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   7849篇
  免费   368篇
  国内免费   126篇
耳鼻咽喉   20篇
儿科学   390篇
妇产科学   298篇
基础医学   979篇
口腔科学   120篇
临床医学   643篇
内科学   899篇
皮肤病学   208篇
神经病学   941篇
特种医学   117篇
外国民族医学   2篇
外科学   664篇
综合类   1029篇
预防医学   336篇
眼科学   127篇
药学   576篇
  1篇
中国医学   127篇
肿瘤学   866篇
  2024年   9篇
  2023年   53篇
  2022年   72篇
  2021年   166篇
  2020年   100篇
  2019年   547篇
  2018年   448篇
  2017年   289篇
  2016年   200篇
  2015年   160篇
  2014年   327篇
  2013年   295篇
  2012年   365篇
  2011年   413篇
  2010年   387篇
  2009年   344篇
  2008年   322篇
  2007年   328篇
  2006年   260篇
  2005年   202篇
  2004年   176篇
  2003年   169篇
  2002年   170篇
  2001年   122篇
  2000年   89篇
  1999年   84篇
  1998年   62篇
  1997年   72篇
  1996年   64篇
  1995年   50篇
  1994年   51篇
  1993年   29篇
  1992年   33篇
  1991年   34篇
  1990年   25篇
  1989年   21篇
  1988年   15篇
  1987年   13篇
  1986年   14篇
  1985年   205篇
  1984年   359篇
  1983年   192篇
  1982年   207篇
  1981年   249篇
  1980年   150篇
  1979年   172篇
  1978年   96篇
  1977年   78篇
  1976年   35篇
  1975年   10篇
排序方式: 共有8343条查询结果,搜索用时 15 毫秒
11.
12.
外阴尖锐湿疣人乳头瘤病毒感染的检测与分型   总被引:2,自引:0,他引:2  
目的 了解患外阴尖锐湿疣人乳头瘤病毒(HPV)6型和11型的感染情况及PCR方法对尖锐湿疣诊断与分型的临床意义。方法 采用PCR方法测定160例尖锐湿疣患病题组织或分泌物中HPV6/11型及HPVl6/18型的感染率。结果 HPV6/11型感染率为95%(152/160),HPVl6/18型感染率为5%(8/160),HPV6/11型 HPVl6/18型混合感染率为1.3%(2/160)。结论 外阴尖锐湿疣患以HPV6型和11型感染为主。PCR方法是一种比较适合临床HPV检测与分型的极为敏感和特异的诊断方法。  相似文献   
13.
Encephalopathy is a common complication of sepsis. However, little is known about the morphological changes that occur in the brain during sepsis. In this study, fecal peritonitis was induced in Wistar rats, which had been monitored for 4 h before their brains were removed and samples from the CA1 area taken. In addition to higher blood pressure with a decreasing pattern and a significant drop in rectal temperature, an increased heart rate and marked respiratory failure were observed. The tissue was investigated and compared with corresponding hippocampal samples taken from sham‐operated and not operated control groups. Significantly more peri‐microvascular edema was found in the hippocampal CA1 area in the septic group. The percentages of the peri‐microvascular edema were 158.57 ± 3.6%, 122.84 ± 1.5% and 120.24 ± 1.9% in the fecal peritonitis group, sham‐operated and not operated control groups, respectively. The results may suggest that the edema observed around the microvessels may participate in the pathogenesis of the septic encephalopathy probably by causing in the microvascular permeability characteristics.  相似文献   
14.
15.
目的 探讨对CA的最佳治疗方案及有效护理措施.方法 采取二氧化碳激光联合重组人白介素100万u局部疣体基地部注射和20万u臀部皮下注射治疗CA,根据病人实际情况给予一般性病护理措施、支持性心理治疗和健康教育.结果 675例CA患者386例一次性治愈,137例二次治愈,71例三次治愈,27例三次以上治愈,54例失访,总治愈率为92.0%,三个月后复发106例,复发率为17.1%.结论 采用本法治疗CA是一种简便、安全、不留疤痕、行之有效的方法.  相似文献   
16.
Effects of nilvadipine on the low- and high-voltage activated Ca2+ currents (LVA and HVA ICa, respectively) were compared with other organic Ca2+ antagonists in acutely dissociated rat hippocampal CA1 pyramidal neurons. The inhibitory effects of nilvadipine, amlodipine and flunarizine on LVA ICa were concentration- and use-dependent. The apparent half-maximum inhibitory concentrations (IC50s) at every 1- and 30-s stimulation were 6.3×10−7 M and 1.8×10−6 M for flunarizine, 1.9×10−6 M and 7.6×10−6 M for nilvadipine, and 4.0×10−6 M and 8.0×10−6 M for amlodipine, respectively. Thus, the strength of the use-dependence was in the sequence of nilvadipine>flunarizine>amlodipine. Nilvadipine also inhibited the HVA ICa in a concentration-dependent manner with an IC50 of 1.5×10−7 M. The hippocampal CA1 neurons were observed to have five pharmacologically distinct HVA Ca2+ channel subtypes consisting of L-, N-, P-, Q- and R-types. Nilvadipine selectively inhibited the L-type Ca2+ channel current which comprised 34% of the total HVA ICa. On the other hand, amlodipine non-selectively inhibited the HVA Ca2+ channel subtypes. These results suggest that the inhibitory effect of nilvadipine on the neuronal Ca2+ influx through both LVA and HVA L-type Ca2+ channels, in combination with the cerebral vasodilatory action, may prevent neuronal damage during ischemia.  相似文献   
17.
