全文获取类型
收费全文 | 1284篇 |
免费 | 0篇 |
专业分类
综合类 | 4篇 |
化学工业 | 5篇 |
金属工艺 | 1篇 |
机械仪表 | 6篇 |
建筑科学 | 2篇 |
能源动力 | 1篇 |
轻工业 | 3篇 |
水利工程 | 1篇 |
无线电 | 4篇 |
一般工业技术 | 16篇 |
冶金工业 | 1228篇 |
自动化技术 | 13篇 |
出版年
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2003年 | 6篇 |
2002年 | 2篇 |
1999年 | 29篇 |
1998年 | 398篇 |
1997年 | 208篇 |
1996年 | 149篇 |
1995年 | 67篇 |
1994年 | 61篇 |
1993年 | 76篇 |
1992年 | 6篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 22篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 3篇 |
1977年 | 36篇 |
1976年 | 77篇 |
1975年 | 2篇 |
1928年 | 1篇 |
1909年 | 1篇 |
1885年 | 4篇 |
排序方式: 共有1284条查询结果,搜索用时 15 毫秒
31.
MR Sowers M Jannausch C Wood SK Pope LL Lachance B Peterson 《Canadian Metallurgical Quarterly》1998,147(10):914-920
Little is known about the epidemiology of renal stones, in spite of the relative frequency of this painful condition. This population-based study examined reported renal stone diagnosis in 1,309 women aged 20-92 years to determine whether renal stones are associated with 1) food or water exposures or 2) lower bone mineral density and an increased likelihood of fractures. Results indicated a renal stone prevalence of 3.4%. The average age at diagnosis was 42 years. Renal stone formation was not associated with community of residence, hypertension, bone mineral density, fractures, high-oxalate food consumption, or ascorbic acid from food supplements. Women with renal stones consumed almost 250 mg/day less dietary calcium (p < 0.01) than did women without stones and had a lower energy intake (p < 0.04). The authors' findings do not support the hypothesis that increased dietary calcium is associated with a greater prevalence of renal stones, nor do they identify renal stones as a risk factor for low bone mineral density. Furthermore, lack of other identifiable environmental correlates and the relatively young age at initial diagnosis suggest that genetic components of renal stone formation need further study. 相似文献
32.
The mitochondrial inner membrane anion channel (IMAC) is a transport pathway which is believed to be involved in mitochondrial volume homeostasis. The protein, however, has not been identified. In this paper, we examine the relationship between IMAC and the adenine nucleotide translocator. Many inhibitors of the adenine nucleotide translocase are shown to block IMAC, including Cibacron blue 3GA, bromcresol green, alizarin red S, agaric acid, palmitoyl-CoA, and the fluorescein derivatives erythrosin B, erythrosin isothiocyanate, rose bengal, and eosin Y. The following evidence suggests that Cibacron blue, agaric acid, and palmitoyl-CoA inhibit by binding to a common site. 1) They all only partially block the transport of small anions such as Cl-, NO3-, and HCO3-, but completely block the transport of larger anions such as malonate. 2) They decrease the IC50 values of each other in a manner consistent with competitive binding. 3) N-Ethylmaleimide decreases their IC50 values by a similar extent. 4) Inhibition by all shows no dependence on matrix pH and only a small dependence on medium pH. It is suggested that these agents may selectively bind to an open state of IMAC and inhibit by decreasing its conductance. The physiological nucleotides CoA, NAD+, NADH, NADP+, NADH, and ATP do not inhibit; in fact, IMAC is shown to transport ATP. Despite these similarities between IMAC and the adenine nucleotide translocase, IMAC appears to be a separate entity, since some of the IC50 values differ by up to 8-fold, and carboxyatracyloside, the most selective inhibitor of the adenine nucleotide translocase, has no effect on IMAC. In addition, IMAC is also able to transport AMP, while the adenine nucleotide translocase does not. 相似文献
33.
