全文获取类型
收费全文 | 2479篇 |
免费 | 104篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 73篇 |
儿科学 | 57篇 |
妇产科学 | 26篇 |
基础医学 | 374篇 |
口腔科学 | 47篇 |
临床医学 | 156篇 |
内科学 | 587篇 |
皮肤病学 | 7篇 |
神经病学 | 296篇 |
特种医学 | 148篇 |
外科学 | 317篇 |
综合类 | 5篇 |
一般理论 | 1篇 |
预防医学 | 114篇 |
眼科学 | 5篇 |
药学 | 172篇 |
中国医学 | 5篇 |
肿瘤学 | 205篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 28篇 |
2020年 | 17篇 |
2019年 | 28篇 |
2018年 | 27篇 |
2017年 | 29篇 |
2016年 | 46篇 |
2015年 | 46篇 |
2014年 | 47篇 |
2013年 | 80篇 |
2012年 | 135篇 |
2011年 | 147篇 |
2010年 | 89篇 |
2009年 | 84篇 |
2008年 | 139篇 |
2007年 | 150篇 |
2006年 | 150篇 |
2005年 | 165篇 |
2004年 | 157篇 |
2003年 | 176篇 |
2002年 | 186篇 |
2001年 | 39篇 |
2000年 | 17篇 |
1999年 | 34篇 |
1998年 | 54篇 |
1997年 | 51篇 |
1996年 | 43篇 |
1995年 | 27篇 |
1994年 | 32篇 |
1993年 | 33篇 |
1992年 | 30篇 |
1991年 | 23篇 |
1990年 | 24篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1974年 | 5篇 |
1970年 | 5篇 |
1957年 | 6篇 |
排序方式: 共有2595条查询结果,搜索用时 15 毫秒
21.
22.
Hiroshi Takahashi Nobuo Tsuda Shuichi Fujita Fumiaki Tezuka Haruo Okabe 《Pathology international》1990,40(9):655-664
Fifty-four adenoid cystic carcinomas (ACC) arising in major and minor salivary glands as well as in normal salivary glands were studied by immunohistochemistry for the presence of vimentin, neuron specific enolase (NSE), α1 -antichymotrypsin (α1 -ACT) and α1 -- antitrypsin (α1 -- AT). Five patterns of histological differentiation were found in ACC, and for the cellular components of each, it was possible to establish a special immunohistochemical profile. In ACC, vimentin-positive cells were observed in the outer tubular, cyst-lining and small angular cells. NSE was positive in the myoepithelial cells of normal salivary gland. Neoplastic cells of ACC showed NSE positivity mainly in the small angular cells and partly in the duct luminal cells. α1 -ACT was localized in the intercalated duct cells and serous acinar cells of normal salivary gland, and in the duct luminal cells of ACC. α1 -AT could not be detected in any of the epithelial cells of normal salivary gland. In ACC, eosinophilic hyaline material in the cribriform spaces was positive for α1 -AT, but no positivity was demonstrated in tumor cells. The present study showed that there are at least two populations of tumor cells in ACC: duct luminal cells that express α1 -ACT, thus indicating their ductal character, and small angular cells that express vimentin, characteristic of non-luminal cells. Moreover, our results indicate that α1 -AT is a useful marker of basement membrane-like material. 相似文献
23.
Kashimura T Kodama M Hotta Y Hosoya J Yoshida K Ozawa T Watanabe R Okura Y Kato K Hanawa H Kuwano R Aizawa Y 《Virchows Archiv : an international journal of pathology》2004,444(3):283-292
Coxsackievirus B is the most common cause of viral myocarditis and is particularly virulent in neonates and children. Adenovirus is also a leading cause of the disease. The determinant of tropism for both viruses is considered to be the expression of coxsackievirus and adenovirus receptor (CAR) in target organs. However, developmental change and physiological localization of CAR in the heart are unknown. We examined expression levels of CAR in rat hearts by quantitative real-time polymerase chain reaction and Western blot analysis and found that CAR decreased gradually during postnatal development, although CAR was detectable, even in adults. Immunohistochemistry revealed CAR on the whole surface of cardiomyocytes in immature rat hearts. In contrast, CAR was detected predominantly on intercalated disks in the adult heart and was accumulated especially at the contact point between the cultured cardiomyocytes, even though they were prepared from the neonatal rat heart. In conclusion, CAR was expressed abundantly on the whole surface of cardiomyocytes in immature rat hearts. Both the expression level and the localization of CAR are possible determinants of the susceptibility to viral myocarditis of neonates and children. 相似文献
24.
