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161.
In the real world, there is an interaction between pest, plant and pesticide that greatly affects the kinds and amounts of potentially toxic and allergenic chemicals that we eat. These interactions are virtually ignored in food safety regulation. Exposure to potentially toxic chemicals from crop foods comes from three principle sources: fungal toxin contamination, natural toxicants and allergens of the plant itself (‘self-defense’ chemistries), and from synthetic pesticide residues. To be effective, these ‘self-defense’ chemistries are often potent toxicants. When tested similarly to synthetic pesticides, plant self-defense chemistries are often toxic to genes, cause cancer, cause reproductive problems, cause birth defects, and the like. Our exposure to self-defense chemicals and allergenic proteins of plants is variable, and depends on growing conditions, which kind of crop, which variety of crop, selection for natural resistance to insects and fungi, the plant’s dynamic response to environmental stressors including insects and fungi, and possible mitigation of insect and fungal stress by use of synthetic or biotechnology pesticides, and post-harvest management. The ratio of self-defense chemistries to synthetic pesticides in our diets has been estimated at greater than 10,000 to 1 (Ames, 1983; Beier and Nigg, 2001). Almost the entire focus of society and regulatory agencies is to manage the 1 part in 10000. Obviously, this partitioning of resources is not scientifically rational. The plant world is interactive, and this dynamic must be managed to improve food safety.  相似文献   
162.
Interface engineering of short-period Ni/V multilayer X-ray mirrors   总被引:1,自引:0,他引:1  
Low-energy ion-assisted magnetron sputter deposition has been used for the synthesis of highly reflective Ni/V multilayer soft X-ray mirrors. A low ion energy and a high ion-to-metal flux ratio were employed in order to stimulate the adatom mobility while minimizing ion-induced intermixing at the interfaces. An analytic model, based on the binary collision approximation, was used in order to gain insight into low-energy ion–surface interactions as a function of ion energy and ion-to-metal flux ratio. The model predicted a favorable region in the ion energy-flux parameter space where only surface atomic displacements are stimulated during growth of Ni and V for multilayers. For a series of Ni/V multilayer mirrors with multilayer periods about Λ = 1.2 nm, grown with a continuous ion assistance using energies in the range 7–36 eV and with ion-to-metal flux ratios ΦNi = 4.7 and ΦV=20.9, specular and diffuse X-ray scattering analyses revealed that ion energies of 27–31 eV produced the best trade-off between reduced interfacial roughness and intermixing. However, it was also concluded that an interface mixing of about ± 1 atomic distance is unavoidable when a continuous flux of assisting ions is used.

To overcome this limitation, a sophisticated interface engineering technique was employed, where the first 0.3 nm of each layer was grown with a high-flux low-energy ion assistance and the remaining part was grown with a slightly higher ion energy. This method was demonstrated to largely eliminate the intermixing while maintaining the smoothening effect of ion assistance. Two Ni/V multilayer soft X-ray mirror structures, one with 500 periods designed for near-normal incidence and one 150 periods reflecting polarizer at the Brewster angle, were grown utilizing the interface engineering concept. Both the near-normal incidence reflectivity as well as polarizability were improved by a factor of 2 as compared to previously reported data for an X-ray energy of E = 511 eV.  相似文献   

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164.
Patients at a high risk for sudden cardiac death (SCD) without previous history of cardiovascular disease remain a challenge to identify. Atherosclerosis and prothrombotic states involve inflammation and non-cardiac tissue damage that may play active roles in SCD development. Therefore, we hypothesized that circulating proteins implicated in inflammation and tissue damage are linked to the future risk of SCD. We conducted a prospective nested case–control study of SCD cases with verified myocardial infarction (N = 224) and matched controls without myocardial infarction (N = 224), aged 60 ± 10 years time and median time to event was 8 years. Protein concentrations (N = 122) were measured using a proximity extension immunoassay. The analyses revealed 14 proteins significantly associated with an increased risk of SCD, from which two remained significant after adjusting for smoking status, systolic blood pressure, BMI, cholesterol, and glucose levels. We identified leukotriene A4 hydrolase (LTA4H, odds ratio 1.80, corrected confidence interval (CIcorr) 1.02–3.17) and hepatocyte growth factor (HGF; odds ratio 1.81, CIcorr 1.06–3.11) as independent risk markers of SCD. Elevated LTA4H may reflect increased systemic and pulmonary neutrophilic inflammatory processes that can contribute to atherosclerotic plaque instability. Increased HGF levels are linked to obesity-related metabolic disturbances that are more prevalent in SCD cases than the controls.  相似文献   
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166.
