全文获取类型
收费全文 | 5934篇 |
免费 | 315篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 45篇 |
儿科学 | 121篇 |
妇产科学 | 42篇 |
基础医学 | 683篇 |
口腔科学 | 152篇 |
临床医学 | 385篇 |
内科学 | 1623篇 |
皮肤病学 | 61篇 |
神经病学 | 387篇 |
特种医学 | 316篇 |
外科学 | 1003篇 |
综合类 | 35篇 |
预防医学 | 141篇 |
眼科学 | 196篇 |
药学 | 418篇 |
中国医学 | 7篇 |
肿瘤学 | 682篇 |
出版年
2024年 | 8篇 |
2023年 | 73篇 |
2022年 | 176篇 |
2021年 | 243篇 |
2020年 | 94篇 |
2019年 | 152篇 |
2018年 | 212篇 |
2017年 | 170篇 |
2016年 | 191篇 |
2015年 | 186篇 |
2014年 | 227篇 |
2013年 | 268篇 |
2012年 | 415篇 |
2011年 | 498篇 |
2010年 | 249篇 |
2009年 | 202篇 |
2008年 | 379篇 |
2007年 | 379篇 |
2006年 | 374篇 |
2005年 | 353篇 |
2004年 | 324篇 |
2003年 | 285篇 |
2002年 | 299篇 |
2001年 | 56篇 |
2000年 | 40篇 |
1999年 | 36篇 |
1998年 | 42篇 |
1997年 | 35篇 |
1996年 | 38篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 9篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 20篇 |
1985年 | 11篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1973年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有6297条查询结果,搜索用时 15 毫秒
11.
Yasuyuki Yamashita Katsuhiko Mitsuzaki Yi Tang Tomohiro Namimoto Mutsumasa Takahashi 《Journal of magnetic resonance imaging : JMRI》1997,7(4):623-628
MR angiography (MRA) was performed in 50 consecutive subjects (mean age, 59 years), who had been referred for abdominal MRA, on a 1.5-T superconductive unit that used a body phased-array coil. Three breath-hold three-dimensional sequences were evaluated both in phantom and clinical studies: (a) standard fast three-dimensional gradient-echo sequence (TR = 15, TE = 6; imaging time, 32 seconds), (b) ultrafast three-dimensional gradient-echo sequence (TR = 8.2, TE = 3; imaging time, 18 seconds), and (c) ultrafast magnetization-prepared (MP) rapid acquisition gradient echo (RAGE) (TR = 5.8, TE = 2.9, inversion time [TI] = 20; imaging time, 15 seconds). The initial 30 patients were randomized into three groups by three separate sequences. For the remaining 20 patients, ultrafast-gradient-echo and ultrafast MP-RAGE sequences were performed. Conventional angiography was performed on 36 patients. Signal measurements of the phantom and clinical images of the aorta, visceral branches of the aorta, iliac arteries, inferior vena cavae, and portal veins were performed. The overall image quality and background fatty tissue contrast of the vessels were rated subjectively. Comparison of images between MRA and conventional angiography also was performed. The contrast between the vessels and background fatty tissue was significantly higher in the ultrafast MP-RAGE sequence in both quantitative and qualitative analysis, and image-quality ultrafast MP-RAGE was superior to the other two sequences (P < .01). The aorta and iliac arteries could be visualized in all pulse sequences, and abnormalities of these vessels were diagnosed correctly. The renal artery was visualized more clearly with the two ultrafast sequences. 相似文献
12.
13.
