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81.
J Ellert-Zygad?owska D Radowska M Dubicka H Trocha M Or?owski J Magiera 《Canadian Metallurgical Quarterly》1996,41(1):62-68
We biologically assessed functions of several reconstituted surfactants with the same minimum surface tension (2-3 mN/m) as "complete" porcine pulmonary surfactant (natural surfactant) but with longer surface adsorption times. Administration of natural surfactant (adsorption time 0.29 s) into the lungs of surfactant-deficient immature rabbits brought a tidal volume of 16.1 +/- 4.4 (SD) ml/kg during mechanical ventilation with 40 breaths/min and 20 cmH2O insufflation pressure. In static pressure-volume recordings, these animals showed a lung volume of 62.4 +/- 9.7 ml/kg at 30 cmH2O airway pressure and maintained 55% of this volume when the pressure decreased to 5 cmH2O. With two reconstituted surfactants consisting of synthetic lipids or isolated lipids from porcine lungs plus surfactant-associated hydrophobic proteins (adsorption times 0.57 and 0.78 s, respectively), tidal volumes were < 38% of that with natural surfactant (P < 0.05), but static pressure-volume recordings were not different. Care is therefore needed in estimating the in vivo function of surfactant preparations from minimum surface tension or static pressure-volume measurements. 相似文献
82.
Adam Kłodowski Timo Rantalainen Aki Mikkola Ari Heinonen Harri Sievänen 《Multibody System Dynamics》2011,25(4):395-409
A method for bone strain estimation is examined in this article. The flexibility of a single bone in an otherwise rigid human
skeleton model has been studied previously by various authors. However, in the previous studies, the effect of the flexibility
of multiple bones on the musculoskeletal model behavior was ignored. This study describes a simulation method that can be
used to estimate the bone strains at both tibias and femurs of a 65-year-old Caucasian male subject. The verification of the
method is performed by the comparison of the results with other studies available in literature. The results of the study
show good correlation with the results of previous empirical studies. A damping effect of the flexible bones on the model
is also studied in this paper. 相似文献
83.
84.
The paper addresses the problem of multi-slot just-in-time scheduling. Unlike the existing literature on this subject, it
studies a more general criterion—the minimization of the schedule makespan rather than the minimization of the number of slots
used by schedule. It gives an O(nlog 2
n)-time optimization algorithm for the single machine problem. For arbitrary number of m>1 identical parallel machines it presents an O(nlog n)-time optimization algorithm for the case when the processing time of each job does not exceed its due date. For the general
case on m>1 machines, it proposes a polynomial time constant factor approximation algorithm. 相似文献
85.
86.
We consider deterministic distributed broadcasting on multiple access channels in the framework of adversarial queuing. Packets
are injected dynamically by an adversary that is constrained by the injection rate and the number of packets that may be injected
simultaneously; the latter we call burstiness. A protocol is stable when the number of packets in queues at the stations stays
bounded. The maximum injection rate that a protocol can handle in a stable manner is called the throughput of the protocol.
We consider adversaries of injection rate 1, that is, of one packet per round, to address the question if the maximum throughput
1 can be achieved, and if so then with what quality of service. We develop a protocol that achieves throughput 1 for any number
of stations against leaky-bucket adversaries. The protocol has
O(n2+\textburstiness){\mathcal{O}(n^2+\text{burstiness})} packets queued simultaneously at any time, where n is the number of stations; this upper bound is proved to be best possible. A protocol is called fair when each packet is
eventually broadcast. We show that no protocol can be both stable and fair for a system of at least two stations against leaky-bucket adversaries. We study in detail small systems of exactly
two and three stations against window adversaries to exhibit differences in quality of broadcast among classes of protocols.
A protocol is said to have fair latency if the waiting time of packets is
O(\textburstiness){\mathcal{O}(\text{burstiness})}. For two stations, we show that fair latency can be achieved by a full sensing protocol, while there is no stable acknowledgment
based protocol. For three stations, we show that fair latency can be achieved by a general protocol, while no full sensing
protocol can be stable. Finally, we show that protocols that either are fair or do not have the queue sizes affect the order
of transmissions cannot be stable in systems of at least four stations against window adversaries. 相似文献
87.
Marcin Miłkowski 《Minds and Machines》2009,19(4):465-475
In Darwin’s Dangerous Idea, Daniel Dennett claims that evolution is algorithmic. On Dennett’s analysis, evolutionary processes are trivially algorithmic
because he assumes that all natural processes are algorithmic. I will argue that there are more robust ways to understand
algorithmic processes that make the claim that evolution is algorithmic empirical and not conceptual. While laws of nature
can be seen as compression algorithms of information about the world, it does not follow logically that they are implemented
as algorithms by physical processes. For that to be true, the processes have to be part of computational systems. The basic
difference between mere simulation and real computing is having proper causal structure. I will show what kind of requirements
this poses for natural evolutionary processes if they are to be computational. 相似文献
88.
Tomasz Fałat Kazimierz Friedel Norman Marenco Stephan Warnat 《Microsystem Technologies》2009,15(1):181-190
The current paper focuses on several mechanical aspects of a waferlevel packaging approach using a direct face-to-face Chip-to-Wafer
(C2W) bonding of a MEMS device on an ASIC substrate wafer. Requirements of minimized inherent stress from packaging and good
decoupling from forces applied in manufacturing and application are discussed with particular attention to the presence of
through-silicon vias (TSV) in the substrate wafer. The paper deals with FEM analysis of temperature excursion, pressure during
molding, materials used and handling load influence on mechanical stress within the TSV system and on wafer level, which can
be large enough to disintegrate the system. 相似文献
89.
90.
Marcin Bienkowski Marek Klonowski Miroslaw Korzeniowski Dariusz R. Kowalski 《Distributed Computing》2016,29(5):341-359
In this paper we consider the mutual exclusion problem on a multiple access channel. Mutual exclusion is one of the fundamental problems in distributed computing. In the classic version of this problem, n processes execute a concurrent program that occasionally triggers some of them to use shared resources, such as memory, communication channel, device, etc. The goal is to design a distributed algorithm to control entries and exits to/from the shared resource (also called a critical section), in such a way that at any time, there is at most one process accessing it. In our considerations, the shared resource is the shared communication channel itself (multiple access channel), and the main challenge arises because the channel is also the only mean of communication between these processes. We consider both the classic and a slightly weaker version of mutual exclusion, called \(\varepsilon \)-mutual-exclusion, where for each period of a process staying in the critical section the probability that there is some other process in the critical section is at most \(\varepsilon \). We show that there are channel settings, where the classic mutual exclusion is not feasible even for randomized algorithms, while the \(\varepsilon \)-mutual-exclusion is. In more relaxed channel settings, we prove an exponential gap between the makespan complexity of the classic mutual exclusion problem and its weaker \(\varepsilon \)-exclusion version. We also show how to guarantee fairness of mutual exclusion algorithms, i.e., that each process that wants to enter the critical section will eventually succeed. 相似文献