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   956篇
  免费   137篇
  国内免费   10篇
耳鼻咽喉   15篇
儿科学   93篇
妇产科学   13篇
基础医学   83篇
口腔科学   39篇
临床医学   147篇
内科学   229篇
皮肤病学   9篇
神经病学   38篇
特种医学   162篇
外科学   127篇
综合类   34篇
预防医学   39篇
眼科学   1篇
药学   21篇
中国医学   5篇
肿瘤学   48篇
  2022年   3篇
  2021年   11篇
  2020年   6篇
  2019年   6篇
  2018年   35篇
  2017年   42篇
  2016年   37篇
  2015年   34篇
  2014年   36篇
  2013年   61篇
  2012年   29篇
  2011年   26篇
  2010年   59篇
  2009年   54篇
  2008年   31篇
  2007年   28篇
  2006年   19篇
  2005年   16篇
  2004年   13篇
  2003年   13篇
  2002年   8篇
  2001年   17篇
  2000年   8篇
  1999年   6篇
  1998年   59篇
  1997年   53篇
  1996年   55篇
  1995年   49篇
  1994年   28篇
  1993年   40篇
  1992年   16篇
  1991年   18篇
  1990年   19篇
  1989年   15篇
  1988年   24篇
  1987年   21篇
  1986年   15篇
  1985年   10篇
  1984年   12篇
  1983年   16篇
  1982年   3篇
  1981年   16篇
  1980年   8篇
  1979年   1篇
  1978年   2篇
  1977年   10篇
  1976年   9篇
  1975年   3篇
  1971年   1篇
  1938年   1篇
排序方式: 共有1103条查询结果,搜索用时 15 毫秒
991.
By April 1995, 302 cases of vertically acquired HIV infection had been reported through the British Paediatric Association Surveillance Unit. Over 50% of these children had developed an AIDS indicator disease, including nine malignancies (seven cases of non-Hodgkin's lymphoma (NHL) and two of Kaposi's sarcoma). There were two other malignancies that were not AIDS indicator diseases. In children less than 5 years of age the incidence of NHL was approximately 2500 times greater than expected in the UK child population. Three children presented with NHL as their AIDS indicator disease and four developed NHL at a median of 14 (range 10-19) months after the initial diagnosis of AIDS. Six of the seven children died at a median of 6.5 (range 2-14) months after the diagnosis of NHL. The seventh child responded to treatment and is alive nearly four years later. Histology was available in five cases, of which four were of B cell and one of T cell origin. Epstein-Barr virus was detected in all three patients with NHL where it was sought; all had B cell lymphomas. Although comparatively rare, malignancies occur in children infected with HIV and may be the presenting illness. Paediatricians now need to consider HIV infection as a predisposing cause of childhood cancer, especially NHL.  相似文献   
992.
OBJECTIVES: To determine the incidence of insulin dependent diabetes mellitus (IDDM) among children aged up to 16 years residing in the city of Karachi, Pakistan, during the five years from 1989 to 1993. DESIGN: Retrospective study of incidence using hospital and clinic records. SETTING: The city of Karachi, Pakistan. SUBJECTS: Children satisfying standard criteria for the diagnosis of IDDM, attending treatment facilities for the first time during the study period. MAIN OUTCOME MEASURES: The incidence of IDDM in this population and its variation by age and sex. RESULTS: The incidence of IDDM in this population is 1.02/100000 per year, which is one of the lowest incidence rates yet reported. CONCLUSIONS: The very low incidence of IDDM, contrasted with the substantially higher incidence among migrants, supports the view that environmental factors are the major determinants of variations in the incidence of this condition between populations.  相似文献   
993.
Thirty-nine patients undergoing either Silastictrade mark ring vertical banded gastroplasty (SRVG, n = 23) or Roux-en-Y gastrointestinal bypass (RGB, n = 16) over a 1-year period were analyzed retrospectively. Weight loss averaged 40 kg (89 lb). Clinical diabetes mellitus was markedly improved in seven out of nine patients (p = 0.023). Shortness of breath resolved in all 26 patients who had this condition preoperatively (p < 0.001). Orthopedic problems, high blood pressure, and self-assessment of general health and quality of life were also dramatically improved. We conclude that bariatric surgery serves as an effective method to alleviate a multitude of conditions associated with morbid obesity.  相似文献   
994.
Preoperative autologous blood donation for elective surgery patients at university hospitals was underused in the past. More recently, national educational efforts have been made. To test the impact of local surgeon interviews and education, in 1988 the same local educational program was instituted at three university hospitals; three community hospitals were used as controls. Donation by appropriate patients of interviewed surgeons (elective surgery, crossmatch recommended, no contraindications to donation) increased from 24 percent (44/180) to 40 percent (88/222) (p = 0.002) and 15 percent (21/143) to 32 percent (41/127) (p = 0.001) at two university hospitals where the investigator-educators were on site, but not at the three community hospitals. Between 1987 and 1989, donation rates at all six hospitals remained low among patients for whom autologous donation was (probably) less appropriate. Donation rates for type and screen procedures were 3.0 percent (131/4587) in 1987 and 3.0 percent (199/6606) in 1989 (p = 0.67). Donation rates for "no blood order" procedures were 0.2 percent (15/9429) in 1987 and 0.1 percent (9/11,239) in 1989 (p = 0.14). It can be concluded that appropriate autologous blood donations increased at university hospitals where surgeons were individually interviewed and educated by an investigator on site. However, despite this increase, apparently eligible elective surgery patients in 1989 still failed to donate. This situation deserves additional investigation.  相似文献   
995.
