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   2806篇
  免费   110篇
  国内免费   11篇
耳鼻咽喉   87篇
儿科学   93篇
妇产科学   140篇
基础医学   380篇
口腔科学   48篇
临床医学   163篇
内科学   664篇
皮肤病学   44篇
神经病学   289篇
特种医学   47篇
外科学   183篇
综合类   17篇
预防医学   209篇
眼科学   67篇
药学   325篇
中国医学   3篇
肿瘤学   168篇
  2023年   9篇
  2022年   83篇
  2021年   134篇
  2020年   44篇
  2019年   72篇
  2018年   65篇
  2017年   62篇
  2016年   70篇
  2015年   88篇
  2014年   125篇
  2013年   143篇
  2012年   238篇
  2011年   235篇
  2010年   112篇
  2009年   98篇
  2008年   154篇
  2007年   199篇
  2006年   190篇
  2005年   187篇
  2004年   161篇
  2003年   157篇
  2002年   129篇
  2001年   12篇
  2000年   6篇
  1999年   12篇
  1998年   10篇
  1997年   7篇
  1996年   6篇
  1995年   9篇
  1994年   3篇
  1992年   7篇
  1991年   4篇
  1990年   8篇
  1989年   3篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1983年   6篇
  1979年   4篇
  1978年   5篇
  1976年   5篇
  1975年   8篇
  1974年   15篇
  1973年   8篇
  1972年   4篇
  1971年   2篇
  1970年   3篇
  1969年   5篇
  1968年   2篇
  1967年   2篇
排序方式: 共有2927条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Unsaturated ketones ( 4 and 10 ) and epoxides ( 2–3 and 8–9 ) were the main products of biotransformation performed by means of Zoophthora (Neopandora) phyllobii. Enantiospecificity of both reactions leading to these compounds strongly depends on the distance of reacting fragment of molecule from the chiral center at C-1′.  相似文献   
5.
Low levels of the intracellular mediator of glutamate receptor activation, neuronal nitric oxide synthase (nNOS) were previously observed in locus coeruleus (LC) from subjects diagnosed with major depression. This finding implicates abnormalities in glutamate signaling in depression. Receptors responding to glutamate in the LC include ionotropic N-methyl-D-aspartate receptors (NMDARs). The functional NMDAR is a hetero-oligomeric structure composed of NR1 and NR2 (A-D) subunits. Tissue containing the LC and a nonlimbic LC projection area (cerebellum) was obtained from 13 and 9 matched pairs, respectively, of depressed subjects and control subjects lacking major psychiatric diagnoses. NMDAR subunit composition in the LC was evaluated in a psychiatrically normal subject. NR1 and NR2C subunit immunoreactivities in LC homogenates showed prominent bands at 120 and 135 kDa, respectively. In contrast to NRI and NR2C, very weak immunoreactivity of NR2A and NR2B subunits was observed in the LC. Possible changes in concentrations of NR1 and NR2C that might occur in depression were assessed in the LC and cerebellum. The overall amount of NR1 immunoreactivity was normal in the LC and cerebellum in depressed subjects. Amounts of NR2C protein were significantly higher (+ 61%, p = 0.003) in the LC and modestly, but not significantly, elevated in the cerebellum (+ 35%) of depressives as compared to matched controls. Higher levels of NR2C subunit implicate altered glutamatergic input to the LC in depressive disorders.  相似文献   
6.
7.
Electrical stimulation of the phrenic nerve afferents evoked excitatory responses in the right inferior cardiac sympathetic nerve in chloralose-anaesthetized cats. The reflex was recorded in intact and spinal cats. The latency and threshold of the volley recorded from the phrenic nerve as well as of the cord dorsum potentials evoked by electrical stimulation of the phrenic nerve indicated that group III afferents were responsible for this reflex. The phrenicocardiac sympathetic reflex recorded in intact cats was followed by a silent period. The maximum amplitude of the reflex discharges was 800 microV, the latency was 83 ms and the central transmission time 53 ms. Duration of the silent period lasted up to 0.83 s. In spinal cats the reflex was recorded 5.5-8 h after spinalization. The maximum amplitude of the spinal reflex discharges ranged from 22 to 91 microV and the latency from 36 to 66 ms.  相似文献   
8.
Purified murein from Thiobacillus neapolitanus was poorly digested by lysozyme. It's sensitivity to the enzyme greatly increased after N-acetylation. The murein was found to contain 30 to 35% glucosamine residues lacking N-acetyl groups. It also contained phosphomuramic acid. Further modifications included amidation of diaminopimelic acid in the peptide side chains and a low alanine content. None of these modifications were found in the murein of another sulphur bacterium, Thiobacillus versutus.  相似文献   
9.
10.
We examined 83 mothers from Szczecin (north-west part of Poland) and their 83 neonates. Concentrations of total and ionized magnesium in maternal and cord serum, as well as total magnesium in hair were determined. Higher levels of total magnesium were noted in neonates (cord serum, hair) than mothers. A positive correlation was ascertained between total magnesium in maternal and cord serum. Magnesium in maternal hair correlated negatively with ionized magnesium in cord serum. Male neonates demonstrated higher levels of magnesium in cord blood and hair than females. There was no effect of maternal age, education level, or number of past pregnancies on the concentration of magnesium in mothers or neonates.  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