the acquisition of... 相似文献
2.
Tomáš Hložek Martin Štícha Miroslava Bursová Ivan Jelínek Petr Tůma Radomír Čabala 《Electrophoresis》2020,41(18-19):1564-1567
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR. 相似文献
3.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
4.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
5.
6.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
7.
8.
9.
10.
Lubomír Havlk Jan Fbry Margarida Henriques Michal Duek 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(7):623-630
The title structures of KScS2 (potassium scandium sulfide), RbScS2 (rubidium scandium sulfide) and KLnS2 [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2 and KTbS2) or redetermined. All of them belong to the α‐NaFeO2 structure type in agreement with the ratio of the ionic radii r3+/r+. KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared are c, a and c/a, the thicknesses of the S—S layers which contain the respective constituent cations, the sulfur fractional coordinates z(S2−) and the bond‐valence sums. 相似文献