全文获取类型
收费全文 | 13801篇 |
免费 | 592篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 223篇 |
儿科学 | 220篇 |
妇产科学 | 178篇 |
基础医学 | 1807篇 |
口腔科学 | 312篇 |
临床医学 | 820篇 |
内科学 | 3811篇 |
皮肤病学 | 289篇 |
神经病学 | 804篇 |
特种医学 | 693篇 |
外科学 | 2206篇 |
综合类 | 56篇 |
预防医学 | 403篇 |
眼科学 | 146篇 |
药学 | 989篇 |
中国医学 | 60篇 |
肿瘤学 | 1428篇 |
出版年
2023年 | 43篇 |
2022年 | 104篇 |
2021年 | 202篇 |
2020年 | 131篇 |
2019年 | 190篇 |
2018年 | 208篇 |
2017年 | 186篇 |
2016年 | 234篇 |
2015年 | 217篇 |
2014年 | 330篇 |
2013年 | 444篇 |
2012年 | 729篇 |
2011年 | 790篇 |
2010年 | 428篇 |
2009年 | 401篇 |
2008年 | 758篇 |
2007年 | 808篇 |
2006年 | 887篇 |
2005年 | 878篇 |
2004年 | 783篇 |
2003年 | 757篇 |
2002年 | 708篇 |
2001年 | 331篇 |
2000年 | 343篇 |
1999年 | 345篇 |
1998年 | 231篇 |
1997年 | 149篇 |
1996年 | 146篇 |
1995年 | 114篇 |
1994年 | 107篇 |
1993年 | 104篇 |
1992年 | 224篇 |
1991年 | 200篇 |
1990年 | 184篇 |
1989年 | 184篇 |
1988年 | 160篇 |
1987年 | 159篇 |
1986年 | 144篇 |
1985年 | 140篇 |
1984年 | 105篇 |
1983年 | 74篇 |
1982年 | 42篇 |
1981年 | 56篇 |
1980年 | 57篇 |
1979年 | 66篇 |
1978年 | 40篇 |
1977年 | 53篇 |
1975年 | 43篇 |
1971年 | 45篇 |
1968年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
82.
Dexamethasone inhibits induction of liver tumor necrosis factor-alpha mRNA and liver growth induced by lead nitrate and ethylene dibromide. 下载免费PDF全文
G. M. Ledda-Columbano A. Columbano A. Cannas G. Simbula K. Okita K. Kayano Y. Kubo S. L. Katyal H. Shinozuka 《The American journal of pathology》1994,145(4):951-958
We have recently demonstrated that a single injection of the mitogen lead nitrate to rats induced a rapid increase of tumor necrosis factor-alpha (TNF-alpha) mRNA in the liver and suggested that this cytokine may be involved in triggering hepatocyte proliferation in this model of direct hyperplasia. In this study, we examined whether a similar induction of liver TNF-alpha mRNA could be observed preceding the onset of hepatocyte proliferation induced by ethylene dibromide, another hepatocyte mitogen. In addition, we used dexamethasone, a well known inhibitor of TNF-alpha production, to determine whether its administration could suppress hepatocyte proliferation induced by lead nitrate and ethylene dibromide. A single intragastric administration of ethylene dibromide (100 mg/kg) to male Wistar rats enhanced liver TNF-alpha mRNA after 4 and 7 hours, which then returned to control levels by 24 hours. TNF-alpha mRNA was detectable only in a nonparenchymal cell fraction of the liver. Pretreatment of rats with a single dose of dexamethasone (2 mg/kg) 60 minutes before lead nitrate (100 mumol/kg) or ethylene dibromide completely abolished the increased levels of liver TNF-alpha mRNA induced by these agents. Inhibition by dexamethasone of TNF-alpha mRNA was associated with an inhibition of liver cell proliferation induced by these mitogens, as measured by [3H]thymidine incorporation into hepatic DNA, mitotic index, and DNA content. These results further support the hypothesis that TNF-alpha may be involved in triggering hepatocyte proliferation induced by primary mitogens. 相似文献
83.
84.
85.
Increased expression levels of integrin alphavbeta5 on scleroderma fibroblasts 总被引:1,自引:0,他引:1 下载免费PDF全文
Integrin alphavbeta5 is a receptor for vitronectin, a plasma glycoprotein that is also distributed in extracellular matrix of various tissues. Matrix-bound vitronectin has the potential to stabilize the active form of plasminogen activator inhibitor-1, resulting in the inhibition of the plasmin-mediated pericellular proteolytic cascade. In this study, we compared the levels of alphavbeta5 and matrix-bound vitronectin between normal and scleroderma fibroblasts and investigated the association with fibrosis. We demonstrated that alphavbeta5 was up-regulated on scleroderma fibroblasts. The up-regulated alphavbeta5 contributed to the increase in vitronectin-binding ability in scleroderma fibroblasts, which led to the vitronectin-dependent activation of plasminogen activator inhibitor-1. In immunohistochemistry, the alphav and beta5 subunits were stained strongly on scleroderma fibroblasts and the amount of vitronectin was increased in the pericellular matrix of those cells. The transient overexpression of alphavbeta5 on normal fibroblasts enhanced the human alpha2(I) collagen promoter activity through Sp-1 and Smad3 as well as the vitronectin-dependent plasminogen activator inhibitor-1 activity. This effect on the promoter activity was also observed in the absence of vitronectin and completely disappeared in the presence of anti-alphavbeta5 antibody. These results indicate that the up-regulated alphavbeta5 may contribute to the phenotypical alteration of scleroderma fibroblasts, while at the same time suppressing the plasmin-mediated pericellular proteolytic cascade. 相似文献
86.
