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   1970篇
  免费   105篇
  国内免费   34篇
耳鼻咽喉   26篇
儿科学   84篇
妇产科学   25篇
基础医学   184篇
口腔科学   36篇
临床医学   183篇
内科学   497篇
皮肤病学   118篇
神经病学   81篇
特种医学   225篇
外科学   246篇
综合类   37篇
预防医学   140篇
眼科学   14篇
药学   130篇
中国医学   3篇
肿瘤学   80篇
  2021年   18篇
  2019年   30篇
  2018年   24篇
  2017年   17篇
  2016年   26篇
  2015年   33篇
  2014年   40篇
  2013年   105篇
  2012年   51篇
  2011年   47篇
  2010年   64篇
  2009年   75篇
  2008年   69篇
  2007年   56篇
  2006年   64篇
  2005年   66篇
  2004年   43篇
  2003年   49篇
  2002年   43篇
  2001年   42篇
  2000年   31篇
  1999年   34篇
  1998年   89篇
  1997年   85篇
  1996年   86篇
  1995年   54篇
  1994年   69篇
  1993年   57篇
  1992年   24篇
  1991年   23篇
  1990年   37篇
  1989年   55篇
  1988年   54篇
  1987年   47篇
  1986年   34篇
  1985年   37篇
  1984年   24篇
  1983年   15篇
  1982年   26篇
  1981年   18篇
  1980年   14篇
  1979年   18篇
  1978年   16篇
  1977年   16篇
  1976年   17篇
  1975年   15篇
  1974年   10篇
  1973年   16篇
  1972年   16篇
  1971年   10篇
排序方式: 共有2109条查询结果,搜索用时 15 毫秒
41.
OBJECTIVE: To determine whether in the previous National Surgical Adjuvant Breast and Bowel Project (NSABP) studies of node-negative breast cancer there were either cohorts of patients with a prognosis favorable enough to preclude using systemic therapy or subsets of patients who failed to benefit from the treatments. DESIGN: Randomized clinical trials with stratification after surgery. SETTING: NSABP trials at institutions in the United States and Canada. PATIENTS: Data were collected on 731 eligible patients (Protocol B-13) with estrogen-receptor-negative tumors who randomly received either no therapy after surgery or sequential methotrexate and fluorouracil (M----F) followed by leucovorin. Data were also collected on 2834 patients (Protocol B-14) with estrogen-receptor-positive tumors who randomly received either placebo or tamoxifen treatment. The percentage of patients surviving disease-free was determined through 4 years of follow-up using life-table estimates. INTERVENTIONS: Protocol B-13 patients received 12 courses of M----F given intravenously on days 1 and 8 every 4 weeks. Leucovorin therapy was begun 24 hours after M----F administration. Protocol B-14 patients received 5-year treatment with either tamoxifen (10 mg twice daily by mouth) or placebo. RESULTS: When the outcome of untreated patients in either trial was related to the stratification variables, women were found to have a disease-free survival of less than 80% through 4 years of follow-up. This percentage is apt to decrease because the probability of treatment failure increases with time. In both trials, all subsets of women benefited from M----F or tamoxifen therapy. CONCLUSIONS: The disease-free survival of all cohorts of node-negative patients with estrogen-receptor-negative or estrogen-receptor-positive tumors was poor enough to justify systemic treatment. The benefits of the therapies used are insufficient to eliminate the need for assessing putatively better regimens.  相似文献   
42.
43.
Summary We have presented an unusual case of benign lymphoid hyperplasia, which manifested as a cecal deformity in a 15-year-old boy. The clinical manifestation may have been related to partial occlusion of the appendiceal orifice. In future cases of benign lymphoid hyperplasia, colonoscopy may be diagnostic, and if it is used for continuing observation, may avert unnecessary surgical procedures in children and young adults.  相似文献   
44.
Exposure of the distal esophageal mucosa to acid gastric juice was quantitated by 24-hr pH monitoring in 100 individuals and was correlated with morphologic data derived from esophageal biopsies. The degree of acid exposure to the distal esophagus correlated directly with increases in both relative and absolute length of the subepithelial papillae and to relative basal zone hyperplasia. Both papillary length and basal zone hyperplasia decreased after antireflux surgery had reduced acid exposure to normal. Reflux in the recumbent position resulted in prolonged exposure of the mucosa to acid because of poor acid clearing from the esophagus. This caused longer papillae than did upright reflux, where there were more frequent reflux episodes, but with rapid acid clearance. The presence of a hiatal hernia was associated with longer papilae, lower DES pressure, increased reflux frequency, and prolonged recumbent acid clearance. Twenty-four hour pH monitoring correlated better with papillary length than did symptoms or other clinical measures of gastroesophageal reflux.  相似文献   
45.
