全文获取类型
收费全文 | 68765篇 |
免费 | 5218篇 |
国内免费 | 1947篇 |
专业分类
耳鼻咽喉 | 896篇 |
儿科学 | 1290篇 |
妇产科学 | 2239篇 |
基础医学 | 8381篇 |
口腔科学 | 1236篇 |
临床医学 | 7368篇 |
内科学 | 12415篇 |
皮肤病学 | 1253篇 |
神经病学 | 4146篇 |
特种医学 | 2776篇 |
外国民族医学 | 6篇 |
外科学 | 8896篇 |
综合类 | 5469篇 |
现状与发展 | 8篇 |
一般理论 | 11篇 |
预防医学 | 4123篇 |
眼科学 | 1548篇 |
药学 | 5887篇 |
24篇 | |
中国医学 | 2063篇 |
肿瘤学 | 5895篇 |
出版年
2024年 | 109篇 |
2023年 | 568篇 |
2022年 | 1447篇 |
2021年 | 2390篇 |
2020年 | 1479篇 |
2019年 | 1718篇 |
2018年 | 2089篇 |
2017年 | 1659篇 |
2016年 | 1652篇 |
2015年 | 2535篇 |
2014年 | 3144篇 |
2013年 | 3706篇 |
2012年 | 5224篇 |
2011年 | 5136篇 |
2010年 | 3414篇 |
2009年 | 2962篇 |
2008年 | 3948篇 |
2007年 | 3954篇 |
2006年 | 3686篇 |
2005年 | 3346篇 |
2004年 | 2994篇 |
2003年 | 2854篇 |
2002年 | 2443篇 |
2001年 | 1918篇 |
2000年 | 1686篇 |
1999年 | 1359篇 |
1998年 | 578篇 |
1997年 | 480篇 |
1996年 | 440篇 |
1995年 | 391篇 |
1994年 | 357篇 |
1993年 | 254篇 |
1992年 | 721篇 |
1991年 | 589篇 |
1990年 | 534篇 |
1989年 | 495篇 |
1988年 | 435篇 |
1987年 | 433篇 |
1986年 | 364篇 |
1985年 | 302篇 |
1984年 | 233篇 |
1983年 | 196篇 |
1982年 | 120篇 |
1981年 | 130篇 |
1980年 | 103篇 |
1979年 | 209篇 |
1978年 | 164篇 |
1977年 | 103篇 |
1976年 | 113篇 |
1975年 | 107篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Alex Y. Chang Z. Nora Tu Julia L. Smith Philip Bonomi Thomas J. Smith Peter H. Wiernik Ronald Blum 《Investigational new drugs》1995,13(2):137-141
Summary Fifty-five patients with metastatic non-small cell lung cancer (NSCLC) were entered into this phase II randomized study for evaluating three new agents: gallium nitrate, amonafide and teniposide. The patients had to have ECOG performance status 0 or 1, no prior chemotherapy, and adequate hematological, hepatic and renal functions. Forty-seven patients were eligible and evaluable. Fourteen were randomized to receive gallium nitrate, 18 to amonafide and 15 to teniposide. Seventy-four percent of eligible patients were male. The majority of patients (89%) had an ECOG performance status 1. ECOG grade 4 toxicity occurred twice in patients on gallium nitrate, seven times on amonafide and 18 times on teniposide. The cause of death was attributed to amonafide in one patient (from sepsis) and to teniposide in two patients (due to infection and leukopenia). There was no objective response in all the patients entered. The overall survival times ranged from 2 weeks to 156 weeks with a median of 23 weeks. There were no survival differences among the three treatment arms. We conclude that gallium nitrate, amonafide and teniposide are inactive in metastatic NSCLC and do not warrant any further testing in this disease.The contents of this study is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute. 相似文献
43.
