全文获取类型
收费全文 | 3755篇 |
免费 | 256篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 191篇 |
妇产科学 | 86篇 |
基础医学 | 594篇 |
口腔科学 | 86篇 |
临床医学 | 346篇 |
内科学 | 737篇 |
皮肤病学 | 91篇 |
神经病学 | 349篇 |
特种医学 | 478篇 |
外科学 | 317篇 |
综合类 | 40篇 |
一般理论 | 1篇 |
预防医学 | 192篇 |
眼科学 | 21篇 |
药学 | 207篇 |
1篇 | |
中国医学 | 4篇 |
肿瘤学 | 271篇 |
出版年
2021年 | 45篇 |
2020年 | 22篇 |
2019年 | 53篇 |
2018年 | 60篇 |
2017年 | 46篇 |
2016年 | 49篇 |
2015年 | 69篇 |
2014年 | 82篇 |
2013年 | 115篇 |
2012年 | 109篇 |
2011年 | 100篇 |
2010年 | 106篇 |
2009年 | 129篇 |
2008年 | 106篇 |
2007年 | 149篇 |
2006年 | 124篇 |
2005年 | 123篇 |
2004年 | 93篇 |
2003年 | 125篇 |
2002年 | 104篇 |
2001年 | 106篇 |
2000年 | 100篇 |
1999年 | 91篇 |
1998年 | 128篇 |
1997年 | 131篇 |
1996年 | 134篇 |
1995年 | 92篇 |
1994年 | 94篇 |
1993年 | 117篇 |
1992年 | 54篇 |
1991年 | 67篇 |
1990年 | 72篇 |
1989年 | 88篇 |
1988年 | 69篇 |
1987年 | 61篇 |
1986年 | 60篇 |
1985年 | 76篇 |
1984年 | 40篇 |
1983年 | 41篇 |
1982年 | 36篇 |
1981年 | 48篇 |
1980年 | 34篇 |
1979年 | 39篇 |
1978年 | 31篇 |
1977年 | 42篇 |
1976年 | 29篇 |
1971年 | 22篇 |
1929年 | 20篇 |
1926年 | 34篇 |
1925年 | 21篇 |
排序方式: 共有4036条查询结果,搜索用时 31 毫秒
1.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight. 相似文献
2.
ME BURGE AM JOSHUA CM McNEIL R HUI MJ BOYER R ABRAHAM 《Asia-Pacific Journal of Clinical Oncology》2005,1(1):47-52
Background: Pemetrexed and cisplatin have recently been shown to significantly improve survival compared with cisplatin alone. However, there are only limited data reflecting teaching hospital experience outside a clinical trial. Pemetrexed has only been available in Australia on a restricted basis since 2002. We reviewed our experience of patients treated on the Australian ‘Special Access Scheme’ at three major thoracic oncology units. Methods: Charts were reviewed for all patients enrolled on the scheme. Data was extracted on age, World Health Organization (WHO) performance status, histology, prior therapy, time from diagnosis to starting pemetrexed, chemotherapy (pemetrexed alone or with a platinum), cycle number, response rate, actuarial progression‐free and overall survival. Doses were cisplatin 75 mg/m2 or carboplatin AUC = 5 and pemetrexed 500 mg/m2 every 21 days. Results: 52 patients (32 male and 20 female) were reviewed. Median age was 58 years and 88% were WHO 0–1. Histology included 54% epithelial, 17% biphasic (epithelial and sarcomatoid) and 21% undefined. The median time from diagnosis to administration of pemetrexed was 145 days. Sixty‐five percent had minimal surgical intervention with video assisted thoracoscopy, pleurodesis and biopsy, while 19% had received prior palliative radiation. Seventy‐one percent were chemotherapy naïve, the remaining 29% having received previous platinum and/or gemcitabine regimens. Twenty‐three percent had pemetrexed alone, 35% in combination with carboplatin and 42% with cisplatin. The median number of cycles was 4 (range 1–13). The response rate was 33%. No toxicity was observed in 20% grade 3–4 toxicity in 10% (majority nausea/vomiting). The median progression‐free and overall survival times from starting pemetrexed were 184 days and 298 days, respectively. Conclusions: Pemetrexed‐based regimens are safe and effective in a community setting in malignant mesothelioma. 相似文献
3.
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
4.
G Fitze J Cramer A Serra M Schreiber D Roesner H K Schackert 《Zeitschrift für Kinderchirurgie》2003,13(3):152-157
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
5.
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
6.
A F Cacciapuoti D Loebenberg E L Moss F W Menzel J A Rudeen L R Naples C L Cramer R S Hare A K Mallams G H Miller 《The Journal of antibiotics》1990,43(9):1131-1136
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
7.
8.
CM Reid M. Nelson P. Beckinsale P. Ryan LMH Wing LJ Beilin MA Brown GLR Jennings CI Johnston J. Marley JJ McNeil TO Morgan J. Shaw ID Steven MJ West 《Clinical and experimental pharmacology & physiology》1997,24(5):370-373
1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial. 相似文献
9.
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
10.