全文获取类型
收费全文 | 15551篇 |
免费 | 718篇 |
国内免费 | 104篇 |
专业分类
耳鼻咽喉 | 121篇 |
儿科学 | 243篇 |
妇产科学 | 266篇 |
基础医学 | 1792篇 |
口腔科学 | 293篇 |
临床医学 | 1003篇 |
内科学 | 3978篇 |
皮肤病学 | 284篇 |
神经病学 | 818篇 |
特种医学 | 643篇 |
外科学 | 3357篇 |
综合类 | 74篇 |
一般理论 | 1篇 |
预防医学 | 483篇 |
眼科学 | 289篇 |
药学 | 780篇 |
中国医学 | 30篇 |
肿瘤学 | 1918篇 |
出版年
2023年 | 114篇 |
2022年 | 212篇 |
2021年 | 323篇 |
2020年 | 185篇 |
2019年 | 226篇 |
2018年 | 325篇 |
2017年 | 263篇 |
2016年 | 285篇 |
2015年 | 333篇 |
2014年 | 415篇 |
2013年 | 481篇 |
2012年 | 835篇 |
2011年 | 956篇 |
2010年 | 558篇 |
2009年 | 461篇 |
2008年 | 885篇 |
2007年 | 950篇 |
2006年 | 856篇 |
2005年 | 860篇 |
2004年 | 811篇 |
2003年 | 789篇 |
2002年 | 718篇 |
2001年 | 406篇 |
2000年 | 396篇 |
1999年 | 383篇 |
1998年 | 224篇 |
1997年 | 152篇 |
1996年 | 153篇 |
1995年 | 111篇 |
1994年 | 97篇 |
1993年 | 109篇 |
1992年 | 238篇 |
1991年 | 193篇 |
1990年 | 186篇 |
1989年 | 185篇 |
1988年 | 174篇 |
1987年 | 173篇 |
1986年 | 149篇 |
1985年 | 157篇 |
1984年 | 116篇 |
1983年 | 101篇 |
1982年 | 55篇 |
1979年 | 78篇 |
1978年 | 68篇 |
1977年 | 53篇 |
1975年 | 44篇 |
1974年 | 48篇 |
1973年 | 48篇 |
1971年 | 50篇 |
1968年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
Numerical aberrations of chromosome 9 in bladder cancer. A possible prognostic marker for early tumor recurrence 总被引:3,自引:0,他引:3
Tsukamoto M Matsuyama H Oba K Yoshihiro S Takahashi M Naito K 《Cancer Genetics and Cytogenetics》2002,132(1):41-45
Bilharzial bladder cancer is one of the most common types of malignancy in both men and women in several developing countries including Egypt. It has several unique clinical, epidemiological, and histological characteristics, suggesting that it is an entity distinct from bladder cancer seen in Western countries. Genetic alterations in bilharzial-related bladder cancer have been studied infrequently, especially in the advanced stages of disease, that is, T3 and T4 classifications. The objective of this study was to extend establishing the baseline cytogenetic profile of this type of malignancy to early T1 and T2 classifications. For this purpose, fluorescence in situ hybridization was applied to interphase nuclei of frozen-stored samples with biotinylated repetitive DNA probes specific for all chromosomes to detect numerical chromosome changes in 35 patients presenting with relatively early-stage pT1 and pT2 disease. Eleven cases had squamous cell carcinoma (SCC) and 24 had transitional cell carcinoma. Six of 24 transitional cell carcinomas had diploid chromosome counts with all the probes. Numerical chromosome aberrations were detected in 18 cases (75%). In 12 cases, a loss of chromosome 9 was observed. In three cases, an additional loss of chromosome 17 was detected. One case demonstrated a loss of chromosome 10, whereas another two cases showed a gain of chromosome 7, next to a loss of chromosome 9. Loss of chromosome Y was observed in nine of the 27 male cases studied (33.3%), in which only one case showed an abnormality whereas four cases were detected next to loss of chromosome 9, and one case showed gain of chromosome 7. Five cases showed loss of chromosome 19 whereas gain of chromosome 4 was detected in two cases. Two of 11 samples of SCC had normal diploid chromosome counts with all the probes used. In four of 11 cases (36.4%) underrepresentation of chromosome 9, compared with the other chromosomes, was detected. An additional loss of chromosome 17 and gain of chromosome 7, next to loss of chromosome 9, was detected in three cases. One case showed loss of chromosome 17 as the only numerical aberration. Loss of the Y chromosome was detected in three cases of which one case had gain of chromosome 7 and one case had loss of chromosome 19. No correlation was found between any of the clinicopathologic parameters examined in this study and the presence or absence of any numerical chromosomal aberrations except for the significant association between schistosomal history and loss of Y chromosome (P=0.007). 相似文献
73.
