全文获取类型
收费全文 | 82149篇 |
免费 | 6387篇 |
国内免费 | 259篇 |
专业分类
耳鼻咽喉 | 938篇 |
儿科学 | 2187篇 |
妇产科学 | 1135篇 |
基础医学 | 11269篇 |
口腔科学 | 871篇 |
临床医学 | 8720篇 |
内科学 | 17594篇 |
皮肤病学 | 929篇 |
神经病学 | 8021篇 |
特种医学 | 3202篇 |
外科学 | 13159篇 |
综合类 | 929篇 |
一般理论 | 91篇 |
预防医学 | 6186篇 |
眼科学 | 2049篇 |
药学 | 5640篇 |
中国医学 | 96篇 |
肿瘤学 | 5779篇 |
出版年
2023年 | 677篇 |
2022年 | 1057篇 |
2021年 | 2456篇 |
2020年 | 1384篇 |
2019年 | 2244篇 |
2018年 | 2568篇 |
2017年 | 1836篇 |
2016年 | 1921篇 |
2015年 | 2268篇 |
2014年 | 3262篇 |
2013年 | 4170篇 |
2012年 | 6625篇 |
2011年 | 6877篇 |
2010年 | 3767篇 |
2009年 | 3299篇 |
2008年 | 5544篇 |
2007年 | 5727篇 |
2006年 | 5297篇 |
2005年 | 5251篇 |
2004年 | 4754篇 |
2003年 | 4349篇 |
2002年 | 3948篇 |
2001年 | 700篇 |
2000年 | 504篇 |
1999年 | 674篇 |
1998年 | 835篇 |
1997年 | 620篇 |
1996年 | 508篇 |
1995年 | 456篇 |
1994年 | 442篇 |
1993年 | 433篇 |
1992年 | 333篇 |
1991年 | 269篇 |
1990年 | 250篇 |
1989年 | 228篇 |
1988年 | 212篇 |
1987年 | 191篇 |
1986年 | 177篇 |
1985年 | 194篇 |
1984年 | 222篇 |
1983年 | 182篇 |
1982年 | 264篇 |
1981年 | 250篇 |
1980年 | 185篇 |
1979年 | 124篇 |
1978年 | 132篇 |
1977年 | 115篇 |
1976年 | 79篇 |
1975年 | 79篇 |
1972年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Andrew F Shorr William L Jackson Brendan M Weiss Lisa K Moores 《Blood coagulation & fibrinolysis》2007,18(4):309-316
Multiple options exist for the prevention of deep vein thrombosis (DVT) in medical inpatients. We sought to determine the cost-effectiveness of low-molecular-weight heparin (LMWH) relative to unfractionated heparin (UFH) for DVT prevention in this setting. We conducted a cost-effectiveness analysis from the perspective of a third-party payer employing a decision model and literature-based estimates for inputs. In the base-case analysis, LMWH had little impact on the rate of DVT. Despite higher acquisition costs, however, LMWHs resulted in net savings. Routine use of LMWH saves approximately US$89 per patient. The lower rate of heparin-induced thrombocytopenia (HIT) with LMWH accounted for this differential. Univariate sensitivity analysis revealed the model was moderately sensitive to the odds ratio of HIT with LMWH and the cost of HIT. Multivariate sensitivity analysis confirmed the LMWH approach dominated financially. 'Worst-case' scenario modeling, where LMWH actually increased the risk for DVT, had little effect on the rate of HIT, and was substantially more costly than UFH, still demonstrated that LMWHs were economically superior. Monte-Carlo simulation indicated the 95% confidence interval around the estimate for savings with LMWH ranged from US$7 to US$373. We conclude that, despite their higher cost, LMWHs for thromboprophylaxis in medical patients result in savings. 相似文献
82.
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
83.
