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131.
The suitability of enzyme immunoassay (EIA) as a method of analysis for 2,4-D, atrazine and metolachlor contamination in water samples was determined by comparing EIA results to gas chromatography (GC) results. The comparison of EIA and GC results yielded a correlation coefficient of 0.92, 0.98 and 0.92 for 2,4-D, atrazine and metolachlor, respectively. EIA was used to monitor seasonal trends in the concentrations of 2,4-D, atrazine and metolachlor in surface water and precipitation throughout the province of Ontario, Canada. 2,4-D was detected in excess of 4 micrograms/L in urban creeks during the period of application. Concentrations of 43 and 9 micrograms/L of atrazine and metolachlor, respectively, were detected during the field application period in surface water samples from the Kintore Creek watershed. The levels of 2,4-D, atrazine and metolachlor detected exceeded the Canadian Water Quality Guidelines for the protection of fresh water aquatic life. Concentrations as high as 445 and 322 ng/L of atrazine and metolachlor, respectively, were detected in precipitation samples collected from 17 locations in Ontario during the herbicide application period. The EIA was shown to be qualitatively and quantitatively comparable to GC analysis. 相似文献
132.
133.
SI Kim N Stange-Thomann O Martins KW Hong D S?ll TD Fox 《Canadian Metallurgical Quarterly》1997,179(17):5625-5627
A novel Bacillus gene was isolated and characterized. It encodes a homolog of Saccharomyces cerevisiae Pet112p, a protein that has no characterized relative and is dispensable for cell viability but required for mitochondrial translation. Expression of the Bacillus protein in yeast, modified to ensure mitochondrial targeting, partially complemented the phenotype of the pet112-1 mutation, demonstrating a high degree of evolutionary conservation for this as yet unidentified component of translation. 相似文献
134.
MM Kattar WJ Kupsky RK Shimoyama TD Vo MW Olson GR Bargar FH Sarkar 《Canadian Metallurgical Quarterly》1997,28(10):1166-1179
In malignant gliomas, the characteristically heterogeneous features and frequent diffuse spread within the brain have raised the question of whether malignant gliomas arise monoclonally from a single precursor cell or polyclonally from multiple transformed cells forming confluent clones. Although monoclonality has been shown in surgically resected tissues, these may not include the full spectrum of patterns seen on autopsy material. Little is known about the clonality of low-grade gliomas from which malignant gliomas may sometimes arise. We sought to investigate the clonality of low-grade and malignant gliomas by using and comparing surgical and autopsy material with a Polymerase chain reaction (PCR)-based assay for nonrandom X chromosome inactivation. For that, purpose, archival surgical and autopsy material from 15 female patients (group A) (age 4 to 73 years; median, 45) with malignant gliomas (12 glioblastomas, one gliosarcoma, one anaplastic oligoastrocytoma, one gliomatosis cerebri), surgical material only from 21 female patients (group S) (age 6 to 78 years; median, 60) with low-grade and malignant gliomas (four low-grade astrocytomas, three oligoastrocytomas, two anaplastic astrocytomas, one gemistocytic astrocytoma, four oligodendrogliomas, seven glioblastomas) were analyzed. In group A, representative areas (mean = 5/patient; median = 7) were microdissected from tissue sections and assayed by PCR amplification of a highly polymorphic microsatellite marker locus of the human androgen receptor gene (HUMARA) in the presence of alpha32P with and without predigestion with a methylation-sensitive restriction enzyme (HhaI). Products were resolved by denaturing gel electrophoresis and autoradiographed. In group S, selected tumor areas were used for the assay. Each patient's normal brain tissue was used for control. The band intensity of alleles were measured by densitometric scanning. In group A, 13 of 15 cases were informative (heterozygous). The same pattern of nonrandom X chromosome inactivation was present in all areas of solid dense and moderate tumor infiltration in eight including all components of the gliosarcoma. Two of eight also showed focal loss of heterozygosity (LOH). One of 13 presented global LOH. Two of 13 showed microsatellite instability, one of which in a patient with Turcot syndrome, the other in gliomatosis cerebri. Opposite skewing patterns were seen in distant areas of gliomatosis cerebri consistent with oligoclonal derivation. Clonality remained indeterminate in one glioblastoma and in the anaplastic oligoastrocytoma because of skewed lyonization in the normal control. In group S, 19 of 21 cases were informative. Fifteen of 19 were monoclonal (four low-grade astrocytomas, one anaplastic astrocytoma, one gemistocytic astrocytoma, two oligodendrogliomas, one oligoastrocytoma, six glioblastomas). Four of 19 were indeterminate. We conclude that (1) Low-grade and malignant gliomas are usually monoclonal tumors, and extensively infiltrating tumors must result from migration of tumor cells (2) Gliomatosis cerebri may initiate as an oligoclonal process or result from collision gliomas (3) Biphasic gliomas likely arise from a single precursor cell. (4) LOH at the HUMARA locus is probably related to partial or complete deletion of an X-chromosome, which occurs in malignant gliomas during clonal evolution. 相似文献
135.
