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   663篇
  免费   38篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   8篇
妇产科学   13篇
基础医学   74篇
口腔科学   12篇
临床医学   65篇
内科学   188篇
皮肤病学   15篇
神经病学   61篇
特种医学   13篇
外科学   82篇
综合类   7篇
预防医学   34篇
眼科学   17篇
药学   53篇
中国医学   5篇
肿瘤学   48篇
  2024年   2篇
  2023年   10篇
  2022年   22篇
  2021年   41篇
  2020年   17篇
  2019年   42篇
  2018年   23篇
  2017年   25篇
  2016年   14篇
  2015年   21篇
  2014年   23篇
  2013年   38篇
  2012年   63篇
  2011年   50篇
  2010年   21篇
  2009年   10篇
  2008年   31篇
  2007年   28篇
  2006年   26篇
  2005年   33篇
  2004年   25篇
  2003年   32篇
  2002年   30篇
  2001年   5篇
  2000年   4篇
  1999年   8篇
  1998年   3篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   6篇
  1988年   4篇
  1987年   3篇
  1986年   3篇
  1985年   1篇
  1984年   4篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   3篇
  1978年   2篇
  1975年   1篇
  1974年   3篇
  1972年   2篇
  1967年   2篇
排序方式: 共有702条查询结果,搜索用时 15 毫秒
61.
62.
This qualitative study explores corporations' motivations to comply with new natural health products (NHP) Regulations in Canada. Interviews were conducted with representatives from 20 Canadian NHP companies. Findings show that the rationale for compliance differs for large compared to small and medium-sized enterprises (SMEs). Large firms are motivated to comply with the regulations because of the deterrent fear of negative media coverage, social motivations, ability to comply and maintaining a competitive market advantage. In contrast, SMEs are motivated to comply due to the deterrent fear of legal prosecution and a sense of duty.  相似文献   
63.
Journal of Neuro-Oncology - Primary malignant spinal astrocytomas present rare oncological entities with limited median survival and rapid neurological deterioration. Evidence on surgical therapy,...  相似文献   
64.
Total and free triiodothyronine in human serum   总被引:4,自引:14,他引:4       下载免费PDF全文
A reliable method has been developed for the determination of total serum T3, dialyzable fraction (DFT3), and absolute concentration of free T3 (AFT3). Total T3 values (mean ± SD) were: healthy euthyroid subjects, 0.33 ± 0.07 μg per 100 ml; hyperthyroid patients, 0.71 ± 0.1 μg per 100 ml; hypothyroid, 0.10 ± 0.03 μg per 100 ml. Values (mean ± SD) for DFT3 in these groups were 0.46 ± 0.14%, 0.78 ± 0.17%, and 0.16 ± 0.08%, respectively. Calculated values for AFT3 were: 1.51 ± 0.4 mμg per 100 ml, 5.00 ± 0.6 mμg per 100 ml and 0.24 ± 0.1 mμg per 100 ml, respectively. Dilution of serum before dialysis lowered estimated DFT3 values. Enrichment of serum with labeled T3 in the range examined did not affect DFT3. However, DFT3 was increased by addition of Merthiolate to serum in concentration 1: 10,000 due to displacement of T3 from thyroxine-binding globulin to albumin. The data suggest that triiodothyronine may play a considerably more important role in normal and pathological physiology, as evidenced by kinetic analysis using these data. A metabolic role for T3 equal to that of T4 is indicated.  相似文献   
65.
Herein, we present a case of central thyrotoxicosis with well-documented serial therapeutic interventions. Thyroid-stimulating hormone (TSH)-secreting pituitary tumors represent a rare cause of hyperthyroidism. It is being diagnosed more frequently with the third-generation TSH assay. Many conditions can produce normal or elevated TSH levels in combination with elevated thyroid hormone levels. The differential diagnosis includes resistance to thyroid hormone (RTH, Refetoff's syndrome), assay interference from anti-T4/T3 and heterophile antibodies, elevated or altered binding proteins, drugs affecting peripheral metabolism, and noncompliance with thyroid replacement therapy. In contrast to RTH, our patient presented had high alpha-subunit-to-TSH molar ratio, failed TSH response to thyrotropin-releasing hormone stimulation, and a large pituitary mass. Normal or high TSH in the presence of elevated T4 or T3 is a fairly common clinical scenario with many etiologic possibilities. This TSH-producing adenoma represents an unusual initial clinical presentation, as hypogonadism appeared before features of thyrotoxicosis were appreciated. This case represents the most modern therapeutic approach to the management of this rare disease. Our patient has done well on octreotide with control of thyrotoxicosis and an additional 30% shrinkage of his tumor mass.  相似文献   
66.
67.
In this study, the industrial applications of a highly thermostable α-amylase as a desizer in the textile industry was evaluated. The cloned gene was expressed in different media (ZBM, LB, ZYBM9, and ZB) with IPTG (isopropyl β-d-1-thiogalactopyranoside) used as an inducer. Lactose was also used as an alternate inducer for the T7 promoter system in E. coli. For the large-scale production of the enzyme, different parameters were optimized. The maximum enzyme production was achieved when the volume of medium was 70% of the total volume of fermenter with a 2.0 vvm air supply and 20% dissolved oxygen at a 200 rpm agitation rate. Under all the optimized conditions, the maximum enzyme production was 22.08 U ml−1 min−1 with lactose (200 mM) as an inducer in ZBM medium. The desizing potential of the purified α-amylase enzyme was calculated with different enzyme concentrations (50–300 U ml−1) at different temperatures (50–100 °C), and pHs (4–9) with varying time intervals (30–120 min). The highest desizing activity was found when 150 U ml−1 enzyme units were utilized at 85 °C and at 6.5 pH for 1 h.

Thermostable recombinant α-amylase was produced in a large scale for the desizing of cotton cloth in the textile industry.  相似文献   
68.
69.
Mentha species are used in every day life in various food items. These species produce valuable secondary metabolites that scavenge toxic free radicals. Toxic free radicals can cause different diseases in the human body. In the present study free radical scavenging potential (1,1-diphenyl-2-picrylhydrazyl scavenging activity) in nine Mentha species were investigated to evaluate and explore new potential sources for natural antioxidants. The activity was performed after different time intervals with incubation period of 30 minutes. The methanolic extracts revealed that significantly higher activity (82%) was observed in Mentha suaveolens, followed by Mentha longifolia (79%), Mentha officinalis (76%) and Mentha piperita, Mentha pulegium, Mentha royleana (75%), respectively. Significantly same activity was observed in Mentha arvensis and Mentha spicata. Lower activity was observed in Mentha citrata (64%). The present study revealed that these species can be used as natural antioxidants.  相似文献   
70.
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