Vav3 modulates B cell receptor responses by regulating phosphoinositide 3-kinase activation. 总被引:7,自引:0,他引:7
Kazunori Inabe Masamichi Ishiai Andrew M Scharenberg Norman Freshney Julian Downward Tomohiro Kurosaki 《The Journal of experimental medicine》2002,195(2):189-200
To elucidate the mechanism(s) by which Vav3, a new member of the Vav family proteins, participates in B cell antigen receptor (BCR) signaling, we have generated a B cell line deficient in Vav3. Here we report that Vav3 influences phosphoinositide 3-kinase (PI3K) function through Rac1 in that phosphatidylinositol-3,4,5-trisphosphate (PIP3) generation was attenuated by loss of Vav3 or by expression of a dominant negative form of Rac1. The functional interaction between PI3K and Rac1 was also demonstrated by increased PI3K activity in the presence of GTP-bound Rac1. In addition, we show that defects of calcium mobilization and c-Jun NH2-terminal kinase (JNK) activation in Vav3-deficient cells are relieved by deletion of a PIP3 hydrolyzing enzyme, SH2 domain-containing inositol polyphosphate 5'-phosphatase (SHIP). Hence, our results suggest a role for Vav3 in regulating the B cell responses by promoting the sustained production of PIP3 and thereby calcium flux. 相似文献
14.
Tadashi Kano MD Toshiro Koga Kuniyasu Souda Yoshishige Abe Tomohiro Yonemura Naokata Oka Kiyoshi Inokuchi 《Surgery today》1987,17(4):269-275
The usefulness of carcinoembryonic antigen (CEA) as an indicator for recurrence and a guide to the treatment was evaluated
from a retrospective analysis of 88 patients with recurrent gastric cancer. Sixty-two of these patients (70.5 per cent), 25
of whom had a preoperative positive assay, and 37 a negative assay, had elevated levels of CEA after disease progression.
Averaged CEA level in patients with liver metastasis was significantly higher (872 ng/ml) than in those with peritoneal metastasis
(68 ng/ml), with lymph node metastasis (103 ng/ml) or with local metastasis (93 ng/ml) (p<0.01). An elevation of CEA was found
prior to the clinical manifestation of recurrence, and the average lead time was 4 months. In 25 patients with a lead time
of more than 4 months, survival time after CEA elevation was 13.3 months, which was longer than the 6.5 months of 28 patients
with less than 4 months. Thirty-seven of the 88 patients were treated after recurrence. The average survival period after
the detection of recurrence was 9.4 months in patients with surgical treatments followed by chemotherapy, 5.9 months in those
with chemotherapy alone and 3.8 months in those with surgery alone. The average survival period of 26 patients with positive
CEA assays in recurrence was 5.1 months longer than of patients with negative assays. This fact suggested that early detection
of recurrence followed by various treatments, in the elevated CEA group, contributes to favorable results. 相似文献
15.
The purpose of this study was to investigate the histogenesis of experimental tumors in the rat esophagus. Thirty rats received 0.0015% N-methyl-N-amylnitrosamine (MNAN) in the drinking water for 12 weeks. Another 30 rats received tap water. All rats then received tap water until sacrifice. Rats from each group were sacrificed immediately after MNAN administration, four weeks after, and eight weeks after. One hour before sacrifice, [3H]TdR was injected by tail vein to label proliferating cells. The entire esophagus and stomach were removed and processed for light and electron microscopy and autoradiography. The overall frequency of esophageal tumors after MNAN was 83% and did not differ significantly among the three experimental groups. Tumors were primarily papillomas and squamous cell carcinomas and occurred with equal frequency in the upper, middle, and lower thirds of the esophagus. No tumors were found in the squamous-lined forestomach. Electron microscopy revealed abundant tonofilaments, free ribosomes, and mitochondria accompanied by vacuoles. By autoradiography, esophageal epithelial proliferation was markedly stimulated in nontumorous mucosa from all three experimental groups. We conclude that MNAN ingestion for 12 weeks reliably produces papillomas and squamous cell carcinomas throughout the rat esophagus, but not in the squamouslined forestomach, and that MNAN stimulated marked epithelial proliferation which is accompanied by thickening of the epithelium in nontumorus esophageal mucosa. 相似文献
16.
