全文获取类型
收费全文 | 397篇 |
免费 | 14篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 26篇 |
妇产科学 | 5篇 |
基础医学 | 25篇 |
口腔科学 | 11篇 |
临床医学 | 38篇 |
内科学 | 81篇 |
皮肤病学 | 15篇 |
神经病学 | 14篇 |
特种医学 | 54篇 |
外科学 | 43篇 |
综合类 | 59篇 |
预防医学 | 12篇 |
眼科学 | 2篇 |
药学 | 32篇 |
肿瘤学 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 19篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 29篇 |
1997年 | 35篇 |
1996年 | 30篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 18篇 |
1992年 | 5篇 |
1990年 | 4篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 13篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有440条查询结果,搜索用时 15 毫秒
11.
CJ Stewart ECL Marrs S Magorrian A Nelson C Lanyon JD Perry ND Embleton SP Cummings JE Berrington 《Acta paediatrica (Oslo, Norway : 1992)》2012,101(11):1121-1127
Aim: To describe gut colonization in preterm infants using standard culture and 16S gene rRNA profiling, exploring differences in healthy infants and those who developed NEC/late onset sepsis (LOS). Methods: Ninety‐nine stools from 38 infants of median 27‐week gestation were cultured; 44 stools from 27 infants had their microbial profiles determined by 16S. Ordination analyses explored effects of patient variables on gut communities. Results: Standard microbiological culture identified a mean of two organisms (range 0–7), DGGE 12 (range 3–18) per patient. Enterococcus faecalis and coagulase negative staphylococci (CONS) were most common by culture (40% and 39% of specimens). Meconium was not sterile. No fungi were cultured. Bacterial community structures in infants with NEC and LOS differed from healthy infants. Infants who developed NEC carried more CONS (45% vs 30%) and less Enterococcus faecalis (31% vs 57%). 16S identified Enterobacter and Staphylococcus presence associated with NEC/LOS, respectively. Conclusions: Important differences were found in the gut microbiota of preterm infants who develop NEC/LOS. The relationship of these changes to current practices in neonatal intensive care requires further exploration. 相似文献
12.
Preliminary observations on polar body extrusion and pronuclear formation in human oocytes using time-lapse video cinematography 总被引:10,自引:17,他引:10
Payne D; Flaherty SP; Barry MF; Matthews CD 《Human reproduction (Oxford, England)》1997,12(3):532-541
In this study, we have used time-lapse video cinematography to study
fertilization in 50 human oocytes that had undergone intracytoplasmic sperm
injection (ICSI). Time-lapse recording commenced shortly after ICSI and
proceeded for 17-20 h. Oocytes were cultured in an environmental chamber
which was maintained under standard culture conditions. Overall, 38 oocytes
(76%) were fertilized normally, and the fertilization rate and embryo
quality were not significantly different from 487 sibling oocytes cultured
in a conventional incubator. Normal fertilization followed a defined course
of events, although the timing of these events varied markedly between
oocytes. In 35 of the 38 fertilized oocytes (92%), there were circular
waves of granulation within the ooplasm which had a periodicity of 20-53
min. The sperm head decondensed during this granulation phase. The second
polar body was then extruded, and this was followed by the central
formation of the male pronucleus. The female pronucleus formed in the
cytoplasm adjacent to the second polar body at the same time as, or
slightly after, the male pronucleus, and was subsequently drawn towards the
male pronucleus until the two abutted. Both pronuclei then increased in
size, the nucleoli moved around within the pronuclei and some nucleoli
coalesced. During pronuclear growth, the organelles contracted from the
cortex towards the centre of the oocyte, leaving a clear cortical zone. The
oocyte decreased in diameter from 112 to 106 microm (P < 0.0001) during
the course of the observation period. The female pronucleus was
significantly smaller in diameter than the male pronucleus (24.1 and 22.4
microm respectively, P = 0.008) and contained fewer nucleoli (4.2 and 7.0
respectively, P < 0.0001). After time-lapse recording, oocytes were
cultured for 48 h prior to embryo transfer or cryopreservation. Embryo
quality was related to fertilization events and periodicity of the
cytoplasmic wave, and it was found that good quality embryos arose from
oocytes that had more uniform timing from injection to pronuclear abuttal
and tended to have a longer cytoplasmic wave. In conclusion, we have shown
that time-lapse video cinematography is an excellent tool for studying
fertilization and early embryo development, and have demonstrated that
human fertilization comprises numerous complex dynamic events.
