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   23862篇
  免费   1146篇
  国内免费   159篇
耳鼻咽喉   224篇
儿科学   545篇
妇产科学   264篇
基础医学   3222篇
口腔科学   411篇
临床医学   1422篇
内科学   6328篇
皮肤病学   579篇
神经病学   1775篇
特种医学   999篇
外科学   4056篇
综合类   123篇
预防医学   578篇
眼科学   572篇
药学   1457篇
中国医学   38篇
肿瘤学   2574篇
  2023年   140篇
  2022年   291篇
  2021年   490篇
  2020年   276篇
  2019年   354篇
  2018年   505篇
  2017年   388篇
  2016年   473篇
  2015年   499篇
  2014年   729篇
  2013年   817篇
  2012年   1398篇
  2011年   1574篇
  2010年   881篇
  2009年   793篇
  2008年   1392篇
  2007年   1547篇
  2006年   1508篇
  2005年   1649篇
  2004年   1657篇
  2003年   1694篇
  2002年   1568篇
  2001年   294篇
  2000年   243篇
  1999年   333篇
  1998年   405篇
  1997年   324篇
  1996年   312篇
  1995年   270篇
  1994年   245篇
  1993年   219篇
  1992年   174篇
  1991年   152篇
  1990年   135篇
  1989年   124篇
  1988年   126篇
  1987年   108篇
  1986年   113篇
  1985年   101篇
  1984年   109篇
  1983年   81篇
  1982年   80篇
  1981年   77篇
  1980年   70篇
  1979年   59篇
  1978年   51篇
  1977年   48篇
  1976年   40篇
  1975年   33篇
  1974年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The HIV/AIDS surveillance system in Japan, which began collecting data on the number of AIDS patients in 1984 and the number of HIV-infected persons in 1987, has played an important role in monitoring the trend and magnitude of Japan's HIV/AIDS epidemic and its distribution across various population subgroups. However, the system lacks any personal identifiers, making it impossible to eliminate duplication or to track cases for disease progression. It also does not permit the identification of the residence of HIV-infected persons because the residence of only the reporting physician is documented under the New Infectious Diseases Control Law, effective since April 1, 1999. The number of people with HIV/AIDS in Japan continues to grow. Among youth, sexually transmitted diseases, induced abortion, and sexual activities have shown a marked increase since the mid-1990s. Behavioral risk of infection for both injection drug users (IDUs) and men who have sex with men (MSM) remains alarmingly high. Accurate monitoring of infection rates is critical to the planning and evaluation of treatment, care and prevention programs. Japan should restructure its HIV/AIDS surveillance system to more accurately monitor the HIV/AIDS epidemic and related risk behaviors.  相似文献   
72.
73.
Non-synaptic, exocytotic release of neurosecretory granules in cerebral ganglion neurons was observed electron microscopically in 3 species of the oligochaete annelids Aporrectodea caliginosa, Octolasion cyaneum and Lumbricus terrestris. In addition to the features indicating exocytotic release of neurosecretory granules into perineuronal space, possible features of neurosecretion into blood vessels were seen within the cerebral ganglion. Axon terminals in synaptic contact with perikaryal profiles of cerebral ganglion neurons were also found.  相似文献   
74.
Summary The pathogenesis of the nodular lesion in diabetic glomerulosclerosis is described in association with fibrils. Thirteen diabetic patients with glomerular nodular lesions and 9 diabetics without the nodules were examined by electron microscopy using periodic acid-thio-carbohydrazide-silver proteinate staining. In cases of nodular glomerulosclerosis, abundant fibrillar structures mixed with electron-dense material were detected within the nodule and the mesangial matrix. They were also occasionally observed along the subendothelial space of the glomerular capillary walls. On the cross-section, these fibrils, including the lucent periphery, were 34 nm wide. Immunohistologically, collagen V and collagen VI were detected in nodular lesions. In contrast, in cases of the diffuse type of glomerulosclerosis, the widened mesangium was composed of dense material, which resembled the original mesangial matrix. The above fibrils were not detected in the mesangium. These findings suggest that the accumulation of the peculiar fibrils in the glomerular mesangium is a major pathogenic factor in the formation of Kimmelstiel-Wilson nodules.  相似文献   
75.
