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   1350篇
  免费   68篇
  国内免费   3篇
耳鼻咽喉   13篇
儿科学   25篇
妇产科学   101篇
基础医学   149篇
口腔科学   25篇
临床医学   81篇
内科学   302篇
皮肤病学   21篇
神经病学   64篇
特种医学   88篇
外科学   261篇
综合类   2篇
预防医学   35篇
眼科学   21篇
药学   82篇
中国医学   17篇
肿瘤学   134篇
  2022年   8篇
  2021年   29篇
  2020年   18篇
  2019年   23篇
  2018年   18篇
  2017年   11篇
  2016年   18篇
  2015年   23篇
  2014年   26篇
  2013年   30篇
  2012年   59篇
  2011年   74篇
  2010年   37篇
  2009年   34篇
  2008年   57篇
  2007年   53篇
  2006年   49篇
  2005年   62篇
  2004年   50篇
  2003年   49篇
  2002年   70篇
  2001年   41篇
  2000年   49篇
  1999年   39篇
  1998年   25篇
  1997年   17篇
  1996年   9篇
  1995年   13篇
  1994年   11篇
  1992年   42篇
  1991年   34篇
  1990年   36篇
  1989年   38篇
  1988年   26篇
  1987年   28篇
  1986年   25篇
  1985年   33篇
  1984年   21篇
  1983年   16篇
  1982年   6篇
  1979年   20篇
  1978年   5篇
  1977年   5篇
  1976年   8篇
  1974年   8篇
  1972年   8篇
  1971年   8篇
  1969年   12篇
  1968年   5篇
  1965年   4篇
排序方式: 共有1421条查询结果,搜索用时 31 毫秒
21.
A common amplification target encompassing chromosome region 3q25 to q27 has been identified by comparative genomic hybridization analyses in tumors of the cervix, ovary, endometrium, lung, and head and neck. Because this segment spans at least 30 megabases, we undertook a molecular analysis of copy number to more precisely define the amplification domain. Our Southern blot and fluorescence in situ hybridization results with the use of 17 markers confirmed the presence of low-level 3q amplification events in cervical, ovarian, and variant SCLC tumors. Most of the tumor types studied appeared to have similar, broad amplification domains centered within 3q26.2, suggesting that the same target is being affected in all. The ovarian carcinoma cell line NIH:OVCAR3 had a highly restricted amplification domain spanned by four overlapping YAC clones, suggesting a small target. The region of highest amplification included the gene for the RNA component of telomerase (hTR), supporting it as a potential target. Although the importance of low-level amplification is unknown, the consistent and reproducible nature of this event in a variety of carcinomas suggests that 3q26.2 harbors an oncogene whose low-level amplification has a significant influence on tumor biology.  相似文献   
22.
The altered patterns of transfer RNA in SV40-infected and transformed cells   总被引:4,自引:0,他引:4  
T Sekiya  K I Oda 《Virology》1972,47(1):168-180
  相似文献   
23.
Computed Tomography (CT) provides a noninvasive information in the evaluation of abnormalities of the gastrointestinal tract by direct imaging of the bowel wall and adjacent mesentery. Several prior studies have discussed the variable CT appearances of mesenteric abnormalities, such as lymphoma, metastasis, inflammatory disease and edema. Although mesenteric thickening was mentioned in these studies, no study has provided a detailed analysis of the CT appearance of the thickened mesentery. Two characteristic types of mesenteric thickening were identified in 47 patients. Type I is "Intra-mesenteric thickening", which was noted in 25 patients with vascular obstruction, inflammatory disease and edema. Type II is "Mesenteric surface thickening", which was noted in 22 patients with peritonitis carcinomatosa, peritoneal mesothelioma, tuberculous peritonitis and pseudomyxoma peritoneal. An understanding of these two types of mesenteric disease is important in the identification of mesenteric pathology.  相似文献   
24.
Recombinant human epidermal growth factor (rhEGF), a polypeptide of 53 amino acid residues, is subject to degradation by numerous enzymes, especially proteases, when it is applied on the skin for the treatment of open wound. Amastatin, aprotinin, bestatin, EDTA, EGTA, gabexate, gentamicin, leupeptin, and TPCK were investigated for the possible protease inhibitors, which may use to protect rhEGF from degradation by the enzymes in the skin. Skin homogenates containing protease inhibitors and rhEGF were incubated at 37°C for 30 minutes. After the reaction was stopped with trifluoroacetic acid, the amount of rhEGF remaining in the sample was determined with an HPLC method. The percentages of rhEGF degraded, at the skin/PBS ratio of 0.25, in the mouse, rat, and human skin homogenate were 85%, 70%, and 46%, respectively. The degree of degradation of rhEGF in the cytosolic fraction was higher than that in the membrane fraction and these enzyme reactions were completed in 30 minutes. Bestatin, EGTA, and TPCK showed significant inhibitory effects on the degradation of rhEGF in the two fractions (p<0.05), while the other protease inhibitors had no significant inhibitory effects or, even resulted in deleterious effects. Therefore, the formulation containing one or several inhibitors among these effective inhibitors would be a promising topical preparation of rhEGF for the treatment of open wound.  相似文献   
25.
