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111.
Schwartz Sonia; Hoyte Joel; James Thea; Conoscenti Lauren; Johnson Renee; Liebschutz Jane 《Canadian Metallurgical Quarterly》2010,2(1):54
A dearth of literature exists on barriers to conducting research with Black male victims of community violence, despite the need for evidence-based postinjury interventions. This study used qualitative data from a cross-sectional interview study (n = 16) and a pilot intervention study (n = 11) conducted in Boston, MA to identify challenges and facilitators to conducting research with Black male victims of community violence, particularly with regard to recruitment and maintenance of a study sample. Qualitative methods, including Grounded Theory and ethnography, were used to analyze the data. Challenges included a fear of police involvement, an impression of “snitching” when disclosing personal information, mistrust of research motives, suspicion of the informed consent process, the emotional impact of the trauma itself, and logistical issues. Facilitators to research included monetary incentives and motivation to help oneself and others. Participant recommendations on recruitment methods relating to approach and timing are provided. Findings from this study may assist in the planning of research studies for Black male victims of community violence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
112.
Excessive frictional loading to the skin often results in the formation of blisters, due to the transmission of shear loading
to the interfaces between dermal cell strata. The consequences of blistering range from mild discomfort to serious infection.
In some patients, such as those disposed to epidermolysis bullosa or neuropathic diabetes, blisters can severely degrade life
quality. Investigation of environmental and application parameters that affect blister formation has occurred primarily as
a qualitative, observational pursuit on human subjects, which has often led to confounding of data and lack of repeatability.
The authors have developed a Synthetic Skin Simulant Platform (3SP) that reproduces the mechanical behavior of human skin
when exposed to tribological loading. The platform is an assembled construct of bonded elastomeric layers that act as surrogates
for the epidermis, basement membrane, dermis, and subdermal structure. Epidermal (top layer) materials are typically silicone
or polyurethane films with a friction coefficient akin to human skin, while sublayers display mechanical properties similar
to their anatomical analogs. Blistering is evident optically by examining the separation voids formed after applying shear
loads to the epidermal layer. The 3SP has been used in a two-axis pin-on-flat tribometer with a stainless steel indenter to
study the normal load and friction coefficients encountered at the onset of frictional blistering. The 3SP allows for modulation
of friction coefficient, interfacial adhesion strength, and subdermal stiffness for investigation of blistering damage to
various anatomical sites. Experimental results have been compared to human test data and have shown that the 3SP provides
the potential to make significant advances with respect to skin tribology research. 相似文献
113.
REDUCED‐ORDER MODELS FOR FEEDBACK STABILIZATION OF LINEAR SYSTEMS WITH A SINGULAR PERTURBATION MODEL
The problem of output feedback stabilization of linear systems based on a reduced‐order model is addressed in this paper. New reduced‐order models are proposed for the output feedback design of linear systems with a singular perturbation model. An output feedback controller with a zero steady‐state gain matrix is proposed for stabilizing this kind of system. It is shown that with the proposed controller the reduced‐order model based feedback design can guarantee the actual closed‐loop stability for the sufficiently small perturbation parameter. This approach can overcome the difficulties in the existing design method using the so‐called zeroth‐order approximation model, whose validity is highly dependent on the value of the perturbation parameter. 相似文献
114.
115.
The effect of three storage temperatures (0, -9 and -18 degrees C) of the kiwi-fruit pulp reduced pressure concentrate, by a period of 3 months, in the physical (soluble solids, water activity, consistency and color), chemistry (pH, acidity, ascorbic acid, chlorophyll and pheophytin) and sensorial (appearance, aroma, acidity, sweetness, color and flavor) characteristics were studied. The greater deterioration was produced in the stored pulp to 0 degree C, while to -9 degrees C there is no significative differences, on the other hand, the kiwi-fruit pulp stored to -18 degrees C maintained large part of the original characteristics. It was observed that while the temperature and storage time increased, vitamin C and chlorophyll contents decreased, varying significantly consistency, color and appearance of product. The rest of the analyzed variables did not present significative differences during storage. 相似文献
116.
117.
Jurkat T cells undergo rapid apoptosis upon stimulation of the Fas/APO-1 (CD95) receptor. We examined the role of the mitogen-activated protein kinase (MAPK) cascade as a negative regulator of Fas-mediated apoptosis. To this end, we used both physiologic and artificial activators of MAPK, all of which activate MAPK by distinct routes. MAPK activity could be efficiently elevated by two T cell mitogens, the lectin PHA and an agonistic Ab to the T cell receptor complex as well as by the type 1 and 2A phosphatase inhibitor, calyculin A, and the protein kinase C-activating phorbol ester, tetradecanoyl phorbol acetate. All these treatments were effective in preventing the characteristic early and late features of Fas-mediated apoptosis, including activation of caspases. Our results indicate that the elevated MAPK activities intervene upstream of caspase activation. The degree of MAPK activation by the different stimuli used in our study corresponds well to their potency to inhibit apoptosis, indicating that MAPK activation serves as an efficient modulator of Fas-mediated apoptosis. The role of MAPK in modulation of Fas-mediated apoptosis was further corroborated by transient transfection with constitutively active MAPK kinase, resulting in complete inhibition of the Fas response, whereas transfection with a dominant negative form of MAPK kinase had no effect. Furthermore, the apoptosis inhibitory effect of the MAPK activators could be abolished by the specific MAPK kinase inhibitor PD 098059. Modulation of Fas responses by MAPK signaling may determine the persistence of an immune response and may explain the insensitivity of recently activated T cells to Fas receptor stimulation. 相似文献
118.
119.
W. O. Soboyejo F. Ye D. S. Schwartz 《Metallurgical and Materials Transactions A》1996,27(8):2263-2273
Fatigue and fracture mechanisms in Nb fiber-reinforced MoSi2 composites are elucidated in this article. The effects of fiber diameter on fracture and crack-tip shielding mechanisms are
discussed after a review of micromechanical models which are applied to the prediction of residual stress levels, toughening,
and microcracking phenomena. Toughening is shown to occur by a combination of crack bridging and crack-tip blunting under
monotonic and cyclic loading. However, the observed failure mechanisms are different under monotonic and cyclic loading. Composites
with smaller (250-μm) fiber diameters are shown to have better fatigue resistance and lower fracture toughness than composites
with larger (750-μm) fiber diameters. The occurrence of slower fatigue crack growth rates in the composites reinforced with
smaller diameter Nb fibers is rationalized by assessing the combined effects of fiber spacing and interfacial crack growth
on the average crack growth rates within the composites. 相似文献
120.
Friedman Michael A.; Schwartz Marlene B.; Brownell Kelly D. 《Canadian Metallurgical Quarterly》1998,66(4):646
Two measures of weight cycling and indexes of psychological functioning were examined in a large sample of dieters. History of weight cycling was assessed to include number of dieting attempts, total lifetime weight lost and regained, and number of weight cycles over 20 lb (9.1 kg). Experience of weight cycling measured perception of being a yo-yo dieter and perceived success at maintaining past weight losses. Experience was more strongly related than history to all psychological measures. Further, when controlling for the effects of age, body mass index, and experience, the relation between history and the psychological variables was nonsignificant. This finding suggests that an individual's perception of being a weight cycler may be more related to psychological problems than the actual number of pounds lost and regained over dine. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献