全文获取类型
收费全文 | 3205篇 |
免费 | 234篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 111篇 |
儿科学 | 243篇 |
妇产科学 | 46篇 |
基础医学 | 350篇 |
口腔科学 | 163篇 |
临床医学 | 281篇 |
内科学 | 820篇 |
皮肤病学 | 71篇 |
神经病学 | 358篇 |
特种医学 | 101篇 |
外科学 | 278篇 |
综合类 | 104篇 |
一般理论 | 1篇 |
预防医学 | 245篇 |
眼科学 | 21篇 |
药学 | 171篇 |
肿瘤学 | 77篇 |
出版年
2021年 | 34篇 |
2020年 | 17篇 |
2019年 | 42篇 |
2018年 | 49篇 |
2017年 | 34篇 |
2016年 | 39篇 |
2015年 | 37篇 |
2014年 | 65篇 |
2013年 | 110篇 |
2012年 | 125篇 |
2011年 | 153篇 |
2010年 | 87篇 |
2009年 | 107篇 |
2008年 | 165篇 |
2007年 | 151篇 |
2006年 | 173篇 |
2005年 | 192篇 |
2004年 | 161篇 |
2003年 | 146篇 |
2002年 | 167篇 |
2001年 | 101篇 |
2000年 | 105篇 |
1999年 | 85篇 |
1998年 | 55篇 |
1997年 | 46篇 |
1996年 | 37篇 |
1995年 | 36篇 |
1994年 | 20篇 |
1993年 | 30篇 |
1992年 | 62篇 |
1991年 | 76篇 |
1990年 | 64篇 |
1989年 | 79篇 |
1988年 | 60篇 |
1987年 | 68篇 |
1986年 | 58篇 |
1985年 | 59篇 |
1984年 | 45篇 |
1983年 | 29篇 |
1982年 | 23篇 |
1981年 | 28篇 |
1980年 | 23篇 |
1979年 | 36篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1976年 | 13篇 |
1974年 | 17篇 |
1973年 | 12篇 |
1972年 | 10篇 |
1971年 | 10篇 |
排序方式: 共有3441条查询结果,搜索用时 15 毫秒
11.
Benjamin Volovitz Jacob Amir Hagit Malik Maya Lerman Itzhak Varsano 《The Journal of asthma》1994,31(1):27-34
Administration of theophylline to asthmatic children is frequently associated with an adverse influence on their behavior. The efficacy and behavioral effects of the administration of high-dose theophylline (T) and ketotifen (K) in various combinations were evaluated prospectively in a double-blind, placebo controlled study in 55 children with moderately severe perennial asthma. During a baseline period of 2 weeks, theophylline (serum level of 10-20 μg/ml) was administered to all the children. After this period the patients were randomly allocated into four comparable groups. The children were treated during a 12-week period with: T + K-Placebo (T group); T + K (T + K group); half-dose T + K (T/ 2 + K group); or placebo of both T and K (P group). During the 12-week treatment period, as compared to the baseline period, only the three groups of children who received active therapy (T + P, T + K, T/2 + K) showed a similar reduction in the number of days with asthmatic symptomatology, improvement of the total asthmatic symptoms score, and increased PEFR. The behavioral activity of the children (assessed by the Conner's rating scale) improved significantly only in the groups receiving placebo or T/2 + K. The results of this study suggest that a combination therapy of half the recommended therapeutic dose of theophylline with ketotifen can be clinically as effective as therapy with a full dose of theophylline, but with significantly less adverse behavioral effects. 相似文献
12.
