全文获取类型
收费全文 | 515篇 |
免费 | 20篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 31篇 |
妇产科学 | 6篇 |
基础医学 | 54篇 |
口腔科学 | 3篇 |
临床医学 | 54篇 |
内科学 | 84篇 |
皮肤病学 | 3篇 |
神经病学 | 30篇 |
特种医学 | 97篇 |
外科学 | 69篇 |
综合类 | 7篇 |
预防医学 | 25篇 |
眼科学 | 2篇 |
药学 | 49篇 |
中国医学 | 1篇 |
肿瘤学 | 23篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 15篇 |
2018年 | 8篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 21篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 6篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 17篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 15篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 19篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1972年 | 4篇 |
1970年 | 3篇 |
1968年 | 6篇 |
1966年 | 4篇 |
排序方式: 共有539条查询结果,搜索用时 15 毫秒
1.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
2.
顾性初 《中国医药工业杂志》1995,(11)
抑制幽门螺杆菌产生的脲酶具有治疗胃炎和消化性溃疡的作用。用酚红指示剂和Berthelot试剂在96孔培养板上检测重组脲酶活性,其灵敏度指标酚红法每mg酶蛋白引起的每分钟吸光度变化。△A为6.9,而Berthelot法每mg酶蛋白引起的每分钟吸光度比值变化△A为313。结果表明用Berthelot试剂检测重组脲酶活性适宜在96孔培养板上大规模筛选天然产物中的脲酶抑制剂。 相似文献
3.
W D Foltz Y Yang J J Graham J S Detsky G A Wright A J Dick 《Magnetic resonance in medicine》2006,56(6):1311-1319
MRI evaluations of intramyocardial hemorrhage in acute infarction have relied on T(2) and T(2)(*) shortening only. We propose a more comprehensive evaluation of hemorrhagic infarction based on the concept that fluctuations in T(2) and T(1) relaxation in acute reperfused infarction will reflect transient edema and hemoglobin oxidative denaturation to uncompartmentalized methemoglobin. Anteroapical infarction was created via percutaneous balloon in young swine (22-25 kg, N = 12). T(2), T(1), diastolic wall thickness (DWT), and the Gd-DTPA partition coefficient (lambda) were measured on days 0, 2, and 7. DWT was elevated at 1 hr postreperfusion (128% +/- 53%, P = 0.0001), and alleviated on days 2 and 7 (48% +/- 10%, P = 0.008; 53% +/- 24%, P = 0.003). T(2) and T(1) elevations were coincident with early edema (DeltaT(2) = 55% +/- 24%, P < 0.0001; DeltaT(1) = 27% +/- 18%, P < 0.04). T(2) and T(1) were nearly normal on day 2 (DeltaT(2) = 8% +/- 8%, P = 0.27; DeltaT(1) = 0% +/- 1%, P = 0.65). On day 7, T(2) increased while T(1) decreased (DeltaT(2) = 27% +/- 16%, P = 0.005; DeltaT(1) = -14% +/- 10%, P = 0.02). Lambda was elevated by >150% at all time points (P < or = 0.002). Histology verified hemorrhagic injury. T(1) and T(2) fluctuations are consistent with transient edema, as well as hemoglobin oxidative denaturation to decompartmentalized methemoglobin. This methodological development may broaden our understanding of hemorrhagic microvascular injury and improve its detection in clinical populations. 相似文献
4.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
5.
Day DJ; Speiser PW; Schulze E; Bettendorf M; Fitness J; Barany F; White PC 《Human molecular genetics》1996,5(12):2039-2048
Steroid 21-hydroxylase deficiency is among the most common inborn errors of
metabolism in man. Characterization of mutations in the 21- hydroxylase
gene (CYP21) has permitted genetic diagnosis, facilitated by the polymerase
chain reaction (PCR). The most common mutation is conversion of an A or C
at nt656 to a G in the second intron causing aberrant splicing of mRNA.
Homozygosity for nt656G is associated with profoundly deficient adrenal
cortisol and aldosterone synthesis, secondary hypersecretion of adrenal
androgens, and a severe form of congenital adrenal hyperplasia (CAH)
characterized by ambiguous genitalia and/or sodium wasting in newborns.
During the course of genetic analysis of CYP21 mutations in CAH families,
we and others have noticed a number of relatives genotyped as nt656G
homozygotes, yet showing no clinical signs of disease. A number of lines of
evidence have led us to propose that the putative asymptomatic nt656G/G
individuals are incorrectly typed due to dropout of one haplotype during
PCR amplification of CYP21. For prenatal diagnosis, we recommend that
microsatellite typing be used as a supplement to CYP21 genotyping in order
to resolve ambiguities at nt656.
相似文献
6.
