全文获取类型
收费全文 | 14990篇 |
免费 | 1401篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 124篇 |
儿科学 | 624篇 |
妇产科学 | 296篇 |
基础医学 | 1865篇 |
口腔科学 | 353篇 |
临床医学 | 1645篇 |
内科学 | 2879篇 |
皮肤病学 | 191篇 |
神经病学 | 1363篇 |
特种医学 | 716篇 |
外科学 | 2171篇 |
综合类 | 376篇 |
一般理论 | 18篇 |
预防医学 | 1435篇 |
眼科学 | 402篇 |
药学 | 1090篇 |
中国医学 | 12篇 |
肿瘤学 | 891篇 |
出版年
2022年 | 141篇 |
2021年 | 244篇 |
2020年 | 158篇 |
2019年 | 252篇 |
2018年 | 340篇 |
2017年 | 267篇 |
2016年 | 281篇 |
2015年 | 344篇 |
2014年 | 442篇 |
2013年 | 619篇 |
2012年 | 837篇 |
2011年 | 813篇 |
2010年 | 505篇 |
2009年 | 450篇 |
2008年 | 718篇 |
2007年 | 751篇 |
2006年 | 742篇 |
2005年 | 681篇 |
2004年 | 714篇 |
2003年 | 577篇 |
2002年 | 606篇 |
2001年 | 372篇 |
2000年 | 350篇 |
1999年 | 336篇 |
1998年 | 261篇 |
1997年 | 220篇 |
1996年 | 233篇 |
1995年 | 158篇 |
1994年 | 192篇 |
1993年 | 166篇 |
1992年 | 295篇 |
1991年 | 262篇 |
1990年 | 216篇 |
1989年 | 224篇 |
1988年 | 213篇 |
1987年 | 209篇 |
1986年 | 197篇 |
1985年 | 178篇 |
1984年 | 131篇 |
1983年 | 106篇 |
1982年 | 100篇 |
1981年 | 94篇 |
1980年 | 108篇 |
1979年 | 90篇 |
1978年 | 87篇 |
1977年 | 85篇 |
1976年 | 99篇 |
1974年 | 75篇 |
1973年 | 95篇 |
1972年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
Grant P 《Contemporary pediatrics》1994,11(11):84-6, 89-90, 93
Want to practice better medicine, insure third-party reimbursement, and help educate residents in primary care? A standardized encounter form can do all this, and more. Here's how. 相似文献
145.
146.
147.
Grant EG Duerinckx AJ El Saden S Melany ML Hathout G Zimmerman P Cohen SN Singh R Baker JD 《AJR. American journal of roentgenology》1999,172(4):1123-1129
OBJECTIVE: A wide range of Doppler threshold values for carotid stenosis is found in the literature. We undertook this study to compare methods of derivation and to determine if an optimum strategy of threshold selection exists for a high-risk population. MATERIALS AND METHODS: From the sonograms of all patent internal carotid arteries, peak systolic velocity in the internal carotid artery (ICA(PSV)) and the ratio of peak systolic velocity in the internal carotid artery to that of the common carotid artery (ICA(PSV)/ CCA(PSV)) were compared with the percentage of angiographically determined stenosis. Receiver operating characteristic curves were generated for levels of stenosis > or =60% and > or =70%. Doppler thresholds were chosen on the basis of maximum accuracy and on the basis of > or =90% sensitivity and specificity. Patients were then segregated into symptomatic and asymptomatic cohorts, and the above process was repeated. An effectiveness analysis was also conducted using various Doppler thresholds. Thresholds derived using these three methods were compared and optimal values chosen. RESULTS. Of 333 carotid arteries that fit inclusion criteria, 132 were found in asymptomatic patients and 201 in symptomatic patients. Maximum accuracy, > or =90% sensitivity and specificity, and effectiveness analysis each produced different ranges of thresholds. We chose final thresholds that maintained patient outcome profiles. For asymptomatic patients at the > or =60% stenosis level, thresholds were ICA(PSV) = 200 cm/sec and ICA(PSV)/CCA(PSV) = 3.0. For symptomatic patients with stenosis > or =70%, thresholds were ICA(PSV) = 175 cm/sec and ICA(PSV)/CCA(PSV) = 2.5. CONCLUSION: Considerable latitude exists in the choice of carotid Doppler thresholds. We propose a rational strategy for threshold selection based on a combination of three commonly used methods. Our observations indicate that it appears advisable to consider symptomatic and asymptomatic patients separately and to apply appropriately derived thresholds. 相似文献
148.
