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   15550篇
  免费   1029篇
  国内免费   94篇
耳鼻咽喉   112篇
儿科学   445篇
妇产科学   448篇
基础医学   2043篇
口腔科学   258篇
临床医学   1034篇
内科学   3240篇
皮肤病学   292篇
神经病学   1263篇
特种医学   536篇
外国民族医学   1篇
外科学   2192篇
综合类   176篇
一般理论   7篇
预防医学   1357篇
眼科学   319篇
药学   1099篇
中国医学   71篇
肿瘤学   1780篇
  2023年   90篇
  2022年   249篇
  2021年   473篇
  2020年   290篇
  2019年   333篇
  2018年   426篇
  2017年   316篇
  2016年   330篇
  2015年   429篇
  2014年   504篇
  2013年   688篇
  2012年   899篇
  2011年   877篇
  2010年   601篇
  2009年   517篇
  2008年   767篇
  2007年   784篇
  2006年   742篇
  2005年   654篇
  2004年   694篇
  2003年   632篇
  2002年   645篇
  2001年   542篇
  2000年   480篇
  1999年   439篇
  1998年   189篇
  1997年   135篇
  1996年   142篇
  1995年   137篇
  1994年   102篇
  1993年   102篇
  1992年   263篇
  1991年   229篇
  1990年   223篇
  1989年   226篇
  1988年   182篇
  1987年   136篇
  1986年   156篇
  1985年   138篇
  1984年   106篇
  1983年   81篇
  1982年   50篇
  1981年   47篇
  1979年   61篇
  1975年   37篇
  1974年   39篇
  1973年   38篇
  1969年   41篇
  1968年   46篇
  1967年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Mucosal leishmaniasis of the upper respiratory tract is usually associated with the visceral form or is found in immunosuppressed individuals. This report presents a case of isolated mucosal leishmaniasis in an immunocompetent patient, whose diagnosis mainly rested on histology and positive polymerase chain reaction result for Leishmania donovani in the laryngeal tissue. A 59-year-old man, who never lived outside Italy, showed a subglottic mucosal polypoid-like lesion. The typical morphological picture and positive polymerase chain reaction result for L donovani by DNA extracted from laryngeal biopsy specimens allowed the diagnosis of mucosal leishmaniasis. Specific amphotericin B therapy was started, resulting in clinical and endoscopic improvement. Increased knowledge about the histological and molecular tissue analysis of Leishmania enhances the diagnostic testing for mucosal leishmaniasis, as primary mucosal leishmaniasis may occur in both immunosuppresed and immunocompetent patients who travel to or reside in areas endemic for Leishmania.  相似文献   
52.
Hepatocyte growth factor (HGF), a stimulator of angiogenesis and cell migration, regulates the growth of a wide variety of cells by binding to its high-affinity receptor met and is involved in the growth and aggressiveness of several tumors. In this study we investigated the expression of HGF and met in normal endocrine cells and related neoplasms of the gut and pancreas to verify their possible role in tumor pathogenesis, growth, and aggressiveness. Normal tissues and 60 different endocrine tumors were immunostained using specific antibodies directed against HGF, met, and various hormones. HGF immunoreactivity (IR) was found in antroduodenal G cells, rectal enterochromaffin (EC) cells, and pancreatic A and B cells, whereas met IR was detected in antral EC and G cells, and in pancreatic B cells; 46 of 60 tumors examined were positive for HGF, and they were mainly represented by ECL-, EC-, and L-cell neoplasms. met IR was identified in 50/60 tumors of various phenotypes. HGF and met coexpression was found in 42/60 cases, most of which were represented by EC-cell tumors. HGF/met coexpression was significantly more frequent in ileolonic EC-cell tumors, which in the majority of cases were malignant, than in appendiceal EC-cell tumors, which were all benign. Our results demonstrated, for the first time, that HGF and met are specifically distributed in normal gut and pancreatic endocrine cells and, in addition, suggest that HGF and met may be implicated as autocrine/paracrine factors regulating the growth of gastroenteropancreatic endocrine tumors, mainly of ileocolonic EC-cell carcinoids.  相似文献   
53.
