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   9110篇
  免费   400篇
  国内免费   40篇
耳鼻咽喉   107篇
儿科学   222篇
妇产科学   88篇
基础医学   1125篇
口腔科学   305篇
临床医学   544篇
内科学   2216篇
皮肤病学   147篇
神经病学   663篇
特种医学   459篇
外科学   1697篇
综合类   32篇
预防医学   165篇
眼科学   133篇
药学   479篇
中国医学   17篇
肿瘤学   1151篇
  2023年   39篇
  2022年   78篇
  2021年   122篇
  2020年   62篇
  2019年   108篇
  2018年   162篇
  2017年   157篇
  2016年   183篇
  2015年   170篇
  2014年   254篇
  2013年   309篇
  2012年   504篇
  2011年   590篇
  2010年   339篇
  2009年   356篇
  2008年   548篇
  2007年   598篇
  2006年   612篇
  2005年   603篇
  2004年   634篇
  2003年   594篇
  2002年   575篇
  2001年   79篇
  2000年   86篇
  1999年   133篇
  1998年   167篇
  1997年   154篇
  1996年   151篇
  1995年   113篇
  1994年   119篇
  1993年   121篇
  1992年   62篇
  1991年   65篇
  1990年   59篇
  1989年   54篇
  1988年   46篇
  1987年   41篇
  1986年   46篇
  1985年   36篇
  1984年   47篇
  1983年   46篇
  1982年   43篇
  1981年   42篇
  1980年   32篇
  1979年   19篇
  1978年   29篇
  1977年   17篇
  1976年   16篇
  1974年   17篇
  1973年   15篇
排序方式: 共有9550条查询结果,搜索用时 15 毫秒
31.
32.
A case with lymphadenopathy of the left side of the neck in a 38-year-old male is described. He had a history of several relapses of about 10 years duration. Swollen lymph nodes were histologically similar to those of the hyaline-vascular type of Castleman's disease, but contained clear-cut lymph sinus and a sheet-like proliferation of plasma cells. Lymph follicles showed proliferation and atrophic germinal centers, in which cellular hypertrophy in the wall of ramifying small blood vessels, called angiosclerosis, was frequently encountered. During its progress, the patient developed plasmacytoma of the lymph nodes with varied clinical manifestations such as polyneuropathy, disturbance of gait, unusual perspiration, hirsuitism, gynecomastia, bilateral papilledema, and albumino-cytologic dissociation in cerebrospinal fluid.  相似文献   
33.
The case to be reported is that of a 72-year-old woman with isolated adrenocorticotropic hormone (ACTH) deficiency, who complained of anorexia and generalized malaise. The secretions of human growth hormone(HGH), prolactin (PRL), luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) were all within normal limit. In spite of the extremely low level of Cortisol, the plasma level of AGTH would not rise sufficiently, but a marked response of Cortisol to AGTH stimulation was recognizaed. The postmortem examination revealed a decrease In basophilic or PAS-positive cells of the anterior pituitary gland which also showed a selective loss of AGTH-secreting cells over immunohistochemical study. Electron microscope could easily visualize somatotroph, mammotroph, thyrotroph, FSH- and LH-gonadtroph, but corticotroph was difficult to be discerned. Adrenocortical cells demonstrated atrophy and degeneration, for which the zona fasciculata and zona reticularis were narrowed. The zona glomerulosa was slightly enlarged In width.  相似文献   
34.
Lupus nephritis in a sister and brother pair was histologically analyzed. The 12-year-old sister showed clinically progressive renal failure and her renal pathology disclosed segmental necrotizing and disorganizing glomeru-lonephritis. On the contrary, the 14-year-old brother exhibited nephrotic syndrome and his renal biopsy showed diffuse exudative and proliferative glomerulonephritis with segmental membraneous changes. Although the familial incidence of SLE suggests both genetic and environmental factors existing in the background of SLE of identical twins and siblings, the differences of clinical manifestation and histopathological findings imply that there might be little direct genetic and environmental control on determining the expression of the disease. ACTA PATH. JAP. 29: 607–613, 1979.  相似文献   
35.
36.
