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   7650篇
  免费   675篇
  国内免费   44篇
耳鼻咽喉   110篇
儿科学   233篇
妇产科学   254篇
基础医学   1036篇
口腔科学   107篇
临床医学   953篇
内科学   1767篇
皮肤病学   162篇
神经病学   836篇
特种医学   599篇
外科学   995篇
综合类   79篇
一般理论   1篇
预防医学   328篇
眼科学   134篇
药学   327篇
中国医学   13篇
肿瘤学   435篇
  2023年   66篇
  2022年   59篇
  2021年   112篇
  2020年   143篇
  2019年   92篇
  2018年   172篇
  2017年   133篇
  2016年   158篇
  2015年   192篇
  2014年   267篇
  2013年   336篇
  2012年   349篇
  2011年   341篇
  2010年   294篇
  2009年   273篇
  2008年   322篇
  2007年   340篇
  2006年   352篇
  2005年   303篇
  2004年   264篇
  2003年   246篇
  2002年   225篇
  2001年   258篇
  2000年   228篇
  1999年   191篇
  1998年   152篇
  1997年   139篇
  1996年   138篇
  1995年   122篇
  1994年   86篇
  1993年   101篇
  1992年   137篇
  1991年   133篇
  1990年   131篇
  1989年   149篇
  1988年   133篇
  1987年   104篇
  1986年   82篇
  1985年   91篇
  1984年   70篇
  1983年   48篇
  1982年   45篇
  1979年   68篇
  1978年   39篇
  1977年   48篇
  1975年   39篇
  1974年   44篇
  1973年   45篇
  1972年   46篇
  1971年   44篇
排序方式: 共有8369条查询结果,搜索用时 15 毫秒
41.
In previous publications we showed that neopterin, a pyrazino-pyrimidin compound, represents a biochemical marker for the assessment of cellular immune responses. We thought that the evaluation of this marker molecule might enable insight into the activity of cellular immune responses underlying ulcerative colitis (UC). Evaluation of urinary neopterin excretion in 25 consecutive untreated UC patients revealed striking correlations between neopterin levels and the severity of disease: elevated levels were observed in 9 out of 9 patients with moderately severe to severe, in 3 of 4 with mild and in none of 12 patients with quiescent disease. Further evidence for a correlation between disease activity and neopterin excretion was obtained on the basis of long-term follow-up studies performed in 4 cases. These studies indicated normalization of neopterin levels when clinical remission was achieved. Thereafter, the relative significance of neopterin excretion for determination of clinical stage was assessed by linear correlation analyses and was compared with conventional clinical parameters such as anemia, number of motions per day, raised temperature, ESR and extent of bowel involvement. The logarithm of neopterin excretion and the extent of bowel involvement were the two single parameters most closely related to the clinical stage of ulcerative colitis. We, therefore, conclude that evaluation of neopterin excretion in ulcerative colitis patients represents a new and useful tool for the clinical monitoring of disease activity.  相似文献   
42.
43.
Functional properties of a crossed spinocerebellar tract with cell bodies located in laminae VII and IX of the S1 segment were investigated using intracellular recording. The neurones were found to be excited by group I and II muscle afferents and afferents of skin, joint and interosseus nerves. Volleys from group II muscle afferents and cutaneous afferents evoked inhibition in these cells. It is concluded that S1 spinocerebellar neurones convey a similar type of information to that of dorsal spinocerebellar tract and ventral spinocerebellar tract neurones but integrate it in a different way.  相似文献   
44.
Cicatricial conjunctivitis may be a sequel to systemic disorders (eg, Stevens-Johnson syndrome, cicatricial pemphigoid) or local disorders such as chemical burns. The cicatrisation is often associated with corneal epithelial changes that cause visual loss. These have been attributed to encroachment of the conjunctival epithelium over the cornea. However, the epithelial anomalies are poorly understood. We investigated the corneal epithelial changes in cicatricial conjunctivitis with an immunohistochemical study of intermediate filaments in normal and pathological specimens. Our results show that the normal corneal epithelium is immunoreactive for cytokeratin 3 (CK 3) but not cytokeratin 19 (CK 19), whereas normal conjunctival epithelium is CK 3 negative and CK 19 positive. Conjunctiva artificially transposed over the cornea (after therapeutic conjunctival flap reconstruction) retained the normal pattern of conjunctival cytokeratin expression (CK 3 negative, CK 19 positive). Conversely, the entire corneal epithelium exhibited the normal cytokeratin pattern (CK 3 positive, CK 19 negative) in 82% of Stevens-Johnson, 80% of cicatricial pemphigoid, and 69% of chemical burns specimens. The findings suggest that conjunctival encroachment is not responsible for the changes at the corneal surface in cicatricial conjunctivitis and that the abnormal corneal epithelium is derived from native corneal cells in these diseases.  相似文献   
45.
