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   441篇
  免费   16篇
  国内免费   1篇
耳鼻咽喉   13篇
儿科学   4篇
妇产科学   24篇
基础医学   46篇
口腔科学   18篇
临床医学   23篇
内科学   212篇
皮肤病学   1篇
神经病学   11篇
特种医学   1篇
外科学   44篇
综合类   1篇
预防医学   12篇
眼科学   10篇
药学   27篇
肿瘤学   11篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2019年   1篇
  2018年   10篇
  2017年   4篇
  2016年   4篇
  2015年   4篇
  2014年   3篇
  2013年   13篇
  2012年   15篇
  2011年   24篇
  2010年   17篇
  2009年   14篇
  2008年   21篇
  2007年   17篇
  2006年   13篇
  2005年   15篇
  2004年   20篇
  2003年   24篇
  2002年   37篇
  2001年   20篇
  2000年   14篇
  1999年   14篇
  1998年   7篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1994年   3篇
  1993年   1篇
  1992年   11篇
  1991年   9篇
  1990年   13篇
  1989年   11篇
  1988年   5篇
  1987年   12篇
  1986年   7篇
  1985年   6篇
  1984年   9篇
  1983年   3篇
  1982年   8篇
  1981年   6篇
  1980年   5篇
  1979年   7篇
  1978年   4篇
  1977年   3篇
  1976年   3篇
  1974年   2篇
  1973年   3篇
  1970年   1篇
排序方式: 共有458条查询结果,搜索用时 31 毫秒
1.
The largest reported outbreak of type C botulism in fur production animals is described. Epidemiological investigation of 117 out of 157 (response rate, 74.5%) farms revealed that 44,130 animals died or were euthanized, while 8,033 animals with milder symptoms recovered. The overall death rate in all animals at risk was 21.7%. The death rates were significantly higher in blue and shadow foxes (24.2 and 27.8%, respectively) than in silver and blue silver foxes and minks (below 4%). All minks had been immunized against botulinum toxin type C. Deaths were associated with feed manufactured by a local processor, 83 of whose customer farms (70.9%) reported dead or sick animals. Five feedlots out of 19 delivered to the farms on the day preceding the onset of the outbreak (day 2) were associated with a death rate higher than 40%. These feedlots consisted of fresh feed processed on day 2 and feed processed 1 day earlier (day 1). In laboratory analysis, the day 2 feed contained botulinum toxin type C (>600 minimum lethal doses/g), while the day 1 feed did not contain toxin. Toxin was not detected in feed raw-material samples. Clostridium botulinum type C was detected by PCR in some feed components and in feed. However, as the feed temperature was continuously 8 degrees C or below and the pH was continuously 5.6 or below according to the manufacturer, it seems unlikely that spore germination and toxin formation occurred during overnight storage. Hence, the events leading to toxin formation were not determined.  相似文献   
2.
BACKGROUND: Inactivating mutations of the FSH receptor (FSHR) are a rare cause of hypergonadotrophic hypogonadism in women. Only one patient with primary amenorrhoea due to an FSHR gene mutation has been reported outside of Finland, where the prevalence of Ala189Val mutations is particularly high. METHODS AND RESULTS: Here, we describe the clinical, molecular genetic and functional characteristics associated with a novel inactivating mutation in exon 10 of the FSHR gene identified in a patient who presented with primary amenorrhoea at 17 years of age. The C to G transversion found at nucleotide 1043 causes a Pro348Arg substitution in the extracellular region of the FSHR and results in a mutant FSHR that is completely inactive in functional studies and that does not bind FSH. The proband exhibits apparent homozygosity for this recessive mutation. Her father is heterozygous for the mutation while analysis of exon 10 of the FSHR gene from her mother revealed only wild-type sequence. Chromosome painting was used to exclude deletions or rearrangements of 2p, and microsatellite markers did not show paternal uniparental isodisomy for this region. These findings suggest that the proband is hemizygous, with an inherited or de-novo microdeletion, or alternatively a de-novo gene conversion, of the accompanying FSHR allele. CONCLUSIONS: This case confirms the importance of the FSHR in female pubertal development and reproduction, and supports a relationship between phenotype and function for FSHR mutations.  相似文献   
3.
As President of the International Society of Andrology, it gives me great pleasure to congratulate the Asian Society of Andrology for its initiative in founding the Asian Journal of Andrology. In doing so, I also send my best wishes for the success of this important journal in spreading the knowledge of andrology throughout the most populous continent in the world. This new journal appears at a very timely moment, at the turn of the millennium and at a time when andrology is receiving the recognition amongst medical specialities that it deserves. In conclusion, I would like to call on all Asian andrologists to support their journal and to work to improve the reproductive health of men.  相似文献   
4.
5.
