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   1014篇
  免费   47篇
  国内免费   9篇
医药卫生   1070篇
  2023年   2篇
  2022年   12篇
  2021年   32篇
  2020年   32篇
  2019年   25篇
  2018年   39篇
  2017年   23篇
  2016年   20篇
  2015年   30篇
  2014年   42篇
  2013年   51篇
  2012年   78篇
  2011年   80篇
  2010年   49篇
  2009年   24篇
  2008年   65篇
  2007年   53篇
  2006年   52篇
  2005年   55篇
  2004年   37篇
  2003年   29篇
  2002年   39篇
  2001年   21篇
  2000年   23篇
  1999年   24篇
  1998年   6篇
  1997年   7篇
  1996年   8篇
  1994年   5篇
  1993年   3篇
  1992年   10篇
  1991年   15篇
  1990年   6篇
  1989年   9篇
  1988年   6篇
  1987年   8篇
  1986年   5篇
  1985年   6篇
  1984年   6篇
  1981年   3篇
  1979年   4篇
  1978年   3篇
  1972年   1篇
  1971年   2篇
  1970年   2篇
  1969年   2篇
  1968年   5篇
  1967年   2篇
  1966年   2篇
  1964年   2篇
排序方式: 共有1070条查询结果,搜索用时 15 毫秒
1.
2.
Bone mineral density of the lumbar spine in women with endometriosis   总被引:2,自引:1,他引:1  
Young women with endometriosis have reduced cortical and trabecular bone mineral density of the wrist compared with age-matched controls. This conclusion was based on 41 subjects from one geographical location. The purpose of this study was to test this finding in a larger, more geographically diverse population. One hundred women with laparoscopically proven endometriosis were enrolled in this study for the evaluation of the efficacy of nafarelin, a gonadotropin-releasing hormone agonist. Patients were recruited from nine investigators across the United States and Canada, and bone mineral density of the lumbar spine was obtained at baseline, with 6 Hologic QDR (Hologic Inc., Waltham, MA) and a Lunar DPX (Lunar Radiation Corp., Madison, WI) instrument. The age of the women was 30.3 +/- 5.8 years (mean +/- SD); 91% were white. Bone mineral density of the lumbar spine was 1.1 +/- 0.11 g/cm2 (n = 85 Hologic QDR) and 1.2 +/- 0.93 g/cm2 (n = 15 Lunar DPX). Hologic bone mineral density was 104.8 +/- 11.0 and Lunar bone mineral density was 103.4% +/- 7.8% of normal values for age. To conclude, in a population based cross-sectional study of patients with endometriosis, we do not observe low bone mineral density of the lumbar spine by techniques that measure a combination of cortical and trabecular bone.  相似文献   
3.
A new technique of choledochoenterostomy was devised to solve some of the problems of enterobiliary anastomosis with a normal calibre. The distal extremity of the common bile duct is completely surrounded by the bowel mucosa to a length of 3 cm after seromyectomy of a bowel wall rectangle of 4 × 1 cm. Experimental studies in rats and dogs demonstrated that this procedure prevents the risks of anastomotic disruption and functions like a mechanical unidirectional valve, which has great efficacy in stopping enterobiliary reflux. Studies in ten patients with obstructive jaundice with an extrahepatic biliary dilation less than 1.2 cm diameter submitted to this procedure Confirmed the experimental results. All patients were asymptomatic, without jaundice and with normalization of the liver enzymes after 2 months. The permeability of the valvular anastomosis studied by cholangiography, the HIDA 99mTc test and manometry was quite similar to other classical biliary-enteric anastomosis. In contrast, anti-reflux efficacy was only demonstrated in patients with a valvular anastomosis.  相似文献   
4.
5.
OBJECTIVE: The 5-year project in the province of Sofala was designed to improve access, quality and utilization of emergency obstetric care (EmOC) by strengthening rural hospitals and health centers and ultimately the health system's capacity to respond to emergencies more quickly and effectively. METHODS: Implementation consisted of attention to infrastructure, human resource development, transportation and communication systems, and management. Specific management aspects that were targeted for improvement included: supportive supervision, logistics for supplies, equipment and drugs, record keeping, monitoring and evaluation, and quality improvement techniques such as maternal death audits. RESULTS: Access to EmOC improved with an increase in the number of fully functional EmOC facilities from 4 to 18. The number of women with obstetric complications who were admitted for treatment in participating facilities tripled, and the proportion of those women dying declined by half. CONCLUSIONS: Close collaboration and partnership with the provincial health directorate make the sustainability of many results likely while the replication of much of the Sofala model to other provinces is promising for the national strategy to reduce maternal mortality.  相似文献   
6.
