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   50947篇
  免费   4035篇
  国内免费   1134篇
耳鼻咽喉   305篇
儿科学   1373篇
妇产科学   892篇
基础医学   6952篇
口腔科学   787篇
临床医学   4902篇
内科学   10696篇
皮肤病学   943篇
神经病学   3591篇
特种医学   940篇
外国民族医学   5篇
外科学   4367篇
综合类   4715篇
现状与发展   6篇
一般理论   49篇
预防医学   5450篇
眼科学   725篇
药学   4546篇
  28篇
中国医学   1310篇
肿瘤学   3534篇
  2024年   141篇
  2023年   2921篇
  2022年   6406篇
  2021年   8068篇
  2020年   5563篇
  2019年   1978篇
  2018年   1761篇
  2017年   1486篇
  2016年   1236篇
  2015年   1321篇
  2014年   2025篇
  2013年   1908篇
  2012年   1864篇
  2011年   2148篇
  2010年   1933篇
  2009年   1568篇
  2008年   1527篇
  2007年   1410篇
  2006年   1146篇
  2005年   1009篇
  2004年   969篇
  2003年   757篇
  2002年   573篇
  2001年   482篇
  2000年   500篇
  1999年   407篇
  1998年   324篇
  1997年   269篇
  1996年   267篇
  1995年   213篇
  1994年   162篇
  1993年   148篇
  1992年   122篇
  1991年   122篇
  1990年   98篇
  1989年   80篇
  1988年   64篇
  1987年   58篇
  1985年   353篇
  1984年   520篇
  1983年   326篇
  1982年   346篇
  1981年   377篇
  1980年   252篇
  1979年   293篇
  1978年   165篇
  1977年   137篇
  1976年   81篇
  1975年   60篇
  1973年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Many side-effects of red blood cell transfusion have been described. They include iron-overload, as well as allo- and autoantibody formation against red cells. During storage, erythrocytes undergo complex structural and biochemical changes. It has been suggested that accelerated and/or aberrant forms of the physiological erythrocyte aging process underlie the red cell storage lesion. This storage lesion may contribute to side-effects of transfusion as endothelial damage by release of internal erythrocyte constituents, (pro)inflammatory consequences, hampered microcirculation and oxygen delivery. Understanding the process that determines the fate of red blood cells after transfusion may contribute to the prevention of side-effects after red blood cell transfusion. This should be the focus of research on red blood cell transfusion in clinical transfusion medicine.  相似文献   
102.
A case of primary seminal vesicle carcinoma is reported. The tumor was a CA125-producing adenocarcinoma consisting of fine papillary-tubular, intricate branching or anastomosing glandular structures and was composed of small cuboidal, but occasionally hobnailed, cells with mostly clear, but occasionally granular, cytoplasm. Some tumor cells showed evidence of secretion of seromucinous materials into the interpapillary and cystic space. lmmunohistochemically, almost half of the tumor cells expressed a positive reaction with anti-CAl25, a common serological marker for ovarian epithelial carcinomas; however, no tumor cells expressed any other serological tumor markers such as carcinoem-bryonic antigen, α-fetoprotein, human chorionic gonadotropin, prostatic specific acid phosphatase, or prostatic specific antigen. The patient showed a high level of serological CA125, which fluctuated parallel with the growth, removal and recurrence of the tumor. The morphological and immunohistochemical findings suggested a close relationship between the present tumor and clear cell carcinoma of the ovary, which is thought to be of a Müllerian-Wolfian duct origin.  相似文献   
103.
Matsubara Y  Kure S 《Human mutation》2003,22(2):166-172
Recent advances in human genome research have revealed that genetic polymorphisms, such as single nucleotide polymorphisms (SNPs), are closely associated with susceptibility to various common diseases and adverse drug reactions. Also, numerous mutations responsible for a number of genetic diseases have been identified. Clinical application of genetic information to individual health care requires simple and rapid identification of nucleotide changes in clinical settings. We have devised a novel low-tech method for the detection of a single nucleotide substitution using competitive allele-specific short oligonucleotide hybridization with immunochromatographic strip. The gene of interest is PCR-amplified, hybridized to an allele-specific short oligonucleotide probe in the presence of a competitive oligonucleotide, and subjected to chromatography using a DNA test strip at room temperature. The genotype is unambiguously determined by the presence or the absence of visible purple lines on a strip. Feasibility of the method was demonstrated by the detection of a prevalent disease-causing mutations in glycogen storage disease type Ia (G6PC), medium-chain acyl-CoA dehydrogenase deficiency (ACADM), non-ketotic hyperglycinemia (GLDC), and clinically important polymorphisms in the CYP2C19 gene and the aldehyde dehydrogenase 2 gene (ALDH2). The procedure does not demand either technical expertise or expensive instruments and is readily performed in local clinical laboratories. The result is obtained within 10 min after PCR. This rapid and simple method of SNP detection may be used for point-of-care genetic diagnosis with potentially diverse clinical applications. Hum Mutat 22:166-172, 2003.  相似文献   
104.
