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   40447篇
  免费   1837篇
  国内免费   216篇
耳鼻咽喉   400篇
儿科学   903篇
妇产科学   513篇
基础医学   4998篇
口腔科学   1013篇
临床医学   2558篇
内科学   10929篇
皮肤病学   841篇
神经病学   2848篇
特种医学   1307篇
外科学   7059篇
综合类   187篇
一般理论   3篇
预防医学   1227篇
眼科学   478篇
药学   2674篇
中国医学   144篇
肿瘤学   4418篇
  2023年   232篇
  2022年   384篇
  2021年   705篇
  2020年   372篇
  2019年   526篇
  2018年   688篇
  2017年   575篇
  2016年   646篇
  2015年   661篇
  2014年   913篇
  2013年   1095篇
  2012年   1800篇
  2011年   1922篇
  2010年   1132篇
  2009年   958篇
  2008年   1892篇
  2007年   2074篇
  2006年   2023篇
  2005年   2171篇
  2004年   2093篇
  2003年   2101篇
  2002年   1978篇
  2001年   1288篇
  2000年   1343篇
  1999年   1221篇
  1998年   576篇
  1997年   410篇
  1996年   434篇
  1995年   409篇
  1994年   355篇
  1993年   329篇
  1992年   853篇
  1991年   791篇
  1990年   728篇
  1989年   790篇
  1988年   696篇
  1987年   640篇
  1986年   574篇
  1985年   567篇
  1984年   394篇
  1983年   323篇
  1982年   177篇
  1979年   291篇
  1978年   201篇
  1977年   173篇
  1974年   163篇
  1973年   177篇
  1972年   172篇
  1971年   159篇
  1970年   161篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
L  zl  L  n  rd  Yutaka Oomura  Yasuhiko Nakano  Shuji Aou  Hitoo Nishino 《Brain research》1989,500(1-2):359-368
Single neuron activity in the monkey amygdala was investigated during cue signalled conditioned bar press feeding behavior and the effects of electrophoretically applied acetylcholine (ACh) and atropine were analyzed. ACh increased the firing rate of one third of the neurons tested; these excitatory responses were inhibited by the muscarinic receptor antagonist atropine. No characteristic location of ACh-sensitive neurons was found, cells were diffusely distributed throughout the amygdala. Activity of ACh-sensitive neurons did not correlate with any particular event during the bar press feeding task. However, continuous application of ACh at low current intensity during the task significantly enhanced the task-related excitatory firing patterns, or markedly attenuated the inhibitory responses. Continuous application of atropine elicited or enhanced inhibitory response patterns. These results suggest that the cholinergic system of the monkey amygdala facilitates neuronal excitation but attenuates inhibition related to various phases of feeding behavior, such as to cue recognition, food aquisition and rewarding process.  相似文献   
73.
Spontaneous peripelvic extravasation must be distinguished from spontaneous rupture of the renal pelvis in urological emergency. The literatures revealed 42 cases of peripelvic extravasation and 35 cases of rupture of the renal pelvis in Japan. Most of them were caused by urolithiasis and malignant tumors. We report 2 cases of spontaneous peripelvic extravasation caused by urolithiasis, which were successfully treated conservatively.  相似文献   
74.
Serum myoglobin levels have been found to be elevated for a few hours after removal of a tourniquet. In the present study, levels of serum myoglobin were measured by radioimmunoassay from local blood samples in patients who were treated with surgery of the hand in a bloodless field. After removal of the tourniquet blood samples were obtained from the antecubital vein of each patient immediately after release, five minutes, one hour, and 24 hours later. In these samples the serum myoglobin levels were not influenced by the mode of anesthesia, tourniquet time, or specific type of surgery. When the upper extremity was cooled with ice water before application of the tourniquet, however, the increase of serum myoglobin was statistically significantly inhibited when compared with the normothermic condition. Muscle injury due to tourniquet ischemia may be decreased by cooling of the upper extremity prior to tourniquet application.  相似文献   
75.
76.
Activity labeling was applied to the olfactory systems of the terrestrial slug Limax valentianus using 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescent derivative of glucose. 2-NBDG was incorporated into cultured Limax olfactory interneurons, and this was partially blocked by the presence of a high concentration of glucose in the medium, indicating that a part of the uptake of 2-NBDG is mediated by glucose transporters. Next, in order to map odor-related neuronal activity in the primary olfactory center, tentacular ganglion, we injected 2-NBDG into the body cavities of slugs and exposed them to odors or clean air (control). In the odor-stimulated animals, the cell mass region was strongly stained. The digit-like extensions and the neuropil region were also stained in some animals. The control animals showed no staining. The neurons in the cell mass are thought to be involved in generating oscillating activities in the tentacular ganglion, and their activation may imply modulation of oscillatory activity during odor processing. Our results show that 2-NBDG is useful for mapping neuronal activity in vivo.  相似文献   
77.
78.
Summary We observed a rare cerebrovascular anomaly in a patient with brain-stem infarction. Two right vertebral arteries arose from the subclavian artery and communicated directly with each other under the transverse foramen of the fourth cervical vertebra. The left vertebral artery consisted of a rudimentary artery that arose from the left subclavian artery, ran through the transverse foramen of the sixth cervical vertebra and then tapered down to disappear at the fourth/fifth cervical vertebrae, plus a second, accessory artery that arose from a branch of the left thyrocervical trunk, ran through the transverse foramen of the fifth cervical vertebra and tapered off to disappear at the first/second cervical vertebrae.  相似文献   
79.
Four patients with viscero-atrial heterotaxic syndrome underwent a right heart bypass operation. 2 patients had right isomerism, and two had left isomerism. 3 patients had common atrio-ventricular canal, three had double outlet right ventricle, one had mitral valve hypoplasia, and one had double inlet right ventricle. All patients had anomalous systemic or pulmonary venous drainage. Redirection of systemic venous drainage was accomplished by total cavo-pulmonary shunt (TCPS) (2 patients), atrial baffle (1 patient), and intraatrial conduit (1 patient). In one patient underwent TCPS, regurgitant common atrioventricular valve was replaced with a prosthetic valve. One who had total anomalous pulmonary venous drainage (type Ib) died after cardiac repair. The three survivors are in improved condition. The right heart bypass operation, like total cavopulmonary shunt or connection, simplifies the redirection of systemic venous drainage and offers improved results in the surgical treatment of complex cardiovascular anomalies with viscero-atrial heterotaxic syndrome.  相似文献   
80.
Various kinds of chemical mediators have been implicated in the pathogenesis of bronchial asthma. PGD2 is a cyclooxygenase product which has various physiological effects. In this experimental study, we investigated the role of PGD2 in the pathogenesis of bronchial asthma. In a bioassay system, PGD2 caused dose-dependent contractile responses in non-sensitized guinea pig trachea and lung tissue strips. The subthreshold concentration of PGD2 in both strips was 25 ng/ml. Acetylcholine-induced contractile responses in both strips were significantly increased by continuous infusion of PGD2. In the experimental model of bronchial asthma, the levels of PGD2 were significantly increased in serum, bronchoalveolar lavage fluid (BALF) and lung tissue of sensitized guinea pigs after antigen challenge. We have also reported that the levels of PGD2 in BALF were elevated in patients with stable state bronchial asthma. These results suggest that PGD2 may be a key substance that increases airway responsiveness and induces asthmatic attacks.  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