全文获取类型
收费全文 | 103288篇 |
免费 | 8940篇 |
国内免费 | 539篇 |
专业分类
耳鼻咽喉 | 1399篇 |
儿科学 | 2475篇 |
妇产科学 | 1586篇 |
基础医学 | 12540篇 |
口腔科学 | 2353篇 |
临床医学 | 10616篇 |
内科学 | 23180篇 |
皮肤病学 | 1940篇 |
神经病学 | 9862篇 |
特种医学 | 4137篇 |
外国民族医学 | 1篇 |
外科学 | 18149篇 |
综合类 | 838篇 |
一般理论 | 194篇 |
预防医学 | 7148篇 |
眼科学 | 2362篇 |
药学 | 5940篇 |
中国医学 | 140篇 |
肿瘤学 | 7907篇 |
出版年
2024年 | 169篇 |
2023年 | 1506篇 |
2022年 | 1566篇 |
2021年 | 3524篇 |
2020年 | 2182篇 |
2019年 | 2975篇 |
2018年 | 3934篇 |
2017年 | 3039篇 |
2016年 | 3141篇 |
2015年 | 3401篇 |
2014年 | 4682篇 |
2013年 | 5701篇 |
2012年 | 7935篇 |
2011年 | 8013篇 |
2010年 | 4726篇 |
2009年 | 4315篇 |
2008年 | 6600篇 |
2007年 | 6250篇 |
2006年 | 6108篇 |
2005年 | 5951篇 |
2004年 | 5348篇 |
2003年 | 4894篇 |
2002年 | 4402篇 |
2001年 | 727篇 |
2000年 | 546篇 |
1999年 | 764篇 |
1998年 | 979篇 |
1997年 | 799篇 |
1996年 | 629篇 |
1995年 | 629篇 |
1994年 | 490篇 |
1993年 | 492篇 |
1992年 | 411篇 |
1991年 | 371篇 |
1990年 | 328篇 |
1989年 | 315篇 |
1988年 | 328篇 |
1987年 | 287篇 |
1986年 | 312篇 |
1985年 | 312篇 |
1984年 | 364篇 |
1983年 | 320篇 |
1982年 | 354篇 |
1981年 | 355篇 |
1980年 | 274篇 |
1979年 | 162篇 |
1978年 | 208篇 |
1977年 | 189篇 |
1975年 | 141篇 |
1974年 | 145篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
71.
72.
BACKGROUND: Studies have shown that alcoholics have smaller brain volumes than non-alcoholic cohorts, but an effect of family history (FH) of heavy drinking on brain volume has not been demonstrated. We examined the relationship between an FH of heavy drinking and both brain shrinkage as measured by the ratio of brain volumes to intracranial volume (ICV) as well as maximal brain growth as measured by ICV in early-onset and late-onset alcoholics. METHODS: With T1-weighted resonance imaging, we measured ICV, brain volume, and white and gray matter volume in adult treatment-seeking late-onset and early-onset alcoholics with either a positive or a negative FH of heavy alcohol use, and in healthy control subjects. We also calculated brain shrinkage using a ratio of soft tissue volumes to ICV. RESULTS: The FH positive alcoholic patients had significantly smaller ICVs than FH negative patients, suggesting smaller premorbid brain growth. Brain shrinkage did not correlate with FH. Late-onset alcoholics showed a greater difference in ICV between FH positive and FH negative patients than early-onset alcoholics. Late-onset FH positive patients also had significantly lower IQ scores than late-onset FH negative patients, and IQ scores were correlated with ICV. CONCLUSIONS: These data provide evidence that parental alcohol use might increase risk for alcoholism in offspring in part by a genetic and/or environmental effect that might be related to reduced brain growth. 相似文献
73.
Ventilation imaging of the lung: Comparison of hyperpolarized helium-3 MR imaging with Xe-133 scintigraphy 总被引:1,自引:0,他引:1
Talissa A. Altes MD Patrice K. Rehm MD Frank Harrell PhD Michael Salerno PhD Thomas M. Daniel MD Eduard E. de Lange MD 《Academic radiology》2004,11(7):729-734
RATIONALE AND OBJECTIVES: To compare hyperpolarized helium-3 (HHe) magnetic resonance imaging (MRI) of the lung with standard Xe-133 lung ventilation scintigraphy. MATERIALS AND METHODS: We performed a retrospective review of 15 subjects who underwent HHe MRI and Xe-133 lung ventilation imaging. Coronal MRI sections were acquired after a single inhalation of HHe gas, and standard posterior planar lung ventilation scintigraphy was performed during continuous breathing of Xe-133 gas. The first breath scintigram of each patient was compared with a composite MR image composed of the sum of the individual MR images and with the individual helium-3 MR images. Ventilation defects on the two imaging modalities were compared for size, conspicuity, and concordance in presence and location. Assessment was done separately for each of four lung quadrants. RESULTS: Comparing the composite HHe MR images with Xe-133 scintigraphy, ventilation defect size, conspicuity and concordance were the same in 67% (40/60), 63% (38/60), and 62% (37/60) quadrants, respectively. Comparing the individual HHe MR image sections with the Xe-133 ventilation scan, there was concordance between the ventilation defects in 27% (16/60) of quadrants. More defects were identified on the individual HHe MR images in 62% (37/60) of quadrants. CONCLUSION: There was good agreement between composite HHe MR image and first breath Xe-133 scintigraphic images, supporting the widely held assumption that HHe MRI likely depicts first breath lung ventilation. 相似文献
74.
