全文获取类型
收费全文 | 5608篇 |
免费 | 232篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 91篇 |
妇产科学 | 30篇 |
基础医学 | 665篇 |
口腔科学 | 82篇 |
临床医学 | 350篇 |
内科学 | 1466篇 |
皮肤病学 | 78篇 |
神经病学 | 323篇 |
特种医学 | 235篇 |
外科学 | 1078篇 |
综合类 | 30篇 |
预防医学 | 213篇 |
眼科学 | 130篇 |
药学 | 326篇 |
中国医学 | 10篇 |
肿瘤学 | 722篇 |
出版年
2023年 | 38篇 |
2022年 | 104篇 |
2021年 | 179篇 |
2020年 | 73篇 |
2019年 | 100篇 |
2018年 | 123篇 |
2017年 | 89篇 |
2016年 | 131篇 |
2015年 | 129篇 |
2014年 | 183篇 |
2013年 | 250篇 |
2012年 | 368篇 |
2011年 | 371篇 |
2010年 | 224篇 |
2009年 | 182篇 |
2008年 | 309篇 |
2007年 | 381篇 |
2006年 | 321篇 |
2005年 | 326篇 |
2004年 | 361篇 |
2003年 | 343篇 |
2002年 | 323篇 |
2001年 | 76篇 |
2000年 | 74篇 |
1999年 | 67篇 |
1998年 | 79篇 |
1997年 | 75篇 |
1996年 | 52篇 |
1995年 | 46篇 |
1994年 | 37篇 |
1993年 | 33篇 |
1992年 | 44篇 |
1991年 | 39篇 |
1990年 | 32篇 |
1989年 | 31篇 |
1988年 | 26篇 |
1987年 | 43篇 |
1986年 | 17篇 |
1985年 | 36篇 |
1984年 | 21篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有5883条查询结果,搜索用时 15 毫秒
41.
The Serum Factor from Patients with Ulcerative Colitis that Induces T Cell Proliferation in the Mouse Thymus Is Interleukin-7 总被引:3,自引:0,他引:3
Mamoru Watanabe Noriaki Watanabe Yasushi Iwao Haruhiko Ogata Takanori Kanai Yoshitaka Ueno Masaharu Tsuchiya Hiromasa Ishii Sadakazu Aiso Sonoko Habu Toshifumi Hibi 《Journal of clinical immunology》1997,17(4):282-292
The disturbance of immune regulatory T cells is related to the pathogenesis of ulcerative colitis. Here we demonstrated and characterized the serum factor from ulcerative colitis patients that induced proliferation of intrathymic T cells. The factor isolated from the patient sera by a combination of gel filtration and anion-exchange chromatography induced proliferation of CD4+CD8– intrathymic T cells in the organ-cultured embryonic mouse thymus. Purification and amino acid sequence analysis of the serum factor demonstrated that the N-terminal 12 sequence was homologous to that of interleukin-7. SDS-PAGE and Western blot confirmed that purified serum factor was interleukin-7. Enzyme immunoassay demonstrated that the serum interleukin-7 concentration was significantly increased in the patients. PCR and Southern blot hybridization demonstrated that interleukin-7 mRNA expression was increased in the thymus tissues from patients but decreased in the colonic mucosa. Since interleukin-7 is a crucial cytokine for proliferation and differentiation of T cells in the thymus, the present study indicates that interleukin-7 may contribute to the disturbance of immune regulatory T cells in ulcerative colitis. 相似文献
42.
