全文获取类型
收费全文 | 23386篇 |
免费 | 1792篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 192篇 |
儿科学 | 899篇 |
妇产科学 | 696篇 |
基础医学 | 2968篇 |
口腔科学 | 242篇 |
临床医学 | 4079篇 |
内科学 | 4062篇 |
皮肤病学 | 311篇 |
神经病学 | 2225篇 |
特种医学 | 357篇 |
外科学 | 1976篇 |
综合类 | 378篇 |
一般理论 | 49篇 |
预防医学 | 3510篇 |
眼科学 | 217篇 |
药学 | 1328篇 |
中国医学 | 19篇 |
肿瘤学 | 1721篇 |
出版年
2023年 | 116篇 |
2022年 | 189篇 |
2021年 | 472篇 |
2020年 | 299篇 |
2019年 | 479篇 |
2018年 | 514篇 |
2017年 | 375篇 |
2016年 | 412篇 |
2015年 | 464篇 |
2014年 | 643篇 |
2013年 | 1098篇 |
2012年 | 1579篇 |
2011年 | 1582篇 |
2010年 | 858篇 |
2009年 | 812篇 |
2008年 | 1569篇 |
2007年 | 1722篇 |
2006年 | 1581篇 |
2005年 | 1554篇 |
2004年 | 1552篇 |
2003年 | 1379篇 |
2002年 | 1386篇 |
2001年 | 180篇 |
2000年 | 142篇 |
1999年 | 197篇 |
1998年 | 345篇 |
1997年 | 264篇 |
1996年 | 238篇 |
1995年 | 209篇 |
1994年 | 199篇 |
1993年 | 182篇 |
1992年 | 120篇 |
1991年 | 90篇 |
1990年 | 120篇 |
1989年 | 86篇 |
1988年 | 114篇 |
1987年 | 79篇 |
1986年 | 89篇 |
1985年 | 100篇 |
1984年 | 116篇 |
1983年 | 100篇 |
1982年 | 173篇 |
1981年 | 134篇 |
1980年 | 137篇 |
1979年 | 67篇 |
1978年 | 81篇 |
1976年 | 75篇 |
1975年 | 71篇 |
1974年 | 73篇 |
1973年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVE: To compare the efficacy and tolerability of once daily (OD) tramadol tablets with normal release tramadol capsules (50 mg) taken 3 or 4 times daily in a multicenter, double blind, double dummy parallel study. METHODS: Patients with moderate to severe pain due to osteoarthritis (OA) were recruited from general practice. Following a titration period of a week, patients were assessed over one month for the analgesic efficacy and tolerability of the test medications. RESULTS: Both treatments were shown to be effective. There was no difference between treatments and both produced good pain control as shown by clinically relevant decreases from baseline pain scores, low escape medication use, and sleep disturbance. The efficacy of the OD tramadol over the 24 h dosing interval was confirmed by the low sleep disturbance, absence of "end of dose" effects in morning pain scores, and low escape medication use. Of the 279 patients recruited, 140 withdrew, mostly because of adverse events. The adverse event profiles were typical of opioids and were similar for both treatments. CONCLUSION: Tramadol OD was at least as effective and well tolerated as normal release tramadol in the management of OA pain. However, OD tramadol offers the advantage of a reduced dosing regimen, which is especially valuable in the elderly population. 相似文献
992.
Mitchell LA Thomas PQ Zacharin MR Scheffer IE 《AJNR. American journal of neuroradiology》2002,23(9):1475-1481
BACKGROUND AND PURPOSE: Ectopic posterior pituitary lobe often occurs in children with growth hormone deficiency and is part of the spectrum associated with septo-optic dysplasia. Some cases of septo-optic dysplasia are caused by homozygous mutations in the homeobox gene HESX1, whereas heterozygous mutations are associated with milder phenotypes. To date, HESX1 is the only gene associated with ectopic posterior pituitary lobe. We describe an association between ectopic posterior pituitary lobe and periventricular heterotopia in four children without classic features of septo-optic dysplasia and suggest possible mechanisms on the basis of a review of pituitary embryology and recent molecular genetic advances. METHODS: Among 20 children with ectopic posterior pituitary lobe, four had associated periventricular heterotopia. We herein review the clinical and MR imaging findings of these four children. Mutation screening of HESX1 was performed in two. RESULTS: All four children had growth hormone deficiency. None had visual or neurologic disturbances. MR images showed a range of pituitary appearances, with scattered discrete periventricular heterotopia in each case. Other abnormalities were limited to small suprasellar lipomas and callosal dysgenesis. A heterozygous HESX1 mutation was present in one case. CONCLUSION: The coexistence of ectopic posterior pituitary lobe and periventricular heterotopia suggests they have a common underlying genetic basis that is due to gene expression at different locations and stages of development. The presence of a heterozygous HESX1 mutation in one case suggests this gene is important in the development of both ectopic posterior pituitary lobe and periventricular heterotopia and supports their place in the spectrum of septo-optic dysplasia. Further analysis of HESX1 and other genes in related developmental pathways will elucidate their roles in the development of both malformations. 相似文献
993.
