全文获取类型
收费全文 | 8906篇 |
免费 | 445篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 52篇 |
儿科学 | 192篇 |
妇产科学 | 114篇 |
基础医学 | 1208篇 |
口腔科学 | 284篇 |
临床医学 | 616篇 |
内科学 | 2078篇 |
皮肤病学 | 279篇 |
神经病学 | 984篇 |
特种医学 | 201篇 |
外科学 | 1040篇 |
综合类 | 39篇 |
现状与发展 | 1篇 |
预防医学 | 449篇 |
眼科学 | 289篇 |
药学 | 706篇 |
中国医学 | 16篇 |
肿瘤学 | 846篇 |
出版年
2023年 | 63篇 |
2022年 | 137篇 |
2021年 | 200篇 |
2020年 | 127篇 |
2019年 | 175篇 |
2018年 | 173篇 |
2017年 | 149篇 |
2016年 | 207篇 |
2015年 | 205篇 |
2014年 | 252篇 |
2013年 | 310篇 |
2012年 | 550篇 |
2011年 | 644篇 |
2010年 | 347篇 |
2009年 | 272篇 |
2008年 | 514篇 |
2007年 | 545篇 |
2006年 | 513篇 |
2005年 | 546篇 |
2004年 | 533篇 |
2003年 | 490篇 |
2002年 | 486篇 |
2001年 | 131篇 |
2000年 | 135篇 |
1999年 | 139篇 |
1998年 | 109篇 |
1997年 | 57篇 |
1996年 | 78篇 |
1995年 | 74篇 |
1994年 | 51篇 |
1993年 | 48篇 |
1992年 | 110篇 |
1991年 | 84篇 |
1990年 | 104篇 |
1989年 | 93篇 |
1988年 | 95篇 |
1987年 | 88篇 |
1986年 | 84篇 |
1985年 | 64篇 |
1984年 | 57篇 |
1983年 | 33篇 |
1982年 | 27篇 |
1981年 | 17篇 |
1980年 | 29篇 |
1979年 | 32篇 |
1978年 | 23篇 |
1975年 | 16篇 |
1974年 | 20篇 |
1968年 | 16篇 |
1967年 | 16篇 |
排序方式: 共有9394条查询结果,搜索用时 15 毫秒
91.
Maekawa M; Sugano K; Kashiwabara H; Ushiama M; Fujita S; Ohkura H; Kakizoe T 《Japanese journal of clinical oncology》1998,28(6):383-387
BACKGROUND: Ornithine decarboxylase (ODC; EC 4.1.1.17) is the first
rate-limiting enzyme in the biosynthesis of polyamines. ODC protein has a
characteristic amino acid sequence, the PEST sequence, which is related to
the enzyme's rapid degradation. ODC cDNA prepared from human hepatoma
tissues has been reported to show nonsense or missense mutations. METHODS:
We examined somatic mutations of ODC cDNA by RT-PCR-SSCP analysis and mRNA
expressions by RT-PCR in 50 colorectal cancer tissues to investigate the
involvement of ODC gene alterations in colorectal cancers. RESULTS:
Increased expression of the ODC gene was observed in 36 cases (86%) out of
the 42 examined by RT-PCR. In one case, a missense mutation was found in
the cancer tissue but not in normal mucosa. The missense mutation from Asp
to Asn at codon 424, in the PEST region, possibly stabilizes the ODC
protein. In colorectal cancer, replication error and a germline mutation in
hMSH2 gene were observed. CONCLUSIONS: The missense mutation at codon 424
is speculated to be a cause of stabilization and a passenger mutation owing
to the mutator phenotype. Since only one of 50 colorectal cancers exhibited
a missense mutation of the ODC gene, mutations in ODC gene are not frequent
in colorectal cancer. The increased expression of the ODC gene was noted in
86% of colorectal cancer tissues by RT-PCR, however, it was not due to
point mutations in ODC coding exons.
相似文献
92.
