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   2375199篇
  免费   195088篇
  国内免费   4209篇
耳鼻咽喉   34265篇
儿科学   72791篇
妇产科学   62938篇
基础医学   334941篇
口腔科学   67531篇
临床医学   215584篇
内科学   468675篇
皮肤病学   47962篇
神经病学   200829篇
特种医学   95963篇
外国民族医学   886篇
外科学   360434篇
综合类   56232篇
现状与发展   1篇
一般理论   978篇
预防医学   190679篇
眼科学   55465篇
药学   177558篇
  4篇
中国医学   4366篇
肿瘤学   126414篇
  2018年   24217篇
  2016年   20582篇
  2015年   23289篇
  2014年   33544篇
  2013年   50856篇
  2012年   68766篇
  2011年   72298篇
  2010年   42488篇
  2009年   40873篇
  2008年   68776篇
  2007年   73119篇
  2006年   74010篇
  2005年   72058篇
  2004年   69350篇
  2003年   67034篇
  2002年   66279篇
  2001年   112470篇
  2000年   116544篇
  1999年   98349篇
  1998年   27869篇
  1997年   25529篇
  1996年   25454篇
  1995年   24614篇
  1994年   23167篇
  1993年   21553篇
  1992年   79389篇
  1991年   76404篇
  1990年   73582篇
  1989年   70853篇
  1988年   65858篇
  1987年   64809篇
  1986年   61339篇
  1985年   58403篇
  1984年   44232篇
  1983年   37659篇
  1982年   22888篇
  1981年   20336篇
  1980年   19037篇
  1979年   41304篇
  1978年   28994篇
  1977年   24346篇
  1976年   22836篇
  1975年   23971篇
  1974年   29640篇
  1973年   28053篇
  1972年   26234篇
  1971年   24157篇
  1970年   22761篇
  1969年   21094篇
  1968年   19141篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
931.
Diastematomyelia is a congenital dysraphism of the spinal cord in which the affected segment is longitudinally divided by a band of fibrous tissue, cartilage, or bone. Diastematomyelia has been well described in the cervical, thoracic, lumbar, and sacral spinal cord; this paper presents a case involving the basicranium. Based on the early embryologic development of the basicranium and brain, this case demonstrates that the same mechanisms proposed as the origin of spinal diastematomyelia may also operate at a more cephalad level.  相似文献   
932.
We examined binding to excitatory amino acid and inhibitory amino acid receptors in frozen hippocampal sections prepared from surgical specimens resected from 8 individuals with medically refractory temporal lobe epilepsy. The excitatory receptors studied included N-methyl-D-aspartate (NMDA), strychnine-insensitive glycine, phencyclidine, and quisqualate. The inhibitory receptors studied were gamma-aminobutyric acid type A (GABAA) and benzodiazepine. Excitatory and inhibitory amino acid receptor binding were differentially altered in the patients with temporal lobe epilepsy in comparison to 8 age-comparable autopsy control subjects, and changes in receptor binding were regionally selective in four areas. Binding to phencyclidine receptors associated with the NMDA channel was reduced by 35 to 70% in all regions in the hippocampi of the patients. In contrast, binding to the NMDA recognition site and its associated glycine modulatory site was elevated by 20 to 110% in the cornu ammonis (CA) 1 area and dentate gyrus of the hippocampus of the patients. Binding to these sites was unaffected in area CA4. Binding to the quisqualate-type excitatory amino acid receptor was unchanged in all regions except the stratum lacunosum moleculare CA1, where it was increased by 63%. GABAA and benzodiazepine receptor binding was reduced by 20 to 60% in CA1 and CA4, but unchanged in dentate gyrus. The data indicate that excitatory and inhibitory amino acid receptors are altered in the hippocampus of patients with temporal lobe epilepsy.  相似文献   
933.
Beta-adrenergic receptor density on T cells from healthy humans is greatest on suppressor cells (CD8+, CD28-) and the effect of catecholamines, secreted by the sympathetic nervous system, predominates on this subset. The sympathetic skin response, a measure of sympathetic nervous system function, is absent in most patients with chronic progressive multiple sclerosis (MS). We measured beta-adrenergic receptor density on suppressor cells, cytotoxic cells, and monocytes from patients with chronic progressive MS and healthy control subjects. Control receptor density on suppressor cells was 2.8 +/- 0.3 fmol/10(6) cells versus a density of 5.1 +/- 0.7 fmol/10(6) cells for patients. Cytotoxic cell (CD8+, CD28+) receptor density was 1.4 +/- 0.4 fmol/10(6) cells in control subjects and 0.9 +/- 0.3 fmol/10(6) cells in the patients. Monocytes displayed beta-adrenergic receptor densities of 2.6 +/- 0.4 fmol/10(6) cells in normal individuals and 2.7 +/- 0.4 fmol/10(6) cells in the patient group. CD8 lymphocyte beta-adrenergic receptor densities in patients with relapsing-remitting and those with stable MS were not different from control values, yet were significantly less than the values for patients with chronic progressive MS. We find that mononuclear cells from healthy control subjects and patients with chronic progressive MS proliferate in response to 200 units/ml of recombinant human interleukin-2 (IL-2) similarly. However, IL-2 treatment increased beta-adrenergic receptor density on normal mononuclear cells, but failed to increase it on mononuclear cells from patients with chronic progressive MS.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
934.
Artificial dopamine agonists are widely employed for the treatment of idiopathic parkinsonism. Pleuropulmonary disease has previously been reported to occur with the use of bromocriptine and mesulergine. We report similar adverse effects induced by the newer agonists lisuride and cabergoline. All these agents are tetracyclic ergot derivatives. This suggests a causal link between ergot-derived dopamine agonists and pleuropulmonary disease.  相似文献   
935.
Reports on individual nonbehavioral child and adolescent psychotherapy since 1963 are reviewed. Inclusion criteria required some minimal contrasting group. Forty-three studies were assessed for basic methodological adequacy and main findings. The authors conclude that summary impressions from this body of literature cannot be made due to the magnitude of the flaws in basic psychotherapy research methodology. Suggestions are made regarding the future of child and adolescent psychotherapy research.  相似文献   
936.
937.
938.
Computer tomography (CT) of the brain is of value for finding potentially correctable lesions in adult patients with new onset seizures. The value of CT is unknown, however, for finding such lesions in adult chronic epileptic patients without prior CT. We compared a group of 177 adult patients who had CT within a year from the onset of seizures to a group of 93 patients who had a history of seizures for more than a year before CT was performed. In the first group, 33 potentially correctable lesions (19%) were found including 17 tumors. The group with chronic epilepsy had 4 (4%) potentially correctable lesions: 3 arteriovenous malformations and 1 meningioma. It seems that CT is of value in discovering potentially removable lesions in chronic epileptic patients, but the likelihood is relatively small. The incidence of stable structural lesions seems to be similar in the two groups.  相似文献   
939.
Forty-two therapists conducting individual psychotherapy with schizophrenic outpatients in a public mental health system responded to a questionnaire that focused on the types of interventions used and the issues and problems encountered in therapy. The therapists spent 59 percent of their time in supportive, problem-solving work and only 32 percent in traditional psychotherapeutic interventions, such as providing insight. The most common issues in therapy were relationship problems, family concerns, depression, losses, and the role of medications in the client's life. The most significant impediments to therapeutic work were the lack of community resources, the client's noncompliance with medications and lack of motivation, and dual diagnoses. Suggestions are offered for improving psychotherapy with schizophrenic outpatients in the public mental health system.  相似文献   
940.
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