首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3334篇
  免费   150篇
  国内免费   23篇
耳鼻咽喉   20篇
儿科学   48篇
妇产科学   35篇
基础医学   374篇
口腔科学   136篇
临床医学   170篇
内科学   1124篇
皮肤病学   17篇
神经病学   214篇
特种医学   181篇
外科学   415篇
综合类   9篇
预防医学   99篇
眼科学   148篇
药学   202篇
中国医学   1篇
肿瘤学   314篇
  2023年   23篇
  2022年   36篇
  2021年   79篇
  2020年   39篇
  2019年   47篇
  2018年   63篇
  2017年   49篇
  2016年   57篇
  2015年   70篇
  2014年   100篇
  2013年   114篇
  2012年   200篇
  2011年   197篇
  2010年   111篇
  2009年   97篇
  2008年   176篇
  2007年   194篇
  2006年   183篇
  2005年   184篇
  2004年   173篇
  2003年   128篇
  2002年   148篇
  2001年   74篇
  2000年   66篇
  1999年   73篇
  1998年   50篇
  1997年   33篇
  1996年   42篇
  1995年   33篇
  1994年   38篇
  1993年   31篇
  1992年   68篇
  1991年   50篇
  1990年   42篇
  1989年   48篇
  1988年   38篇
  1987年   52篇
  1986年   42篇
  1985年   48篇
  1984年   41篇
  1983年   21篇
  1982年   16篇
  1981年   28篇
  1980年   16篇
  1979年   17篇
  1978年   14篇
  1977年   12篇
  1976年   8篇
  1975年   8篇
  1968年   4篇
排序方式: 共有3507条查询结果,搜索用时 203 毫秒
41.
Three common branches of the celiac trunk are the left gastric artery, the splenic artery and the common hepatic artery. The variation of the three branches of the celiac trunk has an importance for the arterial supply to the digestive organs of the upper abdomen. In this study, we present three cases of the gastrosplenic and the hepatomesenteric trunks in Japanese cadavers. Especially, in Case 1, the left inferior phrenic artery arose from the gastrosplenic trunk and the left hepatic artery arose from the left gastric artery. In Cases 2 and 3, the common hepatic artery penetrated the pancreatic parenchyma before reaching liver. In Case 3, the right hepatic artery arose from the hepatomesenteric trunk.  相似文献   
42.
To assess muscle metabolism and inorganic phosphate (Pi) peak splitting during exercise, 31-phosphorus nuclear magnetic resonance spectroscopy was performed during ramp incremental and submaximal step exercise with and without circulatory occlusion. Seven healthy men performed calf flexion in a superconducting magnet. There was no Pi splitting during ramp incremental exercise with the circulation present and phosphocreatine (PCr) decreased linearly by 0.07 (SEM 0.01) mmol?·?l?1?·?s?1, while exercise with the circulation occluded caused the Pi peak to split into a high and a low pH peak. The rate of PCr decrease during exercise with the circulation occluded was 0.15 (SEM 0.03) mmol?·?l?1?·?s?1 which with the efficiency of the adenosine 5′-triphosphate (ATP) hydrolysis reaction corresponded well to the mechanical energy. Both with and without occlusion of the circulation PCr decreased with some time lag which may reflect the consumption of residual oxygen. In submaximal step exercise PCr decreased exponentially at the onset of exercise with the circulation open whereas it decreased linearly by 0.15?mmol?·?l?1?·?s?1 when the circulation was occluded. After exercise, occlusion of the circulation was maintained for 1 min more and there was no PCr resynthesis. It is suggested that ATP synthesis was limited by the availability of oxygen.  相似文献   
43.
A simple system has been developed-for the prolonged infusion of an iced solution of prostacyclin (PGI2). In a 24 h period at pH 10, there is a theoretical loss in activity of 6%, while a 5 h infusion leads to a 2% reduction in activity. The stability of the cooling system was demonstrated in six dog experiments where mean arterial pressure (MAP) was reduced to 58±3.8 Torr (x±SEM) over a 5 h period of infusing 500 ng/kg/min. In a saline medium, at 3°C, a 5 h PGI2 infusion led to a stable reduction in MAP, whereas, at a temperature of 24°C, a 70 loss of infusate activity was noted. Supported in part by The National Institute of Health, Grant No. GM24891-04; The U.S. Army Medical Research and Development Command, Contract No. DAMD17-78-C-8026; The Brigham Surgical Group, Inc., and The Trauma Research Foundation.  相似文献   
44.
We found 12 patients with congenital heart disease of unknown etiology complicated with blepharoptosis during a period from Sept. 1, 1981 to April 30, 1989. All the patients with congenital heart disease were acyanotic, including 10 with short stature. Among these 10, abnormalities of high frequency were intrauterine growth retardation (5 cases), mental retardation (5), microcephaly (3), epicanthus (4), high arched palate (4), sacral dimple (4), and distal axial triradius (3). It is postulated that the association of congenital heart disease, blepharoptosis and short stature might indicate pathogenetic relationships.  相似文献   
45.