相似文献
13.
Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization 总被引:11,自引:0,他引:11
The development and application of fluorescence in-situ hybridization
(FISH) has opened the way for comprehensive studies on numerical chromosome
abnormalities in human spermatozoa. FISH can be rapidly applied to large
numbers of spermatozoa and thus overcomes the major limitation of
karyotyping spermatozoa after penetration of zona-free hamster oocytes. The
simultaneous hybridization of two or more chromosome-specific probes to
spermatozoa and subsequent detection of the bound probes using different
fluorescent detection systems enables two or more chromosomes to be
localized simultaneously in the same spermatozoon and provides a technique
for undertaking reasonable estimates of aneuploidy. The most commonly used
probes are those which bind to the centromeric region of specific
chromosomes. Most studies to date have concentrated on estimating
aneuploidy in spermatozoa from normospermic men, although reports are
beginning to appear on aneuploidy in spermatozoa from subfertile and
infertile men. Multi- probe FISH studies have generally reported disomy
(hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary
evidence that some chromosomes such as X, Y and 21 are predisposed towards
higher rates of non-disjunction during spermatogenesis. There are also
suggestions of inter-donor variability in aneuploidy frequencies for
specific chromosomes, although this requires confirmation in larger
studies. While FISH is clearly a powerful technique that has many
applications in reproductive medicine, it must also be realized that it
does have limitations and the technology itself is still evolving and has
yet to be fully validated on spermatozoa.
相似文献
14.
KA Hodgkinson SP Connors N Merner A Haywood T‐L Young WJ McKenna B Gallagher F Curtis AS Bassett PS Parfrey 《Clinical genetics》2013,83(4):321-331
To determine the phenotype and natural history of a founder genetic subtype of autosomal dominant arrhythmogenic right ventricular cardiomyopathy (ARVC) caused by a p.S358L mutation in TMEM43. The age of onset of cardiac symptoms, clinical events and test abnormalities were studied in 412 subjects (258 affected and 154 unaffected), all of which occurred in affected males significantly earlier and more often than unaffected males. Affected males were hospitalized four times more often than affected females (p ≤ 0.0001) and died younger (p ≤ 0.001). The temporal sequence from symptoms onset to death was prolonged in affected females by 1–2 decades. The most prevalent electrocardiogram (ECG) manifestation was poor R wave progression (PRWP), with affected males twice as likely to develop PRWP as affected females (p ≤ 0.05). Left ventricular enlargement (LVE) occurred in 43% of affected subjects, with 11% fulfilling criteria for dilated cardiomyopathy. Ventricular ectopy on Holter monitor was common and occurred early: the most diagnostically useful clinical test. No symptom or test could rule out diagnosis. This ARVC subtype is a sex‐influenced lethal arrhythmogenic cardiomyopathy, with a unique ECG finding, LV dilatation, heart failure and early death, where molecular pre‐symptomatic diagnosis has the greatest clinical utility. 相似文献
15.
SP Walker M Permezel SF Berkovic 《BJOG : an international journal of obstetrics and gynaecology》2009,116(6):758-767
While most women with epilepsy can expect a normal pregnancy outcome, epilepsy remains a significant contributor to both maternal and perinatal morbidity. Pre-pregnancy planning must address reliable contraception and optimisation of antiepileptic drug (AED) regimens to minimise teratogenic risk while maintaining seizure control. The most recent data from the AED registries regarding malformations is presented in this review, as is the limited data on the newer AEDs and studies linking neurocognitive outcomes to AED exposure. During pregnancy, important considerations include; therapeutic drug monitoring, surveillance for obstetric complications and vigilance for seizures during the intrapartum and postpartum period. 相似文献
16.
