首页 | 官方网站   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   1719篇
  免费   174篇
  国内免费   119篇
医药卫生   2012篇
  2020年   13篇
  2019年   16篇
  2018年   26篇
  2017年   12篇
  2016年   13篇
  2015年   30篇
  2014年   32篇
  2013年   63篇
  2012年   49篇
  2011年   43篇
  2010年   57篇
  2009年   47篇
  2008年   51篇
  2007年   127篇
  2006年   68篇
  2005年   55篇
  2004年   65篇
  2003年   51篇
  2002年   48篇
  2001年   59篇
  2000年   65篇
  1999年   54篇
  1998年   59篇
  1997年   40篇
  1996年   39篇
  1995年   39篇
  1994年   40篇
  1993年   31篇
  1992年   49篇
  1991年   48篇
  1990年   52篇
  1989年   60篇
  1988年   54篇
  1987年   40篇
  1986年   26篇
  1985年   30篇
  1984年   29篇
  1983年   17篇
  1982年   25篇
  1981年   18篇
  1980年   16篇
  1979年   16篇
  1978年   20篇
  1977年   16篇
  1976年   18篇
  1975年   17篇
  1971年   11篇
  1968年   18篇
  1966年   10篇
  1958年   15篇
排序方式: 共有2012条查询结果,搜索用时 296 毫秒
11.
The authors analyzed poisoning-related deaths in Massachusetts from 1986 and 1987 recorded in three datasets: poison center records, death certificate, and state medical examiner's office records. While 714 such deaths were found, 551 of these were prehospital deaths recorded within the medical examiner's office but not by the poison center. The poison center was not consulted in over 47% of the poisoning deaths occurring in Massachusetts hospitals. Conversely, 15% of deaths were reported to the poison center but were not found either in death certificate or medical examiner records. Concordance between all three datasets for recording the 163 poisoning-related hospital deaths was only 17%. The authors conclude that reliance on a single data source underestimates and potentially misrepresents both the numbers and types of poisoning deaths occurring in the state. They also believe the files of the medical examiner are an underappreciated, rich source of data concerning out-of-hospital deaths due to poisonings and intoxications. Their findings suggest that the regional poison center is an underused resource for the management of seriously poisoned patients. There is a need for a better working relationship between poison centers and area hospitals so that all serious intoxications and poisonings are reported to the poison center in a timely fashion.  相似文献   
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.
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   
14.
报道了用GC/MS方法及衍生化技术研究6甲氧基正丁苯酞(MBP)在大鼠肝微粒体中的代谢转化结果。6甲氧基正丁苯酞在苯巴比妥(PB)诱导的大鼠肝微粒体中主要转化为3羟基、γ羟基取代物,6羟基正丁苯酞与一个环氧化代谢产物  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.
Human peripheral nerves obtained by biopsy from patients suffering from neuromuscular disorders have been studied by x-ray diffraction and electron microscopy. Few abnormal diffraction patterns have yet been recorded and their significance is not yet established. Electron micrographs have revealed wide variations in the numbers of myelinated fibres included in the nerve trunks and have facilitated a detailed study of the Schwann cell-axon relationships in the large numbers of unmyelinated fibres always present. Some indications of demyelination have been encountered.  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.
The effect of naloxone on C-primary afferent-mediated inhibitions of C-fibre-evoked activity in deep dorsal horn neurones has been examined in decerebrate-spinal rats. The same C-afferents that evoke activity in a given neurone can inhibit that C-evoked activity (homosynaptic inhibition), and C-afferent input can also inhibit the activity evoked in dorsal horn neurones by other C-afferents (heterosynaptic inhibition). Naloxone was found to selectively reverse heterosynaptic C-mediated inhibitions without affecting homosynaptic inhibitions. In several neurones the heterosynaptic inhibitions were completely abolished by naloxone. These results show that homo- and heterosynaptic C-mediated inhibitions operate by different mechanisms and that, at least in some neurones, endogenous opioids are likely to be the major inhibitory transmitters involved in producing the heterosynaptic inhibition of the activity evoked by one C-input by another C-input.  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-23

京公网安备 11010802026262号