Osteochondral Fracture of the Fourth Metatarsal Head Treated by Open Reduction and Internal Fixation
Praveen K.R. Mereddy MBBS MSOrth DNB Orth MRCSEd Andrew Molloy MBchB MRCS FRCS Michael S. Hennessy BSc MBchB FRCSEd 《The Journal of foot and ankle surgery》2007,46(4):320-322
Fracture of the metatarsal head is uncommon, and reports of isolated osteochondral fracture of the metatarsal head are rare. Because of the distal location of the fracture, it is difficult to achieve and maintain reduction, and potential complications include avascular necrosis and subchondral fatigue fracture. The authors present a case of an osteochondral fracture in a 40-year-old man, which was treated by open reduction and internal fixation with a single twist-off screw, with good results 12 months postoperatively. 相似文献
75.
Isabelle Durieu Evelyne Vericel Daniel Guichardant Hubert Roth Jean-Paul Steghens Jocelyne Drai Raphaele Nove Josserand Eric Fontaine Michel Lagarde Gabriel Bellon 《Journal of cystic fibrosis》2007,6(5):320-326
BACKGROUND: An imbalance in the ratio of arachidonic acid and docosahexaenoic acid (DHA) was found in cystic fibrosis (CF) affected tissues and was suggested to promote inflammation. Several studies have shown that the long chain n-3 fatty acids reduced inflammatory activity while others have highlighted prooxidant activity of DHA at high concentrations. The aim of our study was to evaluate the effects of an intravenous fish-oil emulsion enriched with n-3 FA in patients with CF on plasma and platelet FA composition and peroxidation markers. METHODS: 13 patients with CF received one IV emulsion per week of 2 mL/kg fish-oil n-3 emulsion for 12 weeks. RESULTS: There was a significant increase in 20:5 n-3 and 22:6 n-3 platelet FA composition, no variation in 20:4 n-6, a decrease in n-9. There was no variation in plasma FA composition. Specific urinary markers of lipid peroxidation derived from n-3 and n-6 showed a very high level before infusion compared with usual values in healthy subjects which was not affected by treatment. A significant weight loss and a decrease in reduced glutathione were observed in adult patients. CONCLUSIONS: The intravenous administration of n-3 FA in CF patients induced a significant modification in platelet FA composition but no modification of oxidative markers. However, the weight loss and the decreased level in reduced glutathione observed in adult patients may suggest a potential deleterious activity for some patients. Further studies are necessary to determine the optimal dose and route for long chain FA administration required to reach a potential beneficial effect. 相似文献
76.
77.
This study of interprofessional work relations in a Canadian mental health team examines how nursing deployed different forms of power in order to alter the mental health division of labour, to gain administrative, organizational and content control over its own work, expand its jurisdictional boundaries by expropriating the work of other professionals, and exclude others from encroaching on its old and newly acquired jurisdictions. This is set against the context of nursing's long-standing professional project to consolidate and expand its professional jurisdiction. Using an ethnographic study of a single interprofessional mental health team in a psychiatric hospital in Canada, the paper attempts to understand the politics and paradoxes involved in realizing nursing's professional project and how the politics of professional autonomy and professional dominance are actually conducted through micro-political struggles. The data demonstrates the effects of the political struggles at the organizational and work process levels, particularly in the forms of collaboration that result. Nurses gained substantial autonomy from medical domination and secured practical dominion over the work of non-medical professionals. New forms of interprofessional collaboration were accomplished through both simultaneous and sequential micro-political struggles with psychiatrists and non-medical professionals, and the formation of political alliances and informal agreements. Nursing solidarity at the elite level and substantial effort by the elite nurses and their committed colleagues to mobilize their less enthused members were fundamental to their success. The nurses deployed political (power) strategies and tactics to organize and reorganize themselves and other professionals on multiple levels (politically, organizationally, ideologically, socially and culturally). This study reveals the complexity and robustness of micro-political dynamics in the constitution of professional and collaborative interprofessional work relations. 相似文献
78.
Conclusion We would like to stress that we do not necessarily consider AC for SPECT MPI to be unfeasible or unworthy of scientific pursuit;
indeed, a great deal of creative scientific effort has been poured into this area of investigation over the past 3 decades,
and much of it has contributed to a better understanding of the physics, as well as the clinical aspects, of our field. However,
the great variety of available AC hardware and software “flavors,” the historical pattern of commercial release of insufficiently
validated AC implementations, and the increasingly clouded health care reimbursement horizon may have created an environment
where the envisioned users of the technology have been desensitized and discouraged from expecting it to ever come to fruition
in a standardized, validated, and costeffective form.
It has been reported as recently as 2005 that the “entire base of SPECT cameras has only 5% of systems with attenuation correction.”8
Perhaps the reports of AC’s demise are exaggerated, but it certainly seems as if the people have spoken and, after readying
themselves for the wolf one too many times, have come to the conclusion that “the future (of AC) ain’t what it used to be”
. . .at least not yet. 相似文献
79.
80.
Amit Dang MBBS Gaurav Garg Padmanabh V. Rataboli MD 《The International journal of eating disorders》2009,42(4):385-386
Nocturnal Sleep‐Related Eating Disorder (NSRED) is a well‐documented sleeping disorder where the person is reported to experience bizarre eating behavior during sleep. Although various causes are implicated in this disorder, role of drugs cannot be ruled out. Here we narrate an interesting rare case report of a drug‐induced new onset NSRED, where a 45‐year‐old man on zolipdem performed an unexpected and bizarre eating behavior during somnambulistic state, type of which has not been reported earlier in the literature. The case falls under even rarer category as such behavior in sleep is reported mainly in woman. © 2008 by Wiley Periodicals, Inc. Int J Eat Disord 2009 相似文献