全文获取类型
收费全文 | 14248篇 |
免费 | 676篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 219篇 |
儿科学 | 440篇 |
妇产科学 | 616篇 |
基础医学 | 1837篇 |
口腔科学 | 556篇 |
临床医学 | 1095篇 |
内科学 | 3081篇 |
皮肤病学 | 370篇 |
神经病学 | 857篇 |
特种医学 | 479篇 |
外国民族医学 | 3篇 |
外科学 | 2275篇 |
综合类 | 249篇 |
一般理论 | 5篇 |
预防医学 | 861篇 |
眼科学 | 246篇 |
药学 | 1059篇 |
1篇 | |
中国医学 | 113篇 |
肿瘤学 | 622篇 |
出版年
2023年 | 143篇 |
2022年 | 269篇 |
2021年 | 489篇 |
2020年 | 299篇 |
2019年 | 387篇 |
2018年 | 559篇 |
2017年 | 339篇 |
2016年 | 396篇 |
2015年 | 406篇 |
2014年 | 544篇 |
2013年 | 748篇 |
2012年 | 940篇 |
2011年 | 980篇 |
2010年 | 595篇 |
2009年 | 412篇 |
2008年 | 734篇 |
2007年 | 742篇 |
2006年 | 772篇 |
2005年 | 633篇 |
2004年 | 639篇 |
2003年 | 553篇 |
2002年 | 542篇 |
2001年 | 344篇 |
2000年 | 375篇 |
1999年 | 312篇 |
1998年 | 91篇 |
1997年 | 69篇 |
1996年 | 95篇 |
1995年 | 71篇 |
1994年 | 56篇 |
1993年 | 57篇 |
1992年 | 83篇 |
1991年 | 86篇 |
1990年 | 63篇 |
1989年 | 87篇 |
1988年 | 54篇 |
1987年 | 50篇 |
1986年 | 55篇 |
1985年 | 46篇 |
1984年 | 49篇 |
1983年 | 34篇 |
1982年 | 34篇 |
1981年 | 39篇 |
1980年 | 37篇 |
1979年 | 38篇 |
1978年 | 34篇 |
1975年 | 33篇 |
1974年 | 40篇 |
1973年 | 37篇 |
1967年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Rainer Burghard Ralf Pallacks Nader Gordjani Jekabs U. Leititis Bernhard J. Hackelöer Matthias Brandis 《Pediatric nephrology (Berlin, Germany)》1987,1(4):574-580
Protein content and protein composition were studied in amniotic fluid obtained from 171 healthy pregnant women between the 16th and 38th week of gestation, using microgradient gel electrophoresis to separate proteins according to their molecular size into albumin (68 KD), proteins of low molecular weight (LMW proteins, <68 KD), and proteins of high molecular weight (HMW proteins, >68 KD). Additionally -1-microglobulin (-1-MG, 33 KD) and -2-microglobulin (-2-MG, 11,8 KD) were analysed as micromolecular marker proteins. Concentrations of LMW proteins were 0.15–0.22 g/l, of -1-MG 28.4–34.5 mg/l, and of -2-MG 7.2–11.6 mg/l during the second trimester of gestation, and thereafter decreased progressively to 0.03 g/l, 14.1 mg/l and 2.4 mg/l respectively near term. The same developmental trends were confirmed by calculating the protein/creatinine ratios in amniotic fluid. The concentrations of LMW proteins found in the first postnatal urine of 73 healthy infants born prematurely or at term were similar to those in amniotic fluid of corresponding fetal age. Concentrations of albumin and HMW proteins in postnatal urine were about 5% and 15% respectively when compared with amniotic fluid concentrations. No strong correlation existed between gestational age and either of the analysed proteins which would allow accurate assessment of fetal maturation by protein analysis in amniotic fluid. It is concluded that fetal urinary excretion is the major determinant of the microprotein content of amniotic fluid. Microproteins seem to reflect an increasing tubular reabsorption capacity, which accelerates rapidly after the second trimester of gestation. 相似文献
62.
63.
This study considers false results which may arise due to problems in the preparation or examination of specimens for darkground microscopy of subgingival plaque. Subgingival plaque samples obtained with a sterile curette were placed in 0.1-0.3 ml sterile full or 1/4 strength Ringer's solution: 0.85% saline, 1% gelatin in 0.85% saline, formal saline or pyrogen-free water for injection. Test slides were prepared from the original dispersion, and control slides from the corresponding sterile solution. Optimal dispersion solution, syringe dispersion frequency and the effect on motility of delay in processing samples were tested. Slides were also prepared from dispersions of 11 representative subgingival "periodontopathic" organisms. Problems in sampling included variability in counts between sites with comparable pocket depths, contamination of the sample and reduction of the sample volume after scaling. Problems in dispersion included contamination, uneven distribution of the different morphotypes and destruction of delicate organisms. Problems in slide preparation included slide contamination, limitation in the number of samples that can be assessed by one examiner at a given time without loss of activity of motile cells, and preparation of a cell monolayer. Problems in identification and counting included confusion of Brownian movements with motility, coccoid particles with cocci, spirochetes with campylobacter, flagella with flagella-like structures, size of cocci, counting of fragmented spirochetes and non-motile flagellated organisms and motile cells, and also bias in counting. Problems in morphotype grouping included the observation that many (10 of the 11 representative) periodontitis-related organisms were in the non-motile groups and not all cells of the motile species (Campylobacter, Capnocytophaga) showed motility. The results indicate that each stage of subgingival plaque darkground microscopy, sampling, dispersion, slide preparation, counting, morphotype grouping and interpretation may lead to false results if not representative or reproducible. Procedures are suggested for the minimisation of problems in the preparation and examination of subgingival plaque specimens for darkground microscopy. 相似文献
64.