Balance of cell proliferation and apoptosis in breast carcinogenesis   总被引:6,自引:0,他引:6  
We determined the mitotic and apoptotic index through the spectrum of preinvasive ductal breast lesions to invasive carcinoma in search of disturbances in the proliferation/cell death balance in breast carcinogenesis. Seventytwo pure preinvasive ductal breast lesions (without invasive carcinoma) and 103 invasive breast carcinomas were used. The numbers of mitotic and apoptotic cells were microscopically counted in hematoxylin and eosin stained sections (MI and Al, respectively), and the ratio of the values of MI and AI was calculated for each individual case (M/A index).A distinction was made between well differentiated and poorly differentiated breast lesions, based on histological type and nuclear grade, to arrive at two plausible progression models for breast carcinogenesis. For the well differentiated breast lesions, the MI was rather equal for hyperplasias and well differentiated DCIS, but increased 6fold from DCIS to well differentiated invasive carcinoma. The AI remained in the same range, resulting in a 4fold increase of the M/A index. For the poorly differentiated breast lesions, a significant increase in MI and AI was found from hyperplasia to poorly differentiated DCIS. From DCIS to poorly differentiated invasive carcinoma, the MI increased significantly and the AI decreased 2fold (n.s.), resulting in a 2.5fold significant increase of the M/A index.In conclusion, the net increase of the number of cells in the transition from well differentiated preinvasive to well differentiated invasive carcinoma is accompanied by an increase of cell proliferation rather than decrease in apoptosis, suggesting that in these lesions, proliferation related mechanisms are most important in carcinogenesis and progression. In contrast, in poorly differentiated breast lesions, decreased apoptosis seems to be also important in carcinogenesis and progression. At present, we are gathering patients with invasive breast cancer who had a previous biopsy with a preinvasive lesion to obtain further more direct evidence for this hypothesis.  相似文献   
996.
A total of 21 families with complete sets of triplets, born within 200 km of Stockholm, were invited to participate in a follow-up study with the aim of assessing the physical and mental development of their triplets at 4-6 years of age. Four families declined to participate in the study and thus the study group consisted of 17 sets of triplets who were born at 33-36 gestational weeks from 1986 to 1989. Mean birth weight was 2104g (range 1310-2670g) for the boys and 1882g (range 1290-2590g) for the girls. At birth, none of the 51 triplets showed any malformations. No asphyxia or other major complications were noted to have occurred at delivery. The children were examined in their homes with a neurological examination and the Griffiths mental development scales (GMDS). No major physical disabilities were found. In a group of triplets born small for dates, the total GMDS score and most of the subscale scores were significantly lower than for their siblings. In contrast to what has been found in singletons and twins, the differences in mental development between triplet boys and girls were not significant. On the whole, physical and mental development did not differ from what has been found in twins and singletons of the same age and with the same birth weight.  相似文献   
997.
998.
Plasma cytokine levels in necrotizing enterocolitis   总被引:2,自引:0,他引:2  
Plasma concentrations of tumour necrosis factor (TNF) and interleukin-6 (IL-6) were measured by ELISA in samples taken from 24 infants with necrotizing enterocolitis (NEC) between 0 and 306 h from diagnosis. TNF was detected (>10pg/ml) in 71% samples with a mean of 48pg/ml (95% CI 42 to 55 pg/ml) and did not vary with either time from diagnosis or severity of disease. IL-6 was raised during the first 48 h with a significant difference between stage II (mean 127 pg/ml, 95% CI 10 to 329 pg/ml) and stage HI (mean 3127 pg/ml, 95% CI 1809 to 4445 pg/ml, p = 0.001). Postoperative plasma IL-6 concentration fell to similar levels seen in stage II (mean 150 pg/ml, 95% CI 37 to 283 pg/ ml, p = 0.79). We conclude that plasma concentration of IL-6 rather than TNF reflects the clinical severity of necrotizing enterocolitis and that the relative level of these cytokines has important implications for the use of anti-cytokine therapy in NEC.  相似文献   
999.
Evidence of failure of organ system other than the gastrointestinal tract was reviewed in a series of 46 infants treated for necrotizing enterocolitis (NEC) at a regional combined medical and surgical neonatal unit. Respiratory failure was identified in 42 infants (91%), renal failure in 39 (85%), cardiovascular failure in 15 (33%) and hepatic failure in 7 (15%). The number of systems involved correlated with both severity of disease and outcome. Onset of failure in the above systems was closely related to the diagnosis of NEC and 29 cases predated the clinical onset. We conclude that NEC is part of a syndrome of multisystem failure and that this has important implications for the treatment of NEC.  相似文献   
1000.
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