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   11470篇
  免费   1033篇
  国内免费   50篇
耳鼻咽喉   134篇
儿科学   449篇
妇产科学   224篇
基础医学   1710篇
口腔科学   284篇
临床医学   1459篇
内科学   2499篇
皮肤病学   194篇
神经病学   1068篇
特种医学   544篇
外国民族医学   2篇
外科学   1332篇
综合类   282篇
一般理论   7篇
预防医学   940篇
眼科学   130篇
药学   678篇
中国医学   7篇
肿瘤学   610篇
  2021年   105篇
  2019年   104篇
  2018年   151篇
  2017年   137篇
  2016年   155篇
  2015年   157篇
  2014年   214篇
  2013年   369篇
  2012年   419篇
  2011年   402篇
  2010年   280篇
  2009年   267篇
  2008年   413篇
  2007年   473篇
  2006年   458篇
  2005年   411篇
  2004年   396篇
  2003年   394篇
  2002年   375篇
  2001年   377篇
  2000年   371篇
  1999年   335篇
  1998年   192篇
  1997年   191篇
  1996年   217篇
  1995年   161篇
  1994年   143篇
  1993年   159篇
  1992年   268篇
  1991年   245篇
  1990年   258篇
  1989年   278篇
  1988年   272篇
  1987年   265篇
  1986年   206篇
  1985年   209篇
  1984年   183篇
  1983年   129篇
  1982年   98篇
  1981年   129篇
  1980年   120篇
  1979年   141篇
  1978年   115篇
  1977年   131篇
  1976年   124篇
  1975年   121篇
  1974年   95篇
  1972年   94篇
  1969年   88篇
  1960年   79篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Physicians' attitudes on advance directives   总被引:7,自引:0,他引:7  
K W Davidson  C Hackler  D R Caradine  R S McCord 《JAMA》1989,262(17):2415-2419
Advance directives provide means for competent individuals to influence treatment decisions in the event of serious illness and subsequent loss of competence, the "living will" being the best known example. Physicians in Arkansas who were identified to be currently engaged in general practice, family medicine, or internal medicine, including its subspecialities (N = 1293), were surveyed to assess attitudes toward and experiences with advance directives. Almost 80% of all respondents expressed a positive attitude and fewer than 2% expressed a negative attitude toward such documents. A majority (55.9%) had actual experience with the instruments in their practices, and 83.5% of these physicians said that their attitude had become more positive as a result of their experience. More frequent employment of advance directives in critical situations was associated with more positive attitudes and experiences. Most of the benefits claimed for advance directives--improved communication and trust, easier and more confident treatment decision, less stress and guilt, and promotion of patient autonomy--were substantiated by the results.  相似文献   
52.
53.
The Second International Nonhuman Primate Histocompatibility Workshop permitted comparison of rhesus monkey alloantisera developd in various laboratories on a single common panel of related and unrelated monkeys. Analysis of the data permits the conclusion that at least nine specificities are recognized by more than one laboratory, including six at the first locus and three at the second locus.  相似文献   
54.
We immunohistochemically analyzed kallikrein 4 protein (hK4) expression in patients with epithelial ovarian carcinoma (181 malignant effusions and 103 solid carcinoma lesions). Expression of hK4 was also studied in 32 effusions using immunoblotting. Carcinoma cells expressed hK4 in 144 (79.6%) of 181 effusions and 85 (82.5%) of 103 solid tumors. Expression was seen in 51% or more of tumor cells in 70 effusions but often was limited to 5% or fewer cells in solid tumors (P = .009, primary tumors vs effusions; P = .002, metastases vs effusions). Immunoblotting showed hK4 expression in 31 of 32 specimens. Stromal cell hK4 expression, seen in 48 (46.6%) of 103 lesions, was significantly higher in primary tumors than metastases (26/43 vs 22/60, P = .019). hK4 expression in tumor cells was significantly lower in International Federation of Gynecology and Obstetrics stage IV than stage III tumors (P = .004, all lesions; P = .012, primary tumors). hK4 expression in carcinoma cells was associated with longer overall survival (not significant; P = .14, peritoneal effusions). hK4 is expressed widely in ovarian carcinoma; levels in carcinoma cells are highest in effusions, which might be related to loss of stromal contribution and/or altered microenvironment. hK4 expression in carcinoma cells of effusions or solid tumors does not predict survival.  相似文献   
55.
A radioactive PCR test was developed that amplified the very virulent Marek's disease virus-1 (vvMDV-1) DNA sequence containing the 132 bp repeats. In apathogenic MDV-1 (CVI 988, Rispens), amplified DNA bands containing multiple copies of 132 bp repeats were identified. In the present study this PCR technique was used to monitor the passage level of vvMDV-1 in chicken embryo fibroblasts (CEF) in which the number of tandem 132 bp repeats was increased. It was found that at passage level 32 of vvMDV-1-B isolate, the 132 bp tandem repeat was already markedly amplified and its pattern resembled that of the MDV-1 (CVI 988, Rispens) vaccine virus DNA. In the vvMDV-1Z strain, amplification of the 132 bp repeat was not detectable at a similar passage level. The PCR test demonstrated that the apathogenic MDV-1 Md11/75c virus developed by extensive in vitro passaging has amplified 132 bp DNA repeats similar to those of the commercial vaccine virus (CVI 988, Rispense). It was also found that the pattern of viral RNA from infected cells detectable by Northern blot hybridization was markedly changed from a 2.4 kb RNA species in cells infected with vvMDV-1 viruses, to four RNA species (ranging from 2.2 to 4.4 kb) in cells infected with passage 32 of MDV-1-B strain, to a very large number of undefined RNA species synthesized in cells infected with attenuated MDV-1 viruses (CVI 988, Rispens and Md 11/75c).  相似文献   
56.
Immunoglobulin G, appearing after several months in the serum of a recipient of a successful kidney transplant from a closely matched sibling donor, was demonstrated to progressively inhibit unidirectional mixed lymphocyte cultures when donor lymphocytes were used either in responding or stimulating cell populations. The active recipient IgG had no effect in cultures in which donor cells were not used, nor did IgG obtained from other individuals show nonspecific inhibitory effects on cultures containing donor cells. It is suggested that the MLC inhibitory immunoglobulin may serve an immunoregulatory function after renal transplantation.  相似文献   
57.
AIMS: Previous studies investigating the link between infection with Borrelia burgdorferi and morphoea have produced conflicting results. Often, these studies have been undertaken in patients from different regions or countries, and using methods of varying sensitivity for detecting Borrelia burgdorferi infection. This study aimed to establish whether a relation could be demonstrated in the Highlands of Scotland, an area with endemic Lyme disease, with the use of a sensitive method for detecting the organism. METHODS: The study was performed on biopsies of lesional skin taken from 16 patients from the Highlands of Scotland with typical clinical features of morphoea. After histological confirmation of the diagnosis, a nested polymerase chain reaction (PCR) using primers to a unique conserved region of the Borrelia burgdorferi flagellin gene was performed on DNA extracts from each biopsy. A literature search was also performed for comparable studies. RESULTS: None of the 16 patients had documented clinical evidence of previous infection with B burgdorferi. DNA was successfully extracted from 14 of the 16 cases but all of these were negative using PCR for B burgdorferi specific DNA, despite successful amplification of appropriate positive controls in every test. The results were compared with those of other documented studies. CONCLUSIONS: Examination of the literature suggests that there is a strong geographical relation between B burgdorferi and morphoea. These results, in which no such association was found, indicate that morphoea may not be associated with the subspecies of B burgdorferi found in the Highlands of Scotland.  相似文献   
58.
59.
60.
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