Haq MR Kalatzis V Gubler MC Town MM Antignac C Van't Hoff WG Woolf AS 《Journal of the American Society of Nephrology : JASN》2002,13(8):2046-2051
Cystinosis is an autosomal recessive disorder associated with excessive lysosomal cystine accumulation secondary to defective lysosomal cystine efflux. CTNS, the gene mutated in cystinosis, codes for the lysosomal membrane protein cystinosin. Antisera were raised in rabbits to a carboxy-terminal oligopeptide sequence from cystinosin. Antisera were screened by Western blotting and immunocytochemical analyses of transfected COS-7 cells expressing either human wild-type cystinosin, a wild-type cystinosin-green fluorescent protein (GFP) fusion protein, or a fusion protein of GFP and mutant human cystinosin with a carboxy-terminal deletion. In Western blots, bands corresponding to cystinosin or cystinosin-GFP were observed in transfected cells but no signal was detected in cells expressing the carboxy-terminal mutant; preimmune sera yielded negative results in all three cases. In transfected cells expressing wild-type cystinosin, immunoreactivity appeared in subcellular vesicles. In cells expressing the wild-type cystinosin-GFP fusion protein, immunoreactivity colocalized with GFP fluorescence. Previous studies demonstrated that GFP fluorescence from this construct colocalized with immunostaining for a known lysosomal membrane protein, i.e., lysosome-associated membrane protein 2. In immunohistochemical analyses, cystinosin localized to tubule epithelia in three normal human kidneys, with a pattern similar to that of lysosome-associated membrane protein 2; cystinosin immunoreactivity was absent in kidneys from patients with a CTNS deletion. For the first time, antisera have been raised that localize cystinosin in cells in vitro and in vivo. 相似文献
994.
With evidence of increasing accident risk due to age-related declines in health and cognition affecting driver performance, there is a need for research promoting safe mobility of older people. The present study aimed to identify transport options and licensing issues for a group of older people in an Australian community. Ninety-five participants aged 75 and over were interviewed about their driving status and accident record and tested for cognitive ability. After stratification on cognitive level and driver status (current, ex-driver or non-driver), 30 were selected for further in-depth interviews concerning demographics, license status and impact of change, travel options available and used, and travel characteristics. Considerable reliance on the motor vehicle as the mode of transport and the decision to cease driving were major quality-of-life issues. There was little evidence of planning and support in making the decision to stop driving. Some differences in transport decisions on the basis of cognitive level were evident; however, people with severely compromised cognitive ability (and, therefore, unable to give informed consent) had been excluded. The study suggested the need for resources to assist older people/carers/health professionals to plan for the transition from driver to non-driver and to manage alternative transport options more effectively. 相似文献
995.
996.
There are few good-quality studies of the effectiveness of antibiotic treatment of proven group A streptococcal (GAS) pharyngitis in children; available data suggest that antibiotics may reduce symptom duration. While there is limited justification for antibiotic treatment of GAS pharyngitis to prevent acute rheumatic fever in non-Indigenous Australians, there is no justification for routine antibiotic treatment of all patients with sore throat. Two strategies are open to clinicians: not to treat GAS pharyngitis with antibiotics, in which case no investigations should be done; or to treat cases of sore throat with clinical features that suggest GAS, in which case diagnosis should be confirmed with a throat swab, and penicillin started while awaiting the result. Penicillin should be discontinued if the swab is negative, or continued for 10 days if it is positive for GAS. Surveillance of GAS infections and acute rheumatic fever is needed in Australia, as are further studies of effectiveness (including cost-effectiveness) of antibiotic treatment of proven GAS pharyngitis. 相似文献
997.
