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   17028篇
  免费   1510篇
  国内免费   53篇
耳鼻咽喉   338篇
儿科学   516篇
妇产科学   593篇
基础医学   2153篇
口腔科学   324篇
临床医学   2381篇
内科学   2987篇
皮肤病学   165篇
神经病学   1775篇
特种医学   881篇
外科学   2573篇
综合类   267篇
一般理论   10篇
预防医学   1385篇
眼科学   477篇
药学   940篇
中国医学   11篇
肿瘤学   815篇
  2023年   109篇
  2022年   127篇
  2021年   352篇
  2020年   226篇
  2019年   323篇
  2018年   440篇
  2017年   390篇
  2016年   356篇
  2015年   414篇
  2014年   572篇
  2013年   764篇
  2012年   1049篇
  2011年   1035篇
  2010年   696篇
  2009年   566篇
  2008年   860篇
  2007年   924篇
  2006年   952篇
  2005年   887篇
  2004年   733篇
  2003年   801篇
  2002年   724篇
  2001年   323篇
  2000年   268篇
  1999年   318篇
  1998年   282篇
  1997年   237篇
  1996年   253篇
  1995年   192篇
  1994年   165篇
  1993年   142篇
  1992年   211篇
  1991年   219篇
  1990年   198篇
  1989年   189篇
  1988年   176篇
  1987年   188篇
  1986年   162篇
  1985年   175篇
  1984年   134篇
  1983年   120篇
  1982年   102篇
  1981年   96篇
  1980年   93篇
  1979年   94篇
  1978年   106篇
  1977年   88篇
  1976年   88篇
  1975年   75篇
  1974年   80篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
OBJECTIVE: This study retrospectively explored the late-life functional status of Okinawan centenarians. METHODS: Activities of daily living were measured retrospectively at five time points (10, 5, 3, and 1 year prior and present) for 22 centenarians in relation to seven physical, two sensory, and two cognitive functions using the Inoue Index. RESULTS: In all, 82% of individuals were still functioning independently at a mean age of 92 years and almost two-thirds were still functioning independently at a mean age of 97 years. CONCLUSION: Preliminary analyses suggest high functional status in Okinawan centenarians throughout their 90 s. The genetic and environmental factors contributing to this successful aging phenomenon deserve further investigation.  相似文献   
32.
BACKGROUND: Based on good results in the treatment of superficial skin tumours, since the early 1990s topical photodynamic therapy with aminolaevulinic acid (ALA PDT) has been used for disseminated, inflammatory dermatoses including psoriasis. However, there is still a lack of well-documented trials. OBJECTIVE: A prospective randomized, double-blind phase I/II intrapatient comparison study was conducted in 12 patients to investigate whether topical ALA PDT is an effective treatment for chronic plaque-type psoriasis. METHODS: In each patient three psoriatic plaques were randomly treated with a light dose of 20 J/cm(2) and 0.1%, 1% and 5% ALA, respectively. Treatment was conducted twice a week until complete clearance or for a maximum of 12 irradiations. Therapeutic efficacy was assessed by weekly determination of the psoriasis severity index (PSI). RESULTS: The mean percentage improvement was 37.5%, 45.6% and 51.2% in the 0.1%, 1% and 5% ALA-treated groups, respectively. Irradiation had to be interrupted several times because of severe burning and pain sensation. CONCLUSION: Topical ALA PDT did not prove to be an appropriate treatment option for plaque-type psoriasis due to disappointing clinical efficacy, the time-consuming treatment procedure and its unfavourable adverse event profile.  相似文献   
33.
34.
P-glycoprotein (Pgp) is a plasma membrane protein that was first characterised in multidrug resistant cell lines. The occurrence of Pgp in clinical tumors has been widely studied. Recent investigations have begun to focus on the relationship between Pgp detection in tumors and treatment outcome. In several types of tumors, detection of Pgp correlates with poor response to chemotherapy and shorter survival. P-glycoprotein overexpression often occurs upon relapse from chemotherapy but may also occur at the time of diagnosis. Studies of experimental rat liver carcinogenesis have shown that Pgp expression increases in late stages of carcinogenesis, suggesting that Pgp may be involved in tumor progression. While some of the Pgp isoforms are known to transport hydrophobic chemotherapeutic drugs out of tumor cells, the biologic effects of Pgp overexpression in tumor cells are not fully understood, because the spectrum of substrates for Pgp-mediated transport has not been determined. In the rat liver carcinoma model, strong expression of Pgp is associated with a highly vascular stroma, suggesting that Pgp in tumor cells may affect the connective tissue stroma. The regulation of Pgp appears to be complex, and little is known about how it is up-regulated during carcinogenesis. Further studies of the role of Pgp in malignancy may contribute to our understanding of molecular mechanisms which underlie tumor progression.  相似文献   
35.