Clinical trial data and fracture risk prediction models unequivocally demonstrate the utility of identifying prevalent vertebral fractures to predict future fractures of all types. Knowledge of prevalent vertebral fractures can alter patient management decisions and result in initiation of therapy to reduce fracture risk in some patients who would not otherwise be treated. Cost-benefit analysis demonstrates that identifying and treating patients with vertebral fractures, even those with a densitometric classification of osteopenia, is cost effective. Vertebral fractures can be readily identified in the office setting using standard radiography or Vertebral Fracture Assessment (VFA), a software addition to a central dual-energy X-ray absorptiometry (DXA) machine. In the United States, VFA was assigned a Current Procedural Terminology (CPT) code in January 2005. Nevertheless, coverage of VFA has not been uniformly embraced by Medicare carriers, companies that contract with the federal government to administer Medicare coverage and process claims for a region of the United States. Unlike DXA, for which uniform national coverage of qualified Medicare beneficiaries is mandated by the Balanced Budget Act of 1997, VFA coverage policies are determined by the local Medicare carriers. Third-party insurers are also variable in their coverage of VFA. This International Society for Clinical Densitometry (ISCD) White Paper documents the role of VFA in the evaluation and treatment of women with postmenopausal osteoporosis and compares it with standard spine radiography. Arguments used by some Medicare carriers and insurers to deny coverage of VFA in the United States are analyzed and critiqued. For health care providers within the United States, this White Paper may serve as a resource to respond to insurers who deny coverage of VFA. For health care providers regardless of their country, this article underscores the value of VFA as an alternative to spine radiography in the evaluation and management of postmenopausal women with suspected osteoporosis. 相似文献
84.
85.
Benjamin Clapp Melba Jarmillo Valeria Vigil Luis Macias Marcia Bouton Cuatemoc Gallardo Andrew Kassir 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2007,11(2):242-245
BACKGROUND AND OBJECTIVES: The purpose of this study was to determine patient recall and comprehension after laparoscopic appendectomy in an underserved population. Laparoscopic surgery can lead to diagnostic uncertainty secondary to poor recall and variable port placement. METHODS: After institutional review board approval, we identified a cohort of patients who underwent laparoscopic appendectomy from 2000 to 2004 at a single institution. We then attempted to contact the patients to conduct a 10-question telephone survey, which determined whether the patient spoke English or Spanish as a primary language, ethnicity, educational level, and questions about recall of perioperative events and diagnoses. If we could not reach the patient, we tried to call back on 2 different occasions. RESULTS: Between 2000 and 2004, 186 patients underwent laparoscopic appendectomy. Of these, 65% were Hispanic. We found that only 17% of these patients returned for a postoperative visit. Only 19.3% could be contacted by phone. Forty-seven percent of the patients contacted by phone spoke Spanish exclusively. Overall 92% of patients contacted knew what operation they had, and gave their correct diagnosis. CONCLUSIONS: The low percentage of patients available to follow-up makes this study statistically insignificant. However, we believe that fact in itself is important. In Southwestern states, we see a large migrant population. This highlights the need to communicate effectively with the patients at the time of surgery, which we speculate we did based on the percentage of patients that knew their diagnosis. 相似文献
86.
John Walls Dr Nick Pidgeon Andrew Weyman Tom Horlick-Jones 《Health, risk & society》2004,6(2):133-150
The binary opposition of trusting or not trusting is inadequate to understand the often ambiguous and contradictory ideas people possess about risk regulators, particularly when knowledge and experience of such institutions is limited. The paper reports qualitative and quantitative data from a major study of public perceptions (n?=?30 focus groups) of UK risk regulators. We compare the complex and widely different ‘trust profiles’ of two regulatory organisations which are institutionally related (the Health and Safety Executive and the Railways Inspectorate) but very separate in the minds of our participants. The paper develops the notion of critical trust to interrogate the various ways in which people make sense of such organisations, as well as discussing the modes of reasoning that people deploy. The paper argues that views of participants are the outcome of a reconciliation of diverse perceptions concerning the role of the organisation, structural factors and the nature of the regulated risk. 相似文献
87.
88.
