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   1647篇
  免费   115篇
  国内免费   7篇
耳鼻咽喉   5篇
儿科学   127篇
妇产科学   55篇
基础医学   258篇
口腔科学   9篇
临床医学   96篇
内科学   242篇
皮肤病学   25篇
神经病学   109篇
特种医学   14篇
外科学   309篇
综合类   122篇
预防医学   84篇
眼科学   16篇
药学   143篇
中国医学   5篇
肿瘤学   150篇
  2023年   10篇
  2022年   20篇
  2021年   53篇
  2020年   26篇
  2019年   30篇
  2018年   35篇
  2017年   23篇
  2016年   31篇
  2015年   22篇
  2014年   34篇
  2013年   39篇
  2012年   78篇
  2011年   92篇
  2010年   64篇
  2009年   65篇
  2008年   71篇
  2007年   78篇
  2006年   61篇
  2005年   54篇
  2004年   37篇
  2003年   36篇
  2002年   54篇
  2001年   42篇
  2000年   23篇
  1999年   33篇
  1998年   11篇
  1997年   12篇
  1995年   17篇
  1994年   17篇
  1993年   16篇
  1992年   27篇
  1991年   36篇
  1990年   25篇
  1989年   32篇
  1988年   25篇
  1987年   22篇
  1986年   36篇
  1985年   18篇
  1984年   19篇
  1983年   17篇
  1982年   10篇
  1981年   9篇
  1979年   16篇
  1975年   15篇
  1974年   19篇
  1973年   12篇
  1972年   10篇
  1971年   13篇
  1970年   16篇
  1966年   10篇
排序方式: 共有1769条查询结果,搜索用时 15 毫秒
51.
Neonatal back-transport. Cost-effectiveness   总被引:1,自引:0,他引:1  
This study examines the cost-effectiveness of returning previously ill neonates to community hospitals after treatment in a tertiary center, a concept known as "back-transport." The authors compared the charges for medical care during convalescence of a group of back-transported infants (BT infants; n = 20) with a similar group of infants who remained in a tertiary center for convalescence (NT infants; n = 20). The total charges for convalescent care (inpatient plus transport charges) for 20 representative BT infants was $61,840, compared with $68,240 for 20 matched NT infants, an average savings of $320 per BT infant. The average daily bed charge and charges for laboratory tests and medications were significantly less for BT infants compared with NT infants, and these reductions offset the transport charges for BT infants. The authors conclude that back transport decreases the charges for medical care for most infants. Therefore, the decision to back-transport an individual infant usually can be based on factors other than cost.  相似文献   
52.
To investigate the neural network of overt speech production, event-related fMRI was performed in 9 young healthy adult volunteers. A clustered image acquisition technique was chosen to minimize speech-related movement artifacts. Functional images were acquired during the production of oral movements and of speech of increasing complexity (isolated vowel as well as monosyllabic and trisyllabic utterances). This imaging technique and behavioral task enabled depiction of the articulo-phonologic network of speech production from the supplementary motor area at the cranial end to the red nucleus at the caudal end. Speaking a single vowel and performing simple oral movements involved very similar activation of the cortical and subcortical motor systems. More complex, polysyllabic utterances were associated with additional activation in the bilateral cerebellum, reflecting increased demand on speech motor control, and additional activation in the bilateral temporal cortex, reflecting the stronger involvement of phonologic processing.  相似文献   
53.
