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   1726篇
  免费   76篇
  国内免费   115篇
耳鼻咽喉   8篇
儿科学   57篇
妇产科学   50篇
基础医学   137篇
口腔科学   30篇
临床医学   239篇
内科学   404篇
皮肤病学   38篇
神经病学   48篇
特种医学   110篇
外科学   171篇
综合类   61篇
预防医学   241篇
眼科学   25篇
药学   238篇
中国医学   12篇
肿瘤学   48篇
  2023年   12篇
  2022年   37篇
  2021年   51篇
  2020年   27篇
  2019年   48篇
  2018年   44篇
  2017年   35篇
  2016年   39篇
  2015年   56篇
  2014年   76篇
  2013年   103篇
  2012年   106篇
  2011年   115篇
  2010年   81篇
  2009年   86篇
  2008年   75篇
  2007年   129篇
  2006年   63篇
  2005年   59篇
  2004年   51篇
  2003年   46篇
  2002年   34篇
  2001年   28篇
  2000年   30篇
  1999年   34篇
  1998年   48篇
  1997年   34篇
  1996年   31篇
  1995年   26篇
  1994年   28篇
  1993年   19篇
  1992年   14篇
  1991年   16篇
  1990年   19篇
  1989年   20篇
  1988年   32篇
  1987年   16篇
  1986年   12篇
  1985年   11篇
  1984年   7篇
  1982年   6篇
  1981年   9篇
  1980年   9篇
  1978年   5篇
  1977年   7篇
  1976年   10篇
  1975年   12篇
  1974年   6篇
  1973年   7篇
  1958年   14篇
排序方式: 共有1917条查询结果,搜索用时 31 毫秒
11.
12.
SUMMARY Elevated plasma levels of Lp(a) do seem to influence the progression of atherosclerosis. Evidence is emerging that certain apo(a) isoforms may be more atherogenic than others, and in transgenic mice free apo(a) has been shown to be associated with accelerated atherosclerosis. Currently it is not known whether treating elevated Lp(a) levels will reduce progression of atherosclerosis and, as therapeutic options are limited, mass screening of Lp(a) levels in populations is not indicated. The presence of raised Lp(a) levels, however, warrants aggressive treatment to reduce other cardiovascular risk factors. Continuing research to investigate the relationship of the apo(a) gene to other genes, including the plasminogen gene and apo(a)-related genes, will add further information pertaining to the evolution, function, regulation and clinical implications of Lp(a).  相似文献   
13.
Approximately 5% of Americans over age 65, or 1.5 million individuals, currently reside in the nations's 20,000 nursing homes. The authors present material that lead to three conclusions about this population. First, nutritional deficiencies are common underlying causes of adverse clinical outcomes. Second, nutritional deficiencies are frequently not recognized. Third, opportunities for preventing or correcting undernutrition exist, provided that the significant and reversible nature of the nutrient deficiencies are identified.  相似文献   
14.
BACKGROUND: Autoantibody production by the fetus is thought to be extremely unlikely. Only one possible case of in utero autoantibody production against red cells by the fetus has previously been described. STUDY DESIGN AND METHODS: A case of apparent red cell IgG autoantibody production in utero is reported. RESULTS: This was established by a positive direct antiglobulin test in a newborn infant without evidence of maternal alloantibodies or autoantibodies. There was no evidence of clinically significant hemolysis at the infant's birth. After 6 weeks, his direct antiglobulin test remained strongly positive. The infant thrived without evidence of hemolysis, and after 6 months the direct antiglobulin test was negative. CONCLUSION: The production of autoantibodies to red cells in utero is possible, though rare. This did not result in apparent hemolysis in this patient.  相似文献   
15.
Image-directed percutaneous biopsies with a biopsy gun   总被引:3,自引:0,他引:3  
Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.  相似文献   
16.
17.
This article describes the identification of a novel locus (DFNB39) responsible for an autosomal recessive form of hearing loss segregating in a Pakistani consanguineous family. The hearing impaired members of this family present with profound prelingual sensorineural hearing impairment and use sign language for communications. Linkage was established to microsatellite markers located on chromosome 7q with a maximum multipoint lod score of 3.8. The region of homozygosity spans a 19 cM region that is bounded by markers D7S3046 and D7S644.  相似文献   
18.
The world's first deliveries of normal babies after use of flow cytometric separated human sperm cells (MicroSort) for preconception gender selection are reported. Offspring were of the desired female gender in 92.9% of the pregnancies. Most of these pregnancies and births were achieved after simple intrauterine insemination.   相似文献   
19.
An RNA-binding motif (RBM) gene family has been identified on the human Y chromosome that maps to the same deletion interval as the 'azoospermia factor' (AZF). We have identified the homologous gene family (Rbm) on the mouse Y with a view to investigating the proposal that this gene family plays a role in spermatogenesis. At least 25 and probably >50 copies of Rbm are present on the mouse Y chromosome short arm located between Sry and the centromere. As in the human, a role in spermatogenesis is indicated by a germ cell-specific pattern of expression in the testis, but there are distinct differences in the pattern of expression between the two species. Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are female due to a position effect resulting in non-expression of Sry ; sex-reversing such mice with an Sry transgene produces males with a high incidence of abnormal sperm, making this the third deletion interval on the mouse Y that affects some aspect of spermatogenesis. Most of the copies of Rbm map to this deletion interval, and the Yd1males have markedly reduced Rbm expression, suggesting that RBM deficiency may be responsible for, or contribute to, the abnormal sperm development. In man, deletion of the functional copies of RBM is associated with meiotic arrest rather than sperm anomalies; however, the different effects of deletion are consistent with the differences in expression between the two species.   相似文献   
20.
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