全文获取类型
收费全文 | 44601篇 |
免费 | 2164篇 |
国内免费 | 271篇 |
专业分类
耳鼻咽喉 | 266篇 |
儿科学 | 919篇 |
妇产科学 | 558篇 |
基础医学 | 5621篇 |
口腔科学 | 1083篇 |
临床医学 | 2975篇 |
内科学 | 11531篇 |
皮肤病学 | 764篇 |
神经病学 | 3569篇 |
特种医学 | 1931篇 |
外科学 | 7325篇 |
综合类 | 175篇 |
预防医学 | 1178篇 |
眼科学 | 710篇 |
药学 | 3154篇 |
中国医学 | 93篇 |
肿瘤学 | 5184篇 |
出版年
2023年 | 276篇 |
2022年 | 533篇 |
2021年 | 937篇 |
2020年 | 497篇 |
2019年 | 763篇 |
2018年 | 909篇 |
2017年 | 703篇 |
2016年 | 918篇 |
2015年 | 951篇 |
2014年 | 1311篇 |
2013年 | 1506篇 |
2012年 | 2374篇 |
2011年 | 2700篇 |
2010年 | 1442篇 |
2009年 | 1286篇 |
2008年 | 2260篇 |
2007年 | 2462篇 |
2006年 | 2437篇 |
2005年 | 2462篇 |
2004年 | 2360篇 |
2003年 | 2303篇 |
2002年 | 2297篇 |
2001年 | 1143篇 |
2000年 | 1100篇 |
1999年 | 1136篇 |
1998年 | 608篇 |
1997年 | 496篇 |
1996年 | 467篇 |
1995年 | 374篇 |
1994年 | 342篇 |
1993年 | 316篇 |
1992年 | 766篇 |
1991年 | 672篇 |
1990年 | 685篇 |
1989年 | 648篇 |
1988年 | 560篇 |
1987年 | 492篇 |
1986年 | 486篇 |
1985年 | 435篇 |
1984年 | 313篇 |
1983年 | 261篇 |
1982年 | 118篇 |
1981年 | 122篇 |
1980年 | 110篇 |
1979年 | 249篇 |
1978年 | 157篇 |
1977年 | 142篇 |
1975年 | 109篇 |
1972年 | 112篇 |
1971年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Hironari Takaishi Osamu Nemoto Masanobu Shiota Toshiyuki Kikuchi Harumoto Yamada Masaaki Yamagishi Yutaka Yabe 《Journal of orthopaedic research》1997,15(4):528-538
To clarify phenotypic alterations of intervertebral disc cells during the repair process, we cloned partial type-II collagen cDNA from rabbits and analyzed the level of expression of type-II collagen mRNA in disc degeneration. An animal model was created by surgical denucleation of rabbit intervertebral discs through, an extraperitoneal approach. Eight animals each from an experimental and a control group were killed at 2, 4, 8, or 16 weeks postoperatively, and the disc samples were used for this study. Round chondrorcyte-like cells that filled the herniated space showed intense signal of type-II collagen mRNA and significant pericellular immunostaining of type-II collagen but no clear staining of type-I collagen. Northern. blot analysis revealed that the expression of type-II collagen mRNA of the repair disc cells was transiently increased at 4 weeks postoperatively. The cells were able to change their morphology in response to mechanical stimulation by surgical denucleation and to induce a significant increase in the gene expression of type-II collagen at an early phase of disc degeneration. The present results indicate the transient enhancement of repair activity in the degenerative process of injured fibrocartilage. 相似文献
82.
T Iwama H Yamada T Andoh N Sakai S Era M Sogami K Kuwata H Watari 《Magnetic resonance in medicine》1992,25(1):78-84
The spin-lattice relaxation time (T1) of water protons and the cross-relaxation time (TIS) between irradiated protein protons and observed water protons were measured in order to study water-macromolecular interactions in ischemic rat brain tissues. Tissues were obtained by bilateral common carotid artery occlusion from stroke-prone spontaneously hypertensive rats. Water, Na, and K contents were measured in ischemic brain tissue at the same time. Water and Na content increased while the TIS value and K content decreased following ischemic insults. The T1 value did not change until 180 min after ischemia had been induced. Changes in the TIS value occurred earlier than changes observed for the T1 value, water, and electrolyte contents. Results indicate that the value of TIS may be useful for detecting cerebral ischemia and that the physical structure of water-macromolecular interaction may be altered soon after ischemic onset in brain tissue. 相似文献
83.
