全文获取类型
收费全文 | 11653篇 |
免费 | 613篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 98篇 |
儿科学 | 218篇 |
妇产科学 | 286篇 |
基础医学 | 1626篇 |
口腔科学 | 239篇 |
临床医学 | 809篇 |
内科学 | 2780篇 |
皮肤病学 | 308篇 |
神经病学 | 996篇 |
特种医学 | 484篇 |
外科学 | 1521篇 |
综合类 | 51篇 |
一般理论 | 1篇 |
预防医学 | 479篇 |
眼科学 | 219篇 |
药学 | 931篇 |
中国医学 | 39篇 |
肿瘤学 | 1232篇 |
出版年
2023年 | 80篇 |
2022年 | 156篇 |
2021年 | 258篇 |
2020年 | 128篇 |
2019年 | 235篇 |
2018年 | 226篇 |
2017年 | 194篇 |
2016年 | 220篇 |
2015年 | 236篇 |
2014年 | 316篇 |
2013年 | 400篇 |
2012年 | 698篇 |
2011年 | 722篇 |
2010年 | 402篇 |
2009年 | 340篇 |
2008年 | 612篇 |
2007年 | 729篇 |
2006年 | 710篇 |
2005年 | 703篇 |
2004年 | 628篇 |
2003年 | 587篇 |
2002年 | 648篇 |
2001年 | 267篇 |
2000年 | 280篇 |
1999年 | 268篇 |
1998年 | 179篇 |
1997年 | 123篇 |
1996年 | 113篇 |
1995年 | 79篇 |
1994年 | 84篇 |
1993年 | 59篇 |
1992年 | 156篇 |
1991年 | 160篇 |
1990年 | 150篇 |
1989年 | 135篇 |
1988年 | 128篇 |
1987年 | 110篇 |
1986年 | 104篇 |
1985年 | 103篇 |
1984年 | 58篇 |
1983年 | 50篇 |
1981年 | 32篇 |
1979年 | 63篇 |
1975年 | 30篇 |
1974年 | 28篇 |
1973年 | 27篇 |
1972年 | 35篇 |
1971年 | 26篇 |
1969年 | 34篇 |
1968年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Bradykinin Stimulates Type II Alveolar Cells to Release Neutrophil and Monocyte Chemotactic Activity and Inflammatory Cytokines 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sekiya Koyama Etsuro Sato Hiroshi Nomura Keishi Kubo Masakazu Miura Tetsuji Yamashita Sonoko Nagai Takateru Izumi 《The American journal of pathology》1998,153(6):1885-1893
In the present study, we evaluated the potential of bradykinin (BK) to induce the release of neutrophil and monocyte chemotactic activity (NCA and MCA) and cytokines from an alveolar type II epithelial cell line, A549 cells. BK stimulated A549 cells to release NCA and MCA in a dose- and time-dependent manner (P < 0.001). Checkerboard analysis revealed that both NCA and MCA involved chemotactic and chemokinetic activity. Molecular sieve column chromatography showed three molecular weight masses (near 19 kd, 8 kd, and 400 d) for NCA and several molecular weight peaks (near 66 kd, 25 kd, 19 kd, 16 kd, and 400 d) for MCA. The release of NCA and MCA was inhibited by cycloheximide and lipoxygenase inhibitors (P < 0.01). The NCA and MCA were inhibited by leukotriene B4 (LTB4) receptor antagonist (P < 0.01), and the concentration of LTB4 was high enough for NCA and MCA. Antibodies to interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF) attenuated NCA (P < 0.01), and antibodies to monocyte chemotactic protein-1 (MCP-1), G-CSF, and transforming growth factor (TGF)-β attenuated MCA (P < 0.01). The levels of IL-8, G-CSF, MCP-1, and TGF-β increased time dependently (P < 0.01). BK also stimulated the release of ILeukin-6 from A549 cells (P < 0.001). The receptors responsible for the release of NCA, MCA, and individual chemokines involved both BKB1 and BKB2 receptors. These data suggest that BK may stimulate alveolar type II pneumocytes to release inflammatory cytokines, which then may modulate the lung inflammation. 相似文献
82.
