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   2029篇
  免费   152篇
  国内免费   9篇
耳鼻咽喉   7篇
儿科学   215篇
妇产科学   149篇
基础医学   192篇
口腔科学   18篇
临床医学   220篇
内科学   441篇
皮肤病学   36篇
神经病学   104篇
特种医学   339篇
外科学   187篇
综合类   31篇
一般理论   7篇
预防医学   89篇
眼科学   19篇
药学   81篇
肿瘤学   55篇
  2021年   35篇
  2020年   20篇
  2019年   31篇
  2018年   34篇
  2017年   29篇
  2016年   28篇
  2015年   28篇
  2014年   50篇
  2013年   53篇
  2012年   96篇
  2011年   97篇
  2010年   54篇
  2009年   37篇
  2008年   94篇
  2007年   93篇
  2006年   92篇
  2005年   71篇
  2004年   81篇
  2003年   77篇
  2002年   51篇
  2001年   54篇
  2000年   42篇
  1999年   60篇
  1998年   46篇
  1997年   43篇
  1996年   37篇
  1995年   40篇
  1994年   23篇
  1993年   26篇
  1992年   41篇
  1991年   31篇
  1990年   37篇
  1989年   40篇
  1988年   43篇
  1987年   44篇
  1986年   41篇
  1985年   40篇
  1984年   36篇
  1983年   36篇
  1982年   36篇
  1981年   25篇
  1980年   29篇
  1979年   15篇
  1978年   23篇
  1977年   24篇
  1976年   24篇
  1975年   14篇
  1974年   11篇
  1973年   9篇
  1971年   7篇
排序方式: 共有2190条查询结果,搜索用时 15 毫秒
21.
A flavivirus microarray was developed for detection and identification of yellow fever (YF), West Nile, Japanese encephalitis (JE), and the dengue 1-4 viruses, which are causing severe human disease all over the world. The microarray was based on 500-nucleotide probe fragments from five different parts of the seven viral genomes. A low-stringent amplification method targeting the corresponding regions of the viral genomic RNA was developed and combined with hybridization to the microarray for detection and identification. For distinction of the generated virus-specific fluorescence-patterns a fitting analysis procedure was adapted. The method was verified as functional for all seven flaviviruses and the strategy for the amplification, combined with the long probes, provided a high tolerance for smaller genetic variability, most suitable for these rapidly changing RNA viruses. A potentially high detection and identification capacity was proven on diverged strains of West Nile and dengue viruses. The lower limit for detection was equivalent, or better, when compared to routinely used RT-PCR methods. The performance of the method was verified on human patient samples containing dengue viruses, or normal human serum spiked with YF or JE viruses. The results demonstrated the ability of the flavivirus microarray to screen simultaneously a sample for several viruses in parallel, in combination with a good lower limit of detection.  相似文献   
22.
23.
24.
We studied anorectal sensory and motor function in 14 diabetics with fecal incontinence and compared the results with those in 13 continent diabetics, 31 nondiabetics with fecal incontinence, and 11 continent nondiabetics. The threshold volume at which diabetic patients with fecal incontinence experienced rectal sensation was higher (25.0 +/- 3.4 ml [mean +/- S.E.M.]) than that in continent diabetics (13.0 +/- 2.4 ml) or nondiabetics with or without incontinence (14.5 +/- 1.5 and 12.5 +/- 1.8 ml, respectively; P less than 0.02). Biofeedback conditioning in 11 incontinent diabetics led to normal sensory thresholds in six of seven patients with pretreatment thresholds above 20 ml; five of these six became continent. Biofeedback also improved external-sphincter function in nine diabetics, eight of whom became continent. Overall, 8 of 11 diabetics had a reduction in fecal soiling after biofeedback therapy. We conclude that fecal incontinence in diabetics may be caused by decreased rectal sensation or impaired function of the external sphincter or both, and that these abnormalities can often be improved by biofeedback therapy with resultant reestablishment of bowel control.  相似文献   
25.
26.
27.
Fifty women with polycystic ovaries took part in a prospective randomized study. All women required treatment by in-vitro fertilization (IVF) for reasons other than anovulation. They had all previously undergone ovarian stimulation with gonadotrophin therapy which had failed to result in pregnancy or had been abandoned due to high risk of developing ovarian hyperstimulation syndrome (OHSS). Twenty-five women were treated by long-term pituitary desensitization followed by gonadotrophin therapy, oocyte retrieval and embryo transfer (group 1). Twenty-five women underwent laparoscopic ovarian electrocautery after pituitary desensitization followed by gonadotrophin therapy, oocyte retrieval and embryo transfer (group 2). A significantly higher number of women in group 1 had to have the treatment cycle abandoned due to impending or actual OHSS, determined by endocrine and clinical findings. In addition, the development of moderate or severe OHSS in completed cycles was higher in group 1. The pregnancy rate and miscarriage rates in the two treatment groups were similar. The authors propose that laparoscopic ovarian electrocautery is a potentially useful treatment for women who have previously had an IVF treatment cycle cancelled due to risk of OHSS or who have suffered OHSS in a previous treatment cycle.   相似文献   
28.
29.
 Vitamin D counters the phosphaturic action of parathyroid hormone (PTH) in rats in vivo. The present study was undertaken to examine this interaction using monolayers of Opossum kidney (OK) cells. 32P uptake, cAMP generation, PTH/PTHrP receptor mRNA expression and intracellular Ca2+ [Ca2+]i were measured in (1) control cells, (2) cells exposed to PTH, (3) cells pretreated with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and (4) 1,25(OH)2D3-pretreated cells exposed to PTH. 32P uptakes were in (1) 5.00±0.20 (mean ±SE), in (2) 2.30±0.14 (P<0.001 versus group 1), in (3) 4.80±0.24 (P NS versus group 1) and in (4) 3.70±0.20 (P<0.001 versus group 2) nmol Pi/(mg·prot 10 mm). cAMP levels were in (1) 10±3, in (2) 210±8, in (3) 12±4, and in (4) 122±12 pmol cAMP/mg protein (P<0.001 versus group 2). PTH/PTHrP receptor mRNA expression was in relative units: (1) 100±0, (2) 99.5±6.2, (3) 68.7±2.6 (P<0.001 versus group 1), and (4) 34.8±3.3 (P<0.001 versus group 1). In groups 2 and 4 PTH induced equal transient increments in [Ca2+]i. These experiments demonstrate that the effect of vitamin D on phosphate transport is associated with a commensurate diminution in PTH/PTHrP receptor gene expression and PTH-induced cAMP formation but not with Ca2+ transients. Vitamin D per se does not affect 32P uptake or cAMP generation while it slightly decreased PTH/PTHrP receptor gene expression. These observations demonstrate that: (1) 1.25(OH)2D3 directly antagonizes the effects of PTH on 32P uptake in OK cells, (2) this effect is mediated via inhibition of PTH-induced activation of AC/cAMP system, (3) the diminution in PTH-induced cAMP formation may stem at least in part from a decrease in the expression of PTH/PTHrP receptor mRNA. Received: 2 December 1997 / Received after revision: 19 January 1998 / Accepted: 28 January 1998  相似文献   
30.
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