全文获取类型
收费全文 | 113684篇 |
免费 | 43714篇 |
国内免费 | 86篇 |
专业分类
耳鼻咽喉 | 1776篇 |
儿科学 | 5889篇 |
妇产科学 | 1717篇 |
基础医学 | 20428篇 |
口腔科学 | 5419篇 |
临床医学 | 16829篇 |
内科学 | 29438篇 |
皮肤病学 | 8082篇 |
神经病学 | 17683篇 |
特种医学 | 2869篇 |
外科学 | 17193篇 |
综合类 | 363篇 |
现状与发展 | 1篇 |
一般理论 | 94篇 |
预防医学 | 9269篇 |
眼科学 | 1807篇 |
药学 | 7999篇 |
中国医学 | 1039篇 |
肿瘤学 | 9589篇 |
出版年
2024年 | 85篇 |
2023年 | 666篇 |
2022年 | 1081篇 |
2021年 | 3267篇 |
2020年 | 6115篇 |
2019年 | 12338篇 |
2018年 | 11803篇 |
2017年 | 12563篇 |
2016年 | 13354篇 |
2015年 | 13231篇 |
2014年 | 13635篇 |
2013年 | 14589篇 |
2012年 | 7573篇 |
2011年 | 7373篇 |
2010年 | 10527篇 |
2009年 | 6691篇 |
2008年 | 4252篇 |
2007年 | 3183篇 |
2006年 | 2883篇 |
2005年 | 2478篇 |
2004年 | 2208篇 |
2003年 | 1939篇 |
2002年 | 1904篇 |
2001年 | 894篇 |
2000年 | 782篇 |
1999年 | 431篇 |
1998年 | 265篇 |
1997年 | 162篇 |
1996年 | 134篇 |
1995年 | 136篇 |
1994年 | 133篇 |
1993年 | 114篇 |
1992年 | 74篇 |
1991年 | 57篇 |
1990年 | 50篇 |
1989年 | 41篇 |
1988年 | 32篇 |
1987年 | 29篇 |
1986年 | 43篇 |
1985年 | 38篇 |
1984年 | 35篇 |
1983年 | 29篇 |
1982年 | 32篇 |
1981年 | 39篇 |
1980年 | 33篇 |
1979年 | 18篇 |
1978年 | 16篇 |
1975年 | 10篇 |
1974年 | 11篇 |
1972年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
C. M. Crceles J. M. Serrano P. Marín E. Escudero E. Fernndez‐Varn 《Transboundary and Emerging Diseases》2006,53(6):300-304
The pharmacokinetics (PK) of moxifloxacin in healthy white New Zealand rabbits was studied following intravenous (IV) and subcutaneous (SC) administration routes as well as a SC long‐acting poloxamer 407 gel formulation (SC‐P407). Moxifloxacin concentrations were determined by high‐performance liquid chromatography assay with fluorescence detection. Mean half‐life for IV, SC and SC‐P407 routes was 2.15, 5.41 and 11.09 h. Clearance value after IV dosing was 0.78 l/kg/h. After SC administration, the mean absolute bioavailability was 117% and the Cmax was 1.61 ± 0.49 mg/l. After SC‐P407 administration, the bioavailability was 44% and the Cmax 1.83 was ±0.62 mg/l. No adverse effects were observed in any of the rabbits following IV, SC and SC‐P407 administration of moxifloxacin. Minimal inhibitory concentrations of moxifloxacin against different strains of Staphylococcus aureus from different european countries were used to compute the main pharmacodynamic (PD) surrogate markers of efficacy. The high tolerability of this SC‐P407 formulation and the favourable PK behaviour such as the long half‐life, acceptable bioavailability and excellent PK–PD ratios achieved indicate that it is likely to be effective in rabbits. 相似文献
22.
Validation of a simplified technique for using the POPQ pelvic organ prolapse classification system 总被引:3,自引:2,他引:1
Steven Swift Sarah Morris Vikki McKinnie Robert Freeman Eckhard Petri Richard J. Scotti Peter Dwyer 《International urogynecology journal》2006,17(6):615-620
Our objective was to determine the inter-examiner agreement of a simplified pelvic organ prolapse quantification (POPQ) exam and to assess its correlation with the standard POPQ exam. This study consists of two parts; both were preformed in a prospective, randomized, blinded fashion on women presenting with complaints attributed to pelvic organ support defects. The first study was done to determine the inter-examiner reliability of a simplified POPQ exam. The simplified POPQ exam is based on the POPQ with similar ordinal staging but with only four points measured instead of nine. Forty-eight women underwent exams by five different investigators. The order of exams was randomized and the examiners were blinded to the results of each other’s findings. The results of these two exams were compared using weighted kappa statistics. The second part of the study was done to determine the inter-system agreement between the simplified vs standard POPQ exam. A group of 49 women were examined by four different investigators: one using the simplified and the other using standard POPQ exams. The order of the exams was randomized and the examiners were blinded to the results of each other’s exam. Kendall’s tau-b statistics were used to determine the inter-system agreement. For the inter-examiner reliability of the POPQ exam, the average age was 60±13 years. The weighted kappa statistics for the inter-examiner reliability of the simplified prolapse classification system were 0.86 for the overall stage, 0.89 and 0.86 for the anterior and posterior vaginal walls, respectively, 0.82 for the apex/cuff, and 0.72 for the cervix. All demonstrate significant agreement. For the inter-system association between the simplified POPQ and standard POPQ, the average age was 61±15 year. The Kendall’s tau-b value for overall stage was 0.90, 0.83, and 0.87 for the anterior and posterior walls respectively, and 0.78 for the cuff/apex and 0.98 for the cervix. There is good inter-examiner agreement of a simplified POPQ classification system and it appears to have good inter-system association with the POPQ.IUGA Standardization of Terminology Committee members: Robert Freeman MD (chairman), Steven Swift, Eckhard Petri MD, Richard J. Scotti MD, and Peter Dwyer MD. 相似文献
23.