Roles of the Maltese cross form in the development of parasitemia and protection against Babesia microti infection in mice
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yokoyama N Bork S Nishisaka M Hirata H Matsuo T Inoue N Xuan X Suzuki H Sugimoto C Igarashi I 《Infection and immunity》2003,71(1):411-417
Babesia microti, a hemoprotozoan parasite of rodents, is also important as a zoonotic agent of human babesiosis. The Maltese cross form, which consists of four masses in an erythrocyte, is characteristic of the developmental stage of B. microti. Monoclonal antibody (MAb) 2-1E, which specifically recognizes the Maltese cross form of B. microti, has been described previously. In the present study, we examined the roles of the Maltese cross form during the infectious course of B. microti in mice. The number of the Maltese cross form increased in the peripheral blood of infected mice prior to the peak of parasitemia. With confocal laser scanning microscopy, MAb 2-1E was found to be reactive with the ring form, with the parasites undergoing transformation to the Maltese cross form and subsequent division, and also with extracellular merozoites. Furthermore, the Maltese cross form-related antigen (MRA) gene was isolated from a B. microti cDNA library by immunoscreening with MAb 2-1E, and the nucleotide sequence was determined. Genomic analyses indicated that the MRA gene exists as a single-copy gene in B. microti. Immunization of mice with recombinant MRA induced significant protective immunity against B. microti infection. These findings indicate that the Maltese cross form plays important roles in both the development of parasitemia and the protective response against the infection. 相似文献
74.
Sotos syndrome and haploinsufficiency of NSD1: clinical features of intragenic mutations and submicroscopic deletions 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Journal of medical genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
75.
Masai T Taniguchi K Kuki S Yokota T Yoshida K Yamamoto K Matsuda H 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2003,49(1):108-111
Although gastric mucosal tonometry has been reported as a useful method to assess splanchnic perfusion during cardiovascular surgery, the conventional discontinuous method of tonometry (saline tonometry) was cumbersome and prone to systematic errors. A new automated system of air tonometry (Tonocap; Datex Ohmeda, Helsinki, Finland) allows for frequent (every 10 minutes) measurement of gastric regional CO2 (PrCO2) and may be more suitable as a monitoring system in cardiac patients. We evaluated the usefulness of continuous air tonometry as a marker of splanchnic perfusion during cardiopulmonary bypass (CPB). In 19 patients (53-79 years, mean 63 years) who underwent cardiovascular surgery under standard CPB with mild hypothermia (32 degrees C) from January 2001 to May 2002, the PrCO2 and calculated intramucosal pH (pHi) of gastric tonometry was monitored using Tonocap, and their relation to postoperative visceral organ function was evaluated. The pHi significantly increased after initiation of CPB from 7.32 +/- 0.07 to 7.43 +/- 0.10 (p < 0.05) and then consistently decreased in all patients to 7.39 +/- 0.09 at the end of CPB. The value of PrCO2 significantly (p < 0.01) correlated with the value of pHi. The lowest value of pHi during CPB was significantly related to blood urea nitrogen (r = -0.75, p < 0.05), serum creatinine (r = -0.78, p < 0.05), creatinine clearance (r = 0.68, p < 0.05) on postoperative day 1, and blood urea nitrogen (r = -0.84, p < 0.01) on day 3. In contrast, arterial blood lactate level, venous oxygen saturation, and routinely measured hemodynamics (e.g., pump flow, arterial pressure) during CPB were unrelated to the postoperative visceral organ function. These results suggest that continuous monitoring of gastric regional CO2 and pHi by air tonometry system is useful for the evaluation of splanchnic perfusion during CPB and may contribute to improve CPB technique by allowing the early detection of visceral malperfusion. 相似文献
76.
Hiroto Yamashita Shiro Noguchi Iwao Nakayama Hiroshi Togon Akira Moriuchi Shigeo Yokoyama Yuichi Mochizuki Akito Noguchi 《Pathology international》1984,34(1):123-132
A case of nonfunctioning parathyroid carcinoma in a 69-year-old female has been studied by light and electron microscopy. The tumor, located on the left side of the anterior neck, was well encapsulated by connective tissue but showed invasion to the capsule and to the thyroid. The tumor cells exhibited a trabecular arrangement surrounded by capillary networks but focally showed several ductal structures. They were polygonal in shape, had a large nucleus showing frequent mitosis and poor cytoplasm containing glycogen. Some tumor cells had clear and abundant cytoplasm, and resembled water-clear cells of the parathyroid. Immunohistochemically, no thyroglobulin was demonstrated in the tumor tissue. Electronmicroscopically, the tumor cells with high N/C ratio contained poorly developed cell organelles and abundant glycogen particles. They were poor in secretory granules and had no conglomeration of lipid. Desmosomes and tonoflbrils were observed. The ratio of the reported number of nonfunctioning parathyroid carcinoma to that of functioning one in Japan was compared with that in western countries. No difference of the ratio was found between these two, when identical criteria were employed. 相似文献
77.