Isolated rat Kupffer cells produced a factor which stimulated the synthesis of 2-macroglobulin (2M) in primary cultured rat hepatocytes. Although Kupffer cells placed in culture produced the factor without stimulation by lipopolysaccharide (LPS), the LPS-stimulated cells produced larger amounts of the factor. On the other hand, the production of the factor was inhibited by addition of actinomycin D. The induction of2M synthesis by cultured hepatocytes was enhanced in the presence of dexamethasone (Dex), in that hepatic synthesis of2M increased by addition of the factor alone and with Dex 1.5 and three- to four-fold, respectively. The factor was nondialyzable and stable at 60°C for 30 min. When the factor was fractionated using the molecular sieve method, the activity recovered in the fraction had a molecular weight of over 30,000.  相似文献   
37.
Photocrosslinkable polymers containing chalconecarbonyl units were prepared. 2-Methacryloyloxyethyl 4-chalconecarboxylate ( 1 ) and 2-methacryloyloxyethyl 4′chalconecarboxylate ( 2 ) were synthesized and polymerized by a radical initiator. 1 was copolymerized with methyl methacrylate. The properties of the resulting polymers as photosensitive resins are described.  相似文献   
38.
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   
39.
Cell swelling enhances a slowly activating delayed rectifier K(+) current (I(Ks)) in cardiac cells. This investigation was undertaken to determine which of the two structural units reconstituting the I(Ks) channel, KCNQ1 (KvLQT1) and KCNE1 (minK/IsK), plays a key role in the cell swelling-induced I(Ks) enhancement and to dissect a possible involvement of tyrosine phosphorylation therein. KCNQ1 was transiently expressed alone or together with KCNE1 in a heterologous mammalian cell line. Two distinct whole-cell membrane currents were separately observed during the exposure of transfected cells to various degrees of hyposmotic solutions. A hyposmotic challenge (0.7 times control osmolarity) resulted in about a twofold increase not only in the heteromeric KCNQ1/KCNE1, but also in the homomeric KCNQ1 channel currents. There was no significant difference in the incremental ratio of current amplitude in response to hyposmotic stress between the two KCNQ1-related currents, and the cells expressing the heteromeric channels swelled less than those with the homomeric channels or without the exogenous ones. The cell swelling-induced I(Ks) enhancement was not affected by a protein tyrosine kinase (PTK) inhibitor, by genistein (50 microM), or by an inhibitor of phosphotyrosine phosphatase (PTP), orthovanadate (500 microM), or a nonhydrolyzable ATP analogue, AMP-PNP (5 mM). Taken together, it is very likely that KCNQ1 might primarily participate in the I(Ks) enhancement by osmotic cell swelling. The obligatory dependence of the I(Ks) augmentation on PTK activity remained to be demonstrated, at least, in this expression system.  相似文献   
40.
This study was designed to evaluate the histological changes during ossification and cellular events including osteogenic differentiation responding to collagenous bioresorbable membranes utilized for GBR. Standardized artificial bony defects were prepared at rat maxillae, and covered with a collagenous bioresorbable membrane. These animals were sacrificed at 1, 2, 3 and 4 weeks after the GBR-operation. The paraffin sections were subject to tartrate resistant acid phosphatase (TRAP) enzyme histochemistry and immunohistochemistry for alkaline phosphatase (ALP), osteopontin (OP) and osteocalcin (OC). In the first week of the experimental group, woven bone with ALP-positive osteoblasts occupied the lower half of the cavity. The collagenous membrane included numerous ALP-negative cells and OP-immunoreactive extracellular matrices. At 2 weeks, the ALP-, OP- and OC-immunoreactivity came to be recognizable in the region of collagenous membrane. Since ALP-negative soft tissue separated the collagenous membrane and the new bone originating from the cavity bottom, the collagenous membrane appeared to induce osteogenesis in situ. At 3 weeks, numerous collagen fibers of the membrane were embedded in the adjacent bone matrix. At 4 weeks, the membrane-associated and the cavity-derived bones had completely integrated, showing the same height of the periosteal ridge as the surrounding alveolar bones. The collagen fibers of a GBR-membrane appear to participate in osteogenic differentiation.  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