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51.
Oestradiol regulates reproductive physiology and cardiovascular health in women. In the endometrium of ovariectomized ewes, previous work demonstrated that a single dose of oestradiol (50 microg) up-regulates oestrogen receptor-alpha (ER) and progesterone receptor (PR) gene expression within 24 h. Here we compared responses to different doses of oestradiol and different dosing regimens in two diverse tissues: endometrium and liver. ER, c-fos, cyclophilin and glyceraldehyde phosphate dehydrogenase (GAPDH) mRNA concentrations were analyzed on replicate RNA slot blots in both tissues, while PR and apolipoprotein AI (apo AI) mRNA concentrations were only analyzed in endometrium or liver, respectively. Along with ER mRNA, oestradiol strongly up-regulated GAPDH and cyclophilin mRNA concentrations in endometrium. In liver, however, oestradiol down-regulated them, along with apo AI mRNA. Responses to different doses and dose regimens, including repeated 50 microg doses, were similar to those evoked by a single 50 microg dose of oestradiol. Thus, oestradiol appears to have all-or-none effects which include up-regulation of ER, cyclophilin and GAPDH gene expression in endometrium and down-regulation of ER, apo AI, cyclophilin and GAPDH gene expression in liver. These results illustrate the sharp contrast between two mammalian tissues in their responses to physiological levels of oestradiol. 相似文献
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AA al-Jafari MA Kamal NH Greig AS Alhomida ER Perry 《Canadian Metallurgical Quarterly》1998,248(1):180-185
The elastic properties of carotid arteries of spontaneously hypertensive rats (SHR) and normotensive controls (Wistar-Kyoto rats [WKY]) were examined in vivo, in situ, and in vitro. The changes of internal diameter were measured with a high-resolution A-mode echo-tracking device simultaneously with the intra-arterial pressure at the carotid. The internal diameter at mean arterial blood pressure (MBP) was substantially smaller in vitro than in vivo in SHR (-33.8%) and WKY (-48.3%). The arterial distensibility was lower in vitro in all arteries compared with in vivo conditions (SHR, -30.1%; WKY, -60.4%; at MBP) despite a reduced incremental elastic modulus in vitro (SHR, -56.9%; WKY, -45.1%; at MBP). However, the in vitro and in vivo measurements show consistent elastic behavior of the carotid arteries between both strains of rats. Carotid arteries from WKY were also examined in situ. Although no significant reduction in internal diameter could be observed in situ, distensibility was dramatically decreased (-87% at MBP). These results emphasize the importance of considering the original vascular geometry when determining elastic properties of arteries. We conclude that experimental conditions are likely to be a critical determinant for the assessment of the mechanical properties of conduit vessels. 相似文献
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P Mamunes PE Prince NH Thornton PA Hunt ES Hitchcock 《Canadian Metallurgical Quarterly》1976,57(5):675-680
An analysis was made of the obstetric history of 1,360 patients who were delivered in 1971. It involved 3,185 pregnancies. The aim of the study was to evaluate the risk of spontaneous termination of the pregnancy, worked out from its demographic aspect. Several ideas are worthy of consideration. The risk of spontaneous intra-uterine death is cumulative, sharply increased by a repetition of such cessation of pregnancy. The same patients often undergo intentional abortion repeatedly. The respective risks of spontaneous and provoked interruption of pregnancy have been studied in greater detail as a function of parity. 相似文献
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AE El Sherbeiny MA El Ansari MA Nawwar NH El Sayed 《Canadian Metallurgical Quarterly》1977,32(2):165-170
In this study of interactions occurring within the heart, isolated superfused strips of rabbit atria, containing the sinoatrial (s.a.) node, were subjected to sinusoidal subthreshold current pulses of varied frequencies and intensities. A.C. current from an R.C. oscillator was applied through a Grass stimulation isolation unit, push-pull connection, and non-polarizing (Ag-AgCl-KCl-Tyrode Agar-Agar) electrodes. A Grass polygraph and tachometer were used to record the applied pulses and nodal firing rates; simultaneous magnetic tape recordings were obtained and used for data analysis. Suction electrode recordings and oscilloscope displays were used to determine how the cyclic impulses affected cellular activity. The s.a. nodal rhythm was modified by subthreshold A.C. current applications; when frequencies were low, firing rates of the node were modulated by the A.C. and mean rates were reduced. As frequencies were progressively increased, slow waxings and wanings in heart rate were produced. These periodic fluctuations were not readily correlated with either the A.C. frequency nor the intrinsic nodal rate, but were representative of the difference between the two. As applied current frequency neared the pacemaker's intrinsic rate, a synchronization occurred and the discharges locked in at a specific phase of the applied current alternation. This synchronization maintained during slight further increases in A.C. frequency but above a critical rate this relationship broke down and the waxing and wanings in frequency of pacemaker rate again developed. It was concluded that pacemaker action of the s.a. node is effected by integration of cellular activity through electron coupling. 相似文献
59.
F Jónsson P Madsen LG J?rgensen M Lunding NH Secher 《Canadian Metallurgical Quarterly》1996,158(44):6256-6259
Indices of fluid balance were evaluated during and after aortic surgery in 16 consecutive patients. Thoracic electrical impedance (TI), heart rate (HR), central venous (CVP), pulmonary artery mean (PAMP), pulmonary wedge (PWP) and mean arterial (MAP) pressures as well as fourteen arterial and venous blood gas variables were followed. Consistent with a reduction of TI during the operation, fluid balance was in excess, and it remained elevated on the first postoperative morning. The HR, MAP and PWP remained stable, while CVP and PAMP decreased. Of the determined variables only TI revealed a meaningful correlation to fluid balance (rho = -0.41; p < 0.01). The results indicate that while central venous and pulmonary artery mean pressures gave the impression of a volume deficit, the positive fluid balance was mirrored by thoracic electrical impedance. 相似文献
60.
Jongsoo Jurng Nahmkeon Hur Kwang Ho Kim Chun Sik Lee 《Journal of Mechanical Science and Technology》1993,7(4):312-319
A numerical simulation is carried out to analyze the flow field of cooling air through the radiator and engine compartment. In order to consider the strong effect of the suction-type flow by the cooling fan at engine idling condition, a potential flow analysis is attempted by the assumption of a line sink located at the position of the cooling fan. The governing equations for steady two-dimensional, incompressible, turbulent flow are solved with the two-equationk-ε model for turbulence. The velocity profiles in the underhood engine compartment and around the front-end of a real vehicle are measured to compare with the numerical results. The agreement between the numerical and experimental results is fairly good. It is concluded that a two-dimensional computation is a fast and efficient tool for predicting the effect of front-end design on the cooling air flow through the radiator. 相似文献