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   20026篇
  免费   1041篇
  国内免费   104篇
耳鼻咽喉   160篇
儿科学   624篇
妇产科学   470篇
基础医学   2384篇
口腔科学   404篇
临床医学   1914篇
内科学   4202篇
皮肤病学   266篇
神经病学   1601篇
特种医学   560篇
外科学   2668篇
综合类   382篇
一般理论   13篇
预防医学   1629篇
眼科学   1133篇
药学   1322篇
  3篇
中国医学   107篇
肿瘤学   1329篇
  2024年   148篇
  2023年   225篇
  2022年   310篇
  2021年   655篇
  2020年   445篇
  2019年   559篇
  2018年   593篇
  2017年   423篇
  2016年   383篇
  2015年   456篇
  2014年   605篇
  2013年   815篇
  2012年   1201篇
  2011年   1230篇
  2010年   717篇
  2009年   644篇
  2008年   1042篇
  2007年   1176篇
  2006年   1051篇
  2005年   1016篇
  2004年   960篇
  2003年   880篇
  2002年   790篇
  2001年   538篇
  2000年   475篇
  1999年   408篇
  1998年   169篇
  1997年   146篇
  1996年   129篇
  1995年   97篇
  1994年   107篇
  1993年   102篇
  1992年   244篇
  1991年   241篇
  1990年   211篇
  1989年   171篇
  1988年   181篇
  1987年   204篇
  1986年   147篇
  1985年   140篇
  1984年   96篇
  1983年   124篇
  1982年   74篇
  1981年   63篇
  1980年   67篇
  1979年   94篇
  1978年   71篇
  1977年   38篇
  1976年   38篇
  1973年   38篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
AIMS/BACKGROUND: alpha-1 antitrypsin (alpha1AT) is an abundant protease inhibitor in human plasma. Its phenotypic variability has been reported to be associated with pulmonary emphysema and chronic liver diseases. However, alpha1AT deficiency is an uncommon condition in the Chinese population. The aim of this study was to describe the phenotypic distribution of alpha1AT in a southern Chinese population. METHODS: A total of 1085 healthy blood donors underwent alpha1AT phenotyping by isoelectric focusing. RESULTS: Two thirds (66.1%) were homozygous for either M1 or M2, whereas 32.6% were heterozygous for two different M phenotypes. The frequency of allelic variants was only 0.007, and deficiency variants were absent. Compared with earlier studies on southern Chinese populations, this study found a lower frequency of M2, and a higher number of allelic variants, including E, L, N, P, and S. This phenomenon can be attributed to population migration and mixing. CONCLUSIONS: An understanding of the alpha1AT pattern is important for evaluating the predisposition of the population to selected clinical diseases.  相似文献   
42.
43.
44.
A Jones  J Grace  B E Hall 《Pathology》1990,22(1):5-9
Twenty cases of non-Hodgkin's malignant lymphoma were examined using both flow cytometry (FCM) and static cytometry (SCM) DNA analysis to detect aneuploidic cell populations. FCM was performed on fresh cell suspensions whilst SCM was performed retrospectively on formalin-fixed, paraffin-embedded samples of the same tissue. A total of 34 aneuploidic cell lines were detected by FCM compared to a total of 41 detected by SCM. Of the 20 cases 14 showed DNA indexes within 10% of each other for each method, indicating a reasonable degree of comparability between the two methods. Of the 6 cases which did not show comparable DNA indexes, 2 displayed similar cell lines for both methods, but the major abnormal cell populations were of different ploidy by SCM as compared to FCM. A qualitative comparison is thus possible between these two cases. The results suggest that retrospectively applied SCM ploidy analysis of lymphoid tissue is comparable to FCM on fresh tissue samples and can thus be used in retrospective studies of both prognostic and diagnostic significance.  相似文献   
45.
A study of the effects of oral acyclovir (200 mg), administered five times per day for 5 days in 210 patients who cultured positive for herpes labialis, is made. A total of 149 patients were followed through three episodes each of herpes labialis while taking a placebo or acyclovir. Patients were evaluated for several clinical parameters, including the loss of lesion crust and reduction of the size of the area of the lesion between day 1 and day 5. Acyclovir showed a significant antiviral effect. Results show that oral acyclovir can favorably affect some parameters, but that higher doses or a "loading dose" could improve its efficacy.  相似文献   
46.
The Journal of Behavioral Health Services & Research - Characterizing community mental health (CMH) treatment duration and discharge is an important step toward understanding how to better meet...  相似文献   
47.
The European Journal of Health Economics - Social support is increasingly acknowledged as an important resource for promoting well-being. We test whether social support changes around retirement....  相似文献   
48.
49.
Tioman virus, a novel paramyxovirus isolated from fruit bats in Malaysia   总被引:18,自引:0,他引:18  
Chua KB  Wang LF  Lam SK  Crameri G  Yu M  Wise T  Boyle D  Hyatt AD  Eaton BT 《Virology》2001,283(2):215-229
A search for the natural host of Nipah virus has led to the isolation of a previously unknown member of the family Paramyxoviridae. Tioman virus (TiV) was isolated from the urine of fruit bats (Pteropus hypomelanus) found on the island of the same name off the eastern coast of peninsular Malaysia. An electron microscopic study of TiV-infected cells revealed spherical and pleomorphic-enveloped viral particles (100--500 nm in size) with a single fringe of embedded peplomers. Virus morphogenesis occurred at the plasma membrane of infected cells and morphological features of negative-stained ribonucleoprotein complexes were compatible with that of viruses in the family Paramyxoviridae. Serological studies revealed no cross-reactivity with antibodies against a number of known Paramyxoviridae members except for the newly described Menangle virus (MenV), isolated in Australia in 1997. Failure of PCR amplification using MenV-specific primers suggested that this new virus is related to but different from MenV. For molecular characterization of the virus, a cDNA subtraction strategy was employed to isolate virus-specific cDNA from virus-infected cells. Complete gene sequences for the nucleocapsid protein (N) and phosphoprotein (P/V) have been determined and recombinant N and V proteins produced in baculovirus. The recombinant N and V proteins reacted with porcine anti-MenV sera in Western blot, confirming the serological cross-reactivity observed during initial virus characterization. The lack of a C protein-coding region in the P/V gene, the creation of P mRNA by insertion of 2-G residues, and the results of phylogenetic analyses all indicated that TiV is a novel member of the genus Rubulavirus.  相似文献   
50.
AIM: To investigate whether PTEN/MMAC1 mutations play a role in the carcinogenesis of oesophageal squamous cell carcinoma. METHODS: A panel of 33 primary oesophageal squamous cell carcinoma tumour samples and 20 corresponding morphologically normal tissues was examined for mutations in all nine exons of the PTEN/MMAC1 gene by means of polymerase chain reaction single strand conformational polymorphism analysis (PCR-SSCP) and direct DNA sequencing methods. RESULTS: Only one of 33 oesophageal squamous cell carcinomas showed an aberrant SSCP band. Further sequencing analysis of this sample revealed an 802 -29 T-->C substitution in intron 7. PTEN/MMAC1 mutations were not found in the mutational "hot spot" in exon 5, even after direct sequencing of six oesophageal squamous cell carcinoma samples and three normal tissues. However, a deletion of one nucleotide T at position 492 +8 in intron 5 was seen in all samples. CONCLUSION: These results suggest that PTEN/MMAC1 mutations do not play a major role in the carcinogenesis of oesophageal squamous cell carcinoma.  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