全文获取类型
收费全文 | 2588篇 |
免费 | 10篇 |
专业分类
电工技术 | 21篇 |
化学工业 | 94篇 |
金属工艺 | 13篇 |
机械仪表 | 4篇 |
建筑科学 | 22篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 17篇 |
水利工程 | 5篇 |
无线电 | 25篇 |
一般工业技术 | 49篇 |
冶金工业 | 2289篇 |
原子能技术 | 4篇 |
自动化技术 | 48篇 |
出版年
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 9篇 |
2007年 | 11篇 |
2006年 | 17篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 78篇 |
1998年 | 715篇 |
1997年 | 392篇 |
1996年 | 274篇 |
1995年 | 167篇 |
1994年 | 134篇 |
1993年 | 144篇 |
1992年 | 26篇 |
1991年 | 25篇 |
1990年 | 31篇 |
1989年 | 33篇 |
1988年 | 36篇 |
1987年 | 32篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 19篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 44篇 |
1976年 | 108篇 |
1975年 | 10篇 |
1974年 | 4篇 |
1971年 | 4篇 |
1968年 | 6篇 |
排序方式: 共有2598条查询结果,搜索用时 15 毫秒
21.
An industry-wide survey of plasm fractionation facilities in the United States was conducted during 1973-74. Hepatitis was reported among the workers with varying degrees of plasma contact at all plant sites. For each of fourteen facilities in this investigation, field inspections disclosed: (1) numerous overt instances of employee-product contact: (2) inconsistent methodologic approaches at virtually all stages of the plasma fractionation process; (3) at low level of management and employee awareness regarding the potential bio-hazard identified; and (4) disparate examples of hepatitis surveillance and prophylaxis. Our data suggests that there is a high risk of hepatitis among plasma fractionation workers and, as such, much more attention needs to be focused on the reduction of health hazards within this industry. 相似文献
22.
The effect of prostaglandin E1 (PGE1) on central and peripheral hemodynamics was studied in seven conscious dogs under conditions of normoxia and hypobaric hypoxia to ascertain if hypoxia attenuated the cardiovascular actions of PGE1. Silastic catheters were chronically implanted in the pulmonary artery, left atrium, and aorta. Acute hypoxia was produced in a hypobaric chamber maintained at 446 mmHg pressure (14,000 feet). PGE1 at sea level (normoxia) resulted in significant increases in heart rate, cardiac output, left ventricular stroke work and pulmonary blood volume as well as significant decreases in aortic, pulmonary arterial, and left atrial pressures. During hypobaric hypoxia, PGE1 produced essentially identical effects on all hemodynamic parameters except pulmonary blood volume and pulmonary arterial pressure where marked attenuation of PGE1 action occurred. 相似文献
23.
The right eye of a 9-year-old white boy with Best's vitelliform macular dystrophy had an intact egg-yolk lesion and a retinal pigment epithelial defect superiorly, suggesting an early pseudohypopyon stage. The disruptive phase of the left eye showed subretinal hemorrhages, a "signet ring," and a subretinal neovascular membrane. 相似文献
24.
25.
26.
The mechanism by which beta adrenergic agonist stimulate glycogenolysis in intact skeletal muscle was investigated in mice with the phosphorylase kinase deficiency mutation (I strain). Although extracts of I strain diaphragm muscle had only 3.7% of the phosphorylase kinase activity found in extracts of the control strain (C57BL), incubation of I strain hemidiaphragms in Krebs-Ringer bicarbonate buffer with either isoproterenol or epinephrine resulted in a stimulation of the rate of glycogenolysis. In C57BL diaphragms, the EC50 values for isoproterenol and epinephrine were 2 and 14 nM, respectively. With I strain diaphragms, dl-isoproterenol or l-epinephrine stimulated glycogenolysis as a linear function of the log of the drug concentration with no apparent plateau of response up to concentrations of 30 to 40 mugM. For each 10-fold increase in drug concentration, isoproterenol and epinephrine stimulated glycogenolysis in I strain muscles an additional 0.37 to 0.42 mg/g/hr, a slope in the concentration-response relationship of 0.17 and 0.37, respectively, of that measured in C57BL diaphragms at concentrations around the EC50. The highest glycogenolytic response measured in I strain hemidiaphragms (at 40 mugM isoproterenol) was 80% of the maximal catecholamine-stimulated glycogenolysis in C57BL diaphragms. Both 4 nM and 4 mugM isoproterenol, in a concentration-dependent manner, stimulated phosphorylase b to a conversion in I and C57BL diaphragms and increased cyclic adenosine 3':5'-monophosphate (cyclic AMP) concentrations. The glycogenolytic response to 10.1 nM dl-isoproterenol in both I and C57BL diaphragms was blocked by 34 nM l-propranolol but not by 34 nM d-propranolol. The response to 4 mugM isoproterenol was enhanced by the cyclic nucleotide phosphodiesterase inhibitors papaverine (27 mugM) or dl-4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 20-1724, 3 mugM). From the results of these studies, we conclude: 1) Catecholamines stimulate glycogenolysis in skeletal muscle of I mice, as in C57BL mice, by interacting with the beta adrenergic receptor, thereby increasing tissue cyclic AMP concentrations and stimulating phosphorylase b to a conversion. 2) alternative hypotheses for the mechanism of the catecholamine-stimulated decrease in glycogen concentration in I skeletal muscle-inhibition of glycogen synthesis, hyposia and 5'-AMP stimulation of phosphorylase b activity-have been ruled out. 3) the activity of the mutant phosphorylase kinase, although it is only 3.7% of that in extracts of C57BL muscle, is sufficient to produce phosphorylase b to a conversion and thereby account for the glycogenolytic response of I strain muscle to catecholamines. 相似文献
27.
