首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   137911篇
  免费   9534篇
  国内免费   706篇
耳鼻咽喉   1652篇
儿科学   3588篇
妇产科学   2470篇
基础医学   17597篇
口腔科学   2953篇
临床医学   13544篇
内科学   28464篇
皮肤病学   1824篇
神经病学   12005篇
特种医学   5785篇
外科学   21906篇
综合类   1960篇
现状与发展   1篇
一般理论   173篇
预防医学   12484篇
眼科学   2935篇
药学   9683篇
  4篇
中国医学   179篇
肿瘤学   8944篇
  2023年   676篇
  2022年   1055篇
  2021年   2582篇
  2020年   1480篇
  2019年   2410篇
  2018年   2955篇
  2017年   2134篇
  2016年   2250篇
  2015年   2753篇
  2014年   4062篇
  2013年   6112篇
  2012年   8899篇
  2011年   9473篇
  2010年   5341篇
  2009年   4890篇
  2008年   8432篇
  2007年   9071篇
  2006年   8608篇
  2005年   8764篇
  2004年   8394篇
  2003年   7884篇
  2002年   7705篇
  2001年   1311篇
  2000年   1077篇
  1999年   1424篇
  1998年   1754篇
  1997年   1457篇
  1996年   1382篇
  1995年   1323篇
  1994年   1145篇
  1993年   1101篇
  1992年   866篇
  1991年   898篇
  1990年   789篇
  1989年   785篇
  1988年   799篇
  1987年   779篇
  1986年   807篇
  1985年   879篇
  1984年   932篇
  1983年   882篇
  1982年   1154篇
  1981年   1184篇
  1980年   989篇
  1979年   635篇
  1978年   676篇
  1977年   615篇
  1976年   544篇
  1975年   482篇
  1974年   471篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Three saxophone players with upper limb amputations have been successfully rehabilitated to play their musical instruments using skin-conductivity touch control. Each attained a standard of musicianship sufficient to perform the standard repertoire of the instrument in a concert setting. The mechanical and electrical modifications to the saxophone are described, as well as the principles of operation of the skin-conductivity touch control module. The touch control module is commercially available for prosthetists who wish to fit musicians or others with upper extremity amputations who require rapid accurate control of a number of channels of powered prosthetic function.  相似文献   
72.
A cross-sectional survey on respiratory health in swine producers showed that 30% of 301 examined men usually used a dust mask when working inside a barn. They did not differ significantly from dust mask nonusers in respect to respiratory symptoms and lung function. This analysis was undertaken to determine whether the respiratory health of dust mask users was associated with reasons why they had started individual respiratory protection. The subjects were recontacted in order to identify those who started using a mask to deliberately prevent symptoms (42 men) and those who started protection because of pre-existing respiratory symptoms (44 men). Not unexpectedly, betweengroup comparisons of respiratory symptoms and lung function suggest that swine producers who wear dust masks for preventive purposes have better respiratory health than those who wear dust masks because of symptoms or those who do not use individual respiratory protection. The individual reasons for starting dust mask usage should be examined among potential determinants of the outcomes of prospective studies which can then provide more valid assessment of the effect of individual respiratory protection. © 1993 Wiley-Liss, Inc.  相似文献   
73.
Study Objectives . To evaluate the pharmacodynamic antibacterial activity of ticarcillin-clavulanic acid (T-C) and ampicillin-sulbactam (A-S) combinations against reference bacterial strains in patients with end-stage renal disease maintained on long-term hemodialysis. Design . Randomized, crossover, controlled study. Setting . National Institutes of Health-funded general clinical research unit in a Veterans Administration Medical Center. Patients . Nine adult men with end-stage renal disease maintained on long-term hemodialysis. Two subjects did not complete the study due to problems of vascular access, and another withdrew for personal reasons. Interventions . On a nondialysis day, each subject was randomly administered either T-C 3.1 g or A-S 3 g as a slow intravenous infusion over 30 minutes. Serial blood samples were collected for measurement of antibiotic serum concentrations and determination of serum bactericidal titers. Following a washout period, the study was repeated with the alternative antibiotic combination. Measurements and Main Results . The mean observed apparent β-half-life of clavulanic acid was substantially shorter than that for the other three drugs. The bactericidal activity of both A-S and T-C against non-β-lactamase-producing (Nβ-LP) strains of S. aureus and E. coli was consistently high, as indicated by geometric mean SBTs of at least 1:5 at 24 hours. Against β-lactamase-producing (β-LP) S. aureus, the geometric mean SBTs for A-S were at least 1:25 throughout the study period, while the geometric mean SBTs for T-C decreased over 24 hours from 1:29 to 1:6. Against β-LP E. coli, the bactericidal activities for both A-S and T-C were poor, with geometric mean peak SBTs of only 1:6 and 1:3, respectively. The geometric mean SBT for T-C against this E. coli strain had declined to 1:1 at 6 hrs. Conclusion . Increasing the dosing interval for T-C in patients with end-stage renal disease may lead to periods of insufficient clavulanic acid to protect ticarcillin from β-lactamase degradation.  相似文献   
74.