24.
Sarah L Barber 《International journal for quality in health care》2006,18(4):306-313
OBJECTIVE: To evaluate variations in prenatal care quality by public and private clinical settings and by household wealth. DESIGN: The study uses 2003 data detailing retrospective reports of 12 prenatal care procedures received that correspond to clinical guidelines. The 12 procedures are summed up, and prenatal care quality is described as the average procedures received by clinical setting, provider qualifications, and household wealth. SETTING: Low-income communities in 17 states in urban Mexico. PARTICIPANTS: A total of 1253 women of reproductive age who received prenatal care within 1 year of the survey. MAIN OUTCOME MEASURE: The mean of the 12 prenatal care procedures received, reported as unadjusted and adjusted for individual, household, and community characteristics. RESULTS: Women received significantly more procedures in public clinical settings [80.7, 95% confidence interval (CI) = 79.3-82.1; P < or = 0.05] compared with private (60.2, 95% CI = 57.8-62.7; P < or = 0.05). Within private clinical settings, an increase in household wealth is associated with an increase in procedures received. Care from medical doctors is associated with significantly more procedures (78.8, 95% CI = 77.5-80.1; P < or = 0.05) compared with non-medical doctors (50.3, 95% CI = 46.7-53.9; P < or = 0.05). These differences are independent of individual, household, and community characteristics that affect health-seeking behavior. CONCLUSIONS: Significant differences in prenatal care quality exist across clinical settings, provider qualifications, and household wealth in urban Mexico. Strategies to improve quality include quality reporting, training, accreditation, regulation, and franchising. 相似文献
25.
26.
Abstract: Background: Identification of risk drinking in expectant fathers may be helpful as an important part of efforts to minimize maternal alcohol use, and as an opportunity to inform them about a problematic practice during a critical developmental stage for the couple. The purpose of this study was to evaluate the T‐ACE screening questionnaire, which asks about t olerance to alcohol, being a nnoyed by other's comments about drinking, attempts to c ut down, and having a drink first thing in the morning (“ e ye‐opener”), in the male partners of pregnant women who themselves were T‐ACE positive. Methods: Two hundred fifty‐four male partners were asked to complete the T‐ACE embedded in a health survey, the Alcohol Use Disorders Identification Test (AUDIT), and other questions about their alcohol use in the past 30 days when their pregnant partners had a median gestation of 11.5 weeks (T1). After delivery, male partners again completed the T‐ACE and quantity‐frequency questions (T2). The predictive ability of the T‐ACE and AUDIT was compared, using risk drinking (>4 drinks/day or >14 drinks/week) as the criterion standard. Results: A substantial minority of male partners had risk drinking, 31 percent at T1 and 25 percent at T2. Although the AUDIT was better than the T‐ACE as an independent predictor of risk drinking, the latter was most accurate when the tolerance threshold exceeded 2 drinks, the same established for pregnant women. The sensitivity (T1 = 84.6%, T2 = 82.8%) and specificity (T1 = 43.8%, T2 = 51.1%) of the T‐ACE at this threshold compared favorably with those of the AUDIT at the standard cut point of 8. Conclusions: The T‐ACE may be a practical way for clinicians to identify risk drinking in both pregnant women and expectant fathers. (BIRTH 33:2 June 2006) 相似文献
27.
28.
Sarah A. Taylor Jacqueline Benedetti David Schuller Stephen P. Richman Goronwy O. Broun Alexander Hantel 《Investigational new drugs》1993,11(2-3):227-229
Summary Twenty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with piroxantrone 150 mg/m2 intravenously every 21 days. There were no objective responses. The 95% upper confidence bound for response is 15%. Primary toxicity was hematologic. 相似文献
29.
