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排序方式: 共有314条查询结果,搜索用时 15 毫秒
61.
62.
The linear killer plasmids, pGKL1 and pGKL2, from Kluyveromyces lactis stably replicated in mitochondrial DNA-deficient (rho 0) MATa or MAT alpha haploids of Saccharomyces cerevisiae, but were unstable and frequently lost in rho 0 MATa/MAT alpha diploids, suggesting that the replication of pGKL plasmids was under the control of the MAT locus. In MATa/MAT alpha cells of S. cerevisiae, the MAT alpha gene product (alpha 2) is combined with the MATa gene product (a1) and the resultant protein, a1-alpha 2, acts to repress the expression of haploid specific genes. Experiments showed that the K. lactis linear plasmids were stably maintained in rho 0 mata1/MAT alpha diploids, indicating that the a1-alpha 2 repressor interfered with the stability of pGKL2. It was revealed by computer analysis that the consensus sequence homologous to the a1-alpha 2 repressor binding site occurred within the coding regions of pGKL2 genes which were presumed to be essential for the plasmid replication. Since the plasmids were stably maintained in diploids of K. lactis, the mating type control must not be working there. 相似文献
63.
Tanzo Nitta Yasuyuki Shirai Toshikazu Kawauchi Takao Okada Yoshihiro Ogawa 《Electrical Engineering in Japan》1995,115(6):62-70
Experimental studies using20-kVA superconducting generators (SCG) have been performed in an attempt to understand some of the characteristics of SCG in power systems. It is necessary to investigate the characteristics for the parallel operations of both an SCG and a conventional generator (CG) when an SCG is installed in a present power station. Some of the results of the authors' studies on parallel running of the 20-kVA SCG and the 20-kVA CG are described in this paper. In the experimental system, the SCG is connected to a regional power system (infinite bus) through reactors (artificial transmission lines) and the CG is connected to the terminal of the SCG. Using experiments and computer simulations, the transient characteristics at three-phase short-circuit faults are investigated: 1) when the CG is not disconnected; and 2) when the CG is disconnected after reclosing the line with the fault cleared. Two kinds of stable limit curves are obtained for output power at three-phase short-circuit fault for the aforementioned two cases. 相似文献
64.
Leak flow rate and jet impingement load are experimentally evaluated using very narrow and short artificial slits which simulate a through-wall fatigue crack. The following items are clarified in the experiments under BWR fluid conditions: (1) the leak flow rate from the rectangular slit is experimentally clarified and it agrees well with the analytical result when the estimated thermodynamic nonequilibrium parameter N in the present experiment is introduced; (2) the orifice effects are experimentally evaluated concerning the through-wall fatigue crack, in which the discharge coefficients CD between 0.75 and 0.25 are obtained as a function of the exit to the stagnation area ratio Ae/Ao; (3) when very narrow and short slits are used in the jet impingement experiments, the maximum pressure on the target is higher than that of a large diameter pipe and it increases with the decrease of the flow path length to hydraulic diameter ratio L/D of the slit because of the thermodynamic nonequilibrium effect. 相似文献
65.
Elastic properties of real elastomers were examined by using partial derivatives of the strain energy density function (W) with respect to the invariant (Ii, i=1,2,3) of deformation tensor. The values of the derivatives at zero strain limit for styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR) and butadiene rubber (BR) were compared with those derived from the theory shown in the previous paper, where compressibility of the materials was taken into account. The asymptotic behavior of the derivatives for isoprene rubber (IR) and segmented polyurethaneurea (SPU) was also compared with those of the three types of rubbers. It was shown that the theoretical predictions for the limiting value agreed fairly well with the experimental values of the elastomers. 相似文献
66.
67.