Exposure of animals to aversive events produces stress-induced analgesia. A common method of producing stress in animals is the cold-water swim (CWS). The present series of experiments examines the effect of CWS on tonic pain, as measured by the formalin test, and explores possible mechanisms of action. Experiment 1 demonstrates that a 3.5-min swim in 2°C water produces a delayed nociceptive response (DNR), characterized by a prolonged period of no formalin responding which then begins and continues during the time when control animals, which have not received the CWS, are finished responding. The delayed response begins at 50–60 min postformalin injection, peaks at 80 min, and is still present at 120 min. Experiment 2 indicates that paw temperature effects are not responsible for the DNR, although core body temperature effects are a possible mechanism. However, systematic delays in the formalin injection following the CWS (Experiment 3) drastically altered the DNR even though core body temperature remained unchanged, suggesting that a decrease of core body temperature is insufficient to account for the DNR. Experiment 4 demonstrates that the NMDA antagonist MK-801 administered prior to the CWS dramatically reduces the DNR. The present experiment is the first study that reports a delay as long as 60 min in pain responding. It is concluded that the delayed response to formalin injection is the result of complex interactions involving peripheral mechanisms and central neuronal plasticity in which activity initiated by a noxious input persists after the cessation of the input as a consequence of a stressful event such as the cold-water swim.  相似文献   
36.
We present a patient with tuberous sclerosis and bilateral angiomyolipomaswith a right partial staghorn calculi in which the calculi was managed with a percutaneous nephrolithotomy. Despite the inherent risk of hemorrhage with a percutaneous approach compounded by the fact that this was done directly through a tumor, we were able to render the patient stone free with no intraoperative bleeding, complications, or the need for postoperative blood transfusion. To our knowledge, this is the first reported case of percutaneous nephrolithotomy directly through a renal angiomyolipoma.  相似文献   
37.
38.
This study reports on the efficacy of a 'coma arousal procedure'. This procedure involved a programme of vigorous sensory stimulation administered to comatose patients by relatives using Comakits. An experimental group of 12 severely head-injured patients received the coma arousal procedure while a matched control group did not. Total duration of coma and weekly Glasgow Coma Scale Scores were recorded for the two groups. Results indicate that the total duration of coma was significantly shorter and that coma lightened more rapidly for the experimental group.  相似文献   
39.
Treatment of confluent monolayers of human umbilical vein endothelial cells with sublethal concentrations of hydrogen peroxide (H2O2) produces reversible cell retraction that opens gaps between adjacent cells. Despite the retraction, adjacent cells remain in contact through a network of dendrite-like processes. Retraction depends on cellular metabolism but not new protein synthesis or protein kinase C. Shape changes induced by H2O2 are accompanied by partial redistribution of actin filaments from the cell periphery in resting endothelial cells to a tangled network of centrally located filaments in H2O2-treated endothelial cells. This change in actin organization is associated with a loss of the normal distribution pattern of surface protein expression. Specifically, beta 1 and beta 3 integrins partly escape from focal adhesion plaques and migrate to the lateral and apical surface of the cell; PECAM-1 redistributes from the lateral borders to the basal surface; and ICAM-1 and ICAM-2 spread from apical caps to the basal surface and to the dendrite-like processes. The likely consequence of endothelial retraction accompanied by abnormal membrane protein distribution is a loss of normal endothelial cell functions. These changes are best considered manifestations of H2O2-induced sublethal injury that may cause endothelial dysfunction.  相似文献   
40.
The surgical management of lobular carcinoma in situ (LCIS) and ductal carcinoma in situ (DCIS) remains controversial. For in situ breast cancer local excision (LE), local excision and radiation therapy (LERT) and mastectomy (MAST) have all been advocated. A search of the English literature found 13 reports concerning the surgical management of LCIS and 12 reports concerning the management of DCIS. The data were combined in a meta-analysis of outcome. As expected, recurrence rates following LE with both LCIS 8.4%) and DCIS (17%) are high. However,the overall mortality following mastectomy for recurrence, LCIS (2.8%) and DCIS (2.3%) does not differ statistically from those treated initially with mastectomy for LCIS (0.9%) and DCIS (1.7%). We conclude from these data that local recurrence after breast conserving procedures for in situ breast cancer does not carry an ominous prognosis. This knowledge should aid in planning individual therapy.  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