全文获取类型
收费全文 | 4071篇 |
免费 | 228篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 112篇 |
妇产科学 | 27篇 |
基础医学 | 583篇 |
口腔科学 | 87篇 |
临床医学 | 261篇 |
内科学 | 1165篇 |
皮肤病学 | 22篇 |
神经病学 | 252篇 |
特种医学 | 180篇 |
外科学 | 749篇 |
综合类 | 19篇 |
预防医学 | 80篇 |
眼科学 | 23篇 |
药学 | 221篇 |
中国医学 | 6篇 |
肿瘤学 | 554篇 |
出版年
2023年 | 37篇 |
2022年 | 68篇 |
2021年 | 135篇 |
2020年 | 65篇 |
2019年 | 76篇 |
2018年 | 142篇 |
2017年 | 88篇 |
2016年 | 115篇 |
2015年 | 129篇 |
2014年 | 164篇 |
2013年 | 183篇 |
2012年 | 351篇 |
2011年 | 352篇 |
2010年 | 174篇 |
2009年 | 158篇 |
2008年 | 256篇 |
2007年 | 289篇 |
2006年 | 268篇 |
2005年 | 215篇 |
2004年 | 225篇 |
2003年 | 237篇 |
2002年 | 194篇 |
2001年 | 35篇 |
2000年 | 34篇 |
1999年 | 42篇 |
1998年 | 52篇 |
1997年 | 35篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 19篇 |
1993年 | 26篇 |
1992年 | 31篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有4349条查询结果,搜索用时 31 毫秒
21.
Masashi Ichinose Mitsuru Saito Naoto Fujii Narihiko Kondo Takeshi Nishiyasu 《The Journal of physiology》2006,576(3):947-958
We tested the hypothesis that arterial baroreflex (ABR)-mediated beat-to-beat control over muscle sympathetic nerve activity (MSNA) is progressively modulated as orthostatic stress increases in humans, but that this control becomes impaired just before the onset of orthostatic syncope. In 17 healthy subjects, the ABR control over MSNA (burst incidence, burst strength and total MSNA) was evaluated by analysing the relationship between beat-to-beat spontaneous variations in diastolic blood pressure (DAP) and MSNA during supine rest (control) and during progressive, stepwise increases in lower body negative pressure (LBNP) that were incremented by −10 mmHg every 5 min until presyncope (nine subjects) or −60 mmHg was reached. (1) The linear relationships between DAP and burst strength and between DAP and total MSNA were shifted progressively upward as LBNP increased until the level at which syncope occurred. The relationship between DAP and burst incidence, however, gradually shifted upward from control only to LBNP =−30 mmHg; there was no further upward shift at higher LBNPs. (2) Although the slope of the relationship between DAP and burst strength and between DAP and total MSNA remained constant at all LBNPs tested, except at the level where syncope occurred, the slope of the relationship between DAP and burst incidence was reduced at LBNPs of −40 mmHg and higher ( versus control). (3) In syncopal subjects, the slopes of the relationships between DAP and burst incidence, burst strength, and total MSNA were all substantially reduced during the 1–2 min period prior to the onset of syncope. Taken together, these results suggest baroreflex control over MSNA is progressively modulated as orthostatic stress increases, so that its sensitivity is substantially reduced during the period immediately preceding the severe hypotension associated with orthostatic syncope. 相似文献
22.