K Nishi M Yamada D Morishita Y Nakamura Y Murata M Fujioka S Muramoto S Murakami K Sasaki M Yasui 《Nihon Kyōbu Shikkan Gakkai zasshi》1991,29(7):904-908
A rare case of a 25-year-old man with pulmonary aspergillosis is reported. Pulmonary bulla and eosinophilic pneumonia in the right upper lobe were diagnosed by chest roentgenogram and transbronchial lung biopsy. Because the patient developed infective bullae during steroid therapy, we performed transcutaneous thoracic drainage and right upper lobectomy. The resected lung tissue contained numerous hyphae of Aspergillus. Around the hyphae of Aspergillus, granulomatous reaction and eosinophilic infiltration were observed. Antibodies against Aspergillus were detected in the serum of the patient. The number of peripheral blood eosinophils decreased after right upper lobectomy. These findings suggest that pulmonary bullae and eosinophilic pneumonia may be a rare manifestation of pulmonary aspergillosis. 相似文献
84.
Five latissimus dorsi musculocutaneous flaps (LD flap) were used for reconstruction with prostheses after resection of tumors between 1984 and 1991 in our hospital. Bony structures were reconstructed with prostheses and in three cases autoclaved autobone grafts were also needed. The prostheses and adjacent grafts were then wrapped by the LD flaps. Tumor sites included one humerus, two thighs, and two knees. All but one case healed primarily. The sole case of infection was successfully treated with debridement and irrigation. Due to the LD flaps' plentiful blood supply, we believe infection of the prosthetics can be avoided and good clinical results can be achieved using the flap with autoclaved autograft prosthetic composite reconstruction. © 1994 Wiley-Liss, Inc. 相似文献
85.
86.
87.
Hiroyuki Kumamoto Nobuhiro Takahashi Kiyoshi Ooya 《Journal of oral pathology & medicine》2004,33(6):360-367
BACKGROUND: To clarify the roles of rat sarcoma (Ras)/mitogen-activated protein kinase (MAPK) signaling pathway in oncogenesis and cytodifferentiation of odontogenic tumors, K-Ras gene status and expression of Ras, Raf1, MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK)1, and ERK1/2 proteins were analyzed in ameloblastomas as well as in tooth germs. METHODS: Paraffin sections of 10 tooth germs and 46 benign and 6 malignant ameloblastomas were examined immunohistochemically for the expression of K-Ras, Raf1, MEK1, and ERK1/2. Frozen tissue samples of 22 benign ameloblastomas and 1 malignant (metastasizing) ameloblastoma were analyzed by direct DNA sequencing to detect K-Ras gene alteration. RESULTS: Immunohistochemical reactivity for K-Ras, Raf1, MEK1, and ERK1/2 was detected in both normal and neoplastic odontogenic epithelium, and these molecules were reactive chiefly with odontogenic epithelial cells neighboring the basement membrane. Plexiform ameloblastomas showed slightly stronger expression of these Ras/MAPK signaling molecules than follicular ameloblastomas. Keratinizing cells and granular cells showed decreased reactivity for the signaling molecules. Basal cell ameloblastomas showed slightly stronger reactivity for the signaling molecules than did the other subtypes. K-Ras immunoreactivity in malignant ameloblastomas was lower than that in dental lamina of tooth germs. Direct DNA sequencing showed a GGT to GCT point mutation at codon 12 of K-Ras gene in one ameloblastoma. Conclusion: Expression of K-Ras, Raf1, MEK1, and ERK1/2 in tooth germs and ameloblastomas suggests that Ras/MAPK signaling pathway functions to regulate cell proliferation and differentiation in both normal and neoplastic odontogenic epithelium. K-Ras gene status implied that K-Ras mutations might play a minor role in oncogenesis of odontogenic epithelium. 相似文献
88.
K Yamada Y Ushio T Hayakawa N Arita T Y Huang M Nagatani N Yamada H Mogami 《Cancer research》1987,47(8):2123-2128
To assess the rationale of intraarterial (i.a.) 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea chemotherapy, distribution of 14C-labeled 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)- 3-nitrosourea in rat glioma was studied after i.a. or i.v. infusion. Immediately after infusion, the tumor located in the hemisphere of intracarotid infusion received 4.6-fold higher radioactivity than the tumor located contralaterally to intracarotid infusion and 2.8-fold higher radioactivity than i.v. infusion. The difference was kept up to 30 min after i.a. infusion. Autoradiographic observation indicated rather uniform distribution of the tracer in the central portion of i.a. infusion. However, in the periphery of i.a. infusion, distribution of the tracer was nonhomogenous. The results indicate that i.a. 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea chemotherapy is useful when the tumor has high blood flow and is located in the center of an infused area. 相似文献
89.
90.
Radiotherapy was applied to 14 esophageal carcinomas with respiratory tract fistulas using various treatment regimens. Closure of the fistulas was observed in four cases after irradiation at a daily dose of 1.5 Gy. The period of closure was transient in two cases but long-term in the other two. One long-term closure case underwent low-dose rate telecobalt therapy (LDRT)(1 Gy per hour, 7 Gy per day; a total dose of 28 Gy) as a boost. His cancer has been well controlled and he is still alive without recurrence at 74 months after fistula formation. 相似文献