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   938篇
  免费   2篇
轻工业   2篇
一般工业技术   3篇
冶金工业   935篇
  2018年   1篇
  2016年   1篇
  2003年   2篇
  2000年   1篇
  1999年   29篇
  1998年   290篇
  1997年   165篇
  1996年   95篇
  1995年   61篇
  1994年   69篇
  1993年   55篇
  1992年   4篇
  1991年   4篇
  1990年   3篇
  1989年   7篇
  1988年   7篇
  1987年   8篇
  1986年   6篇
  1985年   6篇
  1983年   2篇
  1982年   2篇
  1981年   7篇
  1980年   11篇
  1979年   1篇
  1978年   3篇
  1977年   30篇
  1976年   68篇
  1975年   1篇
  1954年   1篇
排序方式: 共有940条查询结果,搜索用时 15 毫秒
931.
932.
PUVA is used to treat severe skin problems that have not responded well to more conventional forms of treatment. The effectiveness of PUVA therapy depends on patient compliance and careful administration and evaluation of patient response to treatment. The following protocol was developed to identify important factors to consider when administering PUVA therapy.  相似文献   
933.
A case is presented which demonstrates the value of bronchial arteriographic studies in localizing and treating hemoptysis. The patient was bleeding from an old post-tuberculous bulla and for several reasons was not a candidate for surgery. Bronchial arteriographic studies demonstrated both hypervascularity in the region of the cavity and also a mycotic aneurysm of a bronchial artery. After therapeutic embolization with gelatin (Gelfoam), the hypervascularity and aneurysm were no longer opacified. Active bleeding abruptly ceased and, except for a single mild recurrence, has not recurred during the three months since therapeutic embolization. The major theoretic risk of bronchial arteriographic study and therapeutic embolization is spinal injury. It is believed that permanent injury can almost be avoided, providing proper technique is used.  相似文献   
934.
935.
936.
Sera from cystic fibrosis (CF) homozygotes and obligate heterozygotes contain a CF factor (gamma CF factor) not found by isoelectric focusing in thin-layer polyacrylamide gels in most normal control sera. In addition, sera from most obligate heterozygotes lack another protein (bland B, C, or D) that is commonly found in sera from most normal and cystic fibrosis individuals. A standardized, biophysical assay is described that employs isoelectric focusing for the detection of both CF homozygotes and heterozygotes based on the analysis of whole serum for the presence of the gamma CF factor and bands B, C, and D. Results of analyzing sera from selected CF patients by isoelectric focusing indicated that there is a general correlation between the amount of the gamma CF factor and the clinical severity of the disease. Partial purification and characterization of the gamma CF factor and protein bands B, C, and D was accomplished by using DEAE-cellulose chromatography, Sephadex G-200 gel filtration, sequential molecular filtration through a series of Amicon Diaflo ultrafiltration membranes, affinity chromatography, and cellulose acetate electrophoresis. The gamma CF factor is a cationic protein with a pI of 8.46+/-0.05, has gamma electrophoretic mobility, a molecular weight between 3,500 and 10,000, and apparently exists in CF serum in 2 forms (free in solution and complexed to IgG). Bands B, C, and D are cationic proteins with pI values of 7.85 to 8.10, have gamma electrophoretic mobility and a molecular weight of approximately 100,000-150,000.  相似文献   
937.
938.
A direct binding enzyme-linked immunosorbent assay (ELISA) was established for quantitative determination of serum IgM antibodies towards a synthetic peptide corresponding to a selected segment (14-21) of the preS2-gene product containing an immunodominant linear B-cell epitope. The prevalence of IgM anti-preS2 (14-21) antibody titers > 1,000 for hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis B virus (HBV) infection was 38% (22/58) and 10% (2/21) for HBeAg-negative subjects (P < 0.005). IgM anti-preS2 (14-21) reactivity was detected during the clinical course of chronic HBV infection and IgM anti-peptide antibody titers declined and disappeared before spontaneous HBe/anti-HBe seroconversion. Recombinant interferon (IFN)-alpha 2b with an antecedent short course of corticosteroids was administered to eight Chinese patients with chronic HBV infection. The IgM anti-preS2 (14-21) reactivity was monitored consecutively during treatment and patients were followed for more than 1 year. A close association between the presence of pretreatment IgM anti-preS2 (14-21) in serum and the capacity to respond favorably to the combined prednisone/IFN-alpha 2b therapy was detected. The IgM anti-preS2 (14-21) titers decreased during treatment with subsequent loss of detectable antibodies 8-16 weeks after the initiation of therapy. This decrease was concomitant with an alanine aminotransferase (ALT) augmentation preceding the disappearance of HBV-DNA and anti-HBe seroconversion. Long-term remission was not observed in treated patients who lacked detectable levels of pretreatment IgM anti-preS2 (14-21) in the circulation.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
939.
940.

BACKGROUND

Including forage legumes in dairy systems can help address increasing environmental/economic concerns about perennial ryegrass monoculture pastures. This work investigated the effect of substituting fresh‐cut grass with increasing quantities of fresh‐cut white clover (WC) on milk fatty acid (FA) profile and transfer efficiency of dietary linoleic (LA) and α‐linolenic (ALNA) acids to milk fat. Three groups of three crossbred dairy cows were used in a 3 × 3 crossover design. Dietary treatments were 0 g kg?1 WC + 600 g kg?1 grass, 200 g kg?1 WC + 400 g kg?1 grass, and 400 g kg?1 WC + 200 g kg?1 grass. All treatments were supplemented with 400 g kg?1 concentrates on a dry matter basis. Cows had a 19‐day adaptation period to the experimental diet before a 6‐day measurement period in individual tie stalls.

RESULTS

Increasing dietary WC did not affect dry matter intake, milk yield or milk concentrations of fat, protein or lactose. Milk polyunsaturated FA concentrations (total n‐3, total n‐6, LA and ALNA) and transfer efficiency of LA and ALNA were increased with increasing dietary WC supply.

CONCLUSION

Inclusion of WC in pastures may increase concentrations of nutritionally beneficial FA, without influencing milk yield and basic composition, but any implications on human health cannot be drawn. © 2018 The Authors. Journal of the Science of Food and Agriculture published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry.
  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