全文获取类型
收费全文 | 4521篇 |
免费 | 349篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 173篇 |
妇产科学 | 102篇 |
基础医学 | 557篇 |
口腔科学 | 82篇 |
临床医学 | 476篇 |
内科学 | 1041篇 |
皮肤病学 | 61篇 |
神经病学 | 327篇 |
特种医学 | 131篇 |
外科学 | 711篇 |
综合类 | 99篇 |
一般理论 | 3篇 |
预防医学 | 353篇 |
眼科学 | 158篇 |
药学 | 284篇 |
1篇 | |
中国医学 | 18篇 |
肿瘤学 | 277篇 |
出版年
2023年 | 30篇 |
2022年 | 35篇 |
2021年 | 92篇 |
2020年 | 66篇 |
2019年 | 86篇 |
2018年 | 113篇 |
2017年 | 92篇 |
2016年 | 82篇 |
2015年 | 102篇 |
2014年 | 126篇 |
2013年 | 203篇 |
2012年 | 227篇 |
2011年 | 227篇 |
2010年 | 145篇 |
2009年 | 134篇 |
2008年 | 257篇 |
2007年 | 269篇 |
2006年 | 271篇 |
2005年 | 238篇 |
2004年 | 253篇 |
2003年 | 231篇 |
2002年 | 233篇 |
2001年 | 59篇 |
2000年 | 65篇 |
1999年 | 56篇 |
1998年 | 46篇 |
1997年 | 49篇 |
1995年 | 33篇 |
1993年 | 29篇 |
1992年 | 30篇 |
1991年 | 42篇 |
1990年 | 34篇 |
1989年 | 36篇 |
1988年 | 33篇 |
1987年 | 39篇 |
1986年 | 35篇 |
1985年 | 38篇 |
1984年 | 53篇 |
1983年 | 59篇 |
1982年 | 53篇 |
1981年 | 60篇 |
1980年 | 54篇 |
1979年 | 34篇 |
1978年 | 35篇 |
1977年 | 39篇 |
1976年 | 34篇 |
1975年 | 26篇 |
1973年 | 26篇 |
1972年 | 24篇 |
1971年 | 27篇 |
排序方式: 共有4908条查询结果,搜索用时 15 毫秒
41.
Yong Zhi Khow Graham S. Goh Jerry Yongqiang Chen Ngai Nung Lo Seng Jin Yeo Ming Han Lincoln Liow 《The Journal of arthroplasty》2021,36(6):1974-1979
BackgroundPrevious studies evaluating weight changes following total knee arthroplasty (TKA) were performed on heterogenous cohorts. However, no study has evaluated weight changes in a cohort of simultaneous-bilateral TKA (SB-TKA) patients. This study aimed to evaluate the prevalence of patients who lost or gained weight, determine if postoperative weight change influences functional outcome, and identify predictors of weight change after SB-TKA.MethodsProspectively collected registry data of 560 patients who underwent SB-TKA were reviewed. Patients were assessed preoperatively, at 6 months, and 2 years using the Knee Society Score, Oxford Knee Score, Short-Form 36, and range of motion. Change in body mass index (BMI) >5% was used to categorize patients into 3 groups: lost, maintained, or gained weight. Analysis of variance, Kruskal-Wallis test, and chi-squared test were used to compare functional outcomes between groups. Multivariable logistic regression evaluated predictors for postoperative weight changes.ResultsAt 2 years, 59% of patients maintained weight, 28% of patients gained weight, and 13% of patients lost weight. All groups experienced similar improvements in functional outcomes, rates of minimal clinically important difference attainment, and patient satisfaction (P > .05). Older patients were more likely to gain weight (P < .05). Patients with higher preoperative BMI were more likely to gain weight (P < .05) and less likely to lose weight (P < .05). Patients with greater preoperative comorbidities were less likely to lose weight (P < .05).ConclusionUp to 41% of patients experience significant weight changes after SB-TKA. Older patients with higher preoperative BMI were more likely to gain weight, while higher preoperative BMI with more comorbidities were less likely to lose weight following SB-TKA; however, postoperative weight changes do not appear to affect functional outcomes.Level of EvidenceIII, therapeutic study. 相似文献
42.
S Y Melvin 《Primary care》1990,17(1):47-57
Syphilis has persisted for centuries, yet over the last few years with public emphasis on "safe sex" practices there is still a resurgence of this disease. Control of this potentially devastating illness cannot be achieved by physicians alone. It requires a combined effort from the public, educators, government, and the medical community. Physicians may contribute by patient education, frequent testing of all individuals at high risk, and treatment and close follow-up of patients and contacts. 相似文献
43.
