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   1504篇
  免费   80篇
  国内免费   9篇
耳鼻咽喉   2篇
儿科学   77篇
妇产科学   49篇
基础医学   194篇
口腔科学   11篇
临床医学   167篇
内科学   446篇
皮肤病学   9篇
神经病学   70篇
特种医学   21篇
外科学   200篇
综合类   4篇
预防医学   105篇
眼科学   19篇
药学   94篇
肿瘤学   125篇
  2023年   9篇
  2022年   16篇
  2021年   43篇
  2020年   18篇
  2019年   21篇
  2018年   23篇
  2017年   16篇
  2016年   21篇
  2015年   28篇
  2014年   37篇
  2013年   49篇
  2012年   70篇
  2011年   72篇
  2010年   51篇
  2009年   43篇
  2008年   65篇
  2007年   93篇
  2006年   72篇
  2005年   78篇
  2004年   59篇
  2003年   47篇
  2002年   53篇
  2001年   47篇
  2000年   43篇
  1999年   36篇
  1998年   15篇
  1997年   16篇
  1996年   16篇
  1994年   12篇
  1993年   10篇
  1992年   26篇
  1991年   21篇
  1990年   36篇
  1989年   23篇
  1988年   28篇
  1987年   28篇
  1986年   29篇
  1985年   28篇
  1984年   20篇
  1983年   23篇
  1982年   10篇
  1981年   9篇
  1980年   9篇
  1979年   12篇
  1976年   10篇
  1974年   12篇
  1973年   8篇
  1972年   10篇
  1971年   8篇
  1970年   10篇
排序方式: 共有1593条查询结果,搜索用时 31 毫秒
31.
L E Nava  J M Malacara 《Endocrinology》1987,121(4):1483-1486
LHRH release is dependent on the availability of calcium, and prostaglandin E2 is a potent releaser of LHRH. Therefore, we investigated the role of phospholipase A2 (PLA2) on the release of LHRH from the hypothalamus. Four rat hypothalami were perifused with Krebs-Ringer buffer, and after a 60-min preincubation period, PLA2 was applied during 10 min. The LHRH response was determined by RIA of 10-min fractions collected for the next 60 min. PLA2 induced LHRH release in a dose-related manner at amounts of 2, 10, and 50 U. Omission of Ca++ from the medium using EGTA eliminated the PLA2 effect. Indomethacin treatment increased rather than diminished the PLA2 stimulation. Perifusion with melittin, an activator of PLA2, also increased LHRH release. These results are interpreted as a demonstration that PLA2 has a role in the release of LHRH and that a different route of the cyclooxygenase may be involved besides the well known mediation of prostaglandin E2.  相似文献   
32.
In 24 cases of arrhythmogenic right ventricular (RV) dysplasia, the electrovectorcardiographic (ECG-VCG) behavior of T horizontal (wave and loop) was analyzed and the data compared with RV angiographic volumes. Arrhythmogenic RV dysplasia was diagnosed on the basis of echocardiographic and angiographic data in all subjects. At ECG, T wave was negative in V1 in nine subjects (37%), in V1-V2 in six (25%), in V1-V3 in two (8%), in V1-V4 in one (4%), in V1-V5 in two (8%), and in V1-V6 in four (16%). Nine subjects (37%) presented a bifid T wave in V2-V4. At VCG, T horizontal loop showed three morphologic characteristics: (1) counterclockwise rotation with a mean axis range of +15 degrees to -10 degrees (average, +5 degrees); (2) a figure-eight pattern with a mean axis range of +10 degrees to -40 degrees (average, -17 degrees); and (3) clockwise rotation with a mean axis range of -40 degrees to -110 degrees (average, -70 degrees). T wave changes seem to be primary and independent from QRS changes. RV and diastolic volumes ranged from 100 to 320 m1/m2 (average, 169 +/- 69). The extension of T wave negativity on precordial leads has a direct relationship with RV enlargement (r = 0.89, p less than 0.01). T changes are probably caused by dislocation of the left ventricle backwards secondary to RV dilatation, asynchronous RV repolarization, or intraparietal RV conduction defects.  相似文献   
33.
Obesity has been proposed to inflict a variety of stresses on adipose tissue, including inflammatory, metabolic, oxidative and endoplasmic reticulum stress. Through the activation of 'stress-sensing pathways', metabolic and endocrine alterations are produced, which probably contribute to the co-morbidities associated with obesity. Here, we review the evidence supporting the development of various obesity-related stresses and the activation of several stress-sensing pathways, specifically in adipocytes and/or adipose tissue, which manifest metabolic and endocrine dysfunction frequently in obesity. As the central role of adipose tissue in regulating whole-body metabolism is elucidated, understanding adipose tissue stress-sensing pathways might provide potential new therapeutic targets to attenuate obesity-related morbidity.  相似文献   
34.