AB Swanson G de Groot Swanson DH DeHeer TD Pierce K Randall JM Smith CC Van Gorp 《Canadian Metallurgical Quarterly》1997,(342):46-58
In 1984, in an effort to address the silicone wear particle problem, titanium implants were developed for the scaphoid, lunate, and trapeziometacarpal joint. The design of these implants closely resembled their silicone counterparts, though some modifications were made to accommodate the properties of unalloyed titanium and enhance their stability. Carpal bone implants act as articulating spacers to help maintain the relationship of adjacent carpal bones after local resection procedures. Their use allows carpal stabilization procedures and provides functional mobility with good strength and pain relief. Their surgical application began in 1985. The 10-year clinical experience seems very promising to date. 相似文献
136.
Real-world objects are complex, containing information at multiple orientations and spatial scales. It is well established that at initial cortical stages of processing, local information about an image is separately represented at multiple spatial scales. However, it is not yet established how these early representations are later integrated across scale to signal useful information about complex stimulus features, such as edges and textures. In the studies reported here, we investigate the scale-integration processes involved in distinguishing among complex patterns. We use a concurrent-response paradigm in which observers simultaneously judge two components of compound gratings that differ widely in spatial frequency. In different experiments, each component takes one of two slightly different values along the dimensions of spatial frequency, contrast, or orientation. Using analyses developed within the framework of a multivariate extension of signal-detection theory, we ask how information about the frequency, contrast, or orientation of the components is or is not integrated across the two grating components. Our techniques permit us to isolate and identify interactions due to excitatory or inhibitory processes from effects due to noise, and to separately assess any attentional limitations that might occur in processing. Results indicate that orientation information is fully integrated across spatial scales within a limited orientation band and that decisions are based entirely on the summed information. Information about spatial frequency and contrast is not summed over spatial scale; cross-scale results show sensory independence. However, our results suggest that observers cannot simultaneously use information about frequency or contrast when it is presented at different spatial scales. Our results provide direct evidence for the existence of a higher-level summing circuit tailored to signal information about orientation. The properties of this mechanism differ substantially from edge-detector mechanisms proposed by Marr and others. 相似文献
137.
Over a 21-d experiment, the efficiency of lysine and threonine retention was determined in 80 male Sprague-Dawley rats (65.9 +/- 0.3 g, means +/- SE) fed purified diets containing an amino acid mix limiting in either lysine or threonine. With additional increments of the first limiting amino acid, lysine concentration in total body protein (g/16 g N) increased (P < 0.01) in rats fed lysine-limiting diets but, when fed threonine-limiting diets, lysine concentration in body protein first increased and then decreased (P < 0.01). As increments of the first limiting amino acid were added, the threonine concentration in total body protein increased then decreased when both lysine- (P < 0.01) and threonine- (P < 0.06) limiting diets were fed. Lysine and threonine retention were calculated based on comparative slaughter. Sixteen rats were killed on d 0 to estimate the grams of amino acid in the body. Retention responses were analyzed using a logistic equation in which lysine or threonine intake was used to predict retention. The maximum marginal efficiency (dr/dI, retention/intake) was observed at <40% of maximum retention. For lysine retention, it was 81% when lysine was limiting and 70% when threonine was limiting. For threonine retention, it was 58% when threonine was limiting and 49% when lysine was limiting. The maximum cumulative efficiency (retention adjusted for maintenance relative to cumulative intake) for lysine retention was 62% when lysine was limiting or 58% when threonine was limiting. For threonine retention, it was 51% when threonine was limiting and 35% when lysine was limiting. Thus, amino acid concentration in body protein is not constant, and amino acids are used with higher efficiency when first limiting. 相似文献
138.
139.
The activated coagulation time (ACT) test is technically simple, inexpensive, and commercially available and provides a rapid, accurate assessment of canine whole blood clotting time. The medium ACT for 72 normal dogs ranging in age from 6 monhts to 11 years was 75 seconds, with a range of from less than 60 seconds to 125 seconds and a mean of 77.5 seconds. Significant difference in the ACT due to sex or age of the animals tested was not found. 相似文献
140.