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   1646篇
  免费   107篇
  国内免费   8篇
耳鼻咽喉   6篇
儿科学   105篇
妇产科学   33篇
基础医学   169篇
口腔科学   39篇
临床医学   225篇
内科学   310篇
皮肤病学   20篇
神经病学   182篇
特种医学   321篇
外科学   128篇
综合类   22篇
预防医学   44篇
眼科学   10篇
药学   72篇
中国医学   6篇
肿瘤学   69篇
  2023年   8篇
  2022年   4篇
  2021年   19篇
  2020年   15篇
  2019年   18篇
  2018年   38篇
  2017年   23篇
  2016年   26篇
  2015年   36篇
  2014年   45篇
  2013年   44篇
  2012年   54篇
  2011年   45篇
  2010年   56篇
  2009年   76篇
  2008年   51篇
  2007年   39篇
  2006年   40篇
  2005年   35篇
  2004年   37篇
  2003年   44篇
  2002年   38篇
  2001年   45篇
  2000年   36篇
  1999年   45篇
  1998年   55篇
  1997年   61篇
  1996年   79篇
  1995年   54篇
  1994年   47篇
  1993年   60篇
  1992年   35篇
  1991年   23篇
  1990年   34篇
  1989年   54篇
  1988年   47篇
  1987年   36篇
  1986年   43篇
  1985年   36篇
  1984年   20篇
  1983年   17篇
  1982年   28篇
  1981年   23篇
  1980年   13篇
  1979年   10篇
  1978年   8篇
  1977年   16篇
  1976年   17篇
  1975年   17篇
  1973年   3篇
排序方式: 共有1761条查询结果,搜索用时 15 毫秒
991.
992.
Summary. To extend our earlier data on synergistic action of tetrahydroisoquinolines and morphine, we have investigated the analgesic effects of 1,2,3,4-tetrahydroisoquinoline (TIQ) and its 1-methyl-(1-MeTIQ) and N-methyl (N-MeTIQ) analogs on analgesia induced by morphine and oxotremorine. 1-MeTIQ and N-MeTIQ induced a moderate, delayed and prolonged analgesic action measured in the tail-flick test in CD-1 mice; 1-MeTIQ and TIQ prolonged the opiate (morphine, 2.5mg/kg ip) analgesia while TIQ and N-TIQ potentiated cholinergic (oxotremorine, 0.02mg/kg ip) analgesia. The involvement of the opioid and noradrenergic systems in this effect is discussed.Received April 14, 2003; accepted July 9, 2003 Published online September 15, 2003  相似文献   
993.
目的 :保障儿童眼睛的健康。方法 :采用综合疗法治疗儿童弱视 2 4 0例 4 4 6眼。结果 :总治愈率为 6 8.6 % ,治疗有效率为 99.3%。各类弱视治愈率分别为 :轻度 91.1%、中度 77.3%、重度 16 .4 % ;3~ 7岁年龄段治愈率为 78.0 %、8~ 10岁为 6 1.0 % ;屈光不正性弱视治愈率为 75 .4 %、屈光参差性弱视为 6 7.4 %、斜视性弱视为 39.6 %、形觉剥夺性弱视为 16 .7% ;中心性注视占80 .1%、旁中心性注视占 37.5 %。结论 :弱视的治疗效果与年龄、弱视程度、注视性质、弱视类型有密切关系 ,即弱视程度越轻 ,年龄处于 3~ 7岁者效果越好。中心性注视治疗效果好于旁中心性注视。建议 :弱视早期发现、早期综合治疗。  相似文献   
994.
The miniaturization process applied to rubredoxins generated a class of peptide-based metalloprotein models, named METP (miniaturized electron transfer protein). The crystal structure of Desulfovibrio vulgaris rubredoxin was selected as a template for the construction of a tetrahedral (S(gamma)-Cys)(4) iron-binding site. Analysis of the structure showed that a sphere of 17 A in diameter, centered on the metal, circumscribes two unconnected approximately C(2) symmetry related beta-hairpins, each containing the -Cys-(Aaa)(2)-Cys- sequence. These observations provided a starting point for the design of an undecapeptide, which self assembles in the presence of tetrahedrally coordinating metal ions. The METP peptide was synthesized in good yield by standard methodologies. Successful assembly of the METP peptide with Co(II), Zn(II), Fe(II/III), in the expected 2:1 stoichiometry, was proven by UV-visible and circular dichroism spectroscopies. UV-visible analysis of the metal complexes indicated the four Cys ligands tetrahedrally arrange around the metal ion, as designed. Circular dichroism measurements on both the free and metal-bound forms revealed that the metal coordination drives the peptide chain to fold into a turned conformation. NMR characterization of the Zn(II)-METP complex fully supported the structure of the designed model. These results prove that METP reproduces the main features of rubredoxin.  相似文献   
995.
Lipomatous tumors of the stomach: CT findings and differential diagnosis   总被引:3,自引:0,他引:3  
This article reviews the computed tomography imaging features of a variety of gastric tumors containing fatty tissue. Lipoma, angiolipoma, liposarcoma, and teratoma are described. Differential diagnosis includes primary and reactive lipomatosis, carcinoma engulfing the perivisceral fat thus mimicking differentiated liposarcoma, and mesenchymal gastric and peritoneal neoplasms.  相似文献   
996.
