全文获取类型
收费全文 | 1484篇 |
免费 | 375篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 40篇 |
妇产科学 | 202篇 |
基础医学 | 80篇 |
口腔科学 | 14篇 |
临床医学 | 725篇 |
内科学 | 206篇 |
皮肤病学 | 15篇 |
神经病学 | 94篇 |
特种医学 | 78篇 |
外国民族医学 | 1篇 |
外科学 | 103篇 |
综合类 | 24篇 |
预防医学 | 186篇 |
眼科学 | 3篇 |
药学 | 53篇 |
中国医学 | 1篇 |
肿瘤学 | 41篇 |
出版年
2021年 | 17篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 84篇 |
2017年 | 107篇 |
2016年 | 120篇 |
2015年 | 104篇 |
2014年 | 106篇 |
2013年 | 131篇 |
2012年 | 80篇 |
2011年 | 86篇 |
2010年 | 80篇 |
2009年 | 98篇 |
2008年 | 93篇 |
2007年 | 98篇 |
2006年 | 64篇 |
2005年 | 66篇 |
2004年 | 64篇 |
2003年 | 43篇 |
2002年 | 28篇 |
2001年 | 24篇 |
2000年 | 22篇 |
1999年 | 31篇 |
1998年 | 17篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1971年 | 5篇 |
1967年 | 9篇 |
排序方式: 共有1871条查询结果,搜索用时 0 毫秒
11.
J L Burgess D F Kovalchick K B Kyes J N Thompson S Barnhart 《International journal of occupational and environmental health》1999,5(3):194-197
Actual or perceived exposure to hazardous materials may result in physiologic and psychological effects. However, hyperventilation following such exposures has not previously been reported. After a large-scale industrial release of oxides of nitrogen, five (29%) of 17 patients evaluated at a major trauma center were hyperventilating, as defined by arterial PCO2 <33 mm Hg, and nine patients (53%) had arterial PCO2 <37 mm Hg. First responders (rescue team members and paramedics) had a higher rate of hyperventilation than other occupational groups. Age, gender, marital status, decontamination, and mode of arrival were not significantly associated with hyperventilation, although marital status approached significance. This study suggests that hyperventilation may be a common reaction after hazardous-materials incidents, and that certain populations may be at increased risk for this condition. 相似文献
12.
Multivariate random length data occur when we observe multiple measurements of a quantitative variable and the variable number of these measurements is also an observed outcome for each experimental unit. For example, for a patient with coronary artery disease, we may observe a number of lesions in that patient's coronary arteries, along with percentage of blockage of each lesion. Barnhart and Sampson first proposed the multiple population model to analyse multivariate random length data without covariates. This paper extends their approach to deal with multiple covariates. We propose a new multiple population regression model with covariates, and discuss the estimation issues. We analyse data from the TYPE II coronary intervention study to illustrate the methodology. 相似文献
13.
As we move into the 1990s, the challenges we face are many. Our ever-changing health care industry is giving managers, directors, and administrators much to ponder: how do we reduce costs and improve patient care? One promising area that may help answer this question in pharmacy services is bar code technology. This article offers helpful advice about the development of bar code and drug delivery systems and discusses the future applications of bar code technology in pharmacy practice, based on 3 years of hands-on experience at Florida Medical Center. 相似文献
14.
Neonatal mice 1 and 5 days of age and older mice 25 days of age were injected with an increasing dose of monosodium glutamate (MSG) for a ten-day period and observed for at least 150 days. Both male and female animals in the 1- and 5-day age group treated with MSG showed large increases in weight over controls along with a shortened body length. The MSG group also showed decreases in locomotor and explatory behavior. The 25-day animals took much longer to show effects or failed to show any effects, indicating that the MSG-induced changes studied are age dependent. Possible methodological considerations accounting for conflicting reports in the MSG literature are discussed in light of the present findings. 相似文献
15.
Dibenzo[a,l]pyrene-induced DNA adduction, tumorigenicity, and Ki-ras oncogene mutations in strain A/J mouse lung 总被引:1,自引:0,他引:1
Prahalad AK; Ross JA; Nelson GB; Roop BC; King LC; Nesnow S; Mass MJ 《Carcinogenesis》1997,18(10):1955-1963
Dibenzo[a,l]pyrene (DB[a,l]P), an environmental polycyclic aromatic
hydrocarbon, is the most potent carcinogen ever tested in mouse skin and
rat mammary gland. In this study, DB[a,l]P was examined for DNA adduction,
tumorigenicity, and induction of Ki-ras oncogene mutations in tumor DNA in
strain A/J mouse lung. Groups of mice received a single i.p. injection of
0.3, 1.5, 3.0, or 6.0 mg/kg DB[a,l]P in tricaprylin. Following treatment,
DNA adducts were measured at times between 1 and 28 days, while tumors were
counted at 250 days and analyzed for the occurrence of point mutations in
codons 12 and 61 of the Ki-ras oncogene. DB[a,l]P in strain A/J mouse lung
induced six major and four minor DNA adducts. Maximal levels of adduction
occurred between 5 and 10 days after injection followed by a gradual
decrease. DB[a,l]P-DNA adducts in lung tissue were derived from both anti-
and syn-11,12- dihydroxy-13,14-epoxy-
11,12,13,14-tetrahydrodibenzo[a,l]pyrene (DB[a,l]PDE) and both
deoxyadenosine (dAdo) and deoxyguanosine (dGuo) residues in DNA as revealed
by cochromatography. The major adduct was identified as a product of the
reaction of an anti-DB[a,l]PDE with dAdo in DNA. DB[a,l]P induced
significant numbers of lung adenomas in a dose- dependent manner, with the
highest dose (6.0 mg/kg) yielding 16.1 adenomas/mouse. In
tricaprylin-treated control animals, there were 0.67 adenomas/mouse. Based
on the administered dose, DB[a,l]P was more active than other environmental
carcinogens including benzo[a]pyrene. As a function of time-integrated DNA
adduct levels, DB[a,l]P induced lung adenomas with about the same potency
as other PAHs, suggesting that the adducts formed by DB[a,l]P are similar
in carcinogenic potency to other PAHs in the strain A/J mouse lung model.