Koyama C Matsumoto H Sakai T Wakabayashi K Ito A Couch EF Inoue K 《Endocrine pathology》1995,6(1):67-75
A new cell line (TtT/GF) established from a murine pituitary thyrotropic tumor having characteristics similar to those of
pituitary folliculo-stellate cell (FS cell) was implanted into nude mice together with cells from a rat pituitary somatotrophic
tumor cell line (MtT/S) to determine whether the former enhances pituitary tumor growth. For as long as 2-3 mo after implantation,
MtT/S cells implanted either alone or together with fibroblasts formed either no tumors or only very small tumors in the nude
mice. In contrast all of the nude mice that had received MtT/S cells implanted together with TtT/GF cells developed large
tumors. Furthermore, the mice bearing the MtT/S and TtT/GF implants showed a significantly higher body weight and serum growth
hormone level than those bearing only MtT/S cells or a combination of MtT/S cells and fibroblasts. The TtT/GF cell line itself
had no tumorigenicity during the experimental period. Therefore, the TtT/GF cell line as a model of FS cells enhanced pituitary
endocrine cell tumor formation. Additionally, immunocytochemistry showed that TtT/GF cells positive for glial fibrillary acidic
protein (GFAP) or S-100 protein were present in the parenchymatous tissue elements or connective tissue surrounding the tumor
nests. In the parenchymatous tissue, the TtT/GF cells exhibited a stellate appearance and surrounded neighboring tumor cells
with their long cell processes. These results suggest that TtT/GF cells can serve as a model for pituitary FS cells, and are
capable of stimulating pituitary tumor growth either by modifying the microenvironment or producing growth factors. 相似文献
83.
Gondo S Yanase T Okabe T Tanaka T Morinaga H Nomura M Goto K Nawata H 《Genes to cells : devoted to molecular & cellular mechanisms》2004,9(12):1239-1247
Bone marrow stem cells develop into haematopoietic and mesenchymal lineages, but have not been known to participate in steroidogenic cell production. Steroidogenic factor 1 (SF-1), also designated adrenal 4 binding protein (Ad4BP), is an essential orphan nuclear receptor for steroidogenesis as well as for adrenal and gonadal gland development. In the present study, we revealed that the adenovirus-mediated forced expression of SF-1 can transform cultured primary long-term cultured bone marrow cells into steroidogenic cells, showing the de novo synthesis of multiple steroid hormones in response to adrenocorticotropic hormone (ACTH). This finding may provide an initial step in innovative autograft cell transfer therapy for steroid hormone deficiencies. 相似文献
84.
Lon,a stress-induced ATP-dependent protease,is critically important for systemic Salmonella enterica serovar typhimurium infection of mice
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Takaya A Suzuki M Matsui H Tomoyasu T Sashinami H Nakane A Yamamoto T 《Infection and immunity》2003,71(2):690-696
Studies on the pathogenesis of Salmonella enterica serovar Typhimurium infections in mice have revealed the presence of two prominent virulence characteristics-the invasion of the nonphagocytic cells to penetrate the intestinal epithelium and the proliferation within host phagocytic cells to cause a systemic spread and the colonization of host organs. We have recently demonstrated that the ATP-dependent Lon protease of S. enterica serovar Typhimurium negatively regulates the efficiency of invasion of epithelial cells and the expression of invasion genes (A. Takaya et al., J. Bacteriol. 184:224-232, 2002). This study was performed to reveal the contribution of the Lon protease to the virulence of S. enterica serovar Typhimurium in mice. Determination of 50% lethal doses for the lon disruption mutant and wild-type strain revealed that the mutant was highly attenuated when administered either orally or intraperitoneally to BALB/c mice. The mutant was also found to be able to reach extraintestinal sites but unable to proliferate efficiently within the spleen and cause lethal systemic disease of mice. Macrophage survival assays revealed that the lon disruption mutant could not survive or proliferate within murine macrophages. In addition, the mutant showed extremely increased susceptibility to hydrogen peroxide, which contributes to the bactericidal capacity of phagocytes. The mutant also showed increased sensitivity to acidic conditions. Taken together, the impaired ability of the lon disruption mutant to survive and grow in macrophages could be due to the enhanced susceptibility to the oxygen-dependent killing mechanism associated with respiratory burst and the low phagosomal pH. These results suggest that the Lon protease is essentially involved in the systemic infection of mice with S. enterica serovar Typhimurium, which can be fatal. Of further interest is the finding that the lon disruption mutant persists in the BALB/c mice for long periods without causing an overwhelming systemic infection. 相似文献
85.