The results of external beam radiotherapy for clinically localized adenocarcinorna of the prostate in 448 patients treated in the period 1980–90 were reviewed. The average follow up was 4.9 years. The patients were aged 44–87 years (median 69 years) and all had histopathological evidence of adenocarcinoma by needle biopsy or transurethral resection of prostate. The histopathological grading was: 127 G1; 154 G2; 127 G3; 12 G4; 28 Gx. Clinical staging according to TNM (American Urological Association) was: 29 T0 (A2); 4 T1 (B1); 173 T2 (B2); 176 T3 (C1); 63 T4 (C2); 3 Tx. Routine surgical pelvic lymph node staging was not performed but patients had radiological (computerized tomography scan or lymphogram) nodal staging: 350 N0; 22 N1; 12 N2; 64 Nx. High energy linear accelerator external beam radiotherapy was given by multiple fields to total doses of 50–70 Gy (median 60 Gy). The majority of patients (307, 69%) was treated by a uniform policy under the care of one radiation oncologist (HM). The rates of local and distant failure at 5 years were 10% (s.e. = 2%) and 42% (s.e. = 3%), respectively. The late complication rate at 5 years was 25% (s.e. = 2%), comprising mild 16%, moderate 7% and severe 1.3%. The 5 year overall survival rate was 64% (s.e. = 2%) and the cancer-specific survival rate was 74% (s.e. = 3%). Both histological grade and clinical stage were strongly predictive of overall survival and distant failure. Only histological grade was predictive of local failure. Treatment with external beam radiotherapy for this common cancer resulted in survival and disease control rates that compare favourably with other published radiotherapy series and has been accompanied by acceptably low morbidity. 相似文献
13.
Karoly Jakab Brook Damon Françoise Marga Octavian Doaga Vladimir Mironov Ioan Kosztin Roger Markwald Gabor Forgacs 《Developmental dynamics》2008,237(9):2438-2449
The Differential Adhesion Hypothesis (DAH) posits that differences in adhesion provide the driving force for morphogenetic processes. A manifestation of differential adhesion is tissue liquidity and a measure for it is tissue surface tension. In terms of this property, DAH correctly predicts global developmental tissue patterns. However, it provides little information on how these patterns arise from the movement and shape changes of cells. We provide strong qualitative and quantitative support for tissue liquidity both in true developmental context and in vitro assays. We follow the movement and characteristic shape changes of individual cells in the course of specific tissue rearrangements leading to liquid-like configurations. Finally, we relate the measurable tissue-liquid properties to molecular entities, whose direct determination under realistic three-dimensional culture conditions is not possible. Our findings confirm the usefulness of tissue liquidity and provide the scientific underpinning for a novel tissue engineering technology. Developmental Dynamics 237:2438-2449, 2008. (c) 2008 Wiley-Liss, Inc. 相似文献
14.
Non-expression of a common mutation in the 21-hydroxylase gene: implications for prenatal diagnosis and carrier testing. 下载免费PDF全文
Mutation analysis in the family of a child with 21-hydroxylase deficiency showed that the father and affected child were homozygous for a mutation, A/C655G, believed to activate a cryptic splice site in intron 2 of the 21-hydroxylase gene. The father, who was clinically asymptomatic, showed no biochemical evidence of disease. These results create problems for the management of future pregnancies in such families and for the interpretation of the risk associated with carrier status for this mutation. 相似文献
15.
Selection of biomaterials for peripheral nerve regeneration using data from the nerve chamber model 总被引:11,自引:0,他引:11
Peripheral nerve regeneration has been studied in a variety of animal models. Of these, the nerve chamber model has clearly dominated. It has been used to generate a large base of data that, however, cannot be analyzed usefully due to lack of standardization of experimental conditions and assays. Lack of standardization of critical experimental parameters of the model has, however, greatly limited the opportunity to compare directly data from independent investigators; as a result, progress in understanding conditions for optimal nerve regeneration has been stunted. In this article, we provide an overview of the major experimental parameters that must be controlled in order to generate data from independent investigators that can be compared directly (normalized data). Such parameters include the gap length, animal species, and the identity of assays used to evaluate the product of the regenerative process. Use of the recently introduced concept of critical axon elongation, the gap length at which the probability of axonal outgrowth (reinnervation) across the gap is 50%, leads to generation of a normalized database that includes data from several independent investigators. Conclusions are drawn about the relative efficacy of the various biomaterials and devices employed. Nerve chamber configurations that had the highest regenerative activity were those in which the tube wall comprised collagen and certain synthetic biodegradable polymers rather than silicone, and was cell-permeable rather than protein-permeable. In addition, the following tube fillings showed very high regenerative activity: suspensions of Schwann cells; a solution either of acidic or basic fibroblast growth factor; insoluble ECM substrates rather than solutions or gels; polyamide filaments oriented along the tube axis; highly porous, insoluble analogs of the ECM with specific structure and controlled degradation rate. 相似文献
16.
