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   1025篇
  免费   113篇
  国内免费   8篇
耳鼻咽喉   1篇
儿科学   59篇
妇产科学   12篇
基础医学   125篇
口腔科学   23篇
临床医学   121篇
内科学   214篇
皮肤病学   19篇
神经病学   49篇
特种医学   40篇
外科学   89篇
综合类   19篇
预防医学   121篇
眼科学   13篇
药学   126篇
中国医学   22篇
肿瘤学   93篇
  2024年   2篇
  2023年   15篇
  2022年   56篇
  2021年   71篇
  2020年   37篇
  2019年   42篇
  2018年   46篇
  2017年   26篇
  2016年   41篇
  2015年   55篇
  2014年   36篇
  2013年   48篇
  2012年   52篇
  2011年   63篇
  2010年   51篇
  2009年   45篇
  2008年   62篇
  2007年   64篇
  2006年   41篇
  2005年   41篇
  2004年   45篇
  2003年   38篇
  2002年   30篇
  2001年   18篇
  2000年   4篇
  1999年   10篇
  1998年   13篇
  1997年   9篇
  1996年   15篇
  1995年   14篇
  1994年   14篇
  1993年   9篇
  1992年   3篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   5篇
  1986年   2篇
  1985年   4篇
  1984年   4篇
  1982年   1篇
  1981年   1篇
  1980年   4篇
  1979年   1篇
  1976年   1篇
  1973年   1篇
排序方式: 共有1146条查询结果,搜索用时 15 毫秒
71.
We examined whether the detection of dysgranulopoiesis in blood or bone marrow would predict chronic myeloid leukemia (CML) in transformation in 31 cases that fulfilled World Health Organization criteria for disease transformation, including 14 in accelerated phase (AP), 10 in myeloid blast crisis (MBC), and 7 in lymphoid blast crisis (LBC). Dysgranulopoiesis was detected in 7 cases, 6 in AP and 1 in MBC, but not in LBC or chronic phase cases. In 3 AP cases, dysgranulopoiesis was identified 2 to 5 months before the morphologic diagnosis of transformation. Two AP cases showed no dysgranulopoiesis in previous blood or marrow smears. For 2 cases (1 AP and 1 MBC), no previous blood or marrow specimens were available. Cytogenetic information was available for 6 of 7 cases with and 22 of 24 cases without dysgranulopoiesis. All cases with dysgranulopoiesis had secondary chromosome abnormalities in addition to t(9;22). In 5 (83%) of 6 cases with dysgranulopoiesis, the secondary chromosome abnormalities included abnormalities of 17p. In contrast, none of the 22 cases of CML in AP or BC but without dysgranulopoiesis showed 17p abnormalities (P = .001). Our findings demonstrated that dysgranulopoiesis was associated strongly with chromosome 17p abnormalities and may indicate the onset of or impending disease transformation.  相似文献   
72.
Severino ME  Sarkis PT  Walker BD  Yang OO 《Virology》2003,306(2):371-375
Transduction of T cells with a chimeric immune T cell receptor (CIR) has been proposed as a strategy to generate cellular immunity against viral pathogens such as HIV-1. In the case of the CD4-CD3-zeta chain (CD4-zeta) CIR, specificity for HIV-1 is conferred by binding of the CD4 moiety to gp120 on the surface of infected cells. However, it is unclear whether CD4-zeta-T cells may differ from naturally derived CD8(+) cytotoxic T cells (CTL) in their susceptibility to viral escape mechanisms or ability to recognize different cell types that support viral replication. We demonstrate that CIR-T cells can mediate antiviral activity against HIV-1 in cells that are resistant to class I-restricted CTL-mediated activity. Furthermore, CIR-T cells can suppress virus in multiple cell types, including monocytes, dendritic cells, and lymphocyte-dendritic cell clusters. These results provide evidence that T cells can be redirected against novel targets, and that independence from the class I pathway may have distinct advantages.  相似文献   
73.
