首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1322篇
  免费   4篇
  国内免费   1篇
化学工业   3篇
金属工艺   1篇
机械仪表   3篇
建筑科学   1篇
轻工业   1篇
石油天然气   2篇
无线电   5篇
一般工业技术   2篇
冶金工业   1308篇
自动化技术   1篇
  2019年   2篇
  2017年   1篇
  2016年   3篇
  2014年   1篇
  2012年   2篇
  2011年   1篇
  2008年   1篇
  2003年   6篇
  1999年   31篇
  1998年   443篇
  1997年   264篇
  1996年   139篇
  1995年   88篇
  1994年   57篇
  1993年   76篇
  1992年   10篇
  1991年   24篇
  1990年   26篇
  1989年   19篇
  1988年   22篇
  1987年   14篇
  1986年   13篇
  1985年   9篇
  1983年   2篇
  1982年   3篇
  1981年   4篇
  1980年   11篇
  1978年   2篇
  1977年   16篇
  1976年   37篇
排序方式: 共有1327条查询结果,搜索用时 62 毫秒
71.
72.
We conducted studies to determine at what time point an add-on prothrombin time (PT) or activated partial thromboplastin time (APTT) test can be honored on specimens that have been received in the laboratory hours earlier without yielding results with clinically significant differences from those if the test had been performed on the original unstored plasma. PT and APTT tests were performed on blood samples from 20 healthy subjects, 30 patients receiving warfarin, and 30 patients receiving heparin anticoagulation therapy. The tests were performed on plasma prepared initially after the samples were obtained. The same tests were assayed on plasma that had been left on spun-down blood cells at room temperature for 2, 4, and 8 hours. We found that the PT of the majority of plasma samples from healthy subjects and from patients receiving oral anticoagulant therapy tended to become shorter on storage. However, the difference in PT values was small and had no clinical significance. In most cases, the APTT values for the stored plasma from healthy subjects tended to increase with time. Except in one specimen in which the 8-hour add-on APTT was 1.2 seconds longer than the APTT result for the original sample, all others had APTT results less than 1.2 seconds longer than the original values. In patients receiving heparin, the differences in APTT values between the initial and add-on tests were larger than those observed for healthy subjects. However, those differences are not beyond what we would accept for duplicate checks for heparinized samples with high APTT values. Unlike samples from healthy subjects, there was no obvious trend of time-related prolongation of the APTT in heparinized plasma. These results led us to believe that within an 8-hour period and with plasma on spun-down cells at room temperature, add-on tests for PT and APTT could be performed with results similar to what would be obtained from testing unstored samples.  相似文献   
73.
Nickel biochemistry   总被引:1,自引:0,他引:1  
We present a method for the determination of the lignan enterolactone in plasma (serum). This compound, produced by intestinal bacteria from matairesinol and secoisolariciresinol in fiber-rich food, is a biomarker related to the intake of a healthy diet. The method is based on time-resolved fluoroimmunoassay using a europium chelate as a label. After synthesis of 5'-O-carboxymethoxyenterolactone the compound is coupled to bovine serum albumin and then used as antigen in immunization of rabbits. The tracer with the europium chelate is synthesized using the same 5'-derivative of enterolactone. After enzymatic hydrolysis and ether extraction the immunoassay is carried out using the VICTOR 1420 multilabel counter (Wallac Oy, Turku, Finland). No antiserum cross-reactivity with available lignans, isoflavonoids, or flavonoids could be detected. The intraassay and interassay coefficients of variation at different concentrations vary 4.6-6.0 and 5.5-9.9, respectively. The working range of the assay is 1.5-540 nmol/liter. We measured enterolactone in serum/plasma of 224 Finnish subjects: 98.8% of the subjects had values <100 nmol/liter, 38.0% had 20-39.9 nmol/liter, and 34.4% had <20 nmol/liter.  相似文献   
74.
The author describes the operating course of the Occupational Medicine Operating Units (OMOU) in our region. (Lombardia) These Units, born as a second level support to the Basal Occupational Medicine Units, greatly enlarged, as time passed, the limits of their users together with the charge of preventive duties ordered to the employers by the recent laws regarding Occupational Hygiene. (DLgs 277/91-DLgs 626/94) The author also illustrates the variety of the diagnostic demands to the OMOU according to the enlargement of the legal protection of occupational diseases and to the numerous aspects of specific job fitness. He underlines the need of multiple specialistic skillfulnesses achievable by means of a complete integration of OMOU in to the hospital to which they belong. In conclusion the author illustrates the new tasks of the OMOU in the field of the therapy and rehabilitation.  相似文献   
75.
76.
We evaluated the role of intravascular ultrasound (IVUS) in 16 patients with unprotected left main coronary artery (LMCA) stenting compared with 80 patients with other (non-LMCA) native coronary artery stenting and found that (1) additional high-pressure or larger size balloon dilations were more frequently performed in LMCA stenting than in non-LMCA stenting (p <0.05) and (2) after IVUS-guided stent implantation, minimum lumen area was > or = 9 mm2 in 88% of patients who underwent LMCA stenting and in 19% of those who underwent non-LMCA stenting (p <0.001). IVUS guidance may be a more important adjunctive imaging modality in the stenting of unprotected LMCA stenoses than in stenting of non-LMCA stenoses.  相似文献   
77.
We have used extracorporeal membrane oxygenation (ECMO) for 28 patients (14 children and 14 adults) over a 5 year period. Nine patients improved on ECMO and 5 were long-term survivors. ECMO was used for pulmonary insufficiency in 24 patients. Initially, only moribund patients were treated, but recently the combination of open lung biopsy and pulmonary insufficiency index (PII) has been used to select patients. The best results have been obtained in newborn cases and the adult capillary leak syndromes; the major problem has been progression to fibrosis despite ECMO support. ECMO was used for cardiac failure in 4 patients. Children with postoperative cardiac failure did the best; profound shock was not reversed with venoarterial bypass. ECMO support is lifesaving in selected cases of pulmonary insufficiency. Initial trials in cardiac failure and the infant age group in this series suggest that ECMO will have an even greater role in those applications.  相似文献   
78.
79.
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号