Yoshiharu Yamamoto Mitsumasa Miyashita Richard L. Hughson Shin-ichi Tamura Minoru Shinohara Yoshiteru Mutoh 《European journal of applied physiology》1991,63(1):55-59
Summary The purpose of this study was to examine whether the ventilatory threshold (Th
v) would give the maximal lactate steady state ([1a]ss, max), which was defined as the highest work rate (W) attained by a subject without a progressive increase in blood lactate concentration [1a]b at constant intensity exercise. Firstly, 8 healthy men repeated ramp-work tests (20 W·min–1) on an electrically braked cycle ergometer on different days. During the tests, alveolar gas exchange was measured breath-by-breath, and theW atTh
v (W
Th
v) was determined. The results of two-way ANOVA showed that the coefficient of variation of a singleW
Th
v determination was 2.6%. Secondly, 13 men performed 30-min exercise atW
Th
v (Th
v trial) and at 4.9% aboveW
Th
v (Th
v + trial), which corresponded to the 95% confidence interval of the single determination. The [1a]b was measured at 15 and 30 min from the onset of exercise. The [1a]b at 15 min (3.15 mmol·1–1, SEM 0.14) and at 30 min (2.95 mmol·1–1, SEM 0.18) were not significantly different inTh
v trial. However, the [1a]b ofTh
v+ trial significantly increased (P<0.05) from 15 min (3.62 mmol·1–1, SEM 0.36) to 30 min (3.91 mmol·1–1, SEM 0.40). These results indicate thatTh
v gives the [1a]ss,max, at which one can perform sustained exercise without continuous [1a]b accumulation. 相似文献
87.
Changes in VEGF expression and in the vasculature during the growth of early-stage ethylnitrosourea-induced malignant astrocytomas in rats 总被引:2,自引:0,他引:2
F. Yoshimura T. Kaidoh Tetsuo Inokuchi Minoru Shigemori 《Virchows Archiv : an international journal of pathology》1998,433(5):457-463
Vascular endothelial growth factor (VEGF), a potent angiogenic and vascular permeability factor, may be important as a mediator
of brain tumour progression. However, it is still not clear whether VEGF plays a causative role in the early stage of glioma
development. We investigated the relationship between VEGF protein expression (as assayed by immunohistochemistry) and different
morphological parameters reflecting tumour progression (tumour diameter, vascular density and vascular diameter) in tumours
at various stages. As a tumour model, ethylnitrosourea (ENU)-induced rat malignant astrocytoma was used. Tumours were classified
by size and level of vascularity estimated by the von Willebrand factor (vWF) staining. Tumours less than 10 mm in diameter
were designated early stage neoplastic lesions. All 34 early astroglial tumours were found to be VEGF positive. Increase in
the VEGF immunopositive rate of tumour cells correlated significantly with increase in vascular density and vascular diameter.
We suggest that VEGF induces angiogenesis and growth of microvessels, promoting growth of the early stage malignant astrocytoma.
Received: 7 October 1997 / Accepted: 9 June 1998 相似文献
88.
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
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
89.
Kouichi Kashiwase Yoshihide Ishikawa Katsushi Tokunaga Kazue Sawanaka Hatsuya Ohashi Masami Hashimoto Minoru Furuya Ling Lin Tatsuya Akaza Kenji Tadokoro Takeo Juji 《Human immunology》1996,47(1-2):8
Two rare variants of HLA-A locus antigens, tentatively called HLA-A2K and HLA-A9HH, were serologically identified in the Japanese population. A2K and A9HH showed short reaction patterns of a series of anti-A2 and anti-A9 sera, respectively. The latter variant also reacted with some anti-A2 sera. Nucleotide sequences of full-length cDNAs for A2K and A9HH were determined. The results revealed that both antigens are encoded by previously undescribed alleles. The nucleotide sequence of the allele for A2K was identical to that of A*0207 except for a single nucleotide difference in exon 3. The nucleotide sequence of the allele for A9HH was identical to that of A*2402 except for two nucleotides in exon 2. These two nucleotides are shared by all the reported A2 alleles. These sequencing results the allele for A9HH were consistent with the serological cross-reactivity of A9HH with some anti-A2 sera. 相似文献
90.
Uchida M Taida N Kanao M Kagamihara H Kuwajima M 《Rinsho byori. The Japanese journal of clinical pathology》2004,52(7):574-579
We investigated 361 patients with monoclonal gammopathy in whom immunoelectrophoresis was performed (1,037 tests) between 1986 and 2002 at Kagawa Prefectural Central Hospital. In this study, we identified 222 patients with monoclonal gammopathy of undetermined significance (MGUS). Malignant transformation of MGUS to multiple myeloma occurred in 15 patients (6.8%). No significant differences were observed in the means of total protein (TP), albumin (Alb), albumin/globulin ratio (A/G ratio), IgG, IgA, or IgM level in the initial examination between the patients who remained as MGUS and patients with malignant transformation of MGUS. However, the rate of progression to malignancy was high when the levels of normal immunoglobulins other than M protein were below the normal range. Since the number of MGUS cases detected and the number of protein fractionation performed were proportionate, and MGUS was found by protein fractionation in routine tests, protein fractionation is essential for detection of MGUS, and it is necessary to add serum protein fractionation to routine initial examination. In addition, long-term follow-up of patients with monoclonal gammopathy and preparation of a database of patient information are useful for monitoring the outcome. 相似文献