全文获取类型
收费全文 | 376719篇 |
免费 | 24934篇 |
国内免费 | 2789篇 |
专业分类
耳鼻咽喉 | 5183篇 |
儿科学 | 8182篇 |
妇产科学 | 10075篇 |
基础医学 | 52831篇 |
口腔科学 | 11767篇 |
临床医学 | 29956篇 |
内科学 | 77844篇 |
皮肤病学 | 8540篇 |
神经病学 | 27067篇 |
特种医学 | 13899篇 |
外国民族医学 | 82篇 |
外科学 | 60431篇 |
综合类 | 9928篇 |
现状与发展 | 1篇 |
一般理论 | 64篇 |
预防医学 | 17297篇 |
眼科学 | 9413篇 |
药学 | 30902篇 |
1篇 | |
中国医学 | 2168篇 |
肿瘤学 | 28811篇 |
出版年
2021年 | 2373篇 |
2019年 | 2720篇 |
2018年 | 4514篇 |
2017年 | 3428篇 |
2016年 | 3516篇 |
2015年 | 4016篇 |
2014年 | 5691篇 |
2013年 | 7373篇 |
2012年 | 10011篇 |
2011年 | 10190篇 |
2010年 | 6177篇 |
2009年 | 5837篇 |
2008年 | 9449篇 |
2007年 | 10283篇 |
2006年 | 10201篇 |
2005年 | 9266篇 |
2004年 | 8772篇 |
2003年 | 8503篇 |
2002年 | 8171篇 |
2001年 | 28256篇 |
2000年 | 28761篇 |
1999年 | 23609篇 |
1998年 | 5026篇 |
1997年 | 4100篇 |
1996年 | 3680篇 |
1995年 | 3470篇 |
1994年 | 3099篇 |
1993年 | 2838篇 |
1992年 | 16035篇 |
1991年 | 14809篇 |
1990年 | 14152篇 |
1989年 | 13954篇 |
1988年 | 12578篇 |
1987年 | 12056篇 |
1986年 | 11097篇 |
1985年 | 10318篇 |
1984年 | 6908篇 |
1983年 | 5598篇 |
1982年 | 2716篇 |
1979年 | 5476篇 |
1978年 | 3345篇 |
1977年 | 2963篇 |
1975年 | 2636篇 |
1974年 | 3064篇 |
1973年 | 2863篇 |
1972年 | 2828篇 |
1971年 | 2773篇 |
1970年 | 2509篇 |
1969年 | 2543篇 |
1968年 | 2250篇 |
排序方式: 共有10000条查询结果,搜索用时 34 毫秒
31.
Harinakshi Sanikini David C. Muller Marisa Sophiea Sabina Rinaldi Antonio Agudo Eric J. Duell Elisabete Weiderpass Kim Overvad Anne Tjønneland Jytte Halkjær Marie-Christine Boutron-Ruault Franck Carbonnel Iris Cervenka Heiner Boeing Rudolf Kaaks Tilman Kühn Antonia Trichopoulou Georgia Martimianaki Anna Karakatsani Valeria Pala Domenico Palli Amalia Mattiello Rosario Tumino Carlotta Sacerdote Guri Skeie Charlotta Rylander María-Dolores Chirlaque López Maria-Jose Sánchez Eva Ardanaz Sara Regnér Tanja Stocks Bas Bueno-de-Mesquita Roel C.H. Vermeulen Dagfinn Aune Tammy Y.N. Tong Nathalie Kliemann Neil Murphy Marc Chadeau-Hyam Marc J. Gunter Amanda J. Cross 《International journal of cancer. Journal international du cancer》2020,146(4):929-942
Obesity has been associated with upper gastrointestinal cancers; however, there are limited prospective data on associations by subtype/subsite. Obesity can impact hormonal factors, which have been hypothesized to play a role in these cancers. We investigated anthropometric and reproductive factors in relation to esophageal and gastric cancer by subtype and subsite for 476,160 participants from the European Prospective Investigation into Cancer and Nutrition cohort. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox models. During a mean follow-up of 14 years, 220 esophageal adenocarcinomas (EA), 195 esophageal squamous cell carcinomas, 243 gastric cardia (GC) and 373 gastric noncardia (GNC) cancers were diagnosed. Body mass index (BMI) was associated with EA in men (BMI ≥30 vs. 18.5–25 kg/m2: HR = 1.94, 95% CI: 1.25–3.03) and women (HR = 2.66, 95% CI: 1.15–6.19); however, adjustment for waist-to-hip ratio (WHR) attenuated these associations. After mutual adjustment for BMI and HC, respectively, WHR and waist circumference (WC) were associated with EA in men (HR = 3.47, 95% CI: 1.99–6.06 for WHR >0.96 vs. <0.91; HR = 2.67, 95% CI: 1.52–4.72 for WC >98 vs. <90 cm) and women (HR = 4.40, 95% CI: 1.35–14.33 for WHR >0.82 vs. <0.76; HR = 5.67, 95% CI: 1.76–18.26 for WC >84 vs. <74 cm). WHR was also positively associated with GC in women, and WC was positively associated with GC in men. Inverse associations were observed between parity and EA (HR = 0.38, 95% CI: 0.14–0.99; >2 vs. 0) and age at first pregnancy and GNC (HR = 0.54, 95% CI: 0.32–0.91; >26 vs. <22 years); whereas bilateral ovariectomy was positively associated with GNC (HR = 1.87, 95% CI: 1.04–3.36). These findings support a role for hormonal pathways in upper gastrointestinal cancers. 相似文献
32.
