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   1162篇
  免费   78篇
  国内免费   18篇
耳鼻咽喉   10篇
儿科学   50篇
妇产科学   34篇
基础医学   65篇
口腔科学   8篇
临床医学   67篇
内科学   463篇
皮肤病学   15篇
神经病学   50篇
特种医学   62篇
外科学   190篇
综合类   26篇
预防医学   49篇
眼科学   14篇
药学   50篇
肿瘤学   105篇
  2021年   16篇
  2020年   11篇
  2019年   12篇
  2018年   21篇
  2017年   8篇
  2016年   7篇
  2015年   18篇
  2014年   20篇
  2013年   29篇
  2012年   43篇
  2011年   50篇
  2010年   41篇
  2009年   30篇
  2008年   59篇
  2007年   49篇
  2006年   40篇
  2005年   51篇
  2004年   56篇
  2003年   48篇
  2002年   40篇
  2001年   33篇
  2000年   38篇
  1999年   29篇
  1998年   26篇
  1997年   17篇
  1996年   27篇
  1995年   18篇
  1994年   11篇
  1992年   25篇
  1991年   29篇
  1990年   37篇
  1989年   43篇
  1988年   33篇
  1987年   19篇
  1986年   16篇
  1985年   25篇
  1984年   22篇
  1983年   15篇
  1982年   7篇
  1981年   9篇
  1980年   8篇
  1978年   20篇
  1977年   8篇
  1976年   7篇
  1975年   14篇
  1973年   6篇
  1971年   10篇
  1970年   6篇
  1969年   5篇
  1965年   5篇
排序方式: 共有1258条查询结果,搜索用时 15 毫秒
51.
52.
Objective. We examined ethnic differences in self-reported functional status in a rural, population-based sample in North Carolina. Methods. Data from 1,197 African-American and Caucasian participants, aged 45 and older, in the Johnston County Osteoarthritis Project were analyzed using multiple logistic regression to examine ethnic differences in difficulty performing tasks of the Health Assessment Questionnaire (HAQ) and in risk factor profiles associated with difficulty. Results. Forty-three percent reported difficulty in one or more HAQ tasks. African-Americans were more likely than Caucasians to report difficulty performing 3 tasks (P < 0.04); these differences were minimal after adjustment for confounders. For some tasks, risk factor profiles included body mass index in African-Americans only, and age and female gender more often in Caucasians. Low educational attainment was part of the risk factor profile for walking in African-Americans. Conclusions. Differences in proportions of African-Americans and Caucasians reporting difficulty in performance of HAQ tasks were minimal, but risk factor profiles for difficulty appeared to vary by ethnicity.  相似文献   
53.
Objective. To examine the association between selfreported knee pain and radiographic features of osteoarthritis (OA) of the knee. Methods. A sample of participants in the Baltimore Longitudinal Study of Aging (452 Caucasian males and 223 Caucasian females) completed questionnaires and underwent a standing radiograph of both knees at the same biennial visit between 1984 and 1989. Radiographs were interpreted using both the Kellgren-Lawrence and individual features scales. Odds ratios were calculated for the association of radiographic features with knee pain after adjustment for age, sex, and body mass index. Results. Overall, 156 (23%) persons reported ever having knee pain, and 104 (15%) reported current knee pain (within the previous year). Both ever knee pain and current knee pain were significantly associated with the presence of definite knee OA (Kellgren-Lawrence grade ≥2) and with the presence of all individual features. There was a direct relationship between all measures of severity of radiographic OA and knee pain. Conclusion. These data demonstrate that radiographic features of knee OA are significantly associated with knee pain. The data also support the continued use of the Kellgren-Lawrence grading scale for defining knee OA in population studies.  相似文献   
54.
The course of 81 patients with systemic lupus erythematosus (SLE) who had sera tested for antibody to extractable nuclear antigen (ENA) was studied to determine the effect of the presence of antiENA antibody on survivorship. There were no differences in percent survival between the patients with and without antibody to ENA or those with and without antibody to the ribonucleoprotein (RNP) component of ENA. We conclude that there is no prognostic advantage to the presence of either antiENA or antiRNP antibody in patients with SLE.  相似文献   
55.
56.
57.
