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   31877篇
  免费   3094篇
  国内免费   2252篇
耳鼻咽喉   240篇
儿科学   424篇
妇产科学   380篇
基础医学   3577篇
口腔科学   566篇
临床医学   4297篇
内科学   4739篇
皮肤病学   279篇
神经病学   1542篇
特种医学   1342篇
外国民族医学   13篇
外科学   3596篇
综合类   5363篇
现状与发展   8篇
一般理论   3篇
预防医学   2077篇
眼科学   725篇
药学   3447篇
  38篇
中国医学   1799篇
肿瘤学   2768篇
  2024年   119篇
  2023年   514篇
  2022年   1270篇
  2021年   1600篇
  2020年   1192篇
  2019年   1040篇
  2018年   1065篇
  2017年   1015篇
  2016年   1013篇
  2015年   1443篇
  2014年   1780篇
  2013年   1597篇
  2012年   2093篇
  2011年   2469篇
  2010年   1600篇
  2009年   1262篇
  2008年   1625篇
  2007年   1689篇
  2006年   1593篇
  2005年   1552篇
  2004年   1191篇
  2003年   1192篇
  2002年   1073篇
  2001年   910篇
  2000年   829篇
  1999年   798篇
  1998年   465篇
  1997年   525篇
  1996年   348篇
  1995年   312篇
  1994年   241篇
  1993年   195篇
  1992年   235篇
  1991年   214篇
  1990年   186篇
  1989年   167篇
  1988年   137篇
  1987年   137篇
  1986年   120篇
  1985年   76篇
  1984年   50篇
  1983年   28篇
  1982年   16篇
  1981年   17篇
  1980年   25篇
  1979年   45篇
  1978年   22篇
  1976年   12篇
  1975年   18篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
1-N HAPA gentamicin B is a new aminoglycoside active against most Enterobacteriaceae, Pseudomonas aeruginosa and Staphylococcus aureus. Among 504 clinical isolates at a concentration of 12.5 microgram/ml all Staph. aureus, Escherichia coli, Klebsiella, Enterobacter, Proteus rettgeri, Providencia and 78% of Pseudomonas, 86% of Proteus morganii were inhibited. Like other aminoglycosides, the activity was greatest at an alkaline ph and reduced by high cations concentrations. 1-N HAPA gentamicin B was equal in activity to amikacin against both gentamicin-sensitive and resistant isolates. It inhibited bacteria containing many of the aminoglycoside inactivating enzymes. When combined with carbenicillin it inhibited in a synergistic manner many Gram-negative bacteria, particularly Pseudomonas and Serratia.  相似文献   
92.
Fu PP  Beland FA  Yang SK 《Carcinogenesis》1980,1(8):725-727
Cyclopenta-polycyclic aromatic hydrocarbons (cyclopenta-PAHs) are a group of compounds that have been detected as environmental pollutants. Perturbation molecular orbital (PMO) calculations on their presumed ultimate carcinogenic metabolites, the cyclopenta-PAH expoxides, predict that they may have a greater biological hazard than the classic PAHs.  相似文献   
93.
H Fu 《中华医学杂志》1992,72(5):280-3, 319
Fourteen points superficial bloodflow (SBF) of the skin and tongue in 55 patients with acute myocardial infarction (AMI) were measured at 12, 24, 36, 48, 60 hours and 3, 5, 7, 10, 14, 21, 28 days after AMI by LDF (PF2). The dynamic study on multiple points SBF of 576 times showed that (1) The mean SBF of skin was 1.0 +/- 0.04 (V) at 12 hours after AMI. It occupied 70.5% in the normal control. After therapy at 48 hours of AMI, the mean SBF was increased to 1.20 +/- 0.03 (V), and approximated 85.9% of the control. (2) The mean SBF in patients with cardiogenic shock was 1.04 +/- 0.05 (V), and it was significantly lower than that without complications (P less than 0.01). The mean SBF showed a negative correlation with the nailfold microcirculatory values (P less than 0.0025). There was a negative correlation between "Tanzhong" SBF and cardiac muscle enzyme CPK, GOT, LDH (P less than 0.05). (3) The SBF of acupuncture point "Tanzhong, Erxin" related to the heart might more sensitively represent the cardiac condition in AMI. (4) The SBF of tongue was negatively correlated with GOT (P less than 0.05). (5) Continual peripheral microcirculatory observation and electrocardiographic monitoring would be helpful in the diagnosis and treatment of earlier complications of AMI in order to reduce the mortality.  相似文献   
94.
