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   18195篇
  免费   1464篇
  国内免费   340篇
耳鼻咽喉   119篇
儿科学   1523篇
妇产科学   972篇
基础医学   1524篇
口腔科学   179篇
临床医学   1755篇
内科学   2408篇
皮肤病学   109篇
神经病学   892篇
特种医学   367篇
外科学   1993篇
综合类   1928篇
一般理论   1篇
预防医学   3250篇
眼科学   140篇
药学   1824篇
  5篇
中国医学   474篇
肿瘤学   536篇
  2024年   47篇
  2023年   340篇
  2022年   574篇
  2021年   837篇
  2020年   654篇
  2019年   747篇
  2018年   663篇
  2017年   707篇
  2016年   653篇
  2015年   640篇
  2014年   1168篇
  2013年   1480篇
  2012年   963篇
  2011年   1098篇
  2010年   878篇
  2009年   823篇
  2008年   921篇
  2007年   862篇
  2006年   695篇
  2005年   631篇
  2004年   532篇
  2003年   495篇
  2002年   388篇
  2001年   325篇
  2000年   282篇
  1999年   236篇
  1998年   199篇
  1997年   161篇
  1996年   151篇
  1995年   130篇
  1994年   139篇
  1993年   115篇
  1992年   117篇
  1991年   101篇
  1990年   96篇
  1989年   70篇
  1988年   82篇
  1987年   68篇
  1986年   78篇
  1985年   125篇
  1984年   111篇
  1983年   86篇
  1982年   79篇
  1981年   74篇
  1980年   73篇
  1979年   63篇
  1978年   58篇
  1977年   34篇
  1976年   39篇
  1973年   24篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Rats that were neonatally sympathectomized with guanethidine (GUA) and given access to a four-component supermarket diet (SD) when either adolescent or adult gained weight at the same rate as controls. Adrenodemedullation (MDL) of adults, either alone or in combination with GUA treatment, also failed to influence the development of dietary obesity. Neonatal sympathectomy induced small changes in caloric consumption and diet preferences. These results question the notion that the sympathetic nervous system (SNS) is an essential contributor to the control of body weight and the development of dietary obesity.  相似文献   
122.
This paper reviews the investigations of Prof. L. V. Krushinsky and his colleagues into the genetics of complex behaviors in mammals. The ability of animals to extrapolate the direction of a food stimulus movement was investigated in wild and domesticated foxes (including different fur-color mutants), wild brown rats, and laboratory rats and mice. Wild animals (raised in the laboratory) were shown to be superior to their respective domesticated forms on performance of the extrapolation task, especially in their scores for the first presentation, in which no previous experience could be used. Laboratory rats and mice demonstrated a low level of extrapolation performance. This means that only a few laboratory animals were capable of solving the task, i.e., the percentage of correct solutions was equivalent to chance. The brain weight selection program resulted in two mice strains with a 20% (90-mg) difference in brain weight. Ability to solve the extrapolation task was present in low-brain weight mice in generations 7–11 but declined with further selection. Investigation of extrapolation ability in mice with different chromosomal anomalies demonstrated that animals with Robertsonian translocations Rb(8,17) 1lem and Rb(8,17) 6Sic were capable of solving this task in a statistically significant majority of cases, while mice with fusion of other chromosomes, as well as CBA normal karyotype mice, performed no better than expected by chance. Mice with two types of partial trisomies and animals homo- and heterozygous for translocations were also tested. Although mice with T6 trisomy performed no better than expected by chance, animals with trisomy for a chromosome 17 fragment solved the task successfully. Thus, a genetic component underlying the ability to solve the extrapolation task was demonstrated in three animal species. The extrapolation task in animals is considered to reveal a general capacity for elementary reasoning. The genetic basis of this capacity is very complex.  相似文献   
123.
Purification of bovine conglutinin using pepsin digestion   总被引:6,自引:0,他引:6  
This paper describes a new method for the purification of bovine conglutinin based on the relative resistance of this protein to pepsin digestion. First, conglutinin is purified by absorption on yeast, then the preparation is treated with 2% pepsin (w/w) at 4°C for 18 hr, and finally gel filtrated on agarose A5m. The yield is 60–75% and conglutinin thus prepared appears physically, immunochemically and functionally intact. This procedure allows for a rapid production of sufficient amounts of conglutinin for immune complex detection or purification methods.  相似文献   
124.
The Eurotransplant (ET) allocation algorithm, newly implemented in 2000, gives priority for heart transplantation (HTx) to patients with high urgency (HU) status, but now this status is rescinded upon ventricular assist device (VAD) implantation and only regained if severe complications occur during mechanical circulatory support (MCS). We studied the effects of this change on the patients in our institute who were waiting for HTx with MCS. The median duration of MCS until HTx in adult patients gradually increased from 3.1 months in 1994, reaching a peak of 16.7 months in 2000, and then gradually decreased to 6.0 months in 2003. Among the patients with VAD implantation as a bridge to HTx, two patients were on MCS for more than 1 year (the longest duration of MCS being 1.6 years) at the end of 1999, and this figure increased to nine patients and a maximum MCS duration of 3.7 years at the end of 2003. These data imply that the patients in whom a complication occurred in the early phase of MCS and who had overcome this complication underwent HTx early with HU status, and those who were stable during MCS waited a long time for HTx. Furthermore, the number of patients in the latter group is increasing. The new allocation algorithm imposes on patients with MCS waiting for HTx who are relatively young and free from complications and serious coexisting disease, very long-term MCS without an end to VAD bridging, which is almost equivalent to destination therapy. Part of this paper was presented at the 42nd JSAO Conference (Tokyo, October 5–7, 2004)  相似文献   
125.