背景:阿德福韦双酯(ADV) 是一种有效治疗野生型和耐拉米夫定乙肝病毒(HBV)的核苷酸类药物。在使用核苷酸类药物治疗慢性乙肝时,当治疗时间为 48、96、144周时,耐ADV变异体出现的累积发生率分别为0、 0.8-3%和0-5.9%。目的:研究67例对拉米夫定耐药且接受ADV治疗的慢性乙肝患者耐ADV病毒变异体的表型和基因型特点。方法:HBV DNA含量采用实时定量PCR技术。ADV变异体检测采用基质辅助激光解吸电离/飞行时间质谱为基础的基因分型 相似文献
17.
18.
Treatment of allergic bronchopulmonary aspergillosis (ABPA) has remained both problematic as well as controversial. Although the sheet anchor in treatment of ABPA still remains steroids, various workers have tried oral antifungals (fluconazole and itraconazole) with encouraging results. This study evaluates the effect of fluconazole or itraconazole in the treatment of ABPA patients and compares them with the patients who had received palliative therapy other than antifungals. Case records of 44 proven cases of ABPA treated at our referral service hospital during February 1998 to April 2001 were analyzed. In addition to oral and inhaled bronchodilators, 16 patients received fluconazole 150 mg OD and 13 patients itraconazole 200 mg OD for six months. Response to therapy was assessed clinically, radiologically and by spirometry every 3 months. Patients who did not receive antifungals had chronic course characterized by airway obstruction, recurrent pulmonary consolidation and obstructive defect on pulmonary function test (PFT). Patients treated with itraconazole had better control of asthma symptoms, less requirement of reliever inhalers, steroids and lesser exacerbations of asthma during follow-up even after stopping antifungal. Fluconazole group had better control of symptoms but improvement in other parameters was not statistically significant. From this study it was evident that itraconazole improved the symptoms of airway obstruction, pulmonary functions, pulmonary opacities and decreased exacerbations during follow up.Key Words: Allergic bronchopulmonary aspergillosis, Fluconazole, Itraconazole 相似文献
19.
目的 建立一种快速、灵敏的高效液相色谱-串联质谱(HPLC-MS/MS)方法以测定人血浆中对乙酰氨基酚浓度,并应用于两种对乙酰氨基酚制剂的人体药代动力学和生物等效性研究。方法 以替硝唑为内标,200μL血浆样品经5倍于其体积的乙酸乙酯液液萃取,再经Waters XBridge? C18柱等度洗脱分离后导入串联质谱,以正离子多反应监测模式进行定量分析,对乙酰氨基酚和内标的选择性反应离子对分别是m/z 152→110和248→121。方法经验证后应用于19名健康受试者单剂量空腹口服两种对乙酰氨基酚制剂500mg后药代动力学和生物等效性的研究。结果 血浆中对乙酰氨基酚在0.1~8.0 μg·mL-1范围内线性良好(r2 > 0.99),最低检测限为 0.1 μg·mL-1,提取回收率为91.0%~98.7%,日内和日间准确度分别为98.8%~111.3% (精密度:CV ? 9.03%)和94.9%~102.6% (精密度:CV ? 10.68%)。生物等效性试验中,受试制剂与参比制剂的主要药代动力学参数Cmax、AUC0-t和AUC0-∞ 几何均值比的90%置信区间分别为83.50%~105.79%,94.25%~101.54%和93.24%~101.02%,均落在生物等效可接受标准80.00%~125.00%范围内。结论 所建立测定人血浆中对乙酰氨基酚浓度的HPLC-MS/MS法具有快速灵敏、回收率高、选择性好的特点,适用于对乙酰氨基酚片人体药代动力学和生物等效性研究。受试制剂与参比制剂在人体内吸收速度和程度相似,两种制剂生物等效。 相似文献
20.