全文获取类型
收费全文 | 3988篇 |
免费 | 9篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 29篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
建筑科学 | 5篇 |
能源动力 | 15篇 |
轻工业 | 35篇 |
石油天然气 | 2篇 |
无线电 | 2篇 |
一般工业技术 | 7篇 |
冶金工业 | 3876篇 |
原子能技术 | 7篇 |
自动化技术 | 13篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 2篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2000年 | 4篇 |
1999年 | 109篇 |
1998年 | 1158篇 |
1997年 | 699篇 |
1996年 | 450篇 |
1995年 | 222篇 |
1994年 | 223篇 |
1993年 | 213篇 |
1992年 | 20篇 |
1991年 | 48篇 |
1990年 | 36篇 |
1989年 | 45篇 |
1988年 | 33篇 |
1987年 | 42篇 |
1986年 | 53篇 |
1985年 | 34篇 |
1984年 | 1篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 25篇 |
1980年 | 51篇 |
1979年 | 3篇 |
1978年 | 9篇 |
1977年 | 110篇 |
1976年 | 263篇 |
1975年 | 7篇 |
1973年 | 1篇 |
1964年 | 1篇 |
1955年 | 5篇 |
1954年 | 2篇 |
排序方式: 共有3997条查询结果,搜索用时 0 毫秒
991.
JF Magrina 《Canadian Metallurgical Quarterly》1996,(21):53-59
Radical hysterectomy and pelvic lymphadenectomy are indicated for the treatment of cervical carcinoma that is localized clinically to the cervix and upper vagina. Intraoperative complications have been reported in 1.1%-7.4% of patients. Long-term complications include bladder dysfunction (2% at 3 years), urinary fistula (vesical, 0.8%; ureteral, 1.2%), stress urinary incontinence (29%), ureteral stricture (1%), rectal dysfunction (80%), severe constipation (5.3%), lymphocysts (20% by ultrasonography; 2% clinically), and lymphedema (10%). The operative mortality is 0.7%. The 5-year survival rate for patients with stage IB disease is 85.7% and for stage IIA is 69.6%. The recurrence rate is 27.2%. Recurrences are distributed equally between the pelvis and extrapelvic sites. Radical hysterectomy is the treatment of choice for pregnant patients with early cervical cancer. It affords termination or delivery of the pregnancy at the same time that the treatment is provided. For patients with stage I disease treated with radical hysterectomy, the survival rate is 92.1%. 相似文献
992.
993.
JF Dorgan JT Judd C Longcope C Brown A Schatzkin BA Clevidence WS Campbell PP Nair C Franz L Kahle PR Taylor 《Canadian Metallurgical Quarterly》1996,64(6):850-855
We conducted a controlled feeding study to evaluate the effects of fat and fiber consumption on plasma and urine sex hormones in men. The study had a crossover design and included 43 healthy men aged 19-56 y. Men were initially randomly assigned to either a low-fat, high-fiber or high-fat, low-fiber diet for 10 wk and after a 2-wk washout period crossed over to the other diet. The energy content of diets was varied to maintain constant body weight but averaged approximately 13.3 MJ (3170 kcal)/d on both diets. The low-fat diet provided 18.8% of energy from fat with a ratio of polyunsaturated to saturated fat (P:S) of 1.3, whereas the high-fat diet provided 41.0% of energy from fat with a P:S of 0.6. Total dietary fiber consumption from the low- and high-fat diets averaged 4.6 and 2.0 g.MJ-1.d-1, respectively. Mean plasma concentrations of total and sex-hormone-binding-globulin (SHBG)-bound testosterone were 13% and 15% higher, respectively, on the high-fat, low-fiber diet and the difference from the low-fat, high-fiber diet was significant for the SHBG-bound fraction (P = 0.04). Men's daily urinary excretion of testosterone also was 13% higher with the high-fat, low-fiber diet than with the low-fat, high-fiber diet (P = 0.01). Conversely, their urinary excretion of estradiol and estrone and their 2-hydroxy metabolites were 12-28% lower with the high-fat, low-fiber diet (P < or = 0.01). Results of this study suggest that diet may alter endogenous sex hormone metabolism in men. 相似文献
994.
Y Horsmans A Laka BE van Beers C Descamps JF Gigot AP Geubel 《Canadian Metallurgical Quarterly》1997,42(7):1406-1408
Hepatobiliary cystadenoma and cystadenocarcinoma are rare tumors of the liver. The differential diagnosis of cystadenoma includes other cystic neoplasms, nonneoplastic cysts, and even on some occasions parasitic liver involvement. It has been suggested that elevated serum level of the tumor marker CA 19-9 may be of value in distinguishing between cystadenoma with ovarian stroma and hydatid disease. We report the unique case of a male patient with a hepatobiliary cystadenocarcinoma without ovarian stroma of prolonged evolution characterized by a normal CA 19-9 serum level, low cyst fluid CA 19-9, and a very weak CA 19-9 expression on cyst epithelium. 相似文献
995.