Using the polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis, we have examined the highly conserved regions of the p53 gene in 58 biopsy samples of head and neck tumors. Mutations were found in 13/58 (23%) tumor specimens, but not in 6 normal tissues. Ten of 13 mutations were due to single base changes and the remaining 3 were 1- or 8-base deletion mutants. These mutations were clustered in exons 5 and 7 and resulted in amino acid changes. Our results seem to indicate that mutations in the p53 gene contribute to a significant number of cases of the head and neck tumors including 20% of nasopharyngeal carcinoma biopsies. The relationship of Epstein-Barr virus or human papillomavirus and p53 gene mutations in this group of cancers was also analyzed and discussed. 相似文献
44.
Ca-mediated stimulation of Cl secretion by reactive oxygen metabolites in human colonic T84 cells. 下载免费PDF全文
H Tamai T S Gaginella J F Kachur M W Musch E B Chang 《The Journal of clinical investigation》1992,89(1):301-307
Monochloramine (NH2Cl), a granulocyte-derived reactive oxygen metabolite (ROM), increases short-circuit current (Isc) in cultured T84 monolayers in a concentration-dependent manner up to nonlethal concentrations of 75 microM. Isc increases slowly after NH2Cl, reaching a peak value of 18 +/- 2 microA/cm2 20 min after addition. The Isc changes are persistent (lasting over 20-30 min), depend on medium Cl, and are inhibitable with bumetanide. 36Cl flux studies demonstrated that NH2Cl increases serosa-to-mucosa flux of Cl without changing mucosa-to-serosa flux, consistent with stimulation of electrogenic Cl secretion. Isc responses to NH2Cl, but not PGE2, are dependent on medium calcium. As demonstrated in fura-2-loaded T84 cells, NH2Cl increases free cytosolic calcium by influx of extracellular Ca2+ and by release of Ca2+ from endogenous stores. However, NH2Cl had no effect on phosphatidylinositol metabolism or cyclic nucleotide levels. We conclude that ROM directly stimulate electrolyte secretion, an effect in part mediated by increases in cytosolic Ca2+, possibly through increasing Ca2+ permeability of cellular membranes. 相似文献
45.
46.
A W Chiu M T Chen W J Huang S T Young C Cheng S W Huang C L Chu L S Chang 《European urology》1992,22(3):250-254
Laparoscopic nephrectomy was performed in 15 male pigs, the procedure was successful in 14. Extraction of the intact kidney through a 5-cm lower abdomen incision was done in 7 animals; complete destruction and evacuation of the kidney was accomplished by a round-knife suction device through a 1-cm port in another 7 pigs. Grossly, the specimen consisted of sausage-like tubular renal tissue and a small amount of tissue debris. Pathology revealed that the glomerular and tubular structures were well preserved, no interstitial hematoma could be found. Four ports were usually used, one 1-cm umbilical camera port, one 0.5-cm port for ureter traction, and two 1-cm working ports along the midclavicular line. All the pigs recovered uneventfully. The average operation time was 3 h 20 min. The application of endo-GIA (United States Surgical Corporation) for renal hilum reduced the operative time to 2 h 20 min. Complications included renal vein tear during endoclip application and cutting in the first case, mild subcutaneous emphysema in 2 cases. This first pig received exploratory laparotomy for the repair and ligation of the renal vein. No more major complications occurred with increasing experience. From this porcine experiment, we conclude that the combination of laparoscopy, a tissue destroyer and an endobag for the entrapment of kidney seem to be a promising technique for clinical nephrectomy. 相似文献
47.
目的研究采用自体静脉管套入吻合口并注入脑细胞生长肽的方法,对面神经损伤后功能恢复的影响.方法吻合神经断端后用自体静脉管套入吻合口并注入脑细胞生长肽.分析肌电图和观察表情肌功能恢复,比较两种方法对损伤的面神经功能恢复的影响.结果自体静脉管套入吻合口并注入脑细胞生长肽的方法,比传统方法表情肌功能恢复时间明显缩短,且一期修复比二期修复功能恢复时间明显缩短,差异具有非常显著性意义(P<0.01).两种方法修复面神经损伤,表情肌功能恢复后检测面神经传导速度差异无显著性意义(P>0.05).结论自体静脉管套入吻合口并注入脑细胞生长肽的方法是一种比较有前途的面神经修复方法. 相似文献
48.
