全文获取类型
收费全文 | 1991篇 |
免费 | 4篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 27篇 |
金属工艺 | 1篇 |
机械仪表 | 6篇 |
建筑科学 | 1篇 |
能源动力 | 2篇 |
轻工业 | 9篇 |
石油天然气 | 2篇 |
无线电 | 6篇 |
一般工业技术 | 4篇 |
冶金工业 | 1929篇 |
自动化技术 | 3篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 3篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 54篇 |
1998年 | 564篇 |
1997年 | 321篇 |
1996年 | 222篇 |
1995年 | 137篇 |
1994年 | 116篇 |
1993年 | 101篇 |
1992年 | 9篇 |
1991年 | 23篇 |
1990年 | 30篇 |
1989年 | 24篇 |
1988年 | 30篇 |
1987年 | 22篇 |
1986年 | 23篇 |
1985年 | 22篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 15篇 |
1979年 | 1篇 |
1978年 | 11篇 |
1977年 | 66篇 |
1976年 | 129篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1995条查询结果,搜索用时 15 毫秒
981.
We report six cases of intrauterine vascular deficiency of the upper limb, presenting over a 12-year period, with established areas of necrosis at the time of birth. Three of the six mothers were diabetic. An urgent examination of the neonate should be done to exclude occult systemic thomboses, as early anticoagulation or thrombolytic therapy may be indicated. The majority of cases were managed conservatively with dressings and splintage of the limb; exceptionally surgical intervention was required. Long-term sequelae included flexion contractures and shortening of the forearm bones. 相似文献
982.
983.
STUDY OBJECTIVE: To compare withholding warfarin therapy with low-dose (2.5 mg) oral vitamin K therapy in excessively anticoagulated patients without bleeding complications. DESIGN: Prospective and retrospective studies. SETTING: Anticoagulation clinic at a Veterans Affairs institution. PATIENTS: Twenty-eight men were matched according to initial international normalized ratio (INR) and INR goal ranges. INTERVENTIONS: The retrospective arm of the study consisted of chart reviews of overanticoagulated patients whose warfarin doses were held until therapeutic INR values were reached. The prospective arm included overanticoagulated patients who were administered a single 2.5-mg dose of oral vitamin K. MEASUREMENTS AND MAIN RESULTS: Mean days to therapeutic INR values were 2.3+/-0.6 and 1.4+/-0.6 (p=0.001), and mean reduction in INR 1 day after treatment intervention was 1.32+/-0.79 and 3.46+/-1.31 (p<001) U for the withholding and vitamin K groups, respectively. CONCLUSION: Compared with withholding the warfarin dose, administration of 2.5 mg of oral vitamin K to excessively anticoagulated patients receiving warfarin significantly reduced the time required to reach a therapeutic INR as well as final INR. 相似文献
984.
The influence of timing of surgery in relation to menstrual period on survival of breast cancer patients has been both advanced advocated and disputed. A meta-analysis on published series showed a statistically significant overall odds reduction when surgery is performed in the luteal phase. The records of 165 premenopausal M- breast cancer women, not on hormonal therapies, consecutively operated on from 1977 to 1991 were reviewed. All patients underwent modified radical mastectomies or quadrantectomies plus operative radiotherapy, Node-positive patients received standard adjuvant chemotherapy. Cox regression analysis was used to estimate the relative risk (RR) of death in three models including timing of surgery, age, histology, pathological T and N. In each model, patients were divided into two groups according to the criteria proposed by Badwe, Hrushesky, and Senie. Multivariate analysis showed a significant association between pT and pN and survival, whereas no association with survival was observed for timing of surgery according to Badwe or Hrushesky or Senie criteria (RR = 1.26, RR = 0.91, and RR = 0.88 respectively). Up-to-date agreement on the menstrual phase and relative expected better prognosis is still lacking. 相似文献
985.