Saito S Matsui T Kobayashi N Wakisaka H Mominoki K Matsuda S Taniguchi K 《Anatomy and embryology》2003,206(5):349-356
Expression patterns of glycoconjugates were examined by lectin histochemistry in the nasal cavity of the Japanese red-bellied newt, Cynops pyrrhogaster. Its nasal cavity consisted of two components, a flattened chamber, which was the main nasal chamber (MNC), and a lateral diverticulum called the lateral nasal sinus (LNS), which communicated medially with the MNC. The MNC was lined with the olfactory epithelium (OE), while the diverticulum constituting the LNS was lined with the vomeronasal epithelium (VNE). Nasal glands were observed beneath the OE but not beneath the VNE. In addition, a secretory epithelium was revealed on the dorsal boundary between the MNC and the LNS, which we refer to as the boundary secretory epithelium (BSE) in this study. The BSE seemed to play an important role in the construction of the mucous composition of the VNE. Among 21 lectins used in this study, DBA, SBA and Jacalin showed different staining patterns between the OE and the VNE. DBA staining showed remarkable differences between the OE and the VNE; there was intense staining in the free border and the supporting cells of the VNE, whereas there was no staining or weak staining in the cells of the OE. SBA and Jacalin showed different stainings in the receptor neurons for the OE and the VNE. Furthermore, UEA-I and Con A showed different stainings for the nasal glands. UEA-I showed intense staining in the BSE and in the nasal glands located in the ventral wall of the MNC (VNG), whereas Con A showed intense staining in the BSE and in the nasal glands located in the dorsal and medial wall of the MNC (DMNG). The DMNG were observed to send their excretory ducts into the OE, whereas no excretory ducts were observed from the VNG to the OE or the VNE. These results suggested that the secretion by the supporting cells as well as the BSE and the DMNG establishes that there are heterogeneous mucous environments in the OE and the VNE, although both epithelia are situated in the same nasal cavity. 相似文献
23.
24.
Cell biology and pathology of liver sinusoidal endothelial cells 总被引:9,自引:0,他引:9
Katsuhiko Enomoto Yuji Nishikawa Yasufumi Omori Takuo Tokairin Masayuki Yoshida Naoto Ohi Takuya Nishimura Youhei Yamamoto Qinchang Li 《Medical Electron Microscopy》2004,37(4):208-215
Growing evidence revealed that liver sinusoidal endothelial cells (SEC) play several important roles in physiology and pathology of the liver. It has been well understood that their structural characteristics, such as the membrane sieve and lack of basement membrane, facilitate direct contact of soluble and insoluble serum substances with hepatic parenchymal cells, resulting in enhancement of hepatic metabolic activity. In addition, SEC is now regarded as a member of the scavenger endothelial cells, which have potential to eliminate a variety of macromolecules from the blood circulation by receptor-mediated endocytosis. It is reported that molecules preferentially eliminated by SEC are denatured or modified proteins such as advanced glycation end products, extracellular matrix components including hyaluronic acid, and some lipoproteins. The nature of the scavenger receptors corresponding to these molecules remains to be clarified. Recently, it was noted that SEC has an antigen-presenting function similar to dendritic cells. Taken together, it is suggested that SEC, cooperating with Kupffer cells and hepatic dendritic cells, may partake of immunoregulatory functions in the liver. SEC also plays a pivotal role in the pathological process of ischemia-reperfusion injury following liver surgery and liver transplantation. Thus, it is of importance to elucidate the mechanisms of apoptosis and proliferation of SEC. Recent results on the regulation of growth and apoptotic signaling of SEC are discussed. 相似文献
25.
Teiji Tsuruta Shohei Inoue Michio Yoneyama Naoto Yamada 《Macromolecular chemistry and physics.》1967,110(1):133-143
Copolymerization of N-carboxy-γ-benzyl-L -glutamate anhydride and ethylene oxide or DL-propylene oxide was carried out in the presence of triethylaluminum or diethylzine as catalyst with (or without) dioxane as solvent. From the data obtained by nuclear magnetic resonance spectroscopy, optical rotatory dispersion measurements, infrared absorption spectroscopy and turbidimetry, it was concluded that the copolymer obtained by the triethylaluminum catalyst consisted of two parts, peptide-block part and random or alternate part, while diethylzinc catalyst resulted in the formation of a less random copolymer only. In dioxane, formation of peptide-block part by triethylaluminum was suppressed to some extent. 相似文献
26.