54.
The major indications for the clinical use of oestrogen and progestogen are oral contraception (OC) in young women, and hormonal replacement therapy (HRT) in menopause. Over the past few years, epidemiological data have associated the use of these hormones to different cardiovascular conditions such as myocardial infarction, cerebrovascular disease and venous thromboembolism. This review summarizes the data discussed and the conclusions achieved by the ESHRE Capri Workshop Group, recently published in Human Reproduction.  相似文献   
55.
In the original version of this article, the title was incorrect. Please find the correct title given here. The publisher deeply regrets this error. The original article to which this Erratum refers was published in Human Mutation 22:179–180 Human Mutation(2003) 22(2) 179–180  相似文献   
56.
Capillary electrophoretic (CE) profiling analysis combined with pattern recognition methods is described for the correlation between urinary nucleoside profiles and uterine cervical cancer. Nucleosides were extracted from urine specimens by solid-phase extraction in affinity mode using phenylboronic acid gel. CE separation was carried out with an uncoated fused-silica capillary (570 mm x 50 microm I.D.) maintained at 20 degrees C, using 25 mM borate-42.5 mM phosphate buffer (pH 6.7) containing 200 mM sodium dodecyl sulfate as the run buffer under the applied voltage of 20 kV. A total of 15 nucleosides were positively identified in urine samples (2 ml) from eight uterine myoma (benign tumor group), 10 uterine cervical cancer (malignant tumor group) patients and 10 healthy females (normal group) studied. The star symbol plots drawn based on each mean concentration of nucleosides normalized to that in normal group enabled one to discriminate malignant and benign groups from normal group. In addition, canonical discriminant analysis performed on the nucleoside data of 28 individual urine specimens correctly classified into three separate clusters according to groups in the canonical plot.  相似文献   
57.
We herein report one case of culture-negative infectious endocarditis (IE) where the organism, Granulicatella elegans, was identified by molecular analysis using broad-range PCR primers complementary to the 16S rRNA gene on the removed valve. The results and utility of this method are discussed.  相似文献   
58.
59.
A sample of aphthovirus type C3 strain Resende carrying two polyribocytidilic acid [poly(C)] tracts was cloned in tissue culture. One clone with a poly(C)-rich tract of about 145 nucleotides long (clone 3B) and another with a poly(C)-rich tract of about 230 nucleotides long (clone 12) and a mixture of both were injected intralingually into three steers. Samples from all three animals were recovered during the acute phase of the disease, from the blood and from the feet, and at various days after inoculation from the oesophageal-pharyngeal (OP) fluids. Analysis of the viral RNAs of the positive samples by means of RNase T1 maps on one- and two-dimensional gels showed (1) changes in the electrophoretic mobility of the poly(C)-rich tracts of viruses recovered from the OP fluids at various times after infection; (2) selection of virus populations with poly(C)-rich tracts of increased size; (3) later on, changes in the patterns of oligonucleotides of persistent viruses. These variations may lead to the production of new strains with altered biological properties that may contribute to the maintenance and spread of these viruses in the field.  相似文献   
60.
A new training system was designed and realised by the engineer G. Scuderi: a centrifugal track for runners. The principal advantage of this track is to increase the forces on athlete during the run with an effect very similar to that of an "artificial gravity", so the athlete can develop more muscle power. A multibody numerical model of a runner was developed to analyse the behaviour of the athlete on the centrifugal track. The multibody model was calibrated by experimental analysis; in fact, the joint angles were measured by a digital image processing system and introduced as input in the numerical simulation. The numerical results obtained are the values of many kinematic and dynamic variables, in particular the ground reaction force and the moments in the hip, knee, and ankle joints. A comparison between the normal running and that on the centrifugal track was carried out, demonstrating the validity of training on the latter. The results of the numerical simulation confirm that the power developed during running on the track, and the corresponding work performed by the joints, is considerably greater than that found during normal running.  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