The 6-amino-6-deoxy-N-acetylmuramyldipeptides and their 6-acylamino derivatives were shown to be active as adjuvants on the induction of delayed-type hypersensitivity to azobenzenearsonate-N-acetyl-l-tyrosine in guinea pigs. However, 6-acylamino-6-deoxy-N-(acyl)muramyldipeptides were inactive as adjuvants.  相似文献   
76.
An energy dispersive X-ray microanalysis of the individual corpuscles in the parenchyma ofDiplogonoporus grandis was performed for the chemical identification of their inorganic composition. Besides the corpuscles showing distinct peaks for calcium, a major inorganic element, a type of corpuscle showing distinct peaks for iron was observed. It is suggested that it is necessary to examine not only the whole corpuscles isolated but also individual corpuscles in the tissue when studying the nature and roles of corpuscles in cestodes.  相似文献   
77.
OBJECTIVE: Polo-like kinase 1 (PLK1) is one of the serine-threonine kinases that contributes to cell mitosis and is regarded as a marker of cellular proliferation. However, its protein expression in human carcinoma has not been studied in depth. In this study, we investigated PLK1 expression in medullary thyroid carcinoma by means of immunohistochemistry. METHODS: We immunohistochemically investigated PLK1 expression in 67 cases of medullary thyroid carcinoma. RESULTS: The PLK1 expression level was elevated in 43 of the 67 cases (64.1%). Furthermore, the expression level was directly linked to lymph node metastasis, advanced stage and male sex. All patients who were negative for PLK1 expression are currently alive without tumor recurrence, while 6 of the 43 PLK1-positive patients showed recurrence and 3 have already died of this disease. CONCLUSIONS: These findings suggest that PLK1 expression significantly reflects aggressive characteristics of medullary thyroid carcinoma.  相似文献   
78.
[3H]2-Deoxy-d-glucose (2-DG) was used to investigate the glucose uptake in cultured rat Schwann cells from postnatal Sprague-Dawley rat sciatic nerves. The glucose uptake of Schwann cells slightly increased in a time- and dose-dependent manner. However, the maximal uptake level was much lower than that of ethylnitrosourea (ENU)-induced transformed rat schwannoma-like cells and fibroblasts. By autoradiography of the cultured system, we were able to visualize the accumulation of [3H]2-DG grains in the schwannoma-like cells and fibroblasts, but not in Schwann cells.  相似文献   
79.
80.
Dendritic cell-like cells (Mo-DCs) generated from peripheral blood monocytes with interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been used as tools to treat cancer patients (DC-vaccines). Because Mo-DCs have multiple antigen presentation-related functions, including phagocytosis, migration, cytokine production, and T cell stimulation, establishment of a method for simultaneously evaluating the various functions of Mo-DCs is important. We developed a new in vitro three-dimensional two-layer collagen matrix culture model that consists of a collagen gel containing Mo-DCs as the lower layer and a collagen gel containing necrotic GCTM-1 tumor cells and/or T cells as the upper layer. We used this system to observe simultaneously multiple functions of Mo-DCs by phase-contrast or fluorescence microscopy and to assess IL-12 secretion during more than 2 weeks of culture. We also observed interactions between Mo-DCs and necrotic GCTM-1 or T cells on an individual cell basis by time-lapse videomicroscopy. In addition, we collected Mo-DCs from the collagen gels by collagenase treatment and analyzed the expression of antigen presentation-related molecules such as HLA-DR, CD80, CD83, and CD86 on Mo-DCs. This model may be a useful tool for evaluation of the various functions of Mo-DCs used as DC vaccines and for studies of the complex behaviors of Mo-DCs in vivo.  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