In the CA1 region of hippocampal slices prepared from young adult rats, we studied the ability of several specific agonists of metabotropic glutamate receptors (mGluRs) to depress excitatory synaptic transmission at the CA3–CA1 pyramidal cell synapses. Three groups of mGluRs have been described: group 1 (mGluR1 and 5) receptors are positively coupled to phospholipase C whereas group 2 (mGluR2 and 3) and group 3 (mGluR4, 6, 7 and 8) receptors are negatively coupled to adenylate cyclase. We found that the broad-spectrum agonist (1 S ,3R)-1-aminocyclopentyl-1,3-dicarboxylate and the group 1-specific agonist ( R,S )-dihydroxyphenylglycine both reversibly inhibited evoked field excitatory postsynaptic potentials, indicating the involvement of group 1 mGluRs. ( R,S )-3,5-dihydroxyphenylglycine presumably inhibited transmission via a presynaptic mechanism, as whole-cell voltage-clamp recordings revealed that inhibition of the synaptic transmission was always accompanied with an increase in paired-pulse facilitation. Treatment with a specific blocker of mGluR1 receptors, the phenylglycine derivative ( S )-4-carboxyphenylglycine, was without effect on the (1 S ,3 R )-1-amino-cyclopentyl-1,3-dicarboxylate-induced depression of the field excitatory postsynaptic potentials, strongly suggesting that mGluR5 receptors are responsible for the (1 S ,3 R )-1-aminocyclopentyl-1,3-dicarboxylate effect. Two selective agonists of group 2 mGluRs, (2 S ,1' s ,2' s )-2-(2'-carboxycyclopropyl)glycine and 4-carboxy-3-hydroxyphenylglycine, were totally ineffective in blocking CA3-CA1-evoked synaptic transmission, excluding the involvement of mGluR2/3 subtypes at this developmental stage.  相似文献   
18.
The studies presented in this article demonstrate the release of an IgE-dependent chemotactic factor for polymorphonuclear neutrophils (PMN) and eosinophils by alveolar macrophages (AMs) from normal subjects (n = 15) and allergic asthmatic patients (n = 15). A 60-minute incubation of normal AMs previously sensitized by 20% nonheated allergic sera with anti-human IgE antibody or the related allergen induced the release of a chemotactic activity (CA) for PMN and eosinophils in culture supernatants. When AMs were obtained from asthmatic patients, direct incubation with anti-IgE or the related allergen induced the same CA, whereas incubation with an unrelated allergen failed to produce CA (neutrophil CA after addition of anti-IgE, 22.5 +/- 3.5 cells per high power field; with related allergen, 15.8 +/- 3.6; with unrelated allergen, 0.7 +/- 1.8; p less than 0.0001). A partial characterization of the neutrophil chemotactic factor was carried out. Enzymatic treatment by trypsin or carboxypeptidase or by heating (56 degrees C for 3 hr) failed to abolish the neutrophil CA. After gel filtration the greater part of the neutrophil CA (80%) was recovered among low-molecular-weight components (300 to 1300 daltons). A preliminary deactivation of PMN by leukotriene B4 suppressed the CA of AM supernatants. These results indicate that IgE-dependent stimulation of AMs produces a neutrophil and eosinophil CA, present in a low-molecular-weight fraction possibly related to leukotrienes, and emphasizes the role of AMs in inflammatory lung processes during allergic asthma.  相似文献   
19.
The study objectives were to compare in vitro transportability and physical properties of respiratory mucus, obtained invasively by direct collection (DC) right after endotracheal intubation and non-invasively by sputum induction with 3% hypertonic saline solution inhalation (SI) 24 h before the anesthesia. Twenty-two patients with no pulmonary disease scheduled for elective abdominal surgical procedures were studied. The parameters analyzed and the main results are as follows. (1) Transportability by cilia (MCT), SI was higher than DC (0.94+/-0.25 and 0.62+/-0.25; P<0.001). There was a significant correlation between the two methods and DC could be estimated by: DC=0.21+(0.44 SI) (r=0.44; P<0.001). (2) Transportability by cough (CC), SI was higher than DC (68.23+/-32.1 and 33.58+/-19.04 mm; P=0.002). (3) Contact angle (CA), SI was lower than DC (10+/-3 degrees and 22+/-14 degrees ; P=0.025). (4) Rheological properties (no significant difference obtained between SI and DC). These results indicated that SI changes mucus physical properties and transportability in non-expectorators.  相似文献   
20.
卢志贤 《中国微循环》2008,12(5):305-306
目的探讨血清sE—cad、CA724、CA199联合检测在胃癌诊断中的价值。方法应用酶联免疫吸附法(ELISA)技术检N30例正常对照组、35例良性胃病、45例胃癌患者血清sE—cad的含量,CA724和CA199则采用电化学发光技术检测。结果胃癌患者血清sE—cad、CA724和CA199的含量明显高于正常对照组和良性胃病组,差异有显著性(P〈0.01),三者联合检测敏感性、准确性均显著提高(P〈0.05)。结论血清sE—cad、CA724和CA199联合检测有助于提高胃癌诊断的敏感性和特异性。  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