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   3824篇
  免费   272篇
  国内免费   7篇
耳鼻咽喉   58篇
儿科学   96篇
妇产科学   52篇
基础医学   640篇
口腔科学   35篇
临床医学   339篇
内科学   918篇
皮肤病学   74篇
神经病学   300篇
特种医学   111篇
外科学   672篇
综合类   21篇
一般理论   1篇
预防医学   255篇
眼科学   24篇
药学   253篇
中国医学   6篇
肿瘤学   248篇
  2023年   16篇
  2022年   23篇
  2021年   61篇
  2020年   48篇
  2019年   61篇
  2018年   80篇
  2017年   59篇
  2016年   80篇
  2015年   68篇
  2014年   107篇
  2013年   155篇
  2012年   266篇
  2011年   278篇
  2010年   159篇
  2009年   149篇
  2008年   251篇
  2007年   257篇
  2006年   292篇
  2005年   245篇
  2004年   252篇
  2003年   232篇
  2002年   220篇
  2001年   32篇
  2000年   25篇
  1999年   35篇
  1998年   67篇
  1997年   43篇
  1996年   45篇
  1995年   41篇
  1994年   32篇
  1993年   26篇
  1992年   17篇
  1991年   22篇
  1990年   24篇
  1989年   20篇
  1988年   22篇
  1987年   16篇
  1986年   20篇
  1985年   22篇
  1984年   21篇
  1983年   15篇
  1982年   24篇
  1981年   22篇
  1980年   20篇
  1979年   13篇
  1978年   12篇
  1977年   11篇
  1975年   8篇
  1974年   8篇
  1973年   11篇
排序方式: 共有4103条查询结果,搜索用时 15 毫秒
101.
102.
103.
Hepatic colorectal metastases: methods of improving resectability   总被引:9,自引:0,他引:9  
Surgery is the best treatment modality for colorectal liver metastases. When initially unresectable, hepatic resection of metastases after downstaging by chemotherapy can provide a hope of long-term survival similar to that of primarily resected patients. Definitions of resectability have evolved with the emerging principle that if metastases can be completely resected regardless of their size and number,resection should be performed as the sole mean of achieving long-term survival.Specific surgical techniques can be combined to improve resectability. If the tumor is considered unresectable, recent developments make possible to render some tumors surgically resectable. Depending on the tumor size, number and location, neoadjuvant treatments, mainly chemotherapy, can be used, followed by resection. Resection may be contraindicated if the residual volume of liver is inadequate to avoid liver failure. This may be changed either by PVE or two-stage hepatectomy, both of which use the natural regenerative capacity of the liver. Local destructive therapies such as cryosurgery and radio-frequency can also be used in conjunction with resection for patients in whom all metastases are not surgically resectable. The present use of these ablative techniques is improving the percentages of unresectable patients considered for surgery. All of the above-described methods can be combined to achieve a surgical strategy that is as curative as possible, increasing the number of patients primarily unresectable, with a long-term survival hope similar to that of primarily resectable patients. To achieve this objective, a close collaboration between oncologists, radiologists, and surgeons is mandatory, with routine re-evaluation of patients for an adequate timing of each treatment.  相似文献   
104.
105.
OBJECTIVE: Plasmodium falciparum malaria in humans and animal models of this disease have revealed changes in the infected host that are consistent with a systemic inflammatory response. Although it has been proposed that endothelial cell adhesion molecules (CAM) contribute to the adhesive interactions of Plasmodium-infected erythrocytes and immune cells with vascular endothelial cells, ECAM expression has not been systematically studied in Plasmodium-infected animals. METHODS: In this study, the dual radiolabeled monoclonal antibody method was used to quantify the expression of different ECAMs (ICAM-1, VCAM-1, P-selectin, E-selectin) in different regional vascular beds of Plasmodium berghei ANKA-inffected mice (PbA), a well-recognized model of human cerebral malaria. The roles of T lymphocytes and certain cytokines (TNF-alpha, IL-12, IFN-gamma) in mediating the infection-induced expression of ICAM-1 and P-selectin were assessed by using relevant mutant mice. RESULTS: Wild-type (WT) mice exhibited highly significant increases in the expression of ICAM-1, VCAM-1, and P-selectin (but not E-selectin) in all vascular beds on the 6th day of PbA infection. The PbA-induced upregulation of ICAM-1 was significantly blunted in mice that were either deficient in IFN-alpha, IL-12 (but not TNF1b) or T lymphocytes (Rag-1 deficiency); however, these responses were tissue specific. CONCLUSIONS: These findings indicate that vascular endothelial cells in most regional circulations assume an inflammatory phenotype and that cytokines and immune cells mediate this response in a tissue-specific manner.  相似文献   
