首页 | 官方网站   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   2423篇
  免费   170篇
  国内免费   3篇
医药卫生   2596篇
  2021年   34篇
  2019年   41篇
  2018年   41篇
  2017年   30篇
  2016年   29篇
  2015年   44篇
  2014年   60篇
  2013年   70篇
  2012年   103篇
  2011年   91篇
  2010年   76篇
  2009年   56篇
  2008年   91篇
  2007年   117篇
  2006年   90篇
  2005年   95篇
  2004年   79篇
  2003年   102篇
  2002年   85篇
  2001年   87篇
  2000年   79篇
  1999年   61篇
  1998年   34篇
  1997年   27篇
  1996年   32篇
  1995年   20篇
  1994年   23篇
  1993年   28篇
  1992年   40篇
  1991年   50篇
  1990年   56篇
  1989年   46篇
  1988年   33篇
  1987年   39篇
  1986年   29篇
  1985年   48篇
  1984年   23篇
  1983年   28篇
  1982年   18篇
  1979年   31篇
  1978年   23篇
  1977年   21篇
  1974年   15篇
  1973年   20篇
  1971年   22篇
  1967年   16篇
  1929年   20篇
  1928年   19篇
  1926年   34篇
  1925年   21篇
排序方式: 共有2596条查询结果,搜索用时 62 毫秒
1.
2.
Cramer  J.  David  S.  Wich  M. 《Trauma und Berufskrankheit》2007,9(2):S220-S222
Trauma und Berufskrankheit - Nur 0,4–1% aller Frakturen betreffen die Skapula, die meisten davon können erfolgreich konservativ funktionell behandelt werden. Zur Identifikation der...  相似文献   
3.
Hirschsprung disease (HSCR) is considered a model for a complex inheritance disorder. Several genes, including the major HSCR-susceptibility RET proto-oncogene, play an aetiological role in the development of HSCR. Genetic linkage analysis in familial HSCR with both long- and short-segment phenotypes has demonstrated a tight linkage to the RET locus, while the phenotype within a HSCR family is characterised by an incomplete penetrance or a variable extension of the aganglionosis. Therefore, additional genetic alterations of RET are postulated in the aetiology or modification of the HSCR phenotype. In this study, the coding region of all 21 exons of the RET proto-oncogene, including the flanking intronic sequences, were investigated by direct DNA sequencing in a HSCR population. We genotyped the c.135 G/A polymorphism and resolved haplotypes comprising the mutation locus and the c.135 G/A polymorphism. Twenty different mutations were detected in 18 of 76 HSCR patients. In ten families the mutations were inherited from the parents, while only four patients had a positive family history for the disease. Moreover, in all ten families an incomplete penetrance of the HSCR phenotype was observed. We have investigated the effect of the non-mutated wild-type allele as well as the c.135 G/A polymorphism on the phenotype within the HSCR families. Our findings support the notion that both RET alleles are involved in the pathogenesis of a subgroup of HSCR patients in a dose-dependent fashion. Additionally, we have shown a modifying effect of the c.135 G/A polymorphism on the HSCR phenotype within HSCR families.  相似文献   
4.
Reproductive Function in Epilepsy   总被引:10,自引:10,他引:0  
Summary: : The hypothalamic-pituitary-gonadal axis is a complex system within which both positive and negative feedback occur among its elements and higher brain systems. The occurrence of seizures and changes in the secretion of pituitary hormones can affect the feedback loop. Both seizures and antiepileptic drugs can affect the hypothalamic-pituitary-gonadal axis of males and females and cause changes in hormones and sexuality. Reproductive dysfunction has a social impact because of reduced fertility. Once conception occurs, live birth rates are not diminished. Prospective studies of men and women with epilepsy are needed.  相似文献   
5.
A series of tylosins and acyl derivatives of 23-O-demycinosyltylosin (DMT) were initially tested for in vitro antibacterial activity and serum levels in squirrel monkeys (po) and mice (iv). Overall, the DMT compounds were more active in vitro than the tylosins. Two tetraacylated DMTs, Sch 37644 and Sch 38646, were selected from the initial studies for further evaluation and compared to erythromycin and A-56268 (6-O-methyl erythromycin). Sch 37644 and Sch 38646 were 2 to 8-fold less potent in vitro against Gram-positive bacteria than erythromycin and A-56268. In squirrel monkeys, Sch 37644 (AUC, 19.7 micrograms.hour ml) and A-56268 (21.6 micrograms.hour/ml) had similar serum levels following po administration of 20 mg/kg, while Sch 38646 (11.8 micrograms.hour/ml) and erythromycin (1.5 micrograms.hour/ml) had lower levels. In mice administered 200 mg/kg orally, Sch 37644 (AUC, 19.4 micrograms.hour/ml) and Sch 38646 (15.4 micrograms.hour/ml) had higher serum levels than erythromycin (5.7 micrograms.hour/ml). A-56268 was the most active po macrolide in mouse protection studies (PD50S) against Staphylococci and Streptococci, while Sch 37644 and Sch 38646 were similar to erythromycin.  相似文献   
6.