We have investigated the possible ECG signs of incomplete Left Anterior Hemiblock (LAH). As an experimental model we chose the endocardial cushion defect, which is proved to have a ventricular activation correspondent to different degrees of LAH due to the particular disposition of the AV node and the His bundle. The VCG of 50 patients with endocardial cushion defect were divided into 5 groups according to the entity of the left and superior deviation of the maximum left vector. Comparison with the ECG signs shows that: a) minimal degrees of LAH occur with simple counterclockwise rotation of the frontal loop without a significant left axis deviation; b) there is no linear correlation between the importance of the left axis deviation and the signs of left ventricular activation asincronism. We conclude that, with the exception of this particular congenital heart disease, minimal LAH degrees can only be suspected on the basis of a counterclockwise VCG frontal loop, because the ECG diagnosis is possible only when the left axis deviation becomes important.  相似文献   
35.
36.
BackgroundThe development of allo-anti-Rh17 (anti-Hr0) in a −D– phenotype whose red blood cells (RBCs) lack CcEe antigens is most likely triggered by transfusion, transplantation, or pregnancy. Gene conversion is the predominating factor in generating RHD-CE-D and RHCE-D-CE hybrids like −D–.MethodsWe report here immunohematological and obstetrical data from 2 of the 5 pregnancies of a 24-year-old woman presenting with the −D– phenotype with anti-Rh17. Blood group typing, antibody screening, antibody differentiation, direct antiglobulin test (DAT), and antibody titers were performed by routine gel technology and tube testing. Additionally, molecular genetic analysis was performed. Fetal surveillance was done by sonographic evaluation of the fetal middle cerebral artery peak systolic velocity (MCA-PSV).ResultsBlood group typing showed O, C-c-D+E-e- and the DAT was negative. DNA sequencing revealed homozygosity for an RHCE-D(3–9)-CE null allele. Anti-Rh17 titers in the fourth pregnancy remained between 1:8 and 1:128, and no signs for a fetal anemia were observed. However, in the fifth pregnancy, the antibody titers increased up to 1:4,096. Signs of moderate fetal anemia were detected and cesarean section was performed at 34 + 6 weeks of gestation. The newborn presented with hemolytic anemia (cord blood hemoglobin [Hb] = 8.5 mg/dL). She received 2 compatible (small) packed RBC concentrates, phototherapy, and intravenous immunoglobulins.ConclusionOur case shows that the risk for hemolytic complications increases with the number of pregnancies of sensitized women. Only people who also lack CcEe antigens are compatible as donors. The role of such rare donors as lifesavers, their freedom, and voluntariness conflict with the urgent need for compatible blood.  相似文献   
37.
38.
39.
Recent theories emphasize the dynamic aspects of emotions. However, the physiological measures and the methodological approaches that can capture the dynamics of emotions are underdeveloped. In the current study, we investigated whether moment‐to‐moment changes in autonomic nervous system (ANS) activity are reliably associated with the unfolding of emotional experience. We obtained cardiovascular and electrodermal signals from participants while they viewed emotional movies. We found that the ANS signals were temporally aligned across individuals, indicating a reliable stimulus‐driven response. The degree of response reliability was associated with the emotional time line of the movie. Finally, individual differences in ANS response reliability were strongly correlated with the subjective emotional responses. The current research offers a methodological approach for studying physiological responses during dynamic emotional situations.  相似文献   
40.
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers because of late symptoms and resistance to chemotherapy and radiation therapy. We have investigated the appearance of c-kit, a stem cell marker, in both normal adult pancreatic tissue and in cancerous tissue. Apart from some very pale staining of islets of Langerhans, normal pancreas was devoid of staining with antibodies to c-kit. In contrast, in cancerous tissue that still preserves the overall integrity of the pancreatic tissue, there was a clear labeling in islets of Langerhans, which seemed to be co-localized with insulin containing β cells. In other cases, where the pancreatic tissue was completely deteriorated, intensive labeling was clearly evident in remnants of both the exocrine and the endocrine tissues. The duct cells of the adenocarcinoma were moderately but clearly labeled with antibodies to c-kit. In contrast, in metastasis of PDAC, very intensive labeling of c-kit was evident. The location of KRAS, which is strongly associated with PDAC, was also analyzed at the initial stages of the disease, when islets of Langerhans still preserve their integrity to a large extent. KRAS was found exclusively in islets of Langerhans and overlapped in its location with insulin and c-kit expressing cells. It is suggested that the modulation of the expression of c-kit, visualized by antibodies to the oncogene molecule, may play an important role in the formation and progression of PDAC. The absence of c-kit in normal pancreas and its appearance in PDAC is probably due to a mutational event, which probably allows conversion of the β cells into cancer stem cells (CSC). Co-expression of both c-kit and KRAS, typical markers for CSC with overlapping with insulin in islets of Langerhans, strongly support the notion that β-cells play a central role in the development of PDAC. The use of specific drugs that can attenuate the kinase activity of c-kit or target KRAS expressing cancer cells should be tested in order to attenuate the progression of this lethal disease.  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