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   1664篇
  免费   121篇
  国内免费   11篇
耳鼻咽喉   1篇
儿科学   117篇
妇产科学   15篇
基础医学   127篇
口腔科学   42篇
临床医学   250篇
内科学   414篇
皮肤病学   15篇
神经病学   44篇
特种医学   261篇
外科学   209篇
综合类   38篇
预防医学   94篇
眼科学   14篇
药学   69篇
  1篇
肿瘤学   85篇
  2021年   9篇
  2020年   8篇
  2019年   12篇
  2018年   17篇
  2017年   18篇
  2016年   16篇
  2015年   35篇
  2014年   36篇
  2013年   44篇
  2012年   60篇
  2011年   53篇
  2010年   62篇
  2009年   77篇
  2008年   52篇
  2007年   43篇
  2006年   44篇
  2005年   34篇
  2004年   37篇
  2003年   38篇
  2002年   40篇
  2001年   33篇
  2000年   27篇
  1999年   42篇
  1998年   89篇
  1997年   89篇
  1996年   94篇
  1995年   65篇
  1994年   57篇
  1993年   49篇
  1992年   32篇
  1991年   34篇
  1990年   24篇
  1989年   55篇
  1988年   45篇
  1987年   48篇
  1986年   33篇
  1985年   43篇
  1984年   23篇
  1983年   22篇
  1982年   17篇
  1981年   18篇
  1980年   11篇
  1979年   13篇
  1978年   7篇
  1977年   10篇
  1976年   16篇
  1975年   12篇
  1970年   5篇
  1968年   5篇
  1966年   5篇
排序方式: 共有1796条查询结果,搜索用时 15 毫秒
21.
BACKGROUND: This study sought to characterize the variables that predict postoperative prostate-specific antigen doubling time (PSADT) and biochemical recurrence time (RT) in patients who have failed radical prostatectomy (RP). METHODS: A total of 477 patients underwent RP at our institution for clinically localized prostate cancer. Of these patients, 64 (13.4%) demonstrated evidence of postoperative biochemical failure. PSADT and biochemical RT were calculated for all patients. PSADT and RT were correlated with clinical variables including preoperative PSA level, patient age, race, prostate weight and with pathologic characteristics of the operative specimen using uni- and multivariate analyses. In addition, PSADT and RT were also correlated with each other and with the time to postoperative adjuvant therapy. RESULTS: Median postoperative PSADT for patients who recurred after radical prostatectomy was 9.7 months. Postoperative PSADT was predicted by lymph node involvement (p < 0.001) and Gleason grade (p = 0.06). Rapid PSADT also correlated with institution of postoperative adjuvant therapy (p = 0.003). Median biochemical RT for all patients was 6.7 months. Gleason grade and pathologic stage were found to be predictors of RT (p < 0.002). Postoperative PSADT did not correlate with RT (r = 0.08; p = 0.53). PSADT and RT were not different between Caucasian- versus African-Americans. CONCLUSIONS: These results serve to better characterize our cohort of patients who have evidence of biochemical recurrence after radical prostatectomy. Aggressiveness of recurrent disease (i.e. PSADT) seems to be predicted by lymph node involvement and higher pathologic grade. Furthermore, the lack of correlation of RT and PSADT suggests that early recurrences are not necessarily aggressive tumors: conversely, aggressive recurrences may occur at any point in the postoperative period. This information may aid in the postoperative treatment of recurrent disease and help to better define those patients who are at higher risk for developing clinical recurrence and who would benefit from greater vigilance during the postoperative period.  相似文献   
22.
There are a limited number of epidemiological studies that have focused on trauma exposure and prevalence of posttraumatic stress disorder (PTSD) in representative general population samples of adolescents, especially outside of the United States. We therefore aimed to assess the lifetime prevalence of traumatic events (TEs) and current prevalence of PTSD, and to examine demographic risk factors for TEs and PTSD in a representative sample of adolescents. Data were collected by a school survey among a sample of 6,787 9th‐grade students in Switzerland. Roughly 56% of the adolescents (females 56.6%; males 55.7%) reported having experienced at least 1 TE. Non‐Swiss nationality (OR = 1.80), not living with both biological parents (OR = 1.64), and lower parental education (OR = 1.18) were associated with a higher risk of trauma exposure. The current prevalence of PTSD according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM‐IV‐TR; American Psychiatric Association, 2000) criteria was 4.2% (females 6.2%; males 2.4%). Female gender (OR = 2.70), not living with both biological parents (OR = 1.47), lower parental education (OR = 1.51), and exposure to multiple TEs (OR = 9.56) were significant risk factors for PTSD. Results suggest considerably high rates of TEs and PTSD among adolescents. Intervention efforts must be intensified to reduce trauma exposure and treat PTSD.  相似文献   
23.
We have used the long-term bone marrow culture (LTBMC) system to analyze hematopoiesis in three patients with dyskeratosis congenita (DC), two of whom had aplastic anemia, and the third had a normal blood count (apart from mild macrocytosis) and normal BM cellularity. Hematopoiesis was severely defective in all three patients, as measured by a low incidence of colony-forming cells and a low level of hematopoiesis in LTBMC. The function of the marrow stroma was normal in its ability to support the growth of hematopoietic progenitors from normal marrows seeded onto them in all three cases, but the generation of hematopoietic progenitors from patients marrow cells inoculated onto normal stromas was reduced, thus suggesting the defect to be of stem cell origin. The parents and unaffected brother of one of the families have also been studied in LTBMC and all showed normal hematopoietic and stromal cell function. From this study we speculate that there are some similarities between DC and the defect in the W/Wv mouse.  相似文献   
24.
25.