A total of 106 clinical isolates of Staphylococcus aureus were classified into nine pattern types correlated with gyrA mutations. In 62 strains, mutations were found at a single codon (84, 85, 86 and 88), while 22 strains showed double mutations either at codons 84 and 85 or at codons 84 and 88. The double mutations led to the highest levels of ofloxacin resistance (MIC, >/= 128 mug/ml). All isolates with a single Ser-84--> Leu change had an ofloxacin MIC of 8-128 mug/ml, whereas others showed an MIC range of 8-16 mug/ml. Twenty-two wild type strains and one strain with a single mutation at codon 86 (silent mutation) were ofloxacin-susceptible. Thus, gyrA mutations seem to play a definite role in the high-level of resistance to ofloxacin.  相似文献   
26.
A technique for reconstruction of the medial patellofemoral ligament   总被引:9,自引:0,他引:9  
Additional medial patellofemoral ligament reconstruction was performed successfully on six consecutive patients with recurrent dislocation of the patella because of residual patellar instability after medial transfer of the tibial tubercle. A technique for medial patellofemoral ligament reconstruction is described, and complications and postoperative management are discussed. The reconstruction was performed using a double strand hamstring tendon graft in five patients and iliotibial allograft in one. Good stabilization of the patella was achieved in all six patients, resulting in improved confidence in higher levels of activity. The satisfactory outcome of additional medial patellofemoral ligament reconstruction suggests the possibility that the procedure may be part of the optional procedure in proximal realignment for recurrent dislocation of the patella.  相似文献   
27.
Matsui H, Iitsuka Y, Seki K, Sekiya S. Etoposide (VP-16) as first-line,single agent chemotherapeutic drug in low-risk gestational trophoblasticdisease. Int J Gynecol Cancer 1997; 7: 400–404.
We reviewed the records of 73 patients with low-risk gestationaltrophoblastic disease (GTD) treated with etoposide from 1986 to 1995 at ChibaUniversity. All patients received courses of etoposide every 10 to 14 days until their human chorionicgonadotropin (hCG) concentrations had reached <1 mIU/ml or drug resistanceand/or unacceptable toxicityoccurred. Fifty-one patients (69.9%) were treated with chemotherapyalone and 22 patients (30.1%) also underwent planned hysterectomy.
Sixty-seven patients (92%) achieved a primary remission, while sixpatients (8%) required a change in drugs due to drug resistance (4patients, 5%) or toxicity (2patients, 3%). All 73 patients achieved complete remission. However, onepatient (1.4%) relapsed later.
We have demonstrated that etoposide is one of the most effective drugsagainst GTD and that the short-term toxicity is, except for alopecia,relatively mild and acceptable.Patients should, however, be informed of the possibilities of secondarymalignancies and followed-up cautiously.  相似文献   
28.
Primary carcinoma of the fallopian tube is extremely rare and the preoperative diagnosis is often misdiagnosed as an ovarian carcinoma. We report a patient with primary carcinoma of the fallopian tube, strongly suspected preoperatively on the basis of characteristic clinical symptoms, elevated CA125 levels, and transvaginal sonography, computed tomography, and magnetic resonance imaging findings. The histology of fallopian tube carcinoma was demonstrated as transitional cell carcinoma. Extensive review of the literature showed that our case seemed to be the 14th case of primary transitional cell carcinoma of the fallopian tube.  相似文献   
29.
30.
The involvement of abnormalities of the BRCA1 gene in breast cancers in Japanese patients without any family history of this cancer was investigated by polymerase chain reaction-based single-strand conformation polymorphism analysis of the DNA sequences corresponding to the zinc finger domain (exons 2, 3 and 5) and the binding domain with Rad51 (exon 11) of the BRCA1 protein. An identical nonsense mutation at codon 63 (TTA to TAA) was found in 2 of 56 (3.5%) breast cancers from independent patients. The nucleotide change was also detected in the DNAs from non-cancerous tissues of both patients and therefore was a germline mutation. One of the patients was a member of a pedigree involving 3 ovarian cancer and 1 gastric cancer patients, while the other patient had no family history of malignancy. The same germline mutation at codon 63 was reported in four other independent Japanese pedigrees with frequent breast cancer, but not in such families in other countries. These observations suggest that the mutation commonly originated from a single Japanese ancestor. No other mutation of the BRCA1 gene was observed in the samples analyzed in this study. A low incidence of germline mutation and the absence of somatic mutation suggest that the aberration of the BRCA1 gene is involved only in a subset of Japanese breast cancers.  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