全文获取类型
收费全文 | 35060篇 |
免费 | 3962篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 206篇 |
儿科学 | 1100篇 |
妇产科学 | 991篇 |
基础医学 | 4874篇 |
口腔科学 | 700篇 |
临床医学 | 4828篇 |
内科学 | 6225篇 |
皮肤病学 | 552篇 |
神经病学 | 3038篇 |
特种医学 | 1423篇 |
外国民族医学 | 3篇 |
外科学 | 4436篇 |
综合类 | 793篇 |
一般理论 | 43篇 |
预防医学 | 4304篇 |
眼科学 | 881篇 |
药学 | 2584篇 |
中国医学 | 45篇 |
肿瘤学 | 2026篇 |
出版年
2021年 | 624篇 |
2020年 | 347篇 |
2019年 | 578篇 |
2018年 | 670篇 |
2017年 | 543篇 |
2016年 | 595篇 |
2015年 | 620篇 |
2014年 | 825篇 |
2013年 | 1198篇 |
2012年 | 1649篇 |
2011年 | 1615篇 |
2010年 | 971篇 |
2009年 | 879篇 |
2008年 | 1466篇 |
2007年 | 1556篇 |
2006年 | 1539篇 |
2005年 | 1478篇 |
2004年 | 1443篇 |
2003年 | 1352篇 |
2002年 | 1277篇 |
2001年 | 1204篇 |
2000年 | 1209篇 |
1999年 | 1039篇 |
1998年 | 444篇 |
1997年 | 408篇 |
1996年 | 381篇 |
1995年 | 326篇 |
1994年 | 348篇 |
1993年 | 332篇 |
1992年 | 817篇 |
1991年 | 787篇 |
1990年 | 772篇 |
1989年 | 673篇 |
1988年 | 695篇 |
1987年 | 653篇 |
1986年 | 600篇 |
1985年 | 664篇 |
1984年 | 537篇 |
1983年 | 422篇 |
1982年 | 271篇 |
1981年 | 280篇 |
1980年 | 255篇 |
1979年 | 462篇 |
1978年 | 346篇 |
1977年 | 256篇 |
1976年 | 273篇 |
1975年 | 253篇 |
1974年 | 285篇 |
1973年 | 263篇 |
1972年 | 268篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The efficacy of acute beta blockade in essential hypertension is limited by reflex vasoconstriction. The aim of this study was to determine whether the latter response was modified by prior selective alpha-1-adrenoceptor blockade. A single-blind, within-patient, placebo-controlled evaluation of the immediate hemodynamic effects of sequential alpha-1 (trimazosin)- and beta (propranolol)-adrenoceptor blockade was undertaken in 10 men (34 to 58 years) with previously untreated essential hypertension. The study commenced with a 4-minute control period of constant-load (600 to 900 kpm/min) upright bicycle exercise, and measurements were made before (control) and 30 minutes after intravenous trimazosin (2 mg/kg) and exercise was then repeated; measurements at rest were again made 4 minutes after intravenous propranolol (0.2 mg/kg) before a final exercise period. Trimazosin at rest reduced systolic and diastolic arterial pressure and systemic vascular resistance without change in heart rate, cardiac output, or left ventricular (LV) filling pressure. During upright bicycle exercise the reductions in blood pressure were sustained without change in their rest-to-exercise increments. Other circulatory variables did not differ from control values. At rest the addition of propranolol further reduced systolic arterial pressure. Heart rate and cardiac output fell and systemic vascular resistance increased to its pretreatment control value. During exercise the changes at rest were sustained and the rest-to-exercise increments in blood pressure, heart rate, and cardiac output were reduced. LV filling pressure was significantly increased. In conclusion, alpha-1-adrenoceptor blockade modified the adverse effects of acute beta blockade at rest but not during exercise. 相似文献
992.
993.
G G Clark C H Calisher C L Crabbs K M Canestorp R B Tesh R A Bowen D E Taylor 《The American journal of tropical medicine and hygiene》1988,39(6):586-592
Two virus isolates, 1 each from Aedes campestris and Psorophora signipennis mosquitoes collected in south central New Mexico in August 1985, were shown by neutralization tests to be identical to each other, but not to any of more than 250 arthropod-borne and other viruses. Electron microscopy of 1 isolate (85-488NM, chosen as the prototype) indicated that this strain shares morphologic characteristics with viruses of the family Rhabdoviridae. Indirect fluorescent antibody tests indicated that this virus is a member of the genus Vesiculovirus, but is not closely related to any of the North American or other rhabdoviruses with which it was tested, including vesicular stomatitis (Indiana) and vesicular stomatitis (New Jersey) viruses. The name Malpais Spring virus is proposed for this newly recognized vesiculovirus. A serologic survey indicated that Malpais Spring virus infects indigenous (mule deer and pronghorn) and exotic (gemsbok) ungulates at and near the sites where the mosquitoes from which the virus strains were isolated were collected. Antibody prevalence in wild animals indicates that the pronghorn and gemsbok may play roles as hosts for Malpais Spring, epizootic hemorrhagic disease (New Jersey), and bluetongue viruses in this area. 相似文献
994.