Study Objectives . To characterize patient sociodemographics and health, describe vancomycin treatment parameters and clinician-rated outcomes, and determine costs associated with treatment including preparation and administration, adverse events, and toxicity. Design . A prospective study to develop a model for costs associated with antibiotic treatment (vancomycin). Setting . A community hospital. Patients . One hundred adults with active infections. Interventions . Mean duration of therapy was 10 days, and most patients received 2000 mg/day. Serum concentrations were monitored in two of three patients. Detailed cost analyses were completed on a subset of 26 patients selected at random from the overall sample. Measurements and Main Results . Sepsis and skin and skin structure infections were the most common indications for vancomycin therapy. Treatment was effective in 81 patients, failed in 9, and was not evaluable in 10. Thirty-eight percent of patients experienced adverse events attributable to the drug. Phlebitis was common, and red man syndrome, nephrotoxicity, and ototoxicity were infrequent. Conclusions . Total cost of vancomycin treatment for 100 patients was $30,251: $23,855 for preparation and administration, $1710 for monitoring serum concentrations, and $4686 for treating adverse reactions. Drug costs accounted for only 55% of the total cost. Vancomycin is safe and effective, but phlebitis is underreported and significantly affects cost.  相似文献   
75.
Study Objective . To compare digoxin tablets and liquid-filled capsules with respect to excretion of the drug and its metabolites in urine and feces at steady state. Design . A randomized, crossover trial, each period lasting 3 weeks, with no washout period. Setting . A university hospital. Patients . Six patients, five of whom were elderly, with histories of gastrointestinal disorders, such as hypochlorhydria, intestinal bacterial overgrowth, and inflammatory bowel disease. Interventions . The patients received digoxin once/day in either tablet or capsule form for 3 weeks, and then were switched to the other formulation. Total urinary and fecal excretion from the last 3 days of each regimen were analyzed for the drug and metabolites. Measurements and Main Results . No statistically significant differences were found between tablets and capsules in recovery of digoxin or its metabolites in urine or feces (p=0.05). One subject had a 4-fold increase in urinary drug excretion and 50% decrease in fecal excretion after taking the capsules compared with tablets. Intersubject variability in extent and type of metabolite excretion was greater than intrasubject variability. Conclusions . Fecal analyses may be an accurate way to classify patients as formers of digoxin reduction products.  相似文献   
76.
MK-679 (R(?)-3-((3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)(3-(dimethylamino)-3-oxopropyl)thio)methyl)thio(propanoic acid) is a potent and specific LTD4-receptor antagonist. The disposition of MK-679 was investigated in a three-way crossover study in 12 healthy males receiving single intravenous doses of 75, 250, and 500 mg of MK-679. A greater than proportional increase in the area under the plasma concentration—time curve of MK-679 was observed with increase in dose. The plasma concentration data for each subject fitted well to the differential equations for a two-compartment model with linear tissue distribution and Michaelis-Menten elimination from the central compartment, indicating that the elimination of MK-679 in humans is saturable. In a previous study, the disposition of MK-679 in humans was also dose-dependent when given together with its S(+)-isomer, L-668,018. Thus, the disposition of MK-679 in humans is dose-dependent regardless of the presence of its stereoisomer. Also, the bioavailability of MK-679 was determined in six healthy males receiving simultaneously an oral dose of 250 mg of MK-679 and intravenous infusion of 1 mg 14C-MK-679. Results of this study indicate that the oral bioavailability of MK-679 is nearly quantitative.  相似文献   
77.
78.
79.
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号