全文获取类型
收费全文 | 2173篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 61篇 |
金属工艺 | 4篇 |
机械仪表 | 9篇 |
建筑科学 | 14篇 |
矿业工程 | 1篇 |
能源动力 | 2篇 |
轻工业 | 17篇 |
无线电 | 32篇 |
一般工业技术 | 52篇 |
冶金工业 | 1940篇 |
原子能技术 | 4篇 |
自动化技术 | 36篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 21篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 9篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 63篇 |
1998年 | 663篇 |
1997年 | 332篇 |
1996年 | 226篇 |
1995年 | 115篇 |
1994年 | 118篇 |
1993年 | 120篇 |
1992年 | 13篇 |
1991年 | 19篇 |
1990年 | 30篇 |
1989年 | 29篇 |
1988年 | 28篇 |
1987年 | 23篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 20篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 41篇 |
1976年 | 91篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1959年 | 1篇 |
1955年 | 2篇 |
1925年 | 1篇 |
排序方式: 共有2177条查询结果,搜索用时 15 毫秒
71.
Previous data have shown that reducing agents disrupt the structure of vaccinia virus (vv). Here, we have analyzed the disulfide bonding of vv proteins in detail. In vv-infected cells cytoplasmically synthesized vv core proteins became disulfide bonded in the newly assembled intracellular mature viruses (IMVs). vv membrane proteins also assembled disulfide bonds, but independent of IMV formation and to a large extent on their cytoplasmic domains. If disulfide bonding was prevented, virus assembly was only partially impaired as shown by electron microscopy as well as a biochemical assay of IMV formation. Under these conditions, however, the membranes around the isolated particles appeared less stable and detached from the underlying core. During the viral infection process the membrane proteins remained disulfide bonded, whereas the core proteins were reduced, concomitant with delivery of the cores into the cytoplasm. Our data show that vv has evolved an unique system for the assembly of cytoplasmic disulfide bonds that are localized both on the exterior and interior parts of the IMV. 相似文献
72.
Adenocarcinoma of the gallbladder combined with a malignant peripheral nerve sheath tumor (MPNST) in the gallbladder in an 81-year-old woman is reported. The resected gallbladder showed two distinct tumor components, the epithelioid type of MPNST and adenocarcinoma with areas of mucin production. Although the immediate postoperative course was uneventful, a pathologic fracture of her right upper femur developed 4 months after the cholecystectomy. The pathology was determined to be a feature of metastatic MPNST rather than of adenocarcinoma. A whole body bone scan revealed multiple metastases, including the left parietal skull, left ninth rib, seventh thoracic vertebra, and right upper third of the femur. Despite cholecystectomy and postoperative irradiation therapy, she died 6 months after diagnosis of the tumor. Without an autopsy the primary site of the MPNST was unknown. We found that the prognosis was very poor in patients with distal metastatic MPNST, especially in older patients. 相似文献
73.
One of the important components of successful anemia therapy in patients with end-stage renal disease (ESRD) treated with recombinant human erythropoietin is the maintenance of adequate available iron. To accomplish this task, iron status must be serially monitored and supplemental iron administered as required. Among nonuremic subjects, the body's iron supply is tightly conserved, and iron deficiency usually develops only when chronic blood loss occurs. In patients with ESRD, iron deficiency occurs more frequently, because of increased external losses of iron, decreased availability of the body's storage of iron, and perhaps a deficit in intestinal iron absorption. Detecting iron deficiency in these patients can be difficult because of the inaccuracy of available diagnostic tests. The goals of iron therapy in ESRD include the prevention of iron deficiency by chronically supplementing iron, and the prompt treatment of overt iron deficiency. Oral iron supplements are inexpensive and safe, but poor patient compliance and reduced intestinal absorption may limit their effectiveness. Intravenous iron supplements have a greater efficacy then oral iron, which must be weighed against the small risk of allergic reactions. We present strategies for using the various diagnostic tests and treatment modalities to effectively manage iron supply for predialysis, hemodialysis, and peritoneal dialysis patients. 相似文献
74.
Elastofibroma, or elastofibroma dorsi as it was first described, is an uncommon tumor-like process that characteristically appears as an ill-defined mass in the infrascapular region of elderly patients. This lesion can occur bilaterally and may appear asynchronously. The occurrence of elastofibroma in other anatomic sites has been reported, although with much less frequency. Elastofibromas display typical diagnostic histologic, cytologic, and electron microscopic features. The use of magnetic resonance imaging can lead to a presumptive diagnosis in elderly individuals with suprascapular lesions. It is important to differentiate this lesion from other soft-tissue lesions, such as sarcomas and desmoid tumors. This study presents a case of bilateral elastofibromas in a 72-year-old man and a review of the literature. 相似文献
75.
JK Slap 《Canadian Metallurgical Quarterly》1998,68(4):923-924
76.
77.
78.
DE Anderson G St-Jean DC Richardson RM DeBowes JK Roush SR Lowry PW Toll HM Aberman DC Van Sickle JJ Hoskinson 《Canadian Metallurgical Quarterly》1997,68(6):571-576
The analysis of health state of drivers sent for an extra health examination for the estimation of driving capability for the driving of motor vehicle in alcoholic state was presented. The study included 380 drivers who were found driving drunk by traffic police (studied group) and 180 drivers of control group sent for an extra health examination for some other reason. The disorders in psychomotor sphere were noticed in the drivers of studied group and it was determined that they had caused significantly larger number of traffic accidents in last five-year period compared to the drivers of control group. The alcohol consumption in driving population represents significant medical, social, economic and traffic problem. The control of driver's alcoholism, the sending of alcoholic drivers to an extra health examination for the repeated estimation of driving capability and including in therapeutic and health-educational program can present significant measure of the primary prevention of road traffic traumatism which is on the constant increase. 相似文献
79.
JK Bernard 《Canadian Metallurgical Quarterly》1997,80(5):938-942
Two 3 x 3 Latin square trials were conducted to determine the effect of the source of supplemental protein in diets containing wheat middlings on milk production and composition. Cottonseed meal or meat and bone meal was substituted for a portion of the soybean meal and provided 24.5% of the total dietary crude protein. Trial 1 was conducted during fall 1989, and trial 2 was conducted during summer 1993. During trial 1, no differences in production or composition of milk were found for primiparous cows fed the various protein supplements. Multiparous cows tended to have higher dry matter intakes and produced more milk with lower milk fat percentages when fed meat and bone meal than when fed soybean meal or cottonseed meal. No differences were found among supplements for other milk components or for the production of energy-corrected milk. In trial 2, primiparous cows tended to produce more milk, and multiparous cows tended to produce less milk, when fed meat and bone meal than when fed soybean meal. No differences were found for dry matter intake, milk composition, or production of energy-corrected milk. Cottonseed meal was equal to soybean meal in supporting milk production. Meat and bone meal tended to support higher productions of milk than did soybean meal, but production of energy-corrected milk was similar for both. 相似文献
80.