Honda T Ota H Arai K Hayama M Fujimoto K Yamazaki Y Haniuda M 《Virchows Archiv : an international journal of pathology》2002,441(1):47-52
The etiology of usual interstitial pneumonia (UIP), a progressive lung disease, remains unclear. We examined alveolar structure in UIP three-dimensionally. Lung biopsy specimens from five patients with idiopathic pulmonary fibrosis were used. Sections 150-microm thick were stained with elastica solution for elastic fibers, with alpha-smooth muscle actin antibody for myofibroblasts, with anti-Thomsen-Friedenreich antibody for type-II pneumocytes and with anti-CD34 antibody for blood vessels. We examined them three-dimensionally using a laser confocal microscope or light microscope. In the fibrotic lesions, the thick elastic fibers forming the alveolar framework were not particularly dense considering the reduction in alveolar volume. Near the fibrotic lesions, some of the thin elastic fibers in the alveolar wall were slightly sinuous and ended with rounded tips. Type-II pneumocytes had proliferated and were distributed uniformly over the alveolar surface. Smooth muscle actin filaments were detected only around the alveolar orifice. These findings show that in UIP destruction of the elastic fiber framework of the alveoli may lead to irreversible focal alveolar collapse after damage to the alveolar epithelial cells, and proliferation of type-II pneumocytes may be involved with this elastolysis. 相似文献
43.
Jun-ichi Kadokawa Yoshitaka Matsumura Shiro Kobayashi 《Macromolecular chemistry and physics.》1994,195(11):3689-3698
This paper describes a new ring-opening-closing alternating copolymerization (ROCAC) of 2-methyl-2-oxazoline (five-membered cyclic imino ether, 1 ) with N-methyldiacrylamide ( 2 ). The reaction of a 1 : 1 monomer feed ratio proceeded without any added catalyst to give an alternating copolymer 3 having two structural units formed by ring-opening and ring-closing (cyclization). The structure of copolymer 3 was determined by 1H, 13C NMR, and IR spectroscopies. The extent of cyclization was at most 65%. The copolymerization was reasonably explained by a mechanism of propagation via zwitterion intermediates. 相似文献
44.
Nagai Y Fujikake N Ohno K Higashiyama H Popiel HA Rahadian J Yamaguchi M Strittmatter WJ Burke JR Toda T 《Human molecular genetics》2003,12(11):1253-1259
Polyglutamine (polyQ) diseases are a growing class of inherited neurodegenerative diseases including Huntington's disease, which are caused by abnormal expansions of the polyQ stretch in each unrelated disease protein. The expanded polyQ stretch is thought to confer toxic properties on the disease proteins through alteration of their conformation leading to pathogenic protein-protein interactions including oligomerization and/or aggregation. Hypothesizing that molecules with selective binding affinity to the expanded polyQ stretch may interfere with the pathogenic properties, we previously identified Polyglutamine Binding Peptide 1 (QBP1) from combinatorial peptide phage display libraries. We show here that a tandem repeat of the inhibitor peptide QBP1, (QBP1)(2), significantly suppresses polyQ aggregation and polyQ-induced neurodegeneration in the compound eye of Drosophila polyQ disease models, which express the expanded polyQ protein under the eye specific promoter. Most importantly, (QBP1)(2) expression dramatically rescues premature death of flies expressing the expanded polyQ protein in the nervous system, resulting in the dramatic increase of the median life span from 5.5 to 52 days. These results suggest that QBP1 can prevent polyQ-induced neurodegeneration in vivo. We propose that QBP1 prevents polyQ oligomerization and/or aggregation either by altering the toxic conformation of the expanded polyQ stretch, or by simply competing with the expanded polyQ stretches for binding to other expanded polyQ proteins. The peptide inhibitor QBP1 is a promising candidate with great potential as a therapeutic molecule against the currently untreatable polyQ diseases. 相似文献
45.
46.
The occurrence of a post-traumatic epidural hematoma in two patients with long-standing arrested hydrocephalus is reported. There was a relatively long interval between the head injury and the onset of symptoms. The large hematoma was accommodated by the decrease in size of the markedly dilated ventricles. This report stresses the possibility of the presence of an epidural hematoma in the management of head injury in patients with long-standing arrested hydrocephalus. 相似文献
47.