Activated blood coagulation factor XIII has an important role in the final stage of the clotting cascade by the covalent crosslinking of alpha- and gamma-fibrin chains. We have recently shown that a functional polymorphism in exon 2. codon 34 of the FXIII A-subunit gene is protective against myocardial infarction. To investigate the prevalence of three other common point mutations in the A-subunit gene (codon 564, C to T, 650 G to A and 651 G to C) and their association with FXIII activity and antigen levels, 275 patients with coronary artery disease and 196 controls were studied. There was no difference in the prevalence of the polymorphisms between patients and controls or between patients with or without MI. Only genotype at codon 564 was associated with FXIII activity with lower activities in subjects possessing the T allele. There was evidence of linkage disequilibrium between codon 34 and codon 564. These results suggest that FXIIIVal34Leu is the only common polymorphism in the coding region of the A-subunit gene of FXIII associated with coronary artery disease. 相似文献
149.
Carter AM Catto AJ Bamford JM Grant PJ 《Stroke; a journal of cerebral circulation》1999,30(12):2606-2611
BACKGROUND AND PURPOSE: The role of polymorphisms of the platelet glycoprotein (GP) IIb/IIIa receptor in the development of cardiovascular disease has been the subject of intensive research. The aim of this study was to determine the association of the HPA-3 polymorphism of platelet GPIIb with ischemic stroke and subsequent survival and to identify possible interactions of HPA-3 with classic risk factors. METHODS: HPA-3 genotype was determined by restriction fragment length polymorphism in 515 patients with ischemic stroke and 423 healthy, age-matched control subjects. RESULTS: There was no significant difference in the genotype distribution of patients and controls, nor was there any difference when patients were subclassified into small- and large-vessel disease. The genotype distribution of the 231 patients subsequently dying during 2.8 years of follow-up (aa=45.0%, ab=46.8%, bb=8.2%) was significantly different from that of those still alive (aa=37.0%, ab=48.2%, bb=14. 8%) (P=0.03). In a Cox regression model, the relative risks for poststroke mortality in patients of aa and ab genotype compared with those of bb genotype were 2.42 (95% CI, 1.24 to 4.71) and 2.13 (95% CI, 1.09 to 4.17), respectively, after we accounted for confounding factors. In addition, significant interactions of HPA-3 with the Pl(A) polymorphism of GPIIIa (P=0.002) and with fibrinogen (P=0.01) were identified in relation to mortality. CONCLUSIONS: HPA-3 is related to poststroke mortality, and the significant interaction of HPA-3 with Pl(A) and fibrinogen suggests that it may in some way influence the interaction of GPIIb/IIIa with fibrinogen, particularly in the presence of high fibrinogen. 相似文献
150.
OBJECTIVE: Prior research in a community sample indicated that almost half the individuals receiving a diagnosis of DSM-IV alcohol abuse did so on the basis of only one symptom, driving after drinking too much. While this is certainly unwise behavior, it may not be a psychiatric disorder. Therefore, we investigated the differential validity of this subgroup of abuse cases by testing the association of a set of external validating criterion variables with three groups: those who met criteria for abuse just for drinking-driving, those who met criteria by other means and those with no alcohol diagnosis. Present status of past cases of abuse was also investigated. METHOD: Subjects were 22,204 U.S. household residents (a subset of a national probability sample) interviewed in 1992 with the Alcohol Use Disorders and Associated Disabilities Interview Schedule. The generalized logit model was the principal means of analysis. RESULTS: Subjects who met criteria for DSM-IV alcohol abuse just for drinking-driving differed from subjects with no diagnosis on about half the variables tested, while those who met criteria for abuse in other ways differed from subjects with no diagnosis on all variables tested. The two abuse groups differed from each other on some but not all variables. Past cases of abuse for drinking-driving and past cases of other abuse were equally likely to have remitted in the last 12 months, and slightly less likely to meet criteria for current dependence. CONCLUSIONS: Further conceptual and empirical work is needed to resolve the difficulties with the DSM-IV alcohol abuse category. 相似文献