Masatoshi Kubo Shigeharu Moriyama Tomohiro Nogami Tadayoshi Kunitomo Sugato Nawa 《The Japanese Journal of Thoracic and Cardiovascular Surgery》2004,52(9):435-438
This paper presents a case of intercostal hemangioma, in which a complete surgical resection was accomplished based upon a
tentative diagnosis provided by magnetic resonance imaging (MRI). A 27-year-old man visited our hospital for the evaluation
of chest pain and shortness of breath after exertion. Computed tomography showed a soft tissue mass, 5.5×3.5 cm in size, arising
from the right lateral 7th intercostal space. Dynamic MRI showed that the mass was enhanced rapidly in the early phase and
that this early enhancement was maintained during the delayed phase, which was compatible with a diagnosis of intercostal
hemangioma. The patient underwent surgery, and a complete resection of the tumor with the right 7th and 8th ribs and their
intercostal muscles was accomplished. Histopathological examination confirmed the diagnosis of intramuscular hemangioma of
the large-vessel type. Presently, 6 months after the operation, the patient is doing well, without any evidence of local recurrence. 相似文献
17.
Tomohiro Kondo Kazuhiro Sentani Naohide Oue Kazuhiro Yoshida Hirofumi Nakayama Wataru Yasui 《Pathobiology》2004,71(1):19-25
OBJECTIVES: RHOC, a member of the RAS-related small GTPase protein family, regulates cytoskeletal structures and has the potential to transform cultured cells. It has recently been reported that RHOC contributes to the metastatic phenotype of melanoma cells. The purpose of this study was to clarify its biological relevance to gastric carcinogenesis and metastasis. METHODS: We examined the expression of RHOC by quantitative RT-PCR in 51 cases of gastric carcinoma tissues from prior surgical cases (intestinal type: 24 cases, diffuse type: 27 cases) and in 8 gastric carcinoma cell lines. RESULTS: RHOC expression levels in primary tumors were significantly higher in cases with metastasis than in those without metastasis (p = 0.0202; Mann-Whitney U test). RHOC expression levels in primary tumor and their metastatic tumors were significantly higher than their corresponding nonneoplastic mucosa (p = 0.0357, and 0.0173, respectively; Wilcoxon signed rank test). RHOC mRNA expression was confirmed in the gastric carcinoma cell lines. CONCLUSION: Our findings suggest that elevated expression of the RHOC gene may be involved in the metastasis of gastric carcinomas and may be a good genetic marker for the prediction of a metastatic potential. 相似文献
18.
19.
Yoshiyuki Kaneko Tomohiro Nakayama Kosuke Saito Akihiko Morita Ichiro Sato Aya Maruyama Masayoshi Soma Teruyuki Takahashi Naoyuki Sato 《Hypertension research》2006,29(9):665-671
The risk of cerebral infarction (CI) in an individual is dependent on the interplay between genetic risk factors and environmental influences. Binding of thromboxane A2 (TXA2) to its receptor (TP) modulates thrombosis/hemostasis and plays a significant role in the pathogenesis of CI. The aim of the present study was to investigate the relationship between human TP gene single nucleotide polymorphisms (SNPs) and haplotypes and CI in a Japanese population. A genetic association study was performed in 194 CI patients and 365 non-CI subjects by specifically characterizing 6 SNPs in the human TP gene (rs2271875, rs768963, rs2238634, rs11085026, rs4523 and rs4806942). Analysis demonstrated that there were significant differences in the overall distribution of genotypes and dominant or recessive models of rs2271875 and rs768963 between the CI and the non-CI groups. Multiple logistic regression analysis revealed that the C allele of rs768963 was significantly associated with CI (p = 0.029), even after adjusting for confounding factors (odds ratio: 2.41). Further, the C-T-C haplotype of rs768963-rs2238634-rs4806942 was significantly more frequent in the CI group (23.0%) than in the non-CI group (17.7%). These results suggest that specific SNPs and haplotypes may have utility as genetic markers for the risk of CI and that TP or a neighboring gene is associated with the increased susceptibility to CI. 相似文献