全文获取类型
收费全文 | 1834篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 32篇 |
金属工艺 | 3篇 |
机械仪表 | 21篇 |
建筑科学 | 5篇 |
能源动力 | 12篇 |
轻工业 | 18篇 |
水利工程 | 1篇 |
石油天然气 | 6篇 |
无线电 | 28篇 |
一般工业技术 | 22篇 |
冶金工业 | 1656篇 |
自动化技术 | 35篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 26篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 1篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 4篇 |
1999年 | 44篇 |
1998年 | 489篇 |
1997年 | 289篇 |
1996年 | 202篇 |
1995年 | 95篇 |
1994年 | 95篇 |
1993年 | 112篇 |
1992年 | 15篇 |
1991年 | 29篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 22篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 14篇 |
1983年 | 2篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 46篇 |
1976年 | 100篇 |
1975年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有1840条查询结果,搜索用时 11 毫秒
71.
The paper presents the results of examination of 110 alcoholic patients who have committed criminal actions and were recognized as irresponsible at forensic examination. It was established that wide spectrum of mental disorders were present in such cases--from superacute psychotic states (15 patients) and acute disorders (49) to chronic psychoses (33) and encephalopathy (13). According to clinical manifestations mental disorders correspond in such cases to reactions of exogenic type. In contrast to general medical departments where patients with alcoholic delirium prevail, the studied sample of patients had primarily psychoses with hallucinative-delirious and delirious disorders. Disorders of personality manifested as typical alcoholic, asthenoneurotic, psychopathic-like, residual-psychotic, psychoorganic changes and partial dementia (19 cases). 相似文献
72.
BACKGROUND: We determined whether activation of the nitric oxide/cyclic guanosine monophosphate pathway by sodium nitroprusside (SNP) protects hearts subjected to cardioplegic arrest and prolonged hypothermic storage. METHODS: Isolated rat hearts arrested with St. Thomas' II cardioplegia and stored at 3 degrees +/- 1 degree C for 8 hours were reperfused at 37 degrees C in Langendorff (10 minutes) and working (60 minutes) modes. RESULTS: During reperfusion, left ventricular work was depressed in stored hearts relative to fresh hearts. When present during arrest, storage, and both reperfusion phases, SNP (200 mumol/L) improved work to values close to those in fresh hearts. When added only during the 10-minute period of Langendorff reperfusion, SNP also improved the subsequent recovery of work. This effect was antagonized by the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Poststorage coronary perfusion was not increased by SNP. CONCLUSIONS: The ability of SNP to enhance recovery independent of changes in coronary perfusion and in an ODQ-sensitive manner suggests that SNP-induced protection is due to activation of the myocardial nitric oxide/cyclic guanisine monophosphate pathway. These results suggest that supplementing cardioplegic solutions with SNP, administering SNP during early reperfusion, or both may offer additional means to improve donor heart preservation. 相似文献
73.
Compound I of Proteus mirabilis and bovine liver catalases (PMC and BLC, respectively) were studied combining EPR spectroscopy and the rapid-mix freeze-quench techniques. Both enzymes, when treated with peroxyacetic acid, form a catalytic intermediate which consists of an oxoferryl porphyrin pi-cation radical. In PMC this intermediate is semistable, and an unexpected reversible equilibrium under pH influence takes place between two forms of compound I with different coupling between the oxoferryl and the porphyrin pi-cation radical. At acid pH, one form has a ferromagnetic character as in Micrococcus luteus compound I. At neutral pH, another form with a much smaller coupling, reminiscent of the horse radish peroxidase compound I, is detected. The approximate midpoint, estimated for these changes in the range 5.3 < pH < 6.0, approaches the pKa value of an histidyl residue. The residues possibly involved in the transformation are discussed in terms of the known structure of PMC compound I. The EPR spectrum of BLC compound I (pH 5.6), obtained in the millisecond time scale (40 ms), also showed a mixture of two forms which, most probably, correspond to two different magnetic exchange interactions, as in the case of PMC. Taken together, the low-temperature electronic absorption and the EPR spectra of BLC compound I formed in the 0.04-15 s range show that the porphyrin pi-cation radical disappears and, instead, a tyrosyl radical is formed. ENDOR experiments confirm our previously estimated hyperfine couplings to the C2,6 and C3,5 ring protons and the beta-methylene protons of the purported tyrosyl radical. Candidates for such a tyrosyl radical are discussed in connection with the possible electron transfer pathways between the heme active site and the NADPH cofactor. 相似文献
74.
Hypocomplementemic urticarial vasculitis (HUV) is often misdiagnosed. The response to drug therapy may be unsatisfactory, and immunosuppressive therapy may be associated with significant side effects. A 35-year-old patient whose condition was resistant to cyclophosphamide, corticosteroids, pentoxyphylline, cyproheptadine, sulindac, and colchicine was maintained in remission with dapsone, which may be the drug of choice for HUV. Emphysema has been reported to complicate HUV, but this is the first account of vasculitis-related emphysema with no confounding history of tobacco smoke exposure. The relationship of proteolytic injury to the pulmonary and other manifestations is considered, as is the possible role for dapsone in reducing it. 相似文献
75.
