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61.
CA Zeman MA Arcand JS Cantrell JG Skedros WZ Burkhead 《Canadian Metallurgical Quarterly》1998,6(6):337-348
The symptomatic rotator cuff-deficient, arthritic glenohumeral joint poses a complex problem for the orthopaedic surgeon. Surgical management can be facilitated by classifying the disorder in one of three diagnostic categories: (1) rotator cuff-tear arthropathy, (2) rheumatoid arthritic shoulder with cuff deficiency, or (3) degenerative arthritic (osteoarthritic) shoulder with cuff deficiency. If it is not possible to repair the cuff defect, surgical management may include prosthetic arthroplasty, with the recognition that only limited goals are attainable, particularly with respect to strength and active motion. Glenohumeral arthrodesis is a salvage procedure when other surgical measures have failed. Arthrodesis is also indicated in patients with deltoid muscle deficiency. Humeral hemiarthroplasty avoids the complications of glenoid loosening and is an attractive alternative to arthrodesis, resection arthroplasty, and total shoulder arthroplasty. The functionally intact coracoacromial arch should be preserved to reduce the risk of anterosuperior subluxation. Care should be taken not to "overstuff" the gleno-humeral joint with a prosthetic component. In cases of significant internal rotation contracture, subscapularis lengthening is necessary to restore anterior and posterior rotator cuff balance. If the less stringent criteria of Neer's "limited goals" rehabilitation are followed, approximately 80% to 90% of patients treated with humeral hemiarthroplasty can have satisfactory results. 相似文献
62.
JG Ray 《Canadian Metallurgical Quarterly》1998,53(7):450-455
Synthetic 1-deamino-8-D-arginine-vasopressin (DDAVP) is used in the management of diabetes insipidus (DI). We conducted a systematic literature review of DDAVP use during pregnancy, with particular attention to its safety for both mother and infant. Studies were identified through Ovid MEDLINE from 1976 to July 1997 using the combined terms "desmopressin," "DDAVP," and "pregnancy". Review articles and published letters were also explored. One hundred one articles were retrieved, of which 20 met all the inclusion criteria. Included in the 20 articles were 53 cases with the use of DDAVP for the management of DI. The therapeutic daily dose of DDAVP was approximately 29 micrograms intranasally (range 7.5-100 micrograms), with adequate DI control observed. Three of 14 women with sufficient information developed preeclampsia, a nonsignificant difference from the expected rate of 5 percent (the Fisher exact test, 2-P = .08). The mode of delivery was defined for 22 cases, with 16 uneventful vaginal births, and six cesarean delivery. There was no evidence of a drug interaction among the five women who received both DDAVP and intravenous oxytocin. Information was available on 49 live births born to DI mothers on DDAVP. The mean gestational age at delivery was 37.4 weeks (SD 1.3 weeks), with an estimated mean birth weight of 2963.8 gm (range 2000-4420 gm). Forty-three offspring were reported as healthy (event rate 87.8 percent; 95 percent CI 77.2-95.3 percent). Of the remaining six infants, one developed DI at 18 months of age; a second was under 2500 gm at birth, but survived; the third developed hypotonia and failure to thrive at 21 months, two others had Down syndrome; and the sixth died of severe cardiac anomalies. Similar data were seen among the 41 infants whose mothers had used DDAVP throughout pregnancy. In conclusion, DDAVP use during pregnancy seems to be safe for both mother and child. Delivery does not seem to be augmented by its use, nor are there likely any associated adverse neonatal effects. A large database of DDAVP use during pregnancy is needed to confirm these findings. 相似文献
63.
Bart F. Zalewski Robert L. Mullen 《Computer Methods in Applied Mechanics and Engineering》2009,198(37-40):2996-3005
In this work, point-wise discretization error is bounded via interval approach for the elasticity problem using interval boundary element formulation. The formulation allows for computation of the worst case bounds on the boundary values for the elasticity problem. From these bounds the worst case bounds on the true solution at any point in the domain of the system can be computed. Examples are presented to demonstrate the effectiveness of the treatment of local discretization error in elasticity problem via interval methods. 相似文献
64.
