全文获取类型
收费全文 | 3038篇 |
免费 | 2篇 |
专业分类
综合类 | 2篇 |
化学工业 | 10篇 |
金属工艺 | 7篇 |
机械仪表 | 7篇 |
建筑科学 | 2篇 |
能源动力 | 9篇 |
轻工业 | 8篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 4篇 |
一般工业技术 | 8篇 |
冶金工业 | 2974篇 |
原子能技术 | 1篇 |
自动化技术 | 3篇 |
出版年
2022年 | 3篇 |
2020年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 10篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 88篇 |
1998年 | 826篇 |
1997年 | 453篇 |
1996年 | 291篇 |
1995年 | 186篇 |
1994年 | 125篇 |
1993年 | 198篇 |
1992年 | 34篇 |
1991年 | 39篇 |
1990年 | 38篇 |
1989年 | 54篇 |
1988年 | 45篇 |
1987年 | 47篇 |
1986年 | 46篇 |
1985年 | 49篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 13篇 |
1981年 | 34篇 |
1980年 | 32篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 106篇 |
1976年 | 246篇 |
1975年 | 14篇 |
1963年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有3040条查询结果,搜索用时 15 毫秒
201.
BACKGROUND: Laparoscopic hysterectomy and lymph node dissection have lately been reported as an alternative to an abdominal open procedure for the treatment of malignant gynaecological conditions. The laparoscopic operative technique has been evaluated and compared as to whether it is a safe, feasible and effective procedure. SUBJECTS: The study includes 78 women with indications for surgery for endometrial cancer stage I. A retrospective comparative study was undertaken at Baby Friendly Hospital, Kladno, in which 11 patients treated laparoscopically were compared with 26 patients treated by the open procedure of lymphadenectomy. We evaluated differences in the peri-and postoperative outcomes. RESULTS: All 11 procedures were successfully completed. The mean operating time was 153 min, and mean blood loss was 130 ml. The median hospital stay was 4.7 days. There were no major complications. CONCLUSIONS: Laparoscopic hysterectomy and lymphadenectomy seem to be the procedures which result in a shorter hospital stay and rapid recovery. This approach could potentially decrease morbidity historically associated with hysterectomy and lymphadenectomy performed abdominally. Only prospective randomised studies will be able to demonstrate the ability of operative laparoscopy to improve contemporary management of endometrial cancer. 相似文献
202.
The polycyclic aromatic hydrocarbon (PAH), chrysene, was linked to the solid support TentaGel S-NH2 via a linker by means of synthesis. The resulting product 4-(chrysene-1-yloxy)-N-(TentaGel S)butanamide (4) was then evaluated for its ability to isolate PAHs from solution by means of π-π-interactions. 相似文献
203.
We have used the combination of pimonidazole labeling of hypoxic cells, bromodeoxyuridine labeling of proliferating cells, and cell sorting based on Hoechst 33342 perfusion to directly study hypoxia and proliferation in human tumor xenografts and transplantable murine tumors in vivo. Hypoxia was largely confined to cells in regions with the least perfusion, although in tumors exhibiting transient blood flow, hypoxic cells were not as highly localized. Similarly, proliferation and hypoxia were mutually exclusive except in areas of a tumor subjected to transient changes in perfusion. By determining the clonogenic potential, pimonidazole labeling intensity, and radiosensitivity of sorted tumor cell subpopulations, we have provided direct evidence that pimonidazole identifies hypoxic tumor cells of therapeutic relevance in vivo. Given that pimonidazole exhibits few diffusion or delivery problems and no apparent cytotoxicity, it appears to be a versatile and useful label for hypoxic cells in solid tumors. 相似文献
204.
205.
JK Tong CA Hassig GR Schnitzler RE Kingston SL Schreiber 《Canadian Metallurgical Quarterly》1998,395(6705):917-921
206.