Y S Fu  K H Perzin 《Cancer》1979,43(2):611-621
In our series of 256 nonepithelial tumors involving the nasal cavity, paranasal sinuses and nasopharynx, 21 were apparently primary malignant lymphomas, including 17 ordinary lymphomas and 4 cases of "midline malignant reticulosis." Of the 15 patients who had ordinary lymphomas and had adequate follow-up, 8 died of lymphoma, 4 were living with disseminated disease, 1 died of other causes with persistent lymphoma and only 2 (13%) had no evidence of recurrence at 8 and 9 years after diagnosis. The tumor was controlled in its primary site by radiotherapy in 13 of 14 patients; however, all but 2 of these patients eventually developed disseminated disease. Of the 3 patients who had midline malignant reticulosis (MMR) and had adequate follow-up, all died of disease. MMR represents an unusual variant of malignant lymphoma and often produces the clinical picture of lethal midline granuloma.  相似文献   
95.
目的 研究可溶性血管细胞黏附分子 1(solublevascularcelladhesionmolecule - 1,sVCAM - 1)在妊高征发病中的作用。方法 用酶联免疫吸附法 (ELISA)测定 6 7例孕妇血清中sVCAM - 1水平 ,其中正常妊娠组 15例 ,妊高征组 5 2例。结果 中、重度妊高征患者血中sV CAM - 1水平显著高于正常妊娠组 (P <0 .0 1) ;轻度妊高征患者与正常妊娠组相比 ,虽无统计学差异 ,但有升高趋势 ;妊高征组产后该指标下降 ,与正常妊娠组比较无显著性差异 (P >0 0 5 )。sVCAM - 1浓度与平均动脉压呈正相关 (r =0 .5 4 2 ,P <0 .0 1)。结论 妊高征患者血中sVCAM - 1水平升高 ,表明内皮细胞损伤在妊高征的发病中起重要作用。  相似文献   
96.
Objective Discussion of diagnosis, treatment and prognosis of non-palpable TO breast cancer. Methods Between 1978 and 1997, 9,980 female patients with operable breast cancer were treated surgically, of which 276 were determined to have TO breast cancer. Most TO breast cancers could be detected promptly with careful examination of presenting symptoms, such as nipple discharge, local thickening of the breast, nipple erosion, nipple retraction and postmenopausal mastalgia, while 12 cases were detected by routine mammography of the contralateral breast. Results All patients were treated surgically and their tissue subjected to histopathological examination. Most cases (73.0%) were noninvasive or early invasive carcinoma. Axillary lymph nodes metastases were found in 7.69% of 234 mastectomy cases. Conclusion The survival rate was significantly increased if the tumor was in an early stage. The 5-, 10-, 15-years survival rates were 98.1%, 94.6% and 90.3%, respectively.  相似文献   
97.
98.
TGF beta-1 has been shown to upregulate matrix synthesis in articular chondrocytes. TGF beta-gene transfer to chondrocytes has the potential to increase the local production of this key component within regenerating cartilage after trauma and could support the repair process in articular cartilage lesions. Primary rabbit articular chondrocytes were cultured and retrovirally transfected with the experimental TGF beta-1 and the lacZ marker gene for control purposes. After radioactive labeling of new synthesized matrix proteins results were compared with normal primary chondrocytes. After TGF beta-1 gene transfer the endogenous growth factor concentration was doubled compared to normal chondrocytes and decreased in the lacZ control group. The proteoglycan synthesis in TGF beta-1 transfected chondrocytes showed a 96% increase compared to the basal production of normal chondrocytes. The LacZ transfected group revealed the opposite effect by a 44% decrease. The collagen synthesis of TGF beta-1 transfected chondrocytes was 304% compared to normal chondrocytes, predominantly type II collagen. The lacZ group collagen production was reduced by 35%. We conclude that TGF beta-1 gene transfer overcomes the decreasing effect observed by transfection with the LacZ marker gene and increases matrix synthesis in articular chondrocytes. Genetically altered chondrocytes might improve the repair of cartilage lesions by stimulating matrix synthesis and supporting the expression of the hyaline phenotype.  相似文献   
99.
AIM: Muscle-based somatic gene therapy is a novel way to alleviate a biochemical deficiency. METHOD: Muscle-derived cells are very promising in the field of gene therapy and tissue engineering. First, most muscle tissue is accessible by injection. Second, muscle tissue consists of multinucleated, postmitotic myofibers, which enable a long-term expression of the transduced gene. Third, muscle tissue can be biopsied easily. It is available in abundance and the biopsy does not compromise the health and function of the patient. Finally, muscle tissue is highly vascularized, which makes systemic delivery feasible. RESULTS: Muscle-derived cells can promote muscle healing and bone healing. Implanted cells maintain a long-term transgene expression of therapeutic proteins. Isolated, muscle-derived stem cells can differentiate in osteoblasts. CONCLUSION: Based on these characteristics, we present four possible applications: inherited muscular diseases, muscle injury, bone healing, and intraarticular disorders.  相似文献   
100.
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