JP Gagliardi RE Nettles DE McCarty LL Sanders GR Corey DJ Sexton 《Canadian Metallurgical Quarterly》1998,26(5):1165-1168
The effect of age on the presentation and outcome of infective endocarditis (IE) is unclear. Many of the available data are based on analyses of mixed populations of patients including intravenous drug users or those with prosthetic valve endocarditis or native valve IE. We used the Duke criteria to compare the characteristics of 44 episodes of definite native valve IE in elderly patients (> 64 years old) with the characteristics of 64 similarly defined episodes of native valve IE in younger, nonintravenous-drug-using adult patients (> 29 years and < 60 years old). Our data suggest that the clinical presentation, characteristics, and outcome of native valve IE are similar for elderly patients and younger adult patients, although elderly patients were hospitalized an average of 12 days longer. Although we found that the occurrence of renal failure and cerebral embolism during an episode of IE was associated with higher rates of death (odds ratios, 4.8 and 4.0, respectively), age was not a significant contributor to mortality. 相似文献
34.
MJ Telford JW Martin BJ Rock LL Turik JE Hairfield 《Canadian Metallurgical Quarterly》1994,19(3):25-9, 33
Small local chapter groups can present quality cost effective regional seminars. Key components are dedication of members, teamwork, and a sense of direction. The following guidelines and information can provide a framework for planning and coordinating a seminar. 相似文献
35.
36.
LL Bachrach 《Canadian Metallurgical Quarterly》1996,47(10):1071-1078
OBJECTIVES: This analytical review is intended to update the author's earlier writings on the position of the state mental hospital within the spectrum of services for long-term mental patients and to provide perspective for the next generation of service planners. METHODS: Findings and commentary are organized around four major questions. First, what is the prevailing view of state mental hospitals today, and how does it compare with the view that existed in the first half of this century? Second, what individuals tend to be served in state mental hospitals today? Third, what has been the fate of mentally ill persons who are no longer served in state mental hospitals? Fourth, what is an appropriate role for the state mental hospital in today's uncertain and rapidly changing systems of care? Source material consists of periodical articles suggested in MEDLINE searches, plus newspaper reports, recent books on mental health service systems, and a variety of writings found in the "fugitive" literature generally not indexed in traditional archives. RESULTS AND CONCLUSIONS: Individual state mental hospitals vary in the composition of their resident populations, the content of their services, and the overall quality of their care. Although they have been superseded by community-based service structures in some places, they continue in general, as the result of their multifunctionality, to occupy a critical place in systems of care. Renewed efforts to integrate them as full partners within those systems must be undertaken. 相似文献
37.
With the ever-increasing use of pharmaceuticals and the relatively high risk of developing drug allergies, particularly for patients in hospitals and for ambulatory patients with a history of drug allergy, the need to develop in vitro assays for drug allergy is great. In the early 1970's a mast cell technique was developed for diagnosis of drug allergies. A PRIST inhibition assay has also recently been developed to detect IgE antibodies to drug allergens. This test has also been referred to as the Total IgE Inhibition Test by Specific Drug Allergen, and is a variant of the in vitro RAST Test. In vitro mast cell and IgE inhibition tests are applied for identification of drug and chemical allergens and for their cautious clinical trial to prevent future drug and chemical reactions. Over the last eight years, over 1,300 patients were examined utilizing the mast cell technique. Over 100 drugs were tested, with penicillin, barbiturates, "caine" derivatives and sulfonamides most frequently employed. Of 270 patients with well-defined drug reactions, 190 (70 per cent) gave a positive response to the mast cell test. Eighty-five per cent of sera tested with Type I reactions gave a mast cell response. Of these, a group of 30 patients was studied with PRIST inhibition as well. Procedures for comparative testing of necessary drugs and/or chemicals in cases of high anaphylaxis risk of reaction in the clinical setting, hospital or office are included in the study as well as individual case reports. Mast cell assay coupled with IgE inhibition has been successfully used to diagnose drug and chemical allergic reactions. The incidence of positivity is high when the offending drug causes a Type I allergic reaction. The cases reported indicate that both the Mast Cell and the PRIST inhibition assays are useful for diagnosing and setting the clinical treatment and clinical course of the patient. The mast cell assay would be potentially employed for patient use in hospitals where the incidence of drug allergy is highest and for occupational health in the chemical industry. The greatest potential would be in outpatient care applied to patients with multiple drug allergies in the selection of safe drugs (test negative by both methods, and other clinical studies) for future drug usage. 相似文献
38.
