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   11769篇
  免费   704篇
  国内免费   41篇
耳鼻咽喉   118篇
儿科学   409篇
妇产科学   244篇
基础医学   1880篇
口腔科学   209篇
临床医学   1028篇
内科学   2339篇
皮肤病学   389篇
神经病学   1246篇
特种医学   414篇
外科学   1091篇
综合类   75篇
一般理论   3篇
预防医学   862篇
眼科学   234篇
药学   1062篇
中国医学   14篇
肿瘤学   897篇
  2023年   75篇
  2022年   235篇
  2021年   402篇
  2020年   223篇
  2019年   258篇
  2018年   340篇
  2017年   252篇
  2016年   330篇
  2015年   338篇
  2014年   399篇
  2013年   565篇
  2012年   827篇
  2011年   835篇
  2010年   441篇
  2009年   381篇
  2008年   639篇
  2007年   673篇
  2006年   659篇
  2005年   622篇
  2004年   651篇
  2003年   561篇
  2002年   527篇
  2001年   170篇
  2000年   167篇
  1999年   142篇
  1998年   101篇
  1997年   104篇
  1996年   78篇
  1995年   64篇
  1994年   61篇
  1993年   60篇
  1992年   95篇
  1991年   103篇
  1990年   110篇
  1989年   101篇
  1988年   70篇
  1987年   84篇
  1986年   71篇
  1985年   78篇
  1984年   52篇
  1983年   51篇
  1982年   46篇
  1981年   25篇
  1980年   26篇
  1979年   36篇
  1978年   42篇
  1975年   28篇
  1974年   35篇
  1973年   33篇
  1972年   31篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
There is some controversy over the treatment of acromioclavicular injuries. The use of the Rockwood classification as the basis for decisions on whether operative or nonoperative treatment is indicated is discussed critically, and the authors' preferred operative technique is described and illustrated by examples. We treat injuries classified according to the Rockwood classification as types I and II with conservative methods. In type III injuries the patient's age, job and free time activities determine whether or not surgery is indicated. In the case of type IV or type VI injuries we always perform temporary internal fixation of the acromioclavicular joint, using transarticular K-wire fixation or hookplate osteosynthesis. Satisfactory results of both operative and nonoperative treatment are reported in the literature. The authors' own results are presented.  相似文献   
32.
Perinatal child abuse prevention projects are increasingly favored but rarely evaluated. The paper describes an experimental evaluation of the Child Parent Enrichment Project (CPEP). Women were referred to the project during or just after pregnancy if identified as at-risk of engaging in child abuse by community professionals. Clients were randomly assigned to CPEP services (n=24) or traditional community services (n=26). CPEP services involved six months of home visiting by paraprofessional women and linkage to other formal and informal community resources. Multivariate Analysis of Covariance on posttest scores, controlling for pretest scores, show advantage for the CPEP group in prenatal care, birth outcomes, better reports of child temperament, and better indicators of child welfare. CPEP mothers tended to report better well-being. No significant differences were demonstrated for levels of formal and informal support. Reports of child abuse were similar for both groups. Consumer satisfaction indicates that clients valued the program. The preliminary results argue for further use and evaluation of perinatal child abuse prevention services.The authors thank Sharon Ikami and CPEP staff and volunteers. Richard P. Barth, D.S.W. is Associated Professor at the School of Social Welfare, University of California, Berkeley. Susan Hacking, Ph.D. was Project Director and Jordana Ash, M.S.W. is Child Welfare Worker, Alameda County Department of Social Services. Funding was provided by Bio-Medical Research Support Grant 2-507-RR07006 Resources from the Division of Research National Institute of Health, the State of California Office of Child Abuse Prevention, and the Office of Human Development Services ACYF, DHHS (Grant #90-CA-0998).  相似文献   
33.