胎儿脏器重量的测量   总被引:3,自引:1,他引:3  
尸检测量了600例4-10月龄新鲜国人胎儿的脑、心脏、肺脏、脾脏、肾脏、肝脏、胰腺、胃、胸腺、肾上腺、甲状腺、睾丸、卵巢子宫等十三项脏器的重量并分别对胎龄作半对数图以观察各脏器生长发育速度变化的趋势。结果表明所有脏器重量均随胎龄以不同速度增加,存在着三种速度变化类型:(1)稳定型,该型脏器于整个胎儿期生长发育速度保持相对稳定;(2)先慢后快型,该型脏器以六月龄前、后生长发育速度显著不同为特征;(3)末期速降型,该型脏器的生长发育速度变化与先慢后快型相似,但九月龄之后发育速度显著降低。  相似文献   
126.
目的:脑康复冲剂临床用于治疗脑血栓血瘀证患者,本实验观察其对在大鼠实验性软脑膜微循环障碍的影响。方法:大鼠预防性给药,用高分子右旋糖酐水溶液静脉注射形成大鼠软脑膜的微循环障碍,观察脑康复冲剂对大鼠微循环的影响。结果:用高分子右旋糖酐造模后,大鼠软脑膜的微循环发生障碍,表现为血液流速减慢、血细胞聚集等,脑康复冲剂组血流速度开始减慢的时间明显比生理盐水对照组延长,且分级数也明显优于生理盐水组,对高分子右旋糖酐造成的血液流态障碍,脑康复组明显好于生理盐水组(P<0.05),毛细血管网交叉点数开始减少的时间也比生理盐水对照组延长,差异显著(P<0.01)。结论:脑康复冲剂使大鼠血流速度和血液流态得到改善,具有预防和改善动物脑微循环障碍的作用。  相似文献   
127.
目的通过对57例妊娠分别使用二维、三维超声测量相关参数估计胎重,并作统计学比较,从而评价三维超声对于估测胎儿体重、诊断胎儿发育迟缓及巨大胎的优势和价值。方法对2005年10月至2006年3月间在我院分娩的57例妊娠,研究组用三维超声测胎儿股容积估计胎重,对照组用二维超声同步测量相关参数估计胎重。结果对两组估重结果与胎儿实际出生体重作相关统计学分析,研究组相关系数为0.983,对照组为0.906(P〈0.05),前者与实际体重关系更密切。结论三维超声测量胎儿股容积估测胎儿体重,较传统二维超声具有更大优势,对于发现胎儿发育迟缓(FGR)及巨大胎意义重大,有利于指导临床冶疗、选择分娩方式。  相似文献   
128.
The spleen may be preserved during distal pancreatectomy (DP) for benign disease. The aim of this study was to compare the perioperative and postoperative courses of patients with conventional DP and spleen-preserving distal pancreatectomy (SPDP) for benign lesions or tumors with low-grade malignant potential occurred at the body or tail of the pancreas. A retrospective analysis was performed for the hospital records of all the patients undergoing DP and SPDP between January 1995 and April 2006. One-hundred forty-three patients underwent DP and 37 patients underwent SPDP. There were no significant differences in age, sex, indications of operation, estimated blood loss, operative time, and postoperative hospital stay between the two groups. Pancreatic fistula occurred in 21 (13.3%) patients following DP and in 3 (8.1%) following SPDP without a significant difference (p=0.081). Portal vein thrombosis occurred in 4 patients after DP. Splenic infarction occurred in one patient after SPDP. Overwhelming postosplenectomy infection was observed in one patient after DP. SPDP can be achieved with no increase in complication rate, operative time, or length of postoperative hospitalization as compared to conventional DP. Additionally, it has the advantage of reducing the risk of overwhelming postsplenectomy infection and postoperative venous thrombosis.  相似文献   
129.
An automated method was used to record the temporal pattern of feeding of lines of mice selected over 15 generations for high and low body weight (L-mice and S-mice, respectively). Both L-mice and S-mice eat in meals concentrated during the night, and meal frequency is similar in the two lines, but L-mice consume much larger meals, each made up of many more separate feeding bouts. The outbred strain from which the selected lines were derived has a similar basic pattern of feeding in meals, which becomes like that of L-mice when the animal's thermogenic metabolic rate is high, and like that of S-mice when it is low, suggesting that the differences between the feeding patterns of the two selected lines are a secondary consequence of alterations in whole body metabolic rate.  相似文献   
130.
采用柱上聚合的方法制备血红蛋白溶液,解决传统血红蛋白聚合过程中由于戊二醛的活性过高导致平均分子量大、产物分子量分布宽的问题。该方法利用阳离子交换剂对修饰度(聚合度)小的血红蛋白吸附能力大的原理,使其在柱上富积,同时加入戊二醛进行聚合反应。结果表明该方法能比较有效地缩小聚合血红蛋白的分子量分布。  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