RH Margolis PL Schachern LL Hunter C Sutherland 《Canadian Metallurgical Quarterly》1995,34(5):232-247
Multifrequency tympanometry (MFT), using probe frequencies ranging from 226-2,000 Hz, was performed on normal chinchillas to obtain normative data against which to compare results from animals with middle ear pathology. A series of validating experiments was conducted to determine the effects of anatomical alterations of the middle ear on MFT. These included artificially extending the ear canal, opening the bulla, injecting saline into the middle ear, and disrupting the ossicular chain. The results indicate that MFT characteristics of chinchilla ears are qualitatively similar to those observed in normal humans and patients with middle ear disease, and MFT provides information that is not available from the 226-Hz tympanogram. 相似文献
39.
JJ Fins FG Miller CA Acres MD Bacchetta LL Huzzard BD Rapkin 《Canadian Metallurgical Quarterly》1999,17(1):6-15
The contributions of the various ulnar-innervated muscles of the hand to the hypothenar compound muscle action potential (CMAP) were estimated by directly stimulating individual muscles and by analyzing CMAP shape changes resulting from manipulations that changed individual muscle lengths. The results show that the first peak of the negative phase of the hypothenar CMAP comes from the hypothenar muscles, but that the second peak is due to a large volume-conducted potential from the interosseous muscles. The interosseous contribution affects both the amplitude and the area of the CMAP, and makes these parameters sensitive to changes in the configuration of the fingers and the temperature gradient in the hand. To reduce the interosseous contribution, a "balanced reference" consisting of two reference electrodes, one over each tendon, is proposed. 相似文献
40.
AR Jude DV Greathouse RE Koeppe LL Providence OS Andersen 《Canadian Metallurgical Quarterly》1999,38(3):1030-1039
In the linear gramicidins, the four aromatic residues at positions 9, 11, 13, and 15 are well-known to be important for the structure and function of membrane-spanning gramicidin channels. To investigate whether the "spacer" residues between the tryptophans in gramicidin A (gA) are important for channel structure and function, D-Leu-10, -12. and -14 of gA were replaced by Ala, Val, or Ile. (For practical reasons, the Ile substitutions were introduced into the enantiomeric gramicidin A-, gA-.) Circular dichroism spectra of [D-Ala10,12,14]gA, [D-Val10,12,14]gA, or [Ile10,12,14]gA- incorporated into sodium dodecyl sulfate micelles or 1, 2-dimyristoyl-sn-glycero-3-phosphocholine vesicles differ from the spectrum of the native [D-Leu10,12,14]gA. All the analogue spectra display reduced ellipticity at both 218 and 235 nm, indicating the presence of double-stranded conformers with the Ala analogue spectra showing the largest departure from the native gA spectra. Size-exclusion chromatograms of the Val and Ile analogues show both monomer and dimer peaks, accompanied by peak broadening; the chromatograms for the Ala analogue show broad, overlapping peaks and suggest the presence of higher oligomers and/or (rapidly) interconverting conformations. All three analogues form membrane-spanning channels, with the channel-forming potency of the Ala analogue being much less than that of gA or the other analogues. In 1.0 M CsCl, the conductance of each analogue channel is approximately 25% less than that of [D-Leu10,12,14]gA channels. The lifetimes of the analogue channels also are less than of [D-Leu10,12, 14]gA channels, with the largest (8-fold) reduction being for [D-Ala10,12,14]gA channels. Hybrid channel experiments show that the beta6.3-helical backbone folding pattern is retained in the channel-forming subunits and that the substitutions primarily influence ion entry. Both the bulk and the stereochemistry of the aliphatic residues between the tryptophans of gA are important for channel structure and function. 相似文献