The term hypomelanosis of Ito is applied to individuals with skin hypopigmentation along the lines of Blaschko. Even though originally described as a purely cutaneous disease, subsequent reports have included a 33% to 94% association with multiple extracutaneous manifestations mostly of the central nervous and musculoskeletal systems leading to frequent characterization as a neurocutaneous disorder. A number of reports claimed familial occurrence and supported single gene inheritance for hypomelanosis of Ito, but none has been proved. Miscellaneous chromosomal mosaicisms have been demonstrated in some but not all affected individuals. Thus, it has been suggested that hypomelanosis of Ito is not a single condition but rather a nonspecific manifestation (ie, a phenotype) of chromosomal mosaicism and that this term should now be dropped. In this article, we review these developments focusing on the neurologic and genetic aspects of hypomelanosis of Ito. Our personal experience with 41 hypomelanosis of Ito patients and literature review led us to conclude that (1) the term hypomelanosis of Ito has been often misapplied to individuals with nonspecific "patchy depigmentation of the skin" who had several conditions of different etiologies; (2) the white matter involvement seen at neuroimaging in most of our hypomelanosis of Ito patients was similar to that reported in well-defined neurocutaneous disorders, including Sj?gren-Larsson syndrome and incontinentia pigmenti; (3) whatever figures we take for associated central nervous system abnormalities in hypomelanosis of Ito, these represent the most frequent extracutaneous findings and, therefore, the use of the term neurocutaneous disorder for hypomelanosis of Ito might well be appropriate.  相似文献   
997.
PURPOSE: MOPPEBVCAD (mechlorethamine, vincristine, procarbazine, prednisone, epidoxirubicin, bleomycin, vinblastine, lomustine, doxorubicin, and vindesine) chemotherapy with limited radiotherapy was devised in 1987 to reduce late toxicity and second tumor incidence while trying to improve effectiveness through increases of dose intensity and dose density. Late results, toxicity, and second tumor incidence were reviewed in all the patients treated. EXPERIMENTAL DESIGN: The drugs of three previous alternating regimens [CAD (lomustine, melphalan, and vindesine), MOPP (mechlorethamine, vincristine, procarbazine, and prednisone), and ABV (doxorubicin, bleomycin, and vinblastine)] were intensified and hybridized, the cumulative dose of mechlorethamine was lowered, and irradiation was delivered to no more than two sites either bulky or partially responding to chemotherapy. RESULTS: A total of 307 previously untreated advanced-stage patients underwent MOPPEBVCAD chemotherapy. Radiotherapy was delivered to 118 of 307 patients (38%). Remission was complete in 290 patients (94%). With a median follow-up of 114 months, 10-year overall, disease-free, and failure-free survival rates were 79%, 84%, and 71%, respectively. Forty-two patients relapsed and 60 died. The causes of death were Hodgkin's lymphoma in 36 patients, second neoplasms in 12, cardiorespiratory diseases in 4, pulmonary diseases in 2, and unknown in 6. Sixteen second tumors (of which nine were myelodysplasia and/or acute leukemia) were diagnosed in all. Outside this series of 307 patients, MOPPEBVCAD obtained complete responses in 12 of 15 relapsed and 9 of 9 refractory patients who had previously been treated with other regimens. CONCLUSIONS: Clinical response and long-term results are very satisfactory, whereas the second tumor incidence was lower than would have been expected with MOPP analogues. Given its response/late toxicity balance, MOPPEBVCAD does not undermine the leading role of ABVD as first-line regimen but can be indicated as a very effective second-line conventional therapy.  相似文献   
998.
Nineteen girls adopted from developing countries were referred for signs of idiopathic precocious puberty. After adoption, the catch up in linear and weight growth, together with improved nutritional and psychological conditions, may trigger the onset of puberty. Precocious puberty is a frequent and unnatural event in these girls. Treatment with gonadotrophin releasing analogues is indicated in patients diagnosed early, and when height prediction is poor.  相似文献   
999.
Mother-to-infant transmission of hepatitis C virus   总被引:1,自引:0,他引:1  
Anti-hepatitis C virus (HCV) antibodies and HCV-RNA were measured in the sera of 22 anti-HCV positive, HIV-1 negative mothers and their infants. ELISA and RIBA II were used for anti-HCV determination. HCV-RNA was measured by a nested polymerase chain reaction. HCV-RNA was found in 12 of 22 mothers. All 22 children were followed for 12 months. All were anti-HCV positive by the fourth month; 18 became anti-HCV negative between the 8th and 12th month. HCV-RNA was detected in 5 of 22 infants in the fourth month. They remained HCV-RNA positive. All children born to HCV-RNA negative mothers were HCV-RNA negative while 5 of 12 babies born to HCV-RNA positive mothers were infected. All five infected babies were born to mothers infected through transfusions or drug use. ALT levels in mothers seemed to have no effect on mother-to-infant transmission. Hence evidence for perinatal transmission of HCV from HCV-RNA positive mothers was demonstrated in the present study.  相似文献   
1000.
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