There is disagreement among researchers concerning whether glutamatergic N-methyl-D-aspartate (NMDA) receptors play a role in constructing spatial representations. Therefore, the authors reexamined the effects of the NMDA antagonist on a spatial discrimination task using rats in a water pool. The authors confirmed that MK-801 impaired acquisition of the spatial discrimination task (Experiment 1). When rats were pretrained before drug treatment, MK-801 induced learning deficits in the novel environment but not in the familiar environment (Experiment 2). Moreover, in a familiar environment, MK-801 did not impair spatial learning, even when the task was completely novel for the rats (Experiment 3). These results suggest that NMDA receptors play an important role in the construction of spatial representations but not in the use of them. 相似文献
86.
Kawakubo Y Kishimoto H Sato Y Yanagimoto K Tsuruta T Ogawa Y Kameya T 《Virchows Archiv : an international journal of pathology》1999,434(2):109-115
Langerhans cell histiocytosis (LCH) has been thought to be a disorder of immune regulation, and increasingly, evidence showing
that the tissue damage in LCH involves lymphokines and pro-inflammatory cytokines is reported. We detected human cytomegalovirus
(HCMV)-DNA in LCH cells in the foci of LCH lesions by immunohistochemistry, in situ hybridization and PCR. HCMV was detected
in the nuclei and/or cytoplasm of LCH cells in 9 of 27 LCH cases by immunostaining. HCMV was probably an early antigen. In
situ hybridization revealed signals for HCMV-DNA only in the nuclei of LCH cells in 10 of the 27 LCH cases. PCR analysis was
performed in 20 of the LCH cases, and HCMV-DNA was detected in 7 of these. All 7 positive cases were also positive for HCMV
by ISH and IHC. These findings suggested that early phase infection or reactivation of HCMV occurred in the LCH lesions. HCMV
infection may be accompanied by impaired cytokine production. Our study also suggested a relationship between HCMV infection
and expression of TNFα. In tissues affected by LCH, dermatopathic lymphadenopathy or malignant fibrous histiocytoma and in
normal tissues no signals for Epstein-Barr virus-RNA were detected. These findings suggest that in some cases LCH is associated
with HCMV infection.
Received: 24 November 1998 / Accepted: 24 April 1998 相似文献
87.
H. Ochiai N. Hishiyama K. Higa K. Koyama M. Seita H. Fujise 《Comparative clinical pathology》2007,16(1):61-63
The cation transport and regulatory volume decrease (RVD) were investigated in the red blood cells (RBCs) of northern fur
seals (Callorhinus ursinus). Extracellular Ca-dependent Na efflux was increased to threefold by hypotonicity. K–Cl cotransport activity was not detected
by hypotonic medium, but measured only by nitrite or N-ethylmaleimide stimulation. RBCs were restored to their original volume after being swollen in hypoosmotic medium with Ca,
though this recovery was inhibited by the addition of quinidine. Based on these results, Na/Ca exchange transporter played
the major role in the regulatory volume decrease in the RBCs of northern fur seals.