BACKGROUND: The health benefits of breast-feeding are widely acknowledged and breast-feeding is crucial for the survival of the infants in developing countries. The present study aims to elucidate the prevalence of breast-feeding and the possible risk factors affecting the breast-feeding of infants at the age of 3 months in Ho Chi Minh City, Vietnam after the World Health Organization and the United Nations Children's Fund launched "the Baby-Friendly Hospital" Initiative in 1989. METHODS: A cross-sectional study was conducted in the urban areas of Ho Chi Minh City, Vietnam in February, 2000. Two hundred and sixty mother-infant pairs were conveniently recruited in three child health centers in Ho Chi Minh City. Mothers of infants aged 6-12 months were interviewed and completed a well-structured questionnaire regarding the feeding types of the infant, the maternal knowledge, attitudes and behaviors related to breast-feeding. RESULTS: The results indicated that although about 86.4% newborns in the maternity wards and 88.5% infants at 3 months were at least partially fed with breast milk, the prevalence of breast-feeding were 57.4 and 53.1%, respectively. About 47.5% newborns were fed with breast milk in the first feeding. The multivariate logistic regression analysis shows that the risk factors for the introduction of breast milk substitutes at 3 months of age were maternal antenatal plan of mixed or artificial feeding (odds ratio (OR) = 6.59, 95% confidence interval (CI): 3.18-13.64, P < 0.001) and the supplement of breast milk substitutes in the maternity ward (OR = 4.30, 95% CI: 2.10-8.77, P < 0.001). Higher maternal education levels were beneficial to the continuation of breast-feeding. About 18.5% mothers had attended antenatal breast-feeding education. Most of the mothers (94.1%) and families (95.4%) indicated supportive attitudes to breast-feeding. CONCLUSION: The prevalence of breast-feeding was relatively low in Ho Chi Minh City, Vietnam. The antenatal education in breast-feeding needs to be improved and the implementation of the "Baby-Friendly Hospital" policy needs to be strengthened.  相似文献   
74.
Extracellular protons inhibit N-methyl-D-aspartate (NMDA) receptors with an IC50 value in the physiological pH range. To identify the molecular determinants of proton sensitivity, we used scanning mutagenesis of the NR1 subunit to search for residues that control proton inhibition of NMDA receptors. Homology modeling of the extracellular domains suggested that residues at which mutations perturbed pH sensitivity were localized in discrete regions. The majority of mutations that strongly affected proton sensitivity were clustered in the extracellular end of the second transmembrane domain (M3) and adjacent linker leading to the S2 portion of the glycine-binding domain of NR1. Mutations in NR2A confirmed that the analogous region controls the pH sensitivity of this subunit and also identified the linker region between the third transmembrane domain (M4) and the S2 portion of the NR2 glutamate binding domain as an additional determinant of proton sensitivity. One mutant receptor, NR1(A649C)/NR2A(A651T), showed a 145-fold reduction in the IC50 for protons (IC50, 17.3 microM corresponding to pH 4.9). The M3-S2 linker region has been suggested to control NMDA receptor gating, leading to the hypothesis that the proton sensor and receptor gate may be structurally and functionally integrated.  相似文献   
75.
76.