Due to the considerable high bio-compatibility, calcium phosphate nanoparticles are widely used in biomedical applications. This study proposes a novel strategy for low-cost manufacturing calcium phosphate nanoporous spheres. The controlled reaction only took less than five minutes, when using Baltic seawater with the dissolved calcium concentration of 2.2?mM as the calcium resources. Porous nanospheres were obtained, with spheres ranging from 50 to 130?nm. The obtained nanospheres possess high drug-loading capacity and exhibit sustained release and pH-dependent properties. In addition, this method provides a general efficient strategy to synthesize other low-cost inorganic nanospheres from seawater.  相似文献   
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168.
A rigid-body model of a finger interacting with a trackball is considered. The proposed system is a suitable candidate for studying trajectory generation when interaction plays an important role, such as in assembly and manipulation tasks. The mathematical model consists of a ball with a spherical joint constraint, a finger with three degrees of freedom, and the Coulomb friction model. From first principles, we derive a hybrid, high-index differential-algebraic equation for modeling the system dynamics, which is used for both simulation and finding optimal trajectories. For this problem, task planning, path planning, and trajectory generation are strongly interrelated, which makes using an integrated approach to trajectory generation inevitable. Moreover, the trajectory generation algorithm has to handle a number of important features, e.g., unilateral and non-holonomic constraints.  相似文献   
169.
We wanted to provide details on the psychometric documentation of the Swedish version of the Women's Health Questionnaire (WHQ), a patient based measure of postmenopausal complaints. The results of two clinical trials in Sweden in which the WHQ had been used as one out of several measurement tools were used to document the reliability, the validity and the responsiveness to change of the WHQ. More than 350 women suffering from postmenopausal complaints were included in the two trials. A factor analysis, using the baseline values of all women in each study, showed that the Swedish version of the WHQ was very close to the English original. The internal consistency reliability was excellent. The clinical validity was confirmed by a significant correlation between change in E2 levels and change in the WHQ during estrogen therapy. A high construct validity was established by the agreement between the WHQ and other quality of life scales. For use in clinical trials the WHQ was sensitive to treatment-induced changes, and added important information to the clinical effect variables.  相似文献   
170.
The study was undertaken to determine if the levels of vesicular zinc in neuronal terminals would decrease in response to focal brain ischemia. The middle cerebral artery was occluded distal to the striatal branches in male spontaneously hypertensive rats. At 7, 15, 30, 45, 60, 90, 120 min; 3, 6, 12, 24, 48 h and 7 days later the animals were sacrificed and the brains were stained for zinc-sulfides, cell bodies and AChE-positive cholinergic fibers. The density of zinc positive terminals significantly decreased in the neocortical ischemic zone 7 min after middle cerebral artery occlusion (MCAO). In the neocortical layers II and III most zinc positive neuronal terminals disappeared at 7 min after MCAO whereas the zinc positive terminals in layers V and VI remained positive at least 2 h. Beginning at 1 h after MCAO and progressing to 24 h a significant decrease in the density of zinc positive terminals was observed in the dorsolateral striatum, and ventrobasal thalamic nucleus, both major projection areas of the sensorimotor cortex. The disappearance of zinc positive neuronal terminals in the ischemic neocortex and related areas, is most likely due to a neuronal release of vesicular zinc in response to hypoxia. The high extracellular concentration of zinc is thought to be both neuroprotective by blocking the NMDA receptor and neurotoxic by activating neuronal influx of Ca2+ through voltage gated calcium channels. It seems evident that the latter effect of zinc is contributing to the neuronal death in focal brain ischemia.  相似文献   
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