Effects of repeated subculturing and prolonged storage at room temperature of enterohemorrhagic Escherichia coli O157:H7 on pulsed-field gel electrophoresis profiles 下载免费PDF全文
Iguchi A Osawa R Kawano J Shimizu A Terajima J Watanabe H 《Journal of clinical microbiology》2002,40(8):3079-3081
Three clinical strains of enterohemorrhagic Escherichia coli O157:H7 which were subcultured repeatedly or stored at room temperature over a 25-week period showed appreciable variations in their pulsed-field gel electrophoresis fragment patterns. The variations could be explained by a couple of spontaneous genetic events at most and thus did not invalidate the genetic lineage of the strains. 相似文献
25.
Amagai T Mouri T Kirii K Hori T Kaneko M Ohkawa H 《Clinical and experimental pharmacology & physiology. Supplement》2002,(29):S19-S22
1. Biliary atresia (BA), as a common disease in Japan, and cystic fibrosis (CF), as an extremely uncommon disease in Japan, were selected to assess the clinical significance of measurement of energy expenditure (EE). 2. Energy expenditure was significantly higher in children with BA than in normal children. 3. Measurement of EE in BA lead to clues to resolving its mechanism by novel assessment of interleukin-6 and leptin. 4. Energy expenditure in children with CF is also higher, but this has been addressed by nutritional intervention with additional calories. 5. Individualization of EE measurement is necessary in the analysis of pathological mechanisms and nutritional management of patients with both common and uncommon diseases. 相似文献
26.
We have addressed the question of whether antigen binding induces a conformational change in the heavy chain constant (C(H)) domain of antibodies using staphylococcal protein A or streptococcal protein G as probes, since these proteins are known to bind to IgG domains such as C(H)1 and C(H)2-C(H)3 domains. Biosensor assays on interactions between these proteins and mouse IgG specific to (4-hydroxy-3-nitrophenyl)acetyl (NP) or their enzymatic fragments conducted in the presence or absence of the hapten, NP-epsilon-aminocaproic acid (NP-Cap), showed that the binding of IgG to these proteins was inhibited by the binding of NP-Cap. The results of isothermal titration calorimetry also revealed that the association constant for the interaction of protein A with IgG2b decreased by the addition of NP-Cap. These results suggested that antigen binding induced conformational changes in binding sites for protein G or protein A located at C(H)1 and C(H)2-C(H)3 domains, respectively. 相似文献
27.
Ernesto Falcidia Agata Grillo Piero Pavone Nunzio Cutuli Haruo Takabayashi Rosario R. Trifiletti Conrad T. Gilliam 《American journal of medical genetics. Part A》2001,101(3):262-267
The isolation and analysis of nucleated fetal cells (NFCs) from maternal blood may represent a new approach to noninvasive prenatal diagnosis. Although promising, these techniques require highly accurate separation of NFCs from nucleated cells of maternal origin; the two major problems limiting these techniques are the relative rarity of fetal cells in maternal blood and the need to establish their fetal origin. We now report a novel procedure that has allowed accurate separation of NFCs from maternal cells. The technique reported involves direct micromanipulator isolation of histochemically identified hemoglobin F‐positive nucleated cells to obtain fetal nucleated red blood cells (FNRBCs) of high yield and purity. Using this technique, followed by cell‐by‐cell multicolor fluorescence in situ hybridization (FISH) analysis of purified FNRBCs, we were able to detect some of the most common human aneuploidies (including Down syndrome, Klinefelter syndrome, and trisomy 13) in 33 pregnant women referred for amniocentesis. The procedure used, which can be completed in <72 hrs, produced complete concordance with the results of amniocentesis. We also confirm findings of prior studies suggesting that the number of FNRBCs in maternal circulation is remarkably higher in abnormal pregnancies than in normal pregnancies, especially in women carrying a fetus with trisomy 21. © 2001 Wiley‐Liss, Inc. 相似文献
28.