Variations of the male partner fertility according to his age are difficult to study, because of bias represented by some decrease of both sexual activity and fecundity of the female partner beyond 35 years old. The few studies which are available show that sperm concentration as percentage of normal forms, are stable with age. The percentage of motility is the only parameter which decreases systematically with age according to all studies. Nevertheless, sperm fertilizing capacity does not seem to be decreased. FIVNAT data allow to analyse almost 30,000 IVF cycles for tubal sterility; they confirm the absence of an important alteration of semen characteristics with age. Despite a significant decrease--even moderate--of the mean fertilization rates, the pregnancy rates remain roughly constant for a given range of maternal age. 相似文献
996.
JF Hirsch 《Canadian Metallurgical Quarterly》1997,13(8-9):465-470
Up to 1960, children in need of neurosurgical treatment in France were treated either in neurosurgical departments where anesthetists, nurses and neurosurgeons had no specialized training in pediatrics or in departments of pediatric surgery in which the specific aspect of neurosurgery was ignored. Clearly a mutation was needed before any progress could be made: the development of pediatric neurosurgery services. This essay tells the story of the creation of the first pediatric neurosurgery service in France, of the difficulties encountered and of the strategies applied to overcome them. It also recalls the discussions about what size such a service should be and whether it should be located in a general hospital or in a pediatric hospital. During the second half of the twentieth century, progress in neurosurgery, and more specifically in pediatric neurosurgery, has been tremendous. The contribution of the pediatric neurosurgery service at Les Enfants Malades in Paris is briefly summarized. 相似文献
997.
In myasthenia gravis (MG) the muscle acetylcholine receptor (AChR) is the target of an autoimmune response. The anti-AChR response may originate in the thymus, which is abnormal in most MG patients and contains anti-AChR T and B cells. Microbial superantigens (sAg) may trigger autoimmune responses and in this study we sought clues as to whether sAg play a role in the pathogenesis of MG. We investigated the frequency of use of the different TCR Vbeta families by the thymus and blood T cells in MG patients and in control subjects, using a multi-primer PCR assay. Identical TCR-Vbeta usage was found in the thymi of MG patients and controls, except Vbeta2, which showed a small increase in MG patients' thymi. Blood T cells of MG patients used Vbeta4, Vbeta6, Vbeta15, Vbeta16 and Vbeta24 significantly more than those of the controls. Vbeta4 and Vbeta6 are the gene families most frequently used by anti-AChR CD4(+) cells in MG patients. Blood T cells from MG patients used Vbeta12, Vbeta14, Vbeta17 and Vbeta18 significantly less than controls. MG patients used Vbeta4 and Vbeta6 significantly more in the blood than in the thymus, while the opposite occurred for Vbeta7, Vbeta12 and Vbeta14. Controls used Vbeta17 more and Vbeta24 less in the blood than in the thymus. The preferential expansion of Vbeta4 and Vbeta6 in MG patients might reflect the immunodominance of certain AChR epitopes, or the action of a sAg outside the thymus. The minimal differences in the TCR-Vbeta usage in the blood and thymus of control subjects might be due to expansion of T cell clones specific for common antigens. Identical Vbeta usage in the thymi of MG patients and controls does not support an important role of the thymus as the location of anti-AChR sensitization when MG is clinically evident. The differences observed in the Vbeta usage in blood and thymi of MG patients are likely to be due to preferential Vbeta usage by the anti-AChR T cells in the blood. 相似文献
998.
999.
The cyanogen bromide (CNBr)/formic acid cleavage reactions of wild-type and trifluoromethionine (TFM)-containing recombinant lambda lysozyme were studied utilizing ESI and MALDI mass spectrometry. Detailed analysis of the mass spectra of reverse-phase HPLC-purified cleavage fragments produced from treatment of the wild-type and labeled proteins with CNBr indicated cleavage solely of methionyl peptide bonds with no observation of cleavage at TFM. N-Acetyl-TFM was also found to be resistant to reaction with CNBr, in contrast to N-acetyl-methionine. The analysis also indicated differential reactivity among the three methionine positions in the wild-type enzyme. Additionally, formylation of intact enzyme as well as peptide fragments were observed and characterized and indicated that serine, threonine, as well as C-terminal homoserine side chains are partially formylated under standard cleavage protocols. 相似文献
1000.
NK Khoo JF Bechberger T Shepherd SL Bond KR McCrae GS Hamilton PK Lala 《Canadian Metallurgical Quarterly》1998,77(3):429-439