Johnson JG Cohen P Kotler L Kasen S Brook JS 《Journal of consulting and clinical psychology》2002,70(5):1119-1128
Longitudinal data were used to investigate whether anxiety, depressive, disruptive, personality, or substance use disorders are associated with risk for the development of eating disorders during adolescence or early adulthood. Psychiatric disorders were assessed among 726 youths from a random community sample during adolescence and early adulthood. Depressive disorders during early adolescence were associated with elevated risk for the onset of eating disorders, dietary restriction, purging behavior, and recurrent weight fluctuations after preexisting eating problems and other psychiatric disorders were controlled statistically. Disruptive and personality disorders were independently associated with elevated risk for specific eating or weight problems. The present findings suggest that depressive disorders during early adolescence may contribute to the development of eating disorders during middle adolescence or early adulthood. 相似文献
17.
I Brook 《Journal of medical microbiology》1988,27(3):191-198
The relationships between capsulate and non-capsulate Bacteroides fragilis strains and Escherichia coli, and between capsulate and non-capsulate strains of the B. melaninogenicus group and Streptococcus pyogenes, were studied in a subcutaneous abscess model in mice. Selective antimicrobial agents directed against either aerobic or anaerobic bacteria were used alone or in combination to explore the effect of eradication of one component of the mixed infection. Single agent therapy effective against both aerobic and anaerobic flora was also employed. Single therapy of mixed infection directed at the elimination of only one organism (S. pyogenes, E. coli or Bacteroides sp.) caused significant reductions in the numbers of sensitive organisms and also smaller yet significant decreases in the numbers of insensitive organisms. However, the abscesses were not eliminated after such therapy. Combination therapy or use of a single agent (cefoxitin) directed against the aerobic and anaerobic components of the infection was more effective. Non-capsulate Bacteroides spp. became capsulate after passage in mice mixed with either S. pyogenes or E. coli. Therapy directed at the elimination of S. pyogenes and E. coli did not prevent the emergence of capsulate Bacteroides spp. These data demonstrate the synergy between all members of the B. fragilis group and E. coli and between the B. melaninogenicus group and S. pyogenes, and reiterate the need to direct antimicrobial therapy at the eradication of the aerobic and anaerobic components of mixed infections. 相似文献
18.
Dales RE Cakmak S Judek S Dann T Coates F Brook JR Burnett RT 《The Journal of allergy and clinical immunology》2004,113(2):303-306
BACKGROUND: The risk of hospitalization for asthma caused by outdoor aeroallergens is largely unknown. OBJECTIVE: The objective of this study was to determine the association between changes in outdoor aeroallergens and hospitalizations for asthma from the Pacific coast to the Atlantic coast of Canada. METHODS: A daily time series analysis was done to test the association between daily changes in aeroallergens and daily changes in hospitalizations for asthma during a 7-year period between 1993 and 2000 in 10 of the largest cities in Canada. Results were adjusted for long-term trends, day of the week, climate, and air pollution. RESULTS: A daily increase, equivalent to the mean value of each allergen, was associated with the following percentage increase in asthma hospitalizations: 3.3% (95% CI, 2.3 to 4.1) for basidiomycetes, 3.1% (95% CI, 2.8 to 5.7) for ascomycetes, 3.2% (95% CI, 1.6 to 4.8) for deuteromycetes, 3.0% (95% CI, 1.1 to 4.9) for weeds, 2.9% (95% CI, 0.9 to 5.0) for trees, and 2.0% (95% CI, 1.1 to 2.8) for grasses. After accounting for the independent effects of trees and ozone, the combination of the 2 was associated with an additional 0.22% increase in admissions averaged across cities (P <.05). CONCLUSION: These findings provide evidence for the hypothesis that aeroallergens are an important cause of severe asthma morbidity across Canada, and in some situations there might be a modest synergistic adverse effect of ozone and aeroallergens combined. 相似文献
19.
Termination of Medi-Cal benefits. A follow-up study one year later 总被引:14,自引:0,他引:14
N Lurie N B Ward M F Shapiro C Gallego R Vaghaiwalla R H Brook 《The New England journal of medicine》1986,314(19):1266-1268
20.
Termination from Medi-Cal--does it affect health? 总被引:16,自引:0,他引:16