AP Koets 《Canadian Metallurgical Quarterly》1995,17(1):21-29
The function of eCG in equine pregnancy is far from clear but it has become evident that eCG has little or no FSH activity in the horse and is therefore probably not responsible for the secondary ovulations. eCG does have luteotrophic activity and it could play a role in the resurgence of the primary corpus luteum (1,7,44). Some evidence exists that the receptor population on the equine gonads is heterogenous in a way that makes it possible to distinguish eCG from eLH, resulting in different post-receptor effects (7). There is also evidence that eCG itself is heterogenous, both in glycosylation and in primary structure, not only between different individual animals but also within one animal during different stages of gestation. The differences could simply reflect the difference between stored and secreted hormone, but on the other hand the release of different eCG forms could be under endocrine control, allowing the mare to produce forms appropriate to specific biological needs (74). Thus some forms of eCG could play a role in immunological events taking place at the foeto-maternal interface. The role of cytotoxic antibodies in the equine pregnancy is not understood. The fact that they are not harmful to the pregnancy can be explained by the fact that their target, the paternal MHC molecules, are withdrawn from the endometrial cup tissue by the time the antibodies start appearing in the circulation. This unique way of regulation of MHC expression is also poorly understood.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
986.
987.
AP Goringe S Brown U O''Callaghan J Rees S Jebb M Elia CH Poynton 《Canadian Metallurgical Quarterly》1998,21(8):829-832
PURPOSE: To analyze the nonfatal adverse events (AE) associated with a first episode of status epilepticus (SE). METHODS: We performed a population-based retrospective cohort study to determine the morbidity of SE. Participants included 184 residents of Rochester, Minnesota who experienced nonfebrile SE between 1965 and 1984. RESULTS: The etiology of SE was acute symptomatic in 100 patients and unprovoked in 84 patients. The most common seizure-types were continuous partial (n=56, 30%), generalized convulsive (n=52, 28%), and generalized with focal features (n=32, 17%). Morbidity related to SE was noted in 5 of the 146 patients (3.4%) surviving 30 days. The AE included hemiparesis (n=3), encephalopathy (n=2), mental retardation (n=1), and aphasia (n=1). All patients with morbidity had an acute symptomatic (n=4) or remote symptomatic (n=1) etiology. Thirty-four patients (18.5%) had a second episode of SE. CONCLUSIONS: Based on this retrospective study, significant morbidity related to SE is uncommon and is associated with the underlying etiology. 相似文献
988.
Primary care of girls between the ages of 10 and 20 presents some unique challenges. This article presents a review of normal adolescent development and explores preventive health issues and some of the more common acute medical problems of adolescent girls. Counseling on some behavioral and psychosocial issues also is discussed. Finally, anticipatory guidance topics to be discussed with parents are included. 相似文献
989.
EE Haddad CE Whitfill AP Avakian CA Ricks PD Andrews JA Thoma PS Wakenell 《Canadian Metallurgical Quarterly》1997,41(4):882-889
Two experiments were conducted to test the efficacy of a novel infectious bursal disease virus (IBDV) vaccine in broiler chickens with maternal IBDV immunity. The IBDV vaccine was formulated by mixing IBDV strain 2512 with bursal disease antibodies (BDA) to produce the IBDV-BDA complex vaccine. In Expt. I, 1-day-old Cobb x Cobb broiler chickens were vaccinated subcutaneously with either IBDV-BDA or commercial live intermediate IBDV vaccine (vaccine A) or were left unvaccinated. In Expt. 2, the vaccine A group was not included; instead, IBDV strain 2512 was included. Chickens were maintained in isolation houses. On day 28 (Expt. 1) and day 32 (Expt. 2) of age, chickens from each group were challenged with a standard USDA IBDV (STC strain) challenge. Challenged and unchallenged chickens were evaluated for their bursa/body weight ratios and antibody titers 3 days post-challenge. Bursae collected from Expt. 2 were examined histologically to evaluate bursal lesions and confirm gross examination. None of the unvaccinated chickens was protected against the challenge virus as evidenced by the presence of acute bursal lesions (edema/hemorrhage). All chickens receiving the IBDV-BDA complex or the IBDV strain 2512 (Expt. 2) were protected from the challenge virus as evidenced by no acute bursal lesions. Additionally, chickens receiving the IBDV-BDA complex vaccine or the IBDV strain 2512 had antibody titers to IBDV, indication the presence of an active immune response. In Expt. 1, chickens vaccinated with vaccine A and challenged had bursal lesions similar to those observed in the unvaccinated, challenged chickens. These chickens also showed no indication of active immunity against the virus. These results suggest that the 1-day-of-age-administered IBDV-BDA complex vaccine can induce active immunity and protection against a standard IBDV challenge in the face of variable levels of maternal IBDV immunity. 相似文献
990.