Methods:We report a prospective, consecutive case series of 128 outpatient TLHs performed for benign gynecologic conditions in a tertiary care center.Results:Of the 295 women scheduled for a TLH, 151 (51%) were attempted as an outpatient procedure. A total of 128 women (85%) were actually discharged home the day of their surgery. The most common reasons for admission the same day were urinary retention (19%) and nausea (15%). Indications for hysterectomy were mainly leiomyomas (62%), menorrhagia (24%), and pelvic pain (9%). Endometriosis and adhesions were found in 23% and 25% of the cases, respectively. Mean estimated blood loss was 56 mL and mean uterus weight was 215 g, with the heaviest uterus weighing 841 g. Unplanned consultation and readmission were infrequent, occurring in 3.1% and 0.8% of cases, respectively, in the first 72 hours. At 3 months, unplanned consultation, complication, and readmission had occurred in a similar proportion of inpatient and outpatient TLHs (17.2%, 12.5%, and 4.7% versus 18.1%, 12.7%, and 5.4%, respectively). In a logistic regression model, uterus weight, presence of adhesions or endometriosis, and duration of the operation were not associated with adverse outcomes.Conclusion:Same-day discharge is a feasible and safe option for carefully selected patients who undergo an uncomplicated TLH, even in the presence of leiomyomas, severe adhesions, or endometriosis.  相似文献   
46.
47.
48.
Abstract

Production of monoclonal antibodies against hCG has been studied using hCG as the antigen. This study reports the successful isolation of hybrid clones secreting monoclonal antibodies specific for hCG with an affinity constant higher than 1010M?l. Of 23 fusions, only 17 fusions have produced positive clones which secrete antibodies giving high levels of binding with l25I-labelled hCG in the supernatant. Finally, 6 different monoclonal antibodies have been isolated; 4 of them, specific for the β-subunit, with a Ka approximately 1.1–4.0 ± 1011M?1 and 2 others, specific for the α-subunit, presenting an affinity of 2.5 ± 1010M?l. When the antibodies specific for the β-subunit are used, specific and highly sensitive radioim-munoassays are obtained after only 3 hrs of incubation. Using iodinated monoclonal antibodies specific for the α-subunit and tubes coated with antibodies against the β-subunit, we have developped sensitive immunoradiometric assays.  相似文献   
49.
The epidemiological status of HCV in Europe, and in particular in Mediterranean countries, is continuously evolving. The genotype distribution is related to improvement of healthcare conditions, expansion of intravenous drug use and immigration. We review and characterize the epidemiology of the distribution of HCV genotypes within Calabria, an area of Southern Italy. We focus on the pattern of distinct HCV genotype changes over the last 16 years; particularly subtype 1b and genotype 4. We collected data by evaluating a hospital-based cohort of chronic hepatitis C patients; in addition, we report an update including new patients enrolled during last eight months.  相似文献   
50.
Rehabilitation is influenced by the individual's abilities and resources and extent to which they are used. This study explored self-actualization (capacity to maximize use of one's abilities and resources) in 37 individuals attending in-patient rehabilitation following a stroke by (1) comparing the level of self-actualization of the participants to the level of self-actualization of 562 healthy community-dwelling individuals without stroke; (2) assessing changes in the level of self-actualization during rehabilitation (admission vs. discharge); and (3) exploring the relationships between self-actualization and changes in functional independence during rehabilitation, length of stay in the rehabilitation unit and change in living environment at discharge. Self-actualization was assessed with the measure of actualization of potential. The results showed that individuals with stroke had significantly lower self-actualization levels (P<0.001) than community-dwelling individuals without stroke. Self-actualization levels remained stable during rehabilitation (P=0.07). No significant relationships were found between self-actualization and changes in functional independence (P=0.36), length of stay (P=0.82) or change in living environment (P=0.65). This study suggests that many individuals with stroke are poorly actualized and self-actualization levels do not improve during rehabilitation. Further studies are needed to explore the relationship between self-actualization and other outcome measures in poststroke rehabilitation such as depressive symptoms or social participation.  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