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   2442篇
  免费   2篇
综合类   2篇
化学工业   4篇
机械仪表   1篇
建筑科学   1篇
轻工业   1篇
石油天然气   1篇
一般工业技术   5篇
冶金工业   2427篇
自动化技术   2篇
  2022年   2篇
  2019年   1篇
  2018年   2篇
  2016年   1篇
  2013年   1篇
  2009年   1篇
  2007年   1篇
  2006年   1篇
  2003年   3篇
  2001年   1篇
  2000年   1篇
  1999年   70篇
  1998年   746篇
  1997年   417篇
  1996年   299篇
  1995年   148篇
  1994年   129篇
  1993年   143篇
  1992年   13篇
  1991年   23篇
  1990年   25篇
  1989年   21篇
  1988年   22篇
  1987年   21篇
  1986年   16篇
  1985年   13篇
  1984年   1篇
  1983年   7篇
  1982年   14篇
  1981年   14篇
  1980年   23篇
  1979年   3篇
  1978年   9篇
  1977年   61篇
  1976年   176篇
  1975年   4篇
  1973年   2篇
  1965年   1篇
  1964年   3篇
  1963年   1篇
  1960年   1篇
  1955年   3篇
排序方式: 共有2444条查询结果,搜索用时 15 毫秒
21.
Gonadal hormones affect body composition, food intake, weight gain and serum lipids in numerous species including man. In this study, mature male Sprague-Dawley rats were castrated or sham-operated at 16 weeks of age. During the 6-week observation period with weekly records of food intake and weight gain, these parameters were significantly lower in the castrated group. The decrease in food intake in this group could not account for the difference in body weight between the groups, indicating a lower feed utilisation in the castrates. At sacrifice accessory reproductive organs, the levator ani muscle, thymus and adrenals were dissected for determination of organ weight and histology, revealing significant reductions in the accessory reproductive organs and levator ani of the castrates. The thymus was significantly heavier in the castrated animals. No differences were found in the adrenals. Two of the sham-operated animals had signs of accidental functional castration. The proportion of body cell mass and total lipid of the carcass was the same in both groups. Significant reductions in adipocyte weights were found in the epididymal depots of the castrated rats. Blood samples taken at sacrifice in pentobarbital anaesthesia were analysed for glucose, insulin, triglycerides, cholesterol, FFA, glycerol and protein. Statistically significant reductions in triglycerides and protein were recorded in the castrated animals without any significant changes in the other parameters studied. The results are discussed with reference to the age of castration and the importance of the reduced food intake in castrated animals.  相似文献   
22.
We have used dacryoscintigraphy to study the efficiency of the lacrimal system following the repair of a divided lower canaliculus in 4 children. This test has been reliable in evaluating lacrimal function and suggests that a canaliculus can be repaired and splinted satisfactorily. Our experience with dacryoscintigraphy confirms that it is a safe comfortable, and reliable method for studying the patency of the lacrimal drainage system.  相似文献   
23.
Using Wistar stain male rats, it has been shown that 2 atmospheric pressures associated with oxygen saturation, together or singly for 90 minutes daily for successive 46 days, resulted in no significant change on the ratio of testes to body weight. No significant change was observed in the incorporation of 3H-thymidine into testes and pituitary glands between the pressure-treated groups and the control group.  相似文献   
24.
25.
It was intendet to characterize the isoenzymes of serum alkaline phosphatase in healthy infants. Quantitative estimation of the activity of serum alkaline phosphatase resulted in relatively low values in the newborns and a distinct increase during the first three months of live. As a rule most of the newborns appeared to present one uniform isoenzyme fraction, which was comparable to the isoenzyme of bone origin of the adult. Some of the newborns already exhibited another less marked isoenzyme, the isoenzyme of liver origin. During babyhood this isoenzyme becomes more and more distinct. In most cases this development had become perfect at the end of the first year. Liver tissue of newborns apparently does not synthesize the same liver isoenzyme as liver tissue of adults.  相似文献   
26.
The results of a 1974 survey of albumin measurements as performed by more than 1,300 laboratories are presented. The most widely used methods are the dye-binding technics: bromcresol green (BCG) and 2-(4'-hydroxyazobenzene) benzoic acid (HABA). These are followed by electrophoresis and salt fractionation. All methods yielded comparable albumin concentrations except electrophoresis, which manifested a consistent low bias. This close agreement is attributed, in part, to the normal-range concentration of albumin in the test specimen. Type of standardization, i.e., commercial serum, bovine serum albumin, human serum albumin, or pooled serum, did not appear to be a factor in the estimation of albumin in the normal serum submitted for analysis. Surprisingly, interlaboratory variation, from method means, was the lowest for salt fractionation and electrophoretic technics.  相似文献   
27.
Seventy cases of ectopic pregnancy associated with an IUD comprised 10% of all ectopics in a 9 year period. This increased to 15% in the last 19 months as more IUD's were in use. In two thirds of the ectopics the IUD had been in situ more than 1 year. Unusual bleeding and cramping attributed to the IUD obscured the diagnosis and resulted in removal or replacement of the IUD in over one half the cases 1 to 8 weeks before surgery. The episodic nature of the abdominal hemorrhage in two thirds of all ectopics resulted in surgery on day 44 average gestational age. The IUD is probably not causal in ectopic pregnancy but does not protect the predisposed patient from ectopic pregnancy which should be suspected in any patient with an IUD who has irregular bleeding and abdominal pain.  相似文献   
28.
The anatomic relationship of the 2 major vessels of the left coronary groove was studied in 140 dogs. Five basic patterns of disposition were observed: 1) circumflex artery superficial from its origin to the caudodorsal cardiac margin, coronary vein deep and not visible (22%); 2) coronary vein superficial from the ventral interventricular septum to the caudodorsal cardiac margin, circumflex artery deep and not visible (15%); 3) circumflex artery and coronary vein both superficial and running parallel with each other along the groove (8%); 4) coronary vein crossing circumflex artery at some point along the groove (44%); and 5) circumflex artery crossing coronary vein at some point along the groove (11%). These variations were found to influence certain experimental modifications of the left circumflex blood flow in the dog.  相似文献   
29.
X-ray fiber diffraction studies of satellite DNAs from Gecarcinus lateralis, Drosophila virilis and Mus musculus, all of which have highly repetitious base sequences but with different degrees of sequence complexity, reveal only classical polynucleotide duplex structures in contrast to some highly repetitious synthetic DNAs.  相似文献   
30.
Women's attitudes to mastectomy for breast cancer   总被引:1,自引:0,他引:1  
One hundred patients who had been subjected to mastectomy for carcinoma were interviewed retrospectively to gauge their attitudes to any physical and/or emotional disabilities relating to their operation or disease. It was found that 40% of the patients had delayed for longer than a month after the onset of symptoms before seeking medical advice, but the reasons for this were not readily forthcoming. However, fear of mastectomy was not a common cause. Anxiety and embarassment due to an absent breast occurred in about one-third of patients, and did not diminish with time. Knowledge and the use of mammary prostheses was far from universal, and disturbingly only two-thirds were counselled in these matters by their medical advisers. Physical complications were common, particularly lymphoedema of the arm, and as expected this was closely related to the type and extent of treatment undertaken.  相似文献   
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