《Immunity》2022,55(3):542-556.e5
  1. Download : Download high-res image (228KB)
  2. Download : Download full-size image
  相似文献   
105.
106.
107.
Mitochondrial DNA polymorphisms in Yunnan nationalities in China   总被引:4,自引:0,他引:4  
Nucleotide sequences of the D-loop region of human mitochondrial DNA from four Yunnan nationalities, Dai, Wa, Lahu, and Tibetan, were analyzed. Based on a comparison of 563-bp sequences in 99 people, 66 different sequence types were observed. Of these, 64 were unique to their respective populations, whereas only 2 types were shared between the Lahu and Wa nationalities. The D-loop sequence variation and phylogenetic analysis suggested that the 99 mtDNA lineages were classified into eight clusters in the phylogenetic tree. All lineages that had a 9-bp deletion in the COII/tRNALys intergenic region appeared in one cluster in the D-loop tree, suggesting a single event of the deletion in the Yunnan nationalities studied. Genetic distances, based on net nucleotide diversities between populations including Han Chinese and mainland Japanese, revealed that the Dai, Wa, Lahu, and Han Chinese are closely related to each other, while Tibetan and mainland Japanese formed a single cluster. The bootstrap probabil-ity of separation between the Dai-Wa-Lahu-Chinese clade and the Tibetan-Japanese clade was 99%, indicating that there are at least two different origins among minority groups in Yunnan province. Although the genetic distance between Tibetan and Japanese within the clade is rather long, the results may shed light on the origins of mainland Japanese. Received: December 22, 2000 / Accepted: January 18, 2001  相似文献   
108.
To assess the performance of continuous positive airway pressure devices in treatment of sleep breathing disorders during polysomnographic studies, analysis are based essentially on the patient airflow signal measured by a pneumotachograph and the mask pressure. These signals used either by the softwares or the physicians provide powerful information on respiratory events occurring during the night. However, sometimes signals are artifacted by airflow leaks at the mask or the mouth. These artifacts are causes of information loss and then of possible wrong interpretations. We studied the relationship between airflow and mask pressure at the occurrence of leaks. We used analogy with electrical models and Kirchoff laws to estimate mask leaks and to detect mouth breathing. A Starling model connected to a flow generator simulated respiratory movements. A positive pressure was maintained in the model and artificial leaks comparable to mask leaks were provoked. Then, we replaced the Starling model and the flow generator by two healthy volunteers. We computed mask leaks in both conditions and found no contradiction between the simulated model and the subjects. Equations of the analog circuit were helpful to assess mask leaks and to detect mouth breathing. Such equations could be included in polysomnographs or in pressure generator algorithms either for detecting leaks or adjusting airway pressure.  相似文献   
109.
The histopathology of papillary thyroid hyperplasia and papillary thyroid carcinoma is similar enough to cause a diagnostic dilemma in a few cases. Both lesions may have papillary fronds with fibrovascular cores, nuclear crowding, and nuclear anisocytosis. Formalin-fixed paraffin-embedded tissues from 30 randomly selected patients with papillary thyroid hyperplasia and an equal number from patients with papillary thyroid carcinoma were analyzed for expression of cytokeratin 19 (CK19), galectin-3, and HBME-1. Cases of papillary thyroid carcinoma had moderate to strong CK19, galectin-3, and HBME-1 reactivity although both CK19 and galectin-3 showed positive staining in a significant number of nonneoplastic thyroid cases. HBME-1 was uncommon in the nonneoplastic cases. These results indicate that HBME-1 may be useful in helping to distinguish papillary thyroid carcinoma from hyperplasia in diagnostically difficult cases.  相似文献   
110.
Micronuclei and other biomarkers were evaluated in oral cells from 11- to 16-year-old girls living in a foster home in the central area of México City. Variables analyzed for possible association with these biomarkers include smoking habits, body mass index, metabolic polymorphisms for NAT1 and GSTM1 and whether the cells were obtained from the cheek or pharynx. The results indicated that individuals having the NAT1*10 homozygous genotype showed a significant increase in chromatin buds and binucleated cells. When the damage in the cheek was compared with damage in the pharynx, a significant increase in micronuclei and binucleated cells was found for the latter tissue in all the individuals analyzed.  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