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   4814篇
  免费   406篇
  国内免费   7篇
耳鼻咽喉   25篇
儿科学   254篇
妇产科学   151篇
基础医学   657篇
口腔科学   51篇
临床医学   816篇
内科学   845篇
皮肤病学   63篇
神经病学   400篇
特种医学   78篇
外科学   295篇
综合类   103篇
一般理论   7篇
预防医学   744篇
眼科学   115篇
药学   285篇
中国医学   4篇
肿瘤学   334篇
  2023年   22篇
  2022年   34篇
  2021年   73篇
  2020年   46篇
  2019年   72篇
  2018年   78篇
  2017年   56篇
  2016年   83篇
  2015年   103篇
  2014年   109篇
  2013年   203篇
  2012年   250篇
  2011年   288篇
  2010年   147篇
  2009年   162篇
  2008年   271篇
  2007年   281篇
  2006年   325篇
  2005年   343篇
  2004年   321篇
  2003年   324篇
  2002年   300篇
  2001年   35篇
  2000年   29篇
  1999年   52篇
  1998年   64篇
  1997年   56篇
  1996年   44篇
  1995年   42篇
  1994年   29篇
  1993年   41篇
  1992年   29篇
  1991年   31篇
  1990年   37篇
  1989年   30篇
  1988年   39篇
  1986年   28篇
  1985年   24篇
  1984年   28篇
  1983年   44篇
  1982年   48篇
  1981年   46篇
  1980年   29篇
  1979年   29篇
  1978年   23篇
  1977年   33篇
  1975年   23篇
  1974年   26篇
  1973年   27篇
  1971年   20篇
排序方式: 共有5227条查询结果,搜索用时 11 毫秒
51.
Quit-rates for cigarette smokers in a lifestyle intervention program aimed at reducing coronary risk were 24 percent for all participants and 34 percent for non-dropouts. Recidivism remained very low during participation in the program. Half of the smokers who quit did so after being in the program more than two years. These data suggest that while engaging in an effort to make other changes in lifestyle, many smokers can be helped to quit. Sustained antismoking efforts in the clinical practice of medicine can be expected to share these same positive aspects. While mass public health programs to eliminate smoking and prevent young people from taking up the habit are being developed, health practitioners can make a significant contribution by including vigorous efforts at smoking cessation as part of routine practice.  相似文献   
52.
Both intact fetal cells as well as cell-free fetal DNA are present in the maternal circulation and can be recovered for non-invasive prenatal genetic diagnosis. Although methods for enrichment and isolation of rare intact fetal cells have been challenging, diagnosis of fetal chromosomal aneuploidy including trisomy 21 in first- and second-trimester pregnancies has been achieved with a 50-75% detection rate. Similarly, cell-free fetal DNA can be reliably recovered from maternal plasma and assessed by quantitative PCR to detect fetal trisomy 21 and paternally derived single gene mutations. Real-time PCR assays are robust in detecting low-level fetal DNA concentrations, with sensitivity of approximately 95-100% and specificity near 100%. Comparing intact fetal cell versus cell-free fetal DNA methods for non-invasive prenatal screening for fetal chromosomal aneuploidy reveals that the latter is at least four times more sensitive. These preliminary results do not support a relationship between frequency of intact fetal cells and concentration of cell-free fetal DNA. The above results imply that the concentration of fetal DNA in maternal plasma may not be dependent on circulating intact fetal cells but rather be a product of growth and cellular turnover during embryonic or fetal development.  相似文献   
53.
54.
Summary We have prepared monoclonal antibodies to each of the enteric adenoviruses types 40 and 41. Three different hybridoma cell lines were selected which produced antibody found to react by radioimmunoprecipitation with adenovirus (Ad) hexon antigens. One was specific for Ad 40, another for Ad 41, and a third one reacted with both types. When tested in an enzyme immunoassay against all 41 known human Ad types, the type-specific monoclonal antibody against Ad 40 reacted homotypically, as did the monoclonal antibody against Ad 41. In addition, these monoclonal antibodies neutralized the homologous enteric Ad type. The monoclonal antibody which reacted with both enteric Ad types also showed lower levels of reactivity with the group C adenoviruses types 2, 5, and 6. The monoclonal antibodies produced will provide a definitive means for rapid identification of specific Ad types, and will be useful in defining the relationship of enteric adenoviruses to other types.  相似文献   
55.