Sally M. Bradberry Sarah A. Cage Alex T. Proudfoot J. Allister Vale 《Adverse drug reactions and toxicological reviews》2005,24(2):93-106
The first pyrethroid pesticide, allethrin, was identified in 1949. Allethrin and other pyrethroids with a basic cyclopropane carboxylic ester structure are type I pyrethroids. The insecticidal activity of these synthetic pyrethroids was enhanced further by the addition of a cyano group to give α-cyano (type II) pyrethroids, such as cypermethrin. The finding of insecticidal activity in a group of phenylacetic 3-phenoxybenzyl esters, which lacked the cyclopropane ring but contained the α-cyano group (and hence were type II pyrethroids) led to the development of fenvalerate and related compounds. All pyrethroids can exist as at least four stereoisomers, each with different biological activities. They are marketed as racemic mixtures or as single isomers. In commercial formulations, the activity of pyrethroids is usually enhanced by the addition of a synergist such as piperonyl butoxide, which inhibits metabolic degradation of the active ingredient. Pyrethroids are used widely as insecticides both in the home and commercially, and in medicine for the topical treatment of scabies and headlice. In tropical countries mosquito nets are commonly soaked in solutions of deltamethrin as part of antimalarial strategies. Pyrethroids are some 2250 times more toxic to insects than mammals because insects have increased sodium channel sensitivity, smaller body size and lower body temperature. In addition, mammals are protected by poor dermal absorption and rapid metabolism to non-toxic metabolites. The mechanisms by which pyrethroids alone are toxic are complex and become more complicated when they are co-formulated with either piperonyl butoxide or an organophosphorus insecticide, or both, as these compounds inhibit pyrethroid metabolism. The main effects of pyrethroids are on sodium and chloride channels. Pyrethroids modify the gating characteristics of voltage-sensitive sodium channels to delay their closure. A protracted sodium influx (referred to as a sodium ‘tail current’) ensues which, if it is sufficiently large and/or long, lowers the action potential threshold and causes repetitive firing; this may be the mechanism causing paraesthesiae. At high pyrethroid concentrations, the sodium tail current may be sufficiently great to prevent further action potential generation and ‘conduction block’ ensues. Only low pyrethroid concentrations are necessary to modify sensory neurone function. Type II pyrethroids also decrease chloride currents through voltage-dependent chloride channels and this action probably contributes the most to the features of poisoning with type II pyrethroids. At relatively high concentrations, pyrethroids can also act on GABA-gated chloride channels, which may be responsible for the seizures seen with severe type II poisoning. Despite their extensive world-wide use, there are relatively few reports of human pyrethroid poisoning. Less than ten deaths have been reported from ingestion or following occupational exposure. Occupationally, the main route of pyrethroid absorption is through the skin. Inhalation is much less important but increases when pyrethroids are used in confined spaces. The main adverse effect of dermal exposure is paraesthesiae, presumably due to hyperactivity of cutaneous sensory nerve fibres. The face is affected most commonly and the paraesthesiae are exacerbated by sensory stimulation such as heat, sunlight, scratching, sweating or the application of water. Pyrethroid ingestion gives rise within minutes to a sore throat, nausea, vomiting and abdominal pain. There may be mouth ulceration, increased secretions and/or dysphagia. Systemic effects occur 4–8 hours after exposure. Dizziness, headache and fatigue are common, and palpitations, chest tightness and blurred vision less frequent. Coma and convulsions are the principal life-threatening features. Most patients recover within 6 days, although there were seven fatalities among 573 cases in one series and one among 48 cases in another. Management is supportive. As paraesthesiae usually resolve in 12–24 hours, specific treatment is not generally required, although topical application of dl-α tocopherol acetate (vitamin E) may reduce their severity. 相似文献
30.
Bartczak Andi Weiss; Sangaiah Ramiah; Ball Louise M.; Warren Sarah H.; Gold Avram 《Mutagenesis》1987,2(2):101-105
Many polycyclic aromatic hydrocarbons containing peripherallyfused cyclopenta rings are believed to be activated primarilyby epoxidation of the cyclopenta ring. The cyclopenta epoxidesof a series of four cyclopenta benzanthracene derivatives, benz[e]aceanthrylene-5,6-oxide,benz[j]ace-anthrylene-1,2-oxide, benz(l)anthrylene-1,2-oxideand benz[k]acephenaceanthrylene-4,5-oxide were synthesized fromtheir parent hydrocarbons by formation of the bromohydrin followedby dehydrobromination, and characterized by u.v. vis,and 1H n.m.r. spectroscopy and mass spectrometry. The mutagenicityof these compounds was investigated in the Ames plate incorporationassay with Salmonella typhimurium strain TA98. All the oxideswere active without exogenous metabolic activation (170320His+ revertants per nanomole) and also toxic above 0.5 µg/plate.Addition of S9 protein did not increase, and generally decreased,the mutagenicity of the oxides, while toxicity was largely unchanged.These results are consistent with the postulated role of cyclopentaoxides as major contributors to the mutagenicity of the parentcompounds in the Ames assay. 相似文献