7.
Infertility in women and moderate alcohol use.   总被引:16,自引:2,他引:14       下载免费PDF全文
OBJECTIVE. The purpose of this study was to investigate the relationship between moderate alcohol intake and fertility. METHODS. Interviews were conducted with 3833 women who recently gave birth and 1050 women from seven infertility clinics. The case subjects were categorized based on the infertility specialist's assignment of the most likely cause of infertility: ovulatory factor, tubal disease, cervical factor, endometriosis, or idiopathy. Separate logistic regression models were used to assess the relationship between alcohol use and each type of infertility, adjusted for age, infertility center, cigarette smoking, caffeine use, number of sexual partners, use of an intrauterine device (for tubal disease), and body mass index and exercise (for ovulatory factor). RESULTS. We found an increase in infertility, due to ovulatory factor or endometriosis, with alcohol use. The odds ratio for ovulatory factor was 1.3 (95% confidence interval [CI] = 1.0, 1.7) for moderate drinkers and 1.6 (95% CI = 1.1, 2.3) for heavier drinkers, compared with nondrinkers. The risk of endometriosis was roughly 50% higher in case subjects with any alcohol intake than in control subjects (OR = 1.6, 95% CI = 1.1, 2.3, at moderate levels; OR = 1.5, 95% CI = 0.8, 2.7, at heavier levels). CONCLUSIONS. Moderate alcohol use may contribute to the risk of specific types of infertility.  相似文献   
8.
ABSTRACT. The phonological abilities of two groups of 4–9-year-old intellectually impaired Cantonese-speaking children are described. Children with Down's syndrome did not differ from matched non-Down's syndrome controls in terms of a lexical comprehension measure, the size of their phoneme repertoires, the range of sounds affected by articulatory imprecision, or the number of consonants, vowels or tones produced in error. However, the types of errors made by the Down's syndrome children were different from those made by the control subjects. Cantonese-speaking children with Downs syndrome, as compared with controls, made a greater number of inconsistent errors, were more likely to produce non-developmental errors and were better in imitation than in spontaneous production. Despite extensive differences between the phonological structures of Cantonese and English, children with Downs syndrome acquiring these languages show the same characteristic pattern of speech errors. One unexpected finding was that the control group of non-Down's syndrome children failed to present with delayed phonological development typically reported for their English-speaking counterparts. The argument made is that cross-linguistic studies of intellectually impaired children's language acquisition provide evidence concerning language-specific characteristics of impairment, as opposed to those characteristics that, remaining constant across languages, are an integral part of the disorder. The results reported here support the hypothesis that the speech disorder typically associated with Down's syndrome arises from impaired phonological planning, i.e. a cognitive linguistic deficit.  相似文献   
9.
10.
OBJECTIVE: We sought to determine whether the use of talc in genital hygiene increases the risk for epithelial ovarian cancer. METHODS: We interviewed 235 white women diagnosed with epithelial ovarian cancer between 1984-1987 at ten Boston metropolitan area hospitals and 239 population-based controls of similar race, age, and residence. RESULTS: Overall, 49% of cases and 39% of controls reported exposure to talc, via direct application to the perineum or to undergarments, sanitary napkins, or diaphragms, which yielded a 1.5 odds ratio (OR) for ovarian cancer (95% confidence interval [CI] 1.0-2.1). Among women with perineal exposure to talc, the risk was significantly elevated in the subgroups of women who applied it: 1) directly as a body powder (OR 1.7, 95% CI 1.1-2.7), 2) on a daily basis (OR 1.8, 95% CI 1.1-3.0), and 3) for more than 10 years (OR 1.6, 95% CI 1.0-2.7). The greatest ovarian cancer risk associated with perineal talc use was observed in the subgroup of women estimated to have made more than 10,000 applications during years when they were ovulating and had an intact genital tract (OR 2.8, 95% CI 1.4-5.4); however, this exposure was found in only 14% of the women with ovarian cancer. CONCLUSIONS: These data support the concept that a life-time pattern of perineal talc use may increase the risk for epithelial ovarian cancer but is unlikely to be the etiology for the majority of epithelial ovarian cancers.  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-23

京公网安备 11010802026262号