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81.
VP26 is a 12-kDa capsid protein of herpes simplex virus 1. Although VP26 is dispensable for assembly, the native capsid (a T=16 icosahedron) contains 900 copies: six on each of the 150 hexons of VP5 (149 kDa) but none on the 12 VP5 pentons at its vertices. We have investigated this interaction by expressing VP26 in Escherichia coli and studying the properties of the purified protein in solution and its binding to capsids. Circular dichroism spectroscopy reveals that the conformation of purified VP26 consists mainly of beta-sheets (approximately 80%), with a small alpha-helical component (approximately 15%). Its state of association was determined by analytical ultracentrifugation to be a reversible monomer-dimer equilibrium, with a dissociation constant of approximately 2 x 10(-5) M. Bacterially expressed VP26 binds to capsids in the normal amount, as determined by quantitative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cryoelectron microscopy shows that the protein occupies its usual sites on hexons but does not bind to pentons, even when available in 100-fold molar excess. Quasi-equivalence requires that penton VP5 must differ in conformation from hexon VP5: our data show that in mature capsids, this difference is sufficiently pronounced to abrogate its ability to bind VP26.  相似文献   
82.
The purpose of this ongoing study is to evaluate the safety and efficacy of new minimally invasive pervaginam cystourethropexy and sling procedures for the treatment of female genuine stress urinary incontinence. A total of 75 women (mean age, 52.8 years) underwent either a cystourethropexy or a sling procedure. A miniature bone anchor and a staple-like bone anchor driver were used for the fixation of periurethral tissue or a xenogenic sling to the pubic bone. With a mean follow-up of eight months, 61 patients (82%) were completely cured of stress incontinence, 10 (14%) reported a more than 50% decrease in pad usage, and 4 patients showed failure early following surgery. The exclusively pervaginam cystourethropexy and sling procedures are minimally invasive, safe, and effective. Further experience and longer follow-up are necessary to establish their role in the treatment of women with stress urinary incontinence.  相似文献   
83.
Optimal gene therapy for many disorders will require efficient transfer to cells in vivo, high-level and long-term expression, and tissue-specific regulation, all in the absence of significant toxicity or inflammatory responses. While recombinant adenoviral vectors are efficient for gene transfer to hepatocytes, their usefulness is limited by short duration of expression related, at least in part, to immune responses to viral proteins and by a low capacity for foreign DNA. A number of systems have been developed for producing adenoviral vectors devoid of all viral coding sequences. Using AdSTK109, a vector lacking all viral coding sequences and carrying the complete human alpha1-antitrypsin (hAAT) genomic DNA locus, we have demonstrated sustained expression for longer than 10 months in mice. Utilizing high doses of this vector for hepatic gene transfer in mice, we find that supraphysiological levels of hAAT can be achieved without hepatotoxicity.  相似文献   
84.
85.
Using atomic force microscopy (AFM), we have investigated neutron-induced DNA double-strand breaks in plasmids in aqueous solution. AFM permits direct measurement of individual DNA molecules with an accuracy of a few nanometers. Furthermore, the analysis of the DNA fragment size distribution is non-parametric, whereas other methods are dependent on the model. Neutron irradiation of DNA results in the generation of many short fragments, an observation not made for damage induced by low-LET radiation. These data provide clear experimental evidence for the existence of clustered DNA double-strand breaks and demonstrate that short DNA fragments may be produced by such radiations in the absence of a nucleosomal DNA structure.  相似文献   
86.
Vehicular communication systems are on the verge of practical deployment. Nonetheless, their security and privacy protection is one of the problems that have been addressed only recently. In order to show the feasibility of secure VC, certain implementations are required. In [1] we discuss the design of a VC security system that has emerged as a result of the European SeVe- Com project. In this second article we discuss various issues related to the implementation and deployment aspects of secure VC systems. Moreover, we provide an outlook on open security research issues that will arise as VC systems develop from today?s simple prototypes to fullfledged systems.  相似文献   
87.
As system reliability becomes increasingly dependent on integrated circuit reliability it is essential to achieve high reliability at low cost. In this paper we will discuss the reliability of CMOS I.C.'s. Design and manufacturing considerations which are used to build reliability into the product will be discussed. Industry standard accelerated life testing was used to evaluate the product in epoxy packages.  相似文献   
88.
Fabrication of low-loss IR-transmitting Ge30As10Se30Te30 glass fibers   总被引:1,自引:0,他引:1  
Improved purification and processing techniques have been utilized to fabricate Ge30As10Se30Te30 glass fibers with a minimum loss of O.11 dB/m at 6.6 μm. This is the lowest loss reported for any telluride glass fiber in the infrared region. Furthermore, the fibers exhibit less than 1 dB/m loss between 5.25 and 9.5 μm  相似文献   
89.
The two-channel system previously reported has been implemented in hardware using system parameters appropriate to consumer television. The basic system divides the spectrum into lowand high-frequency spatial components. The lows are coarsely sampled and finely quantized and the highs finely sampled and coarsely quantized using a companded, randomized quantizer. The purpose of this experiment was to demonstrate the potential of the system for low-cost practical application, to study the effect of the character of the randomizing noise, and to ascertain that there were no deleterious effects due to interlace, motion, or input noise. Theoretical noise calculations were qualitatively confirmed.  相似文献   
90.
Minimum-energy multicast in mobile ad hoc networks using network coding   总被引:6,自引:0,他引:6  
The minimum energy required to transmit one bit of information through a network characterizes the most economical way to communicate in a network. In this paper, we show that, under a layered model of wireless networks, the minimum energy-per-bit for multicasting in a mobile ad hoc network can be found by a linear program; the minimum energy-per-bit can be attained by performing network coding. Compared with conventional routing solutions, network coding not only allows a potentially lower energy-per-bit to be achieved, but also enables the optimal solution to be found in polynomial time, in sharp contrast with the NP-hardness of constructing the minimum-energy multicast tree as the optimal routing solution. We further show that the minimum energy multicast formulation is equivalent to a cost minimization with linear edge-based pricing, where the edge prices are the energy-per-bits of the corresponding physical broadcast links. This paper also investigates minimum energy multicasting with routing. Due to the linearity of the pricing scheme, the minimum energy-per-bit for routing is achievable by using a single distribution tree. A characterization of the admissible rate region for routing with a single tree is presented. The minimum energy-per-bit for multicasting with routing is found by an integer linear program. We show that the relaxation of this integer linear program, studied earlier in the Steiner tree literature, can now be interpreted as the optimization for minimum energy multicasting with network coding. In short, this paper presents a unifying study of minimum energy multicasting with network coding and routing.  相似文献   
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