全文获取类型
收费全文 | 6494篇 |
免费 | 3篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 36篇 |
金属工艺 | 4篇 |
机械仪表 | 1篇 |
建筑科学 | 19篇 |
能源动力 | 2篇 |
轻工业 | 28篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 13篇 |
一般工业技术 | 36篇 |
冶金工业 | 6314篇 |
原子能技术 | 1篇 |
自动化技术 | 33篇 |
出版年
2023年 | 3篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 2篇 |
2015年 | 2篇 |
2013年 | 11篇 |
2012年 | 7篇 |
2011年 | 3篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 14篇 |
2003年 | 23篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 13篇 |
1999年 | 215篇 |
1998年 | 2007篇 |
1997年 | 1094篇 |
1996年 | 788篇 |
1995年 | 404篇 |
1994年 | 339篇 |
1993年 | 369篇 |
1992年 | 43篇 |
1991年 | 88篇 |
1990年 | 53篇 |
1989年 | 67篇 |
1988年 | 65篇 |
1987年 | 66篇 |
1986年 | 67篇 |
1985年 | 49篇 |
1983年 | 7篇 |
1982年 | 24篇 |
1981年 | 40篇 |
1980年 | 62篇 |
1979年 | 9篇 |
1978年 | 17篇 |
1977年 | 137篇 |
1976年 | 317篇 |
1975年 | 11篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1964年 | 3篇 |
1960年 | 1篇 |
1956年 | 1篇 |
1955年 | 5篇 |
1954年 | 1篇 |
排序方式: 共有6497条查询结果,搜索用时 46 毫秒
991.
Adult attachment status, concurrent and early relationships with parents, and depressive symptoms were assessed in 53 adults. Individuals with consistent reports of relationships--positive or negative--were most coherent in their narratives. Depressive symptoms were associated with negativity in both recalled and current relationships with parents, but were not correlated with coherence of narratives. Clinical implications of the findings are discussed. 相似文献
992.
993.
994.
The insulin receptors from erythrocytes of 50 patients with non-insulin-dependent diabetes mellitus were tested for their ability to autophosphorylate. The assay was performed by a new enzyme-linked immunosorbent assay system that used monoclonal anti-insulin receptor antibodies absorbed to microtiter plates as a first antibody and polyclonal antiphosphotyrosine antibody as a labeled second antibody. By this assay, 3 patients were identified with defects in their insulin receptor kinase, although their defects appeared heterogeneous. Patient 1 had 85% less maximal autophosphorylation with a normal ED50 (1.6 x 10(-9) M insulin). Patient 2, who had polycystic ovary disease, had a 49.2% decrease in maximal autophosphorylation of insulin receptors, and the ED50 was shifted to the right (5.6 x 10(-8) M). Patient 3 with acanthosis nigricans had a normal maximal autophosphorylation, but the ED50 shifted to the right (2.9 x 10(-8) M). The mechanisms for the diversity detected in this assay is not known, but this technique has sufficient specificity and sensitivity to be used to screen for insulin-resistant patients who have a lack of kinase activity. 相似文献
995.
996.
The focal adhesion kinase (FAK) has been implicated in signal transduction pathways initiated by cell adhesion receptor integrins and by neuropeptide growth factors. To gain insight into FAK function, we examined the potential interaction of FAK with intracellular signaling molecules containing the Src homology 2 domains. We report here the stable association of FAK with phosphatidylinositol 3-kinase (PI3-kinase; EC 2.7.1.137) in NIH 3T3 mouse fibroblasts. This interaction was stimulated by cell adhesion concomitant with FAK activation. We also found that recombinant FAK bound to the p85 subunit of PI 3-kinase directly in vitro and that autophosphorylation of recombinant FAK in vitro increased its binding to PI 3-kinase. We detected increased tyrosine phosphorylation of the p85 subunit of PI 3-kinase during cell adhesion and observed direct phosphorylation of p85 by FAK in vitro. Together, these results suggest that PI 3-kinase may be a FAK substrate in vivo and serve as an effector of FAK. 相似文献
997.