In patients with inflammatory conditions such as infection, cytokines induce the production of C-reactive protein(CRP) and serum amyloid A protein(SAA) in hepatic cells. It has been reported that upon viral infection, the serum SAA level increases by a greater degree than the serum CRP level. Procalcitonin (PCT), the precursor of calcitonin, is a new type of inflammatory marker that is specifically induced by bacterial infection, sepsis and lethal multiple organ failure, but not by viral infection, autoimmune diseases, tumors or surgical stress. To evaluate the immunoluminometric assay(LUMI test PCT; Brahms Diagnostics, Berlin, Germany) procedure for determining the PCT level and to study the clinical significance of the serum PCT level, we determined the serum levels of PCT, CRP and SAA in patients with various inflammatory diseases and normal subjects. The serum PCT level in the normal subjects was < 0.3 ng/ml. Among the patients with inflammatory disease who had a high CRP level(CRP > 20000 micrograms/dl), the PCT level was elevated only in those patients with severe bacterial infection. These results suggest that determining the PCT level may be useful in the differential diagnosis of severe bacterial infection. The patients who had a low CRP level(CRP < 150 micrograms/dl), had a PCT level within the normal range. The patients with autoimmune disease, viral infection, and fungal infection did not have an elevated PCT level.  相似文献   
46.
GB virus C (GBV-C) is related to hepatitis C virus (HCV) and has a similar genomic structure. Some predictors for the efficacy of interferon (IFN) therapy on HCV have been reported: genotype, viral load, IFN dose, and the amino acid substitutions in the NS5A region, designated as the interferon sensitivity determining region (ISDR). To evaluate the correlation between the amino acid substitutions in the GBV-C NS5A region and the response to IFN therapy, single-strand conformation polymorphism (SSCP) analysis was performed in the 12 concomitantly GBV-C-and HCV-infected patients who received IFN therapy at three time points: before, end-point, and after the IFN therapy. The region in the GBV-C NS5A studied includes the amino acids that exhibit some homology to the ISDR and the various substitutions. By SSCP analysis, amplicons were separated into 1-4 bands, which indicated the existence of heterogeneity in each host. However, the deduced amino acid sequences in these bands exhibited no characteristic differences among these strains irrespective of response to IFN therapy. Of the 32 strains separated by SSCP, 7 strains were responders, and 25 were nonresponders. The mean amino acid substitution, compared with the consensus sequence of nonresponders, was 1.00+/-0.93 among responders, and 1.40+/-0.85 among non-responders (P= NS). No correlation between the amino acid sequence in the GBV-C NS5A region and response to IFN therapy was found, indicating that the GBV-C NS5A region dose not act as the ISDR.  相似文献   
47.
Ohba  M.  Aizawa  K. 《Archives of virology》1981,68(2):153-156
Summary Intraperitoneal injection of large doses of the two arthropod iridoviruses,Armadillidium iridescent virus (AvIV) andChilo iridescent virus, was lethal to the frog,Rana limnocharis. The LD50 of purified AvIV for the frog was 2.7 µg. While UV-inactivated AvIV produced a lethal toxicity to the frog, heat-inactivated AvIV did not show any toxicity. Lethal toxicity of AvIV was neutralized by the homologous rabbit antiserum but not by the heterologous antisera.  相似文献   
48.
Flagellar (H) antigens of 189 acrystalliferous spore-forming bacteria, referable to Bacillus cereus, isolated from soils and silkworm litters of Japan, were analyzed by using H antisera against Bacillus thuringiensis H serotypes 1–20. These isolates proved to share common H antigens at a very high frequency of 29.6% (56/189) with the known 16 H serotypes of B. thuringiensis. This indicates that, in natural environments, B. cereus possessing B. thuringiensis H antigens is distributed more widely than crystalliferous B. thuringiensis.  相似文献   
49.
Recent studies have focused on whether different hepatitis C virus (HCV) genotypes are associated with different profiles of pathogenicity, infectivity, and response to antiviral therapy. The establishment of a simple and precise genotyping system for HCV is essential to address these issues. A new genotyping system based on PCR of the core region with genotype-specific PCR primers for the determination of HCV genotypes 1a, 1b, 2a, 2b, 3a, 3b, 4, 5a, and 6a was developed. A total of 607 samples (379 from Japan, 63 from the United States, 53 from Korea, 35 from Taiwan, 32 from China, 20 from Hong Kong, 15 from Australia, 6 from Egypt, 3 from Bangladesh, and 1 from South Africa) were tested by both the assay of Okamoto et al. (H. Okamoto, Y. Sugiyama, S. Okada, K. Kurai, Y. Akahane, Y. Sugai, T. Tanaka, K. Sato, F. Tsuda, Y. Miyamura, and M. Mayumi, J. Gen. Virol. 73:673-679, 1992) and this new genotyping system. Comparison of the results showed concordant results for 539 samples (88.8%). Of the 68 samples with discordant results, the nucleotide sequences of the HCV isolates were determined in 23, and their genotypes were determined by molecular evolutionary analysis. In all 23 samples, the assignment of genotype by our new genotyping system was correct. This genotyping system may be useful for large-scale determination of HCV genotypes in clinical studies.  相似文献   
50.
A 65-year-old man was admitted for dysuria. He had been irradiated 60Co for malignant lymphoma of tonsils 2 years earlier. The findings of palpation of prostate, retrograde urethrogram and urethroscopy strongly suggested benign prostatic hypertrophy. Retropubic prostatectomy was performed and 18 g of "adenoma" was resected. By histological observation, the "adenoma" proved to be malignant lymphoma. This tumor belonged to follicular lymphoma, medium-sized cell type of LSG non-Hodgkin's lymphoma classification. After the operation, he left our hospital for a personal reason and received systemic chemotherapy at another hospital.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号