Pretreatment of rats with hormones that suppress testosterone levels and sperm production enhances the recovery of spermatogenesis from stem cells after a cytotoxic insult. It is not known whether the enhanced recovery results from an increase in the numbers of surviving stem cells or whether their ability to differentiate is enhanced. In this study, untreated rats and rats pretreated with testosterone plus estradiol-17beta (T + E) were irradiated with 3.5 or 6 Gy, and the recovery of spermatogenesis from surviving stem cells was assessed at 6, 10, and 20 weeks after irradiation. T + E pretreatment did not significantly affect the numbers of A spermatogonia remaining in the tubules at 6 weeks after irradiation. In rats that were given irradiation alone, spermatogenesis steadily declined after 6 weeks because the stem cells lost their ability to differentiate. However, when rats were treated with T + E before irradiation, this decline was prevented, and in fact, at least at the lower dose of radiation, there was a progressive recovery of spermatogenesis. Given the similar spermatogonial counts at 6 weeks after irradiation in the irradiated-only and T + E-treated, irradiated rats, the hormone treatment appears not to protect stem cells from being killed by the cytotoxic agent. Rather, the later enhancement of spermatogenic recovery results from prevention of an injury-induced change in spermatogonia or in their environment, which would have otherwise resulted in failure of spermatogonial differentiation.  相似文献   
6.
Objective. To evaluate the psychometric properties (criterion validity, construct validity, sensitivity, and specificity) of a single-item question screening for dental anxiety in a Finnish adult population. Material and methods. A total of 823 subjects, ranging in age from 18 to 87 years, answered a questionnaire comprising sections assessing the respondents’ demographic profile and dental attendance patterns. A single dental anxiety question and the Modified Dental Anxiety Scale (MDAS) were included. The final response rate was 85%. Results. Eight percent of the sample was highly dentally anxious using the MDAS cut-off point of 19 or above. Twelve percent of the respondents rated themselves as “very scared” on the single-item question. The percentage agreement between the single-item question and the MDAS was 93; the Kappa coefficient was 0.63. Specificity of the single question was 0.95 while sensitivity was 0.80 using the MDAS dichotomous classification. The single-item question related to age (p<0.001), gender (p<0.001), and dental attendance (p<0.001), as predicted. Conclusions. The single question has good validity, specificity, and sensitivity and may be used with confidence to assess dental fear in such situations as national health surveys or in routine dental practice where a multi-item dental anxiety questionnaire is not feasible.  相似文献   
7.
8.
Increased carotid atherosclerosis in andropausal middle-aged men   总被引:2,自引:0,他引:2  
OBJECTIVES: This study examined the association between carotid artery intima-media thickness (IMT), serum sex hormone levels, and andropausal symptoms in middle-aged men. BACKGROUND: Male sex hormones may play a dual role in the pathogenesis of atherosclerosis in men by carrying both proatherogenic and atheroprotective effects. METHODS: We studied 239 40- to 70-year-old men (mean +/- SD: 57 +/- 8 years) who participated in the Turku Aging Male Study and underwent serum lipid and sex hormone measurements. Ninety-nine men (age 58 +/- 7 years) were considered andropausal (i.e., serum testosterone <9.8 nmol/l or luteinizing hormone [LH] >6.0 U/l and testosterone in the normal range), and in both situations, they had subjective symptoms of andropause (a high symptom score in questionnaire). Three were excluded because of diabetes. The rest of the men (age 57 +/- 8 years) served as controls. Carotid IMT was determined using high-resolution B-mode ultrasound, and serum testosterone, estradiol (E2), LH, and sex hormone-binding globulin were measured using standard immunoassays. RESULTS: Andropausal men had a higher maximal IMT compared with controls in the common carotid (1.08 +/- 0.34 vs. 1.00 +/- 0.23, p < 0.05) and in the carotid bulb (1.44 +/- 0.48 vs. 1.27 +/- 0.35, p = 0.003). Common carotid IMT correlated inversely with serum testosterone (p = 0.003) and directly with LH (p = 0.006) in multivariate models adjusted for age, total cholesterol, body mass index, blood pressure, and smoking. CONCLUSIONS: Middle-aged men with symptoms of andropause, together with absolute or compensated (as reflected by high normal to elevated LH) testosterone deficiency, show increased carotid IMT. These data suggest that normal testosterone levels may offer protection against the development of atherosclerosis in middle-aged men.  相似文献   
9.
10.
Suppression of intratesticular testosterone (ITT) levels is required for spermatogenic recovery in rats after irradiation, but maintenance of peripheral testosterone (T) levels is important for many male functions. Considering the preservation of peripheral T while suppressing ITT, we tested the effects of a combination of a progestin, medroxyprogesterone acetate (MPA), plus T on spermatogenic recovery after irradiation, and compared its effects to those of T alone or T combined with estradiol (E2). Rats were given testicular irradiation (6 Gy) and treated during wk 3-7 after irradiation with MPA + T, or the individual steroids with or without GnRH antagonist (GnRH-ant), or GnRH-ant alone, or T + E2. Whereas GnRH-ant alone stimulated differentiation in 55% of tubules 13 wk after irradiation compared with 0% in irradiated-only rats, the addition of MPA reduced the percentage of tubules showing differentiation to 18%. However, T or MPA alone or the combination of the two induced germ cell differentiation in only 2-4% of tubules. In contrast, E2 stimulated differentiation in 88% of tubules, and T combined with E2 still resulted in differentiation in 30% of tubules. Although both MPA and E2 suppressed ITT levels to approximately 2% of control (2 ng/g testis), MPA was a less effective stimulator of spermatogenic recovery than E2 or GnRH-ant alone. MPA's function as a weak androgen was likely responsible for inhibiting spermatogenic recovery, as was the case for all other tested androgens. Thus, for clinical protection or restoration of spermatogenesis after radiation or chemotherapy by suppressing T production, MPA, at least in the doses used in the present study, is suboptimal. The combination of an estrogen with T appears to be most effective for stimulating such recovery.  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