全文获取类型
收费全文 | 351篇 |
免费 | 28篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 18篇 |
妇产科学 | 6篇 |
基础医学 | 41篇 |
口腔科学 | 9篇 |
临床医学 | 40篇 |
内科学 | 91篇 |
皮肤病学 | 30篇 |
神经病学 | 9篇 |
特种医学 | 68篇 |
外科学 | 13篇 |
综合类 | 17篇 |
预防医学 | 6篇 |
药学 | 37篇 |
肿瘤学 | 16篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 11篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 11篇 |
2009年 | 17篇 |
2008年 | 11篇 |
2007年 | 20篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 21篇 |
1997年 | 15篇 |
1996年 | 28篇 |
1995年 | 8篇 |
1994年 | 18篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 16篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有402条查询结果,搜索用时 24 毫秒
101.
102.
Fergus Scott FRACOG DDU Danielle Wheeler BSc Michael Sinosich MSc PhD Antheunis Boogert FRACOG DDU COGU John Anderson FRCOG FRACOG DDU COGU David Edelman SB SM Mphil PhD 《The Australian & New Zealand journal of obstetrics & gynaecology》1996,36(4):381-384
Summary: Screening for aneuploidy using maternal age has a low detection rate and high false positive rate. Second trimester maternal serum screening increases trisomy 21 detection and decreases die false positive rate. First trimester screening would enable definitive diagnosis with chorionic villus sampling, and simple surgical termination of affected pregnancies would still be an option. Nuchal translucency (NT), free beta human chorionic gonadotrophin (fβHCG) and maternal age were assessed in 302 patients before chorionic villus sampling. NT positively and fβHCG negatively correlated with gestation, but neither correlated with maternal age nor with each other. Both NT and fβHCG were increased in trisomy 21. NT was increased and fβHCG was decreased in trisomy 18. Multivariate discriminant analysis enabled 87.5% detection of trisomy 21 in this high-risk population, for a 14% false positive rate. In a simulated normal population, using a risk cut-off of 1 in 250, 71% detection was achieved for a 7% false positive rate. The combination of NT, fβHCG and maternal age is a simple, readily available and viable first trimester screening strategy. 相似文献
103.
ML Katcher P Agran D Laraque SH Pollack GA Smith HR Spivak M Tenenbein SB Tully 《Pediatrics》1999,103(2):524-526
Proper record-keeping of emergency department visits and hospitalizations of injured children is vital for appropriate patient management. Determination and documentation of the circumstances surrounding the injury event are essential. This information not only is the basis for preventive counseling, but also provides clues about how similar injuries in other youth can be avoided. The hospital records have an important secondary purpose; namely, if sufficient information about the cause and mechanism of injury is documented, it can be subsequently coded, electronically compiled, and retrieved later to provide an epidemiologic profile of the injury, the first step in prevention at the population level. To be of greatest use, hospital records should indicate the "who, what, when, where, why, and how" of the injury occurrence and whether protective equipment (eg, a seat belt) was used. The pediatrician has two important roles in this area: to document fully the injury event and to advocate the use of standardized external cause-of-injury codes, which allow such data to be compiled and analyzed. 相似文献
104.
Vakhitova IuV Salimgareeva MKh Sibiriak SV Kurchatova NN Seredin SB 《Eksperimental'naia i klinicheskaia farmakologiia》2004,67(5):34-38
The effects of ladasten on the activation-induced expression of Fas-receptor on T-lymphocytes, their sensitivity to Fas-induced apoptosis, and the expression of mitogen-activated ERKI/ERK2 protein kinases have been studied. In the range of concentrations 0.1-10 microM, ladasten exhibited a comitogenic effect on the TCR-mediated stimulation of T-lymhocytes ion the peripheral human blood, which was accompanied by an increase in the level of phosphorylated form of ERK-2. At the same time, ladasten virtually did not change the activation-induced expression of Fas-receptor on T-lymphocytes, but reduced the rate of the Fas-induced apoptosis. It was concluded that the immunoprotective effect of ladasten is probably based on a decrease in the rate of Fas-induced apoptosis. 相似文献
105.