Biomimetic porous scaffolds with high elasticity made from mineralized collagen--an animal study 总被引:1,自引:0,他引:1
Yokoyama A Gelinsky M Kawasaki T Kohgo T König U Pompe W Watari F 《Journal of biomedical materials research. Part B, Applied biomaterials》2005,75(2):464-472
Histological investigations of a new hydroxyapatite-collagen composite material were carried out to evaluate its possible suitability as a bone substitute. The three-dimensional scaffolds made from biomimetically mineralized collagen exhibit an interconnecting pore structure and elastic mechanical properties. They were implanted into the subcutaneous tissue and bone defects made in the femur of rats and harvested with the surrounding tissue at 1, 2, 4, 8, and 12 weeks after surgery. The materials implanted in the subcutaneous tissue were covered by fibrous connective tissue with a slight inflammatory response, and many foreign-body giant cells were observed on the surface of the scaffolds. Most of the material implanted in the subcutaneous tissue was resorbed at 8 weeks by phagocytosis. In the bone defects, new bone formation was observed on the surface of the material at 1 week. New bone increased with time, and osteoclasts were seen on the surface of the scaffolds at 2 weeks. Resorption and replacement by new bone of many parts of the materials implanted in the femur were observed by 12 weeks. These responses occurred faster than those of other hydroxyapatite-collagen composites. The results suggested that the new biomimetically mineralized collagen scaffolds were suitable as an implant material for bone-tissue reconstruction. 相似文献
78.
Massive apoptosis in infantile myofibromatosis. A putative mechanism of tumor regression. 总被引:4,自引:3,他引:4
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Y. Fukasawa H. Ishikura A. Takada S. Yokoyama M. Imamura T. Yoshiki H. Sato 《The American journal of pathology》1994,144(3):480-485
Two cases of solitary infantile myofibromatosis (IM) are presented. Solitary IM are tumors prone to spontaneous regression. Histopathologically, several tumor lobules in our IM cases had central areas of massive cell death, with nuclear pyknosis, cytoplasmic hyalinization and nuclear fragmentation but without lymphoid or neutrophilic cell infiltration. These central cell death areas consisted of about 40% in case 2 and 50% in case 1 of the entire tumor tissues, respectively. Electron microscopy revealed that the condensed nuclei and cytoplasm were fragmented into "apoptotic bodies", with or without phagocytosis by histiocytes. DNA fragmentation, as evidenced by the terminal deoxy transferase-mediated uptake of biotinylated dUTP, was identified at massive cell death areas on paraffin sections from both cases. A characteristic 180- to 190-bp nucleosomal ladder was detected in DNA obtained from the tumor cells in case 1. The collective evidence suggested that these tumors underwent a central, massive apoptosis. As massive cell death similar to that seen in the present cases has been described in other documented cases of IM, we propose that the spontaneous regression that frequently occurs with this type of tumor may be mediated by massive apoptotic cell death. 相似文献
79.
Haruyuki Hirata Naoaki Yokoyama Xuenan Xuan Kozo Fujisaki Naoyoshi Suzuki Ikuo Igarashi 《Clinical and Vaccine Immunology : CVI》2005,12(2):334-338
In this study, we characterized a Babesia equi Be158 gene obtained by immunoscreening a B. equi cDNA expression phage library with B. equi-infected horse serum. The Be158 gene consists of an open reading frame of 3,510 nucleotides. The recombinant Be158 gene product was produced in Escherichia coli and used for the immunization of mice. In Western blot analysis, mouse immune serum against the Be158 gene product recognized 75- and 158-kDa proteins from the lysate of B. equi-infected erythrocytes. In an indirect fluorescent-antibody test with the mouse immune serum, the Be158 antigen appeared in the cytoplasm of Maltese cross-forming parasites (which consist of four merozoites) and was located mainly in the extraerythrocytic merozoite body. When the recombinant Be158 gene product was used in an enzyme-linked immunosorbent assay as a serological antigen, it was found to react to B. equi-infected horse sera, indicating that the Be158 gene product is useful as a serologically diagnostic antigen for B. equi infection. 相似文献
80.
Campylobacter jejuni isolation is the standard for the diagnosis of this type of bacterial infection, but there have been no epidemiological studies of a large number of C. jejuni isolates from patients with Guillain-Barre syndrome (GBS) and Fisher syndrome (FS). For 13 years, stool specimens from GBS/FS patients have been sent from 378 hospitals throughout Japan to the Tokyo Metropolitan Institute of Public Health. A total of 113 strains (11%) were isolated from the stool specimens from 1,049 patients. The isolation rate did not differ by region. The rates were 22% for 449 patients with a history of diarrhea and 2% for the others. An additional 18 isolates were provided by various hospitals. There was no noticeable seasonal distribution in the onset of C. jejuni isolated from patients with GBS/FS. The male/female ratios were 1.7:1 for GBS and 2.2:1 for FS. The patient age range showed a peak in 10- to 30-year-old subjects who had GBS and in 10- to 20-year-old subjects who had FS. The predominance of young adults and male patients who had C. jejuni-associated GBS/FS may be related to the preponderance of young adults and male patients who had C. jejuni enteritis. The median interval from diarrhea onset to neurologic symptom onset was 10 days for GBS/FS. Penner's C. jejuni serotype HS:19 was more frequently present in GBS (67%) than in enteritis (6%) patients. HS:2 was more frequent in FS (41%) than in enteritis (14%) patients. These findings suggest that certain C. jejuni strains specifically trigger GBS and that others specifically trigger FS. 相似文献