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81.
ME Losada S Carbone B Szwarcfarb JA Moguilevsky 《Canadian Metallurgical Quarterly》1993,57(5):960-964
Amino acid concentration in the anterior preoptic area and medial basal hypothalamus was determined by HPLC in female rats: (1) at 16 (prepubertal) vs. 30 (peripubertal) days of age and (2) after N-methyl-D-aspartate (NMDA) or dizocilpine (MK-801) administration in both groups. 30-day-old rats had higher levels of aspartate (Asp; 24%), glutamate (Glu; 49%) and glycine (Gly; 44%) and lower levels of taurine (Tau; 43%) than 16-day-old rats. In 16-day-old rats, NMDA (30 mg/kg, s.c., 10 min) increased the Glut concentration (48%). This effect was prevented by MK-801 pretreatment (1 mg/kg, s.c., 1 h), which did not modify amino acid concentrations per se. In 30-day-old rats, NMDA treatment increased Glut (24%) and asp (42%) levels. MK-801 pretreatment abolished NMDA-induced changes and reduced Tau (26%) and Gly (30%) levels. MK-801 administration alone reduced the concentration of Glut (39%), Asp (54%), Tau (33%) and Gly (31%). It is concluded that both (1) the concentration of Asp, Glu, Gly and Tau and (2) the changes induced by NMDA receptor activation or blockade are different at 16 vs. 30 days of age. The existence of a tonic (positive) control on amino acid levels linked to the NMDA receptor which would be immature or absent at 16 days of age is suggested. 相似文献
82.
Ascorbic acid and glutathione (GSH) are antioxidants and free radical scavengers that provide the first line of defense against oxidative damage in the CNS. Using HPLC with electrochemical detection, we determined tissue contents of these antioxidants in brain and spinal cord in species with varying abilities to tolerate anoxia, including anoxia-tolerant pond and box turtles, moderately tolerant garter snakes, anoxia-intolerant clawed frogs (Xenopus laevis), and intolerant Long-Evans hooded rats. These data were compared with ascorbate and GSH levels in selected regions of guinea pig CNS, human cortex, and values from the literature. Ascorbate levels in turtles were typically 100% higher than those in rat. Cortex, olfactory bulb, and dorsal ventricular ridge had the highest content in turtle, 5-6 mumol g-1 of tissue wet weight, which was twice that in rat cortex (2.82 +/- 0.05 mumol g-1) and threefold greater than in guinea pig cortex (1.71 +/- 0.03 mumol g-1). Regionally distinct levels (2-4 mumol g-1) were found in turtle cerebellum, optic lobe, brainstem, and spinal cord, with a decreasing anterior-to-posterior gradient. Ascorbate was lowest in white matter (optic nerve) in each species. Snake cortex and brainstem had significantly higher ascorbate levels than in rat or guinea pig, although other regions had comparable or lower levels. Frog ascorbate was generally in an intermediate range between that in rat and guinea pig. In contrast to ascorbate, GSH levels in anoxia-tolerant turtles, 2-3 mumol g-1 of tissue wet weight, were similar to those in mammalian or amphibian brain, with no consistent pattern associated with anoxia tolerance. GSH levels in pond turtle CNS were significantly higher (by 10-20%) than in rat for several regions but were generally lower than in guinea pig or frog. GSH in box turtle and snake CNS were the same or lower than in rat or guinea pig. The distribution GSH in the CNS also had a decreasing anterior-to-posterior gradient but with less variability than ascorbate: levels were similar in optic nerve, brainstem, and spinal cord. The paradoxically high levels of ascorbate in turtle brain, which has a lower rate of oxidative metabolism than mammalian, suggest that ascorbate is an essential cerebral antioxidant. High levels may have evolved to protect cells from oxidative damage when aerobic metabolism resumes after a hypoxic dive. 相似文献
83.
We report a case of Wernicke encephalopathy in which the only sign of acute disease was enhancement of the mamillary bodies. This case demonstrates the utility of gadolinium enhancement at MR imaging as a means of diagnosing or confirming the syndrome of Wernicke encephalopathy even in the absence of atrophy or T2 abnormalities within the diencephalon and mesencephalon. 相似文献
84.
The purpose of the present study was to test a model of spatial-semantic display processing by comparing the aided and unaided recall of information presented in a node-link format (knowledge map) to the aided and unaided recall of information presented in a text format. Structural icons of the knowledge map and text with the verbiage removed were used to aid retrieval in some conditions. Participants were randomly assigned to one of eight groups formed by the complete crossing of three factors: knowledge map versus text, structural icon at recall versus no structural icon at recall, and immediate versus delayed recall. Knowledge map groups outperformed text groups on essay tests and they more accurately remembered where information was located within the materials. Both knowledge map and text icon-aided recall groups had significantly better performance than the no icon, unaided recall groups (particularly on main ideas). 相似文献
85.
86.