Current methods used clinically to assess myocardial perfusion are invasive and expensive. As the technology of ultrasound imaging improves, CE may provide a relatively inexpensive, noninvasive means of quantitating myocardial perfusion. Issues regarding stability of microbubble contrast agents must be studied more closely under physiologic conditions. As such, encapsulated microbubbles may provide more stability under physiologic pressures than free gas microbubbles. Introducing high concentrations of contrast, either by hyperconcentrating the contrast agent or by increasing the injection rate, may provide greater stability under physiologic conditions. Further, before quantitative statement of tissue perfusion can be made, the relationship between tracer concentration and system response must be established. Further, a "linear" postprocessing ultrasound setting does not eliminate this requirement as data must still undergo nonlinear transformation during log compression and time-gain compensation. Additionally, issues regarding "electronic thresholding" must be explored more extensively in vivo. Commercial ultrasound scanners, in their present form, may not offer adequate sensitivity for absolute quantitative studies. Further development of modified ultrasound systems may provide sufficient sensitivity for quantitative perfusion imaging. CE offers a potentially powerful tool in the clinical management of patients with ischemic heart disease. Conventional coronary angiography provides information on the size of a lesion, but accompanying tissue perfusion distal to the lesion cannot be determined. Doppler ultrasonography determines velocity of blood flow in large vessels but does not offer the potential to quantitate tissue perfusion. Clearly, CE has a place in the future of diagnostic imaging. The recent work of Ito et al. demonstrated the qualitative potential of CE in the identification of "areas at risk" in patients who had undergone thrombolysis or percutaneous transluminal coronary angioplasty after an acute myocardial infarction. With further improvement in the ultrasound imaging techniques and microbubble stability, CE may offer an inexpensive, noninvasive means of assessing myocardial perfusion. 相似文献
65.
We describe an assay system for measuring theophylline in 25 microliters of serum. The procedure involves extraction with a 95:5 mixture of chloroform:isopropanol containing beta-hydroxypropyltheophylline as internal standard, and reverse-phase chromatography on a 4 mm x 30 cm column containing "micron Bondapak C18." Theophylline and beta-hydroxypropyltheophylline are eluted with a 90:10 mixture of sodium acetate butter (20 mmoles/litre pH 4.0) and acetonitrile at a flow rate of 1.8 ml/min., are detected by their absorbance at 254 nm, and quantitated by measuring peak areas. Column temperature has not been found to be critical in this analysis. Each analysis requires 9 minutes of chromatography time with a total analysis time of 20 minutes. Analytical recoveries were found to be 71 to 75% for theophylline and 94% for beta-hydroxypropyltheophylline. This difference in recovery is corrected when determining the theophylline concentration in unknown samples. The method has good precision (coefficients of variation between 7.0% and 7.9% for therapeutic and toxic concentrations). The results obtained with this method compare favourably with results obtained by a published cation-exchange high-performance liquid chromatographic method. None of the metabolites of theophylline, common compounds related to theophylline in structure or drugs tested have been found to interfere with the analysis described. 相似文献
66.
Lateral suprasylvian cortex (LS) is an important source of visual projections to both the striatum and superior colliculus. Although these two LS efferent systems are likely to be involved in different aspects of visual processing, little is known about their functional properties. In the present experiments, 86 neurons in halothane-anesthetized, paralyzed cats were recorded along the posterior aspects of the medial and lateral banks of LS (PMLS and PLLS). Neurons were selected for analysis on the basis of antidromic activation from electrodes chronically implanted in the superior colliculus and caudate nucleus. The segregated nature of corticostriatal and corticotectal neurons was apparent; in no instance could a neuron be antidromically activated from both the superior colliculus and the caudate nucleus. Many common features were revealed between corticotectal and corticostriatal neurons; the majority of neurons in both populations were binocular and contralaterally dominant, showed similar responses to stationary flashed light, and expressed within-field spatial summation and surround inhibition. However, a number of information-processing features distinguished between corticotectal and corticostriatal neurons; the former were generally tuned to lower velocities than were the latter, and, for a given eccentricity in visual space, corticotectal neurons had smaller receptive fields than did corticostriatal neurons. Moreover, most corticotectal neurons displayed a marked preference for movements toward temporal visual space, whereas corticostriatal neurons revealed no specialization for a particular direction of movement. In addition, whereas corticotectal neurons were selective for receding stimuli, corticostriatal neurons were selective for approaching stimuli. The presence of these two corticofugal pathways is discussed in relation to their presumptive functional roles in the facilitation of attentive and orientation behaviors. 相似文献
67.