Hemorrhagic fever viruses as biological weapons: medical and public health management 总被引:17,自引:1,他引:16
Borio L Inglesby T Peters CJ Schmaljohn AL Hughes JM Jahrling PB Ksiazek T Johnson KM Meyerhoff A O'Toole T Ascher MS Bartlett J Breman JG Eitzen EM Hamburg M Hauer J Henderson DA Johnson RT Kwik G Layton M Lillibridge S Nabel GJ Osterholm MT Perl TM Russell P Tonat K;Working Group on Civilian Biodefense 《JAMA》2002,287(18):2391-2405
OBJECTIVE: To develop consensus-based recommendations for measures to be taken by medical and public health professionals if hemorrhagic fever viruses (HFVs) are used as biological weapons against a civilian population. PARTICIPANTS: The Working Group on Civilian Biodefense included 26 representatives from academic medical centers, public health, military services, governmental agencies, and other emergency management institutions. EVIDENCE: MEDLINE was searched from January 1966 to January 2002. Retrieved references, relevant material published prior to 1966, and additional sources identified by participants were reviewed. CONSENSUS PROCESS: Three formal drafts of the statement that synthesized information obtained in the evidence-gathering process were reviewed by the working group. Each draft incorporated comments and judgments of the members. All members approved the final draft. CONCLUSIONS: Weapons disseminating a number of HFVs could cause an outbreak of an undifferentiated febrile illness 2 to 21 days later, associated with clinical manifestations that could include rash, hemorrhagic diathesis, and shock. The mode of transmission and clinical course would vary depending on the specific pathogen. Diagnosis may be delayed given clinicians' unfamiliarity with these diseases, heterogeneous clinical presentation within an infected cohort, and lack of widely available diagnostic tests. Initiation of ribavirin therapy in the early phases of illness may be useful in treatment of some of these viruses, although extensive experience is lacking. There are no licensed vaccines to treat the diseases caused by HFVs. 相似文献
998.
999.
Leah D Stuchal Kevin M Kleinow John J Stegeman Margaret O James 《Drug metabolism and disposition》2006,34(6):932-938
Exposure to the organochlorine pesticide methoxychlor (MXC) is associated with endocrine disruption in several species through biotransformation to mono-desmethyl-MXC (OH-MXC) and bis-desmethyl-MXC (HPTE), which interact with estrogen receptors. The biotransformation of [14C]methoxychlor was examined in channel catfish (Ictalurus punctatus), a freshwater species found in the southern United States. Hepatic microsomes formed OH-MXC and HPTE, assessed by comigration with authentic standards. The Km for OH-MXC formation by control liver microsomes was 3.8 +/- 1.3 microM (mean +/- S.D., n = 4), and Vmax was 131 +/- 53 pmol/min/mg protein. These values were similar to those of catfish pretreated with 2 mg/kg methoxychlor i.p. for 6 days (Km 3.3 +/- 0.8 microM and Vmax 99 +/- 17 pmol/min/mg) but less (p < 0.05) than the kinetic parameters for catfish treated with 3-methylcholanthrene (3-MC), which had Km of 6.0 +/- 1.1 microM and Vmax of 246 +/- 6 pmol/min/mg protein. Liver microsomes from 3-MC-treated fish produced significantly more of the secondary metabolite and more potent estrogen, HPTE. Intestinal microsomes formed OH-MXC at lower rates than liver. Methoxychlor pretreatment significantly reduced intestinal metabolite formation from 32 +/- 4 to 15 +/- 6 pmol/min/mg (mean +/- S.D., n = 4), whereas 3-MC treatment significantly increased OH-MXC production to 72 +/- 22 pmol/min/mg. Ketoconazole, clotrimazole, and alpha-naphthoflavone all decreased the production of OH-MXC in liver microsomes, whereas alpha-naphthoflavone stimulated HPTE formation, suggesting that CYP1 and CYP3 family isozymes demethylated methoxychlor. The results suggest that the formation of estrogenic metabolites from methoxychlor would be more rapid in catfish coexposed to CYP1 inducers. 相似文献
1000.
This study explored the experiences and perceptions of sexuality and HIV/AIDS among 15–24 year-old young people with physical disabilities in a South African Township characterised by high unemployment rates and lack of social services. Ten young people and ten parents participated in multiple individual interviews as well as in focus group discussions. The analysis of audio taped and transcribed responses identified common experiences and perceptions among participants. The results indicate that disabled young people have limited factual knowledge about sexuality and HIV/AIDS. The decisions and choices they make about sexual behaviour are not informed by what they know; rather, they are part of the whole life situation in Nyanga. Their need to be loved and accepted, need for job security and family life, were more important than practicing ‘safe sex’. Therefore, there is need for HIV/AIDS programme developers to take into account the experiences and perceptions of the target population.In this paper the phrases ‘young people with physical disabilities’ and disabled young people’ are used interchangeably. 相似文献