35 patients with complex regional pain syndrome (CRPS) were treated by hyperbaric oxygenation (HBO) and caffetin preparation. A significant decrease of pain was observed in all the patients after the treatment course. Intensity of pain was diminished according to visual analogous scale. Meanwhile considerable regression of autonomic disorders and weakening of anxious and depressive manifestations was noted too. The tendency to normalization of evoked skin potentials was also found. Some elevation of the threshold of nociceptive reflex was conditioned by displacement toward general increase of antinociception after the treatment. Effect of HBO therapy persisted during 6 months in 87% of the patients. Efficiency of caffetin was restricted by the time of its administration. The conclusion was made about possibility of successful treatment of CRPS patients by both methods. 相似文献
76.
The intricate connectivity and interactions between neurons in the vertebrate retina have made their individual roles in signal processing very difficult to elucidate. We have used a recently developed mathematical tool, fast orthogonal search (FOS), to probe the catfish outer (distal) and inner (proximal) retina, and study the signal processing within. Through FOS, a given waveform can be decomposed into a parsimonious sinusoidal series containing the most significant constituent frequencies. In particular, we examined the light-evoked first-order Wiener kernels of horizontal cells and on-bipolar cells, and on-off, off- and on-amacrine and ganglion cells. Here we report a hierarchy (correlation coefficient up to 0.86) in preferred frequency and complexity of response corresponding to the retina's structural hierarchy. In addition, clear differences between on-, on-off and off-cell functional characteristics were detected. For example, the kernel waveform for the on-amacrine cell was found to be more complex and to have a higher preferred frequency than that for the off-amacrine cell. Indeed FOS analysis revealed that both off- (sustained) amacrine and off-ganglion cells exhibit significantly less complexity in their waveforms for signal processing of light input than do the corresponding on- and on-off cells. This shows a clear breakdown in symmetry between on- and off-pathways, and suggests that connections to off-cells may provide fewer or a smaller variety of inputs than those to on- and on-off cells. Many of our new findings can be appreciated by assuming an underlying cascade structure for the retinal information processing. The FOS findings in particular support the following previously advanced hypothesis: the transition in nonlinear processing from on-off amacrine to on- off-amacrine cells is due to high-pass linear filtering. Furthermore, our results indicate that the high-pass filtering is more sharply differentiating for the on-amacrine than for the off-amacrine cell. 相似文献
77.
78.
79.
PURPOSE: The 2 types of urethral injury that can occur during circumcision are urethrocutaneous fistula and urethral distortion secondary to partial glans amputation. We report the surgical repair of these rare injuries. MATERIALS AND METHODS: In 8 patients urethrocutaneous fistulas located on the distal penile shaft or at the coronal margin were managed by splitting the glans and using a Mathieu style skin flap in 4 or vascularized penile skin flap in 4 to bridge the urethral defect. Three patients underwent repair of a hypospadiac deviated urethra secondary to partial glans amputation by 1 cm. of urethral mobilization and repositioning the meatus into a terminal position within the remaining glans tissue. RESULTS: The 8 patients with urethrocutaneous fistulas voided via a terminal meatus without fistula recurrence at a mean followup of 3.2 years (range 1 to 6). The 3 patients with partial glans amputation and urethral deviation repaired by short urethral advancement had functionally acceptable results, defined as a normal urinary stream, although 1 required meatal dilation postoperatively. CONCLUSIONS: The 2 types of urethral injuries that can occur during circumcision are a subcoronal urethrocutaneous fistula and scarred abnormal urethra from partial glans amputation. The urethrocutaneous fistula can be successfully repaired by splitting the glans and forming a neourethra from a vascularized pedicle flap of penile skin. The abnormal urethra after partial glans amputation is more difficult to repair but repositioning the urethra in a more cosmetic location has restored function. 相似文献
80.
GA Macones HM Sehdev S Parry MA Morgan JA Berlin 《Canadian Metallurgical Quarterly》1997,177(5):1097-1100
We compared various diagnostic tests for their abilities to detect Mycobacterium ulcerans infection in specimens from patients with clinically active disease. Specimens from 10 patients from the area of Zangnanado (Department of Zou, Benin) with advanced, ulcerated active M. ulcerans infections were studied by direct smear, histopathology, culture, PCR, and oligonucleotide-specific capture plate hybridization (OSCPH). A total of 27 specimens, including 12 swabs of exudate collected before debridement and 15 fragments of tissue obtained during debridement, were submitted to bacteriologic and histopathologic analysis. The histopathologic evaluation of tissues from all six patients so tested revealed changes typical of those caused by M. ulcerans infection. Five specimens were contaminated, and M. ulcerans was cultivated on L?wenstein-Jensen medium from 12 of the remaining 22 (54.5%) specimens. Detection of mycobacteria was performed by PCR, and M. ulcerans was detected by OSCPH with a new probe (5'-CACGGGATTCATGTCCTGT-3') reacting with M. ulcerans and Mycobacterium marinum. In 10 of 22 (45.5%) specimens, M. ulcerans was identified by PCR-OSCPH. There was no statistically significant difference between the detection of M. ulcerans by culture and by PCR-OSCPH (P > 0.05). This is the first demonstration of an amplification system (PCR-OSCPH) with a sensitivity similar to that of culture for the direct and rapid recognition of M. ulcerans in clinical specimens. This system is capable of identifying M. ulcerans, even in paucibacillary lesions. Our findings suggest that PCR-OSCPH should be used in the quest for the elusive environmental reservoir(s) of M. ulcerans. 相似文献