The permeabilities of He, H2, N2, O2, CO2, CH4, C2H6, C3H8, and n-C4H10 in poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA) and poly[diphenylacetylene] (PDPA) are presented and compared to those of poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and polysulfone. Like PTMSP, PTMSDPA, a disubstituted glassy acetylene-based polymer, exhibits higher permeabilities to organic vapors than to permanent gases due to its rigid polyacetylene backbone and bulky side groups, which provide a relatively high fractional free volume (FFV) value of 0.26. Desilylation was performed on PTMSDPA. The resulting material, PDPA, is totally insoluble in common organic solvents, so it has much higher chemical resistance than PTMSDPA. Additionally, due to its insolubility in polymerization solvents, desilylation provides the only known route to high molar mass PDPA. The FFV of the resulting membrane (PDPA) is reduced by approximately 12% relative to that of PTMSDPA. This leads to a decrease in gas permeability values and selectivity of organic vapors relative to nitrogen. For example, the oxygen permeability is reduced from 1200 to 500 Barrers upon desilylation. The pure gas selectivities decrease from 9 to 3 for n-C4H10/N2 and from 26 to 9 for C3H8/N2. 相似文献
68.
Masaki Himejima Kenneth R. Hobson Toshikazu Otsuka David L. Wood Isao Kubo 《Journal of chemical ecology》1992,18(10):1809-1818
The oleoresin of the ponderosa pine,Pinus ponderosa (Pinaceae) exhibited broad antimicrobial activity. In order to identify the active compounds, the oleoresin was steam distilled
to give a distillate and residue. The distillate contained mainly monoterpenes and some sesquiterpenes, while the residue
consisted chiefly of four structurally related diterpene acids. An antimicrobial assay with the pure compounds indicated that
the monoterpenes were active primarily against fungi, but there was also some activity against gram-positive bacteria. The
diterpene acids, in contrast, only exhibited activity against gram-positive bacteria. Although not all of the identified sesquiterpenes
could be tested, longifolene showed activity only against gram-positive bacteria. Therefore, it appears that the oleoresin
ofP. ponderosa functions as a biochemical defense against microbial invasion. 相似文献
69.
Yoshiaki Kobayashi Toshikazu Nakamura Toshihiro Takahashi Kazushi Kanoda B. Hilti J. S. Zambounis 《Journal of Superconductivity and Novel Magnetism》1994,7(3):663-666
We report the results of our attempt to measure the proton nuclear relaxation rate, 1/T 1, in the superconducting state of the title material. The relaxation rate in the superconducting state at a field of 1 T was found much longer than that in the normal state, but it became clear that the dominant contribution came from the normal core region. The nuclear relaxation at zero field was examined by using the field cycling technique. An ln(t) term in the relaxation curve was observed at low temperatures, suggesting the contribution of the creeping motion of vortices. We discuss the possibility to determine the intrinsic temperature dependence of 1/T 1 in the superconducting state. 相似文献
70.
Toshikazu Yano Noriyuki Miyazaki Toshikuni Isozaki 《Nuclear Engineering and Design》1983,75(1):157-168
The analytical results of blowdown characteristics and thrust forces were compared with the experiments, which were performed as pipe whip and jet discharge tests under the PWR LOCA conditions. The blowdown thrust forces were obtained by Navier-Stokes momentum equation for a single-phase, homogeneous and separated two-phase flow, assuming critical pressure at the exit if a crifical flow condition was satisfied.The following results are obtained:
- 1. (1) The node-junction method is useful for both the analyses of the blowdown thrust force and of the water hammer phenomena.
- 2. (2) The Henry-Fauske model for subcooled critical flow is effective for the analysis of the maximum thrust force under the PWR LOCA conditions. The jet thrust parameter of the analysis and experiment is equal to 1.08.
- 3. (3) The thrust parameter of saturated blowdown has the same one with the value under pressurized condition when the stagnant pressure is chosen as the saturated one.
- 4. (4) The dominant terms of the blowdown thrust force in the momentum equation are the pressure and momentum terms except that the acceleration term has large contribution only just after the break.