Hyperammonemic encephalopathy in urinary diversion with urea-splitting urinary tract infection 总被引:1,自引:0,他引:1
F F Kaveggia J S Thompson E C Schafer J L Fischer R J Taylor 《Archives of internal medicine》1990,150(11):2389-2392
We present two cases of hyperammonemic encephalopathy secondary to urea-splitting urinary tract infection with urinary diversion. One patient had a ureterosigmoidostomy, the other an ileal loop diversion. Neither patient had significant underlying liver disease, but both had considerable muscle atrophy that may have predisposed them to develop hyperammonemia. Medical therapy did not provide long-term control of symptoms. In both cases, hyperammonemic encephalopathy resolved after revision of their urinary diversions. The probable mechanism of the metabolic derangements produced by urea-splitting urinary tract infections is reviewed. We suggest that patients with urinary diversion who develop hyperammonemic encephalopathy secondary to a urea-splitting urinary tract infection be treated with surgical revision of the urinary system to improve drainage and decrease bowel contact time. 相似文献
995.
Age differences in religious participation among black adults 总被引:2,自引:0,他引:2
Age differences in level of religious participation were examined using data from the National Survey of Black Americans (N = 2107). Seven indicators of organizational, nonorganizational, and attitudinal forms of religious involvement were examined. For women, age was positively associated with each of the religiosity measures; among men, requests for prayer from others was the only indicator for which age was not a significant predictor. The findings are discussed in relation to previous work on age and religious participation. 相似文献
996.
Taylor V Thompson B Lessler D Yasui Y Montano D Johnson KM Mahloch J Mullen M Li S Bassett G Goldberg HI 《Journal of general internal medicine》1999,14(2):104-111
OBJECTIVE: The objective was to evaluate the effect of a clinic-based intervention program on mammography use by inner-city women. DESIGN: A randomized controlled trial employing firm system methodology was conducted. SETTING: The study setting was a general internal medicine clinic in the university-affiliated county hospital serving metropolitan Seattle. PARTICIPANTS: Women aged 50 to 74 years with at least one routine clinic appointment (when they were due for mammography) during the study period were enrolled in the trial (n = 314). INTERVENTIONS: The intervention program emphasized nursing involvement and included physician education, provider prompts, use of audiovisual and printed patient education materials, transportation assistance in the form of bus passes, preappointment telephone or postcard reminders, and rescheduling assistance. Control firm women received usual care. MEASUREMENTS AND MAIN RESULTS: Mammography completion within 8 weeks of clinic visits was significantly higher among intervention (49%) than control (22%) firm women (p < .001). These effects persisted after adjustment for potential confounding by age, race, medical insurance coverage, and previous mammography experience at the hospital (odds ratio 3.5; 95% confidence interval 1.9, 6.5). The intervention effect was modified by type of insurance coverage as well as prior mammography history. Process evaluation indicated that bus passes and rescheduling efforts did not contribute to the observed increases in screening participation. CONCLUSIONS: A clinic-based program incorporating physician education, provider prompts, patient education materials, and appointment reminders and emphasizing nursing involvement can facilitate adherence to breast cancer screening guidelines among inner-city women. 相似文献
997.
This study examined the immediate effects of exposure to a patient education brochure concerning the risks and benefits of zidovudine (ZDV) therapy during pregnancy to reduce perinatal HIV transmission (protocol ACTG 076) on related knowledge, behavioural intentions and attitudes of women with and at-risk for HIV-infection. Self-reports were collected from 653 women of childbearing age from community family planning clinics and hospital-based HIV centres in 19 sites from nine US cities between May and November 1995. The intervention was a nine-page patient education brochure in Spanish, Creole and English versions, evently presenting the pros and cons of ZDV therapy to reduce perinatal HIV-transmission. Brochure exposure increased knowledge (p < 0.001) for all but one scale concerning ZDV resistance and increased the likelihood of women reporting intentions to take ZDV during pregnancy (p < 0.001) and to believe ZDV reduced transmission (p < 0.001). Brochure exposure had differential effects for some subpopulations. Intentions to have or terminate current or future pregnancies, knowledge about ZDV and attitudes toward ZDV varied mostly by ethnicity/race, language preference and HIV status. Pregnancy status, age, education and having an HIV-positive child had less impact on the brochure's effect, while income had no impact. 相似文献
998.