P Y Chang K C Lin C Y Chuang C R Wang M Y Chen W C Hsieh G R Wang D L Cheng K S Chang Y C Ko 《Asian Pacific journal of allergy and immunology / launched by the Allergy and Immunology Society of Thailand》1992,10(1):65-68
From May 1, 1985 to December 31, 1991, a total of 4,962,707 serum samples from 8 population groups in Taiwan were tested for anti-human immunodeficiency virus type 1 (anti-HIV-1). In total, 256 samples were seropositive; of these individuals, 43 developed acquired immunodeficiency syndrome (AIDS): 29 were homosexuals; 5 were hemophiliacs; 8 were heterosexuals and 1 was of unknown risk. Although the prevalence of HIV-1 infection and AIDS remains low compared with other countries, since 1988 the increase has been rapid. Before 1977 the majority were homosexuals and hemophiliacs; thereafter the risk groups diversified, with a trend away from homosexuals and hemophiliacs towards heterosexuals and intravenous drug abusers (IVDAs). A few patients have caused serious social problems for the public, health care workers and families. Active community efforts are needed to achieve future success in the control of HIV-1 infection and AIDS in Taiwan. 相似文献
49.
The in vitro DNA amplification technique of polymerase chain reaction was used to evaluate the possible presence of human papillomavirus (HPV) in small cell carcinoma of the uterine cervix. None of the 12 cases examined contain detectable amounts of either HPV type 16, 18, 31, or 33 DNA. On the other hand, HPV types 16 and 18 DNA were found in 14 (93.3%) and 9 (60.0%) of 25 invasive cervical squamous carcinoma tissues. The results seem to suggest that these types of HPV are not present or are present in extremely small quantities in cervical small cell carcinoma. Such an absence of HPV DNA makes it unlikely that these types of HPV play any etiological role in the pathogenesis of cervical small cell carcinoma. 相似文献
50.
Julia Yu-Fong Chang Jeng-Tzung Wang Yi-Ping Wang Bu-Yuan Liu Andy Sun Chun-Pin Chiang 《台湾医志》2003,102(12):876-882
BACKGROUND AND PURPOSE: Odontoma is the most common odontogenic tumor. It includes 2 types, the compound and complex odontomas. There has not been a series study of the clinical and histologic features of odontomas from Taiwan. This study evaluated the clinicopathologic features of odontoma in Taiwanese. METHODS: Cases of odontoma treated from 1998 to 2002 identified from medical records were included. The microscopic features, radiographic features, and clinical history of the patients were reviewed and analyzed. RESULTS: A total of 81 odontomas in 81 patients (36 males and 45 females) were included. There were 62 compound and 19 complex odontomas. The mean age of the patients was 18 years with the majority of odontomas occurring in the first (32%) and second decade (38%) of life. Odontomas had a marked predilection for the maxilla (70%) and for the anterior region of the jaw (83%), particularly for the anterior maxilla (62%). Sixty four (79%) of the 81 odontomas were associated with 80 impacted teeth, including 71 permanent teeth, 2 deciduous teeth, and 7 supernumerary teeth. Of the 71 impacted permanent teeth, the maxillary central incisor (27%) was most commonly affected, followed by the maxillary canine (26%) and mandibular canine (24%). Histologic examination revealed enamel matrix in 90%, dentin in 100%, cementum in 88%, pulp tissue in 96%, fibrous capsule in 93%, ghost cells in 83%, reduced enamel epithelium in 86%, and nests of odontogenic epithelium in 58% of odontomas. Dentigerous cyst was associated with 9% of odontomas. CONCLUSIONS: In this series, odontomas occurred most often in the first and second decade of life. Although complex odontomas are usually found in the posterior jaw, in this Taiwanese series they were most commonly found in the anterior maxilla. Odontoma is frequently associated with an impacted tooth and occasionally with a dentigerous cyst. No recurrence of odontomas was found after surgical excision with follow-up of 1 to 15 years. 相似文献