Mai-Lei Woo Kinshella Shazmeen Omar Kerri Scherbinsky Marianne Vidler Laura A. Magee Peter von Dadelszen Sophie E. Moore Rajavel Elango The PRECISE Conceptual Framework Working Group 《Nutrients》2021,13(2)
The placenta is a vital, multi-functional organ that acts as an interface between maternal and fetal circulation during pregnancy. Nutritional deficiencies during pregnancy alter placental development and function, leading to adverse pregnancy outcomes, such as pre-eclampsia, infants with small for gestational age and low birthweight, preterm birth, stillbirths and maternal mortality. Maternal nutritional supplementation may help to mitigate the risks, but the evidence base is difficult to navigate. The primary purpose of this umbrella review is to map the evidence on the effects of maternal nutritional supplements and dietary interventions on pregnancy outcomes related to placental disorders and maternal mortality. A systematic search was performed on seven electronic databases, the PROSPERO register and references lists of identified papers. The results were screened in a three-stage process based on title, abstract and full-text by two independent reviewers. Randomized controlled trial meta-analyses on the efficacy of maternal nutritional supplements or dietary interventions were included. There were 91 meta-analyses included, covering 23 types of supplements and three types of dietary interventions. We found evidence that supports supplementary vitamin D and/or calcium, omega-3, multiple micronutrients, lipid-based nutrients, and balanced protein energy in reducing the risks of adverse maternal and fetal health outcomes. However, these findings are limited by poor quality of evidence. Nutrient combinations show promise and support a paradigm shift to maternal dietary balance, rather than single micronutrient deficiencies, to improve maternal and fetal health. The review is registered at PROSPERO (CRD42020160887). 相似文献
65.
Špacírová Zuzana Epstein David Espín Jaime 《The European journal of health economics》2022,23(9):1563-1575
The European Journal of Health Economics - Economic evaluation of health technologies requires healthcare resources, procedures and services to be valued at their opportunity cost. In practice,... 相似文献
66.
新疆喀什市细菌性阴道病(BV)的调查 总被引:5,自引:0,他引:5
目的:了解细菌性阴道病(BV)在喀什市育齿妇女普查人群中的患病情况。方法:对822名妇科普查的妇女按Amsel等对细菌性阴道病(BV)诊断的4项标准进行检测及宫颈防癌涂片筛查。结果:细菌性阴道病(BV)在普查妇女中患病率为19.59%(161/822)。患者无主诉、无明显白带增多等症状占68.32%(110/161)。不孕症14例占8.69%(14/161),合并滴虫、霉菌性阴道炎出现阴道充血、瘙7痒等症状来就诊检查者51例。占40.37%(65/161),有阴道上尾丝环史104例。结论:建议有条件的医院及计划生育指导所,在妇科生殖健康服务时,应将查BGV列为常规门诊检测项目。 相似文献
67.
International Urology and Nephrology - To evaluate the effect of masturbation on the spontaneous expulsion of distal ureteral stones 5–10 mm in size. A total of 128 men with distal... 相似文献
68.
Abdelaal M. Elkamshoushi Noha M. Badae Mohamed G. Kabary Shaimaa I. Omar 《Andrologia》2021,53(1):e13833
Avanafil is a highly selective and potent oral phosphodiesterase type 5 inhibitor. However, its impact on the soluble markers of endothelial function has not been investigated yet. This study was conducted to assess the effect of daily avanafil on the endothelial markers' serum level and erectile function in patients with erectile dysfunction. In this work, we randomly divided 140 males with erectile dysfunction and other diseases commonly associated with endothelial dysfunction like diabetes mellitus, hypertension and dyslipidaemia into two equal groups: treatment group, treated with 50mg daily oral avanafil, and control group, treated with placebo. The International Index of Erectile Function-5 score and the serum levels of nitric oxide, cyclic guanosine monophosphate and endothelin-1 as markers of endothelial function were measured at baseline and after four weeks of treatment in both groups. At the end of treatment period, those randomised to avanafil achieved statistically significant improvement in erectile function, nitric oxide, cyclic guanosine monophosphate and endothelin-1 levels from baseline versus placebo regardless the type and duration of associated comorbidity as well as the duration and severity of erectile dysfunction. These results permitted us to suggest that daily avanafil can improve the impaired endothelial function associated with the erectile dysfunction. 相似文献
69.
70.