Heinrich Binder Wolfgang Krainer und Josef Bretschko 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1988,186(3):223-224
Zusammenfassung 1,4-Dichlorbenzol kann als Acaricid gegen die Varroamilbe (Varroa Jakobsoni) eingesetzt werden. Die Analysen bedienen sich der Kopfraum-Technik und erfassen Rückstände in Wachs (Nachweisgrenze 3 mg/kg) und Honig (Nachweisgrenze 0,1 mg/kg).
Treatment of Varroa infection in bees with 1,4-dichlorobenzene: Analysis of residues in wax and honey
Summary 1,4-Dichlorobenzene is used as an acaricidal preparation againstVarroa Jakobsoni. The residues are determined by head space analysis in bees wax (detection limit 3 mg/kg) and in honey (detection limit 0.1 mg/kg).相似文献
28.
Performance of new clean-up column for the determination of ochratoxin A in cereals and foodstuffs by HPLC-FLD 总被引:1,自引:0,他引:1
G. Buttinger E. Fuchs H. Knapp F. Berthiller R. Schuhmacher E. -M. Binder R. Krska 《Food Additives & Contaminants》2004,21(11):1107-1114
The performance of the newly developed Mycosep® 229 Ochra and Multisep® 229 Ochra clean-up columns for ochratoxin A (OTA) determination was evaluated. OTA was subsequently analysed using RP-HPLC with fluorescence detection. Recoveries for frequently contaminated commodities, like cereals, red wine, raisins and green coffee, were estimated. The recoveries obtained for the Mycosep 229 Ochra column were in the range from 87.9 ± 12.5% (n = 6) for wheat to 99.4 ± 2.7% (n = 24) for raisins. For Multisep 229 Ochra, recoveries from 76.5 ± 8.0% (n = 6) for barley to 86.4 ± 1.4% (n = 24) for raisins were achieved. Limits of detection for all matrices investigated (maize, wheat, rice, barley, raisins, green coffee beans, red wine) were in the range 0.4-2.4 μg kg-1. The trueness of the method was tested using a certified reference material. 相似文献
29.
Forschung im Ingenieurwesen - Die mechanischen Verluste von Verbrennungsmotoren hängen maßgeblich von den auftretenden Reibkräften innerhalb der Kolbengruppe ab. Da die Kolbengruppe... 相似文献
30.
TE Dever R Sripriya JR McLachlin J Lu JR Fabian SR Kimball LK Miller 《Canadian Metallurgical Quarterly》1998,95(8):4164-4169
Phosphorylation of eukaryotic translation initiation factor 2alpha (eIF2alpha) is a common cellular mechanism to limit protein synthesis in stress conditions. Baculovirus PK2, which resembles the C-terminal half of a protein kinase domain, was found to inhibit both human and yeast eIF2alpha kinases. Insect cells infected with wild-type, but not pk2-deleted, baculovirus exhibited reduced eIF2alpha phosphorylation and increased translational activity. The negative regulatory effect of human protein kinase RNA-regulated (PKR), an eIF2alpha kinase, on virus production was counteracted by PK2, indicating that baculoviruses have evolved a unique strategy for disrupting a host stress response. PK2 was found in complex with PKR and blocked kinase autophosphorylation in vivo, suggesting a mechanism of kinase inhibition mediated by interaction between truncated and intact kinase domains. 相似文献