Glauce SB Viana Carolina C Ana Medeiros Michelle R Ana Lacerda Kalyne AM L Leal Tiago G Vale F José deAbreu Matos 《BMC pharmacology》2004,4(1):1-7
Background
Psoriasis is a chronic inflammatory skin disease that can be successfully treated with a mixture of fumaric acid esters (FAE) formulated as enteric-coated tablets for oral use. These tablets consist of dimethylfumarate (DMF) and salts of monoethylfumarate (MEF) and its main bioactive metabolite is monomethylfumarate (MMF). Little is known about the pharmacokinetics of these FAE. The aim of the present study was to investigate the hydrolysis of DMF to MMF and the stability of MMF, DMF and MEF at in vitro conditions representing different body compartments.Results
DMF is hydrolyzed to MMF in an alkaline environment (pH 8), but not in an acidic environment (pH 1). In these conditions MMF and MEF remained intact during the period of analysis (6 h). Interestingly, DMF was hardly hydrolyzed to MMF in a buffer of pH 7.4, but was rapidly hydrolyzed in human serum having the same pH. Moreover, in whole blood the half-life of DMF was dramatically reduced as compared to serum. The concentrations of MMF and MEF in serum and whole blood decreased with increasing time. These data indicate that the majority of the FAE in the circulation are metabolized by one or more types of blood cells. Additional experiments with purified blood cell fractions resuspended in phosphate buffered saline (pH 7.4) revealed that at concentrations present in whole blood monocytes/lymphocytes, but not granulocytes and erythrocytes, effectively hydrolyzed DMF to MMF. Furthermore, in agreement with the data obtained with the pure components of the tablet, the enteric-coated tablet remained intact at pH 1, but rapidly dissolved at pH 8.Conclusion
Together, these in vitro data indicate that hydrolysis of DMF to MMF rapidly occurs at pH 8, resembling that within the small intestines, but not at pH 1 resembling the pH in the stomach. At both pHs MMF and MEF remained intact. These data explain the observation that after oral FAE intake MMF and MEF, but not DMF, can be readily detected in the circulation of human healthy volunteers and psoriasis patients. 相似文献106.
1病例报告患者,男,22岁,因间歇性全身乏力、肌肉酸痛2 wk,发冷1 wk,发热4 d入院.曾在我院查WBC 4.5×109/L,N 0.60,L 0.4,体温波动在38~40℃.初步诊断"上呼吸道感染",用阿莫西林、VC银翘片、清热解毒冲剂等治疗无效.查体:T 38.9℃,BP面性12/8 kPa.全身皮肤无出血点,双眼球结膜轻度充血,咽部充血,软腭未见充血点,心肺腹部未见阳性体征.实验室检查:WBC 7.85 × 109/L,N 0.79,L 0.21,HGB 150g/L,PCL30×109/L,尿蛋白3.2g/L,流行性出血热抗体( ).诊断:流行性出血热.入院后立即按照流行性出血热的治疗原则给予抗病毒、抗渗出、抗出血治疗.具体包括卧床休息,给予高热量,多维生素,易消化饮食;维持水、电解质、酸碱及血浆渗透压平衡;给予大剂量(5 g)Vit.C和Vit.E.同时给予氢化可地松100 mg/d,稀释后缓慢静脉滴注.入院后3 d患者的尿量由450 mL/d增至750 mL/d,肌酐204.6μmol/L,BUN 13.3 mmol/L.5 d尿量增加至4000 mL/d.经综合治疗10 d,肌酐和BUN检查等正常,痊愈出院,随访1 mo未见异常. 相似文献
107.
The lymphocyte Hprt gene has been used extensively as a reporter locus to
monitor the mutational effects of the exposure of animals to genotoxicants.