Analysis of the Ki- ras mutation spectrum in DB[a,l]P-induced lung tumors
revealed the predominant mutations to be G-->T transversions in the
first base of codon 12, A-->G transitions in the second base of codon
12, and A-->T transversions in the second or third base of codon 61,
concordant with the DNA adduct profile.
相似文献
16.
17.
目的分析中国不同人群及不同胃部疾病病例来源的幽门螺杆菌致病相关基因cagA、iceA、vacA及HP0519的分布.方法采用特异引物聚合酶链式反应(PCR)方法分析150株幽门螺杆菌上述基因的多态性分布特点,并对其分布作初步统计分析.结果93%(139/150)中国菌株cagA基因3′端重复序列的PCR产物具有东方菌株特征.75%(113/150)菌株iceA基因为iceA1,19%(29/150)为iceA2,不同地区间iceA基因的分布差异无统计学意义.云南菌株iceA1、iceA2的分布与菌株分离个体的种族特点及临床疾病类型无显著关系.96%中国菌株(144/150)vacA基因s区的等位基因为s1;m区等位基因m2、m1b和m1b-m2的比例分别为57%(85/150)、27%(41/150)和11%(16/150),仅2株福建菌株为m1a.不同地区间vacA s1、m2、m1b分布的差异无统计学意义.云南菌株m1b-m2的分布高于福建和北京菌株.云南菌株vacA s区等位基因的多样性与分离个体的种族及临床疾病类型无显著关系.vacA m区等位基因的多样性与分离个体的临床疾病类型无显著关系,但不同民族间m2的分布有显著差异,白族人群m2的分布显著少于汉族和纳西族.93%(140/150)的中国菌株HP0519基因具有24 bp和15 bp DNA插入和缺失的多态性特点.不同地区间HP0519基因的多态性无显著不同.云南菌株HP0519的多态性与菌株分离个体的临床疾病类型无显著关系,但来源不同民族菌株的HP0519基因存在差异.结论幽门螺杆菌中国菌株cagA 3′端JF/TR特异引物的扩增结果具有东亚菌株特点.中国菌株vacA基因多为s1,其分布与菌株分离个体的临床疾病类型无关.中国菌株vacA基因m区的分布具有多样性.中国菌株HP0519基因具有24 bp和15 bp插入和缺失的多态性特点. 相似文献
18.
Barnhart KT Rinaudo P Hummel A Pena J Sammel MD Chittams J 《Fertility and sterility》2003,80(6):1345-1351
OBJECTIVE: The diagnosis of ectopic pregnancy (EP) is often confirmed at presentation (acute), but often requires serial beta-hCG levels to confirm the diagnosis (chronic). The purpose of this study is to analyze whether these clinical presentations represent a spectrum of disease. DESIGN: The retrospective cohort study of 452 patients diagnosed with EP at the University of Pennsylvania in the years 1990-1999. SETTING: University of Pennsylvania, Philadelphia, Pennsylvania. PATIENT(S): Four hundred fifty-two patients diagnosed with EP. Patients diagnosed with EP were divided into two groups according to the time of diagnosis. MAIN OUTCOME MEASURE(S): A total of 37 parameters were examined including historic and demographic factors, findings at presentation, and treatment and outcome variables. RESULT(S): The two groups were similar in terms of historic EP risk factors. Multivariable analysis demonstrates that women with a chronic presentation were less likely to have received fertility medications (odds ratio [OR] 0.23; 95% confidence interval [CI] 0.06-0.84), less likely to present with pain (OR 0.29; 95% CI 0.12-0.71), have a lower beta-hCG level at presentation (9,849 mIU/mL +/- 16,726 vs. 1,787 mIU/mL +/- 4,717), lower chance of rupture (OR 0.19; 95% CI 0.05-0.73), and less frequently have blood type 0. CONCLUSION(S): Women diagnosed with ectopic pregnancy can be categorized into two groups, those with an acute presentation and those with a chronic presentation. Differences in risk factors, presentation, and outcome may reflect differences in trophoblast viability or invasive potential. 相似文献
19.
20.
Utility of screening for other causes of infertility in women with "known" polycystic ovary syndrome
McGovern PG Legro RS Myers ER Barnhart HX Carson SA Diamond MP Carr BR Schlaff WD Coutifaris C Steinkampf MP Nestler JE Gosman G Leppert PC Giudice LC;National Institutes for Child Health Human Development-Reproductive Medicine Network 《Fertility and sterility》2007,87(2):442-444
We investigated the prevalence of abnormal screening results (questionnaire and testing for other causes of oligo-ovulation, male or tubal factor infertility) in a group of 1,313 oligo-ovulatory women (included and excluded subjects) whose condition was screened for inclusion in the Pregnancy in Polycystic Ovary Syndrome trial, a multicenter clinical trial that was conducted at 13 sites in the United States. Other than failure to demonstrate laboratory evidence of hyperandrogenemia, the most common reasons for subject exclusion were persistent oligospermia and tubal factor infertility. 相似文献