Byung-Ho Yoon Lynne C. Jones Chung-Hwan Chen Edward Y. Cheng Quanjun Cui Wolf Drescher Wakaba Fukushima Valerie Gangji Stuart B. Goodman Yong-Chan Ha Philippe Hernigou Marc Hungerford Richard Iorio Woo-Lam Jo Vikas Khanduja Harry Kim Shin-Yoon Kim Tae-Young Kim Kyung-Hoi Koo 《The Journal of arthroplasty》2019,34(1):169-174.e1
Background
Although alcohol is a leading risk factor for osteonecrosis of the femoral head (ONFH) and its prevalence reportedly ranges from 20% to 45%, there are no unified classification criteria for this subpopulation. In 2015, Association Research Circulation Osseous decided to develop classification criteria for alcohol-associated ONFH.Methods
In June of 2017, Association Research Circulation Osseous formed a task force to conduct a Delphi survey. The task force invited 28 experts in osteonecrosis/bone circulation from 8 countries. Each round of the Delphi survey included questionnaires, analysis of replies, and feedback reports to the panel. After 3 rounds of the survey, consensus was reached on the classification criteria. The response rates for the 3 Delphi rounds were 100% (round 1), 96% (round 2), and 100% (round 3).Results
The consensus on the classification criteria of alcohol-associated ONFH included the following: (1) patients should have a history of alcohol intake >400 mL/wk (320 g/wk, any type of alcoholic beverage) of pure ethanol for more than 6 months; (2) ONFH should be diagnosed within 1 year after alcohol intake of this dose; and (3) patients should not have other risk factor(s).Conclusion
ARCO-established classification criteria to standardize clinical studies concerning AA-ONFH. 相似文献33.
In this paper, we use optimal parameter selection technique to develop two models involving single‐vendor–multiple‐buyer supply chain, which are called the dynamic independent optimization (DIO) model and the dynamic synchronized cycles (DSC) model, respectively. These models are, respectively, similar to the traditional static independent policy model and the traditional static synchronized cycle model, except that the deterministic demands of the buyers in the above two static models are now being replaced by the stochastic demands satisfying a Wiener process, which have more real‐life applications. Similar to the above static synchronized cycles model, the synchronization of the supply chain in our DSC model is also achieved by scheduling the delivery days of the buyers and coordinating them with the vendor's production cycle. Finding the optimal expected system costs of the DIO model and the DSC model involves solving optimal parameter selection problems governed by ordinary differential equations, whose final times are continuous decision variables and discrete decision variables, respectively. Computational methods have been developed for solving these problems. Numerical results show that the coordinated policy is better than the independent optimization policy, in terms of minimizing the expected system cost of the entire supply chain. Sensitivity analysis is performed to test the effect of changing the cost coefficients and the value on the performances of these models, where is the ratio of the total mean demand rate of all the buyers over the vendor's production rate. 相似文献
34.
35.
Y. Chen B. Bai H. Yan F. Wen D. Qin G. Jander Q. Xia G. Wang 《Insect molecular biology》2019,28(3):380-391
Isopentenylation at A37 (i6A37) of some transfer RNAs (tRNAs) plays a vital role in regulating the efficiency and fidelity of protein synthesis. However, whether insects, which are well known for their highly efficient protein synthesis machinery, employ this regulatory mechanism remains uninvestigated. In the current study, a candidate tRNA isopentenyltransferase (IPT) gene with three alternative splicing isoforms (BmIPT1–BmIPT3) was identified in Bombyx mori (silkworm). Only BmIPT1 could complement a yeast mutant lacking tRNA IPT. Phylogenetic analysis showed that silkworm tRNA IPT is conserved in the Lepidoptera. BmIPT was expressed in all B. mori tissues and organs that were investigated, but was expressed at a significantly higher level in silk glands of the fourth instar compared to the first day of the fifth instar. Interestingly, BmIPT was expressed at a significantly higher level in the domesticated silkworm, B. mori, than in wild Bombyx mandarina in multiple tissues and organs. Knock‐down of BmIPT by RNA interference caused severe abnormalities in silk spinning and metamorphosis. Constitutive overexpression of BmIPT1 using a cytoplasmic actin 4 promoter in B. mori raised its messenger RNA level more than sixfold compared with nontransgenic insects and led to significant decreases in the body weight and cocoon shell ratio. Together, these results confirm the first functional tRNA IPT in insects and show that a suitable expression level of tRNA IPT is vital for silk spinning, normal growth, and metamorphosis. Thus, i6A modification at position A37 in tRNA probably plays an important role in B. mori protein synthesis. 相似文献
36.