To determine if clinically observed disorders in heme biosynthetic enzymes, known as sporadic porphyria cutanea tarda (PCT), could be reproduced in experimental animals, male Fischer rats were treated with ethanol, estrogen and hexachlorobenzene (HCB). A series of heme biosynthetic enzymes were assayed. In the rats given free access to 8% ethanol-drinking water for 15 weeks, -aminolevulinate (ALA) dehydratase was significantly reduced in erythrocytes. In the liver, ALA synthetase and uroporphyrinogen (UROgen) decarboxylase activities remained unchanged. In bone marrow cells, these activities did not change markedly. In the rats treated with estrogen (1 mg estrioltripropionate /rat/week, IM), no body weight gain was observed during the treatment for 15 weeks and urinary ALA excretion increased to 1.7 fold over normal level. In the liver, a significant increase was observed in the activity of ALA dehydratase, but other enzymes remained within the normal level. In bone marrow cells and erythrocytes, ALA dehydratase was also increased. ALA synthetase increased only in bone marrow cells to 2.1 times higher than the control level. In rats fed 0.3% HCB-diet for 8 weeks, urinary excretion of ALA, coproporphyrin and uroporphyrin increased to 2.4, 3.3 and 3.8 times higher than the controls, respectively. In the liver, an increase was observed in ALA synthetase, while a decrease was observed in ALA dehydratase and UROgen decarboxylase. In bone marrow cells and erythrocytes, ALA dehydratase was reduced and activities of other enzymes did not show any changes.These results indicate that alcohol, estrogen and HCB do not produce phenomena similar to those observed clinically in PCT. 相似文献
48.
Fumie Takewaki Hanako Nakajima Daiki Takewaki Yoshitaka Hashimoto Saori Majima Hiroshi Okada Takafumi Senmaru Emi Ushigome Masahide Hamaguchi Masahiro Yamazaki Yoshiki Tanaka Shunji Nakajima Hiroshi Ohno Michiaki Fukui 《Nutrients》2021,13(6)
The aim of this research was to reveal the characteristics of gut microbiome altered by acarbose intervention in Japanese patients with type 2 diabetes (T2D) and its possible association with habitual dietary intake. Eighteen patients with T2D were administered acarbose for four weeks. The abundances of two major phyla, namely Actinobacteria and Bacteroidetes, were reciprocally changed accompanied by the acarbose intervention. There were also significant changes in the abundances of ten genera, including the greater abundance of Bifidobacterium, Eubacterium, and Lactobacillus and the lower abundance of Bacteroides in the group after the intervention than that before the intervention. Hierarchical clustering of habitual dietary intake was performed based on the pattern of changes in the gut microbiota and were classified into distinct three clusters. Cluster I consisted of sucrose, cluster II mainly included fat intake, and cluster III mainly included carbohydrate intake. Moreover, the amount of change in Faecalibacterium was positively correlated with the intake of rice, but negatively correlated with the intake of bread. The intake of potato was negatively correlated with the amount of change in Akkermansia and Subdoligranulum. Acarbose altered the composition of gut microbiome in Japanese patients with T2D, which might be linked to the habitual dietary intake. 相似文献
49.
50.
Hiroshi Ninomiya Makito Watanabe Kazunari Kamimura 《The Journal of foot and ankle surgery》2021,60(1):218-220
Avulsion fractures of the calcaneal tuberosity, although relatively uncommon, occur more frequently in patients with osteoporosis and in the elderly. The results of closed manipulation are poor in these fractures, usually requiring open reduction and internal fixation. However, it is difficult to fix the bone fragment rigidly, because the avulsed bone fragment is small and thin, and the bone quality of the calcaneal body in the elderly is poor. Hence, it is necessary to limit prolonged weight-bearing after the operation. We performed an innovative surgical procedure of suture fixation to the anchor screw in four cases, following which earlier postoperative rehabilitation with full weight-bearing walking and range of motion exercises was possible, and bony union was achieved without repeated displacement of the fragment in all patients. We believe this technique would prove useful in surgical management of calcaneal tuberosity avulsion fractures. 相似文献