Saiki O Uda H Nishimoto N Miwa T Mima T Ogawara T Azuma N Katada Y Sawaki J Tsutsui H Matsui K Maeda A Nakanishi K 《Clinical immunology (Orlando, Fla.)》2004,112(1):120-125
Adult Still's disease (ASD) is a chronic multisystemic disease. Extraordinarily high serum levels of IL-18 in ASD patients have been described, whereas the mechanism remains to be clarified. This study aimed to evaluate proinflammatory cytokines and to consider their pathological roles. In patients with rheumatic diseases (n = 151), blood samples were taken at the active phase and the serum levels of IL-18 and other proinflammatory cytokines were measured by ELISA. The extra-high levels of IL-18 were confirmed selectively in ASD patients (n = 10). In the active phase of ASD patients, the levels of IL-6 were elevated accordingly, but IL-1beta and TNF-alpha were undetectable. As to Th1-Th2 cytokines, the levels of IL-4 and IL-13, but not INF-gamma, IL-12, or IL-2, were elevated in all ASD patients examined. Moreover, the serum levels of IL-18 showed a good correlation with those of IL-4, suggesting that ASD reflects a Th2 rather than a Th1 cytokine profile. 相似文献
27.
Teramoto M Kitawaki J Koshiba H Kitaoka Y Obayashi H Hasegawa G Nakamura N Yoshikawa T Matsushita M Maruya E Saji H Ohta M Honjo H 《American journal of reproductive immunology (New York, N.Y. : 1989)》2004,51(5):352-357
PROBLEM: Tumor necrosis factor (TNF)-alpha is a major cytokine involved in inflammatory and immune function. The aim of this study was to investigate whether polymorphisms at positions -1031, -863 and -857 in the TNF gene promoter region (TNFA) and TNF receptor type 2 gene (TNFR2) are responsible in part for genetic susceptibility to endometriosis. METHODS OF STUDY: TNFA and TNFR2 polymorphisms were determined in 123 patients with endometriosis and 165 fertile healthy women by the polymerase chain reaction (PCR) - preferential homoduplex formation assay and PCR-restriction fragment length polymorphism, respectively. RESULTS: The frequency of the TNFA-U01 haplotype was increased significantly in patients with endometriosis compared with controls (P = 0.045, OR = 1.45). The TNFA-U01 haplotype was strongly associated with HLA-B*0702. No difference was found in TNFR2 polymorphism between patients and controls. CONCLUSION: Our results indicated that TNFA promoter polymorphism was associated with susceptibility to endometriosis. However, this association was not independent of HLA-class I polymorphisms. 相似文献
28.
29.
Expression of the IL-2 receptor {gamma} chain on various populations in human peripheral blood 总被引:8,自引:0,他引:8
Ishii Naoto; Takeshita Toshikazu; Kimura Yutaka; Tada Kohtaro; Kondo Motonari; Nakamura Masataka; Sugamura Kazuo 《International immunology》1994,6(8):1273-1277
We have established two rat mAbs, TUGH4 and TUGh5, specificfor the human chain of the IL-2 receptor (IL-2R), which isknown to be shared among receptors for IL-2, IL-4 and IL-7.The antibodies bound to cell lines transfected with the human chain gene but not to their parental cell lines, and precipitated65–70 and 80–90 kDa cell surface molecules fromlysates of human T cells surface-labeled with Na125I and chemicallycross-linked with [125]IL-2 respectively. Flow cytometry withTUGh4 and TUGh5 detected the chain in a wide variety of peripheralblood cell populations including CD4+ T cells, CD20+ T cells,CD20+ B cells, CD56+ natural killer cells, CD4+ monocytes andgranulocytes, contrasting with expression of the and ßchains of IL-2R. 相似文献
30.
Yongchol Shin Atsushi Kitayama Tetsuya Koide Daniel A Peiffer Makoto Mochii Arnold Liao Naoto Ueno Ken W Y Cho 《Developmental dynamics》2005,232(2):432-444
To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning. 相似文献