Background

The effectiveness of diclofenac versus paracetamol in primary care patients with pain caused by knee osteoarthritis is unclear.

Aim

To assess the effectiveness of diclofenac compared with paracetamol over a period of 2, 4, and 12 weeks in patients with knee osteoarthritis.

Design and setting

Randomised controlled trial in general practice.

Method

There were 104 patients included in the study, they were aged ≥45 years consulting their GP with knee pain caused by knee osteoarthritis. Patients were randomly allocated to diclofenac (n = 52) or paracetamol (n = 52) for at least 2 weeks. Primary outcomes were daily knee pain severity, and knee pain and function measured with the Knee Injury and Osteoarthritis Outcome Score (KOOS).

Results

Over a period of 2- and 4-weeks follow-up, no significant difference in daily knee pain was found between the patient groups: estimated differences of 0.5 (95% CI = −0.2 to 1.3) and −0.2 (95% CI = −1.0 to 0.7), respectively. Over the 12-weeks follow-up, no significant differences were found between both groups for KOOS pain: estimated difference of −2.8 (95% CI = −10.7 to 5.1) and KOOS function of −2.7 (−10.6 to 5.0).

Conclusion

Over a period of 2- and 4-weeks follow-up no significant difference in daily measured knee pain severity was found between primary care patients with knee osteoarthritis taking paracetamol or diclofenac. Also, over a period of 12-weeks follow-up no significant differences were found regarding KOOS pain and KOOS function between both groups. Patients more frequently reported minor adverse events after taking diclofenac (64%) than paracetamol (46%).  相似文献   
26.
OBJECTIVE: To examine whether promoter polymorphisms associated with variation in interleukin-10 (IL-10) production are relevant to the development of rheumatoid arthritis (RA) or Felty's syndrome (FS). METHODS: DNA was obtained from 44 FS patients, 117 RA patients and 295 controls. The promoter region between -533 and - 1120 was amplified by polymerase chain reaction, and polymorphisms detected by restriction enzyme digest or sequence-specific oligonucleotide probing. RESULTS: We found no significant difference in allele or haplotype frequencies between the groups. CONCLUSION: There is no association between FS or RA and these recently identified IL-10 promoter polymorphisms. Other genetic or environmental factors could explain the alterations in IL-10 levels seen in these conditions.   相似文献   
27.
Peripheral arterial disease: identification and implications   总被引:12,自引:0,他引:12  
Peripheral arterial disease (PAD) is most commonly a manifestation of systemic atherosclerosis in which the arterial lumen of the lower extremities becomes progressively occluded by atherosclerotic plaque. Patients with PAD are at triple the risk of all-cause mortality and at more than 6 times the risk of death from coronary heart disease as those without the disease, yet PAD is probably the most underdiagnosed and least aggressively managed atherosclerotic disease. In the diagnosis of PAD, a detailed history and physical examination are extremely important, although limited by a lack of consistent sensitivity and specificity. Other office-based noninvasive tests, including the ankle-brachial index, can be easily performed to confirm the diagnosis and help stratify the risk. The ankle-brachial index correlates well with disease severity and functional symptoms and can also be used to assess disease progression and to predict cardiovascular and cerebrovascular mortality. Once diagnosed, risk factor modification, symptomatic relief, and secondary prevention strategies with antiplatelet agents form the core of medical management of PAD.  相似文献   
28.
29.
30.
A statistical analysis of murine stem cell suicide techniques   总被引:1,自引:0,他引:1  
Quesenberry  PJ; Stanley  K 《Blood》1980,56(6):1000-1005
The clinical application of soft agar cloning techniques for granulocyte-macrophage stem cells (CFU-C) has resulted in a number of contradictory reports that may in part be due to an inadequate data base. Growth of murine CFU-C is more reproducible and less variable than that of human CFU-C. We utilized in vivo hydroxyurea suicide of murine marrow CFU-C to address the question of how many experiments are needed to detect a specific difference with a p of less than 0.05. In 66 experiments the mean marrow CFU-C hydroxyurea kill was 23.3%; 6-9 separate experiments were necessary to detaect differences of 25%-30%. In order to be sure that a 25%-30% difference is not present, 15-21 experiments were required. Using a Dec-20 computer, 1000 samples of sample size 3, 4, or 10 were drawn from the 66 experiments; it was found that with 3 experiments and a true value of 23%, the actually observed value was below 10%, 17% of the time, and was over 40% in 10% of the samplings. In a smaller number of experiments similar results were obtained analyzing 3HTdR suicide of pluripotent stem cells and CFU- C. These data could provide a base from which to judge the validity of studies utilizing the CFU-C technique.  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