C A Dujovne S B Chernoff P Krehbiel B Jackson S DeCoursey H Taylor 《The American journal of cardiology》1984,53(11):1514-1518
The hypocholesterolemic and adverse effects of colestipol, 20 g/day, and colestipol, 10 g/day combined with probucol, 1 g/day, were compared. A double-placebo, diet-controlled, crossover trial that lasted 19 months was undertaken on 22 hypercholesterolemic patients who had low-density lipoprotein (LDL) cholesterol levels greater than 180 mg/dl after 3 months of diet and placebo treatment. Uniformity of diet and physical activity were monitored throughout the study. Compared with baseline values after 3 months on diet-placebo treatment, "combined" therapy reduced LDL cholesterol by more than 20% in 15 patients, more than 25% in 9 patients and more than 45% in 2 patients. Treatment with "half-dose" colestipol and probucol resulted in the greatest mean LDL cholesterol reduction, from 239 mg/dl during diet-placebo period to 170 mg/dl; the difference was not statistically significantly different from the reduction to 180 mg/dl with 20 g of colestipol alone. Fifteen patients showed the greatest reduction in LDL cholesterol after combined therapy. Probucol produced statistically significant reductions in very low density lipoprotein and high-density lipoprotein cholesterol. The major gastrointestinal side effects of single therapy with colestipol (constipation) and probucol (diarrhea) were ameliorated or abolished by concomitant administration. Probucol-colestipol co-administration allowed a 50% reduction in the colestipol dosage, with similar efficacy and improved tolerability and reduced mean serum LDL cholesterol with a frequency and magnitude rarely seen with other hypocholesterolemic treatments. Hypercholesterolemic persons who cannot tolerate full doses of resins may receive equal benefit by half the dose if probucol is added to the regimen. 相似文献
999.
Taylor BV Williamson J Luck J Coleman D Jones D McGregor A 《Internal medicine journal》2004,34(5):250-258
BACKGROUND: The measurement of serum antibodies to Campylobacter spp. has been used to investigate links between prior Campylobacter infections and the development of Guillain-Barre syndrome and its variants. Little is known of the serum antibody response to acute infections in the short- or long-term. AIMS: The aims of the present study were to investigate the normal serum response to an acute Campylobacter infection and the sensitivity and specificity of anti-Campylobacter antibodies in determining recent Campylobacter infection. METHODS: An enzyme-linked immunosorbent assay (ELISA) method was used to measure serum anti-Campylobacter immunoglobulin G (IgG), IgA and IgM antibodies. Controls consisted of 420 blood donors without recent gastroenteritis, 25 patients with other gastrointestinal infections, 24 patients with neurological conditions not affecting the peripheral nerves and 19 patients with autoimmune disorders. Three patient groups were assessed: 99 patients with acute Campylobacter infections, all of whom were tested 3 weeks post-infection; 69 of these patients tested 3-6 months later; and 74 additional patients tested >20 months post-infection. Western blot analysis was performed on controls and patients with high titre anti-Campylobacter antibodies to assess for cross-reactivity and specificity. RESULTS: Following acute infections, all antibody classes rose in the majority of but not in all patients, followed by decreasing titres that did not return to baseline levels. Sixteen per cent of enteritis cases did not demonstrate a rise in titres and 9% of cases had significant levels of antibodies >20 months post-infection. The ELISA used was shown to be highly specific for the detection of Campylobacter antibodies. CONCLUSION: The use of Campylobacter-specific antibody levels as the sole marker of prior infection is an unreliable method of determining the association between Campylobacter infection and neurological disease. 相似文献
1000.
Differential antibody recognition of FC27-like Plasmodium falciparum merozoite surface protein MSP2 antigens which lack 12 amino acid repeats 总被引:1,自引:0,他引:1
Lisa C. Ranford-Cartwright Rachel R. Taylor Nima Asgari-Jirhandeh Donald B Smith Paul E. Roberts V.Jane Robinson Hamza A. Babiker Eleanor M. Riley David Walliker & Jana S. McBride 《Parasite immunology》1996,18(8):411-420
Three alleles of the FC27-type allelic family of the MSP2 gene of the malaria parasite Plasmodium falciparum have been sequenced from parasites from the field (The Gambia and Tanzania). These alleles lack the 12 amino acid repeat units which are usual in this family of MSP2 alleles. We have investigated the recognition by sera from an endemic area (The Gambia) of three recombinant MSP2 proteins that have 5, 1 and no copies of this repeat region. Antibody recognition of these recombinant proteins varied according to the number of repeats present. High titre antibody levels were seen with most sera using the recombinant protein with 5 × 12-mer repeats, whereas only low responses were measured using proteins containing 1 or no 12-mer repeats. Several sera entirely failed to recognise the protein which lacked 12-mer repeats. The data suggest that variation in the number of tandem repeat sequences could allow the parasite to avoid high avidity antibody binding and this may allow escape from immune recognition. 相似文献