全文获取类型
收费全文 | 7977篇 |
免费 | 825篇 |
国内免费 | 978篇 |
专业分类
化学 | 1667篇 |
晶体学 | 28篇 |
力学 | 523篇 |
综合类 | 249篇 |
数学 | 6097篇 |
物理学 | 1216篇 |
出版年
2024年 | 9篇 |
2023年 | 62篇 |
2022年 | 115篇 |
2021年 | 146篇 |
2020年 | 206篇 |
2019年 | 214篇 |
2018年 | 224篇 |
2017年 | 238篇 |
2016年 | 319篇 |
2015年 | 214篇 |
2014年 | 375篇 |
2013年 | 590篇 |
2012年 | 402篇 |
2011年 | 504篇 |
2010年 | 442篇 |
2009年 | 572篇 |
2008年 | 584篇 |
2007年 | 559篇 |
2006年 | 530篇 |
2005年 | 412篇 |
2004年 | 373篇 |
2003年 | 401篇 |
2002年 | 341篇 |
2001年 | 255篇 |
2000年 | 253篇 |
1999年 | 218篇 |
1998年 | 198篇 |
1997年 | 198篇 |
1996年 | 157篇 |
1995年 | 100篇 |
1994年 | 92篇 |
1993年 | 79篇 |
1992年 | 65篇 |
1991年 | 51篇 |
1990年 | 29篇 |
1989年 | 24篇 |
1988年 | 33篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 25篇 |
1983年 | 15篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1936年 | 5篇 |
排序方式: 共有9780条查询结果,搜索用时 31 毫秒
1.
Xin Liu Lili Chen Yanfeng Zhao Xianhua Song 《Mathematical Methods in the Applied Sciences》2022,45(1):77-92
In this paper, the problem of the uniform stability for a class of fuzzy fractional-order genetic regulatory networks with random discrete delays, distributed delays, and parameter uncertainties is studied. Although there is a portion of literature on using fixed point theorems to study the stability of fractional neural networks, most of them required the fractional order to be in . However, the case of the fractional-order belonging to has not been discussed. To solve it, this work proposes a novel idea of using fixed point theory to study the stability of fuzzy (0,1) order neural networks, the problem of the uniqueness of the solution of the considered genetic regulatory networks is resolved, and a novel sufficient condition to guarantee the uniform stability of above genetic regulatory networks is also derived. Eventually, an example is given to demonstrate that the obtained result is effective. 相似文献
2.
In this paper, the authors discuss a generalization of Lappan’s theorem to higher dimensional complex projective space and get the following result: Let f be a holomorphic mapping of ? into Pn(C), and let H1, · · · , Hq be hyperplanes in general position in Pn(C).Assume that sup {(1 ? |z|2)f?(z) : z ∈ q[ j=1 f?1(Hj )o < ∞,if q ≥ 2n2 + 3, then f is normal. 相似文献
3.
A reflective subuniverse in homotopy type theory is an internal version of the notion of a localization in topology or in the theory of ∞-categories. Working in homotopy type theory, we give new characterizations of the following conditions on a reflective subuniverse L: (1) the associated subuniverse of L-separated types is a modality; (2) L is a modality; (3) L is a lex modality; and (4) L is a cotopological modality. In each case, we give several necessary and sufficient conditions. Our characterizations involve various families of maps associated to L, such as the L-étale maps, the L-equivalences, the L-local maps, the L-connected maps, the unit maps , and their left and/or right orthogonal complements. More generally, our main theorem gives an overview of how all of these classes related to each other. We also give examples that show that all of the inclusions we describe between these classes of maps can be strict. 相似文献
4.
5.
6.
以轻烧白云石粉、氯化铵和二氧化碳为原料,在未使用晶型控制剂的情况下,通过蒸氨-沉钙过程制备出了似立方体状碳酸钙。研究了反应温度、溶液中钙离子浓度、通气速率、搅拌速度以及陈化时间对碳酸钙中方解石相含量以及晶体形貌的影响,并探索了沉钙反应的晶型控制机理。结果表明,在反应温度40 ℃、钙离子浓度0.05 mol/L、通碳速率100 mL/min、搅拌速度400 r/min和陈化时间2 h的条件下,制备出形貌规整、粒径分布均匀的似立方体状碳酸钙,平均粒径为5~10 μm。该研究为提升白云石的使用价值、生产高附加价值的碳酸钙产品,以及提高白云石资源的利用率提供理论基础。 相似文献
7.
8.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates. 相似文献
9.
10.
Awatif Alqahtani Mohamed Jleli Bessem Samet 《Mathematical Methods in the Applied Sciences》2019,42(3):861-870
In this paper, some nonlocal in time differential inequalities of Sobolev type are considered. Using the nonlinear capacity method, sufficient conditions for the nonexistence of nontrivial global classical solutions are provided. 相似文献