The Infant Behavioral Summarized Evaluation (IBSE) is a rating scale adapted from the Behavioral Summarized Evaluation (BSE) and specifically related to the assessment of behaviors of young children having autistic disorders. Content validity and reliability studies described in the paper were made from behavior ratings of videotapes for 89 children aged from 6 to 48 months. Results show a significant group of 19 items including some characteristic early autistic behaviors (communicative and social abnormalities) and some that are less commonly described in the syndrome (attentional, perceptive, and adaptive disorders). The value of the use of this scale for clinicians and professionals involved in behavioral evaluations and treatment of young children with developmental disorders and the necessity for further psychometric investigations are discussed.This study was supported by INSERM U.316 Nervous System from the Foetus to the Child. Development, Circulation, Metabolism, L. Pourcelot, INSERM, Network INSERM No. 489001, Grant INSERM No. 911182 (D. Savrage) No. 911008 (L. Hameury) MRT. No. 9906 Fondation Langlois. Gratitude is expressed to Professor G. Lelord who initiated and supervised this study. The authors thank Professor J. Fermanian, Department of Biostatistics, CHU Necker, Paris, for his helpful suggestions and assistance. They also thank Dr. Larmande, Dr. Leddet, Dr. Glorion, and Dr. Garreau for their medical participation in the study and C. Richard, C. Fillatre, J. Rabant, and F. Etourneau for the psychological assessments of children. Special thanks to G. Calzas, M. Barré, A. Lardeux, and D. Lioret for their technical assistance.  相似文献   
34.
The complement system (C) is one of the main humoral components of innate immunity. Three major tasks of C against invading pathogens are: (i) lysis of pathogens by the formation of the membrane attack complex (MAC); (ii) opsonization of pathogens with complement fragments to favor phagocytosis; and (iii) attraction of inflammatory cells by chemotaxis. Like other particles, HIV activates C and becomes opsonized. To escape complement-mediated lysis, HIV has adopted various properties, which include the acquisition of HIV-associated molecules (HAMs) belonging to the family of complement regulators, such as CD46, CD55, CD59, and the interaction with humoral regulatory factors like factor H (fH). Opsonized virus may bind to complement receptor positive cells to infect them more efficiently or to remain bound on the surface of such cells. In the latter case HIV can be transmitted to cells susceptible for infection. This review discusses several aspects of C-HIV interactions and provides a model for the dynamics of this process.  相似文献   
35.
The plastic pediatric BacT/ALERT (bioMérieux, Durham, N.C.) PF (PPF) is a new nonvented aerobic culture medium in a clear plastic bottle designed to prevent breakage. We compared the performance of the new PPF bottle to that of the present glass BacT/ALERT PF bottle for the recovery of microorganisms as well as for the time to detection of growth in samples of blood obtained for culture from children. We found that the PPF and PF bottles were comparable for recovery of microorganisms and that the safety advantage of plastic bottles can be achieved without compromising performance.  相似文献   
36.
Proactive rodents show a larger behavioral response to apomorphine (APO) than reactive copers, suggesting a more sensitive DA system in proactive individuals. Previously, chicks from a high feather pecking (HFP) and low feather pecking line (LFP) have been suggested to display a proactive and reactive coping strategy, respectively. Therefore, at approximately 4 weeks of age, the behavior of 48 LFP and 48 HFP chicks in response to an APO injection was studied using an open field. Another objective of the present study was to determine whether behavioral variation (in an open field) between HFP and LFP birds, after APO injection, is also reflected by variation of D(1) and D(2) receptor densities in the brain. Receptor binding capacities were assessed by measuring specific binding of tritiated D(1) and D(2) receptor ligands in different regions of the brain of control HFP and LFP chicks. In the present study, it is shown that indeed HFP chicks display a more enhanced behavioral response to acute APO treatment (0.5 mg/kg BW) than LFP birds in an open field. This difference was not reflected by variation of D(1) and D(2) receptor densities in the brain between both lines.  相似文献   
37.
