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   20627篇
  免费   1250篇
  国内免费   259篇
耳鼻咽喉   481篇
儿科学   197篇
妇产科学   278篇
基础医学   3275篇
口腔科学   343篇
临床医学   1477篇
内科学   4315篇
皮肤病学   672篇
神经病学   1498篇
特种医学   1362篇
外科学   3018篇
综合类   69篇
一般理论   3篇
预防医学   648篇
眼科学   424篇
药学   1731篇
中国医学   268篇
肿瘤学   2077篇
  2024年   18篇
  2023年   167篇
  2022年   508篇
  2021年   841篇
  2020年   334篇
  2019年   584篇
  2018年   689篇
  2017年   513篇
  2016年   840篇
  2015年   1108篇
  2014年   1303篇
  2013年   1363篇
  2012年   2019篇
  2011年   1839篇
  2010年   1169篇
  2009年   974篇
  2008年   1310篇
  2007年   1213篇
  2006年   951篇
  2005年   899篇
  2004年   715篇
  2003年   611篇
  2002年   534篇
  2001年   301篇
  2000年   253篇
  1999年   185篇
  1998年   103篇
  1997年   86篇
  1996年   66篇
  1995年   66篇
  1994年   48篇
  1993年   45篇
  1992年   79篇
  1991年   66篇
  1990年   46篇
  1989年   39篇
  1988年   42篇
  1987年   42篇
  1986年   29篇
  1985年   25篇
  1984年   15篇
  1983年   10篇
  1981年   9篇
  1980年   10篇
  1979年   10篇
  1978年   6篇
  1976年   7篇
  1973年   7篇
  1971年   6篇
  1968年   6篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Effects of plantago-mucilage A (P-MA) on the immune responses were studied in ICR mice. Mice were divided into 4 groups (10 mice/group), and P-MA at doses of 7, 21 and 63 mg/kg were orally administered to mice once a day for 21 consecutive days. Mice were immunized and challenged with sheep red blood cells (SRBC). P-MA at 63 mg/kg/day significantly increased the body weight gain and the relative weights of spleen and thymus, as compared with those in controls. However, there were no significant effects on liver weight due to P-MA treatment. Plaque forming cells (PFC) and hemagglutination (HA) titers to SRBC were significantly enhanced in mice dosed at 21 and 63 mg/kg/day P-MA, as compared with those in controls. Delayed-type hypersensitivity (DTH) reaction to SRBC, phagocyte activity and circulating leukocyte were also significantly increased in mice dosed at 63 mg/kg/day P-MA. These results demonstrate that P-MA markedly enhances both humoral immune and allergic reaction to SRBC at concentrations which don’t act on the relative weight of liver.  相似文献   
32.
We report a case of rare multiple internal resorptions. Etiology of multiple internal resorptions is unknown. Interestingly, the patient had an atopic dermatitis, which is possibly related to multiple and rapid internal resorptions.  相似文献   
33.
Extensive studies have shown that the current assays used to identify cattle infected with Mycobacterium bovis or Mycobacterium avium subsp. paratuberculosis are not sufficiently sensitive and specific to detect all infected animals, especially animals recently infected with the pathogens. In the present report we show that these limitations might be overcome with a latex bead agglutination assay (LBAA). With the specific immunodominant epitope (ESAT6-p) of M. bovis, we developed an LBAA and enzyme immunoassay (EIA) for that purpose and compared them with the “gold standard” culture method and skin test for their efficacy in detecting bovine tuberculosis. When sera from control healthy cows (n = 10), M. avium subsp. paratuberculosis-positive cattle (naturally infected, n = 16; experimentally infected, n = 8), and M. bovis-positive cattle (naturally infected, n = 49;experimentally infected, n = 20) were applied to an EIA and an LBAA developed with ESAT6-p, the two tests showed similar sensitivity (97.1% by EIA, 95.7% by LBAA), high specificity (94.2% by EIA, 100% by LBAA), and a positive correlation (kappa value, 0.85; correlation rate, 93.2%; correlation coefficient, 0.64). Receiver operating characteristic analysis of EIA results and comparison with the culture method determined a suitable cutoff value at 0.469, with an area under the curve of 0.991 (95% confidence interval, 0.977 to 1.0). As LBAA didn't show any positive reactions with sera from uninfected control cows or M. avium subsp. paratuberculosis-infected cattle, which were confirmed to be free of M. bovis by culture or PCR, LBAA using the ESAT6-p can be a rapid and useful M. bovis diagnostic assay. The data suggest that rapid, sensitive, and specific assays can be developed with peptides containing immunodominant epitopes present in proteins uniquely expressed in M. bovis or M. avium subsp. paratuberculosis for differential diagnosis of cattle infected with M. bovis or M. avium subsp. paratuberculosis.  相似文献   
34.
OBJECTIVES: To analyze the clinical characteristics and treatment results between bilateral (bi-) and unilateral (uni-) sudden sensorineural hearing loss (SSNHL). STUDY DESIGN AND SETTING: A retrospective study. METHODS: Three hundred twenty-four patients with SSNHL were classified into two groups; simultaneous bi-SSNHL (n = 16) and uni-SSNHL (n = 308). We compared clinical characteristics, medical history, hearing level, and treatment results between the 2 groups. RESULTS: The incidence of bi-SSNHL was 4.9 percent of overall patients with SSNHL. Bi-SSNHL occurs more commonly in patients of older age, with preexisting diabetes mellitus, and lipid panel abnormalities compared with uni-SSNHL. Ten patients (62.5%) in the bi-SSNHL group showed hearing recovery in 1 or both ears compared with 56.5 percent of patients with uni-SSNHL. Only 12 (37.5%) of all 32 ears recovered in bi-SSNHL, which was significantly lower than in uni-SSNHL. CONCLUSION: Bi-SSNHL has a very low incidence and lower recovery rate than uni-SSNHL. Recognition of similarities and differences between bilateral and unilateral SSNHL can help in counseling and managing the patients.  相似文献   
35.