The R337H TP53 mutation is a low-penetrance molecular defect that predisposes to adrenocortical tumour (ACT) formation in Brazilian and possibly other populations. Additional genetic defects may be responsible for the variable expression of ACTs in these cases. The inhibin α-subunit gene (INHA) on 2q33-qter has been implicated in mouse adrenocortical tumourigenesis. We studied 46 pediatric patients with ACTs from Brazil for INHA genetic alterations; 39 of these patients were heterozygous carriers of the R337H TP53 mutation. We first mapped the INHA gene by radiation hybrid analysis and determined 10 linked microsatellite markers in an area flanked by D2S1371 and D2S206 on 2q33-qter. These markers were then used for loss of heterozygozity (LOH) studies in nine paired germline and tumour DNA samples. Mapping placed the INHA gene in close proximity to D2S2848 (SHGC11864) with a log of odds (LOD) score of 5.84. LOH for at least one marker in the region was identified in 8/9 tumours (89%). Six patients were heterozygous for three INHA mutations: one in exon 1, 127C>G, and two in exon 2, 3998G>A and 4088G>A, all leading to amino acid substitutions (P43A, G227R, and A257T, respectively). A257T is located in a conserved INHA region, highly homologous to transforming growth factor-ß; both G227R and A257T change polarity, and, in addition, G227R changes the pH. We conclude that these sequence alterations and the detected 2q allelic changes suggest that INHA may be one of the contributing factors needed for ACT formation in pediatric patient carriers of the R337H TP53 mutation.  相似文献   
7.
Abstract

The stethoscope is a major symbol of modern medicine. It is used for diagnosis of different conditions and enables physicians to listen to internal body sounds. Electrocardiography was only introduced in medicine in the beginning of the twentieth century. Today measuring heart’s electrical activity is also fundamental cardiac diseases diagnosis. Although performed with independent devices, requiring physician and patient presence in the same physical space, in combination they enhance cardiovascular assessment. In this paper, a digital stethoscope encapsulation was designed, adding new functionality to this advanced medical device. Today wired and wireless communications enable different medical devices to share data and information, over long distances. Using low-cost hardware technologies, the encapsulation will add the ability to acquire and transmit via Bluetooth the Electrocardiographic activity, determined in the same cardiac focus and synchronised with the Phonocardiographic sound recordings. Several encapsulation concepts were developed and prototyped using 3D printing. They were easily fitted to the digital stethoscope and tested in a hospital environment for ergonomics, acoustic and electric signals acquisition. The best concept was chosen with the help of a physician’s opinion and the final prototype performance was very satisfactory.  相似文献   
8.
The SRY gene (sex-determining region of the Y chromosome) initiates the process of male sex differentiation in mammalians. In humans mutations in the SRY gene have been reported to account for 10-15% of the XY sex reversal cases. We describe here two novel missense mutations in the SRY gene after the screening of 17 patients, including 3 siblings, with 46,XY gonadal dysgenesis and 4 true hermaphrodites. One of the mutations, an A to C transversion within the HMG box, causes the N65H substitution and it was found in a patient presenting 46,XY pure gonadal dysgenesis. The Escherichia coli expressed SRY(N65H) protein did not present DNA-binding activity in vitro. The other mutation, a G to T transversion, causes the R30I substitution. This mutation was found in affected and nonaffected members of a family, including the father, two siblings with partial gonadal dysgenesis, a phenotypic female with pure gonadal dysgenesis, and three nonaffected male siblings. The G to T base change was not found in the SRY sequence of 100 normal males screened by ASO-PCR. The R30I mutation is located upstream to the HMG box, within the (29)RRSSS(33) phosphorylation site. The E. coli expressed SRY(R30I) protein was poorly phosphorylated and consequently showed reduced DNA-binding capacity in vitro.  相似文献   
9.
10.
Central projections from peripheral sensory neurons segregate into distinct, ventrally positioned longitudinal tracts within the segmental ganglia of the leech Hirudo medicinalis. As documented here, there is an additional tract in the neuropils of the fifth and sixth body ganglia, located at the lateral margin and formed by afferent axons (the "sex afferents") originating from sensory neurons located in the male and female genitalia. Ablation of the genitalia results in the complete absence of this additional tract. We asked (1) whether segmental differences exist in the distribution of pathway cues available to the sex afferents, and (2) whether central pathway selection by these axons is specific. We transplanted the primordia of the male genitalia to several ectopic positions posterior to the sixth body segment and labeled the ectopic sex afferents in order to examine their paths in the CNS. In about 50% of the experimental animals, afferent axons originating in the transplanted tissue segregated into a distinct lateral fiber bundle within the neuropil of a nearby ganglion, in a position corresponding to their normal one in the sex ganglia. The sex afferents therefore find their normal pathways even in the ganglia of inappropriate segments, although these pathways are not used by any other afferents in these ganglia. We propose, therefore, that the positional cues employed by afferent axons to select appropriate pathways in the ganglionic neuropil are expressed in all segments of the leech CNS, regardless of whether such cues are normally used by afferent axons in each segment.  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