Verapamil (V) is a specific inhibitor of the P-glycoprotein (mdr1) in the hepatocyte canalicular membrane. Cyclosporin A (CsA) as an essential immunosuppressive drug has potentially cholestatic adverse effects on the liver, but increases the expression of mdr1. In precision-cut liver slices from 34- to 40-day-old male Wistar rats 26 individual free and conjugated bile acids (BAs) as markers of hepatic transport and synthesis function were analysed after 4 h incubation with V (100 microM) or CsA (5 microM) in Krebs-Henseleit buffer. Some slices were loaded with cholic acid (CA 5 microM) or tauro-ursodeoxycholic acid (T-UDCA 5 microM) to investigate the V and CsA effects under conditions of BA supplementation. BAs were determined in tissue and medium by HPLC with postcolumn derivatisation and fluorescence detection. V and CsA, influencing different targets in BA transport, enhanced slice concentrations of T- and glyco- (G-) conjugated CA only when exogenous CA was given additionally. This BA accumulation in tissue is more reflected at decreased medium concentrations of these BAs after V and CsA incubations. Both V and CsA also inhibited CA uptake into the slices. The acidic chenodeoxycholic acid (CDCA) synthesis pathway is disturbed: T- and G-CDCA concentrations are diminished in slices and medium after V and CsA incubations. T-UDCA plus V or CsA enhanced not only its own slice concentration but also the concentration of the trihydroxylated tauro-muricholic acid (T-beta-MCA), reflecting the conversion of the accumulated dihydroxylated T-UDCA into the T-beta-MCA. The similar effects of V and CsA on BA transport and metabolism can be explained by mdr1 mediated disturbances of cellular ATP transport rather than by inhibition of individual BA transporters.  相似文献   
38.
X-linked adrenoleukodystrophy (X-ALD) is a progressive neurodegenerative disorder characterized by the accumulation of saturated and mono-unsaturated very long-chain fatty acids (VLCFA) and reduced peroxisomal VLCFA beta-oxidation activity. In this study, we investigated the role of VLCFA biosynthesis in X-ALD fibroblasts. Our data demonstrate that elongation of both saturated and mono-unsaturated VLCFAs is enhanced in fibroblasts from patients with peroxisomal beta-oxidation defects including X-ALD, and peroxisome biogenesis disorders. These data indicate that enhanced VLCFA elongation is a general phenomenon associated with an impairment in peroxisomal beta-oxidation, and not specific for X-ALD alone. Analysis of plasma samples from patients with X-ALD and different peroxisomal beta-oxidation deficiencies revealed increased concentrations of VLCFAs up to 32 carbons. We infer that enhanced elongation does not result from impaired peroxisomal beta-oxidation alone, but is due to the additional effect of unchecked chain elongation. We demonstrate that elongated VLCFAs are incorporated into complex lipids. The role of chain elongation was also studied retrospectively in samples from patients with X-ALD previously treated with "Lorenzo's oil." We found that the decrease in plasma C26:0 previously found is offset by the increase of mono-unsaturated VLCFAs, not measured previously during the trial. We conclude that evaluation of treatment protocols for disorders of peroxisomal beta-oxidation making use of plasma samples should include the measurement of saturated and unsaturated VLCFAs of chain lengths above 26 carbon atoms. We also conclude that chain elongation offers an interesting target to be studied as a possible mode of treatment for X-ALD and other peroxisomal beta-oxidation disorders.  相似文献   
39.
Using Immuno-Mycologics (IMMY; Norman, Okla.) histoplasmal yeast (HY) and mycelial (HM) antibody complement fixation test antigens, we retested 1,386 samples that were initially tested with Meridian Diagnostics, Inc. (Cincinnati, Ohio), antigens. Histoplasma antibody was identified (greater than or equal to 1:16) in 20% of HY and 5% of HM samples reported to have titers of less than 1:8 with Meridian reagents. IMMY titers were at least fourfold higher than Meridian titers in 39% of HY and 54% of HM samples that initially had titers of greater than or equal to 1:8 with Meridian antigens. Because 30 of 58 (52%) samples from confirmed cases of histoplasmosis yielded negative results with Meridian antigens and positive results upon retesting with IMMY antigens, we concluded that the Meridian antigens had less reactivity with human histoplasmal antibody.  相似文献   
40.
Fluorescence in situ hybridization (FISH) using chromosome-specific DNA probes is rapidly becoming a part of clinical laboratory practice. However, as a relatively new clinical test, it is not yet standardized and for practical reasons each laboratory must establish its own criteria. For this purpose we have evaluated the specificity of a dual-color BCR/ABL translocation probe by establishing the range of BCR/ABL fusion-positive scores in a healthy donor group. The false positive rate (FPR), determined by the percent of FISH BCR/ABL fusion-positive cells found in the specimens of healthy donors, was estimated at 2.3% (mean = 1%-4%). Thus the cut-off value for false positive nuclei was set at 5%.  相似文献   
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