106.
ObjectivePrevious studies reported associations between insulin-like growth factor I (IGF-I) serum concentration and cardiac morbidity and mortality, but the association between IGF-I serum concentration and cardiac repolarization has not been investigated in a population-based study so far. Therefore, we analyzed the impact of IGF-I concentrations on QTc, QT and RR intervals in two population based studies, The Study of Health in Pomerania (SHIP) and the Rotterdam Study.Design457 individuals from SHIP and 155 individuals from the Rotterdam Study older than 55 years and without cardiovascular diseases and a left ventricular hypertrophy were investigated. IGF-I was determined by automated two-site chemiluminescence immunoassays and electrocardiograms were recorded by an ACTA electrocardiograph at a sampling frequency of 500 Hz. The association of IGF-I with QTc, QT and RR intervals was investigated by multivariable linear regression analyses adjusted for age, gender, diabetes mellitus, myocardial infarction, hypertension, body mass index, serum potassium and calcium in both studies separately and in pooled analysis.ResultsThere were no significant associations between log-transformed IGF-I and QTc interval in the single populations, whereas a significant inverse association was detectable in the pooled population (β, ? 15.6; 95%-confidence interval, ? 25.7, ? 5.5). The QTc interval was significantly higher in the first tertile of IGF-I compared to the third tertile (β, 5.4; 95%-confidence interval, 9.5–1.3) in the pooled analysis.ConclusionThe inverse association between IGF-I serum concentrations and QTc interval in our study is suggestive of a higher risk for cardiac arrhythmias and thus might provide additional evidence for increased cardiovascular mortality in subjects with low IGF-I secretion.  相似文献   
107.
Resistance to ampicillin without β-lactamase production is not a frequent occurrence among Haemophilus influenzae strains. This kind of resistance is encountered in unencapsulated strains isolated from bronchial secretions and ear, nose, and throat specimens and is exceptional in H. influenzae type b. We studied 29 of these strains from various areas in France and 2 reference strains. Strains were compared by using ribotyping, arbitarily primed PCR with two primers, and pulsed-field gel electrophoresis. Each technique enabled the identification of 20 to 23 different patterns among the 31 strains. The combination of the different patterns for the strains obtained by the different techniques provided 27 distinct profiles. According to these results, it seems that the clonal propagation of these resistant strains does not occur.  相似文献   
108.
109.
Fifty-three families with at least one IDD patient were genotyped for 5 markers of the HLA complex including Bf and DR. In 8 families one of the parents was also affected and in 12 families more than two children were diseased. In total, 76 patients were genotyped. Their haplotypes were compared with those of 106 unrelated controls (the parents of 53 genotyped families).
  • 1) 

    Three haplotypes or segments of them (A2, Cw3, B15, BfS, DR4; Aw30, Cw5, B18, BfF I, DR3; and Al, Cw7, B8, BfS, DR3) were found more frequently in IDD patients.

  • 2) 

    Measured by the 6 formula, the association of the postulated IDD susceptibility gene was very strong with the D-end of two of these haplotypes: BfF1, DR3 and BfS, DR4. However, the association was weak with the DR3 of the haplotype Al, Cw7, B8, BfS, DR3.

  • 3) 

    An excess of HLA-identical affected siblings was found.

  • 4) 

    An excess of DR3/DR4 heterozygotes was observed. By contrast, the observed frequency of patients homozygous for DR3 or DR4 was not increased, but even slightly decreased.


The data support a model of inheritance comprising at least two closely linked specifically "diabetic" loci (most of the time marked by B18, BfFl, DR3 and B15, BfS, DR4) and a non-specifically "diabetic" haplotype favouring auto-immunisation (most of the time marked by B8, BfS, DR3). This model is discussed in the light of the presented data and of those of the literature.  相似文献   
110.
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