JM Lablanche EP McFadden N Meneveau JR Lusson B Bertrand JP Metzger V Legrand G Grollier C Macaya B de Bruyne A Vahanian A Grentzinger C Masquet JE Wolf G Tobelem S Fontecave A Vacheron P d'Azemar ME Bertrand 《Canadian Metallurgical Quarterly》1997,96(10):3396-3402
BACKGROUND: Experimental studies suggest that the antiproliferative effect of heparin after arterial injury is maximized by pretreatment. No previous studies of restenosis have used a pretreatment strategy. We designed this study to determine whether treatment with nadroparin, a low-molecular-weight heparin, started 3 days before the procedure and continued for 3 months, affected angiographic restenosis or clinical outcome after coronary angioplasty. METHODS AND RESULTS: In a prospective multicenter, double-blind, randomized trial, elective coronary angioplasty was performed on 354 patients who were treated with daily subcutaneous nadroparin (0.6 mL of 10,250 anti-Xa IU/mL) or placebo injections started 3 days before angioplasty and continued for 3 months. Angiography was performed just before and immediately after angioplasty and at follow-up. The primary study end point was angiographic restenosis, assessed by quantitative coronary angiography 3 months after balloon angioplasty. Clinical follow-up was continued up to 6 months. Clinical and procedural variables and the occurrence of periprocedural complications did not differ between groups. At angiographic follow-up, the mean minimal lumen diameter and the mean residual stenosis in the nadroparin group (1.37+/-0.66 mm, 51.9+/-21.0%) did not differ from the corresponding values in the control group (1.48+/-0.59 mm, 48.8+/-18.9%). Combined major cardiac-related clinical events (death, myocardial infarction, target lesion revascularization) did not differ between groups (30.3% versus 29.6%). CONCLUSIONS: Pretreatment with the low-molecular-weight heparin nadroparin continued for 3 months after balloon angioplasty had no beneficial effect on angiographic restenosis or on adverse clinical outcomes. 相似文献
87.
88.
89.
Immunoglobulin A levels in southern elephant seal (Mirounga leonina) milk during the suckling period
ME Marquez NH Slobodianik PA Ronayne de Ferrer AR Carlini DF Vergani GA Daneri 《Canadian Metallurgical Quarterly》1995,112(3):569-572
Immunoglobulin A (IgA) levels in milk samples from southern elephant seals at King George Island, Antarctica are reported. IgA levels were determined throughout the suckling period (approximately 23 days). The IgA concentration in southern elephant seal milk was lower than in other mammals and, unlike most mammalian milk, was not high during early lactation. There was not a definite pattern in IgA levels, which fluctuated within narrow limits throughout the suckling period (mean +/- SD, 30.81 +/- 6.38 mg IgA/100 g milk). If IgG was present, its level was too low to be detected by the method used. This is the first evidence in Southern elephant seal of the possibility of transmission of passive immunity after birth involving secretion of IgA in the milk. 相似文献
90.
K Kohno JA Palha K Miyakawa MJ Saraiva S Ito T Mabuchi WS Blaner H Iijima S Tsukahara V Episkopou ME Gottesman K Shimada K Takahashi K Yamamura S Maeda 《Canadian Metallurgical Quarterly》1997,150(4):1497-1508
Amyloid fibrils derived from the Japanese, Portuguese, and Swedish types of familial amyloidotic polyneuropathy all consist of a variant transthyretin (TTR) with a substitution of methionine for valine at position 30 (TTR Met 30). In an attempt to establish an animal model of TTR Met-30-associated homozygous familial amyloidotic polyneuropathy and to study the structural and functional properties of human TTR Met 30, we generated a mouse line carrying a null mutation at the endogenous ttr locus (ttr-/-) and the human mutant ttr gene (6.0-hMet 30) as a transgene. In these mice, human TTR Met-30-derived amyloid deposits were first observed in the esophagus and stomach when the mice were 11 months of age. With advancing age, amyloid deposits extended to various other tissues. Because no significant difference was detected in the onset, progression, and tissue distribution of amyloid deposition between the ttr-/- and ttr+/+ transgenic mice expressing 6.0-hMet 30, endogenous normal mouse TTR probably does not affect the deposition of human TTR Met-30-derived amyloid in mice. TTR is a tetramer composed of four identical subunits that binds thyroxine (T4) and plasma retinol-binding protein. The introduction of 6.0-hMet 30 into the ttr-/- mice significantly increased their depressed serum levels of T4 and retinol-binding protein, suggesting that human TTR Met 30 binds T4 and retinol-binding protein in vivo. The T4-binding ability of human TTR Met 30 was confirmed by the analysis of T4-binding proteins in the sera of ttr-/- transgenic mice expressing 6.0-hMet 30. The T4-binding studies also demonstrated the presence of hybrid tetramers between mouse and human TTR subunits in the ttr+/+ transgenic mice expressing 6.0-hMet 30. 相似文献