37.
Yücel Yüzbaşıoğlu Gülşah Çıkrıkçı Işık 《The American journal of emergency medicine》2019,37(9):1691-1693
IntroductionThe aim of this study was to compare the distribution and frequency of forensic medical events in a refugee group with that of the general population, and thus, extrapolate the problems encountered in the immigrant population.MethodsThose cases admitted to the emergency department (ED) for any reason that required a forensic examination between January 2016 and June 2018 were investigated retrospectively.ResultsA total of 310 refugees were admitted to the ED for forensic medical events. The most common nations of origin of the refugees were Iraq (n = 167), Syria (n = 65), and Afghanistan (n = 28). The median age of the refugees was 24 years old (interquartile range = 17–33). With regard to forensics, the most common reasons for the refugees to present to the ED were motor vehicle accidents 27.4%, assaults 25.8%, employment and industrial accidents 16.1%, and suicide attempts 10.3%. Other than suicide attempts, all of the forensic presentations were more common in the males. The outcomes of the refugee group were as follows: 92.3% were discharged, 5.8% were admitted to the hospital, 1% were admitted to the intensive care unit (ICU), and 1% were transferred. Suicide attempts were the most common reasons for the ICU admissions, while the most common reasons for the hospital admissions were orthopedic injuries.ConclusionIn general, the forensic event frequency in the refugee group was lower (p = 0.001); however, this was a single center study, and there could have been unrecorded cases due to an inability to access healthcare assistance, so these results may not be reliable. 相似文献
38.
Michelle Y L Tang Patrick H Y Chung Hau Y Chan Paul K H Tam Kenneth KY Wong 《Journal of pediatric surgery》2019,54(2):255-257
Objective
Helicobacter pylori infection is common among Asians. However, evidence in the recent years has demonstrated a decrease in the prevalence of H. pylori infection among children and adults worldwide. Our aim was to update its prevalence in symptomatic children in our locality in the recent 12?years and compared to the results of our previous review published in 2005.Methods
A retrospective review was carried out between 2005 and 2017. All children who presented with dyspepsia or gastrointestinal bleeding and underwent oesophagogastroduodenoscopy with antral biopsy taken were included. Patient demographics, endoscopic, or histological diagnosis and the H. pylori status were recorded.Main Results
A total of 602 patients were included. There was a statistically significant decreasing trend of H. pylori infection rate between 2005 and 2017 (p?=?0.003). The overall infection rate from this study was 12.8%, compared to 25.6% from our previous review. Overall failure of eradication with first-line antibiotic therapy has increased to 29.3% from 10% in our previous review.Conclusion
There was a decrease in the prevalence of H. pylori infection among symptomatic children for the recent 12?years, comparing to our previous data from 2005. We hypothesize that the reduction in prevalence of H. pylori infection among adults and the decrease in the practice of sharing chopsticks during meals have led to a decrease in transmission of the bacteria among family members in Hong Kong. However, the failure of eradication with first line treatment was higher, possibly due to the increase in antibiotics usage and resistance.Level of Evidence
III 相似文献39.
BackgroundWomen suffering from kidney disease are more prone to fertility problems, due to uremia. Fortunately, their fertility rate increases dramatically after renal transplantation. This study analyzes the predictors/risk factors of successful pregnancy with live birth outcome while presenting an overview of the 7-year experience of a single center.MethodsThis retrospective cohort study includes 239 women of reproductive age (18–40 years) who underwent renal transplantation in a tertiary Turkish clinic between October 1, 2011, and August 24, 2017. The subjects were invited to take part in a survey questioning their obstetric characteristics and they were assessed in 2 groups: fertile and infertile. Multivariable linear regression analysis was conducted to determine the predictors of a successful pregnancy.ResultsThirty-five 35 patients wished to become pregnant: 12 got pregnant spontaneously, while 21 failed to become pregnant (spontaneously). The mean age of the patients at the survey was 34 ± 7. Regular menstrual cycles after renal transplantation, tacrolimus-mycophenolate mofetil maintenance protocol, and age at transplantation were found to be predictors of spontaneous pregnancy. The duration of peritoneal dialysis was significantly longer in the infertile group (48 vs 12 months).ConclusionEnd-stage renal disease's negative impacts, including menstrual abnormality and fertility problems, can be overcome by successful kidney transplantation with appropriate immunosuppression. Minimizing the duration of peritoneal dialysis, particularly in patients who desire future fertility, may be accepted as a logical management strategy. 相似文献
40.