全文获取类型
收费全文 | 1712篇 |
免费 | 111篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 138篇 |
妇产科学 | 13篇 |
基础医学 | 189篇 |
口腔科学 | 49篇 |
临床医学 | 168篇 |
内科学 | 542篇 |
皮肤病学 | 14篇 |
神经病学 | 86篇 |
特种医学 | 256篇 |
外科学 | 113篇 |
综合类 | 20篇 |
预防医学 | 92篇 |
眼科学 | 14篇 |
药学 | 56篇 |
肿瘤学 | 99篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 23篇 |
2017年 | 15篇 |
2016年 | 31篇 |
2015年 | 18篇 |
2014年 | 31篇 |
2013年 | 29篇 |
2012年 | 51篇 |
2011年 | 46篇 |
2010年 | 48篇 |
2009年 | 39篇 |
2008年 | 35篇 |
2007年 | 67篇 |
2006年 | 69篇 |
2005年 | 63篇 |
2004年 | 57篇 |
2003年 | 58篇 |
2002年 | 38篇 |
2001年 | 52篇 |
2000年 | 43篇 |
1999年 | 46篇 |
1998年 | 76篇 |
1997年 | 84篇 |
1996年 | 89篇 |
1995年 | 56篇 |
1994年 | 50篇 |
1993年 | 52篇 |
1992年 | 38篇 |
1991年 | 30篇 |
1990年 | 46篇 |
1989年 | 61篇 |
1988年 | 63篇 |
1987年 | 52篇 |
1986年 | 67篇 |
1985年 | 48篇 |
1984年 | 29篇 |
1983年 | 28篇 |
1982年 | 18篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 4篇 |
1977年 | 13篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1950年 | 1篇 |
排序方式: 共有1851条查询结果,搜索用时 15 毫秒
51.
This study was designed to compare the growth of Pakistani schoolchildren in the UK with the 1990 UK growth standards. Measurements of height, weight, and sitting height were performed on 785 Pakistani schoolchildren aged 5-14 years with the mean values for each age and sex being plotted on the UK growth standards. The results were expressed as SD scores relative to the 1990 reference data. The mean height for the boys was only 0.2 SD scores below the mean for the new growth standards with the mean height for the girls being 0.4 SD scores below the mean. The mean values for weight and body mass index were 0.3 and 0.5 SD scores less than the mean for boys and girls respectively. This study demonstrates that the growth of Pakistani schoolchildren in the UK is comparable to the 1990 UK growth standards with only minor differences. It is not safe to assume that short stature or low body weight in a Pakistani child is due to his or her ethnic background. 相似文献
52.
OBJECTIVE: The ketogenic diet is a high-fat, low-protein, low-carbohydrate diet developed in the 1920s for the treatment of children with difficult to control seizures. Despite advances in both the pharmacotherapy and the surgery of epilepsy, many children continue to have difficult-to-control seizures. This prospective study sought to determine the ketogenic diet's effectiveness and tolerability in children refractory to today's medications. METHODS: One hundred fifty consecutive children, ages 1 to 16 years, virtually all of whom continued to have more than two seizures per week despite adequate therapy with at least two anticonvulsant medications, were prospectively enrolled in this study, treated with the ketogenic diet, and followed for a minimum of 1 year. Seizure frequency was tabulated from patients' daily seizure calendars and seizure reduction calculated as percentage of baseline frequency. Adverse events and reasons for diet discontinuation were recorded. RESULTS: The children (mean age, 5.3 years), averaged 410 seizures per month before the diet, despite an exposure to a mean of 6.2 antiepileptic medications. Three months after diet initiation, 83% of those starting remained on the diet and 34% had >90% decrease in seizures. At 6 months, 71% still remained on the diet and 32% had a >90% decrease in seizures. At 1 year, 55% remained on the diet and 27% had a >90% decrease in seizure frequency. Most of those discontinuing the diet did so because it was either insufficiently effective or too restrictive. Seven percent stopped because of intercurrent illness. CONCLUSIONS: The ketogenic diet should be considered as alternative therapy for children with difficult-to-control seizures. It is more effective than many of the new anticonvulsant medications and is well tolerated by children and families when it is effective. 相似文献
53.
Zusammenfassung
Fragestellung: Welchen Stellenwert hat die Ultraschalluntersuchung des Fetus und Neugeborenen bei der Diagnosestellung und Therapieplanung
einer Mekoniumperitonitis.
Patienten und Methode: Wir berichten über die sonographischen Befunde von 8 Kindern mit einer Mekoniumperitonitis und beschreiben die Korrelationen
zwischen den sonographischen Befunden und der zugrundeliegenden Darmerkrankung bzw. dem klinischen Verlauf.
Ergebnisse: Bei 7 Patienten wurde die Diagnose bereits pr?natal vermutet. Sonographische Befunde zum Zeitpunkt der Geburt waren Mekoniumpseudozysten
(n=6), diffuse intraabdominale Verkalkungen (n=4), ein Polyhydramnion (n=6), ein Aszites (n=3), dilatierte Darmschlingen (n=5) und multiple intrahepatische Mekoniumzysten (n=1). Polyhydramnion und dilatierte Darmschlingen waren immer mit einer intestinalen Stenose bzw. Atresie assoziiert.