The sampling of 50 microliters of the yolk (average 1.7% of the total volume) from northern bobwhite quail (Colinus virginianus) eggs on day 0, 6, 12, and 18 of incubation resulted in significantly (P < 0.05) increased embryo mortality in the day 12 and day 18 egg groups. Performance parameters and reproductive indices of the non-sampled eggs and the eggs sampled on day 0, and 6 of incubation did not differ from other reports on C. virginianus. No differences was found in postnatal responsiveness among hatchlings originating from controls and from all the groups of sampled eggs. As demonstrated in this representative galliform species, the technique can be applied for the screening of unembryonated eggs or early-embryogenesis-eggs of wild birds. If female birds are not accessible but their eggs are, information on the reproductive flock can be accessed without stressing adult birds. 相似文献
998.
999.
PG O'Malley JL Jackson K Kroenke K Yoon E Hornstein GJ Dennis 《Canadian Metallurgical Quarterly》1998,158(21):2357-2362
BACKGROUND: Musculoskeletal complaints are common and often unexplained and often lead to rheumatology referrals. The prevalence of psychiatric disease in patients with musculoskeletal complaints is unknown. OBJECTIVES: To determine the prevalence of common psychiatric disorders among patients referred to a rheumatology clinic and the likelihood of establishing a rheumatic diagnosis if a psychiatric disorder is present. DESIGN: Prospective diagnostic survey. SETTING: Two hospital-based rheumatology clinics and a general medicine clinic. PARTICIPANTS: A consecutive sample of newly referred patients (n = 185) and their rheumatologists (n = 9). INTERVENTION: Before their visit, all patients filled out a self-administered version of PRIME-MD (Primary Care Evaluation of Mental Disorders), a questionnaire that makes Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition: Primary Care Version, diagnoses of depressive, anxiety, and somatoform disorders. After the visit, the study rheumatologists, who were unaware of the PRIME-MD results, completed a questionnaire regarding their diagnostic assessment. These patients were compared with 210 patients with musculoskeletal complaints who were cared for in a general medicine clinic. MAIN OUTCOME MEASURES: Psychiatric and rheumatic disorders. RESULTS: Compared with patients with musculoskeletal complaints in a general medicine clinic, patients referred to a rheumatology clinic had a higher prevalence of psychiatric disease (40% vs 29%; P = .008), had an almost 2-fold higher prevalence of anxiety disorders, and were more likely to have multiple psychiatric disorders (odds ratio = 2.70, 95% confidence interval = 1.50-5.00). The likelihood of a psychiatric disorder differed among patients with connective tissue disease, nonsystemic articular or periarticular disorders, and nonarticular disorders (27%, 38%, 55%, respectively; P = .006). In a best-fitting logistic regression model, psychiatric disorders markedly decreased the likelihood of a connective tissue disease (odds ratio = 0.24, 95% confidence interval = 0.09-0.62). CONCLUSIONS: Forty percent of patients referred to a rheumatology clinic in this study had a psychiatric disorder, and its presence predicted a lower likelihood of a connective tissue disease. Prospective studies are needed to determine if screening for psychiatric disease before referring patients with unexplained musculoskeletal complaints would reduce costs or improve recognition of potentially treatable psychiatric disorders. 相似文献
1000.
JL Currie LA Mott SC Pennisi BD Smith RP Smith 《Canadian Metallurgical Quarterly》1997,176(5):1006-1008
OBJECTIVES: Our purpose was to assess the potential for an external vaginal antiitch cream (20% benzocaine, 3% resorcinol) to significantly increase levels of methemoglobin above normal in healthy women. STUDY DESIGN: Fifty-five women reporting external vaginal itch were recruited for the study. Each patient was used as her own control with methemoglobin levels being measured before and after use of the cream. Women were instructed to apply a 1-inch strip of cream by fingertip to the external genital area three or four times a day for 7 consecutive days. RESULTS: There were no significant differences in methemoglobin levels before and after use or in levels from a subgroup of women aged > 50 years compared with levels in a younger population. CONCLUSIONS: This preparation appears to be safe when used as directed; however, the results cannot be extrapolated to the very young. Nevertheless, lavish or frequent application over wide areas of excoriation might lead to toxic concentrations and methemoglobinemia. Therefore patients with serious vaginal disease should be advised against self-treatment beyond the 7-day limit imposed by the Food and Drug Administration for over-the-counter external analgesic medications. 相似文献