目的了解心电图同期CT脑血管造影(CTA)技术对于未破裂动脉瘤的小泡样突起诊断的准确性。方法2004年间对15例患者进行了心电图同期CTA检查。结果其中10例患者在心电图同期CTA图像上发现有搏动部位存在,提示动脉瘤上有小泡样突起,手术中也有同样发现。切除的15例动脉瘤标本组织学检查均发现肌层和内弹力层部分或完全缺失,而有小泡的10例动脉瘤中发现胶原层减少,这与小泡样突起的存在相吻合。结论心电图同期CTA可用于未破裂动脉瘤的小泡样突起的诊断,其准确性可用标本的组织学检查加以证明。 相似文献
93.
Postinfarction ventricular septal rupture is still a surgically challenging situation with high operative mortality. We report a case of ventricular septal rupture in a 75-year-old woman successfully treated with our newly devised technique, in which a pliable large septal path is fixed with transmural sutures placed in posterior left ventricular free wall and anterior ventriculotomy closing sutures, thus covering the septal wall almost entirely. Our method may simplify the operation and reduce the risk of residual leakage. 相似文献
94.
Midori Yoshida Shin-Ichi Katsuda Dai Nakae Akihiko Maekawa 《Food and chemical toxicology》2004,42(4):667-676
A chronic combined toxicity and carcinogenicity study of S-170, a sucrose fatty acid ester, was performed in male and female F344 rats. S-170 was given ad libitum in the diet at levels of 0, 1.25, 2.5 or 5% to 10 rats/sex/group for 12 months to determine chronic toxicity and 0, 2.5 or 5% to 50 rats/sex/group for two years in the carcinogenicity study. Treatment with S-170 exerted no effect on survival in either sex. In the 12-month chronic toxicity study, no treatment-related effects on body weights, or hematological, blood biochemical, urinary and pathological parameters were demonstrated in any of the treated groups. In the carcinogenicity study, S-170 did not cause any dose-related significant increase in the incidences of tumors in any organs or tissues. Taken together, the results clearly demonstrate that S-170 has neither toxic nor carcinogenic activity in F344 rats under the conditions of the study. No observed adverse effect levels (NOAELs) calculated from the 12-month chronic toxicity and carcinogenicity study were 2.37 g/kg/day in males and 2.80 g/kg/day in females, and 2.12 g/kg/day in males and 2.42 g/kg/day in females, respectively. 相似文献
95.
96.
BACKGROUND AND AIMS: Bacterial translocation is precipitated by an increase in bacteria or endotoxin, depression of the membrane barrier, and an increase in mucosal permeability. Plaunotol is a mucosal protective agent, and observed to have a strong suppressive effect on superoxide production. In this study, the effect of plaunotol on bacterial translocation was examined using the model of ischemia and reperfusion. METHOD: Male Sprague Dawley rats were used to create the following model for evaluation of bacterial translocation: (i) the control group; (ii) the preventive dose group (plaunotol 30 mg/kg/day one week before surgery); (iii) the therapeutic dose group (plaunotol 30 mg/kg/day one week after surgery); and (iv) the full dose group (plaunotol 30 mg/kg/day one week before surgery and one week after surgery). Bacterial translocation was assessed as the blood concentration of the endotoxin. RESULTS: In the control group, the endotoxin increased significantly 3 days postsurgery (13.7+/-5.6 pg/ml) compared with before surgery (1.1+/-0.1 pg/ml). In the preventive and full-dose groups, the erndotoxin decreased significantly 3 days postsurgery (4.4+/-2.8 pg/ml, 5.7+/-2.7 pg/ml, respectively) compared with that of the control group. CONCLUSION: Plaunotol in the preventive and full-dose groups decreased the endotoxin. This suggests that plaunotol is one of the protectors for bacterial translocation. 相似文献
97.