Bose B  Gour RR  Motiwale L  Rao KV 《Chemotherapy》2006,52(4):210-214
BACKGROUND: Malachite green (MG), consisting of green crystals with a metallic lustre, is highly soluble in water, cytotoxic to various mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and possible exposure of human beings, MG poses a potential environmental health hazard. We have earlier reported the malignant transformation of Syrian hamster embryo (SHE) cells by MG. METHODS: Cell transformation assays were carried out as described in the literature. Western blotting and flow cytometry were carried out by standard methods. RESULTS: In this study, we have studied the role of all three isoforms of mitogen-activated protein (MAP) kinases, i.e. extracellular regulated kinases (ERKs), Jun N-terminal kinases (JNKs) and p38 kinase in the MG-transformed SHE fibroblasts compared to controls. Our results showed that transformed cells were associated with decreased expression of ERKs and JNKs as evidenced by Western blotting studies. However, the p38 MAP kinase was found to be upregulated. Flow cytometric DNA histogram analysis indicated an increase in the expression of S phase cells in the transformed cell line as compared to their control counterparts. CONCLUSIONS: The present studies indicate that decreased phosphoactive ERKs and JNKs and increased phosphoactive p38 kinase are associated with increased S phase cells during transformation of SHE cells by MG.  相似文献   
54.
55.
Reduced expression of PTEN correlates with breast cancer progression   总被引:27,自引:0,他引:27  
PTEN is a tumor-suppressor gene with phosphatase activity that is mutated in a variety of cancers. We analyzed a series of 34 invasive and 18 in situ breast cancers with known molecular status of the PTEN genotype using immunohistochemistry. Reduced PTEN protein expression was seen in 38% of invasive cancers and in 11% of in situ cancers. The frequency of reduced expression was highest in stage II and III cancers. Reduced expression also correlated with aneuploidy. In addition, in tumors with both in situ and invasive components, expression within the ductal carcinoma in situ portion tended to reflect the expression pattern of the invasive component. These data suggest that PTEN expression is frequently reduced in advanced breast cancers.  相似文献   
56.
57.
OBJECTIVES: To determine the prevalence and identify risk factors for iron deficiency and anemia in pregnant Ghanaian women from urban areas. METHODS: A cross-sectional study of 452 healthy pregnant women receiving prenatal care in Accra, Ghana, was conducted. A sociodemographic health questionnaire was performed and hematologic parameters were measured. Logistic regression methods were used to identify risk factors for anemia and iron status. RESULTS: Complete data were available for 428 women. Anemia (hemoglobin <11 g/dL) was present in 144 (34%), iron deficiency (ferritin < or =16 microg/L) in 69 (16%), and iron deficiency anemia in 32 (7.5%) women. The adjusted odds ratio (OR) for anemia was 3.4 and 9.8 if iron deficiency and malaria parasitemia were present, respectively; the OR was 0.6 if women were at > or =36 weeks of pregnancy. The adjusted OR for iron deficiency was 2.7 if women were at > or =36 weeks of pregnancy and 0.12 if they had sickle trait. CONCLUSION: Although anemia and iron deficiency remain substantial problems in pregnant Ghanaian women from urban areas, their prevalence is less than previously reported.  相似文献   
58.
59.
60.
PURPOSE OF REVIEW: The ductus arteriosus is a vessel that connects the pulmonary artery to the aorta and provides a pulmonary-to-systemic diversion during fetal life. In the vast majority of infants, the ductus arteriosus closes by 3 days of life. In some infants, especially preterm infants with lung disease, there is delayed closure of the ductus arteriosus. There has been controversy as to whether or when the ductus arteriosus should be closed by either pharmacologic or surgical methods. RECENT FINDINGS: There have been several epidemiologic studies describing an association between a patent ductus arteriosus and the development of morbidities, such as chronic lung disease. These associations have suggested to some that a causal relationship exists between patency of the ductus arteriosus and chronic lung disease and other morbidities. However, recent metaanalyses of randomized, controlled trials of the use of indomethacin for the prevention and treatment of the patent ductus arteriosus have not documented a decrease in the incidence of these morbidities after treatment, despite success in closure of the patent ductus arteriosus. SUMMARY: In preterm infants, patency of the ductus arteriosus may represent a normal physiologic adaptation to allow shunting from either systemic-to-pulmonary circulation (eg, in the first day of life) or from pulmonary-to-systemic circulation (eg, in the presence of severe lung disease). Therapies designed to close the ductus arteriosus are contraindicated in some settings and should not be considered a standard of care at any time until these therapies are proven to decrease long-term clinical morbidities in randomized, placebo-controlled trials.  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