The UV-pattern of several flavones, their cytotoxicities against L1210 cell and their Inhibiting effects on ATPase from the cell seem to be correlated. 5,2′-Dihydroxy-6,7,8,6′-tetramethoxyflavone (ED50=2.3 ug/ml) and 5,2′,6′-trihydroxy-6,7,8-trimethoxyflavone (ED50=4.5 ug/ml), the most active flavones studied, have shown a narrow range of the absorbance ratio, Log εII/Log εI=1.073~1.109. They have inhibited the ATPase-activity to the greatest extent. These findings suggest that a certain angle between the flavone rings B and C plays an important role for the inhibition of the enzyme activity and thus the cytotoxicity.  相似文献   
36.
The flavonoids isolated from the leaves ofRhododendron brachycarpum, were identified as quercetin, avicularin, quercitrin and hyperin.  相似文献   
37.
Summary: Purpose: A prospective series of 643 persons with epilepsy attending a reference neurologic center in Medellin, Colombia, was examined by computed tomography (CT scan) or serology or both with the enzyme-linked immunoelectrotransfer blot assay (EITB) to assess the prevalence of Taenia solium cysticercosis. Methods: All presenting patients were consecutively enrolled in the study. Five hundred forty-six persons underwent cerebral CT scans; 376 of them also had serum EITB performed. Results: Prevalence of neurocys@ercosis by CT scan was 13.92%. Overall prevalence of T. solium antibodies with EITB was 9.82%, but for those with late-onset epilepsy (onset after age 30 years), prevalence increased to 17.5% and 19% for those who originated from outside urban Medellin. Seroprevalence in individuals with mixed lesions (cysts and calcifications) was 88.2% and 64.10% in those with live cysts. Conversely, only 2.72% of persons with CT findings not related to neurocysticercosis had positive EITB tests. Conclusions: Our study shows that an important proportion of individuals with epilepsy have radiologic or serologic evidence of T. solium infection, suggesting that neurocysticercosis is an important etiology for epilepsy in Colombia.  相似文献   
38.
39.
We report, for the first time, the light microscopical and ultrastructural appearance of ZnT3-immunoreactivities in the ependymal cells of the central canal of the mouse spinal cord. Light microscopy revealed the presence of ZnT3-immunoreactive (Ir) ependymal cells in 1 microm thick epon sections stained by the ABC method. The ZnT3-Ir cells were observed at all levels of the spinal cord, but were a little more numerous in lumbosacral segments than in cervicothoracic segments. The ZnT3-Ir cells had large, ovoid nuclei with abundant cytoplasm, and protruded into the lumen of the central canal. Our ultrastructural findings suggest that the ZnT3-Ir ependymal cells possess secretory activity directed towards the central canal. We propose that they may play a role in the trans-ependymal mechanism responsible for zinc homeostasis between cerebrospinal fluid and the central area of the gray matter.  相似文献   
40.
Nitric oxide (NO) inhalation therapy has been employed in the management of acute respiratory distress syndrome (ARDS), in order to improve oxygenation. Several factors have been implicated as being responsible for the action of inhaled NO. Alveolar recruitment methods, such as prone positioning and a sufficient positive end expiratory pressure (PEEP), have been identified as having a positive impact on the NO response. A Recruitment maneuver (RM) was introduced for the treatment of ARDS, along with a lung protective strategy. Here, we hypothesized that a RM may further augment the oxygenation of patients treated with NO inhalation. Therefore, the effects of the inhalation of NO, either in combination with a RM, or separately, were evaluated on patients with ARDS for their enhancing action. 23 patients with ARDS were enrolled, and divided into three groups. The patients in group 1 (n=11) were treated with 5 ppm NO via inhalation, followed by a RM, applying a sustained inflation pressure of 30 - 35 cmH2O for 30 seconds. Group 2 (n=6) received a RM alone, while group 3 (n=3) was treated with NO inhalation alone. The oxygenation and hemodynamic parameters were obtained prior to, and 2, 12, and 24 h after, the respective treatment procedures. For group 1, the PaO2/FiO2 increased from its initial value of 171.8 +/- 67.8 to 203.2 +/- 90.0 2 h after NO inhalation. Further improvement was noted with the continual application of the RM reaching, 215.5 +/- 74.6 (p=0.05) and 254.2 +/- 109.5 (p < 0.05), after 12 and 24 h, respectively. Initially 7 of the subjects did not respond to NO inhalation, but 3 of these non-responders changed into responders 12 h after the RM. The changes in the PaO2/FiO2 from baseline at each time period were greater in group 1 than in the other groups, but with no statistical significance. The hemodynamics of the patients was not significantly altered during the entire study period. We conclude that the combined application of NO inhalation and a RM could be beneficial and safe for patients with ARDS, showing an enhancing effect in improvement of oxygenation.  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