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   2039篇
  免费   94篇
  国内免费   10篇
耳鼻咽喉   13篇
儿科学   72篇
妇产科学   56篇
基础医学   218篇
口腔科学   26篇
临床医学   183篇
内科学   403篇
皮肤病学   40篇
神经病学   97篇
特种医学   198篇
外科学   369篇
综合类   65篇
预防医学   129篇
眼科学   27篇
药学   112篇
中国医学   7篇
肿瘤学   128篇
  2023年   24篇
  2022年   32篇
  2021年   56篇
  2020年   44篇
  2019年   64篇
  2018年   54篇
  2017年   37篇
  2016年   36篇
  2015年   46篇
  2014年   89篇
  2013年   93篇
  2012年   123篇
  2011年   132篇
  2010年   63篇
  2009年   61篇
  2008年   99篇
  2007年   112篇
  2006年   114篇
  2005年   89篇
  2004年   74篇
  2003年   66篇
  2002年   47篇
  2001年   29篇
  2000年   42篇
  1999年   26篇
  1998年   43篇
  1997年   40篇
  1996年   24篇
  1995年   20篇
  1994年   23篇
  1993年   14篇
  1992年   29篇
  1991年   15篇
  1990年   22篇
  1989年   22篇
  1988年   17篇
  1987年   19篇
  1986年   17篇
  1985年   14篇
  1983年   10篇
  1982年   13篇
  1981年   11篇
  1979年   11篇
  1978年   11篇
  1977年   11篇
  1975年   12篇
  1973年   13篇
  1972年   10篇
  1971年   11篇
  1968年   11篇
排序方式: 共有2143条查询结果,搜索用时 7 毫秒
1.
2.
3.
4.
A convenient approach to the new 2-aminobenzophenone analogue 4 is reported. Condensation reactions of 4 with ortho esters or amide acetals, respectively, followed by intramolecular cyclisations were found to provide smooth access to (4-pyridazinyl)-substituted quinolines 10, 13a,b , and the quinazoline derivative 15 .  相似文献   
5.
Systemic angioendotheliomatosis is a very rare malignant disease characterized by intravascular neoplastic proliferation of reticuloendothelial cells. According to the clinical features three different types of prognostic value can be distinguished: Exclusive skin involvement; Progressive skin lesions disseminating to internal organs; Aggressive and lethal type affecting primarily internal organs. Until now about 60 cases of systemic angioendotheliomatosis have been reported in the literature. Here we describe the first well-documented case with almost isolated lung involvement. The presentation of morphologic and clinical signs and differential-diagnostic considerations are followed by a critical review of the literature.  相似文献   
6.
Budd–Chiari syndrome (BCS) is characterized by obstruction of the hepatic venous outflow tract. Therapeutic options for BCS are limited. We report a case of a 21-year-old woman with protein S and C deficiency with gross ascites. Treatment with transjugular intrahepatic portosystemic shunt (TIPS) was attempted, which revealed occluded hepatic veins, so transcaval TIPS was performed. No serious procedure-related complication occurred. After successful shunt creation, the patient's symptoms subsided and she was discharged and followed up for 6 months.  相似文献   
7.
Kaplan  PA; Reiskin  AB; Tu  HK 《Radiology》1987,163(1):217-220
Arthrograms of the temporomandibular joint were obtained in 20 symptomatic joints that had previous reconstructive arthroplasty with disk repositioning because of internal derangements. Preoperative arthrograms were available for comparison in 18 joints. Symptoms resulting in a postoperative arthrogram included pain, limited ability to open the mouth, and clicking of the joints. Postoperative arthrographic findings included limited anterior translation of the condyle (90%), irregularity in outline of the intraarticular contrast agent (60%), a conical configuration of the posterior recess (25%), decreased size of the joint (28%), anterior displacement of the meniscus (25%), and perforated meniscus (15%). Many of these findings may have resulted from fibrosis and scarring, which may be a response to intraarticular bleeding. The mechanism by which the fibrosis causes the postsurgical arthrographic features is discussed.  相似文献   
8.
Localized, diffuse, and aggregative adherence patterns of Escherichia coli identified with specific DNA probes were compared in cell culture adherence assays by using the Center for Vaccine Development, Baltimore, method, the University of Texas Medical School, Houston (UTH), method, and a modified UTH method. Increasing postwash incubation time from 2 to 4 h in the modified UTH method allowed identification of enteroaggregative E. coli, which was otherwise not identified by the original UTH method.  相似文献   
9.
The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by P. falciparum isolates from three African countries. Plasma levels of VSA-specific IgG recognizing individual parasite isolates depended on the transmission intensity at the site of plasma collection but were largely independent of the geographical origin of the parasites. The total repertoire of immunologically distinct VSA thus appears to be finite and geographically conserved, most likely due to functional constraints. Furthermore, plasma samples frequently had high IgG reactivity to VSA expressed by parasites isolated more than 10 years later, showing that the repertoire is also temporally stable. Parasites from patients with severe malaria expressed VSA (VSASM) that were better recognized by plasma IgG than VSA expressed by other parasites, but importantly, VSASM-type antigens also appeared to show substantial antigenic homogeneity. Our finding that the repertoire of immunologically distinct VSA in general, and in particular that of VSASM, is geographically and temporally conserved raises hopes for the feasibility of developing VSA-based vaccines specifically designed to accelerate naturally acquired immunity, thereby enhancing protection against severe and life-threatening P. falciparum malaria.  相似文献   
10.
Traditional enteropathogenic Escherichia coli serotypes demonstrate a plasmid-mediated localized adherence in cultured HeLa or HEp-2 cells and induce an attaching-effacing intestinal lesion, both of which are considered pathognomonic and causes of diarrhea. This study describes three E. coli strains from infantile diarrhea which share these properties but belong to serotypes (O2:H2, O2:H25 and O15:H2) not considered enteropathogenic.  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