The effect of integrating a Drug Usage Guidelines (DUG) program with a hospital formulary system was analyzed. Significant changes were observed in both the number of requests submitted to the P & T Committee and the number of drugs added to the formulary after implementation of the DUG program. Failure to follow the DUG submission protocol, particularly with respect to the requirement for supportive clinical data from the primary literature, led to delayed consideration and eventual withdrawal of several highly promoted drug products. The initial involvement of physicians in the planning and implementation of the DUG program has been an important factor in the continued success of the program.  相似文献   
46.
Memory impairment associated with progression of Huntington's disease   总被引:2,自引:0,他引:2  
Huntington's Disease (HD) has been described as one example of a "subcortical" dementia, characterized by slowed cognitive processing and impairment of memory. We examined the relationship between slowed cognitive processing and memory impairment as a function of disease progression in patients with HD. Results from three experiments suggest that in the early stages of HD there is slowed cognition with intact memory acquisition and retrieval processes. In later stages, cognition is further slowed and specific impairments of memory become evident. Thus, memory impairment in HD would appear to change qualitatively with progression of the disease.  相似文献   
47.

The Fast Friends Procedure (FFP) is a widely used experimental paradigm to induce emotional intimacy. Besides exploring the validity of a German translation of the paradigm (n?=?46), we developed an extension of the FFP that induces sexual intimacy and assessed heart rate, high-frequency heart rate variability, and electrodermal activity responses to the FFP and its extension. Furthermore, we examined its applicability to individuals with childhood maltreatment (n?=?56), who frequently suffer from intimacy-related difficulties. Intimacy, positive affect, liking, and attraction increased during the FFP and partly during the sexual intimacy extension in both study groups. Moreover, both groups showed physiological responses consistent with positive social interactions. The use of the German FFP and its sexual intimacy extension can thus be recommended for research in the general population and in individuals with childhood maltreatment, although more studies are needed to further validate the paradigms.

  相似文献   
48.
The peroxisome proliferator (PP) nafenopin (NAF) enhanced tumordevelopment in rat liver through promotion of a subtype of putativepreneoplastic cell foci, characterized by weak cytoplasmic basophilia(1,2). In order to elucidate the selective growth advantageof these weakly basophilic foci (WBF) we investigated the effectsof NAF on their metabolic phenotype and DNA synthesis. In WBF,as well as in other foci subpopulations and in hepatocellularcarcinomas the occurrence of five NAF-inducible enzymes, i.e.of peroxisomal ß-oxidation (acyl-CoA oxidase, bifunctionalprotein and thiolase), catalase and cytochrome P-452 was studiedby immunohistochemical methods. In untreated livers almost allfoci were stained with the same intensity as the surroundingtissue. When NAF was applied, most of the liver foci showedconsiderably less staining than the non-focal parenchyma inwhich pronounced enzyme induction had occurred. However, thesubpopulation of WBF showed a more heterogeneous pattern ofenzyme expression varying from less to even more than in theadjacent tissue. A similarly broad range of expression of peroxisomalenzymes was found in hepatocellular carcinomas. On average,however, the tumors exhibited less staining and lower activityof peroxisomal ß-oxidation than the surrounding parenchyma.WBF always showed higher rates of DNA synthesis than other focisubtypes and unaltered liver. In  相似文献   
49.
50.
This article provides an overview of current trends in health expenditures in 29 OECD countries and recent revisions of OECD health accounts. U.S. health expenditures are compared with those of other OECD countries. The interactions of cost-containment measures with changes in the public-private mix of financing and in the composition of health care spending are discussed.  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