The physiological role of the amphibian paraphysis was studied by removing the paraphysis from bullfrog tadpoles (Rana catesbeiana) and observing change in frog weight, bone development, and parathyroid glands 22 months later. Development was similar in control and paraphysectomized frogs until 6 months when the experimental frogs began to show greater weight gain which persisted for the remaining 16 months. At the time of sacrifice (22 months after paraphysectomy), the parathyroid glands of the experimental frogs were enlarged with a tenfold increase in wet weight and a sevenfold increase in dry weight. The glands from experimental frogs had numerous cysts filled with eosinophilic staining material; histologically the cell nuclei were rounded and the cytoplasm was vesiculated. At the time of sacrifice the experimental frogs had knoblike deformities along the shafts of the long bones. These deformities were due to callus formation around spontaneous bone fractures as revealed by X-rays of the tibia-fibulas and femurs. The dry weight was greater but calcium content less in femurs from experimental frogs. These findings indicate the paraphysis plays a role in calcium metabolism, possibly by producing a factor necessary for calcium action on cells. 相似文献
7.
Foltz AM 《Health policy and planning》1994,9(4):371-384
During the past 10 years, donors have recognized the need for major reforms to achieve sustainable development. Using non-project assistance they have attempted to leverage reforms by offering financing conditioned on the enactment of reform. The experience of USAID's health reform programmes in Niger and Nigeria suggest these programmes have proved more difficult to implement than expected. When a country has in place a high level of fiscal accountability and high institutional capacity, programmes of conditioned non-project assistance may be more effective in achieving reforms than traditional project assistance. However, when these elements are lacking, as they were in Niger, non-project assistance offers nothing inherently superior than traditional project assistance. Non-project assistance may be most effective for assisting the implementation of policy reforms adopted by the host government. 相似文献
8.
S A Reuschel S E Percey S Liu D M Eades R L Foltz 《Journal of analytical toxicology》1999,23(5):306-312
An assay has been developed for quantitative determination of lysergic acid diethylamide (LSD) and a major metabolite of LSD in human urine at concentrations as low as 10 pg/mL. In most LSD-positive urine samples the metabolite, 2-oxo-3-hydroxy-LSD, is present at higher concentrations than LSD and can be detected for a longer time than LSD after ingestion of the drug. Urine samples are extracted using Varian Bond Elut Certify extraction cartridges. Confirmatory identification is accomplished by trimethylsilylation of LSD and 2-oxo-3-hydroxy-LSD, followed by gas chromatography-tandem mass spectrometry analysis using positive ion chemical ionization and selected reaction monitoring. Commercially available lysergic acid methylpropylamide and 2-oxo-3-hydroxy-LAMPA are used as internal standards. With selected reaction monitoring, both compounds gave linear calibration curves from 10 pg/mL to 5000 pg/mL. Forty-nine human urine samples that had previously been shown to contain LSD were reanalyzed by the new method. These samples showed an average LSD concentration of 357 pg/mL and an average 2-oxo-3-hydroxy-LSD concentration of 3470 pg/mL. Additional experiments using clinical samples in which two subjects were dosed with LSD support the conclusion that analysis for 2-oxo-3-hydroxy-LSD can permit identification of LSD users for a longer period following ingestion than analysis for the parent drug. 相似文献
9.
JP Bound PW Harvey BJ Francis F Awwad AC Gatrell 《Archives of disease in childhood》1997,76(2):107-112
OBJECTIVE: To analyse the prevalence of neural tube defects in small geographical areas and seek to explain any spatial variations with reference to environmental lead and deprivation. SETTING: The Fylde of Lancashire in the north west of England. DESIGN: Cases were ascertained as part of a prospective survey of major congenital malformations in babies born in the Fylde to residents there between 1957 and 1981. A matched case-control analysis used infants with cardiovascular system, alimentary tract, and urinary system malformations as controls. Conditional logistic regression was used to assess the effects of more than 10 micrograms/l lead in drinking water and the Townsend deprivation score. RESULTS: The prevalence of neural tube defects in 1957-73 was higher in Blackpool, Fleetwood, and North Fylde, whereas the three control groups showed no significant spatial variation. In 1957-81 mothers living in electoral wards with either a higher proportion of houses with more than 10 micrograms/l lead in the water or a higher deprivation score had a greater risk of having a baby with a neural tube defect. For spina bifida and cranium bifidum alone, this was also true. For anencephaly, deprivation was less important although the effect of lead was still seen. In some neural tube defects, lead may act independently of other possible factors associated with deprivation. It seemed unlikely that lead levels changed significantly during the survey. The percentage of houses with 10 micrograms/l or more of lead in the water in 1984-5 was similar to that found in Great Britain 10 years previously. CONCLUSION: There is evidence to suggest that lead is one cause of neural tube defects, especially anencephaly. This could link the known preventive actions of hard water and folic acid. Calcium is a toxicological antagonist of lead. One cause of a deficiency of folic acid is impaired absorption secondary to zinc deficiency, which may be produced or exacerbated by lead. 相似文献
10.