During the immune response to T cell-dependent antigen, somatic hypermutation (SHM) is introduced into immunoglobulin (Ig) genes. The variable region is the target for SHM and it is here that DNA lesions are introduced and mutations are generated. It has been suggested that error-prone DNA polymerase(s) may play an important role in this mutagenesis phase. Recently, DNA polymerase kappa (Polkappa), which belongs to the Y-family of DNA polymerases, was identified. Since a hot spot of SHMs (RGYW motif) is also a hot spot of mutations by human Polkappa, this enzyme was suggested to be an SHM instigator. In order to address the question whether Polkappa is involved in SHM, we immunized Polkappa-deficient mice and analyzed the SHM of the Ig heavy chain gene. We found that the SHM frequency and spectrum were indistinguishable between the Polkappa knockout mice and control mice. These results suggested that Polkappa is not essential for this process. 相似文献
29.
Haruo Hagiwara Nobuo Ohwada Takeo Aoki Takeshi Suzuki Kuniaki Takata 《Medical molecular morphology》2008,41(4):221-226
Stromal cells in the lamina propria of the human oviduct mucosa are unique cells that can differentiate into decidual cells
during ectopic pregnancy in the oviduct. The nature of stromal cells is still unknown. In the present study, we investigated
human oviductal stromal cells with transmission electron microscopy and immunohistochemistry and revealed that they had ultrastructural
features similar to myofibroblasts and expressed alpha-smooth muscle actin, a marker used to identify myofibroblasts. Primary
cilia were also one of the characteristic profiles of the stromal cells. These findings showed that the connective tissue-stromal
cells in the human oviduct mucosa are myofibroblasts. They are considered to play an important role in the transport of oocytes
by bringing about contraction of the mucosal folds. 相似文献
30.
Haruo Ohtani 《Pathology international》1998,48(1):1-9
Cancers are characterized by invasive growth and distant metastasis. Cancer cells not only destroy the pre-existing extracellular matrix, but cancer invasion per se usually induces new matrix formation by activation of stromal cells; that is, desmoplastic reaction. This process includes both matrix production and degradation; that Is, the remodeling process. The similarity between desmoplastic reactions in cancer stroma and the wound healing process has already been pointed out, and it has been well documented that matrix-degrading processes are actively involved In the wound healing process. A recent study revealed that most matrix-degrading enzymes, generally considered to be one of the main mechanisms of cancer invasion and metastasis, are originated from stromal cells. Based on these preconditions, the present review postulates that the abundant expression of matrix-degrading enzymes by fibroblasts, coupled with the abundant expression of type I procollagen, is involved in the matrix remodeling processes occurring in cancer stroma; that is, the mechanism similar to the wound healing process. Next, macrophages distributed along the invasive margin are known to express matrix-degrading enzymes/factors. Data from past studies of colon carcinoma indicate that the tissue expression of matrix metalloproteinase-9 and urokinase-type plas-mlnogen activator receptor Is inversely associated with simultaneous liver metastasis and infiltrating growth pattern. Previous clinicopathologic data have indicated that immune/Inflammatory cells are one of the factors for a favorable prognosis. This suggests that the expression of matrix-degrading enzymes/factors by these host cells may be involved in host immune/inflammatory reactions, and that the net function of these cells can be defensive towards the host. Data from past studies of colon carcinoma on the expression of the intercellular adhesion molecule-1 suggest that the interaction between macrophages, lymphocytes, and the phenotypes of venules distributed along the Invasive margin, further support the pro-inflammatory milieu there. Therefore, the matrix degradation process in cancer tissue is multifunctional: besides the Involvement in cancer invasion and metastasis, the matrix degradation process is also involved in the tissue remodeling process and in the immune/inflammatory reaction occurring in the stroma. 相似文献