H. Fujise has passed away. 相似文献
88.
Shigehito Yamada Chigako Uwabe Tomoko Nakatsu-Komatsu Yutaka Minekura Masaji Iwakura Tamaki Motoki Kazuhiko Nishimiya Masaaki Iiyama Koh Kakusho Michihiko Minoh Shinobu Mizuta Tetsuya Matsuda Yoshimasa Matsuda Tomoyuki Haishi Katsumi Kose Shingo Fujii Kohei Shiota 《Developmental dynamics》2006,235(2):468-477
Morphogenesis in the developing embryo takes place in three dimensions, and in addition, the dimension of time is another important factor in development. Therefore, the presentation of sequential morphological changes occurring in the embryo (4D visualization) is essential for understanding the complex morphogenetic events and the underlying mechanisms. Until recently, 3D visualization of embryonic structures was possible only by reconstruction from serial histological sections, which was tedious and time-consuming. During the past two decades, 3D imaging techniques have made significant advances thanks to the progress in imaging and computer technologies, computer graphics, and other related techniques. Such novel tools have enabled precise visualization of the 3D topology of embryonic structures and to demonstrate spatiotemporal 4D sequences of organogenesis. Here, we describe a project in which staged human embryos are imaged by the magnetic resonance (MR) microscope, and 3D images of embryos and their organs at each developmental stage were reconstructed based on the MR data, with the aid of computer graphics techniques. On the basis of the 3D models of staged human embryos, we constructed a data set of 3D images of human embryos and made movies to illustrate the sequential process of human morphogenesis. Furthermore, a computer-based self-learning program of human embryology is being developed for educational purposes, using the photographs, histological sections, MR images, and 3D models of staged human embryos. 相似文献
89.
Shigeru Furuhata Toru Kameya Tomoko Tsuruta Heiji Naritaka Mitsuhiro Otani Shigeo Toya 《Endocrine pathology》1992,3(4):201-204
A 51 -year-old woman with mixed growth hormone (GH) cell-prolactin (PRL) cell pituitary adenoma is presented. She had clinical
signs due to hypersecretion of GH and PRL. Resected tissue was studied immunohistochemically and morphologically. The serial
sections revealed that GH and α-subunit were co-localized in most cells, while GH and PRL were localized in different cells. 相似文献
90.
Kawauchi S Liu XP Kawasaki K Hirakawa T Amada S Furuya T Oga A Sasaki K 《The Journal of pathology》2004,204(3):268-276
To clarify the mechanisms underlying cell cycle promotion in malignant germ cell tumours of the ovary (MGCTOs), beta-catenin and components of the pRB pathway, cyclin D1 and p16, were analysed in relation to cell proliferation. Immunohistochemically, p16 protein was not expressed in a number of MGCTOs (9 of 42 tumours: 21.4%) and was associated with p16 gene (INK4A) promoter 5'-CpG islands methylation. Amplification of the cyclin D1 gene (CCND1) was detected in a small number of MGCTOs (5 of 42 tumours: 13.5%). Reduced expression of p16 due to promoter methylation correlated significantly with increased cell proliferation as evidenced by Ki-67 labelling index (p < 0.001) and mitotic index (p < 0.01). In some tumour types, nuclear localization of beta-catenin has been reported to be associated with beta-catenin gene (CTNNB1) mutation, cyclin D1 overexpression, and increased cell proliferation. Nuclear localization of beta-catenin, which was observed in MGCTOs other than dysgerminoma, was not associated with cyclin D1 expression and increased cell proliferation, but appeared to be related to tumour differentiation. Furthermore, CTNNB1 mutations were not detected in any of the MGCTOs examined. Our results suggest that reduced expression of p16 due to INK4A promoter methylation is one of the principal factors that promote cell proliferation in MGCTOs. Thus, p16 may be a novel target for gene therapies to treat MGCTOs. 相似文献