Implicit in this view of the function of a reporter gene is the assumption
that its mutagenic response is representative of that of other genes in the
organism. As a test of this hypothesis we compared the frequency of
6-thioguanine-resistant (TGr) mutants at the Hprt locus with the mutant
frequency (MF) induced at another locus, the ouabain resistance (Oua)
locus. The frequency of spontaneous OUA(R) mutants was estimated to be
1.1x10(-7) (MF between <0.3 and 1.1x10(- 7)), which was approximately
30-fold less than the spontaneous TGr MF. Following treatment with
N-ethyl-N-nitrosourea (ENU), the induced OUA(R) MF at each of two dose
levels (50 and 150 mg/kg ENU) and two time points (3 and 6 weeks
post-exposure) was consistently 8- to 9-fold lower than the corresponding
TGr MF. Thus the mutagenic response of the Oua locus closely paralleled
that of the Hprt locus, indicating a similarity in their response to ENU.
In addition, the Oua locus was 3-4 times more sensitive than the Hprt locus
to the mutagenic effect of ENU, as measured by the fold increase in MF over
the background level. The number of ENU-mutable sites capable of resulting
in a TGr or OUA(R) phenotype, otherwise known as the mutation target size,
was estimated to differ by an order of magnitude between the two loci. This
difference in target size correlates with, and therefore may largely
account for, the difference in induced MF between both loci.
相似文献
108.
Verghis SB; Essigmann JM; Kadlubar FF; Morningstar ML; Lasko DD 《Carcinogenesis》1997,18(12):2403-2414
Mutagenesis by the human bladder carcinogen 4-aminobiphenyl (ABP) was
studied in single-stranded DNA from a bacteriophage M13 cloning vector. In
comparison to ABP lesions in double-stranded DNA, lesions in single-
stranded DNA were approximately 70-fold more mutagenic and 50-fold more
genotoxic. Sequencing analysis of ABP-induced mutations in the lacZ gene
revealed exclusively base-pair substitutions, with over 80% of the
mutations occurring at G sites; the G at position 6310 accounted for 25% of
the observed mutations. Among the sequence changes at G sites, G- ->T
transversions predominated, followed by G-->C transversions and G--
>A transitions. In order to further elucidate the mutagenic mechanism of
ABP, an oligonucleotide containing the major DNA adduct, N-
(deoxyguanosin-8-yl)-4-aminobiphenyl (dG(8-ABP)), was situated within the
PstI site of a single-stranded M13 genome. After in vivo replication of the
adduct containing ABP-modified and control (unadducted) genomes, the
mutational frequency and mutational specificity of the dG(8-ABP) lesion
were determined. The targeted mutational efficiency was approximately
0.01%, and the primary mutation observed was the G-->C transversion.
Thus dG(8-ABP), albeit weakly mutagenic at the PstI site, can contribute to
the mutational spectrum of ABP lesions.
相似文献
109.
The predictive value of the zona-free hamster egg penetration test in relation to in-vitro fertilization at various insemination concentrations 总被引:2,自引:0,他引:2
Zainul Rashid MR; Fishel SB; Thornton S; Hall JA; Ndukwe G; Aloum M; Fleming SD 《Human reproduction (Oxford, England)》1998,13(3):624-629
The aim of the study was to evaluate the predictive value of the zona- free
hamster egg penetration test (ZHEPT) for success in in-vitro fertilization
(IVF) at various insemination concentrations ranging between 0.1 and
>0.6 x 10(6)/ml. The ZHEPT was assessed using sperm samples from 87
couples undergoing IVF treatment. A similar test was simultaneously
performed on the same semen sample following ionophore induction of the
acrosome reaction (ZHEPTii test). Both the tests were poorly correlated
with the fertilization rate of IVF at all the insemination concentrations
except at >0.6 x 10(6)/ml, when there was good correlation between the
ZHEPTii test and the fertilization rate. Following exclusion of two cases
with an oocyte problem, further statistical analysis revealed that both the
ZHEPT and ZHEPTii tests were poorly correlated with fertilization rate in
IVF in this treatment group. This study suggests that the ZHEPT (with and
without ionophore induction of the acrosome reaction) has a poor predictive
value for the success of fertilization in IVF treatment at any insemination
concentration.
相似文献
110.
SB Vestey C Sen CJ Calder CM Perks M Pignatelli ZE Winters 《Breast cancer research : BCR》2004,6(5):R571