PW Roelvink A Lizonova JG Lee Y Li JM Bergelson RW Finberg DE Brough I Kovesdi TJ Wickham 《Canadian Metallurgical Quarterly》1998,72(10):7909-7915
Attachment of an adenovirus (Ad) to a cell is mediated by the capsid fiber protein. To date, only the cellular fiber receptor for subgroup C serotypes 2 and 5, the so-called coxsackievirus-adenovirus receptor (CAR) protein, has been identified and cloned. Previous data suggested that the fiber of the subgroup D serotype Ad9 also recognizes CAR, since Ad9 and Ad2 fiber knobs cross-blocked each other's cellular binding. Recombinant fiber knobs and 3H-labeled Ad virions from serotypes representing all six subgroups (A to F) were used to determine whether the knobs cross-blocked the binding of virions from different subgroups. With the exception of subgroup B, all subgroup representatives cross-competed, suggesting that they use CAR as a cellular fiber receptor as well. This result was confirmed by showing that CAR, produced in a soluble recombinant form (sCAR), bound to nitrocellulose-immobilized virions from the different subgroups except subgroup B. Similar results were found for blotted fiber knob proteins. The subgroup F virus Ad41 has both short and long fibers, but only the long fiber bound sCAR. The sCAR protein blocked the attachment of all virus serotypes that bound CAR. Moreover, CHO cells expressing human CAR, in contrast to untransformed CHO cells, all specifically bound the sCAR-binding serotypes. We conclude therefore that Ad serotypes from subgroups A, C, D, E, and F all use CAR as a cellular fiber receptor. 相似文献
68.
This study was undertaken to determine the relative effects of morphine and halothane anesthesia on coronary blood flow. Right heart bypass was instituted in 20 dogs by draining the vena cava blood into a cardiotomy reservoir and returning it to the main pulmonary artery. Coronary sinus drainage was measured by a right ventricular cannula. Group I (10 dogs) was sequentially given 0.5, 1, 1.5, 2.0, and 2.5% halothane. Group II (10 dogs) was given 1, 2, 3, 4, and 5 mg per kilogram of morphine intravenously. Arterial pressure, coronary sinus blood flow, cardiac output, arterial pH, PCO2, and PO2 were determined and repeated at each dose level of anesthesia and compared to the control values. Morphine significantly increased coronary flow at 3, 4, and 5 mg/kg without pressure adjustment and at 2 mg/kg after pressure adjustment. Coronary flow with halothane was unchanged from control values except for a decrease at 2.5%. Coronary flow was significantly greater with 3, 4, and 5 mg/kg of morphine than with 1.0 and 1.5% halothane. 相似文献
69.
Optical detection, ranging, and imaging of targets in turbid water is complicated by absorption and scattering. It has been shown that using a pulsed laser source with a range-gated receiver or an intensity modulated source with a coherent RF receiver can improve target contrast in turbid water. A blended approach using a modulated-pulse waveform has been previously suggested as a way to further improve target contrast. However only recently has a rugged and reliable laser source been developed that is capable of synthesizing such a waveform so that the effect of the underwater environment on the propagation of a modulated pulse can be studied. In this paper, we outline the motivation for the modulated-pulse (MP) concept, and experimentally evaluate different MP waveforms: single-tone MP and pseudorandom coded MP sequences. 相似文献
70.
C. A. Mullen T. J. Vaughan M. C. Voisin M. A. Brennan P. Layrolle L. M. McNamara 《Journal of the Royal Society Interface》2014,11(101)
Extracellular mechanical cues have been shown to have a profound effect on osteogenic cell behaviour. However, it is not known precisely how these cues alter intracellular mechanics to initiate changes in cell behaviour. In this study, a combination of in vitro culture of MC3T3-E1 cells and finite-element modelling was used to investigate the effects of passive differences in substrate stiffness on intracellular mechanics. Cells on collagen-based substrates were classified based on the presence of cell processes and the dimensions of various cellular features were quantified. Focal adhesion (FA) density was quantified from immunohistochemical staining, while cell and substrate stiffnesses were measured using a live-cell atomic force microscope. Computational models of cell morphologies were developed using an applied contraction of the cell body to simulate active cell contraction. The results showed that FA density is directly related to cell morphology, while the effect of substrate stiffness on internal cell tension was modulated by both cell morphology and FA density, as investigated by varying the number of adhesion sites present in each morphological model. We propose that the cells desire to achieve a homeostatic stress state may play a role in osteogenic cell differentiation in response to extracellular mechanical cues. 相似文献