This study aimed to develop docetaxel (DTX) loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (DTX-NPs) and to evaluate the different pharmacological sensitivity of NPs to MCF-7 and MDA-MB-231 breast cancer cells. NPs containing DTX or coumarin-6 were prepared by the nanoprecipitation method using PLGA as a polymer and d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) as a surfactant. The physicochemical properties of NPs were characterized. In vitro anticancer effect and cellular uptake were evaluated in breast cancer cells. The particle size and zeta potential of the DTX-NPs were 160.5 ± 3.0 nm and –26.7 ± 0.46 mV, respectively. The encapsulation efficiency and drug loading were 81.3 ± 1.85% and 10.6 ± 0.24%, respectively. The in vitro release of DTX from the DTX-NPs was sustained at pH 7.4 containing 0.5% Tween 80. The viability of MDA-MB-231 and MCF-7 cells with DTX-NPs was 37.5 ± 0.5% and 30.3 ± 1.13%, respectively. The IC50 values of DTX-NPs were 3.92- and 6.75-fold lower than that of DTX for MDA-MB-231 cells and MCF-7 cells, respectively. The cellular uptake of coumarin-6-loaded PLGA-NPs in MCF-7 cells was significantly higher than that in MDA-MB-231 cells. The pharmacological sensitivity in breast cancer cells was higher on MCF-7 cells than on MDA-MB-231 cells. In conclusion, we successfully developed DTX-NPs that showed a great potential for the controlled release of DTX. DTX-NPs are an effective formulation for improving anticancer effect in breast cancer cells.  相似文献   
77.
The malignant nature of hepatocellular carcinoma (HCC) is closely related to the presence of cancer stem cells (CSCs). Bone morphologic protein 9 (BMP9), a member of the transforming growth factor‐beta (TGF‐β) superfamily, was recently reported to be involved in liver diseases including cancer. We aimed to elucidate the role of BMP9 signaling in HCC‐CSC properties and to assess the therapeutic effect of BMP receptor inhibitors in HCC. We have identified that high BMP9 expression in tumor tissues or serum from patients with HCC leads to poorer outcome. BMP9 promoted CSC properties in epithelial cell adhesion molecule (EpCAM)‐positive HCC subtype via enhancing inhibitor of DNA‐binding protein 1 (ID1) expression in vitro. Additionally, ID1 knockdown significantly repressed BMP9‐promoted HCC‐CSC properties by suppressing Wnt/β‐catenin signaling. Interestingly, cells treated with BMP receptor inhibitors K02288 and LDN‐212854 blocked HCC‐CSC activation by inhibiting BMP9‐ID1 signaling, in contrast to cells treated with the TGF‐β receptor inhibitor galunisertib. Treatment with LDN‐212854 suppressed HCC tumor growth by repressing ID1 and EpCAM in vivo. Our study demonstrates the pivotal role of BMP9‐ID1 signaling in promoting HCC‐CSC properties and the therapeutic potential of BMP receptor inhibitors in treating EpCAM‐positive HCC. Therefore, targeting BMP9‐ID1 signaling could offer novel therapeutic options for patients with malignant HCC.  相似文献   
78.
79.
The diagnostic value of biphasic radiographic examination of the stomach and duodenum was compared with that of fiberoptic endoscopy in a prospective, blinded study of 385 patients with dyspepsia. This investigation was directed at gastric malignancies and peptic ulcers. Methodologically there is no absolute standard for a study of this kind because histologic examination is useful for detection of cancer but inadequate for ulcers. As an alternative, kappa indexes and the sensitivity and specificity, as derived by Hui and Walter, were calculated and compared. For the detection of gastric carcinoma, radiographic and endoscopic findings had almost perfect agreement beyond chance. For gastric ulcers, radiography and endoscopy had substantial agreement, which became perfect if small ulcers (less than 5 mm) were excluded. For duodenal ulcers, radiography had a lower sensitivity than endoscopy; this disagreement disappeared if small ulcers were excluded. Both methods have equal merit; choice of the initial diagnostic procedure will therefore depend on cost, discomfort to the patient, and risk of complications.  相似文献   
80.
Vaccination coverage since the selective hepatitis B vaccination of neonates of highrisk group program introduced in 1987, was measured in 658 children from 301 Vietnamese families living in the southwestern Sydney. The vaccination rate of children born after the introduction of the program was twice that of children born before its implementation (OR=2.00, 95% Cl 1.65–2.42). The shorter the mother's duration of residency in Australia, the more likely her children were to be fully vaccinated (OR=2.49, 95% Cl 2.43-2.62). A catch-up vaccination program of older siblings is required to assist the public health strategy to reduce the morbidity and mortality from hepatitis B viral infection.  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