Yang Weilian Barth Rolf F. Rotaru Joan H. Moeschberger Melvin L. Joel Darrel D. Nawrocky Marta M. Goodman Joseph H. 《Journal of neuro-oncology》1997,33(1-2):59-70
Boronophenylalanine (BPA) has been used for boron neutron capture therapy (BNCT) of brain tumors in both experimental animals and humans. The purpose of the present study was to determine if the efficacy of BNCT could be enhanced by means of intracarotid (i.c.) injection of BPA with or without blood-brain barrier disruption (BBB-D) and neutron irradiation using a rat brain tumor model. For biodistribution studies, F98 glioma cells were implanted stereotactically into the brains of Fischer rats, and12 days later BBB-D was carried out by i.c. infusion of 25% mannitol (1.373 mOsmol/ml), followed immediately by i.c. administration of 300, 500 or 800 mg of BPA/kg body weight (b.w.). At the 500 mg dose a fourfold increase in tumor boron concentration (94.5 g/g) was seen at 2.5 hours after BBB-D, compared to 20.8 g/g in i.v. injected animals. The best composite tumor to normal tissue ratios were observed at 2.5 hours after BBB-D, at which time the tumor: blood (T: Bl) ratio was10.9, and the tumor: brain (T: Br) ratio was 7.5, compared to 3.2 and 5.0 respectively for i.v. injected rats. In contrast, animals that had received i.c. BPA without BBB-D had T: Bl and T: Br ratios of 8.5 and 5.9, respectively, and the tumor boron concentration was 42.7g/g. For therapy experiments, initiated 14 days after intracerebral implantation of F98 glioma cells, 500 mg/kg b.w. of BPA were administered i.v. or i.c. with or without BBB-D, and the animals were irradiated 2.5 hourslater at the Brookhaven Medical Research Reactor with a collimated beam of thermal neutrons delivered to the head. The mean survival time for untreated control rats was 24 ± 3 days, 30 ± 2 days for irradiated controls, 37 ± 3 days for those receiving i.v. BPA, 52 ± 15 days for rats receiving i.c. BPA without BBB-D, and 95 ± 95 days for BBB-D followed by i.c. BPA and BNCT. The latter group had a 246% increase in life span (ILS) compared to untreated controls and a 124% ILS compared to that of i.v. injected animals. These survival data are the best ever obtained with the F98 glioma model and suggest that i.c. administration of BPA with or without BBB-D may be useful as a means to increase the efficacy of BNCT. 相似文献
44.
Background: Recent data suggest that children have a higher incidence of recurrence than adults after nonoperative treatment of primary
spontaneous pneumothorax (PSP). Video-assisted thoracoscopic surgery (VATS) allows efficacious therapy with significantly
less morbidity. We attempt to define the most cost-effective clinically efficacious strategy using VATS to manage pediatric
PSP.
Methods: We retrospectively reviewed all admissions to a tertiary care children's hospital for PSP between January 1, 1991 and June
30, 1996.
Results: Fifteen children had 29 primary or recurrent PSPs. Mean patient age was 14.8 ± 1.1 years, boy–girl ratio 4:1, median body
mass index 18 (normal, 20–25), and 67% of pneumothoraces left sided. All patients were managed initially nonoperatively: 14
with tube thoracostomy drainage and 1 with oxygen alone. Of the children initially managed nonoperatively, 57% had a recurrent
pneumothorax, and 50% of these patients eventually developed contralateral pneumothoraces. Nonoperative treatment for recurrence
resulted in a 75% second recurrence rate. In contrast, eight children who underwent operative management had a 9% incidence
of recurrence. The total for charges accrued in treating 29 pneumothoraces in these 15 patients was approximately $315,000.
In the same population, the estimated charges for initial nonoperative therapy followed by bilateral thoracoscopy after a
single recurrence would be $230,000.
Conclusions: A cost-effective treatment strategy for pediatric primary spontaneous pneumothorax is tube thoracostomy at first presentation,
followed by VATS with thoracoscopic bleb resection and pleurodesis for patients who experience recurrent pneumothorax.
Received: 15 May 1998/Accepted: 15 January 1999 相似文献
45.
46.
47.
Kurt Schneider Melvin R. Kinlow A. N. Galloway Don L. Ferro 《Child & youth care forum》1982,11(4):298-311
The effects of implementing the Teaching-Family Model in two community-based group homes were assessed through a series of pre-post measures. Data analysis indicates substantial positive change in youth social skills, program quality, youth and staff satisfaction levels, social climate, and staff accountability for care of the children.Requests for reprints, samples of the Staff Accountability Scale, and other forms or the questionnaires in this study should be addressed to Kurt Scheider at The Maryville Academy, 1150 North River Road, Des Plaines, IL 60016 相似文献
48.
Tami S McMullin Melvin E Andersen Alan Nagahara Trent D Lund Toni Pak Robert J Handa William H Hanneman 《Toxicological sciences》2004,79(2):278-286
High oral doses of atrazine (ATRA) disrupt normal neuroendocrine function, resulting in suppression of the luteinizing hormone (LH) surge in adult, ovariectomized (OVX) estrogen-primed female rats. While the mechanism by which ATRA inhibits LH secretion is not known, current data indicate that ATRA does have anti-estrogenic properties in vitro and in vivo. In the body, ATRA is rapidly converted to diaminochlorotriazine (DACT). The present study was conducted to investigate the effects of ATRA and DACT on the estradiol benzoate (EB)/progesterone (P) induced LH surge and to determine if such changes correlate with impaired estrogen receptor (ER) function. ATRA, administered by gavage for five consecutive days to adult OVX, female Sprague-Dawley rats, caused a dose-dependent suppression of the EB/P induced LH surge. Although to a lesser degree than ATRA, DACT significantly suppressed total plasma LH and peak LH surge levels in EB/P primed animals by 60 and 58%, respectively. DACT treatment also decreased release of LH from the pituitary in response to exogenous gonadotropin releasing hormone (GnRH) by 47% compared to control. Total plasma LH secretion was reduced by 37% compared to control, suggesting that in addition to potential hypothalamic dysfunction, pituitary function is altered. To further investigate the mechanism by which hypothalamic function might be altered, potential anti-estrogenicity of ATRA and DACT were assessed by evaluating ER function treated rats. Using an in vitro receptor binding assay, ATRA, but not DACT, inhibited binding of [(3)H]-estradiol to ER. In contrast, ATRA, administered to female rats under dosing conditions which suppressed the LH surge, neither changed the levels of unoccupied ER nor altered the estrogen induced up-regulation of progesterone receptor mRNA. Collectively, these results indicate that although ATRA is capable of binding ER in vitro, the suppression of LH after treatment with high doses of ATRA is not due to alterations of hypothalamic ER function. 相似文献
49.
Christopher O. Audu William J. Melvin Amrita D. Joshi Sonya J. Wolf Jadie Y. Moon Frank M. Davis Emily C. Barrett Kevin D. Mangum Hongping Deng Xianying Xing Rachel Wasikowski Lam C. Tsoi Sriganesh B. Sharma Tyler M. Bauer James Shadiow Matthew A. Corriere Andrea T. Obi Steven L. Kunkel Benjamin Levi Bethany B. Moore Johann E. Gudjonsson Andrew M. Smith Katherine A. Gallagher 《Cellular & molecular immunology》2022,19(11):1251
50.
Objective Edible bird’s nest (EBN) is a popular traditional tonic food in Chinese population for centuries. Malaysia is one of the main EBN suppliers in the world. This study aims to explore the best strategy to boost the antioxidant potential of EBN solution. Methods In this study, the raw EBN (4%, mass to volume ratio) was initially enzymatic hydrolyzed using papain enzyme to produce EBN hydrolysate (EBNH), then spray-dried into powdered form. Next, 4% (mass to volume ratio) of EBNH powder was dissolved in ginger extract (GE), mulberry leaf extract (MLE) and cinnamon twig extract (CTE) to detect the changes of antioxidant activities, respectively. Results Results obtained suggest that enzymatic hydrolysis significantly reduced the viscosity of 4% EBN solution from (68.12 ± 0.69) mPa.s to (7.84 ± 0.31) mPa.s. Besides, the total phenolic content (TPC), total flavonoid content (TFC), total soluble protein, DPPH scavenging activity and ferric reducing antioxidant power (FRAP) were substantially increased following EBN hydrolysis using papain enzyme. In addition, fortification with GE, MLE and CTE had further improved the TPC, TFC, DPPH scavenging activity and FRAP of the EBNH solution. Among the samples, MLE-EBNH solution showed the most superior antioxidant potential at (86.39 ± 1.66)% of DPPH scavenging activity and (19.79 ± 2.96) mmol/L FeSO4 of FRAP. Conclusion This study proved that combined enzymatic hydrolysis and MLE fortification is the best strategy to produce EBN product with prominent in vitro antioxidant potential. This preliminary study provides new insight into the compatibility of EBN with different herbal extracts for future health food production. 相似文献