全文获取类型
收费全文 | 1657篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 6篇 |
建筑科学 | 1篇 |
轻工业 | 8篇 |
无线电 | 1篇 |
一般工业技术 | 2篇 |
冶金工业 | 1638篇 |
原子能技术 | 1篇 |
自动化技术 | 1篇 |
出版年
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2010年 | 3篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
1999年 | 47篇 |
1998年 | 423篇 |
1997年 | 253篇 |
1996年 | 198篇 |
1995年 | 83篇 |
1994年 | 93篇 |
1993年 | 116篇 |
1992年 | 15篇 |
1991年 | 26篇 |
1990年 | 28篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 30篇 |
1986年 | 40篇 |
1985年 | 24篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 21篇 |
1978年 | 5篇 |
1977年 | 53篇 |
1976年 | 114篇 |
1975年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有1658条查询结果,搜索用时 15 毫秒
81.
We investigated the clinical and angiographic risk profile of slow flow during rotational atherectomy. Lesion length, angina at rest, and use of beta blockers correlated independently with slow flow in the univariate as well as in the multivariate analysis. 相似文献
82.
83.
RF Tsuji GP Geba Y Wang K Kawamoto LA Matis PW Askenase 《Canadian Metallurgical Quarterly》1997,186(7):1015-1026
Complement (C) is an important component of innate immunity, and was also shown recently to participate in induction of acquired B cell humoral immunity. In this study, we present evidence that C also participates in acquired T cell immunity. We found that C was involved in early events of the efferent elicitation phase of contact sensitivity (CS), and delayed-type hypersensitivity (DTH). Thus, CS and DTH were inhibited by administration of a C-blocker, soluble recombinant C receptor-1 (sCR1), when given 30 min before, but not 3 h after local antigen challenge. Among C components, local C5 were thought crucial to elicitation of CS, since local administration of anti-C5 monoclonal antibodies or locally injected C-depleting cobra venom factor also inhibited CS and DTH. These findings were consistent with our previous finding of the importance of C5 for CS elicitation, using congenitally C5-deficient mice. To dissect the mechanism of C dependence in CS, we demonstrated that locally increased early macrophage chemotactic activity (probably C5a) in evolving CS skin extracts, as well as late elaboration of IFN-gamma, were both inhibited by anti-C treatment. In addition, histological analysis showed that leukocyte recruitment into CS ear sites was similarly C-dependent. Furthermore, an initiating role of B cell-derived C-fixing immunoglobulin was suggested by demonstration of impaired CS responses in B cell-deficient mice. In summary, these results suggest that C was activated locally, perhaps via a B cell product, in an important early component of the stepwise events necessary to elicit CS, leading to local production of C5-dependent macrophage chemotactic activity and later IFN-gamma, and subsequently leading to cell infiltration, for development of T cell-dependent CS. 相似文献
84.
Hydroxyurea (HU) treatment of early first instar larvae in Drosophila was previously shown to ablate a single dividing lateral neuroblast (LNb) in the brain. Early larval HU application to P[GAL4] strains that label specific neuron types enabled us to identify the origins of the two major classes of interneurons in the olfactory system. HU treatment resulted in the loss of antennal lobe local interneurons and of a subset of relay interneurons (RI), elements usually projecting to the calyx and the lateral protocerebrum (LPR). Other RI were resistant to HU and still projected to the LPR. However, they formed no collaterals in the calyx region (which was also ablated), suggesting that their survival does not depend on targets in the calyx. Hence, the ablated interneurons were derived from the LNb, whereas the HU-resistant elements originated from neuroblasts which begin to divide later in larval life. Developmental GAL4 expression patterns suggested that differentiated RI are present at the larval stage already and may be retained through metamorphosis. 相似文献
85.
86.
87.
M Rios RF Khabbaz JE Kaplan WW Hall D Kessler C Bianco 《Canadian Metallurgical Quarterly》1994,170(1):206-210
Blood donors have been screened for antibodies to human T cell lymphotropic virus (HTLV) type I since December 1988. Screening for HTLV-II has been simultaneously done because of cross-reactivity between antibodies to the two viruses. Currently, < 1 in 10,000 US blood donors is positive for HTLV-I or -II. Lookback studies led to the identification of 6 HTLV-II-infected patients. Three received transfusions before introduction of HTLV-I screening tests, while the other 3 received blood components that tested negative for HTLV-I. The HTLV-II subtypes of each of 4 donor/recipient pairs, as determined by DNA amplification using polymerase chain reaction, were identical, supporting the view that transfusions were the source of infection. In conclusion, currently licensed blood donor screening tests for HTLV-I lack sensitivity for HTLV-II, and transfusion of blood from HTLV-II-infected donors that test negative on HTLV-I screening tests may result in infection. 相似文献
88.
RF Davies 《Canadian Metallurgical Quarterly》1998,21(3):154-156
Implantable left-ventricular assist devices have been remarkably free of mechanical failures. We describe an uncommon Novacor N100 PCq LVAS malfunction caused by an internal short circuit of the device due to urine aspiration via the vent line. Device replacement was managed via a subcostal approach without sternotomy. Patient recovery was uneventful and successful transplantation was performed one month after the device exchange. 相似文献
89.
Arterial embolization was performed in ten skeletal metastases occurring in nine patients: eight patients presented with renal cell carcinoma and one with bronchogenic carcinoma. Five metastatic lesions were located in the spine, one in the pelvis, three in the proximal humerus and one in the proximal femur. Selective arterial embolization was performed preoperatively in seven cases and as a palliative treatment in three cases. The embolic material used was polyvinyl alcohol particles, gelatin sponge and coils or a combination of these. Arterial embolization was technically successful in all patients achieving subtotal (> 90%) tumour devascularization in five metastases and a 75% devascularization in the remaining five lesions. In operative patients, median intra-operative volume of blood transfusion was 510 mL. Palliative embolization was followed by major pain relief in two cases and moderate relief in one case lasting from 7 to 26 months. Arterial embolization is an effective and safe adjunctive treatment of hypervascular bone metastases. 相似文献
90.
JW Kleinfelder HH Topoll HR Preus RF Müller DE Lange W B?cker 《Canadian Metallurgical Quarterly》1996,23(11):1032-1038
The following communication is a case history of an 11 year-old female patient suffering from Papillon-Lefèvre syndrome. Since a massive occurrence of A. actinomycetemcomitans had been found in the subgingival microflora of the periodontal pockets, the patient was treated with repeated subgingival scaling, with an adjunct Amoxicillin and Metronidazol treatment. A bacteriological examination of the girl's family proved that several brothers and sisters as well as one parent also carried. A. actinomycetemcomitans, showing 3 different strains of this bacterium within the family. An immunohistological examination of the gingival tissue showed a massive inflammatory infiltrate which was dominated by plasma cells. The histological investigation of the first molars did not show morphological abnormalities of the root cementum. Posttreatment clinical and radiographical improvement of the periodontal conditions is reported despite the recurrent finding of A. actinomycetemcomitans. 相似文献