OBJECTIVES: To determine the relationship between prevalent vertebral deformities and the risk of mortality and hospitalization in older women with low bone mass. DESIGN: A prospective cohort study. SETTING: Eleven clinical centers in the United States. PARTICIPANTS: A total of 6459 community-dwelling women with low bone mass aged 55 to 81 participated in the Fracture Intervention Trial (FIT), a multicenter clinical trial of alendronate that enrolled women into one of two study arms based solely on the presence or absence of existing radiographic vertebral deformities. There were 2027 women with at least one vertebral deformity enrolled in the vertebral fracture arm of FIT and followed prospectively for an average of 2.9 years, whereas 4432 women with no vertebral deformity were enrolled in the clinical fracture arm of FIT and followed prospectively for an average of 4.2 years. MEASUREMENTS: Determination of prevalent vertebral deformities on baseline lateral thoracic and lumbar spine radiographs was made at the coordinating center using a combination of radiographic morphometry by digitization and semiquantitative radiologic interpretation. Deaths were confirmed by obtaining copies of original death certificates of all participants who died. Episodes of hospitalization were captured through adverse event reporting; hospitalizations resulting solely from adverse events containing the words "fracture" or "trauma" were excluded from the analyses. RESULTS: During the follow-up period, 122 women died, and 1676 women were hospitalized on at least one occasion for reasons not related solely to fracture. Compared with women without prevalent vertebral deformities, those women with prevalent deformities had higher risks of mortality (age- and treatment assignment-adjusted relative risk 1.60, 95% confidence interval (CI), 1.10-2.32) and hospitalization (age- and treatment assignment-adjusted relative risk 1.18, 95% CI, 1.06-1.31). In addition, further adjustment for other factors, including smoking status, physical activity, hypertension, coronary heart disease, obstructive lung disease, any fracture since the age of 50, health status, total hip BMD, and body mass index did not alter the association between prevalent vertebral deformities and risk of mortality substantially (multivariate relative risk 1.49, 95% CI, 1.05-2.21). Adjustment for all these factors and diabetes also did not change the relationship between prevalent vertebral deformities and hospitalization (multivariate relative risk 1.14, 95% CI, 1.02-1.27). Rates of mortality and hospitalization increased with increasing number of prevalent vertebral deformities (tests for trend P < .01). CONCLUSIONS: Prevalent vertebral deformities in older women with low bone mass are associated with increased risks of mortality and hospitalization. Only a portion of this increased risk was explained by other known predictors of these outcomes.  相似文献   
58.
The recognition of phonemes in consonant-vowel-consonant words, presented in speech-shaped random noise, was measured as a function of signal to noise ratio (S/N) in 10 normally hearing adults and 10 successful adult users of the Nucleus cochlear implant. Optimal scores (measured at a S/N of +25 dB) were 98% for the average normal subject and 42% for the average implantee. Phoneme recognition threshold was defined as the S/N at which the phoneme recognition score fell to 50% of its optimal value. This threshold was -2 dB for the average normal subject and +9 dB for the average implantee. Application of a digital noise suppression algorithm (INTEL) to the mixed speech plus noise signal had no effect on the optimal phoneme recognition score of either group or on the phoneme recognition threshold of the normal group. It did, however, improve the phoneme recognition threshold of the implant group by an average of 4 to 5 dB. These findings illustrate the noise susceptibility of Nucleus cochlear implant users and suggest that single-channel digital noise reduction techniques may offer some relief from this problem.  相似文献   
59.
Prior studies have suggested that pre-irradiation methotrexate (MTX)-based chemotherapy improves duration of response and survival in primary central nervous system lymphoma (PCNSL). To circumvent the potential emergence of drug resistance, we combined high-dose MTX with agents highly active against systemic lymphoma. Patients received three week cycles of CHOD (cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, and vincristine 1.4 mg/m2 [2 mg maximum] on day 1; dexamethasone 10 mg/m2 days 1–5), and MTX (3.5 gm/m2) with leucovorin rescue on day 8 (or on recovery from the CHOD nadir). Whole brain irradiation (WBRT) was planned after at least three cycles. Eighteen patients were treated. Complete responses were seen in eleven patients, and partial responses in three. Four progressed during therapy, three succumbing to progressive disease and one subsequently responding to WBRT Response duration was 37.5 months in those responding to therapy. The time to progression for all eighteen patients was 19.5 months. Medial survival was 25.5 months. Disease-free survival was 50% at 38 months in MCHOD responders. Grade 3 or 4 myelotoxicity was seen in 19 of 50 cycles. There were three instances of neutropenic fever, three of azotemia, two of deep vein thrombosis, and one each of community-acquired pneumonia, intracranial hemorrhage, superior vena cava syndrome, and hepatotoxicity. Late radiation-related toxicities were seen in two patients. Pre-irradiation MCHOD has activity against PCNSL, but appears to be no better than MTX monotherapy and has greater toxicity.  相似文献   
60.
Seven genotypic female (46,XX) patients with congenital adrenal hyperplasia, four reared as girls and three reared as boys were evaluated at 16–26 years of age with psychological interviews and testing. A small penis in the three young men produced a practical and psychological barrier that severely injured their personality. In spite of some degree of pre-adolescent tomboyism and a somewhat injured body image, the girls adjusted to their feminine gender indentity. It is concluded that in cases of both early and late diagnosis, the genotypic female sex should be prefered.Abbreviation IQ intelligence  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