Keith J Murphy Andrew G Foley Alan W O'connell Ciaran M Regan 《Neuropsychopharmacology》2006,31(1):90-100
Recent data suggest that Alzheimer's patients who discontinue treatment with cholinesterase inhibitors have a significantly delayed cognitive decline as compared to patients receiving placebo. Such observations suggest cholinesterase inhibitors to provide a disease-modifying effect as well as symptomatic relief and, moreover, that this benefit remains after drug withdrawal. Consistent with this suggestion, we now demonstrate that chronic administration of tacrine, nefiracetam, and deprenyl, drugs that augment cholinergic function, increases the basal frequency of dentate polysialylated neurons in a manner similar to the enhanced neuroplasticity achieved through complex environment rearing. While both drug-treated and complex environment reared animals continue to exhibit memory-associated activation of hippocampal polysialylated neurons, the magnitude is significantly reduced suggesting that such interventions induce a more robust memory pathway that can acquire and consolidate new information more efficiently. This hypothesis is supported by our findings of improved learning behavior and enhanced resistance to cholinergic deficits seen following either intervention. Furthermore, the level of enhancement of basal neuroplastic status achieved by either drug or environmental intervention correlates directly with improved spatial learning ability. As a combination of both interventions failed to further increase basal polysialylated cell frequency, complex environment rearing and chronic drug regimens most likely enhanced cognitive performance by the same mechanism(s). These findings suggest that improved memory-associated synaptic plasticity may be the fundamental mechanism underlying the disease modifying action of drugs such as cholinesterase inhibitors. Moreover, the molecular and cellular events underpinning neuroplastic responses are identified as novel targets in the search for interventive drug strategies for the treatment of neurodegenerative and neuropsychiatric disorders. 相似文献
89.
Nicholas L. Shortt Gary F. Keenan Andrew Y. Muir Prof. Dr. A. Hamish R. W. Simpson 《Operative Orthopadie und Traumatologie》2006,18(4):364-376
OBJECTIVE: Avoidance of potential iatrogenic nerve injury during insertion of Ilizarov fine wires into areas of high anatomic risk by using a modified nerve stimulation technique. INDICATIONS: Application of the Ilizarov ring fixator to areas of high anatomic hazard, in situations where anatomic topography may be distorted by previous surgery, trauma, or congenital anomalies. CONTRAINDICATIONS: Use of systemic muscle relaxants. Caution in patient with cardiac pacemaker. SURGICAL TECHNIQUE: Preliminary experiments showed that a standard nerve-stimulating device can deliver a negatively charged, monophasic square pulse of current through Ilizarov wires. During the application of an Ilizarov frame to potentially hazardous anatomic regions, providing no systemic muscle relaxants are used, a voltage field sufficient to cause nerves in close proximity to the Ilizarov wire to depolarize is produced. Identification of a distal muscle twitch provoked by the stimulation may indicate a potential for iatrogenic nerve injury. RESULTS: Results show that with the nerve stimulator set at 2.5 mA (pulsed at a frequency of 2 Hz), peripheral nerves are stimulated if they lie within 5 mm of the wires. Should a distal muscle twitch occur, wires should be repositioned so that equivalent stimulation produces no twitch. The technique was used during Ilizarov frame application in ten patients, with only a single occurrence of distal muscle twitches in a lower-leg frame. Following repositioning of the Ilizarov wire in this case, no further twitches were observed, indicating that no Ilizarov wire was inserted close to peripheral nerves. No neurologic impairment was present postoperatively. 相似文献
90.
Growth hormone signalling: sprouting links between pathways, human genetics and therapeutic options.
Iwona Pilecka Andrew Whatmore Rob Hooft van Huijsduijnen Benoit Destenaves Peter Clayton 《Trends in Endocrinology and Metabolism》2007,18(1):12-18
Our molecular understanding of growth hormone-induced signal transduction has improved significantly over the past decades. At the same time, human population genetics and the analysis of genetically engineered animals have led to the discovery of genes that control specific aspects of the overall growth process. Although, currently, growth disorders are still diagnosed and treated on empirical bases, it might soon be possible to stratify patients predominantly by genetic defect, with treatment based on our molecular understanding of the role of the affected gene in the disease. 相似文献