全文获取类型
收费全文 | 9861篇 |
免费 | 1388篇 |
国内免费 | 1124篇 |
专业分类
化学 | 7255篇 |
晶体学 | 107篇 |
力学 | 517篇 |
综合类 | 146篇 |
数学 | 1316篇 |
物理学 | 3032篇 |
出版年
2023年 | 169篇 |
2022年 | 197篇 |
2021年 | 294篇 |
2020年 | 372篇 |
2019年 | 357篇 |
2018年 | 285篇 |
2017年 | 302篇 |
2016年 | 476篇 |
2015年 | 428篇 |
2014年 | 586篇 |
2013年 | 760篇 |
2012年 | 904篇 |
2011年 | 912篇 |
2010年 | 659篇 |
2009年 | 579篇 |
2008年 | 649篇 |
2007年 | 558篇 |
2006年 | 477篇 |
2005年 | 391篇 |
2004年 | 374篇 |
2003年 | 327篇 |
2002年 | 363篇 |
2001年 | 276篇 |
2000年 | 187篇 |
1999年 | 229篇 |
1998年 | 148篇 |
1997年 | 119篇 |
1996年 | 130篇 |
1995年 | 111篇 |
1994年 | 104篇 |
1993年 | 95篇 |
1992年 | 85篇 |
1991年 | 79篇 |
1990年 | 53篇 |
1989年 | 55篇 |
1988年 | 34篇 |
1987年 | 31篇 |
1986年 | 34篇 |
1985年 | 33篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1977年 | 5篇 |
1963年 | 7篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 15篇 |
1956年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Gang Li Feng Feng Huang T.C.E. Cheng Quan Zheng Ping Ji 《European Journal of Operational Research》2014
We consider a supply chain comprising a manufacturer and a retailer. The manufacturer supplies a product to the retailer, while the retailer sells the product bundled with after-sales service to consumers in a fully competitive market. The sales volume is affected by the retailer’s service-level commitment. The retailer can build service capacity in-house at a deterministic price before service demand is realized, or buy the service from an outsourcing market at an uncertain price after service demand realization. We find that the outsourcing market encourages the retailer to make a higher level of service commitment, while prompting the manufacturer to reduce the wholesale price, resulting in more demand realization. We analyze how the expected cost of the service in the outsourcing market and the retailer’s risk attitude affect the decisions of both parties. We derive the conditions under which the retailer is willing to build service capacity in-house and under which it will buy the service from the outsourcing market. Moreover, we find that the manufacturer’s sharing with the retailer the cost to build service capacity improves the profits of both parties. 相似文献
992.
993.
The polytropic filtration equation with generalized Fisher–KPP sources is considered. We will show that the equation may have finite times oscillatory traveling waves, and try to give a complete classification by virtue of a singular exponent in the source according to the finiteness of the oscillatory times of traveling waves. 相似文献
994.
Let $F$ be a proper rational map from the complex ball $\mathbb B ^n$ into $\mathbb B ^N$ with $n>7$ and $3n+1 \le N\le 4n-7$ . Then $F$ is equivalent to a map $(G, 0, \dots , 0)$ where $G$ is a proper holomorphic map from $\mathbb B ^n$ into $\mathbb B ^{3n}$ . 相似文献
995.
Byeong Moon Kim Ji Young Kim Poo-Sung Park 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2014,84(1):17-29
A Hermitian lattice over an imaginary quadratic field $\mathbb {Q}(\sqrt{-m})$ is called almost universal if it represents all but finitely many positive integers. We investigate almost universal binary Hermitian lattices and provide a Bochnak-Oh type criterion on almost universality. In particular, all almost universal $p$ -anisotropic binary Hermitian lattices are universal, and we give the complete list of all such Hermitian lattices. 相似文献
996.
Generally, supply chain cluster (SCC) evolution follows innovation and its selection strategies. To further reduce the innovation risk, SCC must seek the feasible innovation strategies to match ecological niche-matching degree; within a competing cluster, it should avoid the hazardous nature of pure competition that affects the innovation output, and within a cooperation innovation cluster it should look carefully for the cooperation innovation mechanism. This paper examines the impact of growth of SCC from a perspective of ecological niche, the innovation strategy and the expansion of ecological niche, and its matching degree on the influence of the growth in SCC; and presents the ecological niche expansion model, growth model and growth evolution model of SCC. The findings of this research suggest that there is a five-stage evolution of which the characteristic is different in different innovation strategies. The ecological niche width of SCC is connected by each member’s ecological niche, and the expansion process is constituted by the members’ ecological niche expansion. In each stage, SCC should identify ecological niche-matching degree between members and innovation modes when the SCC expands the niche width to a certain limit. Finally, a case study demonstrates the application potential of the model and its implications. 相似文献
997.
We consider properties related to weighted composition operators boundedly acting from the classical Hardy space H p to H q for \({1 \leq q < p < \infty}\) . Especially, we shall completely determine path connected components in the set of weighted composition operators and explicitly characterize by function-theoretic properties of analytic self-maps. 相似文献
998.
We introduce the Besov space $\dot{B}^{0,L}_{1,1}$ associated with the Schrödinger operator L with a nonnegative potential satisfying a reverse Hölder inequality on the Heisenberg group, and obtain the molecular decomposition. We also develop the Hardy space $H_{L}^{1}$ associated with the Schrödinger operator via the Littlewood–Paley area function and give equivalent characterizations via atoms, molecules, and the maximal function. Moreover, using the molecular decomposition, we prove that $\dot{B}^{0,L}_{1,1}$ is a subspace of $H_{L}^{1}$ . 相似文献
999.
Leader‐following consensus problem of heterogeneous multi‐agent systems with nonlinear dynamics using fuzzy disturbance observer 下载免费PDF全文
This article considers the leader‐following consensus problem of heterogeneous multi‐agent systems. The proposed multi‐agent system is consisted of heterogeneous agents where each agents have their own nonlinear dynamic behavior. To overcome difficulty from heterogeneous nonlinear intrinsic dynamics of agents, a fuzzy disturbance observer is adopted. In addition, based on the Lyapunov stability theory, an adaptive control method is used to compensate the observation error caused by the difference between the unknown factor and estimated values. Two numerical examples are given to illustrate the effectiveness of the proposed method. © 2013 Wiley Periodicals, Inc. Complexity 19: 20–31, 2014 相似文献
1000.
Tail asymptotics of supremum of certain Gaussian processes over threshold dependent random intervals
Let {X(t),t ≥ 0} be a centered Gaussian process and let γ be a non-negative constant. In this paper we study the asymptotics of \(\mathbb {P} \left \{\underset {t\in [0,\mathcal {T}/u^{\gamma }]}\sup X(t)>u\right \}\) as \(u\rightarrow \infty \) , with \(\mathcal {T}\) an independent of X non-negative random variable. As an application, we derive the asymptotics of finite-time ruin probability of time-changed fractional Brownian motion risk processes. 相似文献