The concurrent and predictive validity of 2 different methods of Millon Clinical Multiaxial Inventory-III subtyping (protocol sorting, cluster analysis) was evaluated in 125 recently detoxified opioid-dependent outpatients in a 12-week randomized clinical trial. Participants received naltrexone and relapse prevention group counseling and were assigned to 1 of 3 intervention conditions: (a) no-incentive vouchers, (b) incentive vouchers alone, or (c) incentive vouchers plus relationship counseling. Affective disturbance was the most common Axis I protocol-sorted subtype (66%), antisocial-narcissistic was the most common Axis II subtype (46%), and cluster analysis suggested that a 2-cluster solution (high vs. low psychiatric severity) was optimal. Predictive validity analyses indicated less symptom improvement for the higher problem subtypes, and patient treatment matching analyses indicated that some subtypes had better outcomes in the no-incentive voucher conditions.  相似文献   
56.
This study considered whether cognitive profile could distinguish groups of children where genes or environment played a major role in influencing reading level. Same-sex twin pairs from an epidemiological study were categorized according to parental report at 4 years of age into those with low language skills and a typically developing group. A total of 132 same-sex twin pairs from the low language group and 66 from the control group were assessed at 6 years of age, to investigate heritability of reading ability adjusted for nonverbal IQ. For pairs where both twins had normal scores on a nonword repetition test, heritability was zero, with environmental influences explaining all the variance. For pairs where one or both twins had low nonword repetition, the heritability estimate was 0.79 and the variance due to shared environment was zero. Future studies of genetics of reading development should treat those with poor nonword repetition skills as a separate subgroup.  相似文献   
57.
The main aim of this study is to evaluate relationships linking social stigma, HIV/AIDS knowledge, and sexual risk among African American (AA) and South African (SA) college students. One major barrier to HIV prevention efforts is the social stigma associated with HIV/AIDS. Based on the Burkholder et al. (1999) findings, persons who engage in greater stigmatization of persons with AIDS (PWA) and gay people are associated with greater sexual behavior risk for HIV/AIDS. The present study attempted to replicate the Burkholder et al. study using African American and South African college students, but the findings were inconsistent with the aforementioned study. AA respondents had higher social stigma of PWA and gays and higher condom self‐efficacy. While SA respondents were less likely to stigmatize PWA and gay persons and had high‐perceived risk of being infected, they reported engaging in high‐risk sexual behavior. The authors discuss the differences that may account for the dissimilar findings.  相似文献   
58.
IntroductionDetermining the efficacy of anti-scar technologies can be difficult as qualitative, subjective assessments are often utilized instead of systematic, objective measures. Perceptions regarding the reliability of instruments for quantitative measurements along with their high cost and increased data collection time may discourage their use, leading to use of scar scales which are relatively quick and low-cost. To directly evaluate the reliability of instruments for quantitative measurements of scar properties, instruments and two qualitative scales were compared by assessing a variety of cutaneous scars.MethodsScar height and surface texture were evaluated using a 3D scanner and a mold/cast technique. Scar color was evaluated by using a spectroscopy-based tool, the Mexameter®, and digital photography with image analysis. Scar biomechanics were evaluated using the BTC-2000?, Dermal Torque Meter (DTM®), and ballistometer®. The Vancouver Scar Scale (VSS) and Patient and Observer Scar Assessment Scale (POSAS) were used to qualitatively evaluate the same scar properties. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-user reliability (poor, moderate, good, excellent) with all instruments and the kappa reliability statistic was used to asses inter-user reliability (poor, fair, moderate, good, very good) for VSS and POSAS. Time for measurement collection and after collection analysis was also recorded.ResultsThe Mexameter® was the most reliable method for evaluating erythema and pigmentation compared to digital photography and image processing, POSAS and VSS. Digital photography and analysis was more reliable than POSAS and VSS. Assessment of scar height was significantly more reliable when using a 3D scanner versus VSS and POSAS. The 3D scanner and mold-cast techniques also offered an additional benefit of providing an absolute value of scar height relative to the surrounding tissue. Intra-user reliability for all mechanical tests was moderate to good. Inter-user reliability was greater when using the BTC-2000? and ballistometer® versus the DTM®. All quantitative measurements took less than 90 s for collection, with the exception of the mold/cast technique.ConclusionNon-invasive instruments allow scar properties to be quantitatively assessed with high sensitivity and as a function of time and/or treatment without the need for biopsy collection. Overall, the reliability of scar assessments was significantly improved when quantitative instruments were utilized versus scar scales. Quantitative assessment of color and biomechanics were swift, requiring less than 90 s per measurement while assessments of texture and height required additional analysis time after collection. With proper training of clinical staff and well-defined protocols for measurement collection, reliable, quantitative assessments of scar properties can be collected with little disruption to the clinical workflow.  相似文献   
59.
Journal of Community Health - While human papilloma virus (HPV) vaccinations and Pap smear screenings are known to improve the survival rates and incidence of cervical cancer, refugee populations...  相似文献   
60.
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