V Kerekatte BD Keiper C Badorff A Cai KU Knowlton RE Rhoads 《Canadian Metallurgical Quarterly》1999,73(1):709-717
Infection of cells by picornaviruses of the rhinovirus, aphthovirus, and enterovirus groups results in the shutoff of host protein synthesis but allows viral protein synthesis to proceed. Although considerable evidence suggests that this shutoff is mediated by the cleavage of eukaryotic translation initiation factor eIF4G by sequence-specific viral proteases (2A protease in the case of coxsackievirus), several experimental observations are at variance with this view. Thus, the cleavage of other cellular proteins could contribute to the shutoff of host protein synthesis and stimulation of viral protein synthesis. Recent evidence indicates that the highly conserved 70-kDa cytoplasmic poly(A)-binding protein (PABP) participates directly in translation initiation. We have now found that PABP is also proteolytically cleaved during coxsackievirus infection of HeLa cells. The cleavage of PABP correlated better over time with the host translational shutoff and onset of viral protein synthesis than did the cleavage of eIF4G. In vitro experiments with purified rabbit PABP and recombinant human PABP as well as in vivo experiments with Xenopus oocytes and recombinant Xenopus PABP demonstrate that the cleavage is catalyzed by 2A protease directly. N- and C-terminal sequencing indicates that cleavage occurs uniquely in human PABP at 482VANTSTQTM downward arrowGPRPAAAAAA500, separating the four N-terminal RNA recognition motifs (80%) from the C-terminal homodimerization domain (20%). The N-terminal cleavage product of PABP is less efficient than full-length PABP in restoring translation to a PABP-dependent rabbit reticulocyte lysate translation system. These results suggest that the cleavage of PABP may be another mechanism by which picornaviruses alter the rate and spectrum of protein synthesis. 相似文献
207.
208.
EA Ratovitski MR Alam RA Quick A McMillan C Bao C Kozlovsky TA Hand RC Johnson RE Mains BA Eipper CJ Lowenstein 《Canadian Metallurgical Quarterly》1999,274(2):993-999
Nitric oxide (NO) acts as a neurotransmitter. However, excess NO produced from neuronal NO synthase (nNOS) or inducible NOS (iNOS) during inflammation of the central nervous system can be neurotoxic, disrupting neurotransmitter and hormone production and killing neurons. A screen of a hippocampal cDNA library showed that a unique region of the iNOS protein interacts with Kalirin, previously identified as an interactor with a secretory granule peptide biosynthetic enzyme. Kalirin associates with iNOS in vitro and in vivo and inhibits iNOS activity by preventing the formation of iNOS homodimers. Expression of exogenous Kalirin in pituitary cells dramatically reduces iNOS inhibition of ACTH secretion. Thus Kalirin may play a neuroprotective role during inflammation of the central nervous system by inhibiting iNOS activity. 相似文献
209.
A Brockman RE Paul TJ Anderson I Hackford L Phaiphun S Looareesuwan F Nosten KP Day 《Canadian Metallurgical Quarterly》1999,60(1):14-21
PATIENTS AND METHODS: The role of cerebral magnetic resonance imaging (MRI) in the diagnosis of growth hormone (GH) deficiency in children has been studied in 100 children. The diagnosis of GH deficiency was assessed at a mean age of 6.7 +/- 4.1 years: morphological abnormalities of the hypothalamic-pituitary (HP) region have been studied in three different groups: in the first group (70 cases), the neurohypophysis was present and normally located; in the second group (ten cases) it was missing; in the third group (20 cases) the neurohypophysis was ectopic (truncated stalk syndrome with ectopic neurohypophysis, small antehypophysis, thin or non-visualized stalk). RESULTS: In the majority of cases, children presenting with only one morphological abnormality of the HP region (ectopic neurohypophysis or small antehypophysis or non-visualized or thin stalk) had an isolated GH deficiency. When multiple morphological abnormalities were present, anterior pituitary deficiency was multiple in more than half the cases. Cerebral midline anomalies (above all Chiari I malformation and basipharyngeal canal) had been observed in 20% of the children presenting with GH deficiency. In the majority of cases (95%), these anomalies were associated with one or more abnormalities of the HP region. A familial case is reported: morphological anomalies of the HP region were different for both siblings. Genetic factors are evoked. CONCLUSION: The severity of the hormone deficiency is correlated to the ectopic location of the neurohypophysis, the thin appearance or non visibility of the pituitary stalk and the associated midline anomalies. 相似文献
210.