A 47-year-old Japanese woman with a history of epigastric pain and a recent episode of acute pancreatitis (back pain, nausea, and vomiting) and anemia was found to have a pancreatic cyst of the tail on CT-scan and ultrasonography. Especially, ultrasonography revealed the papillary solid lesion in the cyst. With the tentative diagnosis of a cystic neoplasm, distal pancreatectomy was performed. Histological examination of sections showed massive hemorrhage, surrounded fibrous connective tissue, and numerous macrophages with hemosiderin deposits; these histological findings resembled cystic endometriosis. The clinicopathological features and pathogenesis of the pancreatic endometrial cyst are discussed. 相似文献
98.
Shimada H Yuzawa M Hirose T Nakashizuka H Hattori T Kazato Y 《Japanese journal of ophthalmology》2008,52(4):282-288
PURPOSE: To compare the pathological findings between multifocal choroiditis with panuveitis (MCP) and punctate inner choroidopathy (PIC). METHODS: Fourteen eyes of 14 patients clinically diagnosed as having MCP or PIC who underwent surgical excision of choroidal neovascularization (CNV) were studied. Immunohistochemical findings of the excised CNV in MCP (eight eyes) and PIC (six eyes) cases were compared. Antibodies against vascular endothelial growth factor (VEGF), CD68, CD3, and CD20 were used as primary antibodies. RESULTS: Expression of VEGF and CD68 in the CNV was observed in all MCF and PIC cases. In three of eight eyes with MCP, intraocular inflammatory findings were found clinically, while immunohistochemical study demonstrated infiltration of CD20-positive B lymphocytes in the CNV. No B lymphocyte infiltration was found in the six eyes with PIC. No differences in pathological findings were found between the five MCP eyes without intraocular inflammation and the six PIC eyes, with all eyes showing no B lymphocyte infiltration. CONCLUSIONS: In MPC cases showing clinical inflammatory findings, infiltration of B lymphocytes was also observed histopathologically, suggesting that the presence of inflammatory cells in the anterior chamber or vitreous body clinically is an indicator of active inflammatory CNV. However, this study clarifies that MCP eyes without intraocular inflammation and PIC eyes are not different in histopathological findings. 相似文献
99.
Toshinori Tsuruta Chunyan Yang Hiroshi Ueki Guangying Li Akiko Maekawa Hideki Kamikawa Eisaku Oku Takao Somehara Hiroshi Fujito Hideharu Tatebayashi Shigeto Yamada 《Nihon shinkei seishin yakurigaku zasshi》2007,27(1):9-12
A rapid and sensitive high-performance liquid chromatographic method was validated and described for determination of paroxetine in human saliva. Following liquid-liquid extraction of the drug and an internal standard (dibucaine), chromatographic separation was accomplished using a C18 analytical column with a mobile phase consisting of 0.05 mol/L sodium phosphate buffer, pH 5.0, and acetonitrile (A 30:70, v/v; B 60:40, v/v). Paroxetine and the internal standard were detected by ultraviolet absorbance at 205 nm. The average recoveries of the drug and internal standard were 92.5% and 89%, respectively. The lower limits of detection and quantification were 1 and 4 ng/ml, respectively, and the calibration curve was linear over a concentration range of 4 ng/ml. The saliva level of paroxetine in patients with depression taking 10 to 40 mg/day of the drug was significantly correlated with the plasma level of paroxetine in each patient (r = 0.617, P < 0.004, n = 19). These data indicate that the saliva level of paroxetine could be a useful marker to predict the plasma level of the drug. 相似文献
100.
Fukumoto A Kim YP Matsumoto A Takahashi Y Shiomi K Tomoda H Omura S 《The Journal of antibiotics》2008,61(1):1-6
Cyslabdan, a new potentiator of imipenem activity against methicillin-resistant Staphylococcus aureus, was isolated from the culture broth of Streptomyces sp. K04-0144 by Diaion HP-20 and ODS column chromatographies and preparative HPLC. The structure of cyslabdan was elucidated by spectroscopic analyses including NMR. The compound has a labdane-type diterpene skeleton connecting with an N-acetylcysteine via thioether linkage. 相似文献