Schlu?folgerung: Neugeborene mit einer Mekoniumperitonitis zeigen ein charakteristisches Spektrum an sonographischen Befunden, welche neben
dem klinischen und radiologischen Befund für die postnatalen therapeutischen überlegungen wichtig sind.
相似文献
54.
A prospective study of methylenetetrahydrofolate reductase and methionine synthase gene polymorphisms, and risk of colorectal adenoma 总被引:8,自引:2,他引:8
Chen J; Giovannucci E; Hankinson SE; Ma J; Willett WC; Spiegelman D; Kelsey KT; Hunter DJ 《Carcinogenesis》1998,19(12):2129-2132
We examined the relationship between a functional polymorphism (667C--
>T, ala-->val) of the methylenetetrahydrofolate reductase gene
(MTHFR) and the risk of colorectal adenomas in the prospective Nurses'
Health Study. Among 257 incident polyp cases and 713 controls, the MTHFR
val/val polymorphism [relative risk (RR) = 1.35, 95% confidence interval
(CI) 0.84-2.17] was not significantly associated with risk of adenomas.
This lack of association was observed for both small (RR = 1.36, 95% CI
0.76-2.45) and large (RR = 1.32, 95% CI 0.66-2.66) adenomas. Furthermore,
there was no significant interaction between this polymorphism and
consumption of either folate, methionine or alcohol. We also examined the
relationship of a newly identified polymorphism (asp919gly) of the
methionine synthase gene (MS) with the risk of colorectal adenomas in the
same population. The MS gly/gly polymorphism was also not significantly
associated with risk of colorectal adenomas (RR = 0.66, 95% CI 0.26-1.70).
These results, which need to be confirmed in other studies, suggest that
the MTHFR val/val polymorphism, which has been previously inversely
associated with risk of colorectal cancer, plays a role only in a late
stage (adenoma-- >carcinoma) of colorectal tumorigenesis, and/or may
protect against malignant transformation in the subset of benign adenomas,
which may progress to malignancy.
相似文献
55.
56.
High IGFBP-3 levels in marrow plasma in early-stage MDS: effects on apoptosis and hemopoiesis. 总被引:1,自引:0,他引:1
The pathophysiology of the myelodysplastic syndromes (MDS) is incompletely understood. Tumor necrosis factor (TNF)alpha levels are elevated, particularly in early-stage MDS, and apoptosis in marrow cells is upregulated. Observations in other models have shown a role for insulin-like growth factor binding protein 3 (IGFBP-3) in TNFalpha-mediated apoptosis. We observed increased levels of IGFBP-3 in the marrow plasma of patients with MDS (P = 0.005) and hypothesized that altered IGFBP-3 levels contribute to the dysregulation of hemopoiesis in MDS by affecting proliferation and apoptosis. Western analysis of marrow plasma from MDS patients revealed an increase in the ratio of intact vs fragmented IGFBP-3 in early-stage MDS (relative to controls) that decreased with MDS disease progression, suggesting increased proteolysis with more advanced disease. Thus, these results provide evidence for dysregulation of IGFBP-3 in patients with MDS. While the data are complex, they are consistent with a modulatory effect of IGFBP-3 on hemopoiesis in MDS. Conceivably, understanding these mechanisms may allow for the development of novel therapeutic strategies. 相似文献
57.
Johannes Deeg Alexander Loizides Wolfgang Löscher Alexandra Zangerle Hannes Gruber 《Ultrasound in medicine & biology》2021,47(7):1970-1975
Repetitive vibratory trauma in cyclists is one of the most common causes of ulnar nerve compression at the wrist. This study describes five cases of clinically suspected compression syndrome of the deep terminal branch of the ulnar nerve (DBUN) defined by high-resolution ultrasound (HRUS) with a 18-MHz linear transducer. Reliable HRUS visualization of the DBUN was feasible in all patients. The affected nerves had focally swollen and hypo-echoic changed segments. HRUS is a good imaging tool for the evaluation of a suspicious DBUN neuropathy if no electrodiagnostic testing is available or in patients with mild to moderate clinical symptoms with inconclusive electrodiagnostic results. 相似文献
58.
59.
60.
Flow cytometry for diagnosis and assessment of prognosis in patients with myelodysplastic syndromes 总被引:2,自引:0,他引:2
The Myelodysplastic Syndrome (MDS) comprises a spectrum of hematopoietic stem cell disorders. Identification of additional parameters that might distinguish different risk groups or entities would be useful. Flow cytometric studies have begun to characterize individual or composite immunophenotypic abnormalities as well as light scatter properties that may be helpful for diagnosis and of prognostic value for the natural course of the disease and for outcome after therapy. Here we review the current state of the art of the use of flow cytometry in patients with MDS. 相似文献