全文获取类型
收费全文 | 1448篇 |
免费 | 1篇 |
专业分类
化学工业 | 2篇 |
金属工艺 | 4篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
轻工业 | 3篇 |
石油天然气 | 1篇 |
无线电 | 30篇 |
一般工业技术 | 64篇 |
冶金工业 | 1337篇 |
原子能技术 | 5篇 |
出版年
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 28篇 |
2017年 | 21篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 38篇 |
1998年 | 438篇 |
1997年 | 208篇 |
1996年 | 173篇 |
1995年 | 74篇 |
1994年 | 64篇 |
1993年 | 89篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 18篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 56篇 |
1976年 | 85篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1449条查询结果,搜索用时 0 毫秒
31.
32.
CF Chang LJ Kiser JE Bailey M Martins WC Gibson KA Schaberg DM Mirvis WB Applegate 《Canadian Metallurgical Quarterly》1998,279(11):864-869
In July 1996, Tennessee initiated a managed mental health and substance abuse program called TennCare Partners. This publicly funded "carve-out" experiment started chaotically and soon deteriorated into a crisis. Many patients did not receive care or lost continuity of care, and the traditional "safety net" mental health system nearly disintegrated. This qualitative case study sought to ascertain the impact of the TennCare Partners program. It points out that the program's difficulties stemmed directly from a flawed design that spread funds previously earmarked for severely mentally ill patients across the entire Medicaid population. States contemplating similar reforms should strive to protect vulnerable patients by risk-adjusting capitation payments and by focusing resources on care for severely mentally ill persons. States should also minimize program complexity and ensure the accountability of managed care networks for their patients' behavioral health care needs. 相似文献
33.
S Migliaccio S Bernardini WC Wetsel KS Korach T Faraggiana A Teti 《Canadian Metallurgical Quarterly》1998,63(5-6):352-354
Ventriculo-peritoneal shunts (VPS) are the most frequent operative procedures used to treat hydrocephalic children. Abdominal complications of VPS are now a rare event; however, their frequency varies from 5% to 47% according to reports. Anything that causes an obstruction or impediment of the VP derivation system will lead to intracranial hypertension, which requires immediate surgery. From 1985 to 1995 at the Division of Pediatric Surgery of the Federico II University of Naples, ten laparoscopies were performed in ten children with VPS complications. Cerebrospinal fluid pseudocysts were found in four infants. There was one case of abdominal wall perforation by the tip of the catheter at the umbilical level, two bowel obstructions, and one catheter was lost in the abdominal cavity. Finally, two children had malfunctioning of the peritoneal limb of the catheter. The laparoscopic technique was curative in all ten cases, thus avoiding a conventional laparotomy and the consequent risk of adhesions, which could cause further complications. 相似文献
34.
Analysis of the S-phase fractions (SPF) measured by in vitro thymidine labeling, morphological appearances, and estrogen receptor (ER) assays of primary invasive breast carcinomas demonstrated several interrelationships. Lobular, mucinous, tubular, and adenocystic carcinomas consistently had low SPF and were usually positive for ER. The same was true for the carcinomas of no special histologic type [the not otherwise specified (NOS) group of E. R. Fisher including "infiltrating ductal" and undifferentiated carcinomas] with minimal anaplasia. Medullary, atypical medullary, and morphologically unclassifiable carcinomas with marked nuclear anaplasia nearly always had high SPF and were usually negative for ER. High SPF was associated with advanced stages of carcinoma initially or with early recurrence following mastectomy. 相似文献
35.
Predictability of healing of ischemic leg ulcers by radioisotopic and Doppler ultrasonic examination
In a prospective study of twenty-six patients with ischemic ulcerations of the lower extremity, the predictive reliability with regard to spontaneous wound healing of diabetes, pedal pulses, ankle blood pressure (ABP) as measured by doppler ultrasound, and "leg ulcer scan" as performed by the intra-arterial injection of radioactive albumin was evaluated. The results suggest that only the leg ulcer scan is significantly reliable in predicting the likelihood of spontaneous healing. The following format for the evaluation of the ischemic leg ulcer is therefore suggested: (1) If pedal pulses are present, a three week trial of conservative therapy is indicated before further evaluation. (2) If the doppler ABP is 50 mm Hg or less, the ulcer will not heal spontaneously. (3) Leg ulcer scan is indicated: (a) in the absence of pedal pulses if ABP is less than 50 mm Hg; (b) in the presence of pedal pulses if there is no evidence of spontaneous healing after three weeks of conservative therapy. 相似文献
36.
WC Stevens 《Canadian Metallurgical Quarterly》1976,55(5):622-625
Experiments were performed on obligatory bipeds to study the effects of an arteriovenous fistula on a devascularized ischemic limb. Retrograde flow of arterial blood entering the venous system by way of an arteriovenous fistula was demonstrated. Venous valves appeared not to interfere with retrograde arterial flow. The data from these experiments indicate that a "Y" type arteriovenous fistula can lead to functional revascularization in the ischemic limb with arterial obstruction. The dual mechanism of retrograde arterial flow in venous channels and the stimulation of collateral flow adjacent to the fistula seemed to be critical factors. Since a peripheral arteriovenous fistula is a potent stimulus to arterial collateralization in the extremity, its application is worthy of consideration in certain selected patients with advanced and otherwise inoperable arterial occlusive disease. 相似文献
37.
Cordelia Sealy 《Materials Today》2017,20(5):227-228
38.
Cordelia Sealy 《Materials Today》2017,20(10):559-560
39.
40.
Exposure of mammalian cells to ultraviolet (UV) light elicits a cellular response and can also lead to apoptotic cell death. In this report, we show that a 36-kDa myelin basic protein (MBP) kinase detected by an in-gel kinase assay can be dramatically activated during the early stages of UV irradiation-triggered apoptosis of A431 cells. Immunoblot analysis revealed that this 36-kDa MBP kinase could be recognized by an antibody against the C-terminal regions of a family of p21Cdc42/Rac-activated kinases (PAKs). By using this antibody and a PAK2-specific antibody against the N-terminal region of PAK2 as studying tools, we further demonstrated that UV irradiation caused cleavage of PAK2 to generate a 36-kDa C-terminal catalytic fragment and a 30-kDa N-terminal fragment in A431 cells. The appearance of the 36-kDa C-terminal catalytic fragment of PAK2 matched exactly with the activation of the 36-kDa MBP kinase in A431 cells upon UV irradiation. In addition, UV irradiation also led to activation of CPP32/caspase-3, but not ICH-1L/caspase-2 and ICE/caspase-1, in A431 cells and the kinetics of activation of CPP32/caspase-3 appeared to correlate well with that of DNA fragmentation and of cleavage/activation of PAK2, respectively. Moreover, blockage of activation of CPP32/caspase-3 by pretreating the cells with two specific tetrapeptidic inhibitors for caspases (Ac-DEVD-cho and Ac-YVAD-cmk) could significantly attenuate the extent of cleavage/activation of PAK2 induced by UV irradiation. Collectively, the results demonstrate that cleavage and activation of PAK2 can be induced